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.

[Selection of antiplatelet therapy for patients with stable angina].

Acetylsalicylic acid (ASA) has a 120­years long history. First ASA was used as an antipyretic and anesthetic medicine, nowadays it is widely prescribed to patients with coronary arteries disease as antithrombotic cure for prevention of major adverse clinical events (MACE). Though there are a lot of trials about usage of ASA for first and secondary MACE prevention still there are unmet clinical needs - dosage choice, the therapy length, diagnostic and management of ASA resistance, and also the prophylaxis of gastro-enteric hemorrhages.

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.

Ultrafast creation and control of population density gratings via ultraslow polarization waves.

In the regime of resonant coherent light-matter interaction, light pulses may interact with each other indirectly via a polarization wave created by the other pulse. We show that such interaction allows fast creation and erasing of high-contrast dynamic population density gratings, as well as control of their period in a few-cycle regime. Our scheme uses counter-propagating optical pulses, which do not cross each other in the medium. The mechanism is able to work with pulse durations up to the single-cycle limit. Somewhat surprisingly, ultrafast grating wave vector control requires the generation of polarization waves with the phase velocity much smaller than that of light.

Self-induced transparency mode locking, and area theorem.

Self-induced transparency mode locking (or coherent mode locking, CML), which is based on intracavity self-induced transparency soliton dynamics, potentially allows achievement of nearly single-cycle intracavity pulse durations, much below the phase relaxation time T2 in a laser which, despite having great promise, has not yet been realized experimentally. We develop a diagram technique which allows us to predict the main features of CML regimes in a generic two-section laser far from the single-cycle limit. We show that CML can arise directly at the first laser threshold if the phase relaxation time is large enough. Furthermore, we discuss the stability of the corresponding mapping. We also predict the existence of "super-CML regimes," with a pulse coupled to several Rabi oscillations in the nonlinear medium.

[The safety of robotics for restorative medicine].

The present article is devoted to the peculiarities of the safety measures that need to be taken during the operation of the automated robots intended to perform noninvasive controlled deformations of the patient's soft tissues. The authors propose the use of the commercially available devices for nonmedical applications operated without enclosure for staff as basic robots.

[The role of gastroduodenal diseases in the development of cardiac arrhythmia of the sick sinus syndrome type]. / Rol' gastroduodenal'nykh zabolevanii v razvitii serdechnykh aritmii kharaktera sindroma podavlennogo sinusovogo uzla.

A total of 105 patients with suspected sick sinus syndrome were examined. All of them underwent transesophageal pacing and endoscopical investigation. A relationship is shown between lesions of the gastrointestinal tract and emergence of the sinus vagal depression leading to various disturbances of cardiac rhythm.

[Anti-arrhythmic activity of atropine, ritmilen, obsidan and cordarone in patients with ventricular allorhythmia]. / Antiaritmicheskaia aktivnos't atropina, ritmilena, obzidana i kordarona u bo'lnykh s zheludochkovymi alloritmiiami.

Comparative study of the anti-arrhythmic activity of ritmilen, obsidan, cordarone++ and atropine was conducted in 140 patients with ventricular allorhythmia. Data are given on the comparative effectiveness of the intravenous and oral administration of these agents. Ritmilen is highly effective in ventricular extrasystole in the presence of slow sinus rhythm.

[Evaluation of the heart conduction system in patients with ventricular allorhythmia]. / Otsenka provodiashchei sistemy serdtsa u bol'nykh s zheludochkovymi alloritmiiami.

Intracardiac electrophysiologic studies of the sinus node and conductive system of the heart were carried out in 51 patients with ventricular allorhythmias. In half of the cases, ventricular allorhythmias occurred in patients with impaired sinus node operation and abnormal atrioventricular impulse conduction. It is suggested that anti-arrhythmic drugs associated with adverse chrono- and dromotropic effects should be used with caution.

[DNA replication in HeLa cells after gamma irradiation. I. The period of DNA replicative synthesis after the irradiation of cells in the G1 phase with gamma rays in large doses]. / Replikatsiia DNK v kletkakh HeLa posle gamma-oblucheniia. I. Period replikativnogo sinteza DNK posle oblucheniia kletok v faze G1 gamma-luchami v bol'shikh dozakh.

HeLa G-63 cells irradiated by 5 krads of 60 Co-gamma-rays during their G1-period pass through the S-period of the same interphase just as do non-irradiated cells: the kinetics of labeled cells upon a 30 min incubation with 3H-TdR (radioautography) is the same for both irradiated and non-irradiated cell populations; the rate of 3H-thymidine incorporation during the S-period upon a 3H-TdR continuous incubation is the same for both the cell populations; the mean DNA content per nucleus of irradiated cell is doubled after the S-period (cytophotometry). With increasing the radiation dose (from 10 to 30 krads), the rate of 3H-TdR incorporation into cells falls, and the S-period is prolonged.

[The effect of ultraviolet radiation of different wave lengths on the concentration of DNA--fuchsin in the cells of Zajdel's ascitic hepatoma]. / Vliianie UF izlucheniia raznoi dliny volny na soderzhanie DNK--fuksina v kletkakh astsitnoi gepatomy Zaidela

The cytophotometrical analysis of the relationships between the content of DNA--fuchsin and the duration of acid hydrolysis of the intranuclear DNA (the Feulgen reaction) in the Zaidela hepatoma cells allows to see the degree of the DNA--protein binding. The UV irradiation of different wave-lengths (254, 325 and 365 nm, resp.) irrespective of the degree of absorption by nucleic acids, causes changes in chromatin condensation, thus suggesting the labilization of DNA--protein bounds.