How typical is the Coma cluster?

Coma is frequently used as the archetype z~0 galaxy cluster to compare higher redshift work against. It is not clear, however, how representative the Coma cluster is for galaxy clusters of its mass or X-ray luminosity, and significantly: recent works have suggested that the galaxy population of Coma may be in some ways anomolous. In this work, we present a comparison of Coma to an X-ray selected control sample of clusters. We show that although Coma is typical against the control sample in terms of its internal kinematics (substructure and velocity dispersion profile), it has a significantly high (~3sigma) X-ray temperature set against clusters of comparable mass. By de-redshifting our control sample cluster galaxies star-formation rates using a fit to the galaxy main sequence evolution at z < 0.1, we determine that the typical star-formation rate of Coma galaxies as a function of mass is higher than for galaxies in our control sample at a confidence level of > 99 per cent. One way to alleviate this discrepency and bring Coma in-line with the control sample would be to have the distance to Coma to be slightly lower, perhaps through a non-negligible peculiar velocity with respect to the Hubble expansion, but we do not regard this as likely given precision measurements using a variety of approaches. Therefore in summary, we urge caution in using Coma as a z~0 baseline cluster in galaxy evolution studies.Comment: accepted for publication in MNRA

Asteroseismic modeling of 16 Cyg A & B using the complete Kepler data set

Asteroseismology of bright stars with well-determined properties from parallax measurements and interferometry can yield precise stellar ages and meaningful constraints on the composition. We substantiate this claim with an updated asteroseismic analysis of the solar-analog binary system 16 Cyg A & B using the complete 30-month data sets from the Kepler space telescope. An analysis with the Asteroseismic Modeling Portal (AMP), using all of the available constraints to model each star independently, yields the same age ($t=7.0 \pm 0.3$ Gyr) and composition ($Z=0.021 \pm 0.002$, $Y_i=0.25 \pm 0.01$) for both stars, as expected for a binary system. We quantify the accuracy of the derived stellar properties by conducting a similar analysis of a Kepler-like data set for the Sun, and we investigate how the reliability of asteroseismic inference changes when fewer observational constraints are available or when different fitting methods are employed. We find that our estimates of the initial helium mass fraction are probably biased low by 0.02-0.03 from neglecting diffusion and settling of heavy elements, and we identify changes to our fitting method as the likely source of small shifts from our initial results in 2012. We conclude that in the best cases reliable stellar properties can be determined from asteroseismic analysis even without independent constraints on the radius and luminosity.Comment: 5 emulateapj pages, 1 table, 1 figure. ApJ Letters, accepte

Origin of the 0.25-anomaly in the nonlinear conductance of a quantum point contact

We calculate the non-linear conductance of a quantum point contact using the non-equilibrium Greens function technique within the Hartree approximation of spinless electrons. We quantitative reproduce the 0.25-anomaly in the differential conductance (i.e. the lowest plateau at 0.25-0.3*2e^2/h) as well as an upward bending of higher conductance half-integer plateaus seen in the experiments, and relate these features to the non-linear screening and pinning effects.Comment: 6 pages, 4 figure

Electronic and optical properties of quantum wells embedded in wrinkled nanomembranes

The authors theoretically investigate quantum confinement and transition energies in quantum wells (QWs) asymmetrically positioned in wrinkled nanomembranes. Calculations reveal that the wrinkle profile induces both blue- and redshifts depending on the lateral position of the QW probed. Relevant radiative transistions include the ground state of the electron (hole) and excited states of the hole (electron). Energy shifts as well as stretchability of the structure are studied as a function of wrinkle amplitude and period. Large tunable bandwidths of up to 70 nm are predicted for highly asymmetric wrinkled QWs.Comment: 3 pages, 4 figures. The following article has been submitted to Applied Physics Letters. After it is published, it will be found at http://apl.aip.or

Intranasal melanoma treated with radiation therapy in three dogs

Three dogs were investigated for chronic unilateral nasal discharge. In all cases CT imaging showed an intranasal mass causing turbinate lysis and no evidence of metastasis. Cytology in cases 1 (a 14-year-old neutered male crossbreed dog) and 2 (a five-year-old neutered male German Shepherd dog) demonstrated a pleomorphic cell population with variable intracellular pigment suspicious of melanocytic neoplasia. Histopathology with immunohistochemistry (Melan-A and vimentin, plus PNL-2 in one case) confirmed the diagnosis of melanoma in all dogs. All dogs were treated with megavoltage radiotherapy using linear accelerators. Cases 1 and 3 (a nine-year-old neutered female beagle dog) received a hypofractionated (4 × 8 Gy) protocol and case 2 received a definitive (12 × 4 Gy) protocol. Complete remission was demonstrated on repeat CT scan five months after diagnosis in case 1 and seven months in case 2. Stable disease was documented on CT at four months for case 3; however, clinical signs in this dog remained controlled for 10 months in total. Case 1 died of unrelated causes five months after diagnosis, case 2 was euthanased due to the development of seizures 13 months after diagnosis, and case 3 was lost to follow-up 12 months after diagnosis. Melanoma should be considered as a rare differential diagnosis for primary nasal neoplasia in the dog and radiation therapy can be used as effective local therapy

FliPer: Checking the reliability of global seismic parameters from automatic pipelines

Our understanding of stars through asteroseismic data analysis is limited by our ability to take advantage of the huge amount of observed stars provided by space missions such as CoRoT, Kepler, K2, and soon TESS and PLATO. Global seismic pipelines provide global stellar parameters such as mass and radius using the mean seismic parameters, as well as the effective temperature. These pipelines are commonly used automatically on thousands of stars observed by K2 for 3 months (and soon TESS for at least around 1 month). However, pipelines are not immune from misidentifying noise peaks and stellar oscillations. Therefore, new validation techniques are required to assess the quality of these results. We present a new metric called FliPer (Flicker in Power), which takes into account the average variability at all measured time scales. The proper calibration of FliPer enables us to obtain good estimations of global stellar parameters such as surface gravity that are robust against the influence of noise peaks and hence are an excellent way to find faults in asteroseismic pipelines.Comment: 4 pages, 3 figures, Proceedings for SF2A 2017 (Paris

"Law is an Odd Thing" - Liberalism and Law in the TV-series "The Good Wife"

The public also receives information on law and the legal professions from fictional entertainment, which has become part of every-day discourse on crime. The American high-gloss television series The Good Wife since 2009 not only dramatizes work and private lives of lawyers but also responds to recent events and debates. With its overall message, The Good Wife joins the liberal camp in the legalpolitical debate

The granular silo as a continuum plastic flow: the hour-glass vs the clepsydra

The granular silo is one of the many interesting illustrations of the thixotropic property of granular matter: a rapid flow develops at the outlet, propagating upwards through a dense shear flow while material at the bottom corners of the container remains static. For large enough outlets, the discharge flow is continuous; however, by contrast with the clepsydra for which the flow velocity depends on the height of fluid left in the container, the discharge rate of granular silos is constant. Implementing a plastic rheology in a 2D Navier-Stokes solver (following the mu(I)-rheology or a constant friction), we simulate the continuum counterpart of the granular silo. Doing so, we obtain a constant flow rate during the discharge and recover the Beverloo scaling independently of the initial filling height of the silo. We show that lowering the value of the coefficient of friction leads to a transition toward a different behavior, similar to that of a viscous fluid, and where the filling height becomes active in the discharge process. The pressure field shows that large enough values of the coefficient of friction ($\simeq$ 0.3) allow for a low-pressure cavity to form above the outlet, and can thus explain the Beverloo scaling. In conclusion, the difference between the discharge of a hourglass and a clepsydra seems to reside in the existence or not of a plastic yield stress.Comment: 6 pages, 6 figure

Sharp two-sided heat kernel estimates for critical Schr\"odinger operators on bounded domains

On a smooth bounded domain \Omega \subset R^N we consider the Schr\"odinger operators -\Delta -V, with V being either the critical borderline potential V(x)=(N-2)^2/4 |x|^{-2} or V(x)=(1/4) dist (x,\partial\Omega)^{-2}, under Dirichlet boundary conditions. In this work we obtain sharp two-sided estimates on the corresponding heat kernels. To this end we transform the Scr\"odinger operators into suitable degenerate operators, for which we prove a new parabolic Harnack inequality up to the boundary. To derive the Harnack inequality we have established a serier of new inequalities such as improved Hardy, logarithmic Hardy Sobolev, Hardy-Moser and weighted Poincar\'e. As a byproduct of our technique we are able to answer positively to a conjecture of E.B.Davies.Comment: 40 page

Resolved stellar population of distant galaxies in the ELT era

The expected imaging capabilities of future Extremely Large Telescopes (ELTs) will offer the unique possibility to investigate the stellar population of distant galaxies from the photometry of the stars in very crowded fields. Using simulated images and photometric analysis we explore here two representative science cases aimed at recovering the characteristics of the stellar populations in the inner regions of distant galaxies. Specifically: case A) at the center of the disk of a giant spiral in the Centaurus Group, (mu B~21, distance of 4.6 Mpc); and, case B) at half of the effective radius of a giant elliptical in the Virgo Cluster (mu~19.5, distance of 18 Mpc). We generate synthetic frames by distributing model stellar populations and adopting a representative instrumental set up, i.e. a 42 m Telescope operating close to the diffraction limit. The effect of crowding is discussed in detail showing how stars are measured preferentially brighter than they are as the confusion limit is approached. We find that (i) accurate photometry (sigma~0.1, completeness >90%) can be obtained for case B) down to I~28.5, J~27.5 allowing us to recover the stellar metallicity distribution in the inner regions of ellipticals in Virgo to within ~0.1 dex; (ii) the same photometric accuracy holds for the science case A) down to J~28.0, K~27.0, enabling to reconstruct of the star formation history up to the Hubble time via simple star counts in diagnostic boxes. For this latter case we discuss the possibility of deriving more detailed information on the star formation history from the analysis of their Horizontal Branch stars. We show that the combined features of high sensitivity and angular resolution of ELTs may open a new era for our knowledge of the stellar content of galaxies of different morphological type up to the distance of the Virgo cluster.Comment: 21 pages, 17 figures, PASP accepted in pubblicatio