2,068,663 research outputs found
Formation of regular spatial patterns in ratio-dependent predator-prey model driven by spatial colored-noise
Results are reported concerning the formation of spatial patterns in the
two-species ratio-dependent predator-prey model driven by spatial
colored-noise. The results show that there is a critical value with respect to
the intensity of spatial noise for this system when the parameters are in the
Turing space, above which the regular spatial patterns appear in two
dimensions, but under which there are not regular spatial patterns produced. In
particular, we investigate in two-dimensional space the formation of regular
spatial patterns with the spatial noise added in the side and the center of the
simulation domain, respectively.Comment: 4 pages and 3 figure
Viral Hepatitis And Enzyme Study
The present study was undertaken in sixty patients of viral hepatitis of both sexes ranging 20 to 60 yrs. of age to compare serum levels or 5’Nucleotidase, Alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase & serum bilirubin. Forty of clinically healthy subjects were taken as control group. These were patient’s attendants without any evidence of liver disease so as to equlibriate the socioeconomic status and age. The study group patients were either admitted to Rajindra Hospital, Patiala, or attending the OPD. A detailed clinical examination was carried out in all as per plan mentioned in materials & methods. Diagnosis of these patients was based on clinical findings. Endeavour was to find out a single enzyme marker which is most specific and sensitive parameter out of all above. It was later concluded that value of 5’ NT was highly significant as compared to ALP. A positive correlation was observed between AST, ALT & serum bilirubin level. But 5’ NT showed no correlation with aminotransferases
Shelling the Voronoi interface of protein-protein complexes predicts residue activity and conservation
The accurate description of protein-protein interfaces remains a challenging task. Traditional criteria, based on atomic contacts or changes in solvent accessibility, tend to over or underpredict the interface itself and cannot discriminate active from less relevant parts. A recent simulation study by Mihalek and co-authors (2007, JMB 369, 584-95) concluded that active residues tend to be `dry', that is, insulated from water fluctuations. We show that patterns of `dry' residues can, to a large extent, be predicted by a fast, parameter-free and purely geometric analysis of protein interfaces. We introduce the shelling order of Voronoi facets as a straightforward quantitative measure of an atom's depth inside an interface. We analyze the correlation between Voronoi shelling order, dryness, and conservation on a set of 54 protein-protein complexes. Residues with high shelling order tend to be dry; evolutionary conservation also correlates with dryness and shelling order but, perhaps not surprisingly, is a much less accurate predictor of either property. Voronoi shelling order thus seems a meaningful and efficient descriptor of protein interfaces. Moreover, the strong correlation with dryness suggests that water dynamics within protein interfaces may, in first approximation, be described by simple diffusion models
Tamsulosin � turn a round
Tamsulosin is a sulfamoylphen-ethylamine derivative, a potent and a selective antagonist of Alpha-1A adrenoceptor. It�s approved in the treatment of LUTS in BPH disease, being a specific Alpha -1A blocker it does not interfere much with the cardiovascular system. Though an age old molecule but still it�s a friendly drug to most of the physicians. Even the recent studies found its as efficacious to some of the newer molecules in the group
Solvable senescence model with positive mutations
We build upon our previous analytical results for the Penna model of
senescence to include positive mutations. We investigate whether a small but
non-zero positive mutation rate gives qualitatively different results to the
traditional Penna model in which no positive mutations are considered. We find
that the high-lifespan tail of the distribution is radically changed in
structure, but that there is not much effect on the bulk of the population. Th
e mortality plateau that we found previously for a stochastic generalization of
the Penna model is stable to a small positive mutation rate.Comment: 3 figure
Force generation in small ensembles of Brownian motors
The motility of certain gram-negative bacteria is mediated by retraction of
type IV pili surface filaments, which are essential for infectivity. The
retraction is powered by a strong molecular motor protein, PilT, producing very
high forces that can exceed 150 pN. The molecular details of the motor
mechanism are still largely unknown, while other features have been identified,
such as the ring-shaped protein structure of the PilT motor. The surprisingly
high forces generated by the PilT system motivate a model investigation of the
generation of large forces in molecular motors. We propose a simple model,
involving a small ensemble of motor subunits interacting through the
deformations on a circular backbone with finite stiffness. The model describes
the motor subunits in terms of diffusing particles in an asymmetric,
time-dependent binding potential (flashing ratchet potential), roughly
corresponding to the ATP hydrolysis cycle. We compute force-velocity relations
in a subset of the parameter space and explore how the maximum force (stall
force) is determined by stiffness, binding strength, ensemble size, and degree
of asymmetry. We identify two qualitatively different regimes of operation
depending on the relation between ensemble size and asymmetry. In the
transition between these two regimes, the stall force depends nonlinearly on
the number of motor subunits. Compared to its constituents without
interactions, we find higher efficiency and qualitatively different
force-velocity relations. The model captures several of the qualitative
features obtained in experiments on pilus retraction forces, such as roughly
constant velocity at low applied forces and insensitivity in the stall force to
changes in the ATP concentration.Comment: RevTex 9 pages, 4 figures. Revised version, new subsections in Sec.
III, removed typo
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