49 research outputs found
TeV neutrinos from microquasars in compact massive binaries
We consider a compact binary system in which a Wolf-Rayet star supplies
matter onto a stellar mass black hole or a neutron star. This matter forms an
accretion disk which ejects a jet as observed in Galactic microquasars. A part
of the jet kinetic energy, typically 10%, can be transfered to relativistic
nuclei. These nuclei lose nucleons as a result of photo-disintegration process
in collisions with thermal photons from the accretion disk and the massive
star. Due to the head on photon-nucleus collisions most of neutrons released
from nuclei move towards the surface of the accretion disk and/or the massive
star producing neutrinos in collisions with the matter. We calculate the
spectra of muon neutrinos and expected neutrino event rates in a 1 km^2
neutrino detector of the IceCube type from a microquasar inside our Galaxy
applying, as an example, the parameters of the Cyg X-3 binary system, provided
that nuclei are accelerated to the Lorentz factors above 10^6 with the power
law spectrum with an index close to 2.Comment: 13 pages, 2 figures, ApJ, accepte
TeV neutrinos from accreting X-ray pulsars
Pulsars inside binary systems can accrete matter that arrives up to the
pulsar surface provided that its period is long enough. During the accretion
process, matter has to be accelerated to the rotational velocity of the pulsar
magnetosphere at the distance where the balance between the pressure of matter
and the magnetic field is achieved. At this distance, a very turbulent and
magnetized region is formed in which hadrons can be accelerated to relativistic
energies. These hadrons can interact with the very strong radiation field
coming from the hot polar cap on the neutron star surface created by the
in-falling matter. We calculate the neutrino event rates produced in an km
detector that can be expected from accreting millisecond and classical X-ray
pulsars at a typical distance within our own Galaxy.Comment: 5 pages, accepted to Physical Review
The Effects of Cocaine on Different Redox Forms of Cysteine and Homocysteine, and on Labile, Reduced Sulfur in the Rat Plasma Following Active versus Passive Drug Injections
Received: 28 November 2012 / Revised: 19 April 2013 / Accepted: 6 May 2013 / Published online: 16 May 2013
The Author(s) 2013. This article is published with open access at Springerlink.comThe aim of the present studies was to evaluate
cocaine-induced changes in the concentrations of different
redox forms of cysteine (Cys) and homocysteine (Hcy),
and products of anaerobic Cys metabolism, i.e., labile,
reduced sulfur (LS) in the rat plasma. The above-mentioned
parameters were determined after i.p. acute and
subchronic cocaine treatment as well as following i.v.
cocaine self-administration using the yoked procedure.
Additionally, Cys, Hcy, and LS levels were measured
during the 10-day extinction training in rats that underwent
i.v. cocaine administration. Acute i.p. cocaine treatment
increased the total and protein-bound Hcy contents,
decreased LS, and did not change the concentrations of Cys
fractions in the rat plasma. In turn, subchronic i.p. cocaine administration significantly increased free Hcy and lowered
the total and protein-bound Cys concentrations while
LS level was unchanged. Cocaine self-administration
enhanced the total and protein-bound Hcy levels, decreased
LS content, and did not affect the Cys fractions. On the
other hand, yoked cocaine infusions did not alter the concentration
of Hcy fractions while decreased the total and
protein-bound Cys and LS content. This extinction training
resulted in the lack of changes in the examined parameters
in rats with a history of cocaine self-administration while in
the yoked cocaine group an increase in the plasma free Cys
fraction and LS was seen. Our results demonstrate for the
first time that cocaine does evoke significant changes in
homeostasis of thiol amino acids Cys and Hcy, and in some
products of anaerobic Cys metabolism, which are dependent
on the way of cocaine administration
Exploiting structure similarity in refinement: automated NCS and target-structure restraints in BUSTER
Local structural similarity restraints (LSSR) provide a novel method for exploiting NCS or structural similarity to an external target structure. Two examples are given where BUSTER re-refinement of PDB entries with LSSR produces marked improvements, enabling further structural features to be modelled
Some physical properties of soil and yielding of crops grown with different forms of mulching and tillage
Celem badań było określenie wpływu stosowania zróżnicowanej uprawy roli i pożniwnego zagospodarowania słomy na niektóre właściwości fizyczne gleby i plonowanie roślin. Przy umiarkowanym niedoborze opadów, niezależnie od gospodarki słomą, istotnie niższe plony wydawały rośliny uprawiane systemem zerowym. W takich samych warunkach pogodowych, niezależnie od wariantów uprawowych, najniższe plony powodowało usuwanie słomy i nie stosowanie międzyplonu. W warunkach silnego niedoboru opadów poziom plonów był niski i na zmianę tego efektu nie miał znaczącego wpływu żaden z testowanych wariantów doświadczenia.The research aimed at assessing the influence of differentiated tillage and post-harvest straw management on some physical properties of soil and yielding of crop. The yielding of crops was differentiated; under moderate deficit of precipitation, irrespective of straw management, significantly lower yields were obtained of crops grown with zero system. Under similar weather conditions, irrespective of tillage system, the lowest yields were obtained when straw had been removed and no intercrop grown. Under strong deficiency of precipitation the yields were very low, that effect having been not changed significantly by any of the experimental variants tested
Combined heat and power systems in liquefied natural gas (LNG) regasification processes
Adaptation of liquefied natural gas (LNG) to the quality requirements for natural gas transportation pipeline system is a high energy intensive process. The energy for this process can be obtained include from waste heat in the industry processes, steam power blocks or sea water in LNG unloading terminal. Another way of obtaining the heat is burning of gas or other fuels. A large temperature difference between the heat sources in each of these cases, and the low temperature of LNG can be used to control of the pumping engine operation, it can pro vi de optimization and reduction of the costs. Liquefied natural gas (LNG) can be used as a source of cold to the increasing power of the cogeneration process. The article examines some practical cogeneration solutions (combined heat and called power - CHP), which can improve the efficiency of the process of regasification of LNG