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For software applications with a significant level of user involvement, the traditional concept of usability has evolved into the more complex idea of user experience, which also covers emotional, cognitive or physical responses. In virtual reality, user experience also depends on the user perception related to some peculiarities of immersive environments, where also the devices employed for user interaction play a determinant role. This has led to the design of the Presence Questionnaire (PQ) for the evaluation of the effectiveness of virtual environments. This work analyzes the effects of two different interaction modalities on usability and sense of presence: in particular, the Myo armband, a gesture-based device for touchless interaction, is compared with the Vive handheld controller bundled with the HTC Vive headset. A total of 84 subjects were recruited to test the virtual environment and asked them to fill in a questionnaire obtained by combining the Usability Metric for User eXperience (UMUX) questionnaire, the System Usability Scale (SUS) and the presence questionnaire (PQ), which was specifically designed for virtual environments. A comparison between the scores obtained for the two interaction modalities revealed which questionnaire items are significantly influenced by the input interface and deduce some insights about the consequences on human factors.

Augmented Reality (AR) has become an increasingly used technology to support and enhance the enjoyment of cultural heritage. Particularly relevant is its importance for digital storytelling: by framing a portion of a fresco or painting with a smartphone, an AR mobile application can provide contextually relevant information, also in the form of multimedia content, that can help the user to understand the story and meaning behind the images. In this type of application, human factors are of fundamental importance for the effectiveness of the narrative: a mobile AR application must avoid distracting the user’s attention from the content in order to encourage a good level of concentration and immersion. The case study presented in this paper deals with a mobile AR application developed to guide visitors in the interpretation of the frescoes inside the Basilica of Saint Catherina of Alexandria in Galatina. The aim of the study is the analysis of the relations among usability, user experience and mental workload factors in AR-based digital storytelling.

We investigate the sensitivity of the Laser Interferometer Space Antenna (LISA) to the anisotropies of the Stochastic Gravitational Wave Background (SGWB). We first discuss the main astrophysical and cosmological sources of SGWB which are characterized by anisotropies in the GW energy density, and we build a Signal-to-Noise estimator to quantify the sensitivity of LISA to different multipoles. We then perform a Fisher matrix analysis of the prospects of detectability of anisotropic features with LISA for individual multipoles, focusing on a SGWB with a power-law frequency profile. We compute the noise angular spectrum taking into account the specific scan strategy of the LISA detector. We analyze the case of the kinematic dipole and quadrupole generated by Doppler boosting an isotropic SGWB. We find that $\beta\, \Omega_{\rm GW}\sim 2\times 10^{-11}$ is required to observe a dipolar signal with LISA. The detector response to the quadrupole has a factor $\sim 10^3 \,\beta$ relative to that of the dipole. The characterization of the anisotropies, both from a theoretical perspective and from a map-making point of view, allows us to extract information that can be used to understand the origin of the SGWB, and to discriminate among distinct superimposed SGWB sources., Comment: 48 page + appendices, 13 figures

The intent of this study is to promote and raise awareness of the Basilica of Saint Catherina of Alexandria in Galatina, a church endowed with such beauty as to be defined as astounding. In this article two technologies were used: Spatial Augmented Reality, better known as videomapping, to valorize the monument and narrate its story through images and sounds; and Augmented Reality, to facilitate the reading and interpretation of the most important frescoes located along all the internal walls of the Basilica. The goal is to create a unique path starting from the Basilica façade and continuing and winding through the interior spaces. One of the most extensive and best conserved cycles of Late Gothic frescoes in all of Europe unfolds on the nave of the church covering every corner, from the keystones down to the floor. An in-depth bibliographic research confirmed the presence of frescoes also on the exterior of the Basilica façade whose traces, however, are no longer visible today. Pietro Cavoti’ s illustrations give an idea of how the façade has changed over the years, before, during, and after the restorations that permanently removed the already faint traces of frescoes. The purpose of this research is to demonstrate how the combined use of these technologies can be considered a valid aid to support the enhancement, fruition, and understanding of a monument that is very important for the cultural heritage sector and a reference point for the local and religious community.

Combining constraints from microlensing and Lyman-$\alpha$ forest, we provide a simple argument to show that large spatial clustering of stellar-mass primordial black holes at the time of formation, such as the one induced by the presence of large non-Gaussianities, is ruled out. Therefore, it is not possible to evade existing constraints preventing stellar-mass primordial black holes to be a dominant constituent of the dark matter by boosting their initial clustering., Comment: 5 pages + supplementary material. 2 figures. v2: matching version published in PRL

K. G. Arun et al., The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about the fundamental theory of nature at play in the extreme gravity regime, where the gravitational interaction is both strong and dynamical. In this white paper, the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundamental physics where LISA observations of gravitational waves can be expected to provide key input. We provide the briefest of reviews to then delineate avenues for future research directions and to discuss connections between this working group, other working groups and the consortium work package teams. These connections must be developed for LISA to live up to its science potential in these areas., E. Berti is supported by NSF Grants No. PHY-1912550 and AST-2006538, NASA ATP Grants No. 17-ATP17-0225 and 19-ATP19-0051, NSF-XSEDE Grant No. PHY-090003, and NSF Grant PHY-20043. D. Blas is supported by a ‘Ayuda Beatriz Galindo Senior’ from the Spanish ‘Ministerio de Universidades’, grant BG20/00228. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya. The research leading of to these results has received funding from the Spanish Ministry of Science and Innovation (PID2020-115845GB-I00/AEI/10.13039/501100011033). K. Clough is supported by funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 693024). A. Cárdenas-Avendaño acknowledges funding from the Fundación Universitaria Konrad Lorenz (Project 5INV1) and from Will and Kacie Snellings. M. Crisostomi and E. Barausse are supported by the European Union’s H2020 ERC Consolidator Grant “GRavity from Astrophysical to Microscopic Scales” (Grant No. GRAMS-815673). P. Fleury received the support of a fellowship from “la Caixa” Foundation (ID 100010434). The fellowship code is LCF/BQ/PI19/11690018. C. Herdeiro thanks the support of the Center for Research and Development in Mathematics and Applications (CIDMA) through the Portuguese Foundation for Science and Technology (FCT - Fundação para a Ciência e a Tecnologia), references UIDB/04106/2020 and UIDP/04106/2020, the projects PTDC/FIS-OUT/28407/2017, CERN/FIS-PAR/0027/2019, PTDC/FIS-AST/3041/2020 and the European Union’s Horizon 2020 research and innovation (RISE) programme H2020-MSCA-RISE-2017 Grant No. FunFiCO-777740. P. Pani and E. Maggio acknowledge financial support provided under the European Union’s H2020 ERC, Starting Grant agreement no. DarkGRA–757480, and under the MIUR PRIN and FARE programmes (GW-NEXT, CUP: B84I20000100001), and support from the Amaldi Research Center funded by the MIUR program “Dipartimento di Eccellenza” (CUP: B81I18001170001). N.Frusciante was supported by Fundação para a Ciência e a Tecnologia (FCT) through the research grants UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-OUT/29048/2017, CERN/FIS-PAR/0037/2019, the FCT project “CosmoTests—Cosmological tests of gravity theories beyond General Relativity” with ref. number CEECIND/00017/2018 and the FCT project “BEYLA –BEYond LAmbda” with ref. number PTDC/FIS-AST/0054/2021. L.Lombriser was supported by a Swiss National Science Foundation Professorship grant (No. 170547). S.N. acknowledges support from the Alexander von Humboldt Foundation. D.N. acknowledges support from the NSF Grant No. PHY-2011784. R.B. acknowledges financial support from FCT – Fundação para a Ciência e a Tecnologia, I.P., under the Scientific Employment Stimulus - Individual Call - 2020.00470.CEECIND. V. Paschalidis acknowledges support from NSF Grant PHY-1912619 and NASA Grant 80NSSC20K1542 to the University of Arizona. B.S.S. is supported by NSF grants No. AST-2006384 and PHY-2012083. C.F.S. is supported by contracts ESP2017-90084-P and PID2019-106515GB-I00/AEI/10.13039/501100011033 (Spanish Ministry of Science and Innovation) and 2017-SGR-1469 (AGAUR, Generalitat de Catalunya). T. P. S. acknowledges partial support from the STFC Consolidated Grant No. ST/P000703/1. M. Ruiz acknowledges support from NASA Grant 80NSSC17K0070 to the University of Illinois at Urbana-Champaign. I.D. Saltas is supported by the Czech Science Foundation GAČR, Grant No. 21-16583M. N. Stergioulas is supported by the ESA Prodex grant PEA:4000132310 “LISA Stochastic Signals Analysis Pipeline”. F.V. acknowledges partial support from CNES. K.Y. acknowledges support from NSF Grant PHY-1806776, NASA Grant 80NSSC20K0523, a Sloan Foundation Research Fellowship and the Owens Family Foundation. K.Y. would like to also acknowledge support by the COST Action GWverse CA16104 and JSPS KAKENHI Grants No. JP17H06358. N. Yunes acknowledges support from NASA Grants No. NNX16AB98G, 80NSSC17M0041 and 80NSSC18K1352, NSF Award No. 1759615, and the Simons Foundation through MPS Award Number 896696. D.D. acknowledge financial support via an Emmy Noether Research Group funded by the German Research Foundation (DFG) under grant no. DO 1771/1-1.

The Standard Model Higgs potential becomes unstable at large Higgs field values where its quartic coupling becomes negative. While the tunneling lifetime of our current electroweak vacuum is comfortably longer than the age of the universe, quantum fluctuations during inflation might push the Higgs over the barrier, forming patches which might be lethal for our universe. We study the cosmological evolution of such regions and find that, at least in the thin wall approximation, they may be harmless as they collapse due to the backreaction of the Higgs itself. The presence of the Standard Model Higgs instability can provide a novel mechanism to end inflation and to reheat the universe through the evaporation of the black holes left over by the collapse of the Higgs bubbles. The bound on the Hubble rate during inflation may be therefore relaxed., 27 pages, 4 figures. v2: matching published version

With several dozen binary black hole events detected by LIGO/Virgo to date and many more expected in the next few years, gravitational-wave astronomy is shifting from individual-event analyses to population studies. Using the GWTC-2 catalog, we perform a hierarchical Bayesian analysis that for the first time combines several state-of-the-art astrophysical formation models with a population of primordial black holes (PBHs) and constrains the fraction of a putative subpopulation of PBHs in the data. We find that this fraction depends significantly on the set of assumed astrophysical models. While a primordial population is statistically favored against certain competitive astrophysical channels, such as globular clusters and nuclear stellar clusters, a dominant contribution from the stable-mass-transfer isolated formation channel drastically reduces the need for PBHs, except for explaining the rate of mass-gap events like GW190521. The tantalizing possibility that black holes formed after inflation are contributing to LIGO/Virgo observations could only be verified by further reducing uncertainties in astrophysical and primordial formation models, and it may ultimately be confirmed by third-generation interferometers., 13 pages, 7 figures. v3: matching published version

The work presents Agnano RiVive, an immersive Virtual Reality application developed to be used within the Museum of Preclassical Civilizations of the Southern Murgia in Ostuni, which preserves the findings of the Archaeological and Naturalistic Park of Santa Maria di Agnano. The application gives the user the possibility to explore the Upper Paleolithic settlement and interact with the old manufacts. The goal is to conduct the user to assist in the burial ritual of Ostuni 1, the world's oldest mother found in this site. A fundamental element is the paleoenvironment representation made possible by archaeobotanical studies. User experience was evaluated by submitting the Presence Questionnaire to 25 users. The results showed high levels of Involvement and Visual/Audio Fidelity and a strong correlation between them. Starting from this preliminary work, we propose to expand language and content to make the application educational and attractive to all types of Museum visitors.

This paper concerns the development of an immersive VR application for the enhancement of an inaccessible old Castle in Corsano, a small village in Salento - Italy. Starting from the 3D reconstruction of the building, the project allowed the development of an interaction system aimed at providing the user with the historical information about the Castle. These contents come from the analysis of the tangible cultural heritage (such as the architectural elements, the furniture, the decorative motifs of the castle, and their evolution through the centuries), but also from the collection of intangible heritage, such as reminiscences on folk customs and traditions related to the context of the castle. Moreover, in order to evaluate the user experience of the developed application, some tests were carried out on a heterogeneous sample of users, obtaining positive feedback on the degree of immersiveness and sense of presence of the application.

Making use of both the stochastic approach to the tunneling phenomenon and the threshold statistics, we offer a simple argument to show that critical bubbles may be correlated in first-order phase transitions and biased compared to the underlying scalar field spatial distribution. This happens though only if the typical energy scale of the phase transition is sufficiently high. We briefly discuss possible implications of this result, e.g. the formation of primordial black holes through bubble collisions., 6 pages, 1 figure. v2: matching published version

Primordial black holes possibly formed in the early universe could provide a significant fraction of the dark matter and would be unique probes of inflation. A smoking gun for their discovery would be the detection of a subsolar mass compact object. We argue that extreme mass-ratio inspirals will be ideal to search for subsolar-mass black holes not only with LISA but also with third-generation ground-based detectors such as Cosmic Explorer and the Einstein Telescope. These sources can provide unparalleled measurements of the mass of the secondary object at subpercent level for primordial black holes as light as ${\cal O}(0.01)M_\odot$ up to luminosity distances around hundred megaparsec and few gigaparsec for LISA and Einstein Telescope, respectively, in a complementary frequency range. This would allow claiming, with very high statistical confidence, the detection of a subsolar-mass black hole, which would also provide a novel (and currently undetectable) family of sources for third-generation detectors., Comment: 7 pages, 2 figures. v2: matching version to appear in PRL

The introduction of small Unmanned Aircraft Systems (sUAS) in an increasingly wide range of civil applications implies several challenges for the integration of manned and unmanned traffic in the controlled and uncontrolled low-level airspace, both at a technological and procedural level. This paper discusses the design of an integrated platform for the management of contingency events and the improvement of situation awareness of the pilot. To this end, a head-up display, based on augmented reality (AR) technology, is designed to provide the pilot with visual cues that should improve his awareness of admissible flight volumes. A force feedback is also provided by a haptic joystick, which suggests manoeuvres to avoid collisions or violation of airspace constraints. Tests in an actual airport facility are expected to be conducted in 2021. In the meantime, a possible realistic scenario is analysed, illustrating the interactions among the various actors and components of the system.

The next generation of gravitational-wave experiments, such as Einstein Telescope, Cosmic Explorer and LISA, will test the primordial black hole scenario. We provide a forecast for the minimum testable value of the abundance of primordial black holes as a function of their masses for both the unclustered and clustered spatial distributions at formation. In particular, we show that these instruments may test abundances, relative to the dark matter, as low as $10^{-10}$., Comment: 11 pages, 5 figures

The deformability of a compact object under the presence of a tidal perturbation is encoded in the tidal Love numbers (TLNs), which vanish for isolated black holes in vacuum. We show that the TLNs of black holes surrounded by matter fields do not vanish and can be used to probe the environment around binary black holes. In particular, we compute the TLNs for the case of a black hole surrounded by a scalar condensate under the presence of scalar and vector tidal perturbations, finding a strong power-law behavior of the TLN in terms of the mass of the scalar field. Using this result as a proxy for gravitational tidal perturbations, we show that future gravitational-wave detectors like the Einstein Telescope and LISA can impose stringent constraints on the mass of ultralight bosons that condensate around black holes due to accretion or superradiance. Interestingly, LISA could measure the tidal deformability of dressed black holes across the range from stellar-mass ($\approx 10^2 M_\odot$) to supermassive ($\approx 10^7 M_\odot$) objects, providing a measurement of the mass of ultralight bosons in the range $(10^{-17} - 10^{-13}) \, {\rm eV}$ with less than $10\%$ accuracy, thus filling the gap between other superradiance-driven constraints coming from terrestrial and space interferometers. Altogether, LISA and Einstein Telescope can probe tidal effects from dressed black holes in the combined mass range $(10^{-17} - 10^{-11}) \, {\rm eV}$., Comment: 17 pages, 5 figures. v2: matching published version

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality in the world, and leads to a substantial burden on healthcare services. Effective and timely management of patients with COPD has been essential to alleviate COPD exacerbation, improve the quality of life, and consequently reduce the economic burden. To achieve this, we propose an innovative tele-medicine system based on Smart Breath Analyzer (SBA) device and devoted to the tele-monitoring of exhaled air in patients suffering chronic respiratory failure and home-assisted by mechanical ventilation. In this work the main characteristics of the developed tele-medicine system are presented together with preliminary pre-clinical test results. The preliminary tests demonstrated the effective possibility to enter the SBAs in medical practice in home-ventilo-therapy protocols by suitable interpretation of the monitored parameters from a physiological point of view. Thanks to a network composed by many SBA devices that send patients data to a remote server, the doctor can tele-monitor the status of patient in order to check any state of exacerbation of the disease and consequently improve quality of life in COPD.

Primordial black holes could have been formed in the early universe from nonlinear cosmological perturbations reentering the cosmological horizon when the Universe was still radiation dominated. Starting from the shape of the power spectrum on superhorizon scales, we provide a simple prescription, based on the results of numerical simulations, to compute the threshold ${\ensuremath{\delta}}_{c}$ for primordial black hole formation. Our procedure takes into account both the nonlinearities between the Gaussian curvature perturbation and the density contrast and, for the first time in the literature, the nonlinear effects arising at horizon crossing, which increase the value of the threshold by about a factor two with respect to the one computed on superhorizon scales.

We calculate the exact formation probability of primordial black holes generated during the collapse at horizon re-entry of large fluctuations produced during inflation, such as those ascribed to a period of ultra-slow-roll. We show that it interpolates between a Gaussian at small values of the average density contrast and a Cauchy probability distribution at large values. The corresponding abundance of primordial black holes may be larger than the Gaussian one by several orders of magnitude. The mass function is also shifted towards larger masses., 4 pages, 3 figures, minor additions, references added, matches published version

Peer-to-peer streaming is a well-known technology for the large-scale distribution of real-time audio/video contents. Delay requirements are very strict in interactive real-time scenarios (such as synchronous distance learning), where playback lag should be of the order of seconds. Playback continuity is another key aspect in these cases: in presence of peer churning and network congestion, a peer-to-peer overlay should quickly rearrange connections among receiving nodes to avoid freezing phenomena that may compromise audio/video understanding. For this reason, we designed a QoS monitoring algorithm that quickly detects broken or congested links: each receiving node is able to independently decide whether it should switch to a secondary sending node, called “fallback node”. The architecture takes advantage of a multithreaded design based on lock-free data structures, which improve the performance by avoiding synchronization among threads. We will show the good responsiveness of the proposed approach on machines with different computational capabilities: measured times prove both departures of nodes and QoS degradations are promptly detected and clients can quickly restore a stream reception. According to PSNR and SSIM, two well-known full-reference video quality metrics, QoE remains acceptable on receiving nodes of our resilient overlay also in presence of swap procedures.

The latest events related to the spread of the Covid-19 virus have seen the rise of new social needs in countries like Italy, especially regarding the most vulnerable individuals. The emergency highlighted the insufficiency of some traditional methods of psychological support for that part of the population concretely facing the risk of social isolation. This research aims to discuss an innovative methodology that, by exploiting information and communication technologies (ICT) resources, combines the need to protect the vulnerable population with the need to prevent their social isolation, by intervening on the psychological well-being of users most at risk. In particular, we want to evaluate the feasibility of a Cross Reality (XR) project that combines the technologies of Virtual, Mixed and Augmented Reality with the most consolidated therapeutic methods of Mindfulness and Art Therapy.

Motor impairments affecting old people require a regular and reliable monitoring of the body functional autonomy. Low cost camera-based systems, initially designed for entertainment applications, have been evaluated for a possible adoption in diagnosis and rehabilitation. Unfortunately, their adoption is partially hampered by noise, precision and accuracy issues. In this paper we evaluate the performance of the Kinect One sensor in assessing the shoulder joint mobility in subjects with different body sizes: we measure the maximum angle reached by a patient raising his/her arms, the time needed to perform such action and the time the patient is able to keep his/her arms up. The preliminary tests conducted on two healthy subjects revealed no significant difference in terms of relative error among measures collected for subjects with different body heights and sizes. However, statistical tests suggested a correlation between the relative errors on large angle amplitudes and the time spent with arms up.

Among the techniques for digitalization and 3D modeling of real objects, photogrammetry is assuming an increasing importance due to easy procedures and low costs of hardware and software equipment. Thanks to the advances of the last years in computer vision, photogrammetry software can reconstruct the geometric 3D shape of an object from a series of pictures taken from different viewpoints. In particular, close-range photogrammetry for the reconstruction of small objects allows performing image acquisition around the target object almost automatically. In this paper we present a brief survey of the hardware setup, algorithms and software tools for photogrammetric acquisition and reconstruction applied to small objects, aimed at achieving a good photorealism level without an excessive computational load.

Tensor non-Gaussianities are a key ingredient to test the symmetries and the presence of higher spin fields during the inflationary epoch. Indeed, the shape of the three point correlator of the graviton is totally fixed by the symmetries of the de Sitter stage and, in the case of parity conservation, gets contributions only from the ordinary gravity action plus a higher derivative term called the (Weyl)$^3$ action. We discuss current and future bounds on the three point tensor contribution from the (Weyl)$^3$ term using cosmic microwave background (CMB) bispectra. Our results indicate that forthcoming experiments, such as LiteBIRD, CMB-S4 and CORE, will detect the presence of the (Weyl)$^3$ term if $M_p^4 L^4 \sim 10^{17} r^{-4}$, where $L$ parametrizes the strength of the (Weyl)$^3$ term and $r$ is the tensor-to-scalar ratio, which corresponds to $L\gtrsim 3.2 \times 10^5 M_p^{-1}$, while the current upper limit is $M_p^4 L^4 = (1.1 \pm 4.0) \times 10^{19} r^{-4}$ (68%CL)., 8 pages, 2 figures; version matching publication in PRD

Gesture-based touchless devices are becoming a widespread alternative to traditional gaming devices such as joysticks or gamepads. However, the impact of such devices on the user experience has to be evaluated, especially if we consider that most users are more familiar with classical handheld gaming controllers. In virtual reality applications, they influence not only the traditional usability, but also the user perception related to some peculiarities of immersive environments. In this paper, we evaluate both these aspects by comparing the user experience with the Myo armband touchless interface and the Vive controller distributed with the HTC Vive headset. We focused on a virtual navigator we developed for HTC Vive to allow users exploring the organs of the human body and navigating inside them. We recruited 78 subjects to test the virtual environment and asked them to fill in a questionnaire: we combined two generic purpose questionnaires focusing on the system usability (UMUX and SUS) and a presence questionnaire, which was specifically designed for virtual environments. We conducted a statistical analysis to study the effects of a touchless interaction on the user experience. The results revealed a better usability of the Vive controller, even though the effort to learn how to use the two devices is similar. In particular, difficulties in using Myo have a significant impact on immersion and adaptation in the virtual environment.

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that is expressed through different symptoms belonging to three different dimensions: inattention, impulsivity and motor hyperactivity, each of which contributes to the learning and adaptation problems within the different contexts of life. ADHD children have to focus on three main elements: learn to self-control, make and keep friends and feel good about themselves. The BRAVO (Beyond the tReatment of the Attention deficit hyperactiVity disOrder) project aims to realize an immersive therapeutic game context, based on an innovative ICT system, with which improving the relationship between young patients and therapies (administered by means of serious games and gamification). By using wearable equipment and Virtual and Augmented Reality devices, new personalized processes of therapy will be implemented. Such processes will be able to dynamically change in order to follow the patients evolution and support the therapists in the rehabilitation program management.

Natural user interfaces have been widely adopted in several application fields. In particular, they are employed in learning environments to increase the motivation and the engagement of students.

The experimentation of new effective visualization techniques provides viable technological solutions for the archaeological heritage fruition and the visitors involvement within cultural places (museums, gallery, archaeological sites).

Within the BRAVO project, we are designing four virtual characters that will interact with children affected by ADHD. In order to assess the quality of the designed characters, we propose a metric to subjectively evaluate the level of intelligibility of the character’s facial expression. The results of a preliminary user study conducted with 23 individuals show that our quality measure can be used to quickly identify flawed expressions and iteratively improve the design of the characters.

Minimally invasive techniques, such as laparoscopy and radiofrequency ablation of tumors, bring important advantages in surgery: by minimizing incisions on the patient's body, they can reduce the hospitalization period and the risk of postoperative complications. Unfortunately, they come with drawbacks for surgeons, who have a restricted vision of the operation area through an indirect access and 2D images provided by a camera inserted in the body. Augmented reality provides an "X-ray vision" of the patient anatomy thanks to the visualization of the internal organs of the patient. In this way, surgeons are free from the task of mentally associating the content from CT images to the operative scene. We present a navigation system that supports surgeons in preoperative and intraoperative phases and an augmented reality system that superimposes virtual organs on the patient's body together with depth and distance information. We implemented a combination of visual and audio cues allowing the surgeon to improve the intervention precision and avoid the risk of damaging anatomical structures. The test scenarios proved the good efficacy and accuracy of the system. Moreover, tests in the operating room suggested some modifications to the tracking system to make it more robust with respect to occlusions. Graphical Abstract Augmented visualization in minimally invasive surgery.

We explore the possibility that Dark Matter is the lightest hadron made of two stable color octet Dirac fermions ${\cal Q}$. The cosmological DM abundance is reproduced for $M_{\cal Q}\approx 12.5$ TeV, compatibly with direct searches (the Rayleigh cross section, suppressed by $1/M_{\cal Q}^6$, is close to present bounds), indirect searches (enhanced by ${\cal Q}{\cal Q}+\bar{\cal Q}\bar{\cal Q}\to {\cal Q}\bar{\cal Q}+{\cal Q}\bar{\cal Q}$ recombination), and with collider searches (where ${\cal Q}$ manifests as tracks, pair produced via QCD). Hybrid hadrons, made of $\cal Q$ and of SM quarks and gluons, have large QCD cross sections, and do not reach underground detectors. Their cosmological abundance is $10^5$ times smaller than DM, such that their unusual signals seem compatible with bounds. Those in the Earth and stars sank to their centers; the Earth crust and meteorites later accumulate a secondary abundance, although their present abundance depends on nuclear and geological properties that we cannot compute from first principles., Comment: 36 pages, 7 figures. v3: improved computation of the relic abundance; revised estimate of the indirect detection cross section

Nowadays grid portals are characterized by various and different features and are implemented in very differing programming languages and technologies, still having many structural aspects in common. This paper describes a RESTful Web API, named GRB_WAPI, specifically developed for grid computing that encapsulates all grid control and computation logic need to build a grid portal. Through the adoption of this API a portal developer does not have to deal with grid technical details focusing just on the high level design of her system and on some other aspects that concern presentation, such as portal usability and functionality. The idea of developing a traditional library has been discarded in order to free portal developers from a particular implementation technology. Thanks to this choice the portal presentation logic can be implemented in any web technology and can be deployed on a different server. Traditional Web Services and SOAP protocol approach has been discarded in order to adopt a RESTful approach to make the Web APIs lighter and also to take advantage of some other aspects illustrated in the paper.

The diffusion of small low cost sensors has opened new opportunities for the design of real-time monitoring systems in several application fields. Internet of Things (IoT) is a new branch of Information Technology that connects several of these heterogeneous devices through different network protocols to provide large scale interoperability. In this paper we describe how some open source software tools can be integrated to collect, monitor and process streams of data received in real-time by sensor devices. The tools we have employed are the Things-Board platform to collect sensor data and the Spark Streaming framework for cluster computing to perform data analytics. The presented architecture can be exploited in various monitoring scenarios (such as clinical, environmental or energetic processes) to study the trend of some key parameters and also to produce alerts in case of problematic situations. Without loss of generality, we focus on biomedical data about the breath of patients affected by chronic respiratory disease: real-time monitoring of breath parameters enables automatic ventilotherapy and allows also to warn doctors in time in severe cases.

Augmented reality plays an important role in cultural heritage and education. The magic effect of 3D animated objects can enhance students’ interest, attention and engagement in school subjects. Moreover, augmented reality can help understand spatial concepts and the working principles of complex mechanical components. In such context, machines designed by Leonardo Da Vinci are a perfect case study for augmented reality technologies. This paper presents a mobile augmented reality application developed for an exhibit on Leonardo’s inventions: it shows the overall structure and the working principles of some machines recognized on the pages of the Atlantic Codex. We used Blender to design the animated 3D models of the machines and the ARToolkit and Vuforia frameworks to superimpose virtual models over Leonardo’s sketches framed by the camera of mobile devices. Subjective data about user experience collected through some questionnaires proved how AR applications can improve the dominant learning style in accordance with Kolb’s theory.

We analyzed PSNR, BIPSNR, SSIM, 3SSIM, MSSSIM, VQM for various packet loss fractions.A lower bitrate mitigates PSNR impairments caused by packet losses.BIPSNR has less probability than PSNR to be significantly influenced by packet losses.Among structural similarity metrics, SSIM is the least affected by packet losses.VQM metric is the most affected by packet losses. Video quality is a key factor in modern video streaming systems. Video compression artifacts affect it but also delay, jitter and packet loss may compromise it. Objective metrics have been proposed to emulate the human visual system: several experimental works have evaluated their adherence to opinions expressed by real users. Instead of dealing with subjective tests, we focused on the effects of network packet losses on objective metrics: since quality metrics are generally computationally intensive, a convenient approach could consist in inferring information about transmission quality from network impairment statistics. We did experimental tests on two computer-animated videos, whose high color contrasts allow a fair comparison between content dependent and content independent metrics. We studied the encoding parameters that minimize/maximize the values of some metrics (PSNR, BI-PSNR, SSIM, 3SSIM, MSSSIM, VQM) for several packet loss percentages. We analyzed also the Empirical Cumulative Density Function of the degradations of quality metrics.

In this paper we describe a grid problem solving environment we developed for financial applications. We based its development on a portlet framework we have specifically developed and on a set of Web APIs that encapsulate all grid control and computation logic. Even though nowadays grid portals are characterized by various and different features and are implemented in very differing programming languages and technologies, we thought that they have many structural aspects in common. For this reason we decided to design and implement a set of Grid specific Web APIs, that we called GRB WAPI. Through them, a portal developer will not have to deal with grid technical details and will be able to manage a high level design. A portal developer will be able to concentrate on some other aspects that concern presentation, such as portal usability and functionality. We discarded the idea of developing a traditional library in order to free portal developers from a particular implementation technology. Thanks to this choice the portal presentation logic can be implemented in any web technology and can be on a different server

The paper deals with the development of virtual surgical simulator for microanastomosis developed within the INTERREG (Italy-Greece) MICRO project. Microanastomosis is a surgical technique that involves, under optical magnification, the conjunction of blood vessels of a few millimeters diameter and is used also to support the surgical treatment of tumours. This manuscript describes the two principal solutions analysed during the progress of the MICRO project. The first step concerns the development of the simulator using the Unity3D engine; the second step describes an evolution of the surgical simulator to support remote control by a haptic interface via web using the WebGL platform based on JavaScript code. For both, a force feedback module has been implemented that reads data coming from the simulator and converts them to generate a servo control action on the haptic interface. For both solutions, some results of the implemented simulator are described .

Aim of this work was to study the perception of affordances in VR according to a cognitive neuroscience. In order to investigate this topic we focused our analysis on the perception of affordances during a game, the Leap Motion Controller (LM). The sample was composed of 10 university students matched by age and sex. The subjects performed in Thinking training and in Immersive Affordance Condition (a virtual training with LM and a Real training). After each training the subject had to perform a recognition task. During the task ERP components were measured through EEG. The results highlighted that, during the LM training, attentional components changed. In the occipital lobes, which is entrusted to visual sensory, we got increased latencies; on the contrary, in frontal lobe, where the brain mainly activates for attention and action planning, we got decreased latencies.

P2P streaming systems exploit the high scalability of P2P networks to propagate multimedia streams to wide areas in a distributed fashion. A P2P network is made up of several logic connections among peer nodes, which can form a mesh or a tree overlay. Interactive real-time streaming imposes very strict delay constraints: in e-learning environments, for instance, only a high level of synchrony with the live event may allow users to ask questions in real-time to the lecture speaker. Despite their resilience to peer churning, mesh overlays are affected by a high and variable delay, which hampers their adoption in interactive applications. Playback discontinuity, caused by missing chunks, may be a serious problem too, since it may compromise the speech understanding. On the contrary, multi-tree MDC-based overlays can guarantee a smooth playback continuity, since a stream can be fluently reproduced also when some descriptions are lost. The queuing and the elaboration delay of the nodes should be kept under control to reduce the overall end-to-end delay on each tree branch. In this work we describe a framework for the construction of reliable tree overlays: we designed a smooth switch-to-fallback mechanism to quickly replace nodes leaving the overlay, a channel for packet recovery and a very efficient engine that collects MDC descriptions coming from parent nodes. The experimental data we reported in the last section reveal a low CPU usage and a very low elaboration delay in collecting MDC descriptions.