506 research outputs found
Dynamics of Vortex Pair in Radial Flow
The problem of vortex pair motion in two-dimensional plane radial flow is
solved. Under certain conditions for flow parameters, the vortex pair can
reverse its motion within a bounded region. The vortex-pair translational
velocity decreases or increases after passing through the source/sink region,
depending on whether the flow is diverging or converging, respectively. The
rotational motion of two corotating vortexes in a quiescent environment
transforms into motion along a logarithmic spiral in the presence of radial
flow. The problem may have applications in astrophysics and geophysics.Comment: 13 pages, 9 figure
Correlation analysis between journal metrics and subscription price for selected journals
The given article gives an account on the correlation analysis between the journal metrics (SNIP, SJR, IF) and the subscription price for two groups of journals (114 Economics journals and 150 Mathematics and Computer Science journals) which were presented on Elsevier website in October 201
Cross correlation analysis between SNIP, SJR and if for selected journals
The cross correlation analysis was presented in the given article and linear regression equations between various types of journal metrics (SNIP, SJR, IF) were obtained for economics and mathematics and computer science journal
Conceptualization of the experience of the individual in the educational space in the light of scientific rationality as a problem of professional identity in global and sociocultural dynamics
As a problem, professional identity associated with the educational space is investigated from the position of belonging to professional groups. The contradictory state of education in the modern world actualizes the problem of identity in the educational space from the perspective of classical modern European rationality with its focus on the scientific forms of cognition, knowledge. The current situation in the world educational space is developed in the ambiguity of the idea of the world, which is expressed in the crisis of universalism and cognitive integrity: the place of rational knowledge in culture is replaced by mythic ideas. The way of thinking exists independently of the individual. The transfer of thinking is a learning task. However, at the present stage, with a sharp increase in the amount of information reported, the emphasis is on formalizing of the educational process, rather than constructivizing. The teacher’s responsibility as a carrier of scientific rationality, which primarily defines the universal meaning of human activity in the transmission of social experience and knowledge, is growing. The level of education of a person is a measure of implementation of the possibility of his/her formation, taking into account the dichotomous nature of the individual's socialization and professional identity based on it. Such a holistic perception of the world will allow gaining a deep understanding of the essence of things, fitting science into the cultural context of modernity
Raman scattering in a two-dimensional electron gas: Boltzmann equation approach
The inelastic light scattering in a 2-d electron gas is studied theoretically
using the Boltzmann equation techniques. Electron-hole excitations produce the
Raman spectrum essentially different from the one predicted for the 3-d case.
In the clean limit it has the form of a strong non-symmetric resonance due to
the square root singularity at the electron-hole frequency while
in the opposite dirty limit the usual Lorentzian shape of the cross section is
reestablished. The effects of electromagnetic field are considered
self-consistently and the contribution from collective plasmon modes is found.
It is shown that unlike 3-d metals where plasmon excitations are unobservable
(because of very large required transfered frequencies), the two-dimensional
electron system gives rise to a low-frequency ()
plasmon peak. A measurement of the width of this peak can provide data on the
magnitude of the electron scattering rate.Comment: 4 pages, 3 figures. to appear in Phys. Rev. B 59 (1999
Structure of MnO nanoparticles embedded into channel-type matrices
X-ray diffraction experiments were performed on MnO confined in mesoporous
silica SBA-15 and MCM-41 matrices with different channel diameters. The
measured patterns were analyzed by profile analysis and compared to numerical
simulations of the diffraction from confined nanoparticles. From the lineshape
and the specific shift of the diffraction reflections it was shown that the
embedded objects form ribbon-like structures in the SBA-15 matrices with
channels diameters of 47-87 {\AA}, and nanowire-like structures in the MCM-41
matrices with channels diameters of 24-35 {\AA}. In the latter case the
confined nanoparticles appear to be narrower than the channel diameters. The
physical reasons for the two different shapes of the confined nanoparticles are
discussed.Comment: 8 pages, including 9 postscript figures, uses revtex4.cl
Red flags to diagnose infiltrative cardiomyopathies
Infiltrative cardiomyopathies are a group of diseases characterized by the deposition of abnormal substances in heart tissues, which leads to thickening of the walls or dilation of chambers with a secondary decrease in wall thickness and the development of diastolic, less often systolic, ventricular dysfunction. Most often, these are progressive diseases that, in the absence of adequate therapy, have an unfavorable prognosis. Clinical manifestations of infiltrative cardiac diseases are variable, which often leads to diagnostic difficulties and errors. In most cases, specific laboratory and morphological tests are required to confirm or clarify the diagnosis. Early diagnosis is critical to initiating therapy and improving patient prognosis. This article provides characteristic signs and symptoms, the so-called "red flags", making it possible to suspect infiltrative cardiomyopathies, diagnose them at an early stage and start life-saving therapy
Egg retention and dispersal activity in the parasitoid wasp, Trichogramma principium
Effects of egg retention on movement and dispersal activity of Trichogramma principium (Hymenoptera, Trichogrammatidae) females were investigated under laboratory conditions. Individual females were observed during one minute in the absence of hosts. Movement activity and dispersal rate were estimated by the length of the track and by the distance from the start point, respectively. Before the test, all wasps during 2 – 4 days were presented with a possibility to parasitize a factitious laboratory host, Sitotroga cerealella Oliv. (Lepidoptera, Gelechiidae). Wasps that had parasitized before the test show significant reduction of spontaneous walking activity and dispersal rate when compared with females that refused to parasitize the non-preferred host (i.e. manifested egg retention). This effect cannot be considered as a direct arrestment reaction to the host because during the test period, no hosts were provided. Thus, egg retention results not only in temporal spread, but also in more intensive spatial dispersal of a group of simultaneously emerged females
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