2,702 research outputs found
Morphology and Orientation Selection of Non-Metallic Inclusions in Electrified Molten Metal
The effect of electric current on morphology and orientation selection of non-metallic inclusions in molten metal has been investigated using theoretical modelling and numerical calculation. Two geometric factors, namely the circularity (fc) and alignment ratio (fe) were introduced to describe the inclusions shape and configuration. Electric current free energy was calculated and the values were used to determine the thermodynamic preference between different microstructures. Electric current promotes the development of inclusion along the current direction by either expatiating directional growth or enhancing directional agglomeration. Reconfiguration of the inclusions to reduce the system electric resistance drives the phenomena. The morphology and orientation selection follows the routine to reduce electric free energy. The numerical results are in agreement with our experimental observations
Tumor necrosis factor reduces Plasmodium falciparum growth and activates calcium signaling in human malaria parasites
Background:
Plasmodium has a complex biology including the ability to interact with host signals modulating their function through cellular machinery. Tumor necrosis factor (TNF) elicits diverse cellular responses including effects in malarial pathology and increased infected erythrocyte cytoadherence. As TNF levels are raised during P. falciparum infection we have investigated whether it has an effect on the parasite asexual stage.
Methods:
Flow cytometry, spectrofluorimetric determinations, confocal microscopy and PCR real time quantifications were employed for characterizing TNF induced effects and membrane integrity verified by wheat germ agglutinin staining.
Results:
TNF is able to decrease intracellular parasitemia, involving calcium as a second messenger of the pathway. Parasites incubated for 48h with TNF showed reduced erythrocyte invasion. Thus, TNF induced rises in intracellular calcium concentration, which were blocked by prior addition of the purinergic receptor agonists KN62 and A438079, or interfering with intra- or extracellular calcium release by thapsigargin or EGTA (ethylene glycol tetraacetic acid). Importantly, expression of PfPCNA1 which encodes the Plasmodium falciparum Proliferating-Cell Nuclear Antigen 1, decreased after P. falciparum treatment of TNF (tumor necrosis factor) or 6-Bnz cAMP (N6-Benzoyladenosine-3′,5′-cyclic monophosphate sodium salt).
Conclusions:
This is potentially interesting data showing the relevance of calcium in down regulating a gene involved in cellular proliferation, triggered by TNF.
General significance:
The data show that Plasmodium may subvert the immunological system and use TNF for the control of its proliferation within the vertebrate host
Pulse Dynamics in a Chain of Granules With Friction
We study the dynamics of a pulse in a chain of granules with friction. We
present theories for chains of cylindrical granules (Hertz potential with
exponent ) and of granules with other geometries (). Our results are
supported via numerical simulations for cylindrical and for spherical granules
().Comment: Submitted to PR
Stability of complex hyperbolic space under curvature-normalized Ricci flow
Using the maximal regularity theory for quasilinear parabolic systems, we
prove two stability results of complex hyperbolic space under the
curvature-normalized Ricci flow in complex dimensions two and higher. The first
result is on a closed manifold. The second result is on a complete noncompact
manifold. To prove both results, we fully analyze the structure of the
Lichnerowicz Laplacian on complex hyperbolic space. To prove the second result,
we also define suitably weighted little H\"{o}lder spaces on a complete
noncompact manifold and establish their interpolation properties.Comment: Some typos in version 2 are correcte
Electronic structure study of double perovskites FeReO (A=Ba,Sr,Ca) and SrMoO (M=Cr,Mn,Fe,Co) by LSDA and LSDA+U
We have implemented a systematic LSDA and LSDA+U study of the double
perovskites FeReO (A=Ba,Sr,Ca) and SrMoO
(M=Cr,Mn,Fe,Co) for understanding of their intriguing electronic and magnetic
properties. The results suggest a ferrimagnetic (FiM) and half-metallic (HM)
state of FeReO (A=Ba,Sr) due to a pdd- coupling between the
down-spin Re/Fe orbitals via the intermediate O
ones, also a very similar FiM and HM state of SrFeMoO.
In contrast, a decreasing Fe component at Fermi level () in the
distorted CaFeReO partly accounts for its nonmetallic behavior,
while a finite - coupling between the down-spin
Re/Fe orbitals being present at serves to
stabilize its FiM state. For SrCrMoO compared with
SrFeMoO, the coupling between the down-spin Mo/Cr
orbitals decreases as a noticeable shift up of the Cr 3d
levels, which is likely responsible for the decreasing value and weak
conductivity. Moreover, the calculated level distributions indicate a
Mn(Co)/Mo ionic state in SrMnMoO
(SrCoMoO), in terms of which their antiferromagnetic insulating
ground state can be interpreted. While orbital population analyses show that
owing to strong intrinsic pd covalence effects, SrMoO
(M=Cr,Mn,Fe,Co) have nearly the same valence state combinations, as accounts
for the similar M-independent spectral features observed in them.Comment: 21 pages, 3 figures. to be published in Phys. Rev. B on 15th Se
The Strange Parton Distribution of the Nucleon: Global Analysis and Applications
The strangeness degrees of freedom in the parton structure of the nucleon are
explored in the global analysis framework, using the new CTEQ6.5 implementation
of the general mass perturbative QCD formalism of Collins. We systematically
determine the constraining power of available hard scattering experimental data
on the magnitude and shape of the strange quark and anti-quark parton
distributions. We find that current data favor a distinct shape of the strange
sea compared to the isoscalar non-strange sea. A new reference parton
distribution set, CTEQ6.5S0, and representative sets spanning the allowed
ranges of magnitude and shape of the strange distributions, are presented. Some
applications to physical processes of current interest in hadron collider
phenomenology are discussed.Comment: 19 pages; revised version submitted to JHE
Fast Searching in Packed Strings
Given strings and the (exact) string matching problem is to find all
positions of substrings in matching . The classical Knuth-Morris-Pratt
algorithm [SIAM J. Comput., 1977] solves the string matching problem in linear
time which is optimal if we can only read one character at the time. However,
most strings are stored in a computer in a packed representation with several
characters in a single word, giving us the opportunity to read multiple
characters simultaneously. In this paper we study the worst-case complexity of
string matching on strings given in packed representation. Let be
the lengths and , respectively, and let denote the size of the
alphabet. On a standard unit-cost word-RAM with logarithmic word size we
present an algorithm using time O\left(\frac{n}{\log_\sigma n} + m +
\occ\right). Here \occ is the number of occurrences of in . For this improves the bound of the Knuth-Morris-Pratt algorithm.
Furthermore, if our algorithm is optimal since any
algorithm must spend at least \Omega(\frac{(n+m)\log
\sigma}{\log n} + \occ) = \Omega(\frac{n}{\log_\sigma n} + \occ) time to
read the input and report all occurrences. The result is obtained by a novel
automaton construction based on the Knuth-Morris-Pratt algorithm combined with
a new compact representation of subautomata allowing an optimal
tabulation-based simulation.Comment: To appear in Journal of Discrete Algorithms. Special Issue on CPM
200
An Improved Description of the Dielectric Breakdown in Oxides Based on a Generalized Weibull distribution
In this work, we address modal parameter fluctuations in statistical
distributions describing charge-to-breakdown and/or
time-to-breakdown during the dielectric breakdown regime of
ultra-thin oxides, which are of high interest for the advancement of electronic
technology. We reobtain a generalized Weibull distribution (-Weibull), which
properly describes data when oxide thickness fluctuations are
present, in order to improve reliability assessment of ultra-thin oxides by
time-to-breakdown extrapolation and area scaling. The incorporation
of fluctuations allows a physical interpretation of the -Weibull
distribution in connection with the Tsallis statistics. In support to our
results, we analyze data of SiO-based MOS devices obtained
experimentally and theoretically through a percolation model, demonstrating an
advantageous description of the dielectric breakdown by the -Weibull
distribution.Comment: 5 pages, 3 figure
Squeezing in multi-mode nonlinear optical state truncation
In this paper, we show that multi-mode qubit states produced via nonlinear
optical state truncation driven by classical external pumpings exhibit
squeezing condition. We restrict our discussions to the two and three-mode
cases.Comment: 7 pages, 5 eps figures. Revised manuscript. Accepted for publication
in Phys. Lett.
Bi-Objective Community Detection (BOCD) in Networks using Genetic Algorithm
A lot of research effort has been put into community detection from all
corners of academic interest such as physics, mathematics and computer science.
In this paper I have proposed a Bi-Objective Genetic Algorithm for community
detection which maximizes modularity and community score. Then the results
obtained for both benchmark and real life data sets are compared with other
algorithms using the modularity and MNI performance metrics. The results show
that the BOCD algorithm is capable of successfully detecting community
structure in both real life and synthetic datasets, as well as improving upon
the performance of previous techniques.Comment: 11 pages, 3 Figures, 3 Tables. arXiv admin note: substantial text
overlap with arXiv:0906.061
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