528 research outputs found
Evolution of galaxy groups in the Illustris simulation
We present the first study of evolution of galaxy groups in the Illustris
simulation. We focus on dynamically relaxed and unrelaxed galaxy groups
representing dynamically evolved and evolving galaxy systems, respectively. The
evolutionary state of a group is probed from its luminosity gap and separation
between the brightest group galaxy and the center of mass of the group members.
We find that the Illustris simulation, over-produces large luminosity gap
galaxy systems, known as fossil systems, in comparison to observations and the
probed semi-analytical predictions. However, this simulation is equally
successful in recovering the correlation between luminosity gap and luminosity
centroid offset, in comparison to the probed semi-analytic model. We find
evolutionary tracks based on luminosity gap which indicate that a large
luminosity gap group is rooted in a small luminosity gap group, regardless of
the position of the brightest group galaxy within the halo. This simulation
helps, for the first time, to explore the black hole mass and its accretion
rate in galaxy groups. For a given stellar mass of the brightest group
galaxies, the black hole mass is larger in dynamically relaxed groups with a
lower rate of mass accretion. We find this consistent with the latest
observational studies of the radio activities in the brightest group galaxies
in fossil groups. We also find that the IGM in dynamically evolved groups is
hotter for a given halo mass than that in evolving groups, again consistent
with earlier observational studies.Comment: 10 pages, 10 figures. Accepted for publication in Ap
Epizootiološko istraživanje slinavke i šapa u Sudanu: stanje nakon dva desetljeća
In order to update information on the situation regarding foot and mouth disease (FMD) in the Sudan, a serosurvey and disease survey were conducted. Recently collected data on FMD in the Sudan showed that FMD is a major constraint to animal production in the country. It presents no threat nor does it cause mild disease in sheep and goats. The disease, with obvious clinical signs, has been detected in cattle only, and is caused by serotype O and SAT 2. Seasonal occurrence of the disease in the cold, dry season has been observed and animal
movement seems to play a major role in virus dissemination. A total of 1,069 sera were collected from cattle, sheep, goats, and camel, from seven states in the Sudan, for the detection of antibodies to FMDV. Application of liquid phase blocking (LPB) ELISA revealed that antibodies to four serotypes were present in ruminants; namely O, A, SAT 1 and SAT 2. No antibodies to FMDV were detected in camel sera. The results differed from early reports regarding the prevalence of serotype specifi c antibodies in different species; for instance, in cattle, the antibodies to type A (78.13%) surpassed that of type O (69.39%) and the antibodies to type SAT 2 (44%) surpassed that of type SAT 1 (20.2%). This work elucidates the current epidemiology of FMD in some parts of the Sudan.Radi pružanja informacija o sadašnjem stanju slinavke i šapa u Sudanu provedena su serološka istraživanja te je prikazana njezina pojavnost. Svježe prikupljeni podatci o pojavi slinavke i šapa u Sudanu pokazali su da ona predstavlja veliku prepreku životinjskoj proizvodnji u toj zemlji. U ovaca i koza javlja se kao blaga bolest i ne predstavlja veliku prijetnju, dok se u goveda javlja s očitim kliničkim znakovima, a uzrokovana je serotipovima O i SAT 2. Bolest se javlja sezonski u hladnoj i suhoj sezoni, a promet životinjama ima glavnu ulogu u širenju virusa. Ukupno je bilo prikupljeno 1069 uzoraka seruma goveda, ovaca, koza i deva podrijetlom iz sedam država u Sudanu radi pretrage na prisutnost protutijela za virus slinavke i šapa. Blokirajućim imunonenzimnim testom dokazana su protutijela za četiri serotipa virusa: O, A, SAT 1 i SAT 2. Protutijela za virus slinavke i šapa
nisu bila dokazana u uzorcima seruma deva. Rezultati se razlikuju od ranijih izvješća s obzirom na prevalenciju specifi čnih protutijela u različitih vrsta. Npr., specifi čna protutijela za serotip A dokazana su u 78,13% goveda, za serotip O u 69,39%, serotip SAT 2 u 44% te serotip SAT 1 u 20,2% goveda. U radu je prikazano sadašnje epizootiološko stanje slinavke i šapa u nekim dijelovima Sudana
Gas storage using fullerene based adsorbents
This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor
Self-Consistent Random Phase Approximation - Application to the Hubbard Model for finite number of sites
Within the 1D Hubbard model linear closed chains with various numbers of
sites are considered in Self Consistent Random Phase Approximation (SCRPA).
Excellent results with a minimal numerical effort are obtained for 2+4n sites
cases, confirming earlier results with this theory for other models. However,
the 4n sites cases need further considerations. SCRPA solves the two sites
problem exactly. It therefore contains the two electrons and high density Fermi
gas limits correctly.Comment: 17 pages, 17 figure
On the Reliability of Photometric and Spectroscopic Tracers of Halo Relaxation
We characterize the relaxation state of galaxy systems by providing an assessment of the reliability of the photometric and spectroscopic probe via the semianalytic galaxy evolution model. We quantify the correlations between the dynamical age of simuglated galaxy groups and popular proxies of halo relaxation in observation, which are mainly either spectroscopic or photometric. We find the photometric indicators demonstrate a stronger correlation with the dynamical relaxation of galaxy groups compared to the spectroscopic probes. We take advantage of the Anderson Darling statistic (A(2)) and the velocity segregation (Delta V) as our spectroscopic indicators, and use the luminosity gap (Delta m(12)) and the luminosity decentering (D-offset) as photometric ones. First, we find that a combination of Delta m(12) and D-offset evaluated by a bivariant relation (B = 0.04 x Delta m(12) - 0.11 x Log(Doff-set) + 0.28) shows a good correlation with the dynamical age compared to all other indicators. Second, by using the observational X-ray surface brightness map, we show that the bivariant relation brings about some acceptable correlations with X-ray proxies. These correlations are as well as the correlations between A(2) and X-ray proxies, offering a reliable yet fast and economical method of quantifying the relaxation of galaxy systems. This study demonstrates that using photometric data to determine the relaxation status of a group will lead to some promising results that are comparable with the more expensive spectroscopic counterpart.Peer reviewe
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