112 research outputs found
A Cloud Platform-as-a-Service for Multimedia Conferencing Service Provisioning
Multimedia conferencing is the real-time exchange of multimedia content
between multiple parties. It is the basis of a wide range of applications
(e.g., multimedia multiplayer game). Cloud-based provisioning of the
conferencing services on which these applications rely will bring benefits,
such as easy service provisioning and elastic scalability. However, it remains
a big challenge. This paper proposes a PaaS for conferencing service
provisioning. The proposed PaaS is based on a business model from the state of
the art. It relies on conferencing IaaSs that, instead of VMs, offer
conferencing substrates (e.g., dial-in signaling, video mixer and audio mixer).
The PaaS enables composition of new conferences from substrates on the fly.
This has been prototyped in this paper and, in order to evaluate it, a
conferencing IaaS is also implemented. Performance measurements are also made.Comment: 6 pages, 6 figures, IEEE ISCC 201
A Cloud-Based Architecture for Multimedia Conferencing Service Provisioning
Multimedia conferencing is the real-time exchange of multimedia content between multiple parties. It is the basis of several interactive multiuser applications, such as distance learning and multimedia multiplayer online games. The cloud-based provisioning of the conferencing services on which these applications rely on can have several benefits, including the easy provisioning of new applications, efficient use of resources, and elastic scalability. This paper proposes a holistic cloud-based architecture for conferencing service provisioning, which covers both the infrastructure and platform layers of the cloud. The proposed infrastructure layer offers conferencing substrates-as-a-service (e.g., dial-in signaling, video mixing, and audio mixing), instead of virtual machines or containers. The platform layer abstracts the details of the conferencing concepts and offers a high-level interface to simplify conference service provisioning for a wide range of service and application providers (experts versus non-experts). It also enables the on-the-fly scaling of the running conferences while guaranteeing the required quality of service, enables substrates composition to create new conferencing services, and eases the reuse of conferencing services in building new applications. The presented architecture is supported by a proof-of-concept prototype and performance measurements. The latter provides the analysis of resource allocation efficiency and response time, as well as the scalability of the system under suboptimal and over-provisioned conditions. It also provides recommendations for service providers regarding the best alternatives for provisioning their service
IoT end-user applications provisioning in the cloud: State of the art
© 2016 IEEE. Internet of Things (IoT) is expected to enable a myriad of end-user applications by interconnecting physical objects. Cloud computing is a promising paradigm for provisioning IoT end-user applications in a cost-efficient manner. IoT end-user applications are provisioned in cloud settings using PaaS and offered as SaaS. This paper focuses on the PaaS aspects of IoT end-user applications provisioning. It critically reviews the state of the art. The critical review discusses the PaaS on the whole spectrum of IoT verticals and also the PaaS dealing with specific IoT verticals
The effect of personality traits on consumers' preferences for extra virgin olive oil
The aim of this paper is to investigate the role of psychological factors on building the consumer's behavioral decision process towards extra virgin olive oil, with special attention paid to the organic attribute. The paper hypothesises that differences in consumers' personality traits, such as food-related personality traits, purchasing habits and lifestyles, affect consumers' preferences for extra virgin olive oil. The methodological framework is based on the specification of an extended hybrid choice model (HCM), which was estimated following a two-step procedure. In the first step, a structural equation model was estimated to test for hierarchical relationships between latent variables to explain purchasing intentions towards an organic olive oil. In the second step, the predicted latent variables were introduced in a random parameter logit (RPL) model to investigate the main determinants of consumers' choices related to extra virgin olive oil and the specific role of the organic attribute. The results from this study reinforce the need to include the psychological characteristics of consumers, such as attitudes, food-related personality traits, purchase habits and lifestyle orientation, to better explain how individuals make food choices and to better understand the decision maker's process. Interestingly, Catalan consumers perceive a disutility from the organic attribute compared to other production system alternatives (conventional and PDO), while subjective norms and a higher perception of behavioral control only partially mitigate this effect. Environmental or health concerns seem to not be relevant to consumers' choices related to olive oil as the conventional olive oil is already perceived as a healthy product per se. (C) 2016 Elsevier Ltd. All rights reserved.Postprint (published version
Vortex gap solitons in spin-orbit-coupled Bose-Einstein condensates with competing nonlinearities
The formation and dynamics of full vortex gap solitons (FVGSs) is
investigated in two-component Bose-Einstein condensates with spin-orbit
coupling (SOC), Zeeman splitting (ZS), and competing cubic and quintic
nonlinear terms, while the usual kinetic energy is neglected, assuming that it
is much smaller than the SOC and ZS terms. Unlike previous SOC system with the
cubic-only attractive nonlinearity, in which solely semi-vortices may be
stable, with the vorticity carried by a single component, the present system
supports stable FVGS states, with the vorticity present in both components
(such states are called here full vortex solitons, to stress the difference
from the half-vortices). They populate the bandgap in the system's linear
spectrum. In the case of the cubic self-attraction and quintic repulsion,
stable FVGSs with a positive effective mass exist near the top of the bandgap.
On the contrary, the system with cubic self-repulsion and quintic attraction
produces stable FVGSs with a negative mass near the bottom of the bandgap.
Mobility and collisions of FVGSs with different topological charges are
investigated too.Comment: 14 pages,9 figures, 77 references. Communication in Nonlinear Science
and Numerical Simulation, in pres
Vortex solitons in quasi-phase-matched photonic crystals
We report solutions for stable compound solitons supported by a
three-dimensional (3D) quasi-phase-matched (QPM) photonic crystal in a medium
with the quadratic () nonlinearity. The photonic crystals are
introduced with a checkerboard structure, which can be realized by means of the
available technology. The solitons are built as four-peak vortex modes of two
types, rhombuses and squares. Their stability areas are identified in the
system's parametric space, while all bright vortex solitons are subject to
strong azimuthal instability in uniform media. Possibilities for
experimental realization of the solitons are outlined too.Comment: 6 pages, 6 figures, 39 reference
Statics and dynamics of domain patterns in hexagonal-orthorhombic ferroelastics
We study the statics and the dynamics of domain patterns in proper
hexagonal-orthorhombic ferroelastics; these patterns are of particular interest
because they provide a rare physical realization of disclinations in crystals.
Both our static and dynamical theories are based entirely on classical,
nonlinear elasticity theory; we use the minimal theory consistent with
stability, symmetry and ability to explain qualitatively the observed patterns.
After scaling, the only parameters of the static theory are a temperature
variable and a stiffness variable. For moderate to large stiffness, our static
results show nested stars, unnested stars, fans and other nodes, triangular and
trapezoidal regions of trapped hexagonal phase, etc observed in electron
microscopy of Ta4N and Mg-Cd alloys, and also in lead orthovanadate (which is
trigonal-monoclinic); we even find imperfections in some nodes, like those
observed. For small stiffness, we find patterns like those observed in the
mineral Mg-cordierite. Our dynamical studies of growth and relaxation show the
formation of these static patterns, and also transitory structures such as
12-armed bursts, streamers and striations which are also seen experimentally.
The major aspects of the growth-relaxation process are quite unlike those in
systems with conventional order parameters, for it is inherently nonlocal; for
example, the changes from one snapshot to the next are not predictable by
inspection.Comment: 9 pages, 3 figures (1 b&w, 2 colour); animations may be viewed at
http://huron.physics.utoronto.ca/~curnoe/sim.htm
A comprehensive survey on Fog Computing: State-of-the-art and research challenges
Cloud computing with its three key facets (i.e.,
Infrastructure-as-a-Service, Platform-as-a-Service, and Softwareas-
a-Service) and its inherent advantages (e.g., elasticity and
scalability) still faces several challenges. The distance between
the cloud and the end devices might be an issue for latencysensitive
applications such as disaster management and content
delivery applications. Service level agreements (SLAs) may also
impose processing at locations where the cloud provider does not
have data centers. Fog computing is a novel paradigm to address
such issues. It enables provisioning resources and services outside
the cloud, at the edge of the network, closer to end devices, or
eventually, at locations stipulated by SLAs. Fog computing is not
a substitute for cloud computing but a powerful complement. It
enables processing at the edge while still offering the possibility
to interact with the cloud. This paper presents a comprehensive
survey on fog computing. It critically reviews the state of
the art in the light of a concise set of evaluation criteria. We
cover both the architectures and the algorithms that make fog
systems. Challenges and research directions are also introduced.
In addition, the lessons learned are reviewed and the prospects
are discussed in terms of the key role fog is likely to play in
emerging technologies such as tactile Internet
Optical Investigation of Broadband White-Light Emission in Self-Assembled Organic–Inorganic Perovskite (C 6
Prevalence and etiology of community-acquired pneumonia in immunocompromised patients
Background. The correct management of immunocompromised patients with pneumonia is debated. We evaluated the prevalence, risk factors, and characteristics of immunocompromised patients coming from the community with pneumonia. Methods. We conducted a secondary analysis of an international, multicenter study enrolling adult patients coming from the community with pneumonia and hospitalized in 222 hospitals in 54 countries worldwide. Risk factors for immunocompromise included AIDS, aplastic anemia, asplenia, hematological cancer, chemotherapy, neutropenia, biological drug use, lung transplantation, chronic steroid use, and solid tumor. Results. At least 1 risk factor for immunocompromise was recorded in 18% of the 3702 patients enrolled. The prevalences of risk factors significantly differed across continents and countries, with chronic steroid use (45%), hematological cancer (25%), and chemotherapy (22%) the most common. Among immunocompromised patients, community-acquired pneumonia (CAP) pathogens were the most frequently identified, and prevalences did not differ from those in immunocompetent patients. Risk factors for immunocompromise were independently associated with neither Pseudomonas aeruginosa nor non\u2013community-acquired bacteria. Specific risk factors were independently associated with fungal infections (odds ratio for AIDS and hematological cancer, 15.10 and 4.65, respectively; both P = .001), mycobacterial infections (AIDS; P = .006), and viral infections other than influenza (hematological cancer, 5.49; P < .001). Conclusions. Our findings could be considered by clinicians in prescribing empiric antibiotic therapy for CAP in immunocompromised patients. Patients with AIDS and hematological cancer admitted with CAP may have higher prevalences of fungi, mycobacteria, and noninfluenza viruses
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