A METHOD FOR IMPROVING THE PROFESSIONAL PERFORMANCE AND RELIABILITY OF PERSONS DRIVING HIGH-SPEED VEHICLES.

Recently, due to the emergence of a variety of modifications of air, land, water vehicles and an increase in their speed and maneuverability, the number of people with severe manifestations of motion sickness has also increased. The relevance of this problem is dictated by the fact that, despite significant achievements in the field of preventive medicine, a significant number of people prone to motion sickness have been observed to date. Thus, among persons using land modes of transport, the percentage of sick people reaches 15.0%, air modes 20.0%, while using water modes of transport, the number of sick people reaches 30.0%. The significance of this problem is dictated by the fact that the psycho-physiological capabilities of our body do not keep pace with the rapidly increasing speed-maneuvering characteristics of vehicles.

Asymmetric excitable phase triggering in an optically injected semiconductor laser.

One of the defining characteristics of excitability is the existence of an excitable threshold: the minimum perturbation amplitude necessary to produce an excitable response. We analyze an optically injected dual state quantum dot laser, previously shown to display a dual state stochastic excitable dynamic. We show that deterministic triggering of this dynamic can be achieved via optical phase perturbations. Further, we demonstrate that there are in fact two asymmetric excitable thresholds in this system corresponding to the two possible directions of optical phase perturbations. For fast enough perturbations, an excitable interval arises, and there is a limit to the perturbation amplitude, above which excitations no longer arise, a phenomenon heretofore unobserved in studies of excitability.

Aurore: A platform for ultrafast sciences.

We present the Aurore platform for ultrafast sciences. This platform is based on a unique 20 W, 1 kHz, 26 fs Ti:sapphire laser system designed for reliable operation and high intensity temporal contrast. The specific design ensures the high stability in terms of pulse duration, energy, and beam pointing necessary for extended experimental campaigns. The laser supplies 5 different beamlines, all dedicated to a specific field: attosecond science (Aurore 1), ultrafast phase transitions in solids (Aurore 2 and 3), ultrafast luminescence in solids (Aurore 4), and femtochemistry (Aurore 5). The technical specifications of these five beamlines are described in detail, and examples of the recent results are given.

Efficiency of a cubic NaI(Tl) detector with rectangular cavity using standard radioactive point sources placed at non-axial position.

Low cost scintillation detectors as compared with HPGe detectors are considered to be one of most important radiation detection tools. Therefore, these detectors can be manufactured in different shapes and work at room temperature without any cooling systems, which added an extra advantage to it. This work presents a study of a cubic detector with a rectangular cavity in different experimental setup geometries, using standard point-like gamma-ray sources, where the efficiency of the detector in these geometries was the target to be studied. According to this aim, the data from the experimental measurements was used to determine the detector efficiency. An analytical calculation of the detector efficiency was done by using a new mathematical expression, this mathematical expression depends on the efficiency transfer technique and effective solid angle calculations. To support the mathematical model, the source-to-detector arrangement was simulated by Geant4 Monte Carlo code. All the compared efficiency results were found to be promising and trusted based on the calculated deviation percentages.

Excitable interplay between lasing quantum dot states.

The optically injected semiconductor laser system has proven to be an excellent source of experimental nonlinear dynamics, particularly regarding the generation of excitable pulses. Typically for low-injection strengths, these pulses are the result of a small above-threshold perturbation of a stable steady state, the underlying physics is well described by the Adler phase equation, and each laser intensity pulse is accompanied by a 2π phase rotation. In this article, we show how, with a dual-state quantum dot laser, a variation of type I excitability is possible that cannot be described by the Adler model. The laser is operated so that emission is from the excited state only. The ground state can be activated and phase locked to the master laser via optical injection while the excited state is completely suppressed. Close to the phase-locking boundary, a region of ground-state emission dropouts correlated to excited-state pulses can be observed. We show that the phase of the ground state undergoes bounded rotations due to interactions with the excited state. We analyze the system both experimentally and numerically and find excellent agreement. Particular attention is devoted to the bifurcation conditions needed for an excitable pulse as well as its time evolution.

Wavelength scaling of terahertz pulse energies delivered by two-color air plasmas.

We address the long-standing problem of anomalous growth observed in the terahertz (THz) energy yield from air plasmas created by two-color laser pulses, as the fundamental wavelength λ0 is increased. Using two distinct optical parametric amplifiers (OPAs), we report THz energies scaling like λ0α with large exponents 5.6≤α≤14.3, which departs from the growth in λ02 expected from photocurrent theory. By means of comprehensive 3D simulations, we demonstrate that the changes in the laser beam size, pulse duration, and phase-matching conditions in the second-harmonic generation process when tuning the OPA's carrier wavelength can lead to these high scaling powers. The value of the phase angle between the two colors reached at the exit of the doubling crystal turns out to be crucial and even explains non-monotonic behaviors in the measurements.

Injection-induced, tunable all-optical gating in a two-state quantum dot laser.

We demonstrate a tunable all-optical gating phenomenon in a single-section quantum dot laser. The free-running operation of the device is emission from the excited state. Optical injection into the ground state of the material can induce a switch to emission from the ground state with complete suppression of the excited state. If the master laser is detuned from the ground-state emitting frequency, a periodic train of ground-state dropouts can be obtained. These dropouts act as gates for excited-state pulsations: during the dropout, the gate is opened and gain is made available for the excited state, and the gate is closed again when the dropout ends. Numerical simulations using a rate equation model are in excellent agreement with experimental results.

Enhanced photoemission from laser-excited plasmonic nano-objects in periodic arrays.

The process of photoelectron emission from gold surfaces covered with nano-objects that are organized in the form of a periodic array is addressed in the short laser pulse regime ([Formula: see text] fs) at moderate intensities [Formula: see text] W cm(-2) and for various laser wavelengths. The emission spectrum from a gold single crystal measured under the same conditions is used for reference. The comparison of the photo-emission yield and the energy of the ejected electrons with their counterparts from the (more simple) reference system shows that the periodic conditions imposed on the target surface drastically enhance both quantities. In addition to the standard mechanism of Coulomb explosion, a second mechanism comes into play, driven by surface plasmon excitation. This can be clearly demonstrated by varying the laser wavelength. This interpretation of the experimental data is supported by predictions from model calculations that account both for the primary quantum electron emission and for the subsequent surface-plasmon-driven acceleration in the vacuum. Despite the fact that the incident laser intensity is as low as [Formula: see text] W cm(-2), such a structured target permits generating electrons with energies as high as 300 eV. Experiments with two incident laser beams of different wavelengths with an adjustable delay, have also been carried out. The results show that there exist various channels for the decay of the photo-emission signal, depending on the target type. These observations are shedding light on the various relaxation mechanisms that take place on different timescales.

Optically induced hysteresis in a two-state quantum dot laser.

Quantum dot lasers can lase from the ground state only, simultaneously from both the ground and first excited states and from the excited state only. We examine the influence of optical injection at frequencies close to the ground state when the free-running operation of the device is excited state lasing only. We demonstrate the existence of an injection-induced bistability between ground state dominated emission and excited state dominated emission and the consequent hysteresis loop in the lasing output. Experimental and numerical investigations are in excellent agreement. Inhomogeneous broadening is found to be the underlying physical mechanism driving the phenomenon.

Experimental station for laser-based picosecond time-resolved x-ray absorption near-edge spectroscopy.

We present an experimental station designed for time-resolved X-ray Absorption Near-Edge Spectroscopy (XANES). It is based on ultrashort laser-plasma x-ray pulses generated from a table-top 100 mJ-class laser at 10 Hz repetition rate. A high transmission (10%-20%) x-ray beam line transport using polycapillary optics allows us to set the sample in an independent vacuum chamber, providing high flexibility over a wide spectral range from 0.5 up to 4 keV. Some XANES spectra are presented, demonstrating 1% noise level in only ∼1 mn and ∼100 cumulated laser shots. Time-resolved measurements are reported, indicating that the time resolution of the entire experimental station is 3.3 ± 0.6 ps rms.

Multi-channel electronic and vibrational dynamics in polyatomic resonant high-order harmonic generation.

High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence of resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present a multi-modal approach for the investigation of unaligned polyatomic molecules, using SF6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology. Fragment-resolved above-threshold ionization measurements reveal that strong-field ionization opens at least three channels. A shape resonance in one of them is found to dominate the signal in the 20-26 eV range. This resonance induces a phase jump in the harmonic emission, a switch in the polarization state and different dynamical responses to molecular vibrations. This study demonstrates a method for extending high-harmonic spectroscopy to polyatomic molecules, where complex attosecond dynamics are expected.

Efficient broadband 400 nm noncollinear second-harmonic generation of chirped femtosecond laser pulses in BBO and LBO.

We report on 400 nm broadband type I frequency doubling in a noncollinear geometry with pulse-front-tilted and chirped femtosecond pulses (λ =800 nm; Fourier transform limited pulse duration, 45 fs). With moderate power densities (2 to 10 GW/cm2) thus avoiding higher-order nonlinear phenomena, the energy conversion efficiency was up to 65%. Second-harmonic pulses of Fourier transform limited pulse duration shorter than the fundamental wave were generated, exhibiting good beam quality and no pulse-front tilt. High energy (20 mJ/pulse) was produced in a 40 mm diameter and 6 mm thick LBO crystal. To the best of our knowledge, this is the first demonstration of this optical configuration with sub-100-fs pulses. Good agreement between experimental results and simulations is obtained.

Band tail absorption saturation in CdWO4 with 100 fs laser pulses.

The decay kinetics of the excitonic emission of CdWO4 scintillators was studied under excitation by powerful 100 fs laser pulses in the band tail (Urbach) absorption region. A special imaging technique possessing both spatial and temporal resolution provided a unique insight into the Förster dipole-dipole interaction of self-trapped excitons, which is the main cause of the nonlinear quenching of luminescence in this material. In addition, the saturation of phonon-assisted excitonic absorption due to extremely short excitation pulses was discovered. A model describing the evolution of electronic excitations in the conditions of absorption saturation was developed and an earlier model of decay kinetics based on the Förster interaction was extended to include the saturation effect. Compared to the previous studies, a more accurate calculation yields 3.7 nm as the Förster interaction radius. It was shown that exciton-exciton interaction is the main source of scintillation nonproportionality in CdWO4. A quantitative description using a new model of nonproportionality was presented, making use of the corrected value of the Förster radius.

[NAT screening of viral infections in donors enhances blood safety].

The first experience in introducing the nucleic acid amplification technique (NAT) in an Indian blood service as compared with the established European practice is analyzed. Examination of 12,224 donor blood samples revealed 217 (1.78%) persons with markers of infections, including 8 (0.065%) persons only with markers of viral genome, without serological signs of infections. In India, enzyme immunoassay-negative NAT-positive donations were tens of times more detectable than in the developed countries, which is associated with the epidemiological features and the large (more than 50%) proportion of paid donors. By taking into account the fact that 4.6% of the preserved blood doses are annually rejected as defective in the Russian Federation, as evidenced by the screening of markers of infections, the introduction of NAT may be expected to reveal a large proportion of donors in the period of both a "seronegative window" and chronic carriers of hepatitis B virus with its blood content. Both intralaboratory monitoring using the certified standards and the laboratory work quality system as a whole are a necessary condition for introducing NAT into a blood service.

Increase in slow afterhyperpolarization led to learning delay in DBA mice.

We showed that differences in learning capacity between DBA and C57Bl/6 mice correlates with differences in slow afterhyperpolarization amplitude in hippocampal CA1 pyramid neurons. In DBA mice learning capacity is lower, but the amplitude of slow afterhyperpolarizations higher than in C57Bl/6 mice.

[Indices of cholecystokinin secretion, vegetative regulation of heart rate and anxiety level in patients with a motor dysfunction of the gallbladder]. / Pokazateli sekretsii kholetsistokinina, vegetativnoi reguliatsii serdechnogo ritma i uroven' trevozhnosti u bol'nykh s motornoi disfunktsiei zhelchnogo nuzyria.

We examined 36 patients with biliary diseases (14 men and 22 women) at the age of 19-62 (19 patients with chronic non-calculous cholecystitis, 11 patients with cholelithiasis, and 6 patients with gallbladder dysfunctions) as well as 14 practically healthy people from the control group. Methods of the study included dynamic sorbite echography of the gallbladder, determination of serum cholecystokinin by the radioimmunoassay (RIA) as well as examination of variability of the cardiac rate and anxiety level. Patients with a motor dysfunction of the gallbladder suffer from disorders of the correlation between cholecystokinin secretion, the functional state of the vegetative nervous system and the nature of the motor and evacuation function of the gallbladder.

[Effect of vegetotropic pharmacologic preparations of the motor-evacuatory function of the gallbladder in patients with chronic biliary tract pathology]. / Vliianie vegototropnykh farmakologicheskikh preparatov na motorno-évakuatornuiu funkstiiu zhelchnogo puzyria u bol'nykh s khronicheskoi patologiei biliarnogo trakta.

We examined 74 patients at the age of 18-54 with a chronic bilary pathology, including 50 patients with chronic non-calculous cholecystitis, 16 patients with a gallbladder dysfunction, and 8 patients with cholelithiasis. The differentiated correction of the motor gallbladder dysfunction can be carried out on the basis of the analysis of heart rate variability parameters and results of the gallbladder dynamic sorbite echography against the background of the action of vegetotropic pharmacological preparations (Atropine, Propranolol, Metoclopramide, Hymecromone, Cisapride, Amitriptyline).

[Indicators of cholecystokinin secretion, vegetative regulation of cardiac rhythm, and level of anxiety in patients with motor dysfunction of the gall bladder]. / Pokazateli sekretsii kholetsistokinina, vegetativnoi reguliatsii serdechnogo ritma i uroven' trevozhnosti u bol'nykh s motornoi disfunktsiei zhelchnogo puzyria.

We examined 36 patients with biliary diseases (14 males and 22 females) at the age of 19-62 (19 with chronic acalculous cholecystitis, 11 with cholelithiasis, 6 with gall-bladder dysfunction) and 14 practically healthy people as a control group. The examination methods comprised dynamic gall-bladder ultrasonography with Sorbitol, serum cholecystokinin detection with the help of radioimmunoassay, cardiac rate variability and anxiety level tests. Patients with motor gall-bladder dysfunction have derangements of interrelations between cholecystokinin secretion, the functional state of the vegetative nervous system, and the nature of the gall-bladder motor evacuation function.

[Choice of optimal vegetotropic drug therapy in patients with chronic non-calculous cholecystitis combined with gallbladder dyskinesia]. / Vybor optimal'noi vegetotropnoi farmakoterapii u bol'nykh khornicheskim nekal'kuleznym kholetsitom v sochetanii s diskineziei zhelchnogo puzyria.

The group of 117 patients (58 male and 57 female, age from 17 to 54) with chronic non-calculous cholecystitis was examined. The control group included 54 practically healthy persons. The motor-evacuation function of gallbladder was estimated on dynamic ultrasonographic findings of biliary system sorbet. The character of the autonomic regulation was determined on the basis of variability parameters of the heart rhythm. The results of the repeated dynamic ultrasonography of biliary system with sorbet on a background of vegetotropic medications (Atropine, Propranolol, Metoclopramide) have demonstrated that the variability parameters of heart rhythm can be used for an estimation of the autonomic regulation type and can become the basis of vegetotropic pharmacotherapy choice for the patients with chronic non-calculous cholecystitis and biliary dyskinesia.