According to modern theories, the parameters of neutral mesons such as their mass and width are closely connected with the medium in which the mesons are present. Experimental data on the study of ...mesons in a nuclear medium are in demand for development of theoretical models describing processes in the field of nonperturbative quantum chromodynamics (QCD). Masses and widths of neutral mesons produced in meson-nucleus interactions on various nuclei are measured in the Hyperon-M experiment at the U70 accelerator. The paper describes a method for precision measurement of the parameters of neutral mesons, presents the results on measurement of the mass and width of the
meson and preliminary results on the measurement of the mass and width of the
meson. The measurements indicate the absence of dependence of the quantities under study on the nuclear environment.
In this investigation we assessed the physiological reaction of hamsters in response to chemical signals from potential sexual partners, and also after a private meeting with them, which allowed us ...to ascertain the type of mating system for this species. The reception of olfactory signals led to an increase in peroxidase activity in the blood for both sexes, indicative of activity of a non-specific line of immune defense in recipients. The increase in blood cortisol level in response to the chemical signals of a partner was only observed in females. Males spent more time near samples of estrous females, with elevated levels of cortisol in the urine. In olfactory tests, an hour after grouping all the individuals in pairs there was a significant increase in blood peroxidase activity, which indicates the reaction of a non-specific link in the immune system of partners. This increase was greater in the pairs with a mutual preference. Females from these pairs demonstrated a substantial decrease in stress hormone levels in the plasma after an hour of mating in comparison to females prior to mating, and in non-preferred coupling.
An experiment aimed at revealing the consequences of adding two species of entomopathogenic Ascomycetes,
Beauveria bassiana
and
Metarhizium robertsii
, to grain fodder showed that northern red-backed ...voles that received
M. robertsii
conidia in their food for 15 days had higher levels of triglycerides, glucose, and peroxidase in the blood; differed from other animals in social behavior patterns; and demonstrated significantly less emotionality in an open field test than control animals. The voles fed fungal conidia showed a trend towards reduced survival in captivity compared to controls. These data indicate the significant impact of entomopathogenic fungi on the metabolism, behavior, and lifespan of nontarget mammals.
The modification of the spectral function of vector mesons in nuclear matter is predicted in many theoretical models. However, the existing experimental results for testing these models are ...contradictory. Possible effects of the modification of the mass and width of ω mesons produced in the collisions of 7-GeV/
c
positively charged mesons with C, Be, Al, Cu, Sn, and Pb nuclear targets have been sought in the Hyperon-M experiment. The measured mass and width of ω mesons produced on the indicated nuclei are in agreement with each other with a high accuracy, which does not confirm the theoretical models predicting modification of the mass and/or width of the ω meson in nuclear matter.
Abstact
—The paper presents the upgrade project of the Hyperon-M experiment in the positive beam line of the U-70 accelerator complex in Protvino to study hadron-nuclear interaction mechanisms. It is ...proposed that the setup be upgraded to study the excited states of secondary nuclei formed by different types of primary hadron–nuclear interaction using precision nuclear gamma-ray spectroscopy. This could open a new direction of the nuclear physics at the junction with the physics of elementary particles at intermediate energies.
Reliability and cost-effectiveness are the main requirements for aircraft materials and structure components used in manufacturing of aviation engines. This defines the requirements for them. The ...majority of components are thin-walled and made of hard-to-machine materials: nickel and titanium alloys, heat-resistant steels. The use of such materials places restrictions on the use of certain cutting modes. During rough milling and semi-finish milling with end-mill cutters chatter occur. The vibrations deteriorate the machined surface of engine parts, tool life decreases and machine units are worn out. Different process technologies and constructive features of tools are used to decrease the intensity of chatter. The use of end mills having lands has yielded mixed results. The influence of land usage on surface condition and decrease of chatter in up-milling and down milling has been studied. The mechanism of influence on machined surface and chatter in up-milling and down milling has been determined. At the experimental stand studies were carried out on its effect on changes in the laws of motion of detail during the cutting process. It has been shown that in up-milling and down milling, a land fl = 0.05 mm wide on the rear surface along the cutting tooth reduces the intensity of chatter has been shown. The results can be used to select the feed direction to reduce the intensity of chatter when milling thin-walled parts with end mills with a land on the rear surface along the cutting edges.
Eusocial subterranean rodents of the Bathyergidae family have enormous longevity. The long lifespan of these species is associated with negligible senescence, that is, an absence of the signs of ...age-related deterioration in physical condition. The question arises as to whether these features are unique to eusocial Bathyergids or typical of other social subterranean rodents as well. In the present study, we analysed data from observations of a social subterranean Microtinae rodent, the northern mole vole (
Ellobius talpinus
Pall.), which, like mole-rats, has reproductive skew. Among the individuals captured in the wild and maintained in captivity, females that reproduced lived significantly longer than non-breeding females. We did not find any changes in muscle strength with age in any of the demographic groups studied. Faecal glucocorticoid concentrations before death were significantly higher in non-breeding females than in breeding females and males. Increased adrenocortical activity may be one mechanism responsible for the decreased lifespan of non-reproducing individuals of social subterranean rodents. We conclude that the patterns of aging, although different in some respects, are generally common for social subterranean rodents of different taxonomic groups.
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To test the hypothesis that animals from habitats exposed to high anthropogenic pressure are more successful in adapting to captivity, immature narrow-skulled voles trapped in different zones of ...Karasuk Research Station (Institute of Systematics and Ecology of Animals) and beyond its boundaries were kept under laboratory conditions. Voles trapped in the immediate vicinity of service and living buildings rapidly gained weight, but their mortality rate was higher than in voles trapped at the periphery of the station or beyond its territory. The highest survival rate was observed among voles from the periphery of the station, which were especially shy and socially affiliative. Thus, narrow-skulled voles born and grown under high anthropogenic pressure proved to adapt to captivity more easily, but their survival rate was lower than in voles from habitats exposed to moderate or weak anthropogenic pressure.
To test the hypothesis of relationship between the age at maturity, metabolic rate, and life span of rodents, variation in bioenergetic parameters in northern red-backed voles (Myodes rutilus) was ...analyzed depending on their reproductive status and type of ontogeny. Standard metabolic rate was found to be significantly lower in young of the year that remained nonreproductive in the year of birth than in reproductive young of the year and overwintered voles. Maximal metabolic rate and the ability to maintain temperature homeostasis under cold exposure were independent of reproductive status and life history pattern but varied depending on phases of the population cycle, increasing in years with low animal abundance.
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