6,143 research outputs found
Dust-penetrated morphology in the high-redshift universe: clues from NGC 922
Results from the Hubble Deep Field (HDF) North and South show a large
percentage of high-redshift galaxies whose appearance falls outside traditional
classification systems. The nature of these objects is poorly understood, but
sub-mm observations indicate that at least some of these systems are heavily
obscured (Sanders 2000). This raises the intriguing possibility that a
physically meaningful classification system for high-redshift galaxies might be
more easily devised at rest-frame infrared wavelengths, rather than in the
optical regime. Practical realization of this idea will become possible with
the advent of the Next Generation Space Telescope (NGST). In order to explore
the capability of NGST for undertaking such science, we present NASA-IRTF and
SCUBA observations of NGC 922, a chaotic system in our local Universe which
bears a striking resemblance to objects such as HDF 2-86 (z=0.749) in the HDF
North. If objects such as NGC 922 are common at high-redshifts, then this
galaxy may serve as a local morphological `Rosetta stone' bridging low and
high-redshift populations. In this paper we demonstrate that quantitative
measures of galactic structure are recoverable in the rest-frame infrared for
NGC 922 seen at high redshifts using NGST, by simulating the appearance of this
galaxy at redshifts z=0.7 and z=1.2 in rest-frame K'. Our results suggest that
the capability of efficiently exploring the rest-wavelength IR morphology of
high-z galaxies should probably be a key factor in deciding the final choice of
instruments for the NGST.Comment: 7 pages, 12 Figures. Accepted for publication in A&A. Better version
of the figures can be found at http://www.inaoep.mx/~puerari/ngs
Biodiversity in drinking water distribution systems:a brief review
In drinking water distribution systems, three groups of living organisms are usually found in the biofilm and circulating water: heterotrophic bacteria, free-living protozoa, and macro-invertebrates. Indirect evidence suggests that protozoa grazing in distribution systems can partially eliminate biomass production and accidental microbiological pollution. This paper examines the biodiversit in drinking water distribution systems
Gravitational torques in spiral galaxies: gas accretion as a driving mechanism of galactic evolution
The distribution of gravitational torques and bar strengths in the local
Universe is derived from a detailed study of 163 galaxies observed in the
near-infrared. The results are compared with numerical models for spiral galaxy
evolution. It is found that the observed distribution of torques can be
accounted for only with external accretion of gas onto spiral disks. Accretion
is responsible for bar renewal - after the dissolution of primordial bars - as
well as the maintenance of spiral structures. Models of isolated, non-accreting
galaxies are ruled out. Moderate accretion rates do not explain the
observational results: it is shown that galactic disks should double their mass
in less than the Hubble time. The best fit is obtained if spiral galaxies are
open systems, still forming today by continuous gas accretion, doubling their
mass every 10 billion years.Comment: 4 pages, 2 figures, Astronomy and Astrophysics Letters (accepted
Glucocorticoid receptor expression in 20 solid tumor types using immunohistochemistry assay.
BackgroundGlucocorticoid receptor (GR) activity plays a role in many aspects of human physiology and may play a crucial role in chemotherapy resistance in a wide variety of solid tumors. A novel immunohistochemistry (IHC) based assay has been previously developed and validated in order to assess GR immunoreactivity in triple-negative breast cancer. The current study investigates the standardized use of this validated assay to assess GR expression in a broad range of solid tumor malignancies.MethodsArchived formalin-fixed paraffin-embedded tumor bank samples (n=236) from 20 different solid tumor types were analyzed immunohistochemically. Nuclear staining was reported based on the H-score method using differential intensity scores (0, 1+, 2+, or 3+) with the percent stained (out of at least 100 carcinoma cells) recorded at each intensity.ResultsGR was expressed in all tumor types that had been evaluated. Renal cell carcinoma, sarcoma, cervical cancer, and melanoma were those with the highest mean H-scores, indicating high levels of GR expression. Colon, endometrial, and gastric cancers had lower GR staining percentages and intensities, resulting in the lowest mean H-scores.ConclusionA validated IHC assay revealed GR immunoreactivity in all solid tumor types studied and allowed for standardized comparison of reactivity among the different malignancies.ImpactBaseline expression levels of GR may be a useful biomarker when pharmaceutically targeting GR in research or clinical setting
Dust penetrated morphology in the high redshift Universe
Images from the Hubble Deep Field (HDF) North and South show a large
percentage of dusty, high redshift galaxies whose appearance falls outside
traditional classification systems. The nature of these objects is not yet
fully understood. Since the HDF preferentially samples restframe UV light, HDF
morphologies are not dust or `mask' penetrated. The appearance of high redshift
galaxies at near-infrared restframes remains a challenge for the New
Millennium. The Next Generation Space Telescope (NGST) could routinely provide
us with such images. In this contribution, we quantitatively determine the
dust-penetrated structures of high redshift galaxies such as NGC 922 in their
near-infrared restframes. We show that such optically peculiar objects may
readily be classified using the dust penetrated z ~ 0 templates of Block and
Puerari (1999) and Buta and Block (2001).Comment: 4 pages, 2 figures. Presented at the conference "The Link between
Stars and Cosmology", 26-30 March, 2001, Puerto Vallarta, Mexico. To be
published by Kluwer, eds. M. Chavez, A. Bressan, A. Buzzoni, and D. Mayya.
High-resolution version of Figure 2 can be found at
http://www.inaoep.mx/~puerari/conf_puertovallart
Codes of conduct, private information and repeated games
We examine self-referential games in which there is a chance of understanding an opponent's
intentions. Even when this source of information is weak, we are able to prove a folk-like theorem
for repeated self-referential games with private monitoring. Our main focus is on the interaction
of two sources of information about opponents' play: direct observation of the opponent's
intentions, and indirect observation of the opponent's play in a repeated setting.Juan Block acknowledges support from the Cambridge-INET Institute,
and David Levine thanks the National Science Foundation (Grant SES-0851315) and the European University Institute
for financial support.This is the author accepted manuscript. The final version is available from Springer at http://dx.doi.org/10.1007/s00182-015-0498-2
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