29,934 research outputs found
Features of pulsed synchronization of a systems with a tree-dimensional phase space
Features of synchronization picture in the system with the limit cycle
embedded in a three-dimensional phase space are considered. By the example of
Ressler system and Dmitriev - Kislov generator under the action of a periodic
sequence of delta - function it is shown, that synchronization picture
significantly depends on the direction of pulse action. Features of
synchronization tons appeared in these models are observed.Comment: 16 pages, 11 figure
Spin interference and Fano effect in electron transport through a mesoscopic ring side-coupled with a quantum dot
We investigate the electron transport through a mesoscopic ring side-coupled
with a quantum dot(QD) in the presence of Rashba spin-orbit(SO) interaction. It
is shown that both the Fano resonance and the spin interference effects play
important roles in the electron transport properties. As the QD level is around
the Fermi energy, the total conductance shows typical Fano resonance line
shape. By applying an electrical gate voltage to the QD, the total transmission
through the system can be strongly modulated. By threading the mesoscopic ring
with a magnetic flux, the time-reversal symmetry of the system is broken, and a
spin polarized current can be obtained even though the incident current is
unpolarized.Comment: 5 pages, 5 figure
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Interleukin 2 activation of natural killer cells rapidly induces the expression and phosphorylation of the Leu-23 activation antigen.
IL-2 potentiates both growth and cytotoxic function of T lymphocytes and NK cells. Resting peripheral blood NK cells can respond directly to rIL-2, without requirement for accessory cells or cofactors, and enhanced cytotoxicity can be measured within a few hours after exposure to this lymphokine. In this study, we describe an activation antigen, Leu-23, that is rapidly induced and phosphorylated after IL-2 stimulation of NK cells and a subset of low buoyant density T lymphocytes. Previously, it has been uncertain whether all NK cells or only a subset are responsive to IL-2. Since within 18 h after exposure to IL-2, essentially all NK cells express Leu-23, these findings indicate that all peripheral blood NK cells are responsive to stimulation by IL-2. The Leu-23 antigen is a disulfide-bonded homodimer, composed of 24-kD protein subunits with two N-linked oligosaccharides. Appearance of this glycoprotein on NK cells is IL-2 dependent and closely parallels IL-2-induced cytotoxicity against NK-resistant solid tumor cell targets
Evaluating the semantic web: a task-based approach
The increased availability of online knowledge has led to the design of several algorithms that solve a variety of tasks by harvesting the Semantic Web, i.e. by dynamically selecting and exploring a multitude of online ontologies. Our hypothesis is that the performance of such novel algorithms implicity provides an insight into the quality of the used ontologies and thus opens the way to a task-based evaluation of the Semantic Web. We have investigated this hypothesis by studying the lessons learnt about online ontologies when used to solve three tasks: ontology matching, folksonomy enrichment, and word sense disambiguation. Our analysis leads to a suit of conclusions about the status of the Semantic Web, which highlight a number of strengths and weaknesses of the semantic information available online and complement the findings of other analysis of the Semantic Web landscape
An efficient and principled method for detecting communities in networks
A fundamental problem in the analysis of network data is the detection of
network communities, groups of densely interconnected nodes, which may be
overlapping or disjoint. Here we describe a method for finding overlapping
communities based on a principled statistical approach using generative network
models. We show how the method can be implemented using a fast, closed-form
expectation-maximization algorithm that allows us to analyze networks of
millions of nodes in reasonable running times. We test the method both on
real-world networks and on synthetic benchmarks and find that it gives results
competitive with previous methods. We also show that the same approach can be
used to extract nonoverlapping community divisions via a relaxation method, and
demonstrate that the algorithm is competitively fast and accurate for the
nonoverlapping problem.Comment: 14 pages, 5 figures, 1 tabl
Fractal-like Distributions over the Rational Numbers in High-throughput Biological and Clinical Data
Recent developments in extracting and processing biological and clinical data are allowing quantitative approaches to studying living systems. High-throughput sequencing, expression profiles, proteomics, and electronic health records are some examples of such technologies. Extracting meaningful information from those technologies requires careful analysis of the large volumes of data they produce. In this note, we present a set of distributions that commonly appear in the analysis of such data. These distributions present some interesting features: they are discontinuous in the rational numbers, but continuous in the irrational numbers, and possess a certain self-similar (fractal-like) structure. The first set of examples which we present here are drawn from a high-throughput sequencing experiment. Here, the self-similar distributions appear as part of the evaluation of the error rate of the sequencing technology and the identification of tumorogenic genomic alterations. The other examples are obtained from risk factor evaluation and analysis of relative disease prevalence and co-mordbidity as these appear in electronic clinical data. The distributions are also relevant to identification of subclonal populations in tumors and the study of the evolution of infectious diseases, and more precisely the study of quasi-species and intrahost diversity of viral populations
Epidemiology of Any and Vaccine-Type Anogenital Human Papillomavirus Among 13-26-Year-Old Young Men After HPV Vaccine Introduction
PURPOSE:
The aims of this study were to determine prevalence of and factors associated with any human papillomavirus (HPV) and vaccine-type HPV among young men after vaccine introduction, stratified by vaccination status.
METHODS:
Young men were recruited from clinical sites from 2013 to 2015, completed a survey, and were tested for 36 anogenital HPV types. We determined factors associated with ≥1 HPV type among all participants, and vaccine-type HPV (HPV6, 11, 16, and/or 18) among all, vaccinated and unvaccinated participants, using multivariable regression.
RESULTS:
Mean age was 21.5 years and 26% had received at least one HPV vaccine dose. HPV prevalence was lower in vaccinated versus unvaccinated young men (50.5% vs. 62.6%, p = .03). HPV positivity was discordant by anogenital site. At both sites, 59.4% were positive for ≥1 HPV type and 26.0% for ≥1 4-valent vaccine type. In multivariable logistic regression, factors associated with ≥1 HPV type among all participants were frequency of oral sex (odds ratio [OR] = 1.80, 95% confidence interval [CI] = 1.00-3.24), recent smoking (OR = 1.84, CI = 1.17-2.90), and sexually transmitted infection history (OR = 1.56, CI = 1.02-2.38). Factors associated with vaccine-type HPV among all participants were white versus black race (OR = 1.91, CI = 1.10-3.34) and gonorrhea history (OR = 2.52, CI = 1.45-4.38); among vaccinated participants were private versus Medicaid insurance (OR = 5.6, CI = 1.46-20.4) and private versus no insurance (OR = 15.9, CI = 3.06-83.3); and among unvaccinated participants was gonorrhea history (OR = 1.83, CI = 1.03-3.24).
CONCLUSIONS:
Anogenital HPV prevalence was high and vaccination rates low among young men 2-4 years after vaccine introduction, underscoring the urgency of increasing vaccination rates and vaccinating according to national guidelines
Possible retardation effects of quark confinement on the meson spectrum
The reduced Bethe-Salpeter equation with scalar confinement and vector gluon
exchange is applied to quark-antiquark bound states. The so called intrinsic
flaw of Salpeter equation with static scalar confinement is investigated. The
notorious problem of narrow level spacings is found to be remedied by taking
into consideration the retardation effect of scalar confinement. Good fit for
the mass spectrum of both heavy and light quarkomium states is then obtained.Comment: 14 pages in LaTex for
Simple model for quantum general relativity from loop quantum gravity
New progress in loop gravity has lead to a simple model of `general-covariant
quantum field theory'. I sum up the definition of the model in self-contained
form, in terms accessible to those outside the subfield. I emphasize its
formulation as a generalized topological quantum field theory with an infinite
number of degrees of freedom, and its relation to lattice theory. I list the
indications supporting the conjecture that the model is related to general
relativity and UV finite.Comment: 8 pages, 3 figure
Numerical Schemes for Multivalued Backward Stochastic Differential Systems
We define some approximation schemes for different kinds of generalized
backward stochastic differential systems, considered in the Markovian
framework. We propose a mixed approximation scheme for a decoupled system of
forward reflected SDE and backward stochastic variational inequality. We use an
Euler scheme type, combined with Yosida approximation techniques.Comment: 13 page
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