22,949 research outputs found
Multiscale modelling of fluid and solute transport in soft tissues and microvessels
This study focuses on the movement of particles and extracellular fluid in soft tissues and microvessels. It analyzes modeling applications in biological and physiological fluids at a range of different length scales: from between a few tens to several hundred nanometers, on the endothelial glycocalyx and its effects on interactions between blood and the vessel wall; to a few micrometers, on movement of blood cells in capillaries and transcapillary exchange; to a few millimetres and centimetres, on extracellular matrix deformation and interstitial fluid movement in soft tissues. Interactions between blood cells and capillary wall are discussed when the sizes of the two are of the same order of magnitude, with the glycocalyx on the endothelial and red cell membranes being considered. Exchange of fluid, solutes, and gases by microvessels are highlighted when capillaries have counter-current arrangements. This anatomical feature exists in a number of tissues and is the key in the renal medulla on the urinary concentrating mechanism. The paper also addresses an important phenomenon on the transport of macromolecules. Concentration polarization of hyaluronan on the synovial lining of joint cavities is presented to demonstrate how the mechanism works in principle and how model predictions agree to experimental observations quantitatively
Image classification by visual bag-of-words refinement and reduction
This paper presents a new framework for visual bag-of-words (BOW) refinement
and reduction to overcome the drawbacks associated with the visual BOW model
which has been widely used for image classification. Although very influential
in the literature, the traditional visual BOW model has two distinct drawbacks.
Firstly, for efficiency purposes, the visual vocabulary is commonly constructed
by directly clustering the low-level visual feature vectors extracted from
local keypoints, without considering the high-level semantics of images. That
is, the visual BOW model still suffers from the semantic gap, and thus may lead
to significant performance degradation in more challenging tasks (e.g. social
image classification). Secondly, typically thousands of visual words are
generated to obtain better performance on a relatively large image dataset. Due
to such large vocabulary size, the subsequent image classification may take
sheer amount of time. To overcome the first drawback, we develop a graph-based
method for visual BOW refinement by exploiting the tags (easy to access
although noisy) of social images. More notably, for efficient image
classification, we further reduce the refined visual BOW model to a much
smaller size through semantic spectral clustering. Extensive experimental
results show the promising performance of the proposed framework for visual BOW
refinement and reduction
The , decays in the perturbative QCD approach
Nonleptonic two body decays including radially excited or
mesons in the final state are studied using the perturbative QCD
approach based on factorization. The charmonium distribution amplitudes
are extracted from the Schrdinger states for the
harmonic oscillator potential. Utilizing these distribution amplitudes, we
calculate the numerical results of the
transition form factors and branching fractions of decays. The ratio between two decay modes and is compatible with the experimental
data within uncertainties, which indicate that the harmonic oscillator wave
functions for and work well. It is found that the
branching fraction of , which is dominated by the
twist-3 charmonium distribution amplitude, can reach the order of . We
hope it can be measured soon in the LHCb experiment.Comment: 9 pages, 3 figures,3 Table
Two dimensional scaling of resistance in flux flow region in thin films
The resistance of thin films has been measured when the
angle between the applied fields and -plane of the film is changed
continuously at various temperatures. Under various magnetic fields, the
resistance can be well scaled in terms of the c-axis component of the applied
fields at the same temperature in the whole angle range. Meanwhile, we show
that the measurement of resistance in this way is a complementary method to
determine the growth orientation of the anisotropic high- superconductors.Comment: 11 pages, 8 figures. Have been published in Physica
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