348 research outputs found
Elasticity of Semiflexible Biopolymer Networks
We develop a model for gels and entangled solutions of semiflexible
biopolymers such as F-actin. Such networks play a crucial structural role in
the cytoskeleton of cells. We show that the rheologic properties of these
networks can result from nonclassical rubber elasticity. This model can explain
a number of elastic properties of such networks {\em in vitro}, including the
concentration dependence of the storage modulus and yield strain.Comment: Uses RevTeX, full postscript with figures available at
http://www.umich.edu/~fcm/preprints/agel/agel.htm
Unbounded solutions for systems with hysteretic nonlinearity
The work is dedicated to study of the dynamics of model systems that are described by differential equations with additive hysteretic nonlinearities in the case when a hysteretic loop bypass clockwise. In particular, for the model of the harmonic oscillator with hysteretic external force the conditions for existence of unbounded solutions are obtained. For the model of harmonic oscillator with a dry (Coulomb) and viscous friction under external hysteretic affection we obtained a set of conditions that ensure the self-oscillation mode. The numerical examples that illustrate the results of this work are also presented.This work is supported by the RFBR grant No 16-08-00312, 17-01-00251
Hysteretic damper based on Bouc-Wen model
In the presented work we consider the dynamics of the mechanical system under internal force with a damper taking into account the hysteretic nature of the damper. As a mathematical model of this hysteretic damper we consider the Bouc-Wen model. The obtained numerical results in the form of the force transfer function demonstrates the efficiency of the hysteretic damper in comparison with the nonlinear viscous damper.This work is supported by the RFBR grant No 16-08-00312, 17-01-00251
Correlation of Beam Electron and LED Signal Losses under Irradiation and Long-term Recovery of Lead Tungstate Crystals
Radiation damage in lead tungstate crystals reduces their transparency. The
calibration that relates the amount of light detected in such crystals to
incident energy of photons or electrons is of paramount importance to
maintaining the energy resolution the detection system. We report on tests of
lead tungstate crystals, read out by photomultiplier tubes, exposed to
irradiation by monoenergetic electron or pion beams. The beam electrons
themselves were used to measure the scintillation light output, and a blue
light emitting diode (LED) was used to track variations of crystals
transparency. We report on the correlation of the LED measurement with
radiation damage by the beams and also show that it can accurately monitor the
crystals recovery from such damage.Comment: 9 pages, 6 figures, LaTeX2
Comparison of Radiation Damage in Lead Tungstate Crystals under Pion and Gamma Irradiation
Studies of the radiation hardness of lead tungstate crystals produced by the
Bogoroditsk Techno-Chemical Plant in Russia and the Shanghai Institute of
Ceramics in China have been carried out at IHEP, Protvino. The crystals were
irradiated by a 40-GeV pion beam. After full recovery, the same crystals were
irradiated using a -ray source. The dose rate profiles along
the crystal length were observed to be quite similar. We compare the effects of
the two types of radiation on the crystals light output.Comment: 10 pages, 8 figures, Latex 2e, 28.04.04 - minor grammatical change
LED Monitoring System for the BTeV Lead Tungstate Crystal Calorimeter Prototype
We report on the performance of a monitoring system for a prototype
calorimeter for the BTeV experiment that uses Lead Tungstate crystals coupled
with photomultiplier tubes. The tests were carried out at the 70 GeV
accelerator complex at Protvino, Russia.Comment: 12 pages, 8 figures, LaTeX2e, revised versio
Design and performance of LED calibration system prototype for the lead tungstate crystal calorimeter
A highly stable monitoring system based on blue and red light emitting diodes
coupled to a distribution network comprised of optical fibers has been
developed for an electromagnetic calorimeter that uses lead tungstate crystals
readout with photomultiplier tubes. We report of the system prototype design
and on the results of laboratory tests. Stability better than 0.1% (r.m.s.) has
been achieved during one week of prototype operation.Comment: 10 pages, 6 figures, LaTeX2
First study of radiation hardness of lead tungstate crystals at low temperatures
The electromagnetic calorimeter of PANDA at the FAIR facility will rely on an
operation of lead tungstate (PWO) scintillation crystals at temperatures near
-25 deg.C to provide sufficient resolution for photons in the energy range from
8 GeV down to 10 MeV. Radiation hardness of PWO crystals was studied at the
IHEP (Protvino) irradiation facility in the temperature range from room
temperature down to -25 deg.C. These studies have indicated a significantly
different behaviour in the time evolution of the damaging processes well below
room temperature. Different signal loss levels at the same dose rate, but at
different temperatures were observed. The effect of a deep suppression of the
crystal recovery process at temperatures below
0 deg.C has been seen.Comment: 10 pages 7 figure
Клиническое исследование отечественного фибринселективного тромболитического препарата Фортелизин® (III фаза)
The clinical trial of fibrinselective thrombolytic agent Fortelyzin® (III phase) showed the comparative efficacy and safety with Actilyse® in patients with acute myocardial infarction and obtained data permitted to recommend it for clinical usage.Проведенное исследование лекарственного препарата Фортелизин®, вводимого болюсно и болюсно-инфузионно у больных с острым инфарктом миокарда с подъемом сегмента ST, показало сравнимую с Актилизе® эффективность и безопасность исследуемого препарата и позволило рекомендовать его для медицинского применения
Development of a Momentum Determined Electron Beam in the 1 -45 GeV Range
A beam line for electrons with energies in the range of 1 to 45 GeV, low
contamination of hadrons and muons and high intensity up to 10^6 per
accelerator spill at 27 GeV was setup at U70 accelerator in Protvino, Russia. A
beam tagging system based on drift chambers with 160 micron resolution was able
to measure relative electron beam momentum precisely. The resolution sigma_p p
was 0.13% at 45 GeV where multiple scattering is negligible. This test beam
setup provided the possibility to study properties of lead tungstate crystals
(PbWO_4) for the BTeV experiment at Fermilab.Comment: 12 pages, 8 figures; work done by the BTeV Electromagnetic
Calorimeter grou
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