502 research outputs found
Sensomotor integration features in skilled female boxers
The paper considers features of sensomotor integration of visuomotor reactions in female boxers. It is found that sportswomen have quicker reactions, but make more mistakes in complex choice reaction. Sensomotor integration of sensomotor reaction into functional systems of activity in female boxers is also associated more with accuracy of responsive actions than in reaction rate. © JPES
Antimatter spectra from a time-dependent modeling of supernova remnants
We calculate the energy spectra of cosmic rays (CR) and their secondaries
produced in a supernova remnant (SNR), taking into account the time-dependence
of the SNR shock. We model the trajectories of charged particles as a random
walk with a prescribed diffusioncoefficient, accelerating the particles at each
shock crossing. Secondary production by CRs colliding with gas is included as a
Monte Carlo process. We find that SNRs produce less antimatter than suggested
previously: The positron/electron ratio and the antiproton/proton ratio are a
few percent and few , respectively. Both ratios do not rise
with energy.Comment: 4 pages, 4 eps figures; v2: results for time-dependent magnetic field
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Cobalt(II) and copper(II) complexes with carboxylic acids, imidazole, and 2-methylimidazole
The compositions of [MIm(MeIm)x]L complexes synthesized by the reaction of cobalt(II) and copper(II) fumarates ML · nH2O with imidazole (Im) and 2-methylimidazole (MeIm) were determined. The thermal decomposition of the salts was analyzed, and the pyridine nitrogen atom of imidazole and the oxygen atoms of carboxyl anions were shown to participate in complexation using electronic absorption spectra and IR spectra. The composition and stability of cobalt(II) and copper(II) imidazolatesuccinate complexes in an aqueous solution were determined photometrically and spectrophotometrically, and their higher stability in comparison with monoligand complexes was demonstrated
Bioinformatics analysis of disordered proteins in prokaryotes
<p>Abstract</p> <p>Background</p> <p>A significant number of proteins have been shown to be intrinsically disordered, meaning that they lack a fixed 3 D structure or contain regions that do not posses a well defined 3 D structure. It has also been proven that a protein's disorder content is related to its function. We have performed an exhaustive analysis and comparison of the disorder content of proteins from prokaryotic organisms (i.e., superkingdoms Archaea and Bacteria) with respect to functional categories they belong to, i.e., Clusters of Orthologous Groups of proteins (COGs) and groups of COGs-Cellular processes (Cp), Information storage and processing (Isp), Metabolism (Me) and Poorly characterized (Pc).</p> <p>We also analyzed the disorder content of proteins with respect to various genomic, metabolic and ecological characteristics of the organism they belong to. We used correlations and association rule mining in order to identify the most confident associations between specific modalities of the characteristics considered and disorder content.</p> <p>Results</p> <p>Bacteria are shown to have a somewhat higher level of protein disorder than archaea, except for proteins in the Me functional group. It is demonstrated that the Isp and Cp functional groups in particular (L-repair function and N-cell motility and secretion COGs of proteins in specific) possess the highest disorder content, while Me proteins, in general, posses the lowest. Disorder fractions have been confirmed to have the lowest level for the so-called order-promoting amino acids and the highest level for the so-called disorder promoters.</p> <p>For each pair of organism characteristics, specific modalities are identified with the maximum disorder proteins in the corresponding organisms, e.g., high genome size-high GC content organisms, facultative anaerobic-low GC content organisms, aerobic-high genome size organisms, etc. Maximum disorder in archaea is observed for high GC content-low genome size organisms, high GC content-facultative anaerobic or aquatic or mesophilic organisms, etc. Maximum disorder in bacteria is observed for high GC content-high genome size organisms, high genome size-aerobic organisms, etc.</p> <p>Some of the most reliable association rules mined establish relationships between high GC content and high protein disorder, medium GC content and both medium and low protein disorder, anaerobic organisms and medium protein disorder, Gammaproteobacteria and low protein disorder, etc. A web site <it>Prokaryote Disorder Database </it>has been designed and implemented at the address <url>http://bioinfo.matf.bg.ac.rs/disorder</url>, which contains complete results of the analysis of protein disorder performed for 296 prokaryotic completely sequenced genomes.</p> <p>Conclusions</p> <p>Exhaustive disorder analysis has been performed by functional classes of proteins, for a larger dataset of prokaryotic organisms than previously done. Results obtained are well correlated to those previously published, with some extension in the range of disorder level and clear distinction between functional classes of proteins. Wide correlation and association analysis between protein disorder and genomic and ecological characteristics has been performed for the first time. The results obtained give insight into multi-relationships among the characteristics and protein disorder. Such analysis provides for better understanding of the evolutionary process and may be useful for taxon determination. The main drawback of the approach is the fact that the disorder considered has been predicted and not experimentally established.</p
One-pot synthesis of (R)-convolutamydine A involving in situ chiral organocatalyst formation
The application of a convenient one-pot synthetic
strategy, utilizing an in situ formed organocatalyst, to
the enantioselective synthesis of anti-leukaemia agent
(R)-convolutamydine A has been demonstrated
The evolution of luminosity, colour and the mass-to-luminosity ratio of Galactic open clusters: comparison of discrete vs. continuous IMF models
(abridged) We found in previous studies that standard Simple Stellar
Population (SSP) models are unable to describe or explain the colours of
Galactic open clusters both in the visible and in the NIR spectral range. (...)
We construct a numerical SSP-model, with an underlying Salpeter IMF, valid
within an upper and lower stellar mass range, and with total masses
typical of open clusters. We assume that the mass
loss from a cluster is provided by mass loss from evolved stars and by the
dynamical evaporation of low-mass members due to two-body relaxation. The data
for the latter process were scaled to the models from high-resolution N-body
calculations. We also investigate how a change of the -limit influences
magnitudes and colours of clusters of a given mass and derive a necessary
condition for a luminosity and colour flash. The discreteness of the IMF leads
to bursts in magnitude and colour of model clusters at moments when red
supergiants or giants appear and then die. The amplitude of the burst depends
on the cluster mass and on the spectral range; it is strongly increased in the
NIR compared to optical passbands. In the discrete case, variations of the
parameter are able to substantially change the magnitude-age and
-age relations. For the colours, the lowering of considerably
amplifies the discreteness effect. The influence of dynamical mass loss on
colour and magnitude is weak, although it provides a change of the slopes of
the considered relations, improving their agreement with observations. For the
Galactic open clusters we determined luminosity and tidal mass independent of
each other. The derived mass-to-luminosity ratio shows, on average, an increase
with cluster age in the optical, but gradually declines with age in the NIR.
The observed flash statistics can be used to constrain in open clusters.Comment: 15 pages, 13 figures, accepted for publication in Astronomy and
Astrophysic
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