Models of the ICM with Heating and Cooling: Explaining the Global and Structural X-ray Properties of Clusters

(Abridged) Theoretical models that include only gravitationally-driven processes fail to match the observed mean X-ray properties of clusters. As a result, there has recently been increased interest in models in which either radiative cooling or entropy injection play a central role in mediating the properties of the intracluster medium. Both sets of models give reasonable fits to the mean properties of clusters, but cooling only models result in fractions of cold baryons in excess of observationally established limits and the simplest entropy injection models do not treat the "cooling core" structure present in many clusters and cannot account for entropy profiles revealed by recent X-ray observations. We consider models that marry radiative cooling with entropy injection, and confront model predictions for the global and structural properties of massive clusters with the latest X-ray data. The models successfully and simultaneously reproduce the observed L-T and L-M relations, yield detailed entropy, surface brightness, and temperature profiles in excellent agreement with observations, and predict a cooled gas fraction that is consistent with observational constraints. The model also provides a possible explanation for the significant intrinsic scatter present in the L-T and L-M relations and provides a natural way of distinguishing between clusters classically identified as "cooling flow" clusters and dynamically relaxed "non-cooling flow" clusters. The former correspond to systems that had only mild levels (< 300 keV cm^2) of entropy injection, while the latter are identified as systems that had much higher entropy injection. This is borne out by the entropy profiles derived from Chandra and XMM-Newton.Comment: 20 pages, 15 figures, accepted for publication in the Astrophysical Journa

An Eccentric Hot Jupiter Orbiting the Subgiant HD 185269

We report the detection of a Jupiter-mass planet in a 6.838 day orbit around the 1.28 solar mass subgiant HD 185269. The eccentricity of HD 185269b (e = 0.30) is unusually large compared to other planets within 0.1 AU of their stars. Photometric observations demonstrate that the star is constant to +/-0.0001 mag on the radial velocity period, strengthening our interpretation of a planetary companion. This planet was detected as part of our radial velocity survey of evolved stars located on the subgiant branch of the H-R diagram--also known as the Hertzsprung Gap. These stars, which have masses between 1.2 and 2.5 solar masses, play an important role in the investigation of the frequency of extrasolar planets as a function of stellar mass.Comment: 18 pages, 4 figures, 3 tables, ApJ in press (scheduled for Dec 2006, v652n2

Luminous superclusters: remnants from inflation

We derive the luminosity and multiplicity functions of superclusters compiled for the 2dF Galaxy Redshift Survey, the Sloan Digital Sky Survey (Data Release 4), and for three samples of simulated superclusters. We find for all supercluster samples Density Field (DF) clusters, which represent high-density peaks of the class of Abell clusters, and use median luminosities/masses of richness class 1 DF-clusters to calculate relative luminosity/mass functions. We show that the fraction of very luminous (massive) superclusters in real samples is more than tenfolds greater than in simulated samples. Superclusters are generated by large-scale density perturbations which evolve very slowly. The absence of very luminous superclusters in simulations can be explained either by non-proper treatment of large-scale perturbations, or by some yet unknown processes in the very early Universe.Comment: 6 pages, 3 Figures, submitted for Astronomy and Astrophysic

The N2K Consortium. II. A Transiting Hot Saturn Around HD 149026 With a Large Dense Core

Doppler measurements from Subaru and Keck have revealed radial velocity variations in the V=8.15, G0IV star HD 149026 consistent with a Saturn-Mass planet in a 2.8766 day orbit. Photometric observations at Fairborn Observatory have detected three complete transit events with depths of 0.003 mag at the predicted times of conjunction. HD 149026 is now the second brightest star with a transiting extrasolar planet. The mass of the star, based on interpolation of stellar evolutionary models, is 1.3 +/- 0.1 solar masses; together with the Doppler amplitude, K=43.3 m s^-1, we derive a planet mass Msin(i)=0.36 Mjup, and orbital radius of 0.042 AU. HD 149026 is chromospherically inactive and metal-rich with spectroscopically derived [Fe/H]=+0.36, Teff=6147 K, log g=4.26 and vsin(i)=6.0 km s^-1. Based on Teff and the stellar luminosity of 2.72 Lsun, we derive a stellar radius of 1.45 Rsun. Modeling of the three photometric transits provides an orbital inclination of 85.3 +/- 1.0 degrees and (including the uncertainty in the stellar radius) a planet radius of 0.725 +/- 0.05 Rjup. Models for this planet mass and radius suggest the presence of a ~67 Mearth core composed of elements heavier than hydrogen and helium. This substantial planet core would be difficult to construct by gravitational instability.Comment: 25 pages, 5 figures, accepted by the Astrophysical Journa

Desperately seeking niches: Grassroots innovations and niche development in the community currency field

The sustainability transitions literature seeks to explain the conditions under which technological innovations can diffuse and disrupt existing socio-technical systems through the successful scaling up of experimental ‘niches’; but recent research on ‘grassroots innovations’ argues that civil society is a promising but under-researched site of innovation for sustainability, albeit one with very different characteristics to the market-based innovation normally considered in the literature. This paper aims to address that research gap by exploring the relevance of niche development theories in a civil society context. To do this, we examine a growing grassroots innovation – the international field of community currencies – which comprises a range of new socio-technical configurations of systems of exchange which have emerged from civil society over the last 30 years, intended to provide more environmentally and socially sustainable forms of money and finance. We draw on new empirical research from an international study of these initiatives comprising primary and secondary data and documentary sources, elite interviews and participant observation in the field. We describe the global diffusion of community currencies, and then conduct a niche analysis to evaluate the utility of niche theories for explaining the development of the community currency movement. We find that some niche-building processes identified in the existing literature are relevant in a grassroots context: the importance of building networks, managing expectations and the significance of external ‘landscape’ pressures, particularly at the level of national-type. However, our findings suggest that existing theories do not fully capture the complexity of this type of innovation: we find a diverse field addressing a range of societal systems (money, welfare, education, health, consumerism), and showing increasing fragmentation (as opposed to consolidation and standardisation); furthermore, there is little evidence of formalised learning taking place but this has not hampered movement growth. We conclude that grassroots innovations develop and diffuse in quite different ways to conventional innovations, and that niche theories require adaptation to the civil society context

A Bayesian method for evaluating and discovering disease loci associations

Background: A genome-wide association study (GWAS) typically involves examining representative SNPs in individuals from some population. A GWAS data set can concern a million SNPs and may soon concern billions. Researchers investigate the association of each SNP individually with a disease, and it is becoming increasingly commonplace to also analyze multi-SNP associations. Techniques for handling so many hypotheses include the Bonferroni correction and recently developed Bayesian methods. These methods can encounter problems. Most importantly, they are not applicable to a complex multi-locus hypothesis which has several competing hypotheses rather than only a null hypothesis. A method that computes the posterior probability of complex hypotheses is a pressing need. Methodology/Findings: We introduce the Bayesian network posterior probability (BNPP) method which addresses the difficulties. The method represents the relationship between a disease and SNPs using a directed acyclic graph (DAG) model, and computes the likelihood of such models using a Bayesian network scoring criterion. The posterior probability of a hypothesis is computed based on the likelihoods of all competing hypotheses. The BNPP can not only be used to evaluate a hypothesis that has previously been discovered or suspected, but also to discover new disease loci associations. The results of experiments using simulated and real data sets are presented. Our results concerning simulated data sets indicate that the BNPP exhibits both better evaluation and discovery performance than does a p-value based method. For the real data sets, previous findings in the literature are confirmed and additional findings are found. Conclusions/Significance: We conclude that the BNPP resolves a pressing problem by providing a way to compute the posterior probability of complex multi-locus hypotheses. A researcher can use the BNPP to determine the expected utility of investigating a hypothesis further. Furthermore, we conclude that the BNPP is a promising method for discovering disease loci associations. © 2011 Jiang et al

Agro-materials : a bibliographic review

Facing the problems of plastic recycling and fossil resources exhaustion, the use of biomass to conceive new materials appears like a reasonable solution. Two axes of research are nowadays developed : on the one hand the synthesis of biodegradable plastics, whichever the methods may be, on the other hand the utilization of raw biopolymers, which is the object of this paper. From this perspective, the “plastic” properties of natural polymers, the caracteristics of the different classes of polymers, the use of charge in vegetable matrix and the possible means of improving the durability of these agro-materials are reviewed

RATAN-600 7.6-cm Deep Sky Strip Surveys at the Declination of the SS433 Source During the 1980-1999 Period. Data Reduction and the Catalog of Radio Sources in the Right-Ascension Interval 7h < R.A. < 17h

We use two independent methods to reduce the data of the surveys made with RATAN-600 radio telescope at 7.6 cm in 1988-1999 at the declination of the SS433 source. We also reprocess the data of the "Cold" survey (1980-1981). The resulting RCR (RATAN COLD REFINED) catalog contains the right ascensions and fluxes of objects identified with those of the NVSS catalog in the right-ascension interval 7h < R.A. < 17h. We obtain the spectra of the radio sources and determine their spectral indices at 3.94 and 0.5 GHz. The spectra are based on the data from all known catalogs available from the CATS, Vizier, and NED databases, and the flux estimates inferred from the maps of the VLSS and GB6 surveys. For 245 of the 550 objects of the RCR catalog the fluxes are known at two frequencies only: 3.94 GHz (RCR) and 1.4 GHz (NVSS). These are mostly sources with fluxes smaller than 30 mJy. About 65% of these sources have flat or inverse spectra (alpha > -0.5). We analyze the reliability of the results obtained for the entire list of objects and construct the histograms of the spectral indices and fluxes of the sources. Our main conclusion is that all 10-15 mJy objects found in the considered right-ascension interval were already included in the decimeter-wave catalogs.Comment: 26 pages, 18 figure