Modern studies on the Be star population of young open clusters point towards the presence of an evolutionary enhancement of the Be phenomenon in the second half of the B stars main sequence lifetime. However, in the galactic field, Be stars are equally present in luminosity classes V to III, indicating that there is no evolutionary trend. To investigate these diverging results we have studied samples of main sequence B stars in the galactic field and in theh and ¬ Per clusters. From the analysis of the HR diagrams it is shown that there is no segregation between class V and class III stars, both groups being evenly distributed along the whole main sequence. We conclude that luminosity classes of main sequence B stars are not related to the evolutionary status of the stars. We propose a scenario of evolutionary enhancement of the rotational velocity to explain both the lack of relation between the evolutionary status and the luminosity classes and the evolutionary enhancement of the Be phenomenon.
This paper deals with an experimental study of lubricant film in an experimental device (tribometer). Lubricating film is formed between a glass disc and steel ball on which modification for friction surfaces have been made. The experiment is aimed at both fully flooded EHL lubrication regime as well as the starved. This document also deals with a comparison of micro dents passage through a contact at different degrees of slip. and Obsahuje seznam literatury
This paper considers an exponential cost optimality problem for finite horizon semi-Markov decision processes (SMDPs). The objective is to calculate an optimal policy with minimal exponential costs over the full set of policies in a finite horizon. First, under the standard regular and compact-continuity conditions, we establish the optimality equation, prove that the value function is the unique solution of the optimality equation and the existence of an optimal policy by using the minimum nonnegative solution approach. Second, we establish a new value iteration algorithm to calculate both the value function and the ϵ-optimal policy. Finally, we give a computable machine maintenance system to illustrate the convergence of the algorithm.
In the present study we investigated the effect of a two-stage bilateral lesion of the olfactory bulb (OB) in rats on the regeneration ability of peripheral olfactory neurons and their reinnervation capacity in the spared OB. The outgrowth of newly-generated olfactory axons as well as the maturation of their terminal synaptic field was detected by immunohistochemistry of the growth-associated phosphoprotein B-50/GAP-43. In addition, the glial response to the surgery was monitored by an immunohistochemical marker for astrocytes, glial fibrillary acidic protein (GFAP). In neonatal rats (P3-P5), the right OB was removed, then three months later the contralateral side was ablated. Six days after the second operation the animals were transcardially perfused. Their brains were embedded in paraplast, serially sectioned and processed for histological and immunohistochemical observations. After neonatal OB ablation, homogeneous B-50-immunoreactivity (BIR) was found in the forebrain, olfactory axons and ectopic glomeruli localized in the small OB remnant-like structures and in the regenerated neuroepithelium. A strong GFAP response was revealed in the brain cortex as well as in the newly-formed olfactory axons and glomeruli-like structures of the OB remnants. After adult OB ablation strong BIR was observed in olfactory axons, while remaining glomerular structures were only faintly stained. The neuroepithelium revealed signs of massive degenerative processes with a substantial decrease in BIR. The GFAP-positive astrocytes were scattered throughout the entire OB remnant and were prominent in the glomeruli-like structures and adjacent frontal cortex. In the present study, we applied GAP-43 and GFAP immunohistochemistry to characterize the responses of individual olfactory components after two-stage olfactory bulbectomy. Furthermore, this model of OB ablation characterized by two immunohistochemical markers could elucidate certain molecular mechanisms involved in the regeneration and/or plasticity of the olfactory system.
The host immune response to parasitic infections plays an important role in controlling multiplication of the parasite and reducing clinical symptoms and life-threatening complications. Nitric oxide (NO), an important innate immune factor and classic Th1 immune effector, may play a role in inhibiting plasmodium infection. In this study, we used two different approaches (L-Arginine [precursor of NO] and NOC5 [short-time NO donor]) to prove the roles of NO in malaria infection. We used 6-8 week-old female BALB/c mice infected with the rodent malaria Plasmodium yoelii Landau, Michel et Adam, 1968 - strain 17XL (P.y17XL) - as a model. For L-Arg treatment, mice were administered with an oral dose of 1.5 mg/g L-Arg daily for seven consecutive days prior to infection with P.y17XL. L-Arg pretreatment resulted in the decrease of the mRNA level of the apical membrane antigen 1 (AMA1) gene, which encodes a protein involved in host invasion. For NOC5 treatment, NOC5 was injected intraperitoneally into the P.y17XL infected mice on day 5 post-infection or incubated in vitro with purified P.y17XL schizonts. Both in vivo and in vitro treatments with NOC5 led to down-regulation of the transcript and protein levels of invasion-related molecules (AMA1, merozoites surface protein 1 and Py235). Our results confirmed the protective role of NO in the asexual blood stage of parasitic infection, which may be partially due to reduced expression of parasite invasion molecules.
Throughout most of the distributional range, the fat dormouse, Glis glis, relies heavily upon European beech as a key species in its habitat. In Lithuania however, situated beyond the continuous range of the beech, pedunculate oak becomes the essential tree in habitats of G. glis. In Lithuania, the dormouse activity season lasts from mid-May to mid-October, young are born during the short period from late July to mid-August, and the mean litter size is 5.9 young. Population density is low (0.8-2.0 ind./ha after hibernation and 1.2-4.8 ind./ha in autumn), but relatively stable. The mean body weights of adults (98 g after hibernation and 128 g before hibernation) are among the lowest across the range. Lithuanian dormice differ from those living in beech-dominated habitats by their lower population density and lower body weight. Such differences may be due to acorns being less suitable food for G. glis in comparison to beech nuts. In terms of inter-annual abundance dynamics, the G. glis population is comparatively stable as years in which dormice fail to reproduce are infrequent in Lithuania.
The fatty acid composition is associated with obesity. Omega 3 polyunsaturated fatty acid (PUFA) could have a beneficial role in the prevention and treatment of many disorders, including cardiometabolic diseases. A cohort of 84 men and 131 women were examined in adolescence and after 8 years. Body weight (BW) and fat mass (FM) were measured. The composition of fatty acids (FAs) of serum phospholipids was assessed using gas chromatography. Statistics: PLS method. Aim: to determine the relationships between FAs in adolescence and FM (explanatory variable 1, EV1) and BW (explanatory variable 2, EV2) in adulthood. In the predictive models, a cluster of FAs in boys explained 47.2 % of EV1 and a cluster of 6 FAs in girls explained 32.3 % of EV1 measured in adulthood. FAs measured in adolescents explained 23.7 % of EV2 in early adults regardless of gender. A significant negative association was found between 18:1n-9c and EV1 in males and EV2 in both genders. We found a significant negative association between 18:2n-6 and 20:0 and both EV1 and EV2. In all analyses, we found a significant negative association of 20:1n-9 and 18:3n-3 with EV1-2 in both genders. A significant positive association was found in 20:3n-6 with EV1 and EV2 in males. 20:4n-6 was positively associated with EV1 in females and EV2 in both genders. A positive association between FM and very long chain n- 6 PUFAs was also observed. It is concluded that serum MUFAs and essential PUFAs in adolescence are associated with lower BW and FM in adulthood.
Two new species of feather mites are described from nightjars (Caprimulgiformes: Caprimulgidae) of Brazil: Hartingiella neotropica sp. n. (Xolalgidae) described from Hydropsalis parvula (Gould) and Paragabucinia brasiliensis sp. n. (Gabuciniidae) from H. albicollis (Gmelin). The former differs from the type species by having, in males, the anterior projections on epimerites III towards setae 3b and the adanal shield bearing setae ps3 present; in both sexes, a pair of small sclerites situated posterior to setae se have flat suprategumental processes. Paragabucinia brasiliensis sp. n. differs from P. petitoti (Gaud et Mouchet, 1959) by the smaller size of the incisions in the internal margins of opisthosomal lobes of males. These mites are the first representatives of corresponding genera described from the Neotropical region. The genus Hartingiella Gaud, 1980 was previously known solely from its type species. Keys to males and females of the genus Paragabucinia Gaud et Atyeo, 1975 are presented. In addition, all previous records of feather mites associated with birds of the order Caprimulgiformes of the world are summarised.