Off-equatorial orbits in strong gravitational fields near compact objects

Near a black hole or an ultracompact star, motion of particles is governed by strong gravitational field. Electrically charged particles feel also electromagnetic force arising due to currents inside the star or plasma circling around. We study a possibility that the interplay between gravitational and electromagnetic action may allow for stable, energetically bound off-equatorial motion of charged particles. This would represent well-known generalized Stormer's 'halo' orbits, which have been discussed in connection with the motion of dust grains in planetary magnetospheres. We demonstrate that such orbits exist and can be astrophysically relevant when a compact star or a black hole is endowed with a dipole-type magnetic field. In the case of Kerr-Newman solution, numerical analysis shows that the mutually connected gravitational and electromagnetic fields do not allow existence of stable halo orbits above the outer horizon of black holes. Such orbits are either hidden under the inner black-hole horizon, or they require the presence of a naked singularity.Comment: 16 pages, 7 figures, accepted in Class. Quantum Grav. (2008

Některé aspekty Stroemerova problému v silných gravitačních polích

We study halo orbits in strong gravitational fields

ATLAS Distributed Computing Monitoring tools after full 2 years of LHC data taking

This paper details variety of Monitoring tools used within the ATLAS Distributed Computing during the first 2 years of LHC data taking. We discuss tools used to monitor data processing from the very first steps performed at the Tier-0 facility at CERN after data is read out of the ATLAS detector, through data transfers to the ATLAS computing centers distributed world-wide. We present an overview of monitoring tools used daily to track ATLAS Distributed Computing activities ranging from network performance and data transfers throughput, through data processing and readiness of the computing services at the ATLAS computing centers, to the reliability and usability of the ATLAS computing centers. Described tools provide monitoring for issues of different level of criticality: from spotting issues with the instant online monitoring to the long-term accounting information

Preliminary insights into the impact of dietary starch on the ciliate, Neobalantidium coli, in captive chimpanzees.

Infections caused by the intestinal ciliate Neobalantidium coli are asymptomatic in most hosts. In humans and captive African great apes clinical infections occasionally occur, manifested mainly by dysentery; however, factors responsible for development of clinical balantidiasis have not been fully clarified. We studied the effect of dietary starch on the intensities of infection by N. coli in two groups of captive chimpanzees. Adult chimpanzees infected by N. coli from the Hodonín Zoo and from the Brno Zoo, Czech Republic, were fed with a high starch diet (HSD) (average 14.7% of starch) for 14 days, followed by a five-day transition period and subsequently with a period of low starch diet (LoSD) (average 0.1% of starch) for another 14 days. We collected fecal samples during the last seven days of HSD and LoSD and fixed them in 10% formalin. We quantified trophozoites of N. coli using the FLOTAC method. The numbers of N. coli trophozoites were higher during the HSD (mean ± SD: 49.0 ± 134.7) than during the LoSD (3.5 ± 6.8). A generalized linear mixed-effects model revealed significantly lower numbers of the N. coli trophozoites in the feces during the LoSD period in comparison to the HSD period (treatment contrast LoSD vs. HSD: 2.7 ± 0.06 (SE), z = 47.7; p<<0.001). We conclude that our data provide a first indication that starch-rich diet might be responsible for high intensities of infection of N. coli in captive individuals and might predispose them for clinically manifested balantidiasis. We discuss the potential nutritional modifications to host diets that can be implemented in part to control N. coli infections

ATLAS Distributed Computing Operation Shift Teams experience during the discovery year and beginning of the Long Shutdown 1

Poster : ATLAS Distributed Computing Operation Shift Teams experience during the discovery year and beginning of the Long Shutdown 1

Numbers of <i>Neobalantidium coli</i> in chimpanzee feces during low-starch (LoSD) and high-starch (HSD) diets in two study groups.

<p>Numbers of <i>Neobalantidium coli</i> in chimpanzee feces during low-starch (LoSD) and high-starch (HSD) diets in two study groups.</p

Daily intake of experimental diets fed to chimpanzees (means of wet matter, g/day and chimpanzee).

<p>HSD – high starch diet; LoSD – low starch diet. ¹Zoo Hodonín: orange, grapes, apple, pineapple, banana, kiwi, pears, watermelon, plum, nectarine; ¹Zoo Brno: orange, grapes, apple, pineapple, banana, kiwi; ²both zoos: pepper, tomato, carrot, kohlrabi, cucumber; ³Zoo Hodonín: onion, leek, cauliflower, beet, spring onion, lettuce, Chinese leaves, nectarine; ³Zoo Brno: onion, leek, cauliflower, beet, lettuce, Chinese leaves.</p

ATLAS Distributed Computing Shift Operation in the first 2 full years of LHC data taking

ATLAS Distributed Computing organized 3 teams to support data processing at Tier-0 facility at CERN, data reprocessing, data management operations, Monte Carlo simulation production, and physics analysis at the ATLAS computing centers located world-wide. In this paper we describe how these teams ensure that the ATLAS experiment data is delivered to the ATLAS physicists in a timely manner in the glamorous era of the LHC data taking. We describe experience with ways how to improve degraded service performance, we detail on the Distributed Analysis support over the exciting period of the computing model evolution