Injury-induced bleeding is stopped by a hemostatic plug formation that is controlled by a complex nonlinear and spatially heterogeneous biochemical network of proteolytic enzymes called blood ...coagulation. We studied spatial dynamics of thrombin, the central enzyme of this network, by developing a fluorogenic substrate-based method for time- and space-resolved imaging of thrombin enzymatic activity. Clotting stimulation by immobilized tissue factor induced localized thrombin activity impulse that propagated in space and possessed all characteristic traits of a traveling excitation wave: constant spatial velocity, constant amplitude, and insensitivity to the initial stimulation once it exceeded activation threshold. The parameters of this traveling wave were controlled by the availability of phospholipids or platelets, and the wave did not form in plasmas from hemophilia A or C patients who lack factors VIII and XI, which are mediators of the two principal positive feedbacks of coagulation. Stimulation of the negative feedback of the protein C pathway with thrombomodulin produced nonstationary patterns of wave formation followed by deceleration and annihilation. This indicates that blood can function as an excitable medium that conducts traveling waves of coagulation.
The results of a fractal analysis of Monte Carlo AuAu events at the c.m. collision energy of
GeV on the basis of the method of the System of Equations of P-basic Coverage (SePaC) are presented. A ...MultiPhase Transport (AMPT) model is used to generate collision events. The transverse momentum
of negatively charged particles detected in the pseudorapidity range of
in events of different centrality between (0–5)
and (30–40)
is considered as the variable under study. Sets of random events and Monte Carlo fractals are compared. The difference in the behavior of the dependence of the fraction of events reconstructed as fractals on the parameters of the method for different types of data are demonstrated. Optimum values of the parameters for an analysis of AMPT AuAu events are found. It is indicated that the portion of Prtn events reconstructed as fractals depend on the centrality and multiplicity in AuAu and random events, respectively. Insignificant distinctions in the behavior of the distributions with respect to dimension
for different centrality classes are found. Two event classes differing in the shape of transverse-moment spectra are singled out among AMPT AuAu events.
Fuel rod assemblies with tight lattice bundles are considered promising for increasing the conversion rate and heat transfer in small modular reactors. The main feature of the flow in a tight lattice ...rod bundle is the formation of quasi-periodic large-scale velocity oscillations in the gap between fuel rods. These oscillations enhance mixing between the subchannels and significantly increase heat transfer between the fuel rods and the coolant. The large-scale oscillations are directly related to the pitch-to-diameter (P/D) ratio of the rod bundle and the Reynolds number. In this study, we experimentally investigate the unsteady flow structure in a gap between a flat wall and three rods with a relative pitch P/D = 1.077 using time-resolved particle image velocimetry (TR-PIV) technique. The obtained TR-PIV velocity vector fields were used to analyze flow characteristics, including two- and three-dimensional mean velocity, velocity fluctuations, and Reynolds stress profiles. We also examined the influence of the Reynolds number on flow oscillations in the gap. The spatial most energy-intensive flow modes were further analyzed using the proper orthogonal decomposition (POD) method. Our results indicate the presence of several traveling waves propagating along the flow. Modulation of flow oscillations in the gap was observed. These findings are consistent with those of other researchers.
Accelerators are used in many areas of modern science and technology (FCC-ee, CEPC, ILC, ESS, MYRRHA, etc.). One of the main elements of accelerators is the superconducting cavity based on ...high-purity niobium sheets. In addition to RRR requirements (over 300) niobium sheets for the SRF cavities should meet rather tough requirements for the grain size, recrystallization degree and mechanical properties. Development of the manufacture regimes of the niobium sheets with the required characteristics for the SRF cavities is a promising and relevant task. The paper presents the study results of the deformation route, true strain value, recrystallization heat treatment regimes influence on the structural and mechanical characteristics of the high-purity niobium sheets.
The possibility of manufacturing photovoltaic converter structures due to solid-phase reactions of substitution of Sb atoms in GaSb semiconductor wafers with As or P atoms, with simultaneous ...diffusion of Zn, is demonstrated.
The possibility of controlling the composition of lateral nanowires by the method of growth under quasi-equilibrium conditions in a quasi-closed volume from indium, phosphorus, and arsenic vapors ...with Au catalyst in the “vapor-liquid-solid” mechanism has been demonstrated for the first time. It has been experimentally shown that the additional presence of arsenic in the indium-phosphorus source leads to the coalescence of catalytic gold droplets at the initial stage of the growth, which determines the further morphology and growth kinetics of nanostructures. An additional formation of indium phosphide nanostructures with a composition different from that of the main nanowires was found. The results of the studies expand the possibilities of the developed method for obtaining lateral nanowires on gallium arsenide substrates.
Monte Carlo (MC)
events at an energy of
= 200 GeV, obtained using the AMPT generator, MC fractals, and events with randomly distributed particles are analyzed by the
method. The dependence of the ...portion
of the events under study, defined as fractals, on the method parameter
is investigated. It has been established that the hypotheses of independent and dependent formation of fractals correspond to different regions of behavior of
for AMPT
events. The
method makes it possible to extract AMPT
events with equal fractal dimensions
at different levels. The distribution of events by
are different for used hypotheses. Events identified by the hypothesis of independent devision have a group of leading particles according to
,
and the remaining ones exhibit exponential behavior of the
spectrum. The use of background suppression criteria describing the statistical characteristics of structures at different levels showed that a significant part of the events identified by the independent devision hypothesis have the same structures and can be interpreted as fractals. Events reconstructed by the dependent devision hypothesis are suppressed.
First Globus-M2 Results Bakharev, N. N.; Balachenkov, I. M.; Chernyshev, F. V. ...
Plasma physics reports,
07/2020, Letnik:
46, Številka:
7
Journal Article
Recenzirano
Globus-M2—a new 1-Tesla spherical tokamak—was recently launched. The main features and research directions of this machine in scope of fusion–fission reactor development are described. Main results ...of the first experimental campaign with toroidal magnetic field up to 0.73 T and plasma current up to 0.33 MA are discussed. Significant improvement of the discharge parameters as compared to Globus-M was achieved. Plasma total stored energy higher than 7 kJ was obtained. Energy confinement time increase was consistent with predictions by spherical tokamak scalings. Toroidal Alfvén eigenmode-induced losses decrease with increase of plasma current and toroidal magnetic field. For the first time, LHCD with the toroidal wave slowing-down was successfully used at a spherical tokamak.
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