565 research outputs found
Monoclonal antibodies against human astrocytomas and their reactivity pattern
The establishment of hybridomas after fusion of X63-Ag8.653 mouse myeloma cells and splenocytes from mice hyperimmunized against human astrocytomas is presented. The animals were primed with 5 × 106 chemically modified uncultured or cultured glioma cells. Six weeks after the last immunization step an intrasplenal booster injection was administrated and 3 days later the spleen cells were prepared for fusion experiments. According to the specificity analysis of the generated antibodies 7 hybridoma products (MUC 7-22, MUC 8-22, MUC 10-22, MUC 11-22, MUC 14-22, MUC 15-22 and MUC 2-63) react with gliomas, neuroblastomas and melanomas as well as with embryonic and fetal cells but do not recognize non-neurogenic tumors. The selected monoclonal antibodies (McAbs) of IgG1 and IgG2a isotypes are not extensively characterized but these antibodies have been demonstrated to be reactive with a panel of glioma cell lines with varying patterns of antigen distribution. Using the McAbs described above and a series of cryosections of glioma biopsies and paraffin sections of the same material as well as glioma cultures established from these, variable antigenic profiles among glioma cell populations could be demonstrated. From these results it is evident that there is not only a distinct degree of antigenic heterogeneity among and within brain tumors, but also that the pattern of antigenic expression can change continuously. Some of the glioma associated antigens recognized by the selected antibodies persist after fixation with methanol/acetone and Karnovsky's fixative and probably are oncoembryonic/oncofetal antigen(s). The data suggest that the use of McAbs recognizing tumor associated oncofetal antigens in immunohistochemistry facilitates objective typing of intracranial malignancies and precise analysis of fine needle brain/tumor biopsies in a sensitive and reproducible manner
Applications of Information Nonanticipative Rate Distortion Function
The objective of this paper is to further investigate various applications of
information Nonanticipative Rate Distortion Function (NRDF) by discussing two
working examples, the Binary Symmetric Markov Source with parameter
(BSMS()) with Hamming distance distortion, and the multidimensional
partially observed Gaussian-Markov source. For the BSMS(), we give the
solution to the NRDF, and we use it to compute the Rate Loss (RL) of causal
codes with respect to noncausal codes. For the multidimensional Gaussian-Markov
source, we give the solution to the NRDF, we show its operational meaning via
joint source-channel matching over a vector of parallel Gaussian channels, and
we compute the RL of causal and zero-delay codes with respect to noncausal
codes.Comment: 5 pages, 3 figures, accepted for publication in IEEE International
Symposium on Information Theory (ISIT) proceedings, 201
Sequential Necessary and Sufficient Conditions for Capacity Achieving Distributions of Channels with Memory and Feedback
We derive sequential necessary and sufficient conditions for any channel
input conditional distribution to maximize the
finite-time horizon directed information defined by for channel distributions
and
, where
and are the
channel input and output random processes, and is a finite nonnegative
integer.
\noi We apply the necessary and sufficient conditions to application examples
of time-varying channels with memory and we derive recursive closed form
expressions of the optimal distributions, which maximize the finite-time
horizon directed information. Further, we derive the feedback capacity from the
asymptotic properties of the optimal distributions by investigating the limit
without any \'a priori
assumptions, such as, stationarity, ergodicity or irreducibility of the channel
distribution. The necessary and sufficient conditions can be easily extended to
a variety of channels with memory, beyond the ones considered in this paper.Comment: 57 pages, 9 figures, part of the paper was accepted for publication
in the proceedings of the IEEE International Symposium on Information Theory
(ISIT), Barcelona, Spain 10-15 July, 2016 (Date of submission of the
conference paper: 25/1/2016
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
Causal Rate Distortion Function on Abstract Alphabets: Optimal Reconstruction and Properties
A causal rate distortion function with a general fidelity criterion is
formulated on abstract alphabets and a coding theorem is derived. Existence of
the minimizing kernel is shown using the topology of weak convergence of
probability measures. The optimal reconstruction kernel is derived, which is
causal, and certain properties of the causal rate distortion function are
presented.Comment: 5 pages, Submitted to Internation Symposium on Information
Theory(ISIT) 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
Electron Scattering and Hybrid Phonons in Low Dimensional Laser Structures made with GaAs/AlxGa1-xAs
We theoretically and numerically present the hybrid phonon modes for the
double heterostructure GaAs/AlxGa1-xAs and their interactions with electrons.
More specifically, we have calculated the electron capture within a symmetric
quantum well via the emission of hybrid phonons. Our investigation shows that
the capture rates via the hybrid phonons are matched to the rates predicted by
the dielectric continuum (DC) model and the concentration of aluminium which is
an important parameter for controlling the electron capture process in light
emitting diodes (LED).Comment: 11 page
Investigation of the Caregivers’ Quality of Life in Patients with Renal Failure
The care of patients with chronic renal failure is a specialized field in the field of health with significant peculiarities. The initial aim of the study is the investigation of the caregivers’ quality of life in patients with renal failure, which arises both from the stress
of the progression of the disease itself and from the burdens of care. The main variables of the research, the burden/fatigue of the caregivers and the general health index, are concepts that can be quantified, thanks to the special psychometric tools that have been developed for their measurement. The study was conducted from January 2022 until May 2022. The final sample of the present study is 100 caregivers of patients with renal failure. The need for permanent and continuous care requires on the part of the caregiver’s daily engagement, the dedication of hours, neglect of personal needs or social activities and generally permanent changes in his life and daily life. Caregivers are at high risk of deteriorating quality of life due to their time and energy in providing care. The result of the correlation analysis confirms the research hypotheses that the health status of the caregivers is negatively affected by the burden and fatigue they receive from their work
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