Streaking camera in the high intensity regime.

The laser-induced decay of an atomic system in an intense infrared and perturbative extreme ultraviolet (XUV) pulse is considered within Keldysh and streaking ionization channels. The streak camera method is discussed for two cases corresponding to different ranges of photoelectron momentum: i) the streaking channel significantly dominates the Keldysh channel and ii) the Keldysh channel of ionization is dominant, while two channels may interfere. The retrieval of XUV pulse parameters for these two cases is discussed and supported by numerical calculations.

Channel separation of secondary generated radiation induced by orthogonal XUV and IR pulses.

The secondary generated radiation induced by orthogonal linearly polarized extreme ultraviolet (XUV) and infrared (IR) pulses is analyzed for the spectral region of the second XUV harmonic. The polarization-filtering-based method is utilized to separate two spectrally overlapping and competing channels, which are the XUV second harmonic generation (SHG) by IR-dressed atom and XUV-assisted recombination channel of high-order harmonic generation in the IR field [Phys. Rev. A98, 063433 (2018)10.1103/PhysRevA.98.063433]. We demonstrate the use of the separated XUV SHG channel for accurately retrieving the IR-pulse waveform and find the range of IR-pulse intensities for which this retrieving is applicable.

Using the generation of Brunel harmonics by elliptically polarized laser pulses for high-resolution detecting lower-frequency radiation.

We propose to use the generation of even Brunel harmonics (BHs) by optical laser pulses for high-resolution gas-biased coherent detection of lower-frequency radiation in terahertz and mid-infrared ranges. BHs arise due to the acceleration of electrons liberated in the tunneling ionization process, and BHs pulses are much shorter than the laser ones. The latter makes it possible to significantly increase the temporal resolution of sampling detection compared to the use of cubic response of bound electrons generating the second harmonic of the gating pulse. However, as we show by solving the time-dependent Schrödinger equation for the helium atom, for an intense linearly polarized laser pulse, the atomic response contains a broadband noise signal that interferes with BHs and allows the detection of very high electric fields only. We show that the nature of this noise is related to the population of the Rydberg states of the atom, which can be effectively suppressed by using elliptical polarization of the gating pulse.

Contribution of the collective electron dynamics to the polarization response of an atom subjected to intense IR and weak XUV pulses.

We analyze the polarization response of a single Ne atom in an intense infrared (IR) laser field and weak extreme ultraviolet (XUV) isolated attosecond pulse (IAP). The analysis is based on the numerical solution of the time-dependent Kohn-Sham equations and the recently developed perturbation theory in the XUV field for an atom subjected to an intense IR field. In our numerical results, we observe a significant increase in the magnitude of the atomic polarization response at the frequencies near the carrier frequency of the IAP and associate it with XUV-induced collective dynamics contributing to the polarizability of Ne. The specific interference between IR- and XUV-induced channels is discussed, and its utilization for retrieving the phase of the generated harmonics in the IR field is suggested.

Waveform retrieving of an isolated attosecond pulse using high-order harmonics generation of the superimposed infrared field.

An all-optical method is suggested for the metrology of an isolated, pulse-to-pulse stabilized attosecond pulse. It is shown analytically that high-order harmonic generation (HHG) yield for an intense IR pulse and time-delayed attosecond pulse keeps encoded waveform of the attopulse, which can be decoded by the time delay measurements of the HHG yield. The retrieval method is demonstrated by modeling HHG from Ne atom within time-dependent Kohn-Sham equations. The application of the suggested method for monitoring the carrier-envelope phase of the attosecond pulse is discussed.

Time-frequency analysis of high harmonic generation using a probe XUV pulse.

Interpretation of strong-field phenomena is mostly based on the analysis of classical electron trajectories in an intense laser field, whose specific properties determine general features of nonlinear laser-matter interaction. Currently, the visualization of closed electron trajectories contributing to high harmonic generation (HHG) of the laser field is the prerogative of a theoretical analysis based on the time-frequency spectrogram of the induced dipole acceleration. Here, we propose a method for direct reconstruction of the HHG time-frequency spectrogram using a time-delayed probe XUV pulse. Our analytical theory and ab initio numerical simulations demonstrate that the XUV-assisted HHG yield as a function of time delay and harmonic energy mimics the short-time Fourier transform of the dipole acceleration induced by the laser field, thereby providing possible in-situ experimental access for tracing electron dynamics in strong-field phenomena.

[Hybrid treatment of total thrombosis of the inferior vena cava]. / Gibridnoe lechenie total'nogo tromboza nizhnei poloi veny.

Described in the article is a clinical case report regarding successful surgical treatment of a female patient with total floating thrombosis of the inferior vena cava and thrombosis of the right atrium, complicated by pulmonary embolism. Our patient was a 42-year-old woman presenting with a clinical pattern of iliofemoral thrombosis. The examination revealed floating thrombosis of the inferior venal cava, right atrial thrombosis, and massive pulmonary embolism. Given the presence of absolute contraindications to systemic thrombolysis, it was decided to carry out surgical treatment by means of a hybrid-operation procedure. The woman underwent successful direct thrombectomy from the right-atrium cavity and branches of the pulmonary artery in conditions of artificial blood circulation, simultaneously accompanied by removing the floating thrombus from the inferior vena cava with the help of the 'Track' system, as well as by placement of a cava filter. Also presented herein is a review of the world experience gained in treating this pathology, followed by substantiation of using a hybrid approach for achieving an optimal clinical outcome.

Generation of tunable mid- and far-infrared pulses during gas ionization by a chirped two-color laser field.

We propose and investigate a method for generating tunable and phase-controllable mid- and far-infrared pulses in gas ionized by an intense two-color laser field composed of the chirped fundamental and its second-harmonic pulses with group time delay. The generation frequency equals the difference between the second-harmonic and the doubled fundamental frequencies and is continuously tunable by varying chirp or time delay. The duration of the generated pulses is determined by the ionization duration, which is much shorter than the ionizing pulse and is controlled by laser-pulse stretching or changing its intensity. Our quantum-mechanical calculations and analytical description show that this method can provide a wide tuning range spanning from several to more than a hundred THz using femtosecond lasers.

Control of Harmonic Generation by the Time Delay Between Two-Color, Bicircular Few-Cycle Mid-IR Laser Pulses.

We study control of high-order harmonic generation (HHG) driven by time-delayed, few-cycle ω and 2ω counterrotating mid-IR pulses. Our numerical and analytical study shows that the time delay between the two-color pulses allows control of the harmonic positions, both those allowed by angular momentum conservation and those seemingly forbidden by it. Moreover, the helicity of any particular harmonic is tunable from left to right circular without changing the driving pulse helicity. The highest HHG yield occurs for a time delay comparable to the fundamental period T=2π/ω.

[Matrix metalloproteinase-1, -8, -9 and the risk of cardiovascular complications in patients with CHD before and after myocardial revascularization].

There is still a great need for detection of biomarkers for early prediction and diagnosis of cardiovascular complications (CVC) in patients with CHD. Objective: To determine the role of MMP-1, 8, 9 in the risk of CCO in patients with CHD before and after coronary artery bypass grafting (CABG). Methods. The study included 75 patients with coronary heart disease before and after myocardial revascularization by CABG, including 40 men and 35 women aged from 45 to 74 years. Patients were divided into two groups: I group - 25 patients with CVC registered after CABG (acute myocardial infarction, ischemic stroke, pulmonary thromboembolism Branch); II group - 50 patients with coronary heart disease without complications after myocardial revascularization. Blood sampling was performed the day before surgery, on the 1st, 3rd and 10th days after CABG. Determining the level of MMP-1, 8, 9 in the serum was performed by ELISA using reagents specific «RD Diagnostics Inc.¼, USA. Results are expressed in ng/ml. Data are presented as medians and quartiles of two (Me, Q25, Q75). Within and between-group differences were evaluated using the Mann - Whitney, Spearman correlation coefficient and c2 test within the application program SPSS №16. Statistically significant differences between the indicators considered when you reject the hypothesis and significance level of p<0,05. Results. A statistically increased concentration of MMP-1 and MMP-8 in patients in group I. Undetermined significant dynamics of MMP-9 in patients after myocardial revascularization. Conclusion. The results indicate that the level of MMP-1, 2.5 ng/ml or more in patients with CAD is a diagnostic criterion for the risk of TE complications. No association between high content of MMP-8 and the presence of complications in patients after surgery. There were no significant dynamics of MMP-9 in patients after myocardial revascularization.

Ionization-Induced Multiwave Mixing: Terahertz Generation with Two-Color Laser Pulses of Various Frequency Ratios.

Ultrafast strong-field ionization is shown to be accompanied by atypical multiwave mixing with the number of mixed waves defined by the dependence of the ionization rate on the field strength. For two-color laser pulses of various frequency ratios, this results in the excitation of a free-electron current at laser combination frequencies and possibly in the excitation of the zero-frequency (residual) current responsible for terahertz (THz) generation in a formed plasma. The high-order nature of ionization-induced wave mixing may cause THz generation with uncommon laser frequency ratios (such as 2:3 and 3:4) to be virtually as effective as that with the commonly used frequency ratio of 1:2.

[THE STUDY OF THE SEVERITY OF EXAM STRESS AND FACTORS WHICH DETERMINE IT IN OLDER SCHOOLCHILDREN].

The study was performed with the help of a questionnaire of views of senior schoolchildren about the objectivity and stressfulness of various forms of the control of knowledge, the level of stress in the exams and measures for its reduction. 53.4% out of the students assess their knowledge in this area as insufficient. The most objective form of the control students consider an oral exam, the least stressful--blank testing. After passing the exams in class 9 we observed the evident reduction of representations of the objectivity of test forms of control. The necessity of the activization of educational work with students on the issues of prevention of exam stress and methodological work on perfection of the organization and content of the forms of Knowledge control is showed.

Two-color laser-plasma generation of terahertz radiation using a frequency-tunable half harmonic of a femtosecond pulse.

We investigate for the first time, both experimentally and theoretically, low-frequency terahertz (THz) emission from the ambient air ionized by a two-color femtosecond laser pulse containing, besides the fundamental-frequency main field, a weak additional field tunable near the frequency of the half harmonic. By controlling the mutual polarization and the powers of the main and additional fields, we determine the dependences of the THz power and polarization on the parameters of the two-color pulse. We also discover the resonantlike dependence of the THz yield on the frequency detuning of the additional field. The analytical formulas obtained using the model of the free-electron residual current density give an excellent agreement with the experimental results.

[Mental and physical development of children living in the area of monitoring pollution from a plant for processing and long-term storage of radioactive waste].

Environmental conditions in the area hosting a plant for processing and long storage of low- to moderately-active radioactive waste are described as reasonably safe. Residence in the area does not exert negative influence on the physical and mental development of children. Several indicators of physical development give better estimates than at the control territory. The difference can be accounted for by a better social situation in the study area (housing conditions, financial standing, food patterns, general lifestyle).

Residual-current excitation in plasmas produced by few-cycle laser pulses.

Along with the generation of extreme-ultraviolet and soft x-ray radiation, gas ionization by an intense few-cycle laser pulse can also induce the generation of low-frequency terahertz waves. The latter is caused by the excitation of a residual quasi-dc current in the produced plasma by the electric field of the laser pulse. We describe this phenomenon using the quantum-mechanical approach based on solving the 3D time-dependent Schrödinger equation. We calculate the dependences of the residual-current density on the carrier-envelope phase, duration, and intensity of the few-cycle laser pulse, and find optimal conditions for high-efficiency realization of the studied phenomenon.

[The late effects of exposure to lead fluoride]. / Otdalennye éffekty vozdeistviia ftorida svintsa.

Effect of lead fluoride dust on the micronuclear reticulocyte content in the bone marrow was shown. Some functional changes in the testicles and increase in the fetal death rate in exposure to 50 mg/m3 of lead fluoride dust were noted.

[Magnesium sulfate as an industrial poison]. / Magniia sul'fata kak promyshlennyi iad.

The article provides information on the hygienic assessment of the labour conditions in magnesium sulphate processing, along with the experimental data on the toxicity of this chemical compound at different ways of its penetration into human body, and describes the damaging mechanisms of its action. The toxicity parameters were related to the 4th class of hazardousness (GOST 12.1.007-76). The acute inhalational action threshold was determined at 112.7 mg/m3. The chemical substance did not exhibit any irritating action on the skin and mucosae, but was capable of penetrating through the undamaged skin and cause some functional disorders. The chronic inhalational action threshold was assessed at 10.2 mg/m3. Magnesium sulphate did not display any specific cardiotoxic or gonadotrophic action. MAC in the air in working zone areas was established at 2 mg/m3. Lesions of the liver were the major factor in the pathogenesis of intoxications.