598 research outputs found
Study of the island morphology at the early stages of Fe/Mo(110) MBE growth
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
New coronavirus disease 2019 (COVID-19): Is there an impact on male reproductive health
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
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
Morphological changes in testicles of patients with idiopathic infertility after novel coronavirus infection (COVID-19)
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 25â29 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
Enhanced low-energy -decay strength of Ni and its robustness within the shell model
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 -emission
probability at very low energies. In this work, we present
measurements of the -decay strength of Ni over the wide range
MeV. A significant enhancement is found in the
-decay strength for transitions with 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
-strength calculations within the quasiparticle time-blocking
approximation, which describe our data above MeV very well.
Moreover, large-scale shell-model calculations indicate an nature of the
low-energy 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 .Comment: 9 pages, 9 figure
At last, a Pennsylvanian stem-stonefly (Plecoptera) discovered
<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
Networks, space and organisational performance:a study of the determinants of industrial research income generation by universities
This paper examines the extent to which both network structure and spatial factors impact on the organizational performance of universities as measured by the generation of industrial research income. Drawing on data concerning the interactions of universities in the UK with large research and development (R&D)-intensive firms, the paper employs both social network analysis and regression analysis. It is found that the structural position of a university within networks with large R&D-intensive firms is significantly associated with the level of research income gained from industry. Spatial factors, on the other hand, are not found to be clearly associated with performance, suggesting that universities operate on a level playing field across regional environments once other factors are controlled for
Recent growth coherence in long-term oak (Quercus spp.) ring width chronologies in the Czech Republic
Oak ring width measurements compiled from 44 sampling sites throughout the territory of the Czech Republic are analysed for the 1655-2013 period. Measurements taken at all these sites are sorted into 10 sub-chronologies on the basis of 5 environmental factors: soil moisture (dry/wet), elevation (low/high), age (young/old), species (Quercus robur or Q. petraea), and geographical position (east/west). Several statistical tests are applied to investigate existing significant differences between chronologies during 1920-2013. Further, the sensitivities of individual sub-chronologies to precipitation are compared. Three tests indicate 5 pairs of very similar sub-chronologies. Moreover, the growth-response to May-July precipitation totals is very much the same in these sub-chronologies. This analysis demonstrates that, even in the absence of certainty about age structure, species composition and some environmental factors in the earlier parts of oak ring width chronologies, the internal homogeneity of the chronology remains essentially unaffected, and the lack of such information does not preclude their use in dendroclimatology
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