70 research outputs found
Study of how the synthesis conditions of circular optical scales fabricated using a CLWS-300 laser image generator affect their angular errors
This paper discusses the results of a study of how the synthesis conditions of circular optical scales fabricated using a laser image generator affect their angular errors. © 2012 Optical Society of America
Dynamical principles in neuroscience
Dynamical modeling of neural systems and brain functions has a history of success over the last half century. This includes, for example, the explanation and prediction of some features of neural rhythmic behaviors. Many interesting dynamical models of learning and memory based on physiological experiments have been suggested over the last two decades. Dynamical models even of consciousness now exist. Usually these models and results are based on traditional approaches and paradigms of nonlinear dynamics including dynamical chaos. Neural systems are, however, an unusual subject for nonlinear dynamics for several reasons: (i) Even the simplest neural network, with only a few neurons and synaptic connections, has an enormous number of variables and control parameters. These make neural systems adaptive and flexible, and are critical to their biological function. (ii) In contrast to traditional physical systems described by well-known basic principles, first principles governing the dynamics of neural systems are unknown. (iii) Many different neural systems exhibit similar dynamics despite having different architectures and different levels of complexity. (iv) The network architecture and connection strengths are usually not known in detail and therefore the dynamical analysis must, in some sense, be probabilistic. (v) Since nervous systems are able to organize behavior based on sensory inputs, the dynamical modeling of these systems has to explain the transformation of temporal information into combinatorial or combinatorial-temporal codes, and vice versa, for memory and recognition. In this review these problems are discussed in the context of addressing the stimulating questions: What can neuroscience learn from nonlinear dynamics, and what can nonlinear dynamics learn from neuroscience?This work was supported by NSF Grant No. NSF/EIA-0130708, and Grant No. PHY 0414174; NIH Grant No. 1 R01 NS50945 and Grant No. NS40110; MEC BFI2003-07276, and Fundación BBVA
HS 0139+0559, HS 0229+8016, HS 0506+7725, and HS 0642+5049 : four new long-period cataclysmic variables
We present time-resolved optical spectroscopy and photometry of four relatively bright (V ∼ 14.0−15.5) long-period cataclysmic variables(CVs) discovered in the Hamburg Quasar Survey: HS 0139+0559, HS 0229+8016, HS 0506+7725, and HS 0642+5049. Their respective orbital periods, 243.69
± 0.49 min, 232.550 ± 0.049 min, 212.7 ± 0.2 min, and 225.90
± 0.23 min are determined from radial velocity and photometric variability studies. HS 0506+7725 is characterised by strong Balmer and He emission lines, short-period (∼10−20 min) flickering, and weak X-ray emission in the ROSAT All Sky Survey. The detection of a deep low state (B 18.5) identifies HS 0506+7725 as a member of the VY Scl
stars. HS 0139+0559, HS 0229+8016, and HS 0642+5049 display thick-disc like spectra and no or only weak flickering activity. HS 0139+0559 and HS 0229+8016 exhibit clean quasi-sinusoidal radial velocity variations of their emission lines but no or very little orbital photometricvariability. In contrast, we detect no radial velocity variation in HS 0642+5049 but a noticeable orbital brightness variation. We identify all three systems either as UX UMa-type novalike variables or as Z Cam-type dwarf novae. Our identification of these four new systems underlines that the currently known sample of CVs is rather incomplete even for bright objects. The four new systems add to the clustering of orbital periods in the 3−4 h range found in the sample of HQS selected CVs, and we discuss the large incidence of magnetic CVs and VY Scl/SW Sex stars found in this period range among the known population of CVs
The role of interfering RNA in immune response proliferative processes regulation in experimental model of endometrial cancer associated with thyroid disease
Оценка выраженности экспрессии маркёров пролиферации и дендритных клеток на фоне рака эндометрия при трансфекции siРНК (от англ. short interference — короткие интерферирующие молекулы рибонуклеиновой кислоты) в условиях экспериментальной патологии щитовидной железы. Было показано, что ингибирующее действие siРНК проявляется в большей степени при гипотиреоидном состоянии, указывая на важную роль гормонов щитовидной железы в регуляции экспрессии генов,
контролирующих клеточный цикл. Трансфекция siРНК приводит к повышению экспрессии зрелых дендритных клеток (СD83) в опухолевой ткани при гипотиреоидном состоянии и повышению экспрессии незрелых дендритных клеток (CD1a) при гипертиреоидном состоянии.To assess the proliferation and dendritic cells markers expression degree at short interference RNA (siRNA) transfection in endometrial cancer associated with experimental thyroid disease. siRNA inhibitory effect was more marked in animals with hypothyroidism, indicating an important role of thyroid hormones in regulating cell cycle controlling genes expression. Transfection of siRNA increased mature dendritic cells (CD83) expression in tumor tissue in animals with hypothyroidism and increased immature dendritic cells (CD1a) expression in tumor tissue in animals with hyperthyroidism
Statistical Mechanics of Canonical-Dissipative Systems and Applications to Swarm Dynamics
We develop the theory of canonical-dissipative systems, based on the
assumption that both the conservative and the dissipative elements of the
dynamics are determined by invariants of motion. In this case, known solutions
for conservative systems can be used for an extension of the dynamics, which
also includes elements such as the take-up/dissipation of energy. This way, a
rather complex dynamics can be mapped to an analytically tractable model, while
still covering important features of non-equilibrium systems. In our paper,
this approach is used to derive a rather general swarm model that considers (a)
the energetic conditions of swarming, i.e. for active motion, (b) interactions
between the particles based on global couplings. We derive analytical
expressions for the non-equilibrium velocity distribution and the mean squared
displacement of the swarm. Further, we investigate the influence of different
global couplings on the overall behavior of the swarm by means of
particle-based computer simulations and compare them with the analytical
estimations.Comment: 14 pages incl. 13 figures. v2: misprints in Eq. (40) corrected, ref.
updated. For related work see also:
http://summa.physik.hu-berlin.de/~frank/active.htm
Theory of differential inclusions and its application in mechanics
The following chapter deals with systems of differential equations with
discontinuous right-hand sides. The key question is how to define the solutions
of such systems. The most adequate approach is to treat discontinuous systems
as systems with multivalued right-hand sides (differential inclusions). In this
work three well-known definitions of solution of discontinuous system are
considered. We will demonstrate the difference between these definitions and
their application to different mechanical problems. Mathematical models of
drilling systems with discontinuous friction torque characteristics are
considered. Here, opposite to classical Coulomb symmetric friction law, the
friction torque characteristic is asymmetrical. Problem of sudden load change
is studied. Analytical methods of investigation of systems with such
asymmetrical friction based on the use of Lyapunov functions are demonstrated.
The Watt governor and Chua system are considered to show different aspects of
computer modeling of discontinuous systems
Circularly polarized electroluminescence from silicon nanostructures heavily doped with boron
The circularly polarized electroluminescence (CPEL) from silicon
nanostructures which are the p-type ultra-narrow silicon quantum well (Si-QW)
confined by {\delta}-barriers heavily doped with boron, 5 10^21 cm^-3, is under
study as a function of temperature and excitation levels. The CPEL dependences
on the forward current and temperature show the circularly polarized light
emission which appears to be caused by the exciton recombination through the
negative-U dipole boron centers at the Si-QW {\delta}-barriers interface
AE Aquarii represents a new subclass of Cataclysmic Variables
We analyze properties of the unique nova-like star AE Aquarii identified with
a close binary system containing a red dwarf and a very fast rotating
magnetized white dwarf. It cannot be assigned to any of the three commonly
adopted sub-classes of Cataclysmic Variables: Polars, Intermediate Polars, and
Accreting non-magnetized White Dwarfs. Our study has shown that the white dwarf
in AE Aqr is in the ejector state and its dipole magnetic moment is . It switched into this state due to intensive mass
exchange between the system components during a previous epoch. A high rate of
disk accretion onto the white dwarf surface resulted in temporary screening of
its magnetic field and spin-up of the white dwarf to its present spin period.
Transition of the white dwarf to the ejector state had occurred at a final
stage of the spin-up epoch as its magnetic field emerged from the accreted
plasma due to diffusion. In the frame of this scenario AE Aqr represents a
missing link in the chain of Polars evolution and the white dwarf resembles a
recycled pulsar.Comment: accepted for publication in Astronomy Reports (July 2012
Measurements of , , and spectra in Ar+Sc collisions at 13 to 150 GeV/
The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the
onset of deconfinement in strongly interacting matter through a beam energy
scan of particle production in collisions of nuclei of varied sizes. This paper
presents results on inclusive double-differential spectra, transverse momentum
and rapidity distributions and mean multiplicities of , ,
and produced in Ar+Sc collisions at beam momenta of
13, 19, 30, 40, 75 and 150 GeV/. The analysis uses the 10%
most central collisions, where the observed forward energy defines centrality.
The energy dependence of the / ratios as well as of inverse
slope parameters of the transverse mass distributions are placed in
between those found in inelastic + and central Pb+Pb collisions. The
results obtained here establish a system-size dependence of hadron production
properties that so far cannot be explained either within statistical (SMES,
HRG) or dynamical (EPOS, UrQMD, PHSD, SMASH) models
meson production in inelastic p+p interactions at 31, 40 and 80 GeV/c beam momentum measured by NA61/SHINE at the CERN SPS
Measurements of meson production via its decay mode
in inelastic interactions at incident projectile momenta of 31,
40 and 80 GeV/ ( and GeV, respectively) are
presented. The data were recorded by the NA61/SHINE spectrometer at the CERN
Super Proton Synchrotron. Double-differential distributions were obtained in
transverse momentum and rapidity. The mean multiplicities of mesons
were determined to be at
31 GeV/, at 40
GeV/ and at 80
GeV/. The results on production are compared with model
calculations (Epos1.99, SMASH 2.0 and PHSD) as well as with published data from
other experiments.Comment: arXiv admin note: substantial text overlap with arXiv:2106.0753
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