677 research outputs found
Efficiency of a Brownian information machine
A Brownian information machine extracts work from a heat bath through a
feedback process that exploits the information acquired in a measurement. For
the paradigmatic case of a particle trapped in a harmonic potential, we
determine how power and efficiency for two variants of such a machine operating
cyclically depend on the cycle time and the precision of the positional
measurements. Controlling only the center of the trap leads to a machine that
has zero efficiency at maximum power whereas additional optimal control of the
stiffness of the trap leads to an efficiency bounded between 1/2, which holds
for maximum power, and 1 reached even for finite cycle time in the limit of
perfect measurements.Comment: 9 pages, 2 figure
A mouse model for the Sézary syndrome
<p>Abstract</p> <p>Background</p> <p>The Sézary syndrome is an aggressive leukemic form of cutaneous T cell lymphoma and there is no cure of this disease. Until now there is no true animal model for Sézary syndrome, by which new drugs against the disease could be tested.</p> <p>Methods</p> <p>Immune deficient CB-17 SCID beige mice were injected subcutaneously with HUT78 cells, a cell line, derived from a Sézary syndrome patient. Developing tumors were analyzed by immunohistochemistry.</p> <p>Results</p> <p>Injected HUT78 cells formed tumors at the site of injection. In contrast to the Sézary syndrome in man, no malignant cells were observed in the blood of tumor bearing CB-17 SCID beige mice. The tumors appeared 44-62 days after injection and tumor bearing mice survived further 25 - 62 days until they had to be euthanized according to the guidelines of the Swiss animal protection law, since the tumors had reached the maximal allowed size.</p> <p>Conclusion</p> <p>Although the mouse model does not exactly match the human disease, it will be suited for tests of new substances for the treatment of the Sézary syndrome. The formation of an isolated tumor on the skin has the advantage that the effect of a potential drug can be directly monitored without the use of invasive methods.</p
Physiology and coronary artery disease: emerging insights from computed tomography imaging based computational modeling
Improvements in spatial and temporal resolution now permit robust high quality characterization of presence, morphology and composition of coronary atherosclerosis in computed tomography (CT). These characteristics include high risk features such as large plaque volume, low CT attenuation, napkin-ring sign, spotty calcification and positive remodeling. Because of the high image quality, principles of patient-specific computational fluid dynamics modeling of blood flow through the coronary arteries can now be applied to CT and allow the calculation of local lesion-specific hemodynamics such as endothelial shear stress, fractional flow reserve and axial plaque stress. This review examines recent advances in coronary CT image-based computational modeling and discusses the opportunity to identify lesions at risk for rupture much earlier than today through the combination of anatomic and hemodynamic information
An Analytical Study of Coupled Two-State Stochastic Resonators
The two-state model of stochastic resonance is extended to a chain of coupled
two-state elements governed by the dynamics of Glauber's stochastic Ising
model. Appropriate assumptions on the model parameters turn the chain into a
prototype system of coupled stochastic resonators. In a weak-signal limit
analytical expressions are derived for the spectral power amplification and the
signal-to-noise ratio of a two-state element embedded into the chain. The
effect of the coupling between the elements on both quantities is analysed and
array-enhanced stochastic resonance is established for pure as well as noisy
periodic signals. The coupling-induced improvement of the SNR compared to an
uncoupled element is shown to be limited by a factor four which is only reached
for vanishing input noise.Comment: 29 pages, 5 figure
Proton Differential Elliptic Flow and the Isospin-Dependence of the Nuclear Equation of State
Within an isospin-dependent transport model for nuclear reactions involving
neutron-rich nuclei, we study the first-order direct transverse flow of protons
and their second-order differential elliptic flow as a function of transverse
momentum. It is found that the differential elliptic flow of mid-rapidity
protons, especially at high transverse momenta, is much more sensitive to the
isospin dependence of the nuclear equation of state than the direct flow.
Origins of these different sensitivities and their implications to the
experimental determination of the isospin dependence of the nuclear equation of
state by using neutron-rich heavy-ion collisions at intermediate energies are
discussed.Comment: 15 pages, 6 figures. Phys. Rev. C (2001) in pres
Разработка и программная реализация алгоритма детектирования номерных знаков на изображениях
Объектом исследования является задача определения расположения номерной пластины на изображении. Цель работы – разработка и программная реализация алгоритмов детектирования номерных знаков. В процессе исследования были изучены и проанализированы существующие методы детектирования номерных знаков, методы текстурной сегментации изображений и методы предобработки изображения. В результате исследования был предложен и реализован алгоритм детектирования номерных знаков на изображениях. Программное обеспечение позволит детектировать номерные знаки автомобилей. Может быть востребовано в системах контроля и регистрации автомобилей и других видов транспортных средств.The object of study is the problem of determining the location of the license plate in the image. The work purpose – development and software implementation of algorithms for the detection of license plates. In the research process was studied and analyzed existing methods of license plate detection methods, texture segmentation of images and methods of image preprocessing. The study was proposed and implemented algorithm detecting license plates in images.The software will detect number plates of cars. It can be used in the systems of control and registration of cars and other types of vehicle
- …