41 research outputs found
XMM-Newton and Swift observations of WZ Sge: spectral and timing analysis
WZ Sagittae is the prototype object of a subclass of dwarf novae, with rare
and long (super)outbursts, in which a white dwarf primary accretes matter from
a low mass companion. High-energy observations offer the possibility of a
better understanding of the disk-accretion mechanism in WZ Sge-like binaries.
We used archival XMM-Newton and Swift data to characterize the X-ray spectral
and temporal properties of WZ Sge in quiescence. We performed a detailed timing
analysis of the simultaneous X-ray and UV light curves obtained with the EPIC
and OM instruments on board XMM-Newton in 2003. We employed several techniques
in this study, including a correlation study between the two curves. We also
performed an X-ray spectral analysis using the EPIC data, as well as Swift/XRT
data obtained in 2011. We find that the X-ray intensity is clearly modulated at
a period of about 28.96 s, confirming previously published preliminary results.
We find that the X-ray spectral shape of WZ Sge remains practically unchanged
between the XMM-Newton and Swift observations. However, after correcting for
inter-stellar absorption, the intrinsic luminosity is estimated to be about
2.65X10^ 30 erg/s/cm^2 and 1.57X10^30 erg/s/cm^2 in 2003 and 2011,
respectively. During the Swift/XRT observation, the observed flux is a factor
of about 2 lower than that observed by XMM-Newton, but is similar to the
quiescent levels observed various times before the 2001 outburst.Comment: Accepted for publication on A&A.10 pages, 9 figure
Dihydropyridinesâ metabolites-induced early apoptosis after myocardial infarction in rats; new outlook on preclinical study with M-2 and M-3
Cardiovascular and hormonal responses to static handgrip in young and older healthy men
The purpose of this study was to investigate the effect of age on cardiovascular changes and plasma concentrations of adrenomedullin (ADM), catecholamines, endothelin-1 (ET-1) and plasma renin activity (PRA) in healthy men. A total of 15 young (21 ± 0.3 years) and 15 older (64 ± 0.7 years) healthy men performed two 3-min bouts of static handgrip at 30% of maximal voluntary contraction, alternately with each hand without any break between the bouts. During exercise heart rate (HR), blood pressure (BP), stroke volume (SV) and pre-ejection period (PEP) and left ventricle ejection time (LVET) were measured. Blood samples were taken before exercise, at the end of both exercise bouts and in the fifth minute of the recovery period. The handgrip-induced increases in HR and cardiac output were significantly smaller in older than in young men (p < 0.01). SV decreased only in older men (p < 0.001). There were no differences between groups in BP increases. The baseline plasma ADM and catecholamines were higher in older man compared to young subjects. Handgrip caused increases in plasma ADM, ET-1 and PRA only in older men (p < 0.05). The increases in plasma ADM correlated positively with those of noradrenaline (NA), PRA, ET-1 and LVET and negatively with changes in total peripheral resistance (TPR), SV, PEP and PEP/LVET ratio. The increases in plasma ET-1 correlated positively with those of NA, PRA, TPR, mean BP and SV. These results revealed that ADM, ET-1 and angiotensin II can contribute to maintain vascular tone during static exercise in older but not in younger men
Structure and properties of diamond-like carbon films deposited by pacyd technique on light alloys
The investigations presented in this paper describe surface treatment performed on samples of heat-treated cast magnesium and aluminium alloy. The structure and chemical composition as well as the functional and mechanical properties of the obtained gradient/monolithic films were analysed by high resolution transmission electron microscopy and scanning electron microscopy, Raman spectroscopy, die ball-on-disk tribotester and scratch testing. Moreover, investigation of the electrochemical corrosion behaviour of the samples was carried out by means of potentiodynamic polarisation curves in 1-M NaCl solution. The coatings produced by chemical vapour deposition did not reveal any delamination or defects and they adhere closely to the substrate. The coating thickness was in a range of up to 2.5 microns. Investigations using Raman spectra of the DLC films confirmed a multiphase character of the diamond-like carbon layer, revealing the sp and sp3 electron hybridisation responsible for both the hardness and the friction coefficient. The best wear resistance test results were obtained for the magnesium alloy substrate - AZ61, for which the measured value of the friction path length was equal to 630 m
Obtaining of biomorphic composites based on carbon materials
Aim of this paper is to present the properties of carbon preforms for the production of biomorphic composites. Carbon samples were obtained through pyrolysis of paulownia wood, replicating the microstructure of the cellulosic precursor. Many characterization methods such as Raman Spectroscopy, light microscopy, hardness tests and pore size analyzer detection were used to investigate the microstructure of the product as well as the pore size of carbon samples. Obtained results showed that the parts of early or late wood template play an important role in the pore size, specific surface area and pore volume of the product. This review aims to be a comprehensive description of the development of carbon chars: from wood templates and their microstructure to potential applications of biomorphic materials
The Taxonomy of Selected Genera of the Subfamily Limoniinae (Diptera: Limoniidae) from Baltic Amber (Eocene), with Notes on Their Phylogeny
Relation between expression of TNF alpha, iNOS, VEGF mRNA and development of heart failure after experimental myocardial infarction in rats
Collective Narcissism and Anti-Semitism in Poland: the Mediating Role of Siege Beliefs and the Conspiracy Stereotype of Jews
Two studies examined the relationship between collective narcissism - an emotional
investment in an unrealistic belief about unparalleled greatness of an in-group (Golec de
Zavala et al., 2009) - and anti-Semitism in Poland. The results indicate that this relationship is
simultaneously mediated by (a) a belief that the in-group is constantly threatened by hostile
intentions of other groups (Polish siege beliefs; Bar-Tal & Antebi, 1992) and (b) a belief that
the Jewish out-group is particularly threatening because its members secretly aim to dominate
the world (the conspiracy stereotype of Jews; Bergmann, 2008; Kofta & S?dek, 2005). The
results confirm earlier findings that collective narcissism is linked to increased sensitivity to
intergroup threat which drives its association with intergroup hostility. The sensitivity to
intergroup threat is composed of beliefs about vulnerability of the in-group and hostility of the
out-group