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We report $\ensuremath{\beta}$-detected NMR of ion-implanted $^{8}\mathrm{Li}$ in a single crystal and thin film of the strongly correlated metal ${\mathrm{LaNiO}}_{3}$. Spin-lattice relaxation measurements reveal two distinct local environments, both metallic as evident from $T$-linear Korringa $1/{T}_{1}$ below $200\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ with slopes comparable to other metals. A small approximately temperature-independent Knight shift of $\ensuremath{\sim}74\phantom{\rule{0.16em}{0ex}}\mathrm{ppm}$ is observed, yielding a normalized Korringa product characteristic of substantial antiferromagnetic correlations. We find no evidence for a magnetic transition from 4 to $310\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. The similarity of these features in the two very different samples indicates that they are intrinsic and unrelated to dilute oxygen vacancies. We attribute the two environments to two distinct but similar crystallographic $^{8}\mathrm{Li}$ sites and not to any form of phase inhomogeneity, but this is inconsistent with the conventional rhombohedral structure of ${\mathrm{LaNiO}}_{3}$, and also cannot be simply explained by the common alternative orthorhombic or monoclinic distortions.

We have studied a mosaic of 1T-CrSe

We report measurements of the diffusion rate of isolated ion-implanted $^{8}{\mathrm{Li}}^{+}$ within $\ensuremath{\sim}120\text{ }\text{ }\mathrm{nm}$ of the surface of oriented single-crystal rutile ${\mathrm{TiO}}_{2}$ using a radiotracer technique. The $\ensuremath{\alpha}$ particles from the $^{8}\mathrm{Li}$ decay provide a sensitive monitor of the distance from the surface and how the depth profile of $^{8}\mathrm{Li}$ evolves with time. The main findings are that the implanted ${\mathrm{Li}}^{+}$ diffuses and traps at the (001) surface. The $T$ dependence of the diffusivity is described by a bi-Arrhenius expression with activation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures it has a much smaller barrier of 0.0313(15) eV. We consider possible origins for the surface trapping, as well the nature of the low-$T$ barrier.

We have studied a mosaic of 1T-CrSe$_2$ single crystals using $\beta$-detected nuclear magnetic resonance of $^{8}$Li from 4 to 300 K. We identify two broad resonances that show no evidence of quadrupolar splitting, indicating two magnetically distinct environments for the implanted ion. We observe stretched exponential spin lattice relaxation and a corresponding rate ($1/T_1$) that increases monotonically above 200 K, consistent with the onset of ionic diffusion. A pronounced maximum in $1/T_1$ is observed at the low temperature magnetic transition near 20 K. Between these limits, $1/T_1$ instead exhibits a broad minimum with a remarkable absence of strong features in the vicinity of structural and magnetic transitions between 150 and 200 K. Together, the results suggest $^{8}$Li$^{+}$ site occupation within the van der Waals gap between CrSe$_2$ trilayers. Possible origins of the two environments are discussed.

We demonstrate the application of implanted-ion $\beta$-detected NMR as a probe of ionic liquid molecular dynamics through the measurement of $^8$Li spin-lattice relaxation (SLR) and resonance in 1-ethyl-3-methylimidazolium acetate. The motional narrowing of the resonance, and the local maxima in the SLR rate, $1/T_1$, imply a sensitivity to sub-nanosecond Li$^+$ solvation dynamics. From an analysis of $1/T_1$, we extract an activation energy ${E_A = 74.8 \pm 1.5}$ meV and Vogel-Fulcher-Tammann constant ${T_{\mathrm{VFT}} = 165.8 \pm 0.9}$ K, in agreement with the dynamic viscosity of the bulk solvent. Near the melting point, the lineshape is broad and intense, and the form of the relaxation is non-exponential, reflective of our sensitivity to heterogeneous dynamics near the glass transition. The depth resolution of this technique may later provide a unique means of studying nanoscale phenomena in ionic liquids.

We report measurements on the high-temperature ionic and low-temperature electronic properties of the three-dimensional topological insulator ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{2}\mathrm{Se}$ using ion-implanted $^{8}\mathrm{Li}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-detected nuclear magnetic relaxation and resonance. With implantation energies in the range $5--28\phantom{\rule{0.28em}{0ex}}\mathrm{keV}$, the probes penetrate beyond the expected range of the topological surface state, but are still within $250\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$ of the surface. At temperatures above $\ensuremath{\sim}150\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, spin-lattice relaxation measurements reveal isolated $^{8}\mathrm{Li}^{+}$ diffusion with an activation energy ${E}_{A}=0.185(8)\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ and attempt frequency ${\ensuremath{\tau}}_{0}^{\ensuremath{-}1}=8\ifmmode\pm\else\textpm\fi{}3\ifmmode\times\else\texttimes\fi{}{10}^{11}{\mathrm{s}}^{\ensuremath{-}1}$ for atomic site-to-site hopping. At lower temperature, we find a linear Korringa-type relaxation mechanism with a field-dependent slope and intercept, which is accompanied by an anomalous field dependence to the resonance shift. We suggest that these may be related to a strong contribution from orbital currents or the magnetic freeze-out of charge carriers in this heavily compensated semiconductor, but that conventional theories are unable to account for the extent of the field dependence. Conventional NMR of the stable host nuclei may help elucidate their origin.

We report measurements of the diffusion rate of isolated ion-implanted ^{8}Li^{+} within ∼120 nm of the surface of oriented single-crystal rutile TiO_{2} using a radiotracer technique. The α particles from the ^{8}Li decay provide a sensitive monitor of the distance from the surface and how the depth profile of ^{8}Li evolves with time. The main findings are that the implanted Li^{+} diffuses and traps at the (001) surface. The T dependence of the diffusivity is described by a bi-Arrhenius expression with activation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures it has a much smaller barrier of 0.0313(15) eV. We consider possible origins for the surface trapping, as well the nature of the low-T barrier.

Background: The growing interest in neuroimaging technologies generates a massive amount of biomedical data of high dimensionality. Tensor-based analysis of brain imaging data has been recognized as an effective analysis that exploits its inherent multi-way nature. In particular, the advantages of tensorial over matrix-based methods have previously been demonstrated in the context of functional magnetic resonance imaging (fMRI) source localization. However, such methods can also become ineffective in realistic challenging scenarios, involving, e.g., strong noise and/or significant overlap among the activated regions. Moreover, they commonly rely on the assumption of an underlying multilinear model generating the data. New method: This paper aims at investigating the possible gains from exploiting the 4-dimensional nature of the brain images, through a higher-order tensorization of the fMRI signal, and the use of less restrictive generative models. In this context, the higher-order block term decomposition (BTD) and the PARAFAC2 tensor models are considered for the first time in fMRI blind source separation. A novel PARAFAC2-like extension of BTD (BTD2) is also proposed, aiming at combining the effectiveness of BTD in handling strong instances of noise and the potential of PARAFAC2 to cope with datasets that do not follow the strict multilinear assumption. Comparison with existing methods: The methods were tested using both synthetic and real data and compared with state of the art methods. Conclusions: The simulation results demonstrate the effectiveness of BTD and BTD2 for challenging scenarios (presence of noise, spatial overlap among activation regions and inter-subject variability in the haemodynamic response function (HRF)). © 2018 Elsevier B.V.

This study explored how to increase the on-site energy production of row-houses in a new urban development area located in Trondheim (Norway) from the early design stages. The process consisted in an evolutionary algorithmic for optimizing the shape of the building's roof in order to maximize the use of solar energy. Starting from the roof's profile of the traditional Norwegian house unit, different configurations have been tested. The process allowed changing iteratively the inclination and the size of the roof's surfaces. The selected roofs’ shapes guaranteed to get the maximum solar radiation and the solar mapping analysis allows individualizing the most suitable areas to install solar systems on the roofs’ surfaces of the entire district. The final configuration of the row-houses permitted to increase the solar potential around 30% respect the initial design solution. © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

Advances in computer and communications technology have deeply affected the way we communicate. Social media have emerged as a major means of human communication. However, a major limitation in such media is the lack of non-verbal stimuli, which sometimes hinders the understanding of the message, and in particular the associated emotional content. In an effort to compensate for this, people started to use emoticons, which are combinations of keyboard characters that resemble facial expressions, and more recently their evolution: emojis, namely, small colorful images that resemble faces, actions and daily life objects. This paper presents evidence of the effect of emojis on memory retrieval through a functional Magnetic Resonance Imaging (fMRI) study. A total number of fifteen healthy volunteers were recruited for the experiment, during which successive stimuli were presented, containing words with intense emotional content combined with emojis, either with congruent or incongruent emotional content. Volunteers were asked to recall a memory related to the stimulus. The study of the reaction times showed that emotional incongruity among word+emoji combinations led to longer reaction times in memory retrieval compared to congruent combinations. General Linear Model (GLM) and Blind Source Separation (BSS) methods have been tested in assessing the influence of the emojis on the process of memory retrieval. The analysis of the fMRI data showed that emotional incongruity among word+emoji combinations activated the Broca's area (BA44 and BA45) in both hemispheres, the Supplementary Motor Area (SMA) and the inferior prefrontal cortex (BA47), compared to congruent combinations. Furthermore, compared to pseudowords, word+emoji combinations activated the left Broca's area (BA44 and BA45), the amygdala, the right temporal pole (BA48) and several frontal regions including the SMA and the inferior prefrontal cortex. ispartof: PLoS One vol:15 issue:7 pages:e0234104- ispartof: location:United States status: Published online

NMR spectra of Mg2+ ions in ionic liquids were recorded using a highly sensitive variant of NMR spectroscopy known as β-NMR. The β-NMR spectra of MgCl2 in EMIM-Ac and EMIM-DCA compare favourably with conventional NMR, and exhibit linewidths of ∼3 ppm, allowing for discrimination of species with oxygen and nitrogen coordination.

BACKGROUND: The growing interest in neuroimaging technologies generates a massive amount of biomedical data of high dimensionality. Tensor-based analysis of brain imaging data has been recognized as an effective analysis that exploits its inherent multi-way nature. In particular, the advantages of tensorial over matrix-based methods have previously been demonstrated in the context of functional magnetic resonance imaging (fMRI) source localization. However, such methods can also become ineffective in realistic challenging scenarios, involving, e.g., strong noise and/or significant overlap among the activated regions. Moreover, they commonly rely on the assumption of an underlying multilinear model generating the data. NEW METHOD: This paper aims at investigating the possible gains from exploiting the 4-dimensional nature of the brain images, through a higher-order tensorization of the fMRI signal, and the use of less restrictive generative models. In this context, the higher-order block term decomposition (BTD) and the PARAFAC2 tensor models are considered for the first time in fMRI blind source separation. A novel PARAFAC2-like extension of BTD (BTD2) is also proposed, aiming at combining the effectiveness of BTD in handling strong instances of noise and the potential of PARAFAC2 to cope with datasets that do not follow the strict multilinear assumption. COMPARISON WITH EXISTING METHODS: The methods were tested using both synthetic and real data and compared with state of the art methods. CONCLUSIONS: The simulation results demonstrate the effectiveness of BTD and BTD2 for challenging scenarios (presence of noise, spatial overlap among activation regions and inter-subject variability in the haemodynamic response function (HRF)). ispartof: JOURNAL OF NEUROSCIENCE METHODS vol:315 pages:17-47 ispartof: location:Netherlands status: published

Tensor-based analysis of brain imaging data, in particular functional Magnetic Resonance Imaging (fMRI), has proved to be quite effective in exploiting their inherently multidimensional nature. It commonly relies on a trilinear model generating the analyzed data. This assumption, however, may prove to be quite strict in practice; for example, due to the natural intra-subject and inter-subject variability of the Haemodynamic Response Function (HRF). This paper investigates the possible gains from the adoption of a less strict trilinear model, such as PARAFAC2, which allows a more flexible representation of the fMRI data in the temporal domain. In this context, and inspired by a recently reported successful application of the Block Term Decomposition (BTD) model to a 4-way tensorization of the fMRI signal, a PARAFAC2-like extension of BTD (called here BTD2) is proposed. Simulation results are presented, that reveal the pros and cons of these tensorial methods, demonstrating BTD2's enhanced robustness to noise.

NMR spectra of Mg2+ ions in ionic liquids were recorded using a highly sensitive variant of NMR spectroscopy known as β-NMR. The β-NMR spectra of MgCl2 in EMIM-Ac and EMIM-DCA compare favourably with conventional NMR, and exhibit linewidths of ∼3 ppm, allowing for discrimination of species with oxygen and nitrogen coordination.

Περιέχει το πλήρες κείμενο Η παρούσα εργασία στοχεύει να αναδείξει τους τρόπους με τους οποίους θα μπορούσαν οι υποψήφιοι παλαιογράφοι να αυξήσουν τα επίπεδα της πληροφοριακής τους παιδείας είτε μέσα από το Πρόγραμμα Σπουδών των πανεπιστημιακών σπουδών τους είτε και μέσα από δράσεις άλλων φορέων, με έμφαση στις δράσεις των Δημοσίων Βιβλιοθηκών και της Εθνικής Βιβλιοθήκης μιας χώρας. Στο πλαίσιο της παρούσας εισήγησης, ο πληροφοριακός γραμματισμός εκλαμβάνεται ως η υιοθέτηση της κατάλληλης πληροφοριακής συμπεριφοράς, ώστε να αποκτήσει κανείς το πληροφοριακό υλικό που καλύπτει τις ανάγκες του αξιοποιώντας οποιοδήποτε πνευματικό ή υλικό μέσο, έχοντας βεβαίως πάντα κατά νου την κριτική αποτίμηση αυτού του υλικού και τη μεγάλη σημασία που έχει η ορθή και σοφή χρήση του μέσα σε μία Κοινωνία της Πληροφορίας, όπως η σημερινή. Λαμβάνοντας υπ’ όψιν τα πολύ χαμηλά επίπεδα πληροφοριακής παιδείας που έχουν καταγραφεί έως τώρα στη βιβλιογραφία για τους υποψήφιους επιστήμονες και επαγγελματίες Ανθρωπιστικών Επιστημών, η έρευνα αυτή έρχεται να καταγράψει τις πληροφοριακές ανάγκες ενός πολύ ιδιαίτερου κλάδου, με τον οποίο ελάχιστα έχει ασχοληθεί η Επιστήμη της Πληροφόρησης, αλλά και να αναδείξει τρόπους με τους οποίους θα μπορούσαν οι υποψήφιοι παλαιογράφοι να αυξήσουν το πληροφοριακό τους επίπεδο αλλά και να το εκμεταλλευτούν δεόντως, προκειμένου να ανταποκρίνονται ικανοποιητικά στις επαγγελματικές και ερευνητικές τους ανάγκες. Υπό αυτήν την έννοια, λοιπόν, η παρούσα εισήγηση θα μπορούσε να αποτελέσει ένα εφαλτήριο της Επιστήμης της Πληροφόρησης για ενασχόλησή της με έναν επιστημονικό κλάδο, ο οποίος πέραν των συνηθών πληροφοριακών μέσων, όπως για παράδειγμα βιβλία και περιοδικά, πολύ συχνά αντλεί τις επιζητούμενες πληροφορίες του μέσα από στοιχεία, όπως μεταξύ άλλων τα υδατόσημα, τα βιβλιογραφικά σημειώματα ή ακόμα και τον διάκοσμο ενός χειρογράφου, στοιχεία που αποτελούν βασικές πληροφοριακές πηγές, προκειμένου να είναι σε θέση ένας παλαιογράφος να ασχοληθεί επισταμένως με την επιστημονική περιγραφή ενός χειρογράφου και του περιεχομένου του.

Filter bank-based multicarrier (FBMC) systems have been considered as a prevalent candidate for replacing the long established cyclic prefix (CP)-based orthogonal frequency division multiplexing (CP-OFDM) in the physical layer of next generation communications systems. In particular, offset quadrature amplitude modulation (OQAM)-based FBMC has received increasing attention due to, among other features, its potential for maximum spectral efficiency. It suffers, however, from an intrinsic self-interference effect, which complicates signal processing tasks at the receiver, including synchronization, channel estimation and equalization. In a multiple-input multiple-output (MIMO) configuration, the multi-antenna interference has also to be taken into account. (Semi-)blind FBMC/OQAM receivers have been little studied so far and mainly for single-antenna systems. The problem of joint channel estimation and data detection in a MIMO-FBMC/OQAM system, given limited or no training information, is studied in this paper through a tensor-based viewpoint in the light of the success of such techniques in OFDM applications. Simulation-based comparisons with CP-OFDM are included, for realistic transmission models.

We report a comparison of the $1/T_1$ spin lattice relaxation rates (SLR) for $^9Li$ and $^8Li$ in Pt and SrTiO$_{3}$, in order to differentiate between magnetic and electric quadrupolar relaxation mechanisms. In Pt, the ratio of the $1/T_{1}$ spin relaxation rates $R_{Pt}$ was found to be 6.82(29), which is close to but less than the theoretical limit of $\sim7.68$ for pure magnetic relaxation. In SrTiO$_{3}$ this ratio was found to be 2.7(3), which is close but larger than the theoretical limit of $\sim2.14$ expected for pure electric quadrupolar relaxation. These results bring new insight into the nature of the fluctuations in the local environment of implanted $^8Li$ observed by $\beta$-NMR.

The span of most chemical shifts recorded in conventional 25Mg-NMR spectroscopy is ~ 100 ppm. Accordingly, linewidths of ~ 10 ppm or better are desirable to achieve adequate resolution for applications in chemistry. Here we present first high-field 31Mg- β-NMR measurements of 31Mg+ ions implanted into a MgO single crystal carried out at the ISAC facility at TRIUMF. The resonances recorded at 2.5 T and 3.5 T show strong linewidth dependency on the applied RF power, ranging from ~ 419 ppm for the highest RF power down to ~ 48 ppm for the lowest one.

The growing use of neuroimaging technologies generates a massive amount of biomedical data that exhibit high dimensionality. Tensor-based analysis of brain imaging data has been proved quite effective in exploiting their multiway nature. The advantages of tensorial methods over matrix-based approaches have also been demonstrated in the context of functional magnetic resonance imaging (fMRI) data analysis. However, such methods can become ineffective in demanding scenarios, involving, e.g., strong noise and/or significant overlapping of activated regions. This paper aims at investigating the possible gains that can be obtained from a better exploitation of the spatial dimension, through a higher (than 3)-order tensor modeling of the fMRI signals. In this context, a higher-order Block Term Decomposition (BTD) is applied, for the first time in fMRI analysis. Its effectiveness in handling strong instances of noise is demonstrated via extensive simulation results. © Springer International Publishing AG 2017.