Measuring user Quality of Experience in social VR systems

Virtual Reality (VR) is a computer-generated experience that can simulate physical presence in real or imagined environments [7]. A social VR system is an application that allows multiple users to join a collaborative Virtual Environment (VE), such as a computer-generated 3D scene or a 360-degree natural scene captured by an omnidirectional camera, and communicate with each other, usually by means of visual and audio cues. Each user is represented in the VE as a computer-generated avatar [3] or, in recently proposed systems, with a virtual representation based on live captures [1]. Depending on the system, the user’ virtual representation can also interact with the virtual environment, for example by manipulating virtual objects, controlling the appearance of the VE, or controlling the playout of additional media in the VE. The interest for social Virtual Reality (VR) systems dates back to the late 90s [4, 8] but has recently increased [2, 5, 6] due to the availability of affordable head-mounted displays on the consumer market and to the appearance of new applications, such as Facebook Spaces, YouTube VR, Hulu VR, which explicitly aim at including social features in existing VR platforms for multimedia delivery. In this talk, we will address the problem of measuring user Quality of Experience (QoE) in social VR systems. We will review the studies that have analysed how different features of a social VR system design, such as avatar appearance and behavioural realism, can affect user’s experience, and propose a comparison of the objective and subjective measures used in the literature to quantify user QoE in social VR. Finally, we will discuss the use case of watching movies together in VR and present the results of one of our recent studies focusing on this scenario, designed and performed in the framework of the European project VRTogether (http://vrtogether.eu). Particularly, we show an analysis of correlation between the objective and subjective measurements collected during our study, to provide guidelines toward the design of a unified methodology to monitor and quantify users’ QoE in social VR systems. The open questions to be addressed in the future in order to achieve such goal are also discussed

Fast glycorrhachia and cerebrospinal fluid protein as predictors of sensory block in anesthesia with subarachnoid Ropivacaine

BACKGROUND: Identify if glycorrhachia and cerebrospinal fluid protein could influence the time of sensory block to T10, the duration and the metameric block's level, after a standard dose of Ropivacaine. METHODS: 80 patients, ASA I - III undergoing to transurethral prostate resection with spinal anesthesia in a prospected open study were recruited. A 0.2 ml liquor's sample was taken; glycorrhachia, by glycemic stix and CSF protein, by urinary stix, were got, before Ropivacaine 0.5% 15 mg injection (0.10 - 0.15 mlsec). After anti-trendelemburg, with 30 ° tilting for 15 min, the onset of sensory block to T10, the maximum metameric level to 15' and the time of sensory block were reported. The data collection were analyzed using the software language R. RESULTS: A significant correlation liquor specific weigh preoperative glycemia (0.749), liquoral specific weigh glycorrhachia (rho = 0.751; R2 = 0.564; P 0.05) and specific weigh CSF protein (rho = 0.684; R2 = 0.468; P 0.05) were reported. Inverse relation CSF weightsensory block level (rho -0.789, P 0.05, R2 0.621) was evidenced. Inverse relation onset time to T10 glycorrhachia (84%) and cephalic block glycorrhachia (76%) were found. Inverse correlation onset time to T 10 CSF protein and cephalic block proteinorrachia was respectively 84% and 67%. A rho of 0.712 with R2 of 51% BMI onset to T10 and rho of 0.681 with R2 of 51% BMI maximum cephalic block with P 0.05 were reported. CONCLUSIONS: The predictability of a iso-hypobaric local anesthetic could reduce the risk of procedure failure and adverse events by further cephalic spread

From perfect to fractal transmission in spin chains

Perfect state transfer is possible in modulated spin chains, imperfections however are likely to corrupt the state transfer. We study the robustness of this quantum communication protocol in the presence of disorder both in the exchange couplings between the spins and in the local magnetic field. The degradation of the fidelity can be suitably expressed, as a function of the level of imperfection and the length of the chain, in a scaling form. In addition the time signal of fidelity becomes fractal. We further characterize the state transfer by analyzing the spectral properties of the Hamiltonian of the spin chain.Comment: 8 pages, 10 figures, published versio

MODIFICAZIONI URBANE. ARCHITETTURE E CONNESSIONI A PALERMO

Il volume raccoglie gli esiti della ricerca e della didattica dei laboratori di Progettazione architettonica svolti presso il Dipartimento di Architettura dell\u2019Universit\ue0 degli Studi di Palermo, sul tema del progetto urbano. L\u2019obiettivo \ue8 quello di dimostrare come l\u2019esperienza di progetto sia capace di riaffermare la qualit\ue0 architettonica urbana nella citt\ue0 contemporanea. Inoltre, viene presentato un percorso di ricognizione e di conoscenza attraverso l\u2019elaborazione di progetti didattici, dal quale emerge una forte attenzione alle trasformazioni della citt\ue0.The book collects the results of the research and teaching of the architectural design laboratories carried out at the Department of Architecture of the University of Palermo, on the theme of the urban project. The goal is to demonstrate how the project experience is able to reaffirm the urban architectural quality in the contemporary city. In addition, a path of recognition and knowledge is presented through the development of educational projects, from which emerges a strong emphasis on the transformations of the city

Use of partial load operating conditions for latent thermal energy storage management

A proper management of thermal energy storage (TES) charging and discharging processes allows the final users to optimize the performance of TES systems. In this paper, an experimental research is carried out to study how the percentage of charge in a latent heat TES system (partial load operating conditions) influences the discharge process. Several charging and discharging processes were performed at a constant heat transfer fluid (HTF) mass flow rate of 0.5 kg/s and temperature of 155 °C and 105 °C, respectively. High density polyethylene (HDPE) with a total mass of 99.5 kg was used as phase change material (PCM) in a 0.154m3 storage tank based on the shelland-tube heat exchanger concept. Five different percentages of charge have been studied: 58 %, 73 %, 83 %, 92 %, and 97 % (baseline test). Results showed that by modifying the percentage of charge, the time required for the charging process was reduced between 97.2% and 68.8% in comparison to the baseline case. However, the energy accumulated was only reduced a maximum of 35.1% and a minimum of 5.2%, while the heat transfer rates during the first 60 min of discharge were reduced a maximum of 45.8% and a minimum of 6%. Therefore, partially charging the TES system not lower than 85% of its maximum energy capacity becomes a good option if the final application accepts a maximum decrease of discharging heat transfer rates of 10% if compared to the fully charged system.The work was partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER), ENE2015-64117-C5-3-R (MINECO/FEDER), and ULLE10-4E-1305). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2014 SGR 123). GREA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This project has received funding from the European Commission Seventh Framework Programme (FP/2007-2013) under Grant agreement No. PIRSES-GA-2013-610692 (INNOSTORAGE) and from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 657466 (INPATH-TES). Jaume Gasia would like to thank the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya for his research fellowship (2017 FI_B1 00092). Alvaro de Gracia would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2014-19940. Simone Arena would like to thank the Department of Mechanical, Chemical and Materials Engineering of the University of Cagliari for funding his research grant

Extended neutral hydrogen filamentary network in NGC 2403

We present new neutral hydrogen (H 

Leptogenesis in models with keV sterile neutrino dark matter

We analyze leptogenesis in gauge extensions of the Standard Model with keV sterile neutrino dark matter. We find that both the observed dark matter abundance and the correct baryon asymmetry of the Universe can simultaneously emerge in these models. Both the dark matter abundance and the leptogenesis are controlled by the out of equilibrium decays of the same heavy right handed neutrino.Comment: 6 pages, 1 figur