582 research outputs found
Information Nonanticipative Rate Distortion Function and Its Applications
This paper investigates applications of nonanticipative Rate Distortion
Function (RDF) in a) zero-delay Joint Source-Channel Coding (JSCC) design based
on average and excess distortion probability, b) in bounding the Optimal
Performance Theoretically Attainable (OPTA) by noncausal and causal codes, and
computing the Rate Loss (RL) of zero-delay and causal codes with respect to
noncausal codes. These applications are described using two running examples,
the Binary Symmetric Markov Source with parameter p, (BSMS(p)) and the
multidimensional partially observed Gaussian-Markov source. For the
multidimensional Gaussian-Markov source with square error distortion, the
solution of the nonanticipative RDF is derived, its operational meaning using
JSCC design via a noisy coding theorem is shown by providing the optimal
encoding-decoding scheme over a vector Gaussian channel, and the RL of causal
and zero-delay codes with respect to noncausal codes is computed.
For the BSMS(p) with Hamming distortion, the solution of the nonanticipative
RDF is derived, the RL of causal codes with respect to noncausal codes is
computed, and an uncoded noisy coding theorem based on excess distortion
probability is shown. The information nonanticipative RDF is shown to be
equivalent to the nonanticipatory epsilon-entropy, which corresponds to the
classical RDF with an additional causality or nonanticipative condition imposed
on the optimal reproduction conditional distribution.Comment: 34 pages, 12 figures, part of this paper was accepted for publication
in IEEE International Symposium on Information Theory (ISIT), 2014 and in
book Coordination Control of Distributed Systems of series Lecture Notes in
Control and Information Sciences, 201
Surface scattering velocities in III-nitride quantum well laser structures via the emission of hybrid phonons
We have theoretically and numerically studied nitride-based quantum well (QW)
laser structures. More specifically, we have used a QW made with III-nitride
where the width of the barrier region is large relative to the electron mean
free path, and we have calculated the electron surface capture velocities by
considering an electron flux which is captured into the well region. The
process is assisted by the emission of the longitudinal optical phonons as
predicted by the hybrid (HB) model. The results of surface capture velocities
via the emission of HB phonons are compared to the emission of the dielectric
continuum phonons (Zakhleniuk et al 1999 Phys. Status Solidi a 176 79). Our
investigation shows that the two different phonon models predict almost the
same results for the non-retarded limit. Furthermore, the surface capture
velocities strongly depend on the size of the structure and the heterostructure
materials. Lastly, a comparison to the recent experimental values shows that
our model could accurately describe the experimentally measured parameters of
the quantum capture processes
Suppression of electron relaxation and dephasing rates in quantum dots caused by external magnetic fields
An external magnetic field has been applied in laterally coupled dots (QDs)
and we have studied the QD properties related to charge decoherence. The
significance of the applied magnetic field to the suppression of
electron-phonon relaxation and dephasing rates has been explored. The coupled
QDs have been studied by varing the magnetic field and the interdot distance as
other system parameters. Our numerical results show that the electron
scattering rates are strongly dependent on the applied external magnetic field
and the details of the double QD configuration.Comment: 13 pages, 6 figure
High-Pressure Synthesis of a Pentazolate Salt
The pentazolates, the last all-nitrogen members of the azole series, have
been notoriously elusive for the last hundred years despite enormous efforts to
make these compounds in either gas or condensed phases. Here we report a
successful synthesis of a solid state compound consisting of isolated
pentazolate anions N5-, which is achieved by compressing and laser heating
cesium azide (CsN3) mixed with N2 cryogenic liquid in a diamond anvil cell. The
experiment was guided by theory, which predicted the transformation of the
mixture at high pressures to a new compound, cesium pentazolate salt (CsN5).
Electron transfer from Cs atoms to N5 rings enables both aromaticity in the
pentazolates as well as ionic bonding in the CsN5 crystal. This work provides a
critical insight into the role of extreme conditions in exploring unusual
bonding routes that ultimately lead to the formation of novel high nitrogen
content species
Whitman and Nietzsche: A Comparative Study of Their Thought
This volume will be a great aid to students and scholars alike in American literature, American thought, the history of ideas, and comparative literature. Stavrou draws from the entire bodies of work by Whitman and Nietzsche to explore the parallels in the authors' conceptions of paradox, the totality of life, and solitude among other themes in this exploration of the underlying philosophical similarities of these two great writers of the nineteenth century
Further expansion of the alien seaweed Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman & Procacini (Ulvophyceae, Bryopsidales) in the Eastern Mediterranean Sea
We are grateful to Andreas Antoniou (Dep. of Environment, Ministry of Agriculture, Rural Development & Environment, Cyprus) for his assistance in the preparation of the illustrations. We would also like to thank Dr. Sotiris Orfanidis (NAGREF – Fisheries Research Institute, Kavala, Greece) for his valuable advice and both the DFMR and HSR / HCMR Rhodes crew and George Hatiris for their help in samplings. Special thanks are due to Dinos Leonidou (SeaQuest Divers Cyprus) for accompanying the deep dive for sampling Caulerpa at Cavo Greco. We are grateful to the Total Foundation (Paris) for its funding support to this study within the framework of the project “Brown algal ecology and biodiversity in the eastern Mediterranean Sea” and to the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland, funded by the Scottish Funding Council and contributing institutions; grant reference HR09011).Peer reviewedPublisher PD
Positioning as Service for 5G IoT Networks
Big Data and Artificial Intelligence are new tech- nologies to improve indoor localization. It focuses on the use of machine learning probabilistic algorithms to extract, model and analyse live and historical signal data obtained from several sources. In this respect, the data generated by 5G network and the Internet of Things is quintessential for precise indoor positioning in complex building environments. In this paper, we present a new architecture for assets and personnel location management in 5G network with an emphasis on vertical sectors in smart cities. Moreover, we explain how Big Data and Machine learning can be used to offer positioning as service. Additionally, we implement a new deep learning model for 3D positioning using the proposed architecture. The performance of the proposed model is compared against other Machine Learning algorithms
An atypical case of scleroderma
Systemic sclerosis, or scleroderma is a rare systemic autoimmune rheumatic disease with an annual incidence of 3.7 per million in the UK. We report the case of a 55 year old female presenting with insidious onset weight loss, pruritus and worsening shortness of breath. Examination revealed signs of cardiac failure, fine inspiratory crepitations, hepatomegaly and diffuse cutaneous depigmentation although with minimal peripheral sclerodactyly. The anti-nuclear antibodies were interestingly negative and malignancy was not found on thorough screening. The patient was commenced on treatment with oral prednisone and intravenous cyclophosphamide for diffuse cutaneous systemic sclerosis. A rapid response in cardiac function, respiratory symptoms and fatigue was noted. In addition, skin texture rapidly improved with associated re-pigmentation seen within two weeks of commencing treatment. However, within two months of discharge the patient died. The cause of death was thought to be due to cardiac arrhythmia likely secondary to chronic myocarditis
Investigation of powder flowability at low stresses by DEM modelling
Ball indentation is a technique capable of assessing powder flowability down to very low consolidation stresses (≤1 kPa). With this method, powder flowability is determined by measuring the hardness of a powder bed, which allows the unconfined yield strength to be inferred via the constraint factor. The latter is well established for continuum materials, whereas for particulate systems its dependency on stress level and powder properties is not well defined. This work investigates these factors by simulating the ball indentation method using DEM. The constraint factor is shown to be independent of pre-consolidation stress. Constraint factor generally increases with interface energy for relatively cohesionless powders, though not for cohesive powders. An increase in plastic yield stress leads to a decrease in the constraint factor. Increasing the coefficient of interparticle static friction reduces the constraint factor, while increasing the coefficient of inter-particle rolling friction significantly increases the constraint factor
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