Modeling of surface-induced second-harmonic generation from multilayer structures by the transfer matrix method.

We analytically and numerically investigate surface second-harmonic generation (SHG) from a stack of dielectric layers. We develop a theoretical formalism based on the transfer matrix method for the calculation of the surface-driven second-harmonic radiation from multilayer structures and elaborate it for the case of ultrathin dielectric layers using a power series expansion to derive the effective surface nonlinear tensor for the whole stack. We show that for deeply subwavelength thicknesses of the layers the surface responses from all interfaces can efficiently sum up, leading to largely enhanced efficiency of SHG. As a result, such surface-driven nonlinearity can become comparable to the bulk nonlinearity in noncentrosymmetric semiconductors and can yield high performance for nonlinear nanophotonic applications.

Far-field polarization signatures of surface optical nonlinearity in noncentrosymmetric semiconductors.

We analyse possibilities to quantitatively evaluate the surface second-order optical nonlinearity in noncentrosymmetric materials based on polarization-resolved analysis of far-field radiation patterns of second-harmonic generation. We analytically demonstrate that for plane-wave illumination the contribution to the second-harmonic signal from the surface of a nonlinear medium exhibits different polarization properties and angular dependencies compared to the contribution from the bulk. In view of this, we optimize the illumination geometry in order to enable the most efficient separation and comparison of both nonlinearities. Furthermore, we consider the illumination of an AlGaAs slab by a tightly-focused linearly-polarized Gaussian beam as an alternative measurement geometry. It is found that the reliable separation of the surface nonlinearity contribution as well as a wide range of detectable values can be achieved with this geometry as well.

Unusual terahertz waveforms from a resonant medium controlled by diffractive optical elements.

Up to now, full tunability of waveforms was possible only in electronics, up to radio-frequencies. Here we propose a new concept of producing few-cycle terahertz (THz) pulses with widely tunable waveforms. It is based on control of the phase delay between different parts of the THz wavefront using linear diffractive optical elements. Suitable subcycle THz wavefronts can be generated via coherent excitation of nonlinear low-frequency oscillators by few-cycle optical pulses. Using this approach it is possible to shape the electric field rather than the slow pulse envelope, obtaining, for instance, rectangular or triangular waveforms in the THz range. The method is upscalable to the optical range if the attosecond pump pulses are used.

Unipolar subcycle pulse-driven nonresonant excitation of quantum systems.

The interaction of subcycle pulses with quantum systems is considered when the pulse duration becomes much smaller than the timescales of electron oscillations. We show analytically that the interaction process in this case is governed by the electric pulse area. The efficient nonresonant excitation of quantum systems by subcycle pulses with a high degree of unipolarity is demonstrated. The results are confirmed by direct numerical solution of multilevel Bloch equations.

Population density gratings induced by few-cycle optical pulses in a resonant medium.

Creation, erasing and ultrafast control of population density gratings using few-cycle optical pulses coherently interacting with resonant medium is discussed. In contrast to the commonly used schemes, here the pulses do not need to overlap in the medium, interaction between the pulses is mediated by excitation of polarization waves. We investigate the details of the dynamics arising in such ultrashort pulse scheme and develop an analytical theory demonstrating the importance of the phase memory effects in the dynamics.

Generation of unipolar half-cycle pulses via unusual reflection of a single-cycle pulse from an optically thin metallic or dielectric layer.

We propose a strikingly simple method to form approximately unipolar half-cycle optical pulses via reflection of a single-cycle optical pulse from a thin flat metallic or dielectric layer. Unipolar pulses in reflection arise due to specifics of one-dimensional pulse propagation. Namely, we show that the field emitted by the layer is proportional to the velocity of the oscillating charges in the medium, instead of their acceleration. Besides, the oscillation velocity of the charges can be forced to keep a constant sign throughout the pulse duration. That is, reflection of ultrashort pulses from broad-area layers with nanometer-scale thickness can be very different from the common reflection in the case of longer pulses and thicker layers. This suggests a possibility of unusual transformations of few-cycle light pulses in completely linear optical systems.

[Pulmonary Hypertension in Takayasu Arteritis].

Takayasu arteritis is well-known rare form of large vessel vasculitis. Pulmonary involvement is observed in 50% of cases. However, pulmonary hypertension is a rare complication of pulmonary artery stenosis. In this article we present a rare clinical case of Takayasus arteritis with typical stenosis of subclavian, carotid arteries, and involvement of pulmonary arteries with development of severe pulmonary hypertension. The article also contains discussion of current methods of diagnosis and treatment of pulmonary artery stenosis in Takayasus arteritis with special focus on effectiveness and complications of angioplasty and surgery.

[Intravital and postmortem morphological studies and magnetic resonance imaging of arrhythmogenic right ventricular dysplasia].

The authors conducted histological, immunohistochemical, and morphometric studies of 47 endomyocardial biopsies and 33 hearts with a high morphological criterion for the diagnosis of arrhythmogenic right ventricular dysplasia after F.I. Marcus et al. (2010), as well as intravital and postmortem cardiac magnetic resonance imaging (MRI). The average residual cardiomyocyte area was 39.7 +/- 12.8%, and the average cardiomyocyte diameter was 10.4 +/- 1.5 microm. Muscle fiber atrophy, lipomatosis, and fibrosis in the right ventricle were detected in all cases, myocarditis in 44%, mitral valve prolapse in 42%, and muscle fiber dyscomplexation in the right ventricular in 33%. The most informative signs for the diagnosis of arrhythmogenic right ventricular dysplasia using MRI are right ventricular contraction dyssynchrony and those using a morphological study are a residual cardiomyocyte area and muscle fiber atrophy in the right ventricle. A decrease in or focal absence of gamma-catenin expression in the muscle fibers was observed only in 60% of the patients.

Development of a cryopreservation protocol for testicular interstitial cells with the account of temperature intervals for controlled cooling below -60°Ð¡.

A long course of anticancer therapy may lead to testicular steroidogenesis destruction. Cryopreservation of testicular interstitial cells (TIC) would be a strategy to protect hormonal and fertile potential of pre-pubertal boys treated with chemo - or radiotherapy. The aim of this research was to optimize protocols for freezing of TIC. Essential physical processes associated with the presence of dimethyl sulphoxide (Me(2)SO) in the cryoprotectant solution take place at the temperatures below -60°Ð¡. These processes are the eutectic crystallization at the stage of freezing and the recrystallization before the melting of the eutectic mixture at the stage of heating. Both of the processes affect the viability of the cells subjected to cryopreservation. Temperature intervals when these processes take place were determined by the method of thermoplastic deformation for 10% Me(2)SO selected for cryopreservation of TIC. Rat TIC were cryopreserved using five different protocols which varied in cooling rates within the chosen temperature intervals. Post-thaw cell viability and metabolic activity were evaluated by Trypan Blue and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) staining assays. Leydig cell recovery after cryopreservation was measured by 3-beta-hydroxysteroid dehydrogenase reaction. Based on the obtained results, the authors developed a cryopreservation protocol for TIC which makes it possible to achieve great cell viability due to using controlled cooling rates within the temperature intervals below -60°Ð¡.

[Biolictic transformation of soybean by new selective marker gene resistant to dinitroanilines].

Biolistic transformation of soybean by construction carrying a mutant alpha-tubulin gene as selective marker gene conferring resistance to dinitroaniline herbicides, and by additional construction pAHTUBI carrying a full-length barley beta-tubulin gene for correct co-expression of exogeneous tubulin in cells of transgenic soybean lines has been realized. It was established that 10 microM trifluralin is the most optimal selective concentration to pick up transformed soybean lines. Transgenic nature of offained regenerants was confirmed by Southern blotting hybridization using specific probe to selective alpha-tubulin gene.

[Comparative analysis of embryogenic potential of soybean cultivars zoned in different eco-geographic world regions].

Embryogenic potential of 19 soybean cultivars originated from different eco-geographic regions (Europe, China, America and Far East) has been established and analyzed. Cultivars TSZ-14, Amurskaja-111, Gribovskaja mestnaja were emphasized as highly embryogenic genotypes. Cultivar Mantherova biela vel. revealed the highest embryogenic potential (80%). The comparison of embryogenic potential of the Ukrainian cultivars with given data indicated various parameters which could affect the induction of soybean somatic embryogenesis. It had also been supposed that cultivars from the Far East and Europe could have the potential for further screening of new highly embryogenic genotypes. The data obtained enlarge the data base pool of the soybean somatic embryogenesis research and enable using the most appropriate cultivars for further genetic improvement.

[Evaluation of embryological potential of soybean cultivars zoned in forest, steppe, and marshy woodlands of Ukraine as essential stage for the further transformation]. / Otsenka émbriogennogo potentsiala sortov soi, raionirovannykh v zone Ukrainskikh lesostepi i poles'ia kak neobkhodimyi étap dlia ikh dal'neishei transformatsii.

Seven soybean (Glycine max (L.) Merr.) cultivars zoned in forest-steppe and marshy woodlands of Ukraine: "Chernuatka", "Vasylkivska", "Kyivska-91", "Kyivska-27", "Marjana", "Chernobura" and "Altair" were established in vitro for somatic embryogenesis inducing. Cultivars "Marjana" (88%) and "Vasylkivska" (86%) demonstrated the highest embryogenic capacity among all the tested cultivars. During the further plant regeneration cultivars "Marjana" and "Kyivska-91" showed the best capacity to form adult plants despite the fact that embryogenic capability of the cultivar "Kyivska-91" was 71%. According to the obtained data three genotypes were selected for the further investigation of effective methods of biolictic transformation of ukrainian cultivars.