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.

When mechanisms of coalescence and sintering at the nanoscale fundamentally differ: Molecular dynamics study.

Employing classical isothermal molecular dynamics, we simulated coalescence of mesoscopic Au nanodroplets, containing from several thousands to several hundred thousands of atoms, and sintering of mesoscopic solid Au nanoparticles. For our atomistic simulations, we used the embedded atom method. The employed open access program large-scale atomic/molecular massively parallel simulator makes it possible to realize parallel graphical processing unit calculations. We have made a conclusion that the regularities and mechanisms of the nanodroplet coalescence (temperature is higher than the nanoparticle melting temperature) and of the solid nanoparticle sintering differ from each other. We have also concluded that the nanodroplet coalescence may be interpreted as a hydrodynamic phenomenon at the nanoscale whereas sintering of solid nanoparticles is a much more complex phenomenon related to different mechanisms, including collective rearrangements of atoms, the surface diffusion, and other types of diffusion. At the same time, collective rearrangements of atoms relate not only to the solid nanoparticle sintering but also to the nanodroplet coalescence. In general, our molecular dynamics results on sintering of Au nanoparticles consisting of 10 000-30 000 atoms agree with the Ferrando-Minnai kinetic trapping concept that was earlier confirmed in molecular dynamics experiments on Au nanoclusters consisting of about 100 atoms.

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.

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.

[Circulating regulatory T-cells and changes in the subpopulation composition of lymphocytes in colorectal cancer patients].

Data on the frequency of peripheral Treg cells, their functional activity, as well as their relationship to changes in characteristics of cellular immunity in patients with colorectal cancer (CRC, n=42) and healthy donors (n=34) are presented in the article. Assessment of the expression of molecular markers of lymphocytes was performed by multicolor flow cytometry. It was shown that the number of these cells is significantly increased in CRC patients (p<0,05). Probably CD4+CD25+FOXP3+ Treg cells may play a more substantial role in the periphery during the initial period of tumor formation, whereas CD8+FOXP3+ Treg cells are important in the later stages of the disease. In CRC patients, the increase of the functional activity of Treg cells (CD4+CD25+CD127lo/') on the expression of inhibitory molecules CTLA-4 and the marker of cell proliferation Ki-67 was observed. In patients with CRC, the frequency of peripheral Treg cells and the expression level of CTLA-4 were inversely correlated with the number of CD3+CD4+ T-helper cells.

[Microdialysis--a new method of monitoring of the transplanted cadaveric kidneys function].

PURPOSE: To assess ischemia-reperfusion injury of renal allograft by microdialysis. DESIGN: A pilot, single-center; prospective study. PATIENTS AND METHODS: The study included 7 patients (4 males and 3 females, average age was 46.71 ± 6.53 years) after cadaveric kidney allograft transplantation (CKA) under general combined anaesthesia. CONCLUSIONS: Microdialysis provides an opportunity of continuous monitoring of metabolic changes in the tissue of transplanted kidney. The main advantage of the monitoring by microdialysis is an opportunity of early identifying of ischemia-reperfusion complications. Thus, early assessment of CKA by microdialysis can be for the improving of patient's treatment in the early post operative period. Further clinical studies must be done to define the role of microdialysis.

[Tumor markers at the preoperative examination and monitoring of surgical treatment of patients with colorectal cancer].

Comparative analysis of using tumor markers in 159 patients with colorectal cancer was made. Carcinoembryonal antigen, skin reaction of hypersensitivity of slow type with autologous modified lymphocytes and a diagnostic test of tumor growth were used as oncomarkers. Each of three markers may be used for preoperative staging of colorectal cancer, postoperative monitoring of patients and determination of the disease prognosis. An individual approach of assessment of the oncomarker level at different stages of examining the patient is recommended.

[Changes in markers of systemic inflammatory response and functional state of the vascular wall in patients with early syphilis].

The purpose of the study was to assess the functional state of endothelium and vascular stiffness using biochemical parameters and non-invasive instrumental methods of examination before and after specific treatment of patients with early forms of syphilis. A total of 51 patients with early syphilis were examined, 30 healthy individuals served as controls. Blood C-reactive protein, fibrinogen, and sialic acid levels were measured. Rigidity index was estimated using a Pulse Trace photopletizmograph (Micro Medical, England). Patients with early forms of syphilis had markedly increased concentrations of CRP, fibrinogen, sialic acids (markers of inflammation) and the ridgidity index both before and after specific therapy.

[Detection of structural changes of large arteries by characteristics of peripheral pulse wave: comparison with high resolution ultrasonic investigation].

AIM: To compare high-resolution ultrasound of major arteries and the method of vascular stiffness evaluation by digital volume pulse photoplethysmography after sublingual nitroglycerin in diagnosis of structural vascular changes. MATERIAL AND METHODS: The comparison of the two methods was made in 110 volunteers (mean age 31.9 +/- 11.5 years). The study protocol included measurement of blood pressure (BP), blood lipids and glucose, evaluation of IMT of the carotid arteries by ultrasonography, baseline stiffness index (SIbl) and after sublingual nitroglycerin (SIng) by photoplethysmography. Reproducibility of photoplethysmography was evaluated in 20 volunteers (mean age 20.3 +/- 1.4 years) with repeated measurement after 1 week. The results were tested in 40 volunteers of different age groups. RESULTS: There were significant correlations of IMT, SIbl and SIng with risk factors and close interrelations of these parameters. SIng better explained variability of IMT compared to SIbl (r = 0.79, R2 = 0.62, p < 0.001 versus r = 0.67, R2 = 0.45, p < 0.001, respectively). Relations of IMT with risk factors were lost after correction for SIng. Reproducibility of SIng was higher than SIbl (+/- 5.1% versus +/- 10.9%, respectively) and than those for IMT found in the literature. Mean IMT values for random sample evaluated by ultrasonography and calculated by estimated equation of linear regression for SIng and IMT did not differ significantly (0.576 +/- 0.087 mm versus 0.570 +/- 0.074 mm, p = 0.44; r = 0.71, p < 0.001, mean difference 0.007 +/- 0.051 mm). CONCLUSION: The method of vascular stiffness measurement is comparable with ultrasonography in terms of vessel structure evaluation and possesses higher reproducibility. The test with nitroglycerin substantially increases its diagnostic potential and reproducibility.

[Alveolar opening maneuver (mobilization) in intraoperative pulmonary oxygenizing dysfunction in cardiosurgical patients].

The purpose of the study was to investigate arterial oxygenation and hemodynamics during and after alveolar mobilization in the early post-cardiopulmonary bypass (CPB) period of cardiac surgery. The study involved 21 patients aged 30 to 73 years, who had a PaO2/FiO2 below 300 mm Hg in the early post-CPB period. PaO2/FiO2 was less than 200 mm Hg in 4 patients. Alveolar mobilization was performed by means of the "Open lung tool" function of a Servo-i respirator ("Maquet'). PaO2/FiO2 significantly increased (P < 0.5) from 244+/-11 to 472+/-20 mm Hg and thoracopulmonary compliance (Cdyn) increased from 53.3+/-3 to 67.5+/-2.9 ml/cm H20 (p < 0.5). Intrapulmonary shunt (Qs/Qt) significantly decreased from 14+/-1 to 10+/-1.5% (p < 0.5). The mean values of PaO2/FiO2 Cdyn and Qs/Qt were stable at the end of procedures. PaO/FiO, was greater than 350 mm Hg in 62% of the patients. Cardiac index considerably decreased from 2.7+/-0.1 to 225+/-0.1 l/min/m(2) at the peak of alveolar mobilization (p < 0.05); right atrial pressure and mean pulmonary artery pressure were moderately, but significantly higher at that moment. Hemodynamic parameters returned to the baseline levels after alveolar mobilization. There were no significant hemodynamic complications. It is concluded that alveolar mobilization is an effective technique in improving arterial oxygenation and lung biomechanics in cardiosurgical patients under anesthesia.

[Comprehensive characteristics of the pulmonary syndrome in chronic liver diseases]. / Kompleksnaia kharakteristika legochnogo sindroma pri khronicheskikh zabolevaniiakh pecheni.

Combined investigations have shown that the pulmonary syndrome in chronic liver diseases is a group of changes (heterogeneous in their structure and origin), most of which are of intercurrent nature (chronic bronchitis and its complications, chronic pneumonia), the lesser part of them is related directly to an inflammatory liver process and constitutes the true pulmonary syndrome (interstitial pneumonitis, fibrosing alveolitis). In view of the fact that chronic liver pathology is attended by concomitant disorders of pulmonary ventilation, hemodynamics and immunologic homestasis, the authors propose that they should be regarded as a risk factor contributing to the development of respiratory diseases.