740 research outputs found

    Study of the island morphology at the early stages of Fe/Mo(110) MBE growth

    Full text link
    We present theoretical study of morphology of Fe islands grown at Mo(110) surface in sub-monolayer MBE mode. We utilize atomistic SOS model with bond counting, and interactions of Fe adatom up to third nearest neighbors. We performed KMC simulations for different values of adatom interactions and varying temperatures. We have found that, while for the low temperature islands are fat fractals, for the temperature 500K islands have faceted rhombic-like shape. For the higher temperature, islands acquire a rounded shape. In order to evaluated qualitatively morphological changes, we measured averaged aspect ration of islands. We calculated dependence of the average aspect ratio on the temperature, and on the strength of interactions of an adatom with neighbors.Comment: 6 pages, 6 figures. Proceedings of 11-th Symposium on Surface Physics, Prague 200

    Enhanced low-energy γ\gamma-decay strength of 70^{70}Ni and its robustness within the shell model

    Full text link
    Neutron-capture reactions on very neutron-rich nuclei are essential for heavy-element nucleosynthesis through the rapid neutron-capture process, now shown to take place in neutron-star merger events. For these exotic nuclei, radiative neutron capture is extremely sensitive to their γ\gamma-emission probability at very low γ\gamma energies. In this work, we present measurements of the γ\gamma-decay strength of 70^{70}Ni over the wide range 1.3Eγ81.3 \leq E_{\gamma} \leq 8 MeV. A significant enhancement is found in the γ\gamma-decay strength for transitions with Eγ<3E_\gamma < 3 MeV. At present, this is the most neutron-rich nucleus displaying this feature, proving that this phenomenon is not restricted to stable nuclei. We have performed E1E1-strength calculations within the quasiparticle time-blocking approximation, which describe our data above Eγ5E_\gamma \simeq 5 MeV very well. Moreover, large-scale shell-model calculations indicate an M1M1 nature of the low-energy γ\gamma strength. This turns out to be remarkably robust with respect to the choice of interaction, truncation and model space, and we predict its presence in the whole isotopic chain, in particular the neutron-rich 72,74,76Ni^{72,74,76}\mathrm{Ni}.Comment: 9 pages, 9 figure

    On-Orbit Measurement of Next Generation Space Solar Cell Technology on the International Space Station

    Get PDF
    Measurement is essential for the evaluation of new photovoltaic (PV) technology for space solar cells. NASA Glenn Research Center (GRC) is in the process of measuring several solar cells in a supplemental experiment on NASA Goddard Space Flight Center's (GSFC) Robotic Refueling Mission's (RRM) Task Board 4 (TB4). Four industry and government partners have provided advanced PV devices for measurement and orbital environment testing. The experiment will be on-orbit for approximately 18 months. It is completely self-contained and will provide its own power and internal data storage. Several new cell technologies including four- junction (4J) Inverted Metamorphic Multijunction (IMM) cells will be evaluated and the results compared to ground-based measurements

    New coronavirus disease 2019 (COVID-19): Is there an impact on male reproductive health

    Get PDF
    The male reproductive health depends on several factors that can be divided into two main groups: the first group, genetic or hereditary (in particular, Klinefelter syndrome, etc.), the second acquired factors that depend on the person's lifestyle (bad habits, diet), stress, infectious diseases of the genitourinary system, etc. The presence of infectious and inflammatory diseases of the male reproductive system leads to impaired reproductive and endocrine function, significantly reducing the reproductive potential. In the last three years of our time around the world, including Russia, the number of people who have become ill with a new viral infection (COVID-19) caused by the new coronavirus (SARS-CoV-2), which causes dysfunction and has a negative effect on many organs and organs, body systems.The overview of recent publications is devoted to the study of the effect of SARS-CoV-2 on the reproductive health of men. The search was performed using the Medline, PubMed, and EMBASE databases

    Pathological findings in semen analysis from COVID-19 survivors and the impact of various SARS-COV-2 vaccines on spermatogenesis

    Get PDF
    Male reproductive health depends on many factors, including whether infectious diseases occur in the reproductive system. Such changes may be reflected in the semen analysis. In the past three years, the number of individuals who fell ill with COVID-19 caused by SARS-CoV-2 has been growing worldwide, including in Russia. This infection causes dysfunction and a negative effect on many organs and systems, including reproductive organs, which is reflected in abnormal semen parameters. Despite the high efficacy and small number of side effects found in clinical trials, only 56% of the population in the US and 49% in the Russian Federation reported wanting the vaccine. One of the reasons for distrust of vaccines is the potential negative impact on fertility. A literature review is devoted to the study of the effect of SARS-CoV-2 and vaccination on male reproductive health. The search was carried out using Medline, PubMed, and EMBASE databases

    Extended Thromboprophylaxis with Betrixaban in Acutely Ill Medical Patients

    Get PDF
    Background Patients with acute medical illnesses are at prolonged risk for venous thrombosis. However, the appropriate duration of thromboprophylaxis remains unknown. Methods Patients who were hospitalized for acute medical illnesses were randomly assigned to receive subcutaneous enoxaparin (at a dose of 40 mg once daily) for 10±4 days plus oral betrixaban placebo for 35 to 42 days or subcutaneous enoxaparin placebo for 10±4 days plus oral betrixaban (at a dose of 80 mg once daily) for 35 to 42 days. We performed sequential analyses in three prespecified, progressively inclusive cohorts: patients with an elevated d-dimer level (cohort 1), patients with an elevated d-dimer level or an age of at least 75 years (cohort 2), and all the enrolled patients (overall population cohort). The statistical analysis plan specified that if the between-group difference in any analysis in this sequence was not significant, the other analyses would be considered exploratory. The primary efficacy outcome was a composite of asymptomatic proximal deep-vein thrombosis and symptomatic venous thromboembolism. The principal safety outcome was major bleeding. Results A total of 7513 patients underwent randomization. In cohort 1, the primary efficacy outcome occurred in 6.9% of patients receiving betrixaban and 8.5% receiving enoxaparin (relative risk in the betrixaban group, 0.81; 95% confidence interval [CI], 0.65 to 1.00; P=0.054). The rates were 5.6% and 7.1%, respectively (relative risk, 0.80; 95% CI, 0.66 to 0.98; P=0.03) in cohort 2 and 5.3% and 7.0% (relative risk, 0.76; 95% CI, 0.63 to 0.92; P=0.006) in the overall population. (The last two analyses were considered to be exploratory owing to the result in cohort 1.) In the overall population, major bleeding occurred in 0.7% of the betrixaban group and 0.6% of the enoxaparin group (relative risk, 1.19; 95% CI, 0.67 to 2.12; P=0.55). Conclusions Among acutely ill medical patients with an elevated d-dimer level, there was no significant difference between extended-duration betrixaban and a standard regimen of enoxaparin in the prespecified primary efficacy outcome. However, prespecified exploratory analyses provided evidence suggesting a benefit for betrixaban in the two larger cohorts. (Funded by Portola Pharmaceuticals; APEX ClinicalTrials.gov number, NCT01583218. opens in new tab.

    Morphological changes in testicles of patients with idiopathic infertility after novel coronavirus infection (COVID-19)

    Get PDF
    Introduction. SARS-CoV-2 causes several negative processes in the body and complicates the course of chronic somatic diseases, causing dysfunction and having a negative effect on many organs and systems of the body, including organs of the reproductive system.Objective. To study morphological changes in testicles of patients who have undergone a new coronavirus infection.Materials and methods. Objects of morphological research were testicular tissues obtained by intraoperative biopsy under intravenous anesthesia served. Material sampling was carried out in 12 patients aged 25–29 years with idiopathic infertility who underwent COVID-19. Patients showed ultrasound signs of fibrosis in the testicles, which were absent before infection with SARS-CoV-2. The biopsy was performed 12 months after COVID-19.Results. In all observations, changes were observed that are characteristic of the inflammatory process, nonbacterial autoimmune genesis. Histio-lymphocytic infiltration of testicular tissue with destruction of single tubules and parenchyma atrophy, combined with varying degrees of sclerosis, was verified.Conclusion. In testicular biopsy specimens from patients who have undergone COVID-19, an autoimmune inflammatory process is recorded, manifested by lymphocytic infiltration of testicular tissue, which was combined with varying degrees of sclerosis

    At last, a Pennsylvanian stem-stonefly (Plecoptera) discovered

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Stem-relatives of many winged insect orders have been identified among Pennsylvanian fossils (Carboniferous Period). Owing to their presumed 'basal' position in insect phylogeny, stoneflies were expected to occur at this period. However, no relative has ever been designated convincingly.</p> <p>Results</p> <p>In this paper, we report specimens belonging to a new fossil insect species collected from the Tupo Formation (Pennsylvanian; China). The wing venation of <it>Gulou carpenteri </it><b>gen. et sp. nov</b>. exhibits character states diagnostic of the order Plecoptera, but lack character states shared by unequivocal representatives of the order. Derived from this identification, the delimitation of the fossil species is ascertained based on comparison of several extant stonefly species. This comparative analysis allowed a trait present in <it>G. carpenteri </it><b>gen. et sp. nov</b>., but rarely occurring in extant species, to be documented and highlighted as atavistic. Affinities of taxa formerly proposed as putative stem-stoneflies are reconsidered in the light of the new discovery.</p> <p>Conclusions</p> <p><it>Gulou carpenteri </it><b>gen. et sp. nov</b>. is considered the only genuine Plecoptera reported from the Pennsylvanian. Continuing efforts on the systematics of Pennsylvanian winged insects indicate a fauna more diverse than previously appreciated. It suggests that insects already had a long, yet undocumented, history by this time.</p
    corecore