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

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

A folk theorem with codes of conduct and communication

We study self-referential games in which players have the ability to commit to a code of conduct—a complete description of how they play and their opponents should play. Each player receives a private signal about each others’ code of conduct and their codes of conduct specify how to react to these signals. When only some players receive informative signals, players are allowed to communicate using public messages. Our characterization of the effect of communication on the equilibrium payoffs yields a folk theorem and players share their private information truthfully in equilibrium. We also provide an application of codes of conduct: games that are played through computer programs.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 final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s40505-016-0107-

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

A folk theorem with codes of conduct and communication

This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s40505-016-0107-yWe study self-referential games in which players have the ability to commit to a code of conduct—a complete description of how they play and their opponents should play. Each player receives a private signal about each others’ code of conduct and their codes of conduct specify how to react to these signals. When only some players receive informative signals, players are allowed to communicate using public messages. Our characterization of the effect of communication on the equilibrium payoffs yields a folk theorem and players share their private information truthfully in equilibrium. We also provide an application of codes of conduct: games that are played through computer programs.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

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

Very Luminous Carbon Stars in the Outer Disk of the Triangulum Spiral Galaxy

Stars with masses in the range from about 1.3 to 3.5 Mo pass through an evolutionary stage where they become carbon stars. In this stage, which lasts a few Myr, these stars are extremely luminous pulsating giants. They are so luminous in the near-infrared that just a few of them can double the integrated luminosity of intermediate-age (0.6 to 2 Gyr) Magellanic Cloud clusters at 2.2 microns. Astronomers routinely use such near-infrared observations to minimize the effects of dust extinction, but it is precisely in this band that carbon stars can contribute hugely. The actual contribution of carbon stars to the outer disk light of evolving spiral galaxies has not previously been morphologically investigated. Here we report new and very deep near-IR images of the Triangulum spiral galaxy M33=NGC 598, delineating spectacular arcs of carbon stars in its outer regions. It is these arcs which dominate the near-infrared m=2 Fourier spectra of M33. We present near-infrared photometry with the Hale 5-m reflector, and propose that the arcs are the signature of accretion of low metallicity gas in the outer disk of M33.Comment: 4 pages, 4 figures. Revised version submitted to A&A Letter

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