Event-Enhanced Quantum Theory And Piecewise Deterministic Dynamics

The standard formalism of quantum theory is enhanced and definite meaning is given to the concepts of experiment, measurement and event. Within this approach one obtains a uniquely defined piecewise deterministic algorithm generating quantum jumps, classical events and histories of single quantum objects. The wave-function Monte Carlo method of Quantum Optics is generalized and promoted to the level of a fundamental process generating all the real events in Nature. The already worked out applications include SQUID-tank model and generalized cloud chamber model with GRW spontaneous localization as a particular case. Differences between the present approach and quantum measurement theories based on environment induced master equations are stressed. Questions: what is classical, what is time, and what are observers are addressed. Possible applications of the new approach are suggested, among them connection between the stochastic commutative geometry and Connes'noncommutative formulation of the Standard Model, as well as potential applications to the theory and practice of quantum computers.Comment: 10 pages, twocolumn, REVTE

Common mental disorders and ethnicity in England : the EMPIRIC Study

Background. There is little population-based evidence on ethnic variation in the most common mental disorders (CMD), anxiety and depression. We compared the prevalence of CMD among representative samples of White, Irish, Black Caribbean, Bangladeshi, Indian and Pakistani individuals living in England using a standardized clinical interview. Method. Cross-sectional survey of 4281 adults aged 16–74 years living in private households in England. CMD were assessed using the Revised Clinical Interview Schedule (CIS-R), a standardized clinical interview. Results. Ethnic differences in the prevalence of CMD were modest, and some variation with age and sex was noted. Compared to White counterparts, the prevalence of CMD was higher to a statistically significant degree among Irish [adjusted rate ratios (RR) 2.09, 95% CI 1.16–2.95, p=0.02] and Pakistani (adjusted RR 2.38, 95% CI 1.25–3.53, p=0.02) men aged 35–54 years, even after adjusting for differences in socio-economic status. Higher rates of CMD were also observed among Indian and Pakistani women aged 55–74 years, compared to White women of similar age. The prevalence of CMD among Bangladeshi women was lower than among White women, although this was restricted to those not interviewed in English. There were no differences in rates between Black Caribbean and White samples. Conclusions. Middle-aged Irish and Pakistani men, and older Indian and Pakistani women, had significantly higher rates of CMD than their White counterparts. The very low prevalence of CMD among Bangladeshi women contrasted with high levels of socio-economic deprivation among this group. Further study is needed to explore reasons for this variation

Do Credit Market Barriers Exist for Minority and Women Entrepreneurs?

This paper examines whether methodological deficiencies in the literature on discrimination in small business credit markets have a significant impact on the estimation of discrimination and provides a preliminary investigation into the causes of discrimination in these markets. We find substantial, statistically significant evidence of discrimination in loan approval against black-owned and Hispanic-owned businesses in 1998 with additional control variables, with a variety of different specifications, and with a simultaneous model of the application and loan-denial decisions. We also find that discrimination in small business lending may take the form of statistical discrimination, driven by lenders\u27 stereotypes about the ability of black- and Hispanic-owned businesses to succeed under some circumstances. In addition, we find that neither adding additional control variables nor accounting for possible endogeneity alters the conclusion that there is no discrimination in interest rates on approved loans. We also find, however, that black-owned businesses do face discrimination in interest rates when they deal with some types of lenders, particularly finance companies. Because finance companies specialize in higher-risk borrowers, this finding might indicate that they are willing to consider group-membership as a risk predictor despite the illegality of this practice. These findings suggest that federal financial regulatory agencies should re-double their efforts to uncover and prosecute lenders who discriminate against black- and Hispanic-owned businesses

The phase-diagram of the IGM and the entropy floor of groups and clusters: are clusters born warm?

We point out that two problems of observational cosmology, the facts i) that > 60% of the baryonic content of the universe is not observed at z=0 and ii) that the properties of small clusters do not agree with simple expectations, could be closely related. As shown by recent studies, the shock-heating associated with the formation of large-scale structures heats the intergalactic medium (IGM) and leads to a ``warm IGM'' component for the gas. In the same spirit, we suggest the intracluster medium (ICM) to be a mixture of galaxy-recycled, metal enriched gas and intergalactic gas, shock-heated by the collapsing much larger scales. This could be obtained through two processes: 1) the late infalling gas from the external warm IGM is efficiently mixed within the halo and brings some additional entropy, or 2) the shocks generated by larger non-linear scales are also present within clusters and can heat the ICM. We show that if assumption (1) holds, the entropy brought by the warm IGM is sufficient to explain the observed properties of clusters, in particular the entropy floor and the LX-T relation. On the other hand, we briefly note that the scenario (2) would require a stronger shock-heating because of the larger density of the ICM as compared with filaments. Our scenario of clusters being "born warm" can be checked through the predicted redshift evolution of the entropy floor.Comment: 8 pages, final version published in MNRA

On the Angular Correlation Function of SZ Clusters : Extracting cosmological information from a 2D catalog

We discuss the angular correlation function of Sunyaev-Zel'dovich (SZ)-detected galaxy clusters as a cosmological probe. As a projection of the real-space cluster correlation function, the angular function samples the underlying SZ catalog redshift distribution. It offers a way to study cosmology and cluster evolution directly with the two-dimensional catalog, even before extensive follow-up observations, thereby facilitating the immediate scientific return from SZ surveys. As a simple illustration of the information content of the angular function, we examine its dependence on the parameter pair Om_m, sigma_8 in flat cosmologies. We discuss sources of modeling uncertainty and consider application to the future Planck SZ catalog, showing how these two parameters and the normalization of the SZ flux-mass relation can be simultaneously found when the local X-ray cluster abundance constraint is included.Comment: 11 pages, 5 figures. A&A, 410, 767; corrected typo, published versio

Some theoretical results concerning O 3 ‐NO x ‐VOC chemistry and NO x ‐VOC indicators

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94731/1/jgrd9243.pd

XMM−NewtonXMM-Newton Ω\Omega project: III. Gas mass fraction shape in high redshift clusters

We study the gas mass fraction, $f\_{\rm gas},$ behavior in $XMM-Newton$ $\Omega$ project. The typical $f\_{\rm gas}$ shape of high redshift galaxy clusters follows the global shape inferred at low redshift quite well. This result is consistent with the gravitational instability picture leading to self similar structures for both the dark and baryonic matter. However, the mean $f\_{\rm gas} in distant clusters shows some differences to local ones, indicating a departure from strict scaling. This result is consistent with the observed evolution in the luminosity-temperature relation. We quantitatively investigate this departure from scaling laws. Within the local sample we used, a moderate but clear variation of the amplitude of the gas mass fraction with temperature is found, a trend that weakens in the outer regions. These variations do not explain departure from scaling laws of our distant clusters. An important implication of our results is that the gas fraction evolution, a test of the cosmological parameters, can lead to biased values when applied at radii smaller than the virial radius. From our$XMM$ clusters, the apparent gas fraction at the virial radius is consistent with a non-evolving universal value in a high matter density model and not with a concordance.Comment: Accepted, A&A, in pres

The XMM Cluster Survey: Forecasting cosmological and cluster scaling-relation parameter constraints

We forecast the constraints on the values of sigma_8, Omega_m, and cluster scaling relation parameters which we expect to obtain from the XMM Cluster Survey (XCS). We assume a flat Lambda-CDM Universe and perform a Monte Carlo Markov Chain analysis of the evolution of the number density of galaxy clusters that takes into account a detailed simulated selection function. Comparing our current observed number of clusters shows good agreement with predictions. We determine the expected degradation of the constraints as a result of self-calibrating the luminosity-temperature relation (with scatter), including temperature measurement errors, and relying on photometric methods for the estimation of galaxy cluster redshifts. We examine the effects of systematic errors in scaling relation and measurement error assumptions. Using only (T,z) self-calibration, we expect to measure Omega_m to +-0.03 (and Omega_Lambda to the same accuracy assuming flatness), and sigma_8 to +-0.05, also constraining the normalization and slope of the luminosity-temperature relation to +-6 and +-13 per cent (at 1sigma) respectively in the process. Self-calibration fails to jointly constrain the scatter and redshift evolution of the luminosity-temperature relation significantly. Additional archival and/or follow-up data will improve on this. We do not expect measurement errors or imperfect knowledge of their distribution to degrade constraints significantly. Scaling-relation systematics can easily lead to cosmological constraints 2sigma or more away from the fiducial model. Our treatment is the first exact treatment to this level of detail, and introduces a new `smoothed ML' estimate of expected constraints.Comment: 28 pages, 17 figures. Revised version, as accepted for publication in MNRAS. High-resolution figures available at http://xcs-home.org (under "Publications"

The Effect of Cooling and Preheating on the X-ray Properties of Clusters of Galaxies

We calculate X-ray properties of present-day galaxy clusters from hydrodynamical cosmological simulations of the LCDM cosmology and compare these with recent X-ray observations. Results from three simulations are presented, each of which uses the same initial conditions: a standard adiabatic, Non-radiative model, a Radiative model that includes radiative cooling of the gas, and a Preheating model that also includes cooling but in addition impulsively heats the gas prior to cluster formation. At the end of the simulations, the global cooled baryon fractions in the latter two runs are 15 per cent and 0.4 per cent respectively which bracket the recent result from the K-band luminosity function. We construct cluster catalogues which consist of over 500 clusters and are complete in mass down to 1.18*10^{13} Msun/h. While clusters in the Non-radiative model behave in accord with the self-similar picture, those of the other two models reproduce key aspects of the observed X-ray properties: the core entropy, temperature-mass and luminosity-temperature relations are all in good agreement with recent observations. This agreement stems primarily from an increase in entropy with respect to the Non-radiative clusters. Although the physics affecting the intra-cluster medium is very different in the two models, the resulting cluster entropy profiles are very similar.Comment: Accepted for publication in MNRAS. Minor changes following referee's comment