Effect of plasma resonances on dynamic characteristics of double graphene-layer optical modulator

We analyze the dynamic operation of an optical modulator based on double graphene-layer(GL) structure utilizing the variation of the GL absorption due to the electrically controlled Pauli blocking effect. The developed device model yields the dependences of the modulation depth on the control voltage and the modulation frequency. The excitation of plasma oscillations in double-GL structure can result in the resonant increase of the modulation depth, when the modulation frequency approaches the plasma frequency, which corresponds to the terahertz frequency for the typical parameter values.Comment: 8 pages, 4 figure

Expression of Tumor Assosiated and Epithelial-mesenchymal Transition Markers in 2d and 3d Cell Cultures of Mcf-7

The target effects on the expression of epithelial-mesenchymal transition regulation molecules are promising for cancer therapy, including breast cancer. 3D cell culture is a model for studying epithelial-mesenchymal transition in vitro and may become a test system for anticancer therapy.Aim of research. The aim of this research was to evaluate and compare the expression of tumor associated and epithelial-mesenchymal transition markers in tumor cells of breast adenocarcinoma (MCF-7 cell line) in 2D and 3D cell culture.Methods. For realization of the aim MCF-7 cell line (breast adenocarcinoma) was chosen as an experimental model in vitro. The monolayer cell culture was cultured in standard conditions (37 0C, 5 % CO2, humidity 95 %). The initial density of inoculated cells was 2 x 104 cells/cm2. The cells were incubated for two days before their use in the experiment. For the initial generation of spheroids the monolayer cell culture was removed off the substrate after the four days of incubation, using 0,25 % Trypsin-EDTA, and placed in nutrient medium with 5 % carboxymethyl cellulose (Bio-Rad, USA) at concentration of 5 x 105 cells/ml. Then the plates were incubated on an orbital shaker (Orbital shaker, PSU-10i, Biosan, Latvia) at 50 rpm for 3–5 hours. Half of culture medium was replenished every 3 days. A spheroid culture was maintained for 14 days. Detection of markers (ER, p53, EpCAM, vim, AE1/AE3, panCK, EGFR) in 2D and 3D cell culture was performed using immunohistochemistry method with primary monoclonal antibodies. Histological samples of cells were photographed to compare the morphological characteristics and the expression of proteins in monolayer and spheroid cultureResults. The results demonstrated that the percentage of tumor marker positive cells (ER+, EGFR+, EpCAM+, panCK+, AE1/AE3+) in monolayer culture is 1.25–2 times than more in spheroid culture. In contrast, tumor spheroids consist of fewer cells with the expression of epithelial markers such as EpCAM and AE1/AE3, but they contain a large number of cells that expressed mesenchymal marker vimentin by 5 % and p53 by 10 %. This may indicate that the cells acquire a mesenchymal phenotype. However, tumor cells of monolayer cell culture were not expressed vimentin.Conclusions. Our results demonstrated the differences of expression of tumor associated and epithelial-mesenchymal transition markers in 2D and 3D breast cancer cell cultures. Thus, the percentage of epithelial markers (Cytokeratines and epithelial cell adhesion molecule) in tumor spheroids is less than in cells of monolayer however spheroids cells begin expressing a mesenchymal marker – vimentin. In 3D cell culture only the outer cell layers expressed tumor associated proteins unlike 2D cell culture in which all of cells showed equally expression. Reduced of manifestation of tumor associated markers in 3D cell culture may indicate an increase of stem properties. These data showed that 3D cell culture more than 2D cell culture characterized processes of epithelial-mesenchymal transition

Low temperature scattering with the R-matrix method: the Morse potential

Experiments are starting to probe collisions and chemical reactions between atoms and molecules at ultra-low temperatures. We have developed a new theoretical procedure for studying these collisions using the R-matrix method. Here this method is tested for the atom -- atom collisions described by a Morse potential. Analytic solutions for continuum states of the Morse potential are derived and compared with numerical results computed using an R-matrix method where the inner region wavefunctions are obtained using a standard nuclear motion algorithm. Results are given for eigenphases and scattering lengths. Excellent agreement is obtained in all cases. Progress in developing a general procedure for treating ultra-low energy reactive and non-reactive collisions is discussed.Comment: 18 pages, 6 figures, 3 tables, conferenc

Critical vortex line length near a zigzag of pinning centers

A vortex line passes through as many pinning centers as possible on its way from one extremety of the superconductor to the other at the expense of increasing its self-energy. In the framework of the Ginzburg-Landau theory we study the relative growth in length, with respect to the straight line, of a vortex near a zigzag of defects. The defects are insulating pinning spheres that form a three-dimensional cubic array embedded in the superconductor. We determine the depinning transition beyond which the vortex line no longer follows the critical zigzag path of defects.Comment: 8 pages, 25 figures with low resolution option, 1 table. To be published in Eur. Phys. Jour.

Practical thermodynamics of Yukawa systems at strong coupling

Simple practical approach to estimate thermodynamic properties of strongly coupled Yukawa systems, in both fluid and solid phases, is presented. The accuracy of the approach is tested by extensive comparison with direct computer simulation results (for fluids and solids) and the recently proposed shortest-graph method (for solids). Possible applications to other systems of softly repulsive particles are briefly discussed.Comment: Published in J. Chem. Phy

Detection of an atmosphere around the super-Earth 55 Cancri e

We report the analysis of two new spectroscopic observations of the super-Earth 55 Cancri e, in the near infrared, obtained with the WFC3 camera onboard the HST. 55 Cancri e orbits so close to its parent star, that temperatures much higher than 2000 K are expected on its surface. Given the brightness of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length and a very high scanning speed. We use our specialized pipeline to take into account systematics introduced by these observational parameters when coupled with the geometrical distortions of the instrument. We measure the transit depth per wavelength channel with an average relative uncertainty of 22 ppm per visit and find modulations that depart from a straight line model with a 6$\sigma$ confidence level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably hydrogen-rich. Our fully Bayesian spectral retrieval code, T-REx, has identified HCN to be the most likely molecular candidate able to explain the features at 1.42 and 1.54 $\mu$m. While additional spectroscopic observations in a broader wavelength range in the infrared will be needed to confirm the HCN detection, we discuss here the implications of such result. Our chemical model, developed with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic than previously thought.Comment: 10 pages, 10 figures, 4 tables, Accepted for publication in Ap

Етнонаціональна політика як фактор державотворення в Україні

Юрченко М. М. Етнонаціональна політика як фактор державотворення в Україні : автореф. дис. ... канд. політ. наук : 23.00.02 / М. М. Юрченко; кер. роботи Д. С. Шелест; Нац. ун.-т "Одеська юридична академія". – Одеса, 1998. – 18 с.Дисертація на здобуття наукового ступеня кандидата політичних наук за спеціальністю 23.00.02 – політичні інститути та процеси. – Одеська державна юридична академія, Одеса, 1998. Дисертаційна робота виконана в руслі нового напрямку політичної науки - етнодержавознавства. На основі різноманітних джерел проаналізована сутність та значення етнонаціонального фактора в суспільному житті Півдня України, проблеми української національної ідеї та інтересу, етнополітичний потенціал українського державотворення з врахуванням регіональних особливостей, аспекти проблем суверенітету. У дослідженні наголошується увага на методології аналізу основного змісту концепції етнополітики держави та діяльності місцевих органів влади. Внесені пропозиції і рекомендації щодо політико-правового забезпечення життєдіяльності української нації, корінних народів, етнічних меншин в українському соціумі, функціонуванні державного механізму в сфері міжетнічних відносин.Диссертация на соискание ученой степени кандидата политических наук по специальности 23.00.02 – политические институты и процессы. – Одесская государственная юридическая академия, Одесса, 1998. Диссертационная работа выполнена в русле нового направления политической науки - этногосударствоведения. На базе различных источников проанализирована сущность и значение этнонационального фактора в общественной жизни Юга Украины, проблемы украинской национальной идеи и интересов, этнополитический потенциал украинского государства с учетом региональных особенностей, аспекты проблем суверенитета. В исследовании акцентируется внимание на методологии анализа главного содержания концепции этнополитики государства и деятельность местных органов власти. Внесены предложения и рекомендации относительно политико-правового обеспечения жизнедеятельности украинской нации, коренных народов, этнических меньшинств в украинском социуме, функционировании государственного механизма в сфере межэтнических отношений.Thesis searching for a scientific degree of candidate of political science on speciality 23. 00. 02 – political institutes and processes. – Odessa State Law Academy, Odessa, 1998. Thesis is done in the spirit of new direction of political science – ethnostatecreation. The essence and importance of ethnonational factor in the social life of South Ukraine problem of Ukrainian national idea and interests ethnopolitical potential of Ukrainian state, taking into consideration regional peculiarities and aspects of sovereignty problems were analyzed on the base of different sources. In the thesis attention is given to methods of analyses of the main essence of conception the state and local power bodies ethnopolitics. The proposals and recommendations, concerning political and law guarantees of Ukrainian nation life, native people, ethnical minorities in Ukrainian society, functioning of state mechanism in the sphere of ethnical relations were submitted

Flux Penetration in Superconducting Strip with Edge-Indentation

The flux penetration near a semicircular indentation at the edge of a thin superconducting strip placed in a transverse magnetic field is investigated. The flux front distortion due to the indentation is calculated numerically by solving the Maxwell equations with a highly nonlinear $E(j)$ law. We find that the excess penetration, $\Delta$, can be significantly ($\sim$ 50%) larger than the indentation radius $r_0$, in contrast to a bulk supercondutor in the critical state where $\Delta=r_0$. It is also shown that the flux creep tends to smoothen the flux front, i.e. reduce $\Delta$. The results are in very good agreement with magneto-optical studies of flux penetration into an YBa$_2$Cu$_3$O$_x$ film having an edge defect.Comment: 5 pages, 7 figure