1,045 research outputs found
Anisotropy of the space orientation of radio sources. I: The catalog
A catalog of the extended extragalactic radio sources consisting of 10461
objects is compiled based on the list of radio sources of the FIRST survey. A
total of 1801 objects are identified with galaxies and quasars of the SDSS
survey and the Veron-Veron catalog. The distribution of the position angles of
the axes of radio sources from the catalog is determined, and the probability
that this distribution is equiprobable is shown to be less then 10^(-7). This
result implies that at Z equal to or smaller then 0.5, spatial orientation of
the axes of radio sources is anisotropic at a statistically significant level.Comment: 8 pages, 7 figure
Analysis of multistory frames with light gauge steel panel infills
PREFACE This report was originally presented as a thesis to the Faculty of the Graduate School of Cornell University in partial fulfillment of the requirements for the degree of Doctor of Philosophy, conferred in August 1972. The author wishes to thank Professor Arthur H. Nilson, Project Director, and Professor Robert G. Sexsmith, Principal Investigator, for the help and guidance that made this work possible. This investigation was supported by the American Iron and Steel Institute
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Final optic protection designs for ICF containment chambers
The output from a laser-driven high-fain ICF target in the laboratory microfusion facility (LMF) target chamber could produce enough x-rays, shrapnel, and debris to severely damage the laser's final optics. If the final optics were left unprotected, the replacement and reinstallation costs for each beam would exceed 2.7M. To avoid these excessive costs, we must design a reliable optics protection system. This requires that we define the hazardous environment to which the optics are exposed. The geometrical layout for the 68 beams of the 10 megajoule laser shows the final optics placed at 25 meters from the target. The final optic will be a 2--5 cm thick debris shield (200K focussing lens. Each of the 68 beams will deliver 150 kJ of 0.35 ..mu..m (3..omega..) light and will consist of either a 4 /times/ 4 or a 2 /times/ 8 array of beamlets, with each beamlet aperture having dimensions of 29 cm /times/ 29cm. This produces a 3..omega.. energy density at the final optic of 12J/cm/sup 2/ average and 225-30J/cm/sup 2/peak. 8 refs., 4 figs., 1 tab
The HI Content of Compact Groups of Galaxies
The HI content of Hickson Compact Groups in the southern hemisphere is
measured using data from the HI Parkes All Sky Survey (HIPASS), and dedicated
observations using the narrowband filter on the Multibeam instrument on the
Parkes telescope. The expected HI mass of these groups was estimated using the
luminosity, diameter and morphological types of the member galaxies, calibrated
from published data. Taking careful account of non-detection limits, the
results show that the compact group population that has been detected by these
observations has an HI content similar to that of galaxies in the reference
field sample. The upper limits for the undetected groups lie within the normal
range; improvement of these limits will require a large increase in
sensitivity.Comment: 27 pages, 5 figures. Accepted for publication in PAS
Evaluation of a simple hyphenated system for flow injection solid-phase pre-concentration and capillary electrophoresis
In this work, the development and evaluation of a hyphenated flow injection-capillary electrophoresis system with on-line pre-concentration is described. Preliminary tests were performed to investigate the influence of flow rates over the analytical signals. Results revealed losses in terms of sensitivity of the FIA-CE system when compared to the conventional CE system. To overcome signal decrease and to make the system more efficient, a lower flow rate was set and an anionic resin column was added to the flow manifold in order to pre-concentrate the analyte. The pre-concentration FIA-CE system presented a sensitivity improvement of about 660% and there was only a small increase of 8% in total peak dispersion. These results have confirmed the great potential of the proposed system for many analytical tasks especially for low concentration samples.Nesse trabalho apresentamos um sistema hifenizado envolvendo as duas técnicas analíticas: eletroforese capilar (CE) e análises por injeção em fluxo (FIA), denominado de FIA-CE. Parâmetros como a influência do fluxo e a natureza do eluente frente ao sistema CE foram avaliados. O sistema demonstrou-se promissor quanto à possibilidade de aplicações em diferentes áreas da química analítica. O aumento da sensibilidade foi da ordem de 660% devido ao emprego de colunas de troca iônica no sistema FIA. Esse resultado comprova o grande potencial do sistema FIA-CE.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)CNPqFAPES
The Effect of Selection for Desiccation Resistance on Cold Tolerance of Drosophila Melanogaster
Low Temperature and Desiccation Stress Are Thought to Be Mechanistically Similar in Insects, and Several Studies Indicate that There is a Degree of Cross-Tolerance between Them, such that Increased Cold Tolerance Results in Greater Desiccation Tolerance and Vice Versa. This Assertion is Tested at an Evolutionary Scale by Examining Basal Cold Tolerance, Rapid Cold-Hardening (RCH) and Chill Coma Recovery in Replicate Populations of Drosophila Melanogaster Selected for Desiccation Resistance (With Controls for Both Selection and Concomitant Starvation) for over 50 Generations. All of the Populations Display a RCH Response, and There is No Effect of Selection Regime on RCH or Basal Cold Tolerance, Although There Are Differences in Basal Cold Tolerance between Sampling Dates, Apparently Related to Inter-Individual Variation in Development Time. Flies Selected for Desiccation Tolerance Recover from Chill Coma Slightly, But Significantly, Faster Than Control and Starvation-Control Flies. These Findings Provide Little Support for Cross-Tolerance between Survival of Near-Lethal Cold and Desiccation Stress in D. Melanogaster. © 2007 the Authors
Double Bars, Inner Disks, and Nuclear Rings in Early-Type Disk Galaxies
We present results from an imaging survey of an unbiased sample of
thirty-eight early-type (S0--Sa), low-inclination, optically barred galaxies in
the field. Our goal was to find and characterize central stellar and gaseous
structures: secondary bars, inner disks, and nuclear rings. Bars inside bars
are surprisingly common: at least one quarter of the sample galaxies (possibly
as many as 40%) are double-barred, with no preference for Hubble type or the
strength of the primary bar. A typical secondary bar is ~12% of the size of its
primary bar and 240--750 pc in radius. We see no significant effect of
secondary bars on nuclear activity. We also find kiloparsec-scale inner disks
in at least 20% of our sample, almost exclusively in S0 galaxies. These disks
are on average 20% the size of their host bar, and show a wider range of
relative sizes than do secondary bars. Nuclear rings are present in about a
third of our sample. Most are dusty, sites of current or recent star formation,
or both; such rings are preferentially found in Sa galaxies. Three S0 galaxies
(15% of the S0's) appear to have purely stellar nuclear rings, with no evidence
for dust or recent star formation. The fact that these central stellar
structures are so common indicates that the inner regions of early-type barred
galaxies typically contain dynamically cool and disklike structures. This is
especially true for S0 galaxies, where secondary bars, inner disks, and/or
stellar nuclear rings are present at least two thirds of the time. (abridged)Comment: LaTeX, 15 pages, 7 EPS figures; to appear in The Astronomical Journal
(July 2002
Spitzer Observations of Passive and Star Forming Early-type Galaxies: an Infrared Color-Color Sequence
We describe the infrared properties of a large sample of early type galaxies,
comparing data from the Spitzer archive with Ks-band emission from 2MASS. While
most representations of this data result in correlations with large scatter, we
find a remarkably tight relation among colors formed by ratios of luminosities
in Spitzer-MIPS (24, 70 and 160 um) bands and the Ks-band. Remarkably, this
correlation among E and S0 galaxies follows that of nearby normal galaxies of
all morphological types. In particular, the tight infrared color-color
correlation for S0 galaxies alone follows that of the entire Hubble sequence of
normal galaxies, roughly in order of galaxy type from ellipticals to spirals to
irregulars. The specific star formation rate of S0 galaxies estimated from the
24um luminosity increases with decreasing Ks-band luminosity (or stellar mass)
from essentially zero, as with most massive ellipticals, to rates typical of
irregular galaxies. Moreover, the luminosities of the many infrared-luminous S0
galaxies can significantly exceed those of the most luminous (presumably
post-merger) E galaxies. Star formation rates in the most infrared-luminous S0
galaxies approach 1-10 solar masses per year. Consistently with this picture we
find that while most early-type galaxies populate an infrared red sequence,
about 24% of the objects (mostly S0s) are in an infrared blue cloud together
with late type galaxies. For those early-type galaxies also observed at radio
frequencies we find that the far-infrared luminosities correlate with the mass
of neutral and molecular hydrogen, but the scatter is large. This scatter
suggests that the star formation may be intermittent or that similar S0
galaxies with cold gaseous disks of nearly equal mass can have varying radial
column density distributions that alter the local and global SF rates.Comment: 14 Pages, 13 figures, Accepted by Ap
A dinucleotide deletion in the ankyrin promoter alters gene expression, transcription initiation and TFIID complex formation in hereditary spherocytosis
Ankyrin defects are the most common cause of hereditary spherocytosis (HS). In some HS patients, mutations in the ankyrin promoter have been hypothesized to lead to decreased ankyrin mRNA synthesis. The ankyrin erythroid promoter is a member of the most common class of mammalian promoters which lack conserved TATA, initiator or other promoter cis elements and have high G+C content, functional Sp1 binding sites and multiple transcription initiation sites. We identified a novel ankyrin gene promoter mutation, a TG deletion adjacent to a transcription initiation site, in a patient with ankyrin-linked HS and analyzed its effects on ankyrin expression. In vitro, the mutant promoter directed decreased levels of gene expression, altered transcription initiation site utilization and exhibited defective binding of TATA-binding protein (TBP) and TFIID complex formation. In a transgenic mouse model, the mutant ankyrin promoter led to abnormalities in gene expression, including decreased expression of a reporter gene and altered transcription initiation site utilization. These data indicate that the mutation alters ankyrin gene transcription and contributes to the HS phenotype by decreasing ankyrin gene synthesis via disruption of TFIID complex interactions with the ankyrin core promoter. These studies support the model that in promoters that lack conserved cis elements, the TFIID complex directs preinitiation complex formation at specific sites in core promoter DNA and provide the first evidence that disruption of TBP binding and TFIID complex formation in this type of promoter leads to alterations in start site utilization, decreased gene expression and a disease phenotype in viv
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