Study of amplifying characteristics of copper bromide active media operating at the increased superradiance pulse duration mode

Amplifying characteristics of the copper bromide vapor active media with the increased inversion duration are studied using the detailed kinetic modeling. The analysis of the gain radial profile and its time evolution at various points of the GDT profile is presented. The results show the possibility of application such active media to the tasks of the remote object visualization

Mathematical Modeling of Training and Dynamics of Scientific Personnel

Qualitative and numerical analysis of mathematical model of training and dynamics of scientific personnel, which is a dynamic system of third order, describing the interaction of scientific personnel without degrees, candidates and doctors of sciences were don

Patterns of nucleotide diversity for different domains of centromeric histone H3 (CENH3) gene in Secale L.

Rye (Secale) is among staple cereals along with other members of the Triticeae tribe: wheat and barley. The genus Secale includes perennial and annual, cross-pollinating and self-pollinating species, and they can be donors of valuable genes in wheat and rye breeding programs. Studies of the structure of the gene for centromeric histone H3 (CENH3), essential for centromere functions, are relevant to the breeding of agronomically important crops. We have investigated the nucleotide diversity of sequences of two variants of the rye CENH3 gene inside the N-terminal tail (NTT) and the conservative HFD (histone fold domain) domain in the genus Secale. The mean values of nucleotide diversity in the NTT and HFD of wild cross- and self-pollinating taxa are close in αCENH3: πtot = 0.0176–0.0090 and 0.0136–0. 0052, respectively. In the case of βCENH3, the mean values for NTT (πtot = 0.0168–0.0062) are lower than for HFD (πtot = 0.0259–0.084). The estimates of nucleotide and haplotype diversity per site for the CENH3 domains are considerably lower in taxa with narrow geographic ranges: S. cereale subsp. dighoricum and S. strictum subsp. kuprijanovii. Commercial breeding reduces the nucleotide sequence variability in αCENH3 and βCENH3. Cultivated rye varieties have π values within 0.0122–0.0014. The nucleotide and haplotype diversity values in αCENH3 and βCENH3 are close in S. sylvestre, which is believed to be the oldest rye species. The results of this study prove that the frequency of single nucleotide polymorphisms and nucleotide diversity of sequences in genes for CENH3 in Secale species are influenced by numerous factors, including reproduction habits, the geographic isolation of taxa, breeding, and the evolutionary age of species

Brittle porous material mesovolume structure models and simulation of their mechanical properties

To study the mechanical response of brittle porous materials at mesoscale, porous samples were generated and their deformation was numerically modelled. Two types of pore space morphology such as overlapping spherical pores and overlapping spherical solids were explicitly considered. For deformation modelling, an evolutionary approach including the nonlinear constitutive equations used to describe damage accumulation and its impact on the degradation of the solid frame strength properties was applied. The numerical results have shown that an average stress-strain diagram is sensitive to pore morphology as well as porosity

Radial distribution of a single-pass amplified radiation in the active elements of CuBr lasers

The paper presents the results of study of single-pass amplified radiation distribution of copper bromide vapor laser active elements used in high-speed laser monitors. The possibility of modifying the profile of a single-pass amplified light beam by changing the copper bromide vapor concentration is demonstrated. This means of influence on the radiation profile seems to be easiest due to implementation by varying only one parameter of operation. Gaussian, ring-shaped or flat profiles can be achieved depending on the temperature of the containers with copper bromide. The diameter of the beam becomes narrower when increasing the concentration of copper bromide vapor. This feature is characteristic of the discharge tubes as small (diameter 2.5, length 5 cm) and large (diameter 5 cm, length 90 cm) active volume

On the variability of teaching mathematical methods modeling bachelors profiling «Technology and process management in the welding industry»

Actuality and characterized the main features of variable teaching methods of mathematical modeling bachelors profiling «Technology and technology management in the welding industry»Обосновывается актуальность и характеризуются основные особенности вариативного обучения методам математического моделирования бакалавров профилизации «Технологии и технологический менеджмент в сварочном производстве

Measured Radiation and Background Levels During Transmission of Megawatt Electron Beams Through Millimeter Apertures

We report measurements of photon and neutron radiation levels observed while transmitting a 0.43 MW electron beam through millimeter-sized apertures and during beam-off, but accelerating gradient RF-on, operation. These measurements were conducted at the Free-Electron Laser (FEL) facility of the Jefferson National Accelerator Laboratory (JLab) using a 100 MeV electron beam from an energy-recovery linear accelerator. The beam was directed successively through 6 mm, 4 mm, and 2 mm diameter apertures of length 127 mm in aluminum at a maximum current of 4.3 mA (430 kW beam power). This study was conducted to characterize radiation levels for experiments that need to operate in this environment, such as the proposed DarkLight Experiment. We find that sustained transmission of a 430 kW continuous-wave (CW) beam through a 2 mm aperture is feasible with manageable beam-related backgrounds. We also find that during beam-off, RF-on operation, multipactoring inside the niobium cavities of the accelerator cryomodules is the primary source of ambient radiation when the machine is tuned for 130 MeV operation.Comment: 9 pages, 11 figures, submitted to Nuclear Instruments and Methods in Physics Research Section

Transmission of High-Power Electron Beams Through Small Apertures

Tests were performed to pass a 100 MeV, 430 kWatt c.w. electron beam from the energy-recovery linac at the Jefferson Laboratory's FEL facility through a set of small apertures in a 127 mm long aluminum block. Beam transmission losses of 3 p.p.m. through a 2 mm diameter aperture were maintained during a 7 hour continuous run.Comment: arXiv admin note: text overlap with arXiv:1305.019

A new endosymbiotic bacterium species associated with a nematode species of the genus Xiphinema (Nematoda, Longidoridae)

2021 virtual edition of the Conference Microscopy at the Frontiers of Science, september 29 and October 1st.Nematodes are the third largest group of metazoans; among them, the Family Longidoridae comprises two main genera of plant parasitic nematodes, Xiphinema and Longidorus, which contain several virus-vector species, e.g. the species X. index, the vector of grape fanleaf virus (GFLV), a serious pathogen of grapes. Bacterial endosymbionts of plant-parasitic nematodes represent a field of research that has become active in recent years. In this work we present a detailed characterization of the endosymbiont bacterium found in the nematode X. pachtaicum from the rhizosphere of sour orange trees (Citrus x aurantium L.) from Cordoba, Spain, and, based on morphological, phylogenetic and genomic characteristics propose a novel candidate genus and species for this uncultured bacterium (strain IAST). An intracellular bacterium, strain IAST, was observed to infect several species of the plant-parasitic nematode genus Xiphinema (X. astaregiense, X. incertum, X. madeirense, X. pachtaicum, X. parapachydermum and X. vallense). The bacterium could not be recovered on axenic medium. The localization of the bacterium (via light and fluorescence in situ hybridization microscopy) is in the X. pachtaicum females clustered around the developing oocytes, primarily found embedded inside the epithelial wall cells of the ovaries, from where they are dispersed in the intestine. Transmission electron microscopy (TEM) observations supported the presence of bacteria inside the nematode body, where they occupy ovaries and occur inside the intestinal epithelium. Ultrastructural analysis of the bacterium showed cells that appear as mostly irregular, slightly curved rods with rounded ends, 0.8–1.2 μm wide and 2.5–6.0 μm long, possessing a typical Gram-negative cell wall. The peptidoglycan layer is, however, evident only occasionally and not detectable by TEM in most cells. Another irregularly occurring shell surrounding the endosymbiont cells or the cell clusters was also revealed, probably originating from the host cell membrane. Flagella or spore-like cells do not occur and the nucleoid is diffusely distributed throughout the cell. This endosymbiont is transmitted vertically through nematode generations. These results support the proposal of IAST as a new species, although its obligate intracellular and obligate endosymbiont nature prevented isolation of a definitive type strain. Strain IAST is therefore proposed as representing ‘Candidatus Xiphinematincola pachtaicus’ gen. nov., sp. nov