310 research outputs found
Age-related changes of the vitreous body
Innovative advances in recent years in the study of pathological changes of the posterior segment of the eye including the use of optical coherence tomography which is considered the gold standard for diagnosing vitreoretinal interface pathology, not only significantly expanded the idea of the most prevalent lesions of the structure of posterior eye segment but also discovered absolutely new aspects of their pathology. The review emphasizes the spreading understanding of vitreous body, its age-related changes in the pathology of the posterior eye segment. Two main interrelated processes occurring in the vitreous body - synchysis and syneresis, gradually increasing with age, are considered. Synchysis process begins at the early age and by the age of 70 reaches 50% of the volume of the vitreous body in 70% of the population. Parallelly, syneresis provides strength and plasticity of the entire vitreous volume due to collagen involved in formation of fibrillar frame. An important role in maintaining a stable and viscoelastic structure of the vitreous body, belonging to hyaluronic acid, is discussed, the level of which remains relatively stable at any age due to its constant synthesis. The accumulated data on the structure of age-related and pathological biodegradation of the vitreous body demonstrates inevitable progression of this process leading to age-related posterior vitreous detachment, which is a detachment of the posterior cortical layers of the vitreous body from subjacent retina. Posterior detachment under the influence of age-related changes in the vitreous body has certain stages - from incomplete juxtafoveolar detachment to complete posterior vitreous detachment with clinical retinal changes corresponding to each stage (idiopathic macular holes, lamellar macular tears, macular fibrosis, vitreomacular traction syndrome, myopic foveoschisis). Complete posterior vitreous detachment usually does not cause anatomical retinal disorders and any clinical forms of its diseases, thus, it can be considered as a natural favorable outcome
On the connection between gamma and radio radiation spectra in pulsars
The model of pulsar radio emission is discussed in which a coherent radio
emis-sion is excited in a vacuum gap above polar cap of neutron star. Pulsar X
and gamma radiation are considered as the result of low-frequency radio
emission inverse Comp-ton scattering on ultra relativistic electrons
accelerated in the gap. The influence of the pulsar magnetic field on Compton
scattering is taken into account. The relation of radio and gamma radiation
spectra has been found in the framework of the model.Comment: 15 pages, 3 figures, Russian version accepted to JETP, partly
published in JETP Letters, Vol. 85, #6 (2007
Direct SUSY dark matter detection-Theoretical rates due to the spin
The recent WMAP data have confirmed that exotic dark matter together with the
vacuum energy (cosmological constant) dominate in the flat Universe. Thus the
direct dark matter detection, consisting of detecting the recoiling nucleus, is
central to particle physics and cosmology. Supersymmetry provides a natural
dark matter candidate, the lightest supersymmetric particle (LSP). The relevant
cross sections arise out of two mechanisms: i) The coherent mode, due to the
scalar interaction and ii) The spin contribution arising from the axial
current. In this paper we will focus on the spin contribution, which is
expected to dominate for light targets.
For both modes it is possible to obtain detectable rates, but in most models
the expected rates are much lower than the present experimental goals. So one
should exploit two characteristic signatures of the reaction, namely the
modulation effect and, in directional experiments, the correlation of the event
rates with the sun's motion.
In standard non directional experiments the modulation is small, less than
two per cent. In the case of the directional event rates we like to suggest
that the experiments exploit two features, of the process, which are
essentially independent of the SUSY model employed, namely: 1) The
forward-backward asymmetry, with respect to the sun's direction of motion, is
very large and 2) The modulation is much larger, especially if the observation
is made in a plane perpendicular to the sun's velocity. In this case the
difference between maximum and minimum can be larger than 40 per cent and the
phase of the Earth at the maximum is direction dependent.Comment: 16 Latex pages, 15 figures, 3 table
Relativistic Heavy--Ion Collisions in the Dynamical String--Parton Model
We develop and extend the dynamical string parton model. This model, which is
based on the salient features of QCD, uses classical Nambu-Got\=o strings with
the endpoints identified as partons, an invariant string breaking model of the
hadronization process, and interactions described as quark-quark interactions.
In this work, the original model is extended to include a phenomenological
quantization of the mass of the strings, an analytical technique for treating
the incident nucleons as a distribution of string configurations determined by
the experimentally measured structure function, the inclusion of the gluonic
content of the nucleon through the introduction of purely gluonic strings, and
the use of a hard parton-parton interaction taken from perturbative QCD
combined with a phenomenological soft interaction. The limited number of
parameters in the model are adjusted to and -- data. Utilizing
these parameters, the first calculations of the model for -- and
-- collisions are presented and found to be in reasonable agreement with
a broad set of data.Comment: 26 pages of text with 23 Postscript figures placed in tex
HCV Infection in the Republic of Sakha (Yakutia) and Its Role of Genotypes in Clinical Outcomes of the Disease
Aim of the research. To study the epidemic manifestations of HCV infection in the Republic of Sakha (Yakutia) in order to develop recommendations for improving the effectiveness and quality of treatment and prevention measures. Materials and methods. The paper uses materials from the official statistics of the Territorial Department of Rospotrebnadzor of the Republic of Sakha (Yakutia) for 1994–2018, and data from the electronic register «Chronic viral hepatitis in the RS (Ya)» (2019). Molecular and biological studies of the genotype of the hepatitis C virus were performed jointly on the basis of the Federal state budgetary Institution «Central research Institute of epidemiology» of Rospotrebnadzor (2007–2011, n = 75). To assess the epidemiological situation, the rate of increase in morbidity is calculated on the basis of data equalized by the method of least squares. Statistical processing was performed using the SPSS 17 program. The critical significance level is assumed to be 0.05. Results. Thus, the study of long-term dynamics of the incidence of viral hepatitis shows that in the Republic of Sakha (Yakutia) a consistently high level of incidence of HCV with adverse trends in the development of the epidemic process remains. Analysis of the distribution of different variants of HCV genotypes allowed us to establish the prevalence of genotype 1b, which can determine the high frequency of cirrhosis and primary liver cancer. The current situation in the Republic regarding the incidence of viral hepatitis requires detailed monitoring, improvement of epidemiological surveillance and introduction of modern treatment methods. It is also necessary to improve the quality of health education among the population of the Republic
Optimization of neuropsychological rehabilitation of higher mental functions in junior schoolchildren with mild intellectual disability
The article studies the effectiveness of complex neuropsychological rehabilitative impact on the nonverbal and verbal higher mental functions (HMFs) in junior schoolchildren with mild intellectual disability (ID) in comparison with the impact exclusively on the verbal HMFs in the same category of children.В статье рассматривается эффективность нейропсихологического коррекционного воздействия на невербальные и вербальные высшие психические функции детей младшего школьного возраста с легкой степенью умственной отсталости
Review of scientific topics for Millimetron space observatory
This paper describes outstanding issues in astrophysics and cosmology that
can be solved by astronomical observations in a broad spectral range from far
infrared to millimeter wavelengths. The discussed problems related to the
formation of stars and planets, galaxies and the interstellar medium, studies
of black holes and the development of the cosmological model can be addressed
by the planned space observatory Millimetron (the "Spectr-M" project) equipped
with a cooled 10-m mirror. Millimetron can operate both as a single-dish
telescope and as a part of a space-ground interferometer with very long
baseline.Comment: The translation of the original article in Physics Uspekhi
http://ufn.ru/ru/articles/2014/12/c
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