4,143 research outputs found
Pathophysiological aspects of the problem of prolonged hypokinesia
The changes in man's acitivity due to modern life with automation and sedentary activities and man's exploration of space in a state of weightlessness have accentuated the importance of hypokinesia. The pathogenesis of hypokinesia is discussed. Experiments and results made on man and animals are included
Life in motion, in motion!
A 120 day limited mobility experiment with young male rats and its results, including retarded growth and degenerative changes in the cardiac muscle, are described. A 120 day strict bedrest experiment with 10 human volunteers and its results are described and discussed. Early subjective complaints, subsequent adaptation and eventual progressive changes in excitability and reactivity, reduction in functional capability of the cerebral cortex, and disturbances in water-salt, protein and fat metabolism, including development of precursors of atherosclerosis, as well as poor results of the orthostatic test after 4 months, are presented. These results are explained as applied to sedentary workers and recommendations are given for such persons to exercise in the morning, at work and in the evening in order to prevent hypokinesis and its physical, mental and physiological effects
Ideas of I. M. Sechenov in aviation and space medicine
The contributions I. M. Sechenov (19th century) made to modern physiology are described, including his studies on gases in the blood (O2 and CO2), and how these studies were the basic building blocks of current efforts in aviation and space medicine. Sechenov also studied hypokinesia, which is becoming important in long duration space flights
Peculiarities of internet-marketing for B2B
Nowadays many companies use different tools to attract customers such as press (newspapers, magazines), audio-visual aids (TV, radio), indoor and outdoor advertisements, event-marketing, PR etc. Internet is a tool that emerged with the development of scientific and technical progress and replaced the traditional marketing tools
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Correlation between heavy flavour production and multiplicity in string fusion approach
The multiplicity dependence of heavy flavour production in pp-collisions at LHC energies is studied in the framework of string fusion approach. We applied a Monte Carlo model [1, 2], with the string configurations simulating event-by-event. We assumed that the heavy flavour yield is proportional to the number of initial strings, whereas a total charged particle multiplicity is influenced by the string fusion process and can be obtained according to the standard string fusion prescriptions. We show that under this assumption the faster-than-linear growth of the open charm production, observed in experiment [3], can be related to the reduction of the total multiplicity due to string overlapping and fusion. The influence of this effect on forward-backward correlations involving heavy flavours is also discussed
The effect of hypodynamia on mineral and protein metabolism in calcified tissues of the maxillodental system (experimental radioisotope study)
Mineral and protein metabolism was studied in experiments on 60 white rats, using P-32 and Ca-45 uptake in the mineral fractions, 2C-14-glycine in the protein fractions, and P-32 in both fractions of calcified tissues as indices over a 100 day period of experimental hypodynamia. Combined alterations in mineral and protein metabolism occurred in the calcified tissues of the experimental animals. The most pronounced changes were found in P-32 and 2C-14-glycine metabolism. In the incisors and femoral bones, these alterations occurred in two phases: P-32 and 2C-14-glycine uptake first increased, then decreased. Changes in Ca-45 metabolism were less pronounced, particularly in the initial period of the experiment. A marked reduction in P-32, Ca-45, and 2C-14-glycine uptake was found in various fractions of the calcified tissues on the 100th day of experimental hypodynamia
Structure and mass transport characteristics of the surface of gadolinium-doped ceria nanocrystals: Molecular dynamics study
Surface of CGO nanocrystals in a vacuum was investigated by MD method in a wide temperature range with five different potentials. Temperature dependences of distances between cations in near-surface layers in the direction along the surface and to the nanocrystal center were studied in detail. Surface area ratio S(100)/S(111) for equilibrium shape of truncated octahedron has maximum for nanocrystals of 6000-12,000 ions. Surface ion displacement was decomposed on the path along the surface and into the bulk of nanocrystal. The diffusion of surface ions in the entire temperature range has predominantly two-dimensional character, regardless of potentials and the dopant concentration X. Anion diffusion coefficients on the surface and in the bulk were compared, they coincide at T < 1200 K for X ≥ 0.05. For a system with X = 0.01 anion migration energies of 0.82 eV and 0.77 eV, and anti-Frenkel pair formation energies of 3.01 eV and 4.04 eV on the surface and in the bulk, respectively, were obtained. © 2013 Elsevier B.V
Implications of R-parity violating supersymmetry for atomic and hadronic EDMs
We calculate the electric dipole moments (EDM) of the neutral Hg(199) atom,
deuteron, nucleons and neutral hyperons Lambda, Sigma(0) and Xi(0) in the
framework of a generic SUSY model without R-parity conservation (RPV SUSY) on
the basis of the SU(3) version of chiral perturbation theory (ChPT). We
consider CP-violation in the hadronic sector induced by the chromoelectric
quark dipole moments and CP-violating 4-quark effective interactions. From the
null experimental results on the neutron and Hg(199) atom EDMs we derive limits
on the imaginary parts of certain products Im(lambda' lambda'*) of the
trilinear RPV-couplings and demonstrate that they are more stringent than those
existing in the literature. Using these limits we give predictions for the EDMs
of neutral hyperons.
We also estimate the prospects of future storage ring experiments on the
deuteron EDM and show that the expected improvement of the above limits in
these experiments may reach several orders of magnitude.Comment: 11 pages, 1 figure, accepted for publication in Phys. Rev.
Estimation of synchronous generator participation in low-frequency oscillations damping based on synchronized phasor measurements
Large-scale centralized power systems interconnected by weak tie-lines is a typical feature of the state-of-the-industry power engineering. Another trend is distributed generation units integration with the resulting decrease of power system inertia constant and increasing sensitivity to small disturbances. In particular, in the case of significant power imbalance, periodic low-frequency oscillations of power system performance parameters may arise. Low frequency oscillations in power systems are inherently non-linear and non-stationary processes representing a superposition of numerous rotating masses movement components having mutual influence in a power region or power center. These situations imply the crucial role of monitoring each generator damping capability which is determined by the adjustment of the system regulators in use. To estimate the synchronous generator capability to maintain synchronous operation under deviating frequency and load angle conditions synchronizing torque and corresponding synchronizing power are proposed to be used. The possibility to determine the synchronous machine synchronizing power is subject to the presence of the load angle variation data with the techniques for defining load angle without direct measurement using a system of assumptions have been analyzed. Numerous simulations have shown that the effect of assumptions can be evaluated as acceptable. The main focus of the paper is the analysis of synchronizing power corresponding to the actual generator involved in the oscillations which had arisen after a disturbance in the Unified Energy System of Russia. The supposed cause of the oscillations is improper automatic excitation controller operation. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen
Mechanisms of water-salt metabolism disturbances in dogs subjected to six month hypokinesia
Water-salt metabolism in dogs during prolonged restricted motor activity (hypokinesia) was investigated. It was found that hydration occurred and fluid was redistributed between the extra- and intra-cellular sectors. Also, electrolyte excretion rose, and magnetism and calcium metabolism changed significantly. It is concluded that the forces caused by muscle strain proper (which was decreased under conditions of hypokinesia) influence the state of bone metabolism
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