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The trends afoot for miniaturization of high-frequency electronic devices require integration of active and passive high-frequency circuit elements within a single system. This high level of accomplishment not only calls for a cutting-edge integration technology but also necessitates accommodation of the corresponding circuit components within a restricted space in applications such as implantable devices, internet of things (IoT), or 5G communication systems. At the same time, size reduction does not remain the only demand. The performance requirements of the abovementioned systems form a conjugate demand to that of the size reduction, yet with a contrasting nature. A compromise can be achieved through constrained numerical optimization, in which two kinds of constrains may exist: equality and inequality ones. Still, the high cost of electromagnetic-based (EM-based) constraint evaluations remains an obstruction. This issue can be partly mitigated by implicit constraint handling using the penalty function approach. Nevertheless, securing its performance requires expensive guess-work-based identification of the optimum setup of the penalty coefficients. An additional challenge lies in allocating the design within or in the vicinity of a thin feasible region corresponding to equality constraints. Furthermore, multimodal nature of constrained miniaturization problems leads to initial design dependency of the optimization results. Regardless of the constraint type and the corresponding treatment techniques, the computational expenses of the optimization-based size reduction persist as a main challenge. This thesis attempts to address the abovementioned issues specifically pertaining to optimization-driven miniaturization of high frequency structures by developing relevant algorithms in a proper sequence. The first proposed approach with automated adjustment of the penalty functions is based on the concept of sufficient constraint violation improvement, thereby eliminating the costly initial trial-and-error stage for the identification of the optimum setup of the penalty factors. Another introduced approach, i.e., correction-based treatment of the equality constraints alleviates the difficulty of allocating the design within a thin feasible region where designs satisfying the equality constraints reside. The next developed technique allows for global size reduction of high-frequency components. This approach not only eliminates the aforementioned multimodality issues, but also accelerates the overall global optimization process by constructing a dimensionality-reduced surrogate model over a pre-identified feasible region as compared to the complete parameter search space. Further to the latter, an optimization framework employing multi-resolution EM-model management has been proposed to address the high cost issue. The said technique provides nearly 50 percent average acceleration of the optimization-based miniaturization process. The proposed technique pivots upon a newly-defined concept of model-fidelity control based on a combination of algorithmic metrics, namely convergence status and constraint violation level. Numerical validation of the abovementioned algorithms has also been provided using an extensive set of high-frequency benchmark structures. To the best of the author´s knowledge, the presented study is the first investigation of this kind in the literature and can be considered a contribution to the state of the art of automated high-frequency design and miniaturization.

Crowd simulation focuses on modeling the movements and behaviors of large groups of people. This area of study has become increasingly important because of its several applications in various fields such as urban planning, safety, and entertainment. In each of these domains, the presence of virtual agents exhibiting realistic behavior greatly enhances the quality of the simulations. However, the inherently multifaceted and intricate nature of human behavior presents a unique challenge, necessitating the effective combination of multiple behavior models. This thesis introduces a novel theoretical framework for modeling human behavior in crowd simulations, addressing the unresolved issue of combining a plethora of behavior models, often developed in isolation. The proposed framework decomposes human behavior into fundamental driving stimuli, which are then represented graphically through the heatmap paradigm. Subsequently, the agent behavior is influenced by the heatmaps, which guide them toward attractive areas and steer them away from repulsive locations based on the encoded stimuli. A key advantage of this approach lies in the ability to combine heatmaps using well-defined color operations, effectively integrating different aspects of human behavior. Furthermore, the heatmap paradigm facilitates objective comparison of simulation output with real-world data, employing image similarity metrics to evaluate model accuracy. To realize this framework, the thesis presents a modular software architecture designed to support various tasks involved in crowd simulation, emphasizing the separation of concerns for each task. This architecture comprises a collection of abstract modules, which are subsequently implemented using appropriate software components to realize the underlying features, resulting in the Agora framework. To assess the ability of Agora to support the various tasks involved in crowd simulation, two case studies are implemented and analyzed. The first case study simulates tourists visiting Þingvellir national park in Iceland, examining how their behavior is influenced by the visibility of the surrounding environment. The second case study employs Agora to model the thermal and density comfort levels of virtual pedestrians in an urban setting. The results demonstrate that Agora successfully supports the development, combination, and evaluation of crowd simulation models against real-world data. The authoring process, assisted by Agora, is significantly more streamlined compared to its native counterpart. The integration of multiple models is achieved by combining the heatmaps, resulting in plausible behavior, and the model assessment is made convenient through the evaluator within the framework. The thesis concludes by discussing the implications of these findings for the field of crowd simulation, highlighting the contributions and potential future directions of the Agora framework., Mannfjöldahermun fæst við gerð líkana af hreyfingu og hegðun stórra hópa af fólki. Mikilvægi þessa rannsóknasviðs hefur vaxið stöðugt vegna hagnýtingar á margvíslegum vetvangi, eins og til dæmis á vetvangi borgarskipulags, öryggis og afþreyingar. Þegar sýndarmenni hegða sér á sannfærandi hátt, leiðir það til betri hermunar fyrir þessi notkunarsvið. En mannleg hegðun er í eðli sínu margbrotin og flókin og því er það sérstök áskorun við smíði sýndarmenna að sameina, með áhrifaríkum hætti, mörg mismunandi hegðunarlíkön. Þessi ritgerð kynnir nýja fræðilega umgjörð líkanasmíði mannlegrar hegðunar fyrir mannfjöldahermun, sem tekur á þeim óleysta vanda að sameina fjölda hegðunarlíkana, sem oft eru þróuð með aðskildum hætti. Umgjörðin brýtur mannlega hegðun niður í grundvallar drifáreiti, sem eru sett fram grafískt útfrá hugmyndafræði hitakorta. Sýndarmennin hegða sér síðan undir áhrifum frá hitakortunum, sem vísa þeim í áttina að aðlaðandi svæðum og stýra þeim burt frá fráhrindandi svæðum, útfrá hinu umritaða áreiti. Lykilkostur þessarar nálgunar er sá eiginleiki að geta blandað saman hitakortum með vel skilgreindum litaaðgerðum, sem eru þá í raun samþætting mismunandi hliða mannlegrar hegðunar. Hitakortshugmyndafræðin auðveldar ennfremur hlutlægan samanburð hermunarúttaks og raungagna með notkun myndsamanburðarmælinga, til að meta nákvæmni líkana. Varðandi útfærslu, þá kynnir þessi ritgerð einingadrifna hugbúnaðarhögun sem er hönnuð til að styðja við ýmsa ferla mannfjöldahermunar, með áherslu á aðskilnað helstu viðfangsefna hvers ferlis. Þessi högun inniheldur safn huglægra eininga, sem síðan eru útfærðar með viðeigandi hugbúnaðarhlutum, sem raungera undirliggjandi eiginleika. Útkoman er sjálf Agora umbjörðin. Tvö sýnidæmi eru útfærð og greind til að meta getu Agoru til að styðja við ýmis mannfjöldahermunarverkefni. Fyrra dæmið hermir eftir ferðamönnum sem heimsækja Þingvallaþjóðgarð, og skoðar hvernig hegðun þeirra verður fyrir áhrifum sýnileika umhverfisins sem umleikur þá. Seinna dæmið nýtir Agoru til að smíða líkan af hitauppstreymis- og þéttleikaþægindum hjá sýndarvegfarendum í borgarumhverfi. Niðurstöðurnar sýna góðan árangur Agoru við að styðja þróun, samþættingu og mat mannfjöldahermunarlíkana gagnvart raungögnum. Þróunarferlið er verulega þjálla með Agoru en með hefðbundnum aðferðum. Samþætting margra líkana tókst með blöndun hitakorta, möguleg hegðun var framkölluð og mat á líkönunum varð þægilegra með umgjörðinni. Ritgerðinni lýkur með því að fjalla um áhrif þessara niðurstaðna á svið mannfjöldahegðunar, með áherslu á nýstálegt framlag þessarar rannsóknar og mögulega framtíðarþróun Agora umgjarðarinnar.

For machine translation (MT) systems to produce accurate and fluent translations, reliable parallel corpora are key. Errors, due to misalignments or inadequate filtering during compilation of a parallel corpus, can have detrimental effects on the performance of an MT system trained on the data. Moreover, when the corpus is too small, the MT system may not be able to capture the complexities of the source and target languages and produce accurate translations. However, obtaining high-quality parallel data is often a challenging task, even more so for languages with a low number of speakers or rich morphology exacerbating the data sparsity problem. It is thus imperative to develop accurate methods for processing parallel corpora that can help make the most of what is available. In this thesis, we address this challenge by exploring various methods for processing parallel corpora to maximize their usefulness for MT. First, we investigate a variety of classifiers and scoring mechanisms used for filtering parallel corpora, looking into how efficient they are at removing data detrimental to MT training and retaining useful data. We find that different filtering strategies suit different datasets and that filtering separately for different translation directions can yield better translations in downstream MT tasks. Second, we examine different approaches to sentence alignment, compare their effectiveness, and show that combining multiple methods can improve alignment accuracy. Third, we experiment with comparable corpora mining methods to extract even more useful data from sentences that had previously been discarded, showing that this often overlooked data is a potential source of useful training data. Finally, we manually evaluate translations generated by MT systems trained on our processed datasets, most suitable for each translation direction, confirming the advantages of our applied methods. Our findings highlight the importance of careful processing and curation of parallel corpora for MT. We propose approaches for maximizing the utility of available parallel data, particularly for scenarios where resources are scarce, contributing to the development of more accurate and reliable MT systems., Áreiðanlegar samhliða málheildir eru lykillinn að því að hægt sé að þjálfa þýðingarvélar, sem geta myndað nákvæmar þýðingar sem flæða vel á markmálinu. Skekkjur í þjálfunargögnum, sem koma til vegna rangrar samröðunar setninga eða ófullnægjandi síunar við smíði samhliða málheilda, geta spillt gæðum þýðingarvélar sem þjálfuð er á gögnunum. Of lítil samhliða málheild getur jafnframt orðið til þess að þýðingarvélin nái ekki tökum á málfræði eða öðrum blæbrigðum frum- og markmálanna og myndi þess vegna ónákvæmar þýðingar.Það getur hins vegar verið flókið og erfitt að tryggja hámarksgæði þjálfunargagna við úrvinnslu samhliða texta, ekki síst þegar um er að ræða texta á tungumálum sem fáir tala eða þegar flóknar beygingar og virk orðmyndun auka á vandann við að greina rýr gögn. Þegar samhliða málheildir eru settar saman er því afar mikilvægt að þróa nákvæmar aðferðir sem miða að því að nýta sem allra best þau gögn sem til eru Í þessari ritgerð tökumst við á við þetta vandamál með því að kanna ýmsar aðferðir til að vinna gögn við smíði samhliða málheilda með það að leiðarljósi að hámarka notagildi gagnanna fyrir vélþýðingar. Í fyrsta lagi rannsökum við nokkrar gerðir flokkara og matsaðferðir sem notaðar eru til að sía samhliða málheildir. Við skoðum hversu árangursríkar þær eru til að fjarlægja setningapör sem geta dregið úr gæðum þýðingarvéla ef þau eru hluti þjálfunargagna og hversu líklegar aðferðirnar eru til að halda eftir þeim setningapörum sem búast má við að séu best fallnar til að bæta þýðingarvélarnar. Við komumst að því að mismunandi síunaraðferðir henta mismunandi gagnasöfnun og að með því að sía sérstaklega fyrir hverja þýðingarátt má bæta gæði þýðinga þeirra véla sem þjálfaðar eru á gögnunum. Í öðru lagi skoðum við mismunandi aðferðir við samröðun setninga, berum saman markvirkni þeirra og sýnum að með því að láta margar mismunandi aðferðir vinna saman getum við aukið nákvæmni samröðunarinnar. Í þriðja lagi gerum við tilraunir með aðferðir til að vinna samhliða gögn úr sambærilegum málheildum, og beitum þeim aðferðum til að draga nýtileg gögn úr setningum og setningapörum sem hafnað hefur verið á fyrri stigum í smíði þjálfunargagnanna. Við sýnum með nokkrum tilraunum að mögulegt er að nýta þessi gögn, sem yfirleitt er litið fram hjá, til að stækka samhliða þjálfunarmálheildir með nýtilegum gögnum og þar með bæta þýðingarvélar sem þjálfaðar eru á þeim. Að lokum metum við handvirkt þýðingar myndaðar af þýðingarvélum sem þjálfaðar eru á gögnum sem unnin hafa verið með okkar aðferðum, en það mat staðfestir gagnsemi þeirra aðferða sem við beitum. Niðurstöður okkar undirstrika mikilvægi vandaðrar greiningar og gagnavinnslu við smíði samhliða málheilda sem notaðar eru til að þjálfa þýðingarvélar. Við kynnum aðferðir sem hámarka notagildi tiltækra samhliða gagna, ekki sístþegar takmarkað magn gagna er fyrir hendi, og stuðlum þannig að þróun nákvæmari og áreiðanlegri þýðingarvéla.

Magnetoresistance oscillations, also known as Shubnikov-de Haas (SdH) oscil- lations, is a well-known phenomena that results from the quantization of electron orbits in the presence of a magnetic field. These oscillations have been extensively studied and are a valuable experimental tool for extracting electronic charge densi- ties and spin-orbit interaction (SOI) couplings, such as Rashba and Dresselhaus cou- plings. Although 2DEGs with large Rashba, Dresselhaus, and g-factors are available, the current theoretical picture of explaining SdH behavior is not able to account for all those factors. Our findings show that by using a Poisson summation formula, we can analyze magneto-oscillations in 2DEGS systems with Rashba, Dresselhaus, and Zeeman couplings. The Poisson summation formula naturally separates the magne- tooscillations into fast and slow components which facilitates the analysis of the spin- orbit contribution. In this Ph.D. thesis, we investigate magnetooscillations in com- plex 2DEGs using both analytical and numerical methods thus providing a unique and comprehensive approach. Using the analytical approach, we identified a new condition for the vanishing of spin-orbit-related beatings. With numerical method, we are abled to extract both SOI couplings from the SdH oscillations independently of their Zeeman strength and electrical charge density. Additionally, we found that the behavior of SdH oscillations in such systems can be greatly influenced by the an- gle at which the in-plane magnetic field is tilted. This research contributes to the ongoing process of the development of novel spintronic devices., Reykjavik University, Ph.D fund

Nanostructures made from crystalline silicon, especially in the form of nanowires (SiNWs), have shown great potential as pressure sensors due to their unique properties such as high sensitivity, small size, and low power consumption. When a force is applied to SiNWs, they undergo a mechanical deformation that results in a change in their electrical resistance. Such an effect has been referred to as the piezoresistance effect. This change in resistance can be measured and used to determine the amount of pressure being applied. By integrating these nanowires into a sensor device, it is possible to create a highly sensitive pressure sensor that can be used in a variety of applications such as in medical devices, aerospace technology, and robotics. Many available techniques can be applied to fabricate such SiNWs. One of the simplest ones is the so-called metal-assisted-chemical-etching (MACE) which has gained significant attention in recent years. This process involves the use of a metal catalyst, such as silver, to etch silicon in a controlled manner to produce nanowires with high aspect ratios. The nanowires can be integrated with other materials to create a flexible and stretchable sensor that can conform to curved surfaces and be used in a variety of applications. One advantage of using MACE to fabricate silicon nanowires is that it is a low-cost and scalable process. This makes it possible to produce large quantities of nanowires at a low cost, which is important for commercial applications. This thesis describes the fabrication of SiNWs using MACE and applications of the SiNWs as an accurate and sensitive pressure sensor for an isostatic and uniaxial load. Its use was further extended to fabricate a novel, small, and compact, breath sensor that could potentially have an impact on sleep research.

Machine Learning (ML) is extensively used in diverse healthcare applications to aid physicians in diagnosing and identifying associations, sometimes hidden, between dif- ferent biomedical parameters. This PhD thesis investigates the interplay of medical images and biosignals to study the mechanisms of aging, knee cartilage degeneration, and Motion Sickness (MS). The first study shows the predictive power of soft tissue radiodensitometric parameters from mid-thigh CT scans. We used data from the AGES-Reykjavik study, correlating soft tissue numerical profiles from 3,000 subjects with cardiac pathophysiologies, hy- pertension, and diabetes. The results show the role of fat, muscle, and connective tissue in the evaluation of healthy aging. Moreover, we classify patients experiencing gait symptoms, neurological deficits, and a history of stroke in a Korean population, reveal- ing the significant impact of cognitive dual-gait analysis when coupled with single-gait. The second study establishes new paradigms for knee cartilage assessment, correlating 2D and 3D medical image features obtained from CT and MRI scans. In the frame of the EU-project RESTORE we were able to classify degenerative, traumatic, and healthy cartilages based on their bone and cartilage features, as well as we determine the basis for the development of a patient-specific cartilage profile. Finally, in the MS study, based on a virtual reality simulation synchronized with a moving platform and EEG, heart rate, and EMG, we extracted over 3,000 features and analyzed their importance in predicting MS symptoms, concussion in female ath- letes, and lifestyle influence. The MS features are extracted from the brain, muscle, heart, and from the movement of the center of pressure during the experiment and demonstrate their potential value to advance quantitative evaluation of postural con- trol response. This work demonstrates, through various studies, the importance of ML technologies in improving clinical evaluation and diagnosis contributing to advance our understanding of the mechanisms associated with pathological conditions., Tölvulærdómur (Machine Learning eða ML) er algjörlega viðurkennt og nýtt í ýmsum heilbrigðisþjónustuviðskiptum til að hjálpa læknunum við að greina og finna tengsl milli mismunandi líffærafræðilegra gilda, stundum dulinna. Þessi doktorsritgerð fjallar um samspil læknisfræðilegra mynda og lífsmerkja til að skoða eðli aldrunar, niðurbrot hnéhringjar og hreyfikerfissjúkdóms (Motion Sickness eða MS). Fyrsta rannsóknin sýnir spárkraft midjubeins-CT-skanna í því að fullyrða staðfest- ar meðalþyngdarlíkön, þar sem gögn úr AGES-Reykjavik-rannsókninni eru tengd við hjarta- og æðafræðilega sjúkdóma, blóðþrýstingsveikindi og sykursýki hjá 3.000 þátt- takendum. Niðurstöðurnar sýna hlutverk fitu, vöðva og tengikjarna í mati á heilbrigð- um öldrun. Þar að auki flokkum við sjúklinga sem upplifa gangvandamál, taugaein- kenni og sögu af heilablóðfalli í kóreanskri þjóð, þar sem einstök gangtaksskoðun er tengd saman við tvískoðun. Önnur rannsóknin setur upp ný tölfræðisfræðileg umhverfisviðmið til matar á hnéhringju með samhengi 2D og 3D mynda sem aflað er úr CT og MRI-skömmtum. Í rauninni höfum við getuð flokkað niðurbrots-, slys- og heilbrigðar hnéhringjur á grundvelli bein- og brjóskmerkja með raun að sækja niðurstöður í umfjöllun um sjúklingar eftir réttu einkasniði. Að lokum, í MS-rannsókninni, notum við myndræn tilraun samþættaða með hreyfan- legan grundvöll og EEG, hjartslátt, EMG þar sem yfir 3.000 aðgerðir eru útfránn og greindir til að átta sig á áhrifum MS, höfuðárás hjá konum sem eru íþróttamenn, lífs- stíl og fleira. Einkenni MS eru aflöguð úr heilanum, vöðvum, hjarta og frá hreyfingum þyngdupunktsins á meðan tilraunin stendur og sýna mög.

In this thesis, two methods for automatic enumeration of permutation classes are studied. The first method extends on the theory of combinatorial exploration. We review how combinatorial exploration works as a two phases process: the first phase creating a universe of rules and the second one searching that universe for a solution to a given enumeration problem. After that, we identify a situation where the search step does not succeed to provide an answer despite the universe "containing" (in some sense) one. We present a way to overcome this shortcoming by developing a new theory that allows to find these "answers". Then, we demonstrate how combinatorial exploration can be extended to apply to problems where some additional statistics are involved. This theory is applied to enumerate permutation classes for which we introduce a new decomposition strategy called fusion. Combining all the tools discussed so far, we provide the first direct enumeration of Av(1342). For the second method, we study the staircase encoding of permutations, which maps a permutation to a staircase grid with cells filled with permutations. We study the restriction of the staircase encoding to many permutation classes where the encoding becomes a bijection. For each of these classes, we describe the image of the bijections using independent sets of graphs weighted with permutations. We then enumerate the permutation classes by deriving the generating function for the independent sets and then for their weighted counterparts. We use our results to uncover some unbalanced Wilf-equivalences of permutation classes., Í þessari ritgerð er fjallað um tvær sjálfvirkar aðferðir við að telja umraðanaflokka. Fyrri aðferðin útvíkkar fræðin um fléttufræðilega könnun. Við rifjum upp hvernig fléttufræðileg könnun virkar í tveimur skrefum: fyrsta skrefið býr til heim af reglum, og seinna skrefið leitar í þeim heimi að lausn að talningarvandamáli. Að því loknu finnum við aðstæður þar sem leitin skilar engri niðurstöðu, jafnvel þó heimurinn "innihaldi" (í ákveðnum skilningi) lausn. Við sýnum hvernig megi yfirstíga þetta vandamál með því að þróa nýja fræði sem leifir okkur að finna þessar "lausnir". Síðan sýnum við hvernig nota megi fléttufræðilega könnun megi útvíkka til að takast á við vandamál þar sem margar tölfræðir koma við sögu. Þessari fræði er beitt á umraðanaflokka, og þar skilgreinum við nýja kænsku sem kallast samruni. Með því að nota allar þessar niðurstöður tekst okkur að gefa fyrstu beinu talninguna á Av(1342). Seinni aðferðin byggir á stigakóðun umraðana, sem varpar umröðunum í stigalaga kóðun þar sem hvert hólf inniheldur umröðun. Við rannsökum einskorðun þessarar stigakóðunar á umraðanaflokka þar sem kóðunin er gagntæk vörpun. Fyrir þessa flokka lýsum við mynd vörpunarinnar með því að nota óháð mengi í netum vigtuð með umröðunum. Við teljum umraðanaflokkana með því að finna framleiðniföll þessara óháðu mengja, með og án vigtun. Við notum þessar niðurstöður til þess að finna ójöfn Wilf-jafngildi umraðanaflokka.

Numerical simulations done at the Nanophysics Center at Reykjavík University indicate that under constant illumination from a sufficiently energetic monochromatic light source, a space-charge limited photoemission can cause current modulation in a vacuum microdiode. The period of this modulation can be tuned by the potential applied to the diode, and is comparable to the transit time of electrons across the diode gap that can be as small as hundreds of femtoseconds. This thesis presents work on gallium-arsenide-germanium photocathodes that were fabricated and tested as a possible component for such a tunable microdiode oscillator. A second topic of this thesis is the investigation of photoemission in microdiodes from laser pulses that are shorter than the characteristic transit time of the diode. This was done using a molecular dynamics code developed at RU. The transition from source-limited emission to space-charge limited emission is studied and compared to commonly used models. It is also shown how to obtain optimal brightness for such an electron pulse, an important issue for time resolved electron microscopy, free-electron lasers and other applications. Lastly, random pattern silicon nanowires were fabricated and studied with regard to piezoresistance, with pressure-sensing applications in mind. They were found to exhibit resistance-dependant behavior both under isostatic and uniaxial pressure., Icelandic Centre for Research project grant no. 174512-051 Energy research fund of Landsvirkjun no. NÝR-01-2021 Reykjavík University Doctoral fund

Monitoring brain cortical activity is essential to decipher and understand neurophysiological behaviour. A wide amount of tools and experimental setups has been developed to stimulate, record and analyze brain activity. The identification of quantitative metrics to assess this activity during specific tasks remains an essential requirement, as it could lead to improve diagnostics, describe objectively self-assessed condition, or track variation during long-term studies. This thesis introduces the development of tools and paradigms to assess brain cortical activity during cognitive tasks. It introduces a complete set of analyses based on EEG signals, under two main scopes, schizophrenia and postural control. The first part of the work evaluates the impact of a potential therapeutic solution for patients with schizophrenia. A longitudinal study case is introduced, where psychometrics data are compared with three types of analysis from EEG data: temporal, spectral and connectivity. The small sample size prevents us to draw definitive conclusion, however, this work reveals the interest to use EEG-based metrics to complete the standard psychometrics assessment. The second part of the work focuses on postural control, using a novel measurement setup, called BioVRSea, combining virtual reality and a moving platform. The brain cortical activity of more than 150 healthy individuals have been investigated during this experiment. A robust neurophysiological reference has been identified using power spectral density. Moreover, combining brain connectivity and microstate segmentation, network dynamics reveal a coherent brain remodeling throughout the acquisition, strengthening our current knowledge regarding complex postural control. The current work highlights the concrete benefit of using EEG signal to decipher brain cortical activity. The tools developed in this thesis are of interest to build a neurophysiological signature of specific cognitive tasks, that will be crucial for a further understanding of neurodegenerative disease., Að fylgjast með starfsemi heilaberki er nauðsynlegt til að útskýra og skilja tauga-lífeðlisfræðilega hegðun. Fjölbreytt útval af tólum og tilraunauppsetningum hefur verið þróað til að örva, vista og greina heilastarfsemi. Það er nauðsynleg krafa að finna magnmælingu til að greina þessa starfsemi í ákveðnu verkefni, því það gæti leitt að beturumbættu greiningarferli, útskýrt hlutlægu sjálfsmats ástandi, eða fylgst með breytingum í lang-tíma rannsóknum. Þessi ritgerð kynnir þróunn tóla og hugmyndafræði til að meta heilaberka starfsemi við vitræn verkefni. Ritgerðinn kynnir heilt safn af greiningum byggt á EEG merkj- um, í tvem megin sviðum, geðklofa og líkamsstöðustjórnun. Fyrsti hluti verkefnisins metur áhrifin af mögulegum meðferðarlegum lausnum fyrir sjúklinga með geðklofa. Kynnt er langtímarannsóknartilvik, þar sem þar sem sálfræðigögn eru borin saman við þrenns konar greiningar úr heilarita gögnum: tímabundnum, litrófs- og tengingum. Lítil úrtaksstærð kemur í veg fyrir að við getum dregið endanlegar ályktanir, en þessi vinna sýnir áhugann á því að nota heilalínuritaða mælikvarða til að ljúka stöðluðu sálfræðimati. Annar hluti verksins fjallar um líkamsstöðustýringu, með því að nota nýja mæling- aruppsetningu, sem kallast BioVRSea, sem sameinar sýndarveruleika og hreyfanlegan vettvang. Heilabarkarvirkni af meira en 150 heilbrigðra einstaklinga hefur verið rann- sökuð í þessari tilraun. Öflug taugalífeðlisfræðileg tilvísun hefur fundist með því að nota kraftrófsþéttleika. Þar að auki, með því að sameina heilatengingu og örstöðu- skiptingu, sýnir netverkun samfellda endurgerð heilans í gegnum tökuna, sem styrkir núverandi þekkingu okkar varðandi flókna líkamsstöðustjórnun. Þessi rannsókn undirstrikar raunverulegan ávinning af því að nota EEG merki til að ráða virkni heilabarka. Tólin sem þróuð eru í þessari ritgerð eru mikilvæg til að byggja upp taugalífeðlisfræðilega undirskrift ákveðinna vitræna verkefna, sem mikilvæg eru fyrir frekari skilning á taugahrörnunarsjúkdómum.

The dissertation is a collection of the three leading publications, which result from the doctoral research project ‘Sustainable Energy Supply in Remote Arctic Areas - Analysis of resources, technology and policies for developing energy systems’. The research focuses on which energy resources are available in the Arctic and how the various resources can be harvested with different mature energy technology options for remote Arctic communities. Mature energy generation technology means that the operation under harsh and cold climatical conditions is well proven. Furthermore, the current energy situation among remote Arctic communities will be mapped out, with an analysis of which energy sources are used, the share of the different sources, and the energy demand of remote communities. After explaining the different energy generation options and main drivers for using renewable energy in remote Arctic communities, three case studies have been conducted. The case studies examine the viability of a potential energy transition for Arctic communities. The case studies also share some insights from field visits in remote communities on generating electricity with renewables and potential energy saving potentials. The last part elaborates on different integration strategies for renewable energy options. The focus lies on how to finance the energy transition in remote Arctic communities, which can help to structure the energy transition process financially. The dissertation finishes with an overall conclusion on the importance of renewable energy for Arctic communities. The research shows that renewable energy can be vital for remote communities to become more energy independent and lower the energy cost burden., Iceland Research Fund, Grant Nr. 195846-053; e Landsvirkjun Energy Fund, Grants NÝR-10 – 2019, NÝR-17 – 2020, NÝR-15 - 2021

Concurrency as a phenomenon is observed in most of the current computer science trends. However the inherent complexity of analyzing the behavior of such a system is incremented due to the many different models of concurrency, the variety of applications and architectures, as well as the wide spectrum of specification languages and demanded correctness criteria. For the scope of this thesis we focus on state based models of concurrent computation, and on modal logics as specification languages. First we study syntactically the process algebras that describe several different concurrent behaviors, by analyzing their equational theories. Here, we use well-established techniques from the equational logic of processes to older and newer setups, and then transition to the use of more general and novel methods for the syntactical analysis of models of concurrent programs and specification languages. Our main contributions are several positive and negative axiomatizability results over various process algebraic languages and equivalences, along with some complexity results over the satisfiability of multi-agent modal logic with recursion, as a specification language., Samhliða sem fyrirbæri sést í flestum núverandi tölvunarfræði stefnur. Hins vegar er eðlislægt flókið að greina hegðun slíks kerfis- tem er aukið vegna margra mismunandi gerða samhliða, fjölbreytileikans af forritum og arkitektúr, svo og breitt svið forskrifta mælikvarða og kröfðust réttmætisviðmiða. Fyrir umfang þessarar ritgerðar leggjum við áherslu á ástandsbundin líkön af samhliða útreikningum og á formlegum rökfræði sem forskrift tungumálum. Fyrst skoðum við setningafræðilega ferlialgebrurnar sem lýsa nokkrum mismunandi samhliða hegðun, með því að greina jöfnukenningar þeirra. Hér notum við rótgróin tækni mynda jöfnunarrökfræði ferla til eldri og nýrri uppsetningar, og síðan umskipti yfir í notkun almennari og nýrra aðferða fyrir setningafræðileg greining á líkönum samhliða forrita og forskriftartungumála. Helstu framlög okkar eru nokkrar jákvæðar og neikvæðar niðurstöður um axiomatizability yfir ýmis ferli algebrumál og jafngildi, ásamt nokkrum samSveigjanleiki leiðir af því að fullnægjanleiki fjölþátta formrökfræði með endurkomu, sem a forskrift tungumál., RANNIS: `Open Problems in the Equational Logic of Processes’ (OPEL) (grant No 196050-051) Reykjavik University research fund: `Runtime and Equational Verification of Concurrent Programs' (ReVoCoP) (grant No 222021)

Majorana zero modes have recently been proposed as a solution to obtain fault-tolerant quantum computation. They are quasiparticle excitations in quantum systems at the nanoscale with the potential to function as qubits, the basic building blocks of quantum computers. Their topological properties hold promise to counter the decoherence problem, where quantum coherence is lost due to coupling with the environment, which is one of the main challenges for upscaling the number of qubits in a quantum computer. In this work, Majorana zero modes in core-shell nanowire systems are investigated. Core-shell nanowires are tubular conductors that commonly have polygonal cross-section geometry due to crystallographic qualities. Semiconductors with proximity-induced superconductivity, large g-factors and Rashba spin-orbit coupling, can be tuned by an external magnetic field to host Majorana zero modes. Corner-localization of the lowest energy states in polygonal core-shell nanowires allows for hosting multiple Majorana zero modes within a single nanowire system. Three-dimensional nanowires are modeled using the Bogoliubov-de Gennes Hamiltonian, which is solved numerically by diagonalization. Effects of variable core and shell geometry are analyzed and triangular wires with hexagonal cores are found to have particularly large energy separations between the first and second groups of energy states, which is favorable for experimental hosting of Majorana zero modes. Braiding in such a system is discussed and for the realization of real space braiding, a dual core wire is suggested to include the necessary degrees of freedom for the simplest non-commutative braiding operation. The relation between Andreev reflection and propagation of the superconductivity property is studied by modeling partially proximitized wire shells, with radial, angular and longitudinal interfaces, corresponding to common experimental platforms. Varying compatibility is found with Andreev reflection. Flux-periodic oscillations in the energy spectra of proximitized shells are explored along with the effects of geometry, Zeeman and spin-orbit interaction. Instances are shown where the periodicity of the lowest energy state is found to separately display normal, superconducting and fractional flux quanta. To gain insight into the structure of topological invariants, the first Chern number in particular, Stokes' theorem for bivector-valued fields is analyzed and visualized using geometric calculus. The findings show how the multiple components necessary for the emergence of Majorana zero modes each have complex subtleties and interdependencies, and in what way they should be investigated to come closer to the technological realization of Majorana zero modes., The Icelandic Research Fund, grant no. 206568-051 and Reykjavik University Research Fund, project no. 218043

Publisher's version (útgefin grein), Multiple-input multiple-output (MIMO) antennas are considered to be the key components of fifth generation (5G) mobile communications. One of the challenges pertinent to the design of highly integrated MIMO structures is to minimize the mutual coupling among the antenna elements. The latter arises from two sources, the coupling in the free space and the coupling currents propagating on a ground plane. In this paper, an array of H-shaped parasitic patches is proposed as a decoupling structure for compact MIMO antennas to reduce propagation of the coupling currents on a shared ground plane. The proposed decoupling structure is generic, and it can be applied to different antenna configurations as demonstrated in the work. Furthermore, it is employed to develop a new high-performance compact dual-band MIMO structure featuring acceptable level of element coupling at both operating frequencies. The design is validated both numerically and experimentally. The mutual coupling levels are less than -17 dB and -20 dB, with the total efficiency of 89% and 90%, and the realized gain of 6.6 dB and 7 dB at the two resonant frequencies of 5 GHz and 6 GHz, respectively. Topological complexity of the compact MIMO systems featuring elaborated decoupling structures, a large number of geometry parameters, as well as the necessity of handling multiple performance figures, constitute the major challenges of antenna design, in particular, its re-design for various specifications. To alleviate these difficulties, the paper also provides a procedure for rapid geometry scaling of the dual-band MIMO antennas. Our approach is based on inverse surrogate modeling methods, and results in numerically-derived expressions that enable a precise control over the operating antenna bands within broad ranges thereof (from 4 GHz to 8 GHz for the lower band, and from 1.1 to 1.3 ratio of the upper to lower operating frequency). The aforementioned procedure is accompanied by an optimization-based design refinement scheme. A practical utility of the procedure is corroborated using multiple verification case studies as well as physical measurements of the antenna designed for the exemplary set of performance specifications.

Publisher's version (útgefin grein), Multiple-input multiple-output (MIMO) antennas are considered to be the key components of fifth generation (5G) mobile communications. One of the challenges pertinent to the design of highly integrated MIMO structures is to minimize the mutual coupling among the antenna elements. The latter arises from two sources, the coupling in the free space and the coupling currents propagating on a ground plane. In this paper, an array of H-shaped parasitic patches is proposed as a decoupling structure for compact MIMO antennas to reduce propagation of the coupling currents on a shared ground plane. The proposed decoupling structure is generic, and it can be applied to different antenna configurations as demonstrated in the work. Furthermore, it is employed to develop a new high-performance compact dual-band MIMO structure featuring acceptable level of element coupling at both operating frequencies. The design is validated both numerically and experimentally. The mutual coupling levels are less than -17 dB and -20 dB, with the total efficiency of 89% and 90%, and the realized gain of 6.6 dB and 7 dB at the two resonant frequencies of 5 GHz and 6 GHz, respectively. Topological complexity of the compact MIMO systems featuring elaborated decoupling structures, a large number of geometry parameters, as well as the necessity of handling multiple performance figures, constitute the major challenges of antenna design, in particular, its re-design for various specifications. To alleviate these difficulties, the paper also provides a procedure for rapid geometry scaling of the dual-band MIMO antennas. Our approach is based on inverse surrogate modeling methods, and results in numerically-derived expressions that enable a precise control over the operating antenna bands within broad ranges thereof (from 4 GHz to 8 GHz for the lower band, and from 1.1 to 1.3 ratio of the upper to lower operating frequency). The aforementioned procedure is accompanied by an optimization-based design refinement scheme. A practical utility of the procedure is corroborated using multiple verification case studies as well as physical measurements of the antenna designed for the exemplary set of performance specifications., This work was supported in part by the Icelandic Centre for Research (RANNIS) under Grant 206606051, and in part by the National Science Centre of Poland under Grant 2020/37/B/ST7/01448.

Microsatellites are polymorphic tracts of short tandem repeats (STRs) with one to six base-pair (bp) motifs and account for around 3% of the human genome. Just like copying by hand a text where the same word occurs many times in a row, the replication of microsatellites is error prone and frequently adds or removes one or more copies of the repeat motif. As a result, microsatellites mutate several orders of magnitude faster than unique genomic sequences and for a given microsatellite, a population can have many possible length variations. The first objective of this study was to implement a method to jointly determine the number of repeats present at each microsatellite in the genome for a large number of samples. The second goal was to make the determination of repeat numbers more computationally efficient while simultaneously increasing the detection sensitivity of heavily expanded microsatellite alleles, known as repeat expansions. Last, the software was run on two large sets of whole genome sequenced individuals, one from Iceland and the other from the UK biobank. Using the genealogy information available on the Icelandic set, de novo mutation events were detected and the effects of parental sex, age and genotypes on the types and number of mutations found in their offspring were estimated., Um það bil þrjú prósent af erfðamengi mannsins eru örtungl, en þau eru fjölbreytilegar raðir af stuttum samliggjandi endurtekningum þar sem endurtekna röðin er á bilinu einn til sex basar á lengd. Líkt og við afritun á texta þar sem sama orðið er endurtekið oft í röð, þá er villuhættan meiri við afritun örtunglaraða en við aðrar raðir erfðamengisins og afleiðingin er að endurtekningu er bætt við eða hún tapast miðað við upprunalega basaröð. Vegna þessa stökkbreytast örtungl nokkrum stærðargráðum hraðar en aðrar raðir erfðamengisins og fyrir ákveðið örtungl getur hópur af fólki haft margar mismunandi lengdarútgáfur. Fyrsta markmið verkefnisins var að hanna og skrifa hugbúnað sem gæti ákvarðað fjölda endurtekninga fyrir öll örtungl í erfðamenginu hjá mörgun einstaklingum í einu. Næst, var reikniritinu hraðað en það jafnframt gert næmara fyrir stórum útþenslu örtungla samsætum, sem geta valdið mörgum mismunandi heilkennum hjá þeim sem þær bera. Að lokum var hugbúnaðurinn notaður til að meta arfgerð allra einstaklinga í tveimur stórum þýðum, frá Íslandi annars vegar og Bretlandi hins vegar. Ættfræðiupplýsingar um íslenska þýðið voru notaðar til að greina stökkbreytingar í afkvæmum sem ekki fundust í foreldrum og stökkbreytingarnar notaðar til að meta hvernig aldur kyn og arfgerð foreldra hefur áhrif á tegund og fjölda stökkbreytinga sem þeir arfleiða afkvæmi sín að.

The recent advances in the development of coding metasurfaces created new opportunities to elevate the stealthiness of combat aircrafts. Metasurfaces, composed of optimized geometries of meta-atoms arranged as periodic lattices, are devised to obtain desired electromagnetic (EM) scattering characteristics, and have been extensively exploited in stealth applications to reduce radar cross section (RCS). They rely on the manipulation of backward scattering of electromagnetic (EM) waves into various oblique angles. Despite potential benefits, a practical obstacle hindering widespread metasurface utilization is the lack of systematic design procedures. Conventional approaches are largely intuition-inspired and demand heavy designer’s interaction while exploring the parameter space and pursuing optimum unit cell geometries. Another practical obstacle that hampers efficient design of metasurfaces is implicit handling of RCS performance. To achieve essential RCS reduction, the design task is normally formulated in terms of phase reflection characteristics of the unit cells, whereas their reflection amplitudes—although contributing to the overall performance of the structure—is largely ignored. A further practical issue is insufficiency of the existing performance metrics, specifically, monostatic and bistatic evaluation of the reflectivity, especially at the design stage of metasurfaces. Both provide a limited insight into the RCS reduction properties, with the latter being dependent on the selection of the planes over which the evaluation takes place. As a consequence of raised concerns, the existing design methodologies are still insufficient, especially in the context of controlling the EM wavefront through parameter tuning of unit cells. Furthermore, they are unable to determine truly optimum solutions. Therefore, we have introduced a novel machine-learning-based framework for automated and computationally efficient design of metasurfaces realizing broadband RCS reduction. We have employed a three-stage design procedure involving global surrogate-assisted optimization of the unit cells, followed by their local refinement. In its final stage, a direct EM-driven maximization of the RCS reduction bandwidth has been performed, facilitated by appropriate formulation of the objective function involving regularization terms. Moreover, to handle the combinatorial explosion in the design closure of multi-bit coding metasurfaces, a sequential-search strategy has been developed that enabled global search capability at the concurrent unit cell optimization stage. Latterly, the metasurface design task with explicit handling of RCS reduction at the level of unit cells has been introduced that has accounted for both the phase and reflection amplitudes of the unit cells. The design objective has been defined so as to directly optimize the RCS reduction bandwidth at the specified level (e.g., 10 dB) w.r.t. the metallic surface. The appealing feature of the said framework has consisted in its ability to optimize the RCS reduction bandwidth directly at the level of the entire metasurface as opposed to merely optimizing unit cell geometries. Besides, the obtained design has required minimum amount of tuning at the level of the entire metasurface. Lastly, a new performance metric for evaluating scattering characteristics of a metasurface, referred to as Normalized Partial Scattering Cross Section (NPSCS), has been proposed. The metric involved integration of the scattered energy over a specific solid angle, which allows for a comprehensive assessment of the structure performance in a format largely independent of the particular arrangement of the scattering lobes. Our design methodologies have been utilized to design several instances of novel scattering metasurface structures with the focus on RCS reduction bandwidth enhancement and the level of RCS reduction. Experimental validations confirming the numerical findings have been also provided. To the best of the author’s knowledge, the presented study is the first systematic investigation of this kind in the literature and can be considered a step towards the development of efficient, low-cost, and more high performing scattering structures.

Global climate change is one of the most significant challenges that need urgent action in this century. Energy production and consumption, particularly for heat and electricity generation, account for the highest GHG emissions from anthropogenic activities. The world energy demand is projected to increase as the population grows and efforts double to bridge the demand-supply gap in countries yet to achieve universal access to modern energy services. Currently, out of the 770 million people who lack access to electricity worldwide, 580 million live in Africa, predominantly in the Sub-Saharan Africa region. Using advanced energy planning tools to guide national energy objectives and decisions will be critical in addressing energy poverty while shifting to low-carbon fuels in Sub-Saharan Africa. Advanced energy planning tools have a detailed technological representation, account for greenhouse gas (GHG) emissions and cost, and assess low-carbon policies optimally. This work aims to develop a quantitative energy system planning model for Kenya to evaluate pathways towards access to secure, affordable, and sustainable energy services for the 2020 to 2050 period. This thesis is composed of three journal articles that describe the outcome of this work. The first article reviews the existing integrated energy modeling studies done for the Sub-Saharan Africa region at a country or regional level. The reviewed studies show that the models, based on different mathematical approaches and assumptions, inadequately addressed some fundamental energy themes, such as low-carbon policies and energy cost. It is recommended that the SSA countries develop national-scale energy planning models using advanced planning tools, which could be expanded into a regional model. The second article develops a national-scale energy model for Kenya using the advanced bottom-up energy optimization Integrated MARAKAL-EFOM (TIMES) framework. Using the developed Kenya-TIMES model, the study assesses the environmental and techno-economic assessment of power system expansion for three projected demand levels for Kenya for the 2020 to 2045 period. The results indicate that the government will not meet its nationally determined contribution (NDC) GHG reduction targets in the vision demand scenario without implementing low-carbon policies. The third article develops the Kenya-TIMES model further to assess the low-carbon development strategies for Sub-Saharan Africa, using the case of Kenya. This study evaluates the implication of the carbon tax, renewable energy subsidy, renewable portfolio standards, and a hybrid of renewable subsidy and carbon tax policy instruments on Kenya’s power generation expansion for 2020 to 2050 under vision demand level. The GHG emissions are evaluated against Kenya’s NDC emission reduction targets. The results indicate the evaluated low-carbon policy instruments could help achieve emission cuts below the government’s NDC targets. Overall, this work sets a benchmark for developing a national-scale energy planning model using advanced energy planning tools and using it to guide the national energy objectives and decisions that Sub-Saharan Africa countries could adopt., Kenya Electricity Generating Company (KenGen) GRO-Geothermal Training Programme Reykjavik University, Thesis

Publisher's version (útgefin grein), We present preliminary results from the ongoing study entitled "Icelandic AVH-TMS" which aim is to study the effectiveness of repetitive transcranial magnetic stimulation (rTMS) treatment for patients with schizophrenia and with persistent auditory verbal hallucinations (AVH) using symptoms and psychometric scales and high-density EEG system (256 channels). The aim of the present work was to describe cortical topography of the auditory evoked responses like P50 and N100-P300 complex in healthy participants and patients with schizophrenia and to define a robust methodology of signal quantification using dense-array EEG. Preliminary data is shown for three healthy participants and three patients in baseline conditions and for two patients we show the results recorded before and after 10 days rTMS treatment. Our results show differences in sensory gating (P50 suppresion) and a stronger N100-P300 response to rare audio stimulus after the treatment. Moreover we show the value of assessing brain electrical activity from high-density EEG (256 channels) analyzing the results in different regions of interest. However, it is premature and hazardous to assume that rTMS treatment effectiveness in patients with AVH can be assessed using P50 suppression ratio., "Peer Reviewed"

Publisher's version (útgefin grein), Background: New technologies have given rise to an abundance of-omics data, particularly metabolomic data. The scale of these data introduces new challenges for the interpretation and extraction of knowledge, requiring the development of innovative computational visualization methodologies. Here, we present GEM-Vis, an original method for the visualization of time-course metabolomic data within the context of metabolic network maps. We demonstrate the utility of the GEM-Vis method by examining previously published data for two cellular systems-the human platelet and erythrocyte under cold storage for use in transfusion medicine. Results: The results comprise two animated videos that allow for new insights into the metabolic state of both cell types. In the case study of the platelet metabolome during storage, the new visualization technique elucidates a nicotinamide accumulation that mirrors that of hypoxanthine and might, therefore, reflect similar pathway usage. This visual analysis provides a possible explanation for why the salvage reactions in purine metabolism exhibit lower activity during the first few days of the storage period. The second case study displays drastic changes in specific erythrocyte metabolite pools at different times during storage at different temperatures. Conclusions: The new visualization technique GEM-Vis introduced in this article constitutes a well-suitable approach for large-scale network exploration and advances hypothesis generation. This method can be applied to any system with data and a metabolic map to promote visualization and understand physiology at the network level. More broadly, we hope that our approach will provide the blueprints for new visualizations of other longitudinal-omics data types. The supplement includes a comprehensive user's guide and links to a series of tutorial videos that explain how to prepare model and data files, and how to use the software SBMLsimulator in combination with further tools to create similar animations as highlighted in the case studies., This work was funded by the National Institutes of Health (NIH, US, grants 2R01GM070923-13 to AD and U01-GM102098 to LY), the Institute for Systems Biology’s Translational Research Fellowship (JTY), the Landspítali University Hospital Research Fund, the University of Iceland Research Fund, and the Novo Nordisk Foundation through the Center for Biosustainability at the Technical University of Denmark (grant NNF10CC1016517). AD was supported by infrastructural funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Cluster of Excellence EXC 2124 Controlling Microbes to Fight Infections and by the DZIF (German Center for Infection Research). We acknowledge support by Open Access Publishing Fund of University of Tübingen (https://uni-tuebingen.de/de/58988). This work was made possible by the friendly support of yWorks GmbH (https://www.yworks.com) who provided their diagram visualization library yFiles for Java (https://www.yworks.com/products/yfiles-for-java) and assistance during the implementation phase. GEMA-free music licenses for the tutorial videos on SBMLsimulator were provided by Frametraxx UG (https://www.frametraxx.de). We also thank the Google Summer of Code program (https://summerofcode. withgoogle.com) for supporting open-source software development for this project.

Post-print (lokagerð höfundar), We consider the Leader Election Problem in the Signal-to-Interference-plusNoise-Ratio (SINR) model where nodes can adjust their transmission power. We show that in this setting it is possible to elect a leader in two communication rounds, with high probability. Previously, it was known that Θ(log n) rounds were sufficient and necessary when using uniform power, where n is the number of nodes in the network. We then examine how much power control is needed to achieve fast leader election. We show that every 2-round leader election algorithm in the SINR model running correctly w.h.p. requires a power range 2Ω(n) , even when n is known. We complement this with an algorithm that uses power range 2O˜(n)1, when n is known, and 2O˜(n 1.5 ) , when n is not known. We also explore tradeoffs between time and power used, and show that to elect a leader in t rounds, a range of possible power levels of size exp(n 1/Θ(t) ) is sufficient and necessary, This work was funded by Icelandic Research Fund grants 152679-05, 174484-05, AFOSR FA9550-13-1-0042, NSF CCF-1461559 and NSF CCF-0939370., "Peer Reviewed"

Publisher's version (útgefin grein), Films of SiGe nanocrystals (NCs) in oxide have the advantage of tuning the energy band gap by adjusting SiGe NCs composition and size. In this study, SiGe-SiO2 amorphous films were deposited by magnetron sputtering on Si substrate followed by rapid thermal annealing at 700, 800 and 1000 °C. We investigated films with Si:Ge:SiO2 compositions of 25:25:50 vol.% and 5:45:50 vol.%. TEM investigations reveal the major changes in films morphology (SiGe NCs with different sizes and densities) produced by Si:Ge ratio and annealing temperature. XPS also show that the film depth profile of SiGe content is dependent on the annealing temperature. These changes strongly influence electrical and photoconduction properties. Depending on annealing temperature and Si:Ge ratio, photocurrents can be 103 times higher than dark currents. The photocurrent cutoff wavelength obtained on samples with 25:25 vol% SiGe ratio decreases with annealing temperature increase from 1260 nm in SWIR for 700 °C annealed films to 1210 nm for those at 1000 °C. By increasing Ge content in SiGe (5:45 vol%) the cutoff wavelength significantly shifts to 1345 nm (800 °C annealing). By performing measurements at 100 K, the cutoff wavelength extends in SWIR to 1630 nm having high photoresponsivity of 9.35 AW−1., This work was supported by TE Contract no.30/2018 (PN-III-P1-1.1-TE-2016-2050, within PNCDI III), M-ERA.NET PhotoNanoP Contract No. 33/2016, PCE Contract No. 122/2017, PCCDI Contract No. 75/2018, and financed by CNCS-UEFISCDI, and by Romanian Ministry of Research and Innovation through NIMP Core Program PN19-03 (Contract No. 21N/08.02.2019)., "Peer Reviewed"

Publisher's version (útgefin grein), Utilization of fast surrogate models has become a viable alternative to direct handling of full-wave electromagnetic (EM) simulations in EM-driven design. Their purpose is to alleviate the difficulties related to high computational cost of multiple simulations required by the common numerical procedures such as parametric optimization or uncertainty quantification. Yet, conventional data-driven (or approximation) modeling techniques are severely affected by the curse of dimensionality. This is a serious limitation when it comes to modeling of highly nonlinear antenna characteristics. In practice, general-purpose surrogates can be rendered for the structures described by a few parameters within limited ranges thereof, which is grossly insufficient from the utility point of view. This paper proposes a novel modeling approach involving variable-fidelity EM simulations incorporated into the recently reported nested kriging modeling framework. Combining the information contained in the densely sampled low- and sparsely sampled high-fidelity models is realized using co-kriging. The resulting surrogate exhibits the predictive power comparable to the model constructed using exclusively high-fidelity data while offering significantly reduced setup cost. The advantages over conventional surrogates are pronounced even further. The presented modeling procedure is demonstrated using two antenna examples and further validated through the application case studies., This work was supported in part by the Icelandic Centre for Research (RANNIS) under Grant 206606051, and in part by the National Science Centre of Poland under Grant 2018/31/B/ST7/02369.

Publisher's version (útgefin grein), Asthma is one of the most common chronic diseases affecting both children and adults. We report a genome-wide association meta-analysis of 69,189 cases and 702,199 controls from Iceland and UK biobank. We find 88 asthma risk variants at 56 loci, 19 previously unreported, and evaluate their effect on other asthma and allergic phenotypes. Of special interest are two low frequency variants associated with protection against asthma; a missense variant in TNFRSF8 and 3‘ UTR variant in TGFBR1. Functional studies show that the TNFRSF8 variant reduces TNFRSF8 expression both on cell surface and in soluble form, acting as loss of function. eQTL analysis suggests that the TGFBR1 variant acts through gain of function and together with an intronic variant in a downstream gene, SMAD3, points to defective TGFβR1 signaling as one of the biological perturbations increasing asthma risk. Our results increase the number of asthma variants and implicate genes with known role in T cell regulation, inflammation and airway remodeling in asthma pathogenesis., We thank the individuals who participated in this study and the staff at the Icelandic Patient Recruitment Center and the deCODE genetics core facilities. Further to all our colleagues who contributed to the data collection and phenotypic characterization of clinical samples as well as to the genotyping and analysis of the whole-genome association data. This research has been conducted using the UK biobank Resource under Application Number ‘24711’.

Publisher's version (útgefin grein), Design of modern antennas relies-for reliability reasons-on full-wave electromagnetic simulation tools. In addition, increasingly stringent specifications pertaining to electrical and field performance, growing complexity of antenna topologies, along with the necessity for handling multiple objectives, make numerical optimization of antenna geometry parameters a highly recommended design procedure. Conventional algorithms, particularly global ones, entail often-unmanageable computational costs, so alternative approaches are needed. This work proposes a novel method for cost-efficient globalized design optimization of multi-band antennas incorporating the response feature technology into the trust-region framework. It allows for unequivocal allocation of the antenna resonances even for poor initial designs, where conventional local algorithms fail. Furthermore, the algorithm is accelerated by means of Jacobian variability tracking, which reduces the number of expensive finite-differentiation updates. Two real-world antenna design cases are used for demonstration purposes. The optimization cost is comparable to that of local routines while ensuring nearly global search capabilities., This work was supported in part by the Icelandic Centre for Research (RANNIS) under Grant 206606051, and in part by the National Science Centre of Poland under Grant 2017/27/B/ST7/00563., "Peer Reviewed"

Publisher's version (útgefin grein), Optimization-based parameter tuning has become an inherent part of contemporary antenna design process. For the sake of reliability, it is typically conducted at the level of full-wave electromagnetic (EM) simulation models. This may incur considerable computational expenses depending on the cost of an individual EM analysis, the number of adjustable variables, the type of task (local, global, single-/multi-objective optimization), and the constraints involved. For these reasons, utilization of conventional algorithms is often impractical. This paper proposes a novel gradient-based algorithm with numerical derivatives for expedited antenna optimization. The improvement of computational efficiency is obtained by employing a rank-one Broyden formula and restricting finite differentiation sensitivity updates to the principal directions of the Jacobian matrix, i.e., those corresponding to the most significant changes of the antenna responses. Comprehensive numerical validation carried out using three wideband antennas indicates that the presented methodology offers considerable savings of sixty percent with respect to the reference trust-region algorithm. At the same time, virtually no degradation of the design quality is observed. Furthermore, algorithm reliability is greatly improved (while offering comparable computational efficiency) over the recent state-of-the-art accelerated gradient-based procedures., The Icelandic Centre for Research (RANNIS) Grant 174114051, and in part by the National Science Centre of Poland Grant 2015/17/B/ST6/01857., "Peer Reviewed"

Publisher's version (útgefin grein), In this paper, a multiple-input-multiple-output (MIMO) antenna featuring circular polarization diversity, and designed on a common coplanar ground is presented. The proposed antenna design utilizes a coplanar waveguide (CPW) feeding technique with three parallel coplanar ground planes, and two feedlines in-between. For circular polarization (CP), quasi-loops are created by etching slots on the outermost ground planes. With this configuration, circular polarization diversity is induced in the MIMO antenna with the left-hand CP (LHCP) from one antenna and the right-hand CP (RHCP) from the other. The total footprint of the antenna radiator is only 0.78 lambda(0) x 0.55 lambda(0) = 0.42 lambda(2)(0). Experimental results show perfectly overlapping impedance and axial ratio bandwidths of 39.3% (4.5 GHz to 6.7 GHz). In addition, average in-band isolation vertical bar S-21 vertical bar, This work was supported in part by the Abu Dhabi Department of Education and Knowledge (ADEK) Award for Research Excellence, in 2019, under Grant AARE19-245, in part by The Icelandic Centre for Research (RANNIS) under Grant 206606051, and in part by the National Science Centre of Poland under Grant 2017/27/B/ST7/00563., "Peer Reviewed"

Publisher's version (útgefin grein), Uncertainty quantification is an important aspect of engineering design, also pertaining to the development and performance evaluation of antenna systems. Manufacturing tolerances as well as other types of uncertainties, related to material parameters (e.g., substrate permittivity) or operating conditions (e.g., bending) may affect the antenna characteristics. In the case of narrow- or multi-band antennas, this usually leads to frequency shifts of the operating bands. Quantifying these effects is imperative to adequately assess the design quality, either in terms of the statistical moments of the performance parameters or the yield. Reducing the antenna sensitivity to parameter deviations is even more essential when increasing the probability of the system satisfying the prescribed requirements is of concern. The prerequisite of such procedures is statistical analysis, normally carried out at the level of full-wave electromagnetic (EM) analysis. While necessary to ensure reliability, it entails considerable computational expenses, often prohibitive. Following the recently fostered concept of constrained modeling, this paper proposes a simple technique for rapid surrogate-assisted yield optimization of narrow- and multi-band antennas. The keystone of the approach is an appropriate definition of the optimization domain. This is realized by considering a few pre-optimized designs that represent the directions of the major changes of the antenna resonant frequencies and operating bands. Due to a small volume of such a domain, an accurate replacement model can be established therein using a small number of training samples, and employed to improve the antenna yield. Verification results obtained for a ring-slot antenna, a dual-band and a triple-band uniplanar dipoles indicate that the optimization process can be accomplished at low cost of a few dozen of EM simulations: 62, 74 and 132 EM simulations, respectively. Result reliability is validated through comparisons with EM-based Monte Carlo simulations., This work was supported in part by the Icelandic Centre for Research (RANNIS) under Grant 206606051, in part by the National Science Centre of Poland under Grant 2017/27/B/ST7/00563, and in part by the Abu-Dhabi Department of Education and Knowledge (ADEK) Award for Research Excellence, in 2019, under Grant AARE19-245., "Peer Reviewed"

Publisher's version (útgefin grein), The paper proposes a novel framework for accelerated re-design (dimension scaling) of antenna structures using inverse surrogates. The major contribution of the work is a sensitivity-based model identification procedure, which permits a significant reduction of the number of reference designs required to render the surrogate. Rigorous formulation of the approach is supplemented by its comprehensive numerical validation using a triple-band uniplanar dipole antenna and a dual-band monopole antenna re-designed with respect to operating frequencies as well as the substrate parameters (thickness and dielectric permittivity). It is demonstrated that—for the considered test cases—the reliable inverse model can be set up using a significantly smaller (by a factor of three) number of reference points as compared to the original version of the method, whereas the dimension scaling process itself requires up to four EM simulations of the antenna structure., This work was supported in part by the Icelandic Centre for Research (RANNIS) under Grant 174573051, and in part by the NationalScience Centre of Poland under Grant 2017/27/B/ST7/00563.

Publisher's version (útgefin grein), Design of contemporary microwave components is & x2014;in a large part & x2014;based on full-wave electromagnetic (EM) simulation tools. The primary reasons for this include reliability and versatility of EM analysis. In fact, for many microwave structures, notably compact components, EM-driven parameter tuning is virtually imperative because traditional models (analytical or network equivalents) are unable to account for the cross-coupling effects, strongly present in miniaturized layouts. At the same time, the cost of simulation-based design procedures may be significant due to a typically large number of evaluations of the circuit at hand involved. In this paper, a novel approach to expedited design closure of compact microwave passives is presented. The proposed procedure incorporates available designs (e.g., existing from the previous design work on the same structure) in the form of the kriging interpolation models, utilized to yield a reasonable initial design and to accelerate its further refinement. An important component of the framework is an iterative correction procedure that feeds the accumulated discrepancies between the target and the actual design objective values back to the kriging surrogate to produce improved predictions. The efficacy of our methodology is demonstrated using two miniaturized impedance matching transformers with the optimized designs obtained at the cost of a few EM simulations of the respective circuits. The relevance of the iterative correction is corroborated through the comparative studies showing its superiority over rudimentary gradient-based refinement., This work was supported in part by the Icelandic Centre for Research (RANNIS) under Grant 174114051, and in part by the National Science Centre of Poland under Grant 2015/17/B/ST6/01857., "Peer Reviewed"

The postural control system regulates the ability to maintain a stable upright stance and to react to changes in the external environment. Although once believed to be dominated by low-level reflexive mechanisms, mounting evidence has highlighted a prominent role of the cortex in this process. Nevertheless, the high-level cortical mechanisms involved in postural control are still largely unexplored. The aim of this thesis is to use electroencephalography, a widely used and non-invasive neuroimaging tool, to shed light on the cortical mechanisms which regulate postural control and allow balance to be preserved in the wake of external disruptions to one’s quiet stance. EEG activity has been initially analysed during a well-established postural task - a sequence of proprioceptive stimulations applied to the calf muscles to induce postural instability – traditionally used to examine the posturographic response. Preliminary results, obtained through a spectral power analysis of the data, highlighted an increased activation in several cortical areas, as well as different activation patterns in the two tested experimental conditions: open and closed eyes. An improved experimental protocol has then been developed, allowing a more advanced data analysis based on source reconstruction and brain network analysis techniques. Using this new approach, it was possible to characterise with greater detail the topological structure of cortical functional connections during the postural task, as well as to draw a connection between quantitative network metrics and measures of postural performance. Finally, with the integration of electromyography in the experimental protocol, we were able to gain new insights into the cortico-muscular interactions which direct the muscular response to a postural challenge. Overall, the findings presented in this thesis provide further evidence of the prominent role played by the cortex in postural control. They also prove how novel EEG-based brain network analysis techniques can be a valid tool in postural research and offer promising perspectives for the integration of quantitative cortical network metrics into clinical evaluation of postural impairment., Kerfi stöðustjórnunar er afturvirkt stýrikerfi sem vinnur stöðugt að því að viðhalda uppréttri stöðu líkamans og bregðast við ójafnvægi. Vaxandi þekking á undanförnum árum hefur lýst því að úrvinnsla þessara upplýsinga á sér stað á öllum stigum miðtaugakerfisins, þá sérstaklega barkarsvæði heilahvela. Engu að síður, er nákvæmu hlutverk heilabarkar við stöðustjórnun enn óljóst að mörgu leyti. Tilgangur þessa verkefnis var að rannsaka nánar hlutverk heilabarkar við truflun og áreiti á kerfi stöðustjórnarinnar, með notkun hágæða heilarafrits (EEG). Við byrjuðum á því að mæla heilarit einstaklinga meðan á þekktri líkamsstöðu-æfingu stóð, til þess að skoða svörun líkamans við röð titringsáreita sem beitt var á kálfavöðvana til að framkalla óstöðugleika. Bráðabirgðaniðurstöður fengnar með PSD-aðferð (power spectral analysis) leiddu í ljós aukna virkni á ákveðnum svæðum í heilaberki og sérstakt viðbragðsmynstur við að framkvæma æfinguna, annars vegar með lokuð augu og hins vegar opin augu. Rannsókn okkar hélt áfram með nýrri og þróaðari tækni sem gerði okkur kleift að framkvæma fullkomnari greiningaraðferðir til að túlka, greina og skilja merki frá heilaritnu. Með fullkomnari greiningaraðferðum var hægt að lýsa með nákvæmari hætti staðfræðilega uppbyggingu starfrænna tenginga í heilaberki meðan á líkamsstöðu æfingunni stóð, sem og að draga tengsl á milli megindlegra netmælinga og mælinga á líkamsstöðu. Að lokum bætist við vöðvarafritsmæling við aðferðafræðina, sem gaf okkur innsýn inn í samskipti heilabarka og vöðvana sem stýra vöðvaviðbrögðum og viðhalda líkamsstöðu við utanaðkomandi áreiti. Á heildina litið gefa niðurstöðurnar sem settar eru fram í þessari ritgerð enn sterkari vísbendingar um það áberandi hlutverk sem heilabörkurinn gegnir við stjórnun líkamsstöðu. Niðurstöðurnar sanna einnig hvernig ný aðferð á greiningu á tengslaneti heilans sem byggir á heilariti getur verið gilt tæki í líkamsstöðu rannsóknum og er nytsamlegt tól fyrir mælingar á heilakerfisneti í klínískt mat á skerðingu líkamsstöðu.

Background: Repetitive transcranial magnetic stimulation (RTMS) has been suggested as a possible therapeutic alternative for patients with schizophrenia (SCZ) and treatment-resistant auditory verbal hallucinations (AVH). The aim of the studies presented here was to investigate how RTMS affects clinical symptoms, electroencephalographic responses, and brain functional networks. We suspected improvement of symptoms accompanied by changes in EEG activity, event-related potentials, and sensory gating. Subjects and methods: Ten patients with schizophrenia (mean age 32.4, SD = 6.85, 7m, 3f) and six healthy controls (mean age 30.3, SD = 7.5, 4m, 2f) participated in this study. Nine patients were on antipsychotic medication. The patients were randomly selected into two groups, the treatment group (TG) and the control group (CG). The active low-frequency 1Hz RTMS was delivered in ten daily sessions of 900 pulses at two different EEG locations: T3-P3 (TG) and Cz (CG). Clinical symptoms were investigated with psychometric scales like Quality of Life (QoL), Depression Anxiety Stress Scales (DASS), and Psychotic Symptom Rating Scale with Auditory Hallucinations Subscale (PSYRATS AHS). The neurophysiological tests employed were cortical and cutaneous silent period, mid-latency auditory evoked potentials (P50, N100, P200) using a paired click paradigm, P300 obtained with an auditory oddball paradigm, and the cognitively driven auditory-motor task (AMT). Time, frequency domains, and functional network organization of different neurophysiological markers were analyzed. P300 oscillatory activity was analyzed with EEG source connectivity (e.g., participation coefficient) and for the auditory-motor task-induced oscillations, we used network integration parameters of graph theory (i.e., characteristic path length - CPL and small worldness - SW). The patient's results obtained after the treatment (T2) were compared with data obtained at baseline condition (T1) and with data from the third group of healthy controls (HC). Results: There were no significant changes between TG and CG on QoL, DASS, and PSYRATS AHS scores or neurophysiological data after the RTMS treatment. We also calculated pre-post RTMS changes for all patients. N100 showed the most marked changes after RTMS in left temporoparietal region, from -0.57 μV (SD 0.97) to -2.39 μV (SD 1.59), (p = 0.006, η2 = 0.346) and in medial posterior region (p = 0.038, η2 = 0.218) suggesting a modulation of this marker over both stimulation sites. After RTMS, N100-P300 voltage increased for six patients, two in TG and four in CG, but also decreased in patients from TG who showed the best clinical outcome. The EEG power spectral density (PSD) during the auditory oddball paradigm increased in T2, mainly for the alpha band and beta band globally, for six subjects, two in TG and four in CG. The connectivity results for the frequent stimuli of the auditory oddball paradigm showed increased network segregation during T2 for the beta band, in seven patients, four in CG, and three in TG. The study revealed that patients with schizophrenia exhibit higher gamma PSD in a period between two auditory commands of AMT, compared to HC, which was modified by RTMS without being significant. The change was visible, locally, over the left temporoparietal region, when the task was done with the non-dominant hand, showing that during this condition, gamma synchronization is a marker of “neural effort” and workload during the working memory-related time and not during the auditory or motor cortical activation. Graph theory analyzed for low-gamma EEG activity elicited in between the auditory stimuli, an epoch of the auditory-motor task we called “non-cortical activation” and which is related to the working memory, showed a decreased SW index after RTMS when the task was performed with the non-dominant hand. This SW effect observed in the patients was similar to that of the HC group. Kendall's tau-b correlation showed a strong, negative correlation between the SW index of low-gamma phase oscillations and PSYRATS AHS scores in T1, which was statistically significant (τb = −0.788, p = 0.032). After RTMS (T2) the correlation was strongly positive (τb = 0.733, p = 0.039). Discussion: The sample size of this study was small to achieve TG-CG statistical significance (e.g., PSYRATS AHS pre-calculated N was 16). Individual data showed controversial results, sometimes with the improvement of AVH severity and neurophysiological data in patients treated at the Cz EEG location. N100 from the paired click paradigm showed the most marked changes at the left temporoparietal region. P300 was performed with a passive auditory oddball paradigm by “automatic” discrimination between two tones without asking the subject to move the finger or count the target stimuli. The findings we obtained with P300 amplitude, which in most cases decreased after RTMS, might be in direct relation to a habituation effect, which is seen in healthy subjects (Polich, 1989). Conclusion: Based on the patient ́s clinical evaluations and all the neurophysiological measurements presented in the studies of this thesis we cannot affirm that left temporoparietal (T3-P3) RTMS is more effective than vertex (Cz) RTMS in patients with schizophrenia and auditory verbal hallucinations. Some interesting neurophysiological observations were made, particularly changes of N100 amplitude at the left temporoparietal region and low gamma activity during the period in between auditory commands of a cognitively driven task. N100 amplitude measured from a paired click paradigm and low gamma activity measured in-between auditory stimuli of AMT performed with the non-dominant hand might be of interest to assess the neuromodulatory aftereffects of RTMS in patients with SCZ and AVH. The small-world network of low gamma activity showed a significant main effect of the condition (AMT and resting state) for HC and SCZ-T2 suggesting that RTMS might have influenced the network by restoring the SW index. Further, studies with a multimodal neurophysiological approach are necessary to assess RTMS effectiveness for patients with SCZ and AVH., Bakgrunnur: Undanfarin ár hefur raðsegulörvun (RTMS) verið sífellt meira notuð sem meðferðarúrræði fyrir sjúklinga með geðklofa (SCZ) og meðferðarónæmar heyrnar- og talofskynjanir (AVH). Markmið rannsóknanna sem kynntar eru hér var að kanna hvernig RTMS hefur áhrif á klínísk einkenni, raflífeðlisfræðilega svörun og starfsemi heilans. Áætlað var að jákvæðar taugalífeðlisfræðilegar breytingar myndu sjást samfara bættum klínískum einkennum í kjölfar meðferðar. Aðferðir: Tíu sjúklingar með geðklofa (meðalaldur 32,4, SD = 6,85, 7 kk, 3 kvk) og sex heilbrigðir einstaklingar (meðalaldur 30,3, SD = 7,5, 4 kk, 2 kvk) tóku þátt í þessari rannsókn. Níu af tíu sjúklingum voru á geðrofslyfjum. Sjúklingarnir voru valdir af handahófi í tvo hópa, meðferðarhóp (TG) og viðmiðunarhóp (CG). Hamlandi, lágtíðni (1Hz) RTMS var veitt í tíu daglegum lotum (900 púlsar í hvert skipti) á tveimur mismunandi heilaritasstöðum: T3-P3 (TG) og Cz (CG). Klínísk einkenni voru metin með eftirfarandi sálfræðilegum kvörðum: Quality of Life (QoL), Depression Anxiety Stress Scales (DASS), og Psychotic Symptom Rating Scale with Auditory Hallucinations Subscale (PSYRATS AHS). Taugalífeðlisfræðilegu prófin sem notuð voru könnuðu; 1) þögla tímabil heila og mænu, og 2) Heyrnar-hrifrit (early and mid-latency ERPs), þar sem svörun við pöruðum tónum (e. paired click paradigm) var könnuð (P50, N100, P200 bylgjurnar) annars vegar, og svörun á frávikstónaprófi (e. oddball-task) til að kanna P300 bylgjuna hins vegar. Auk þess var annað próf sem kannaði svörun eftir fyrirmælum (e. auditory-motor task, (AMT)). Tími, tíðnisvið og starfræn netkerfi voru greind. Uppsprettu tengingar heilaritsins (e. EEG source connectivity) voru metnar fyrir P300 bylgjuna (t.d. participation coefficient) og AMT var greint út frá graffræði (e. Graph theory), þar sem tengsl milli heilasvæða voru skoðuð (t.d. Characteristic path length (CPL) og small worldness (SW)). Niðurstöður sem fengust eftir meðferð (T2) voru bornar saman við niðurstöður sem fengust fyrir meðferð (T1) og gögnum frá þriðja hópi heilbrigðra einstaklinga (HC). Niðurstöður: Engar marktækar breytingar sáust á milli TG og CG á QoL, DASS og PSYRATS AHS svörunar né taugalífeðlisfræðilegum mælingum eftir RTMS meðferðina. Einnig voru reiknaðar út breytingar á taugalífeðlisfræðilegum mælingum og spurningalistum fyrir og eftir RTMS fyrir alla sjúklinga sem einn hópur. Þar sýndi N100 mest áberandi breytingar eftir RTMS á mörkum vinstra gagnauga- og hvirfilblaðs, frá -0,57 μV (SD 0,97) í -2,39 μV (SD 1,59), (p = 0.006, η2 = 0.346) og á miðlægu hvirfilblaði (p = 0.038, η2 = 0.218) sem bendir til þess að heilastarfsemi hafi breyst nálægt báðum örvunarstöðum. Eftir RTMS jókst N100-P300 spenna hjá sex sjúklingum, tveimur í TG og fjórum í CG, en lækkaði einnig hjá sjúklingum úr TG sem sýndu bestu klínísku útkomuna. Heildar aflrófsþéttleiki (e. power spectral density, (PSD)) á meðan á frávikstónaprófi stóð jókst í T2, aðallega fyrir alfa-bandið og beta-bandið yfir allt höfuðið, hjá sex einstaklingum, tveimur í TG og fjórum í CG. Niðurstöður netkerfa-tenginga (e. connectivity) fyrir tíð áreiti í frávikstónaprófinu sýndu aukinn aðskilnað við T2 athugun fyrir beta-bandið hjá sjö sjúklingum, fjórum í CG og þremur í TG. Rannsóknin leiddi í ljós að PSD svið hjá sjúklingum með geðklofa hækkaði í gamma-bandinu á tímabilinu milli tveggja hljóðskipana í AMT prófinu, samanborið við HC, sem var breytt án þess að vera marktækt. Breytingin var sýnileg og staðbundin yfir mörkum vinstra gagnauga- og hvirfilblaðs, þegar verkefnið var unnið með víkjandi hendi. Það bendir til þess að í þessu ástandi gæti gamma-samstilling verið merki um „taugaátak“eða vinnuálag þegar vinnsluminni er virkt, en ekki á meðan á heyrnar- eða hreyfibarkarvirkjun stendur. Graffræði var greind með tilliti til lág-gamma heilavirkni, á milli áreita í AMT verkefninu sem við kölluðum „non-cortical activation“, sem tengist vinnsluminni. Sú greining sýndi lækkuð SW gildi eftir RTMS þegar verkefnið var framkvæmt með víkjandi hendi. Þessi SW áhrif sem sáust hjá sjúklingunum voru svipuð og hjá HC hópnum. Tau-b fylgni Kendalls sýndi sterka, neikvæða fylgni á milli SW gilda lág-gamma fasa-sveiflna og PSYRATS AHS svörunar í T1, sem var tölfræðilega marktæk (τb = -0,788, p = 0,032). Eftir RTMS (T2) sást sterk jákvæð fylgni þar á milli (τb = 0,733, p = 0,039). Umræða: Þátttakendur í þessari rannsókn voru of fáir til að ná fram marktækum mun á milli hópanna TG-CG (t.d. var hópastærð fyrir PSYRATS AHS fyrirfram reiknuð fyrir 16 einstaklinga). Niðurstöður á einstaklingsgrunni sýndu umdeildar niðurstöður, þar sem meðal annars klínísk einkenni og taugalífeðlisfræðileg svörun batnaði hjá sjúklingum sem voru meðhöndlaðir á Cz svæðinu. Í verkefni þar sem tónapör voru lögð fyrir þátttakendur, sýndi N100 bylgjan aðlögun á mörkum gagnauga- og hvirfilblaðs eftir meðferð. P300 bylgjan var einnig mæld, þar sem tveir mismunandi tónar heyrðust, og annar þeirra var sjaldgæfari en hinn. Verkefnið var “óvirkt” í þeim skilningi að það krafðist engrar virkrar svörunar. Niðurstöðurnar úr greiningu sveifluvíddar P300 sem í flestum tilfellum minnkaði eftir RTMS, gætu verið í beinu sambandi við vanaáhrif (e. habituation) sem sjást hjá heilbrigðum einstaklingum (Polich, 1989). Ályktun: Niðurstöður rannsóknarinnar geta ekki með óyggjandi hætti sagt til um hvort RTMS sé áhrifarík meðferð fyrir sjúklinga með geðklofa og meðferðarþráar heyrnarofskynjanir. Þrátt fyrir það bar á áhugaverðum taugalífeðlisfræðilegar niðurstöðum. Ber þá helst að nefna breytingar á N100 sveifluvídd á mótum vinstra gagnauga- og hvirfilblaðs og lág-gammavirkni á tímabilinu á milli fyrirmæla í AMT. Áhugavert væri í framtíðinni að kanna frekar áhrif RTMS hjá þessum sjúklingahóp hvað varðar sveifluvídd N100 þar sem tóna-pör voru lögð fyrir (e. Paired click paradigm) og lág-gamma virkni mæld á milli fyrirmæla

Publisher's version (útgefin grein), Silicon nanowires (SiNWs) are known to exhibit a large piezoresistance (PZR) effect, making them suitable for various sensing applications. Here, we report the results of a PZR investigation on randomly distributed and interconnected vertical silicon nanowire arrays as a pressure sensor. The samples were produced from p-type (100) Si wafers using a silver catalyzed top-down etching process. The piezoresistance response of these SiNW arrays was analyzed by measuring their I-V characteristics under applied uniaxial as well as isostatic pressure. The interconnected SiNWs exhibit increased mechanical stability in comparison with separated or periodic nanowires. The repeatability of the fabrication process and statistical distribution of measurements were also tested on several samples from different batches. A sensing resolution down to roughly 1 mbar pressure was observed with uniaxial force application, and more than two orders of magnitude resistance variation were determined for isostatic pressure below atmospheric pressure., Reykjavík University

Publisher's version (útgefin grein), Butler matrices represent a popular class of feeding networks for antenna arrays. Large dimensions and the lack of flexibility in terms of achievable output phase difference make conventional Butler structures of limited use for modern communication devices. In this work, a com-pact planar 4×4 matrix with non-standard relative phase shifts of –30,150, –120, and 60° has been proposed. The structure is designed to operate at the centre frequency of 2.45 GHz. Small dimensions of 31.3×22.9 mm make it useful for Internet of Things applications. The structure operates from 2.35 to 2.55 GHz, which covers the industrial, scientific and medical bandwidth. At the centre frequency, the measured amplitude and phase imbalance are 1.65 dB and±4.3°, respectively. The proposed circuit has been compared to the state-of-the-art structures from the literature., This work was supported in part by National Centre for Research and Development Grant NOR/POLNOR/HAPADS/ 0049/2019-00, by National Science Centre of Poland Grant 2017/27/B/ST7/00563, and by Icelandic Centre for Research (RANNIS) Grant 206606051.

Lidar systems have been used widely to measure wind profiles and atmospheric aerosols. The scanning Doppler lidars operated by the Icelandic Meteorological Office can provide continuous measurements of the wind velocity and direction based on the Doppler effect, from the emitted signal, as well as the backscatter coefficient and depolarization ratio for retrieving aerosol properties. In this project, we investigate the use of Doppler lidars in Iceland, especially for enhancing aviation safety. The project was divided into three main tasks have been conducted: 1) atmospheric turbulence measurements; 2) airborne aerosol detection; 3) real-time lidar signal classification with machine learning algorithms. In the first task, an algorithm was developed based on the Kolmogorov theory to retrieve eddy dissipation rate, as an indicator of turbulence intensity, from lidar wind measurements. The method was tested on two cases from 2017. In the second task, the Doppler lidar was used in combination with ceilometers, a sun-photometer and other instruments, to detect aerosols, including dust and volcanic ash in Iceland. In the third task, both supervised and unsupervised machine learning algorithms were developed to identify the noise signal and classify the lidar measurements, with the aim of providing real-time lidar signal classification for potential end-users. The results indicate that the Doppler lidar can significantly improve aviation safety and complement meteorological measurements by detecting atmospheric turbulence or volcanic ash clouds in Iceland., Vind- og agnasjár (e. lidar) hafa verið notaðar víða til að mæla vindsnið og nema svifryk og aðrar agnir í lofthjúpnum. Veðurstofa Ísland á tvo Doppler agnasjár sem geta veitt samfelldar mælingar á vindhraða og -stefnu, byggðar á Dopplerhrifa, og endurkastsstuðul og tvípólunarhlutfall (e. depolarization ratio) agna. Í þessu verkefni var könnuð notkun Doppler agnasjár á Íslandi til að auka flugöryggi. Verkefninu var skipt niður í þrjá verkþætti: i) ókyrrðarmælingar í jaðarlaginui; ii) svifryk og aðrar agnir í lofthjúpnum; iii) rauntímaflokkun agna með vélrænu námi (e. machine learning). Í verkþætti i) var þróuð reikniaðferð byggð á kenningu Kolmogorov til að meta sveipeyðingarákefð (e. eddy dissipation rate) frá vindmælingum, sem vísbendingu um ókyrrðarstyrk Aðferðin var prófuð í tveimur tilvikum frá árið 2017. Í verkþætti ii) voru gögn frá Doppler agnasjánni notuð, með gögnum úr skýjahæðamæli, sólarljósamæli og öðrum tækjum til að greina svifryk, þar með talið ryk og eldfjallaösku á Íslandi. Í verkþættii iii) var þróaðvélrænt nám, bæði undir eftirliti og án eftirlits, til að bera kennsl á suð og flokka mælingarnar með það að markmiði að veita rauntímaliðaflokkun fyrir hugsanlega notendur. Niðurstöðurnar benda til þess að Doppler vind- og agnasjá geti bætt verulega flugöryggi og verið góð viðbót við hefðbundnari veðurmælingar á Íslandi, með því að greina ókyrrð og öskuí lofti., ISAVIA

Paper I in this thesis is under revision and may go through modification before official publication., Á undanförnum árum hafa sviðin endurnýjunar og tilfærslu lækningar vakið sífellt meiri áhuga vegna möguleikanna sem í þeim felast er varða nýjungar í læknavísindum. Innan þeirra má finna ýmis tól sem talin eru vera lykilatriði þegar kemur að því að finna og þróa ný meðferðarúrræði, og er eitt þessara tóla notkun mesenkýmal stofnfrumna (MSF). MSF hafa verið rannsakaðar m.t.t. ýmissa þátta þ.á.m. getu þeirra til að bæta endurnýjun beina og endurbyggingu beinvefs. Þrátt fyrir margvíslegar rannsóknir og meðfylgjandi framfarir í áttina að mögulegri klínískri notkun er margt sem er enn óljóst er varðar virkni og möguleika þessara frumna. Nákvæm og skipulögð rannsókn ásamt tiltölulega nákvæmum tölvulíkönum sem geta hermt eftir efnaskiptabreytingum og líkt eftir samfylgjandi svipgerðum gætu verið leiðir til að stoppa upp í núverandi göt í þekkingu hvað varðar efnaskiptabreytingar, frá tjáningu gena til framleiðslu próteina, ásamt því að veita möguleika á tilgátuprófunum án meðfylgjandi kostnaðar. Markmið verkefnisins sem hér er kynnt var að rannsaka efnaskiptabreytingar í mennskum MSF við beinsérhæfingu til að reyna að skilgreina mögulega efnaskipta fasa sem beinsérhæfingartímabilið væri samsett úr og búa til in silico módel byggð á genatengdum upplýsingum til að líkja eftir breytingunum. Í fyrsta hluta þessa verkefnis var notast við innan- og utanfrumu metabolómísk gögn til að skilgreina möguleg mismunandi stig beinsérhæfingar og hvaða efnaskiptabrautir geta legið þar að baki. Eftir greiningu gagna var lögð var fram tilgáta um tilveru þriggja mismunandi fasa og merkt innanfrumu gögn bentu til dvínandi virkni í glýkólýsu í gegnum sérhæfingartímann á sama tíma og aukningu gætti í hvatbera tengdum orkugefandi ferlum eftir því sem leið á. Þessar niðurstöður geta hjálpað með að finna tímapunkta sem eru af sérstökum áhuga er varðar kortlagningu mikilvægra efnaskiptabreytinga. Í öðrum hluta verkefnisins var notast við utanfrumu metabólómísk gögn sem safnað var frá mennskum MSF einangruðum úr beinmerg sem ræktaðar voru við venjulega skiptingu, fitu- og beinsérhæfingu, og þau notuð ásamt sértækum tilraunatengdum gögnum til að búa til þrjú sambærileg in silico módel, þau fyrstu sinnar gerðar, er líkja eftir efnaskiptabreytingum þessara þriggja frumugerða fyrstu 7 daga ræktunar. Módelin voru öll líffræðilega möguleg og sýndu af sér öll helstu einkennandi hvörf sem virk. Við greiningu og samanburð á módelunum fundust helstu breyttu undirkerfi og efnaskiptaferlar er voru einkennandi fyrir hverja frumugerð fyrir sig. Í tilviki frumna í venjulegri skiptingu voru breytt kerfi mjög fjölbreytt sem endurspeglar þær fjölbreyttu kröfur sem fruma þarf að uppfylla við að búa til annað eintak af sér, í tilviki fitusérhæfingar var nýmyndun og oxun fitusýra hvað mest áberandi og oxun fitusýra ásamt flutnings hvörfum einkenndu beinsérhæfingu. Þessi módel má nota til að sigta úr og setja upp ákjósanlegar tilraunir til að besta beinsérhæfingu og með breytingum mætti búa til sjúkdómsmódel til að líkja eftir beinþynningu. Í þriðja þætti verkefnisins sem hér er kynnt hafa verið tekið saman þau margvíslegu einkenni og fjölmörgu möguleikar er felast í MSF sem tóli til að nýta í endurnýjunar lækningum og vefjaverkfræði og hvernig, með notkun in silico efnaskiptamódela byggðum á genaupplýsingum, þá möguleika mætti þróa áfram á skilvirkari og hraðari máta samtímis því að lækka tilraunatengdan kostnað. Þetta verkefni hefur lagt sitt af mörkum er kemur að því að minnka núverandi eyðu þekkingar er varðar efnaskiptabreytingar er eiga sér stað í gegnum beinsérhæfingu mennskra MSF og hefur komið með að borðinu ný tól sem geta nýst til frekari rannsókna á sama sviði meðfram því að geta gert þær skilvirkari og hagkvæmari. hefur komið með að borðinu ný tól sem geta nýst til frekari rannsókna á sama sviði meðfram því að geta gert þær skilvirkari og hagkvæmari., In recent years the fields of regenerative and translational medicine have become the subjects of significantly growing interest due to their offer of previously unimaginable therapeutics. Within these fields are several novel tools believed to hold the keys to furthering existing and new developments and one of those tools is human mesenchymal stem cells. One of the applications hMSCs have been studied for is enhanced osteogenic regeneration or reconstruction of new bone tissue. Although various studies have been performed and some strides been made towards a plausible clinical application there is still lot left to be discovered. A methodical studying and relatively detailed in silico genome scale metabolic modelling occurring changes and the accompanying metabolic phenotypes could provide a means to fill in the existing knowledge gaps (from the protein level all the way to the genomic level) and, additionally, a means to perform hypotheses testing with a significant reduction when it comes to the accompanying cost. The objective of this thesis was to study the metabolomic changes in hMSCs during osteogenic differentiation using original transcriptomic, intracellular and extracellular metabolomic data in order try and define possible metabolic stages over the course of the differentiation and use genome scale network reconstruction to create in silico models. In the first part of this work extracellular and intracellular data were used to define possible stages to osteogenic differentiation and hypothesise which pathways may characterise the different metabolic phenotypes. Three stages were suggested based on the data and labelled intracellular metabolomics indicated a decrease in glycolytic dependencies throughout the differentiation period with an increase in mitochondria related energy producing functions as the osteogenesis progressed. This will help focus specific time points of interest and relevance when it comes to mapping the significant metabolomic changes. In the second part of this work extracellular metabolomic data collected from BM-hMSCs during proliferation, adipogenic and osteogenic differentiation was used along with experimentally specific data to create three directly comparable genome scale metabolic models, two of which have no comparable predecessors, for those cell lineages during the first 7 days of cell culture. Models were biologically feasible and showed all lineage specific characteristic reactions as active. By analysis and comparison, the various enriched subsystems and pathways most significant for each lineage were found. Results were varied for proliferating cells, which matches that they have to synthesise various metabolites and substances to expand, whilst fatty acid oxidation and fatty acid synthesis was most prominent in adipogenesis with fatty acid oxidation as well as transport reactions characteristic for osteogenesis. These models can be used for model-driven experimental design to engineer osteogenesis and, with modifications, to create disease model for osteoporosis. In the third part presented we summarized the various characteristics and possibilities that lie in using MSCs as a tool in tissue engineering and regenerative medicine and how, via implementation of genome scale metabolic model reconstruction, their possibilities could possibly be taken much further in a faster, more methodical manner while reducing the related experimental cost. To summarise, this work has provided real strides when it comes to closing the existing gap regarding metabolomic changes during differentiation of hMSCs as well as providing novel tools that can be used to make further studies more efficient and cost effective., The Icelandic research fund (grant number 217005).

Publisher's version (útgefin grein), The availability of engineered biological tissues holds great potential for both clinical applications and basic research in a life science laboratory. A prototype standalone perfusion/compression bioreactor system was proposed to address the osteogenic commitment of stem cells seeded onboard of 3D chitosan-graphene (CHT/G) templates. Testing involved the coordinated administration of a 1 mL/min medium flow rate together with dynamic compression (1% strain at 1 Hz; applied twice daily for 30 min) for one week. When compared to traditional static culture conditions, the application of perfusion and compression stimuli to human bone marrow stem cells using the 3D CHT/G template scaffold induced a sizable effect. After using the dynamic culture protocol, there was evidence of a larger number of viable cells within the inner core of the scaffold and of enhanced extracellular matrix mineralization. These observations show that our novel device would be suitable for addressing and investigating the osteogenic phenotype commitment of stem cells, for both potential clinical applications and basic research., "Peer Reviewed"

Publisher's version (útgefin grein)., Analysis of sequence diversity in the human genome is fundamental for genetic studies. Structural variants (SVs) are frequently omitted in sequence analysis studies, although each has a relatively large impact on the genome. Here, we present GraphTyper2, which uses pangenome graphs to genotype SVs and small variants using short-reads. Comparison to the syndip benchmark dataset shows that our SV genotyping is sensitive and variant segregation in families demonstrates the accuracy of our approach. We demonstrate that incorporating public assembly data into our pipeline greatly improves sensitivity, particularly for large insertions. We validate 6,812 SVs on average per genome using long-read data of 41 Icelanders. We show that GraphTyper2 can simultaneously genotype tens of thousands of whole-genomes by characterizing 60 million small variants and half a million SVs in 49,962 Icelanders, including 80 thousand SVs with high-confidence., We are grateful to our colleagues from deCODE genetics / Amgen Inc. for their contributions. We also wish to thank all research participants who provided a biological sample to deCODE genetics.

Publisher's version (útgefin grein), Multilayer structures comprising of SiO2/SiGe/SiO2 and containing SiGe nanoparticles were obtained by depositing SiO2 layers using reactive direct current magnetron sputtering (dcMS), whereas, Si and Ge were co-sputtered using dcMS and high-power impulse magnetron sputtering (HiPIMS). The as-grown structures subsequently underwent rapid thermal annealing (550-900 degrees C for 1 min) in N-2 ambient atmosphere. The structures were investigated using X-ray diffraction, high-resolution transmission electron microscopy together with spectral photocurrent measurements, to explore structural changes and corresponding properties. It is observed that the employment of HiPIMS facilitates the formation of SiGe nanoparticles (2.1 +/- 0.8 nm) in the as-grown structure, and that presence of such nanoparticles acts as a seed for heterogeneous nucleation, which upon annealing results in the periodically arranged columnar self-assembly of SiGe core-shell nanocrystals. An increase in photocurrent intensity by more than an order of magnitude was achieved by annealing. Furthermore, a detailed discussion is provided on strain development within the structures, the consequential interface characteristics and its effect on the photocurrent spectra., M-ERA. NET project PhotoNanoP UEFISCDI Contract no. 33/2016, PCE project UEFISCDI Contract no. 122/2017 and by Romanian Ministry of Research and Innovation through NIMP Core Program PN19-03, contract no. 21 N/08.02.2019 and by the Technology Development Fund of the Icelandic Centre for Research, grant no. 159006-0611., "Peer Reviewed"

Publisher's version (útgefin grein), Background Electrical stimulation is widely used in experimental pain research but it lacks selectivity towards small nociceptive fibers. When using standard surface patch electrodes and rectangular pulses, large fibers are activated at a lower threshold than small fibers. Pin electrodes have been designed for overcoming this problem by providing a higher current density in the upper epidermis where the small nociceptive fibers mainly terminate. At perception threshold level, pin electrode stimuli are rather selectively activating small nerve fibers and are perceived as painful, but for high current intensity, which is usually needed to evoke sufficient pain levels, large fibers are likely co-activated. Long duration current has been shown to elevate the threshold of large fibers by the mechanism of accommodation. However, it remains unclear whether the mechanism of accommodation in large fibers can be utilized to activate small fibers even more selectively by combining pin electrode stimulation with a long duration pulse. Results In this study, perception thresholds were determined for a patch- and a pin electrode for different pulse shapes of long duration. The perception threshold ratio between the two different electrodes was calculated to estimate the ability of the pulse shapes to preferentially activate small fibers. The perception threshold ratios were compared between stimulation pulses of 5- and 50 ms durations and shapes of: exponential increase, linear increase, bounded exponential, and rectangular. Qualitative pain perception was evaluated for all pulse shapes delivered at 10 times perception threshold. The results showed a higher perception threshold ratio for long duration 50 ms pulses than for 5 ms pulses. The highest perception threshold ratio was found for the 50 ms, bounded exponential pulse shape. Results furthermore revealed different strength-duration relation between the bounded exponential- and rectangular pulse shapes. Pin electrode stimulation at high intensity was mainly described as "stabbing", "shooting", and "sharp". Conclusion These results indicate that long duration pulses with a bounded exponential increase preferentially activate the small nociceptive fibers with a pin electrode and concurrently cause elevated threshold of large non-nociceptive fibers with patch electrodes., Center for Neuroplasticity and Pain (CNAP) is supported by the Danish National Research Foundation (DNRF121)., "Peer Reviewed"

Pre-print (Óritrýnt handrit), Recently, Blockchain technology adoption has expanded to many application areas due to the evolution of smart contracts. However, developing smart contracts is non-trivial and challenging due to the lack of tools and expertise in this field. A promising solution to overcome this issue is to use Model-Driven Engineering (MDE), however, using models still involves a learning curve and might not be suitable for non-technical users. To tackle this challenge, chatbot or conversational interfaces can be used to assess the non-technical users to specify a smart contract in gradual and interactive manner. In this paper, we propose iContractBot, a chatbot for modeling and developing smart contracts. Moreover, we investigate how to integrate iContractBot with iContractML, a domainspecific modeling language for developing smart contracts, and instantiate intention models from the chatbot. The iContractBot framework provides a domain-specific language (DSL) based on the user intention and performs model-to-text transformation to generate the smart contract code. A smart contract use case is presented to demonstrate how iContractBot can be utilized for creating models and generating the deployment artifacts for smart contracts based on a simple conversation, We acknowledge the support of the Icelandic Centre for Research (Rannís) , [funding reference number 218202-051].

Publisher's version (útgefin grein), Antenna structures for modern applications are characterized by complex and unintuitive topologies that are difficult to develop when conventional, experience-driven techniques are of use.In this work, a method for the automatic generation of antenna geometries in a multi-objective set up has been proposed. The approach involves optimization of a generic spline-based radiator with an adjustable number of parameters using a nested, trust region-based algorithm. The latter iteratively increases the dimensionality of the radiator in order to gradually improve its performance. The method has been used to generate a set of nine antenna designs, representing a trade-off between minimization of reflection within 3.1 GHz to 10.6 GHz and a reduction of size. The properties of the optimized designs vary along the Pareto set from−10 dB to−20 dB and from 230 mm2to 757 mm2for the first and second objectives, respectively. The presented design approach has been validated against a genuine, population-based optimization routine. Furthermore, the smallest Pareto-optimal design has been compared to the antennas from the literature., This work was supported in part by the National Science Centre of Poland Grant 2017/27/B/ST7/00563 and by the National Centre for Research and Development Grant NOR/ POLNOR/HAPADS/0049/2019-00.

Publisher's version (útgefin grein), This study reports the direct production of an aluminium–manganese alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated for current efficiency measurements. The temperature was varied from 965–980 °C at a cathodic current density (CCD) of 0.9 A/cm2 and a cryolite ratio (CR) of 2.2. The manganese content was up to 3.0 wt%. Manganese was added in the form of Mn2O3. Bath samples were collected regularly and analyzed with ICP-MS to observe the decay of manganese during electrolysis. It was possible to produce Al-Mn alloys of up to 21 wt. % Mn. Current efficiency for the electrodeposition of Al–Mn alloy was estimated to be in the range of 93%. Current efficiencies with respect to aluminium were estimated. The solidified surfaces of the metal deposits were mostly flat, but some were deformed., Norges Teknisk-Naturvitenskapelige Universitet

Publisher's version (útgefin grein), In this paper, we study the staircase encoding of permutations, which maps a permutation to a staircase grid with cellsfilled with permutations. We consider many cases, where restricted to a permutation class, the staircase encoding be-comes a bijection to its image. We describe the image of thoserestrictions using independent sets of graphs weightedwith permutations. We derive the generating function for the independent sets and then for their weighted coun-terparts. The bijections we establish provide the enumeration of permutation classes. We use our results to uncoversome unbalanced Wilf-equivalences of permutation classesand outline how to do random sampling in the permutationclasses. In particular, we cover the classes Av (2314,3124), Av (2413,3142), Av(2413,3124), Av(2413,2134) and Av (2314,2143), as well as many subclasses.

Publisher's version (útgefin grein), The evaluation of the stakeholders’ perception of new hydropower projects is essential for assessing public acceptance, ensuring local involvement, and identifying feasible and desirable changes towards sustainable development. This study uses the concept of causal diagrams (CD) to identify the individual perspectives of stakeholders of two new hydropower projects, one in Switzerland (Val d’Ambra project) and one in Iceland (Hvammvirkjun project). For this purpose, semi-structured interviews with relevant stakeholders were conducted, which were then categorized into 5 interest groups. Using the software Atlas.ti, we identified and sequenced the perceived causality of impact pathways of the two projects. The results are exposed in two series of 10 topical causal networks, and two aggregated diagrams. For each case, CDs expose the complexity of multi-sequenced causalities between elements of a very heterogeneous nature, as expected and reported by stakeholders. This approach enables the identification of inter- and intra-group conflicting perspectives, and perceived uncertainties, concerning both subjectives matters along with much more tangible and predictable aspects. Our method enables the identification of areas where further research or better transfer of information between stakeholders is required. It also exposes how hydropower impacts can differ in time and space, when in one case study, intracommunity tensions and conflicts were identified at the earliest project stage, along with psychological distress of some local residents. Based on the presented CD, we conclude that this method can facilitate communication and problem-solving in complex social-environmental situations amid multiple stakeholder categories, which heterogeneity should not be underestimated., Peer Reviewed (ritrýnd grein)

Publisher's version (útgefin grein), This study reports the direct production of an aluminium-titanium alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated to current efficiency mea-surements. The temperature was varied from 960 to 980 ◦C at a cathodic current density (CCD) of 0.9 A/cm2 and a cryolite ratio (CR) of 2.2. The titanium content was up to 1.0 wt%. Titanium was added in the form of a TiO2 precursor. Bath samples were collected regularly and analyzed with ICP-MS to observe the decay of titanium during electrolysis. The current efficiency for electrodeposition of Al–Ti alloys was estimated to be at least around 90%. The surface of the solidified metal deposits was mostly flat, but some deposits were partially deformed., Norges Teknisk-Naturvitenskapelige Universitet

The ubiquitous reliance on software systems is increasing the need for ensuring their correctness. Runtime enforcement is a monitoring technique that uses moni- tors that can transform the actions of a system under scrutiny in order to alter its runtime behaviour and keep it in line with a correctness specification; these type of enforcement monitors are often called transducers. In runtime enforcement there is often no clear separation between the specification language describing the cor- rectness criteria that a system must satisfy, and the monitoring mechanism that actually ensures that these criteria are met. We thus aim to adopt a separation of concerns between the correctness specification describing what properties the sys- tem should satisfy, and the monitor describing how to enforce these properties. In this thesis we study the enforceability of the highly expressive branching time logic μHML, in a bid to identify a subset of this logic whose formulas can be adequately enforced by transducers at runtime. We conducted our study in relation to two different enforcement instrumentation settings, namely, a unidirectional setting that is simpler to understand and formalise but limited in the type of system actions it can transform at runtime, and a bidirectional one that, albeit being more complex, it allows transducers to effect and modify a wider set of system actions. During our investigation we define the behaviour of enforcement transducers and how they should be embedded with a system to achieve unidirectional and bidirectional enforcement. We also investigate what it means for a monitor to adequately enforce a logic formula, and define the necessary criteria that a monitor must satisfy in order to be adequate. Since enforcement monitors are highly intrusive, we also define a notion of optimality to use as a guide for identifying the least intrusive monitor that adequately enforces a formula. Using these enforcement definitions, we identify a μHML fragment that can be adequately enforced via enforcement transducers that drop the execution of certain actions. We then show that this fragment is maximally expressive, i.e., it is the largest subset that can be enforced via these type of enforcement monitors. We finally look into static alternatives to runtime enforcement and identify a static analysis technique that can also enforce the identified μHML fragment, but without requiring the system to execute.

Publisher's version (útgefin grein), Design of Butler matrices dedicated to Internet of Things and 5th generation (5G) mobile systems-where small size and high performance are of primary concern-is a challenging task that often exceeds capabilities of conventional techniques. Lack of appropriate, unified design approaches is a serious bottleneck for the development of Butler structures for contemporary applications. In this work, a low-cost bottom-up procedure for rigorous and unattended design of miniaturized 4 x 4 Butler matrices is proposed. The presented approach exploits numerical algorithms (governed by a set of suitable objective functions) to control synthesis, implementation, optimization, and fine-tuning of the structure and its individual building blocks. The framework is demonstrated using two miniaturized matrices with nonstandard output-port phase differences. Numerical results indicate that the computational cost of the design process using the presented framework is over 80% lower compared to the conventional approach. The footprints of optimized matrices are only 696 and 767 mm(2), respectively. Small size and operation frequency of around 2.6 GHz make the circuits of potential use for mobile devices dedicated to work within a sub-6 GHz 5G spectrum. Both structures have been benchmarked against the state-of-the-art designs from the literature in terms of performance and size. Measurements of the fabricated Butler matrix prototype are also provided., This work was supported in part by the National Science Centre of Poland Grant 2017/27/B/ST7/00563 and by the National Centre for Research and Development Grant NOR/POLNOR/HAPADS/0049/2019-00.

Publisher's version (útgefin grein), Malignant lymphomas are a heterogeneous group of malignancies that develop both in nodal and extranodal sites. The different tissues involved and the highly variable clinicopathological characteristics are linked to the association between the lymphoid neoplastic cells and the tissues they infiltrate. The immune system has developed mechanisms to protect the normal tissue from malignant growth. In this review, we aim to explain how T lymphocyte-driven control is linked to tumor development and describe the tumor-suppressive components of the resistant framework. This manuscript brings forward a new insight with regard to intercellular and intracellular signaling, the immune microenvironment, the impact of therapy, and its predictive implications. A better understanding of the key components of the lymphoma environment is important to properly assess the role of both B and T lymphocytes, as well as their interplay, just as two legendary boxers face each other in a heavyweight title final, as was the case of Ali versus Foreman., The research on the lymphoma microenvironment was funded by an internal grant of the Iuliu Hatieganu University, School of Doctoral Studies (PCD 2018-2021) (Minodora Desmirean), under the frame of European Social Found, Human Capital Operational Program 2014-2020, project no. POCU/380/6/13/125171 (Minodora Desmirean) and the Romanian Ministry of Research and Innovation, CCCDI-UEFISCDI, Project No. PN-III-P4-ID-PCCF-2016-0112 within PNCDI III, by an award for Young Research Teams 2020-2022 (Grant No. PN-III-P1-1.1-TE-2019-0271) (both Ciprian Tomuleasa) as well as by an international collaborative grant of the European Economic Space between Romania and Iceland 2020-2022 (Grant No. 19-COP-0031) (Ciprian Tomuleasa)., "Peer Reviewed"

Publisher's version (útgefin grein), This paper is motivated by the notion that coupling systems allows for mitigating the failure of individual ones. We present a novel approach to determining asymptotic stability and robustness of a network consisting of coupled dynamical systems, where individual system dynamics are represented through polynomial or rational functions. The analysis relies on a local analysis; thus, making it computationally implementable. We present an efficient computational method that relies on semidefinite programming. Importantly, for cases where multiple equilibrium points exist, we show how to determine regions around an asymptotically stable equilibrium point that bounds solutions. These regions increase when systems are coupled as we observe when applying the presented analysis framework to a mathematical model of a continuous stirred tank reactor. Importantly, the presented work has implications to other fields as well., "Peer Reviewed"

Post-print (lokagerð höfundar), We discuss the relationship between monads and their known generalisation, graded monads, which are especially useful for modelling computational effects equipped with a form of sequential composition. Specifically, we ask if a graded monad can be extended to a monad, and when such a degrading is in some sense canonical. Our particular examples are the graded monads of lists and non-empty lists indexed by their lengths, which gives us a pretext to study the space of all (non-graded) monad structures on the list and non-empty list endofunctors. We show that, in both cases, there exist infinitely many monad structures. However, while there are at least two ways to complete the graded monad structure on length-indexed lists to a monad structure on the list endofunctor, such a completion for non-empty lists is unique., This research was supported by the Icelandic Research Fund project grant no. 196323-052. T.U. was also supported by the Estonian Ministry of Education and Research institutional research grant no. IUT33-13., Peer reviewed (ritrýnd grein)