215 research outputs found
Neutrino-electron processes in a dense magnetized plasma
The neutrino-electron scattering in a dense degenerate magnetized plasma
under the conditions is investigated.
The volume density of the neutrino energy and momentum losses due to this
process are calculated. The results we have obtained demonstrate that plasma in
the presence of an external magnetic field is more transparent for neutrino
than non-magnetized plasma. It is shown that neutrino scattering under
conditions considered does not lead to the neutrino force acting on plasma.Comment: 11 pages, LATEX, to be published in Central European Science Journa
ИЗУЧЕНИЕ ВОЗМОЖНОСТИ РЕГУЛЯЦИИ АНГИОГЕНЕЗА IN VITRO С ПОМОЩЬЮ РЕКОМБИНАНТНЫХ ФРАГМЕНТОВ ИНГИБИТОРОВ АНГИОГЕНЕЗА ЭНДОСТАТИНА, ТУМСТАТИНА И PEDF
Neovascular diseases of visual organ such as age-related macular degeneration, retinopathy of prematurity, diabetic retinopathy, thrombosis of central retina vein and its branches, neovascular glaucoma, choroid and retina tumors have the leading positions in the list of ophtalmopatologies that result in blindness and incapacity. The variety of angiostatic medications of applied ophtalmology is scant. The aim of work was to study the possibile approaches to angiogenesis regulation in vitro with the help of recombinant fragments of natural inhibitors of angiogenesis such as endostatin, tumstatin and PEDF (pigment epithelial derived factor), and also their ability to be the base of potentially feasible and pharmacologically active substances. It is determined that endostatin, tumstatin and PEDF, as well as the comparison medication Bevacizumab in vitro have pro- or antiangiogenic influence. The direction of the biological effect depends on the cultivation conditions, peptide concentration in the cultural fluid and stage of angiogenesis. Неоваскулярные заболевания органа зрения, такие как возрастная макулярная дегенерация, ретинопатия недоношенных, диабетическая ретинопатия, тромбозы центральной вены сетчатки и ее ветвей, неоваскулярная глаукома, опухоли хориоидеи и сетчатки, занимают лидирующие позиции в перечне офтальмопатологии, приводящей к слепоте и инвалидизации, а также к социальной и психологической дезадаптации. Арсенал ангиостатических препаратов в практической офтальмологии скуден. Цель настоящей работы заключалась в изучении возможности регуляции ангиогенеза in vitro с помощью рекомбинантных фрагментов природных ингибиторов ангиогенеза эндостатина, тумстатина и PEDF (pigment epithelial derived factor) и применения их в качестве потенциально возможных фармакологически активных субстанций. Установлено, что in vitro эндостатин, тумстатин и PEDF, как и препарат сравнения бевацизумаб, оказывают про- или антиангиогенное действие. Направленность биологического эффекта зависит от условий культивирования, концентрации пептида в культуральной жидкости и этапа ангиогенеза.
Radio Observations of the January 20, 2005 X-Class Event
We present a multi-frequency and multi-instrument study of the 20 January
2005 event. We focus mainly on the complex radio signatures and their
association with the active phenomena taking place: flares, CMEs, particle
acceleration and magnetic restructuring. As a variety of energetic particle
accelerators and sources of radio bursts are present, in the flare-ejecta
combination, we investigate their relative importance in the progress of this
event. The dynamic spectra of {Artemis-IV-Wind/Waves-Hiras with 2000 MHz-20 kHz
frequency coverage, were used to track the evolution of the event from the low
corona to the interplanetary space; these were supplemented with SXR, HXR and
gamma-ray recordings. The observations were compared with the expected radio
signatures and energetic-particle populations envisaged by the {Standard
Flare--CME model and the reconnection outflow termination shock model. A proper
combination of these mechanisms seems to provide an adequate model for the
interpretation of the observational data.Comment: Accepted for publication in Solar Physic
Quantum and Classical Integrable Systems
The key concept discussed in these lectures is the relation between the
Hamiltonians of a quantum integrable system and the Casimir elements in the
underlying hidden symmetry algebra. (In typical applications the latter is
either the universal enveloping algebra of an affine Lie algebra, or its
q-deformation.) A similar relation also holds in the classical case. We discuss
different guises of this very important relation and its implication for the
description of the spectrum and the eigenfunctions of the quantum system.
Parallels between the classical and the quantum cases are thoroughly discussed.Comment: 59 pages, LaTeX2.09 with AMS symbols. Lectures at the CIMPA Winter
School on Nonlinear Systems, Pondicherry, January 199
Abnormal phenomena in a one-dimensional periodic structure containing left-handed materials
The explicit dispersion equation for a one-dimensional periodic structure
with alternative layers of left-handed material (LHM) and right-handed material
(RHM) is given and analyzed. Some abnormal phenomena such as spurious modes
with complex frequencies, discrete modes and photon tunnelling modes are
observed in the band structure. The existence of spurious modes with complex
frequencies is a common problem in the calculation of the band structure for
such a photonic crystal. Physical explanation and significance are given for
the discrete modes (with real values of wave number) and photon tunnelling
propagation modes (with imaginary wave numbers in a limited region).Comment: 10 pages, 4 figure
Study of the effect of neutrino oscillations on the supernova neutrino signal in the LVD detector
The LVD detector, located in the INFN Gran Sasso National Laboratory (Italy),
studies supernova neutrinos through the interactions with protons and carbon
nuclei in the liquid scintillator and interactions with the iron nuclei of the
support structure. We investigate the effect of neutrino oscillations in the
signal expected in the LVD detector. The MSW effect has been studied in detail
for neutrinos travelling through the collapsing star and the Earth. We show
that the expected number of events and their energy spectrum are sensitive to
the oscillation parameters, in particular to the mass hierarchy and the value
of , presently unknown. Finally we discuss the astrophysical
uncertainties, showing their importance and comparing it with the effect of
neutrino oscillations on the expected signal.Comment: Accepted for pubblication on Astroparticle Physics. 36 pages, 18
figure
Industrial high power electron accelerator for the energy 5-10 MeV
This paper presents the project of an industrial accelerator of the modular structure. Accelerating structure consists of the chain of coaxial ILU cavities, connected by the coupling cavities. Two designs of accelerating structure, differing by a version of coupling cavities, are presented. Main parameters of the accelerator are: energy of electrons 5-10 MeV, average beam power up to 150 kW, operating frequency 176 MHz, duty factor 10%
5 MeV 300 kW electron accelerator project
The paper presents a project of a high power linear accelerator for industrial applications. The accelerator has a modular structure and consists of the chain of accelerating cavities connected by the axis-located coupling cavities with coupling slots in the common walls. Main parameters of the accelerator are: operating frequency of 176 MHz, electron energy
ofup to 5 MeV, average beam power of300 kW. The required RF pulse power can be supplied by the TH628 diacrode.Розглянуто проект промислового електронного прискорювача великої потужності. Прискорювач має модульну
прискорюючу структуру, що складається з ланцюжка резонаторів, зв'язаних за допомогою аксиально-розміщених
резонаторів зв'язку. Зв'язок здійснюється щілинами в загальних стінках. Основні параметри прискорювача: робоча
частота 176 МГц, енергія електронів 5 МеВ, середня потужність пучка до 300 кВт. Необхідна високочастотна імпульсна потужність може бути отримана, наприклад, від діакрода TH628.Рассмотрен проект промышленного электронного ускорителя большой мощности. Ускоритель имеет модульную
ускоряющую структуру, состоящую из цепочки ускоряющих резонаторов, связанных посредством аксиально-расположенных резонаторов связи. Связь осуществляется щелями в общих стенках. Основные параметры ускорителя: рабочая
частота 176 МГц, энергия электронов 5 МэВ, средняя мощность пучка до 300 кВт. Необходимая высокочастотная импульсная мощность может быть получена, например, от диакрода TH628
Spiral anchoring in anisotropic media with multiple inhomogeneities: a dynamical system approach
Various PDE models have been suggested in order to explain and predict the
dynamics of spiral waves in excitable media. In two landmark papers, Barkley
noticed that some of the behaviour could be explained by the inherent Euclidean
symmetry of these models. LeBlanc and Wulff then introduced forced Euclidean
symmetry-breaking (FESB) to the analysis, in the form of individual
translational symmetry-breaking (TSB) perturbations and rotational
symmetry-breaking (RSB) perturbations; in either case, it is shown that spiral
anchoring is a direct consequence of the FESB.
In this article, we provide a characterization of spiral anchoring when two
perturbations, a TSB term and a RSB term, are combined, where the TSB term is
centered at the origin and the RSB term preserves rotations by multiples of
, where is an integer. When
(such as in a modified bidomain model), it is shown that spirals
anchor at the origin, but when (such as in a planar
reaction-diffusion-advection system), spirals generically anchor away from the
origin.Comment: Revised versio
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