Spatial-spectral complexity in Kerr beam self-cleaning.

We report on a comprehensive experimental investigation into the spatial-spectral complexity of the laser beam during Kerr-induced beam self-cleaning in graded-index multimode fibers. We demonstrate the self-cleaning of beams using both transform-limited and chirped femtosecond pulses. By utilizing the spectrally resolved imaging technique, we examine variations in beam homogeneity during the beam cleanup process and reveal correlations observed among spatial beam profiles at different wavelengths for the various cleaned pulses. Our results significantly advance our understanding of Kerr-induced self-cleaning with chirped ultrafast pulses and offer new possibilities for diverse applications.

Improving techniques for diagnostics of laser pulses by compact representations.

We propose and demonstrate, numerically and experimentally, use of sparsity as prior information for extending the capabilities and performance of techniques and devices for laser pulse diagnostics. We apply the concept of sparsity in three different applications. First, we improve a photodiode-oscilloscope system's resolution for measuring the intensity structure of laser pulses. Second, we demonstrate the intensity profile reconstruction of ultrashort laser pulses from intensity autocorrelation measurements. Finally, we use a sparse representation of pulses (amplitudes and phases) to retrieve measured pulses from incomplete spectrograms of cross-correlation frequency-resolved optical gating traces.

Sparsity-based single-shot subwavelength coherent diffractive imaging.

Coherent Diffractive Imaging (CDI) is an algorithmic imaging technique where intricate features are reconstructed from measurements of the freely diffracting intensity pattern. An important goal of such lensless imaging methods is to study the structure of molecules that cannot be crystallized. Ideally, one would want to perform CDI at the highest achievable spatial resolution and in a single-shot measurement such that it could be applied to imaging of ultrafast events. However, the resolution of current CDI techniques is limited by the diffraction limit, hence they cannot resolve features smaller than one half the wavelength of the illuminating light. Here, we present sparsity-based single-shot subwavelength resolution CDI: algorithmic reconstruction of subwavelength features from far-field intensity patterns, at a resolution several times better than the diffraction limit. This work paves the way for subwavelength CDI at ultrafast rates, and it can considerably improve the CDI resolution with X-ray free-electron lasers and high harmonics.

[The results of the cytogenetic monitoring of the species of angiosperm plants growing in the area of the radionuclide contamination after the accident at the Chernobyl Atomic Electric Power Station]. / Rezul'taty tsitogeneticheskogo monitoringa vidov pokrytosemennykh rastenii, proizrastaiushchikh v zone radionuklidnogo zagriazneniia posle avarii na Chernobyl'skoi AES.

Results of investigations of meiosis in microsporogenesis, sporads and pollen grains as well as mitosis in root meristematic cells in 94 species of angiosperms (from 28 families) growing in different ecological conditions in the zone with higher radionuclide pollution after the Ch.NPS accident are present. The low percentage (0.5-2.0%) of anomalies on investigating parameters has been revealed in the majority of species, only in certain species (8-10%) the correlation between an increase of the number of anomalies and an increase of the gamma-radiation level was shown. The data obtained make evident the resistance of the seed reproduction system in higher plants to chronic irradiation by the low doses of ionising radiation.

Alterations in adenylate ratios in plant cells after accelerated ion irradiation.

Levels of adenylate metabolism have been studied in cells of Nicotiana tabacum growing in vitro, and in root apex extracts of Pisum sativum irradiated at the 95-in. isochronous cyclotron U-240, Institute for Nuclear Research, Ukrainian National Academy of Sciences, Kyiv. Particle beams of accelerated helium ions with energy 9.34 keV/micrometer were used. Replacement and rapid freezing of the irradiated plants samples in liquid nitrogen were carried out with a manipulator and a remote control system. After doses of 5, 20, 50, and 100 Gy of gamma-irradiation, as well as 50 and 100 Gy 4He irradiation, the cellular ATP/ADP ratio increased during early stages of the response. This effect was absent at higher doses and after exposure to sparesly-ionizing radiation, when a rapid decline in the cellular ATP concentration and the ATP/ADP ratio occurred.

Induction of micronuclei in plant cells after exposure to accelerated ion irradiation.

The root apex cells of Pisum sativum were irradiated in an U-240 isochronous cyclotron at the Institute for Nuclear Research of the Ukrainian National Academy of Sciences, Kyiv. Several types of micronuclei, differing in structural peculiarities, were observed in the 84 h following exposure to beams of accelerated 1H, 4He, and 14N ions with linear energy transfer (LET) of 0.95, 9.34, and 221 keV/microns, respectively. The maximum micronucleus induction was observed after irradiation with helium ions. Results obtained show that the micronucleus assay is a responsive test for investigations of cytogenetic damage produced by high LET beams in dividing cell systems in vivo.

[The initial experience of using fraxiparin in extracorporeal detoxication in clinical cardiology]. / Pervyi opyt primeneniia fraksiparina pri ékstrakorporal'noi detoksikatsii v klinicheskoi kardiologii.

Procedures, connected with extracorporal blood circulation--hemodialysis, hemosorption and plasmapheresis--were used in complex of treatment in 30 patients with various cardiovascular diseases. As an anticoagulant in 8 patients was used the preparation of low molecular heparine (Fraxiparine) produced by "Sanofi" (France) firm, and in 22-heparin, produced by "Polfa" (Poland). Ascertained advantages of Fraxiparine versus heparin were: possibility of single injection of preparation, the reducing of total dose magnitude, which is needed for one curative act conduction, lowering by 70% approximately the hemorrhagic complications rate.

Prospects of autotrophic link functioning in biological life-support systems based on cell biology studies.

On the basis of using of modern methods of cytological analysis the cell growth peculiarities, reproduction and structure of plant cells of different level organisation (unicellular algae, mosses, angiosperms, cell cultures of higher factors--weightlessness, hypogravity, magnetic fields of various intensity, vibration and acceleration were cleared. It is shown that many discovered biological effects of space flight are connected with the degree of complexity of the object organisation and intensified with the increasing duration of influence.

[Energy requirements of sugar beet growers]. / Energeticheskaia potrebnost' sveklovodov.

Energy requirements were determined on the average for female sugar-beet raisers during the main labour processes as follows (kcal/min): 3.64 during weeding 2.03 during manual separation of sugar-beet roots from beet tops, and 4.05 in the course of sugar-beet pulling from the soil. Daily energy requirement amounted on the average to 3577 kcal during care on sugar-beet crops and to 3272 kcal during harvesting.