The Theory of Three-level Photon Echo Using of Rotating Wave Approximation

The three level photon echo has been described in different works by using rotating wave approximation but none of them did not get results which show the effects of field's frequencies on frequency of ground level of system. In this work, we studied a Lambda type system theoretically and numerically. By considering the Doppler effect in environment, we get different equation for polarization of echo signal and its intensity

Strong out-of-plane magnetic anisotropy of Fe adatoms on Bi2_2Te3_3

The electronic and magnetic properties of individual Fe atoms adsorbed on the surface of the topological insulator Bi$_2$Te$_3$(111) are investigated. Scanning tunneling microscopy and spectroscopy prove the existence of two distinct types of Fe species, while our first-principles calculations assign them to Fe adatoms in the hcp and fcc hollow sites. The combination of x-ray magnetic circular dichroism measurements and angular dependent magnetization curves reveals out-of-plane anisotropies for both species with anisotropy constants of $K_{\text{fcc}} = (10 \pm 4)$ meV/atom and $K_{\text{hcp}} = (8 \pm 4)$ meV/atom. These values are well in line with the results of calculations.Comment: 6 pages, 3 figure

Nonlinear Doppler - Free comb-spectroscopy in counter-propagating fields

The method of Doppler - free comb - spectroscopy for dipole transitions was proposed. The calculations for susceptibility spectrum for moving two-level atoms driving by strong counter propagating combs have been done. The used theoretical method based on the Fourier expansion of the components of density matrix on two rows on kv (v-velocity of group of atoms, k-projection of wave vector) and {\Omega} (frequency between comb components). For testing of validity of this method the direct numerical integration was done. The narrow peaks with homogeneous width arise on the background of Doppler counter. The contrast of these peaks is large for largest amplitudes of comb-components. Power broadening is increasing with increase of field amplitudes. The spectral range of absorption spectrum is determined by the spectral range of comb generator and all homogeneous lines arise simultaneously. The spectral resolution is determined by the width of homogeneously-broadening lines. The physical nature of narrow peaks is in the existence of multi-photon transitions between manifolds of quasi-energy levels arising for different groups of atoms moving with velocities that satisfy to the resonant conditions 2kv= (n+l){\Omega}, where n, l - are integers and {\Omega} - frequency difference between comb teeth

Identifizierung und Charakterisierung der biologischen Funktion von PolySia-NCAM in humanem Lungengewebe

Bei Polysialinsäure (PolySia) handelt es sich um ein Homopolymer aus alpha 2,8-verknüpften N-Acetylneuraminsäuren, welches überwiegend als posttranslationale Modifikation des neuralen Zelladhäsionsmoleküls NCAM in Säugetieren vorliegt. Durch die hohe Anzahl an negativ geladenen Carboxylgruppen erschwert PolySia die Zelladhäsion und spielt damit eine entscheidende Rolle bei der Regulation von Zellkontakten und Migrationsprozessen. Die große Bedeutung von PolySia wird im Zuge eines knock out-Modells deutlich, in dem die Abwesenheit des Moleküls zu einem letalen Phänotyp in der Maus führte. Während die funktionelle Relevanz von PolySia im Nervensystem bereits vielfach untersucht wurde, ist deren Rolle in anderen Organsystemen noch weitgehend ungeklärt. In der vorliegenden Arbeit wurde PolySia-NCAM in der humanen, adulten Lunge vorwiegend auf bronchialen Epithelzellen detektiert. Unter Zuhilfenahme eines Zellkulturmodells konnte weiterhin gezeigt werden, dass Interleukin-1beta (IL-1beta) oder Lipopolysaccharid (LPS) von gram-negativen Bakterien zu einem ectodomain shedding des Glykoproteins führen, was wiederum die Freisetzung von löslichem PolySia-NCAM-110 induziert. Darüber hinaus konnten auch in Lungengewebe von Patienten, die an der chronisch-inflammatorischen Lungenkrankheit COPD (chronic obstructive pulmonary disease) litten, welche mit einem erhöhten IL-1beta-Spiegel einhergeht, gesteigerte Mengen an löslichem PolySia-NCAM-110 detektiert werden. Letzteres konnte auch in entzündlichem Gewebe Bleomycin-behandelter Mäuse nachgewiesen werden, nicht jedoch in der fibrosierenden, nicht-entzündlichen Lungenerkrankung IPF (Idiopathisch pulmonale Fibrose). Zusätzlich wurde gezeigt, dass lösliches PolySia-NCAM-110 direkt mit extrazellulären Histonen sowie dem von neutrophilen Granulozyten produzierten NET (neutrophil extracellular traps) in Wechselwirkung tritt und somit in der Lage ist, deren Zytotoxizität für körpereigene Zellen abzumildern. Ausgehend von diesen Daten kann postuliert werden, dass lösliches PolySia-NCAM-110, welches im Zuge einer inflammatorischen Immunantwort des Lungengewebes durch ectodomain-shedding freigesetzt wird, eine Rolle als immunmodulatorisches Agens im Kontext der angeborenen Immunität der Lunge spielen könnte.Polysialic acid (polySia), a homopolymer consisting of alpha 2,8-linked N-acetyl neuraminic acid residues, is mainly present as a posttranslational modification of the neural cell adhesion molecule (NCAM) in mammals. Due to its high number of negatively charged carboxyl groups polySia counteracts cell adhesion and plays therefore a crucial role in the regulation of cell contact/repulsion as well as migration processes. The importance of polySia becomes apparent using a knock out model, where the absence of polySia results in a lethal phenotype in mice. While the functional impact of polySia in the neuronal system has been considerably studied, the biological relevance of polysialylation in other organ systems is less established. Within this doctoral thesis polySia-NCAM was prevalently detected on bronchial epithelial cells the in adult, human lung. Using a cell culture model, it could be further shown, that interleukin-1beta (IL-1beta) or lipopolysaccharide (LPS) from gram-negative bacteria induced an ectodomain shedding of the glycoprotein, resulting in a release of soluble polySia-NCAM-110. Moreover this soluble form could be similarly detected in lung tissue of patients suffering from COPD (chronic obstructive pulmonary disease), which comes along with high-levels of IL-1beta. PolySia-NCAM-110 is also present in inflammable tissue of bleomycin-treated mice, but not in fibrotic tissue from patients with IPF (idiopathic pulmonary fibrosis). Intriguingly, polySia-NCAM interacts with extracellular histones as well as NET (neutrophil extracellular traps) generated by neutrophil granulocytes, thus decreasing their cytotoxic effects on endogenous epithelial cells. Based on these observations it can be assumed that soluble polySia-NCAM-110, which is released by ectodomain-shedding during an inflammatory response of lung tissue, may represent a novel player within the scenario of the innate immunity of the lung

Microwave-induced spin-flip scattering of electrons in point contacts

We investigate resonant interaction of conduction electrons with an electromagnetic field that irradiates a point contact between a ferromagnetic and a normal metal in the presence of a strong magnetic field of order 1 T. We show that electron spin-flips caused by resonant absorption and stimulated emission of photons result in a sharp peak in the magnetic-field dependence of the point-contact resistance. The height of the peak is shown to be directly proportional to the net rate of energy transfer to the electromagnetic field in the point contact due to absorption and stimulated emission of photons. Estimations indicate that our theory can serve as a basis for the explanation of recent experiments [A.M. Kadigrobov et al., New J. Phys. 13, 023007 (2011)]

THE ACTIVITIES OF UGTU BUSINESS INCUBATOR IN SHAPING THE IMAGE OF THE UNIVERSITY

The article highlights the activity of business-incubator UGTU in the context of forming the image of the university. The potential for optimization of university's image elements through the communication work with various target audiences of the university is covered. The article describes the university "s image elements such as the image of educational services, students' image, internal image of the organization, university rector "s image, the image of teaching staff and personnel, the social image of the organization, the visual image of the organization, business organization"s image through the prism of education and information activities of the business incubator. The purpose of the article is to reveal the role of such a university structure in maintaining its positive image

PROPERTIES OF THE MAXIMUM LIKELIHOOD ESTIMATES OF THE EXPONENT OF PARETO DISTRIBUTION

This paper investigates the statistical properties of maximum likelihood estimation index of the Pareto distribution. In recent years, power distribution laws such as Pareto distribution attract the attention of researchers in various fields of science and technology, from economics and linguistics to Internet traffic analysis. Therefore, the problem of determining the exponent of the power law for a given sample is of exceptional practical importance. It is analytically proved that this estimate is biased, although valid. A formula that eliminates the bias is proposed. Besides, a formula for the variance of the unbiased estimate is analytically derived. In addition, the problem of finding the distribution function and probability density of this estimate as a random variable is set and analytically solved. Next, a formula for mathematical expectation and dispersion based on previously determined probability density is found. The obtained results can be used in various fields of human activity, for example, to predict the intensity of natural and man-made disasters