515 research outputs found
Shakhbazian compact galaxy groups. II. Photometric and spectroscopic study of ShCG 376
The results of the redshift measurements and of the detailed surface
photometry in BVR of the compact group ShCG 376 are presented. The radial
velocity dispersion, the virial mass, the total luminosity, the M/L ratio, and
the crossing time of the group are estimated. The group consists of eight
accordant redshift spiral galaxies. Four (or possibly five) of the group
members have emission-line spectra. Such morphological content and the number
of emission-line galaxies are very atypical for compact galaxy groups. There
are signs of interaction between some members of the group. It is suggested
that the irregular shape of the brightest galaxy No. 4 is probably due to
interaction with other members of the group, particularly, the emission line
galaxy No. 6 with a discordant redshift (Delta v = 2600 km/s). It is speculated
that the latter galaxy may be a infalling intruder to the group.Comment: accepted A&A, 7 pages, 6 figures are in separate file
Non-Markovian decoherence in the adiabatic quantum search algorithm
We consider an adiabatic quantum algorithm (Grover's search routine) weakly
coupled to a rather general environment, i.e., without using the Markov
approximation. Markovian errors generally require high-energy excitations (of
the reservoir) and tend to destroy the scalability of the adiabatic quantum
algorithm. We find that, under appropriate conditions (such as low
temperatures), the low-energy (i.e., non-Markovian) modes of the bath are most
important. Hence the scalability of the adiabatic quantum algorithm depends on
the infra-red behavior of the environment: a reasonably small coupling to the
three-dimensional electromagnetic field does not destroy the scaling behavior,
whereas phonons or localized degrees of freedom can be problematic. PACS:
03.67.Pp, 03.67.Lx, 03.67.-a, 03.65.Yz
Lokale Clanchefs im römischen Nordafrika
Im Zentrum der Untersuchung stehen Clanchefs und ihre Rolle bei der
Integration von Nomadenstämmen unter römische Verwaltung in den Jahren der
römischen Herrschat über Nordafrika von 146 v. Chr. bis ins 5. Jh. n. Chr.
Ausgangspunkt der Ăśberlegungen war, daĂź die ausschlieĂźlich in
Personenverbänden verlaufende Organisation nomadischer Stämme für die nach dem
Kriterium der Ortsfestigkeit operierende römische Verwaltung nach der
Eroberung Nordafrikas 146 v. Chr. eine neuartige Herausforderung darstellte.
Und es waren v. a. die Anführer dieser Stämme, deren lokale Autonomieansprüche
durch die gegenüber den vorherigen Numiderkönigen intensivere
Kontrolltätigkeit der Römer eingeschränkt wurden und die deshalb verstärkt
rebellierten. Deshalb wurde untersucht, wie der römischen Verwaltung eine
Adaption an diese andersartigen lokalen Machtstrukturen gelang. In der Tat ist
die zunehmende Stabilität der römischen Herrschat ab dem 2. Jh. n. Chr. nicht
unwesentlich mit der erfolgreichen Einbindung nomadischer Clanchefs verknĂĽpt,
die z. B. durch Bürgerrechtsverleihungen privilegiert wurden, während das
Machtgefüge innerhalb der Stämme und damit lokale Machtstrukturen weitgehend
unangetastet blieben. Dies fĂĽhrte zu der ambivalenten Situation, daĂź der
schwindende Einfluss Roms in Nordafrika ab dem 5. Jh. zwar in ein erneutes
Erstarken der Territorialmacht von Nomadenstämmen mündete, deren Anführer sich
aber weiterhin auf Rom als Quelle ihres Prestiges beriefen.The study focusses on tribal chiefs and their role in integrating nomadic
tribes into the Roman administration between 146 BC and the 5th century AD
when Rome ruled over North Africa. It acted on the assumption that the
specific organizational structure of nomadic tribes, based primarily on
personal loyalties, represented a novel challenge for the Roman
administration, which was based on a sedentary structure of its subjects.
Similarly, the Roman administration posed a threat to the nomadic chietains as
well, because it manifested an intensified form of control in comparison with
the Numidian kings who had previously ruled large parts of North Africa.
Therefore, it was predominantly these chietains who initially led the fierce
resistance against Rome. The study raised the question how the Roma
The Properties of the Heterogeneous Shakhbazyan Groups of Galaxies in the SDSS
We present a systematic study of the sub-sample of Shakhbazyan groups (SHKs)
covered by the Sloan Digital Sky Survey Data Release--5 (SDSS-5). SHKs probe an
environment with characteristics which are intermediate between those of loose
and very compact groups. Surprisingly, we found that several groups identifying
algorithms (e.g. Berlind et al. 2006, Tago et al. 2008) miss this type of
structures. Using the SDSS-5 spectroscopic data and the photometric redshifts
derived in D'Abrusco et al. 2007, we identified possible group members in
photometric redshift space and derived, for each group, several individual
properties. We also combined pointed and stacked Rosat All Sky Survey data to
investigate the X-ray luminosities of these systems. Our study confirms that
the majority of groups are physical entities with richness in the range 3--13
galaxies, and properties ranging between those of loose and compact groups. We
confirm that SHK groups are richer in early-type galaxies than the surrounding
environment and the field, as expected from the morphology-density relation and
from the selection of groups of red galaxies. Furthermore, our work supports
the existence of two sub-classes of structures, the first one being formed by
compact and isolated groups and the second formed by extended structures. We
suggest that while the first class of objects dwells in less dense regions like
the outer parts of clusters or the field, possibly sharing the properties of
Hickson Compact Groups, the more extended structures represent a mixture of
[core+halo] configurations and cores of rich clusters. X-ray luminosities for
SHKs are generally consistent with these results and with the expectations for
the L_X-sigma_v relation, but also suggest the velocity dispersions reported in
literature are underestimated for some of the richest systems.Comment: 20 pages, 14 figures, 4 tables. Accepted for publication by MNRA
Willingness-to-Pay for Genetic Attributes in Aquaculture Industries
The genetic make-up of fish stocks is an important factor in aquaculture production. Choice-based conjoint analysis is used to determine importance of genetic improvements to grow-out producers and an estimated willingness-to-pay for selected attributes. Results from a national survey of aquaculture producers, reveal growth rate as the most important attribute.Resource /Energy Economics and Policy,
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