Multicomponent fluids of hard hyperspheres in odd dimensions

Mixtures of hard hyperspheres in odd space dimensionalities are studied with an analytical approximation method. This technique is based on the so-called Rational Function Approximation and provides a procedure for evaluating equations of state, structure factors, radial distribution functions, and direct correlations functions of additive mixtures of hard hyperspheres with any number of components and in arbitrary odd-dimension space. The method gives the exact solution of the Ornstein--Zernike equation coupled with the Percus--Yevick closure, thus extending to arbitrary odd dimension the solution for hard-sphere mixtures [J. L. Lebowitz, Phys.\ Rev.\ \textbf{133}, 895 (1964)]. Explicit evaluations for binary mixtures in five dimensions are performed. The results are compared with computer simulations and a good agreement is found.Comment: 16 pages, 8 figures; v2: slight change of notatio

The Autographa californica Nucleopolyhedrovirus IE-1 Protein Complex Has Two Modes of Specific DNA Binding

AbstractMissing contact footprinting with formic acid as a modifying reagent was used to examine specific IE-1 binding contacts to double-stranded oligonucleotides that contained either a consensus hr repeat sequence or a sequence from the pe38 promoter, which is down regulated by IE-1. The hr repeat sequences contain two consensus IE-1 binding motifs (IBMs) flanking a central EcoRI site that are oriented in opposite directions with respect to each other. IE-1 was found to contact regions including both IBMs. The bases footprinted in the top strand included the left IBM (IBM-A), whereas bases in the bottom strand were footprinted in a region that included IBM-B and part of IBM-A. When substitution mutations were introduced into either IBM, bases on both strands of the remaining IBM were strongly footprinted. As with the hr IBM-mutant constructs, bases footprinted in the pe38 promoter construct included both strands of the single IBM

Structure of hard-hypersphere fluids in odd dimensions

The structural properties of single component fluids of hard hyperspheres in odd space dimensionalities $d$ are studied with an analytical approximation method that generalizes the Rational Function Approximation earlier introduced in the study of hard-sphere fluids [S. B. Yuste and A. Santos, Phys. Rev. A {\bf 43}, 5418 (1991)]. The theory makes use of the exact form of the radial distribution function to first order in density and extends it to finite density by assuming a rational form for a function defined in Laplace space, the coefficients being determined by simple physical requirements. Fourier transform in terms of reverse Bessel polynomials constitute the mathematical framework of this approximation, from which an analytical expression for the static structure factor is obtained. In its most elementary form, the method recovers the solution of the Percus-Yevick closure to the Ornstein-Zernike equation for hyperspheres at odd dimension. The present formalism allows one to go beyond by yielding solutions with thermodynamic consistency between the virial and compressibility routes to any desired equation of state. Excellent agreement with available computer simulation data at $d=5$ and $d=7$ is obtained. As a byproduct of this study, an exact and explicit polynomial expression for the intersection volume of two identical hyperspheres in arbitrary odd dimensions is given.Comment: 18 pages, 7 figures; v2: new references added plus minor changes; to be published in PR

Thermo-statistical description of gas mixtures from space partitions

The new mathematical framework based on the free energy of pure classical fluids presented in [R. D. Rohrmann, Physica A 347, 221 (2005)] is extended to multi-component systems to determine thermodynamic and structural properties of chemically complex fluids. Presently, the theory focuses on $D$-dimensional mixtures in the low-density limit (packing factor $\eta < 0.01$). The formalism combines the free-energy minimization technique with space partitions that assign an available volume $v$ to each particle. $v$ is related to the closeness of the nearest neighbor and provides an useful tool to evaluate the perturbations experimented by particles in a fluid. The theory shows a close relationship between statistical geometry and statistical mechanics. New, unconventional thermodynamic variables and mathematical identities are derived as a result of the space division. Thermodynamic potentials $\mu_{il}$, conjugate variable of the populations $N_{il}$ of particles class $i$ with the nearest neighbors of class $l$ are defined and their relationships with the usual chemical potentials $\mu_i$ are established. Systems of hard spheres are treated as illustrative examples and their thermodynamics functions are derived analytically. The low-density expressions obtained agree nicely with those of scaled-particle theory and Percus-Yevick approximation. Several pair distribution functions are introduced and evaluated. Analytical expressions are also presented for hard spheres with attractive forces due to K\^ac-tails and square-well potentials. Finally, we derive general chemical equilibrium conditions.Comment: 14 pages, 8 figures. Accepted for publication in Physical Review

Loneliness is adversely associated with physical and mental health and lifestyle factors: Results from a Swiss national survey.

Loneliness is a common, emotionally distressing experience and is associated with adverse physical and mental health and an unhealthy lifestyle. Nevertheless, little is known about the prevalence of loneliness in different age groups in Switzerland. Furthermore, the existing evidence about age and gender as potential effect modifiers of the associations between loneliness, physical and mental health and lifestyle characteristics warrants further investigation. Thus, the aim of the study was to examine the prevalence of loneliness among adults in Switzerland and to assess the associations of loneliness with several physical and mental health and behavioral factors, as well as to assess the modifying effect of sex and age. Data from 20,007 participants of the cross-sectional population-based Swiss Health Survey 2012 (SHS) were analyzed. Logistic regression analyses were used to assess associations of loneliness with physical and mental health or lifestyle characteristics (e.g. diabetes, depression, physical activity). Wald tests were used to test for interactions. Loneliness was distributed in a slight U-shaped form from 15 to 75+ year olds, with 64.1% of participants who had never felt lonely. Lonely individuals were more often affected by physical and mental health problems, such as self-reported chronic diseases (Odds ratio [OR] 1.41, 95% confidence interval [CI] 1.30-1.54), high cholesterol levels (OR 1.31, 95% CI 1.18-1.45), diabetes (OR 1.40, 95% CI 1.16-1.67), moderate and high psychological distress (OR 3.74, 95% CI 3.37-4.16), depression (OR 2.78, 95% CI 2.22-3.48) and impaired self-perceived health (OR 1.94, 95% CI 1.74-2.16). Loneliness was significantly associated with most lifestyle factors (e.g. smoking; OR 1.13, 95% 1.05-1.23). Age, but not sex, moderated loneliness' association with several variables. Loneliness is associated with poorer physical and mental health and unhealthy lifestyle, modified by age, but not by sex. Our findings illustrate the importance of considering loneliness for physical and mental health and lifestyle factors, not only in older and younger, but also in middle-aged adults. Longitudinal studies are needed in Switzerland to elucidate the causal relationships of these associations

Evolution of white dwarf stars with high-metallicity progenitors: the role of 22Ne diffusion

Motivated by the strong discrepancy between the main sequence turn-off age and the white dwarf cooling age in the metal-rich open cluster NGC 6791, we compute a grid of white dwarf evolutionary sequences that incorporates for the first time the energy released by the processes of 22Ne sedimentation and of carbon/oxygen phase separation upon crystallization. The grid covers the mass range from 0.52 to 1.0 Msun, and it is appropriate for the study of white dwarfs in metal-rich clusters. The evolutionary calculations are based on a detailed and self-consistent treatment of the energy released from these two processes, as well as on the employment of realistic carbon/oxygen profiles, of relevance for an accurate evaluation of the energy released by carbon/oxygen phase separation. We find that 22Ne sedimentation strongly delays the cooling rate of white dwarfs stemming from progenitors with high metallicities at moderate luminosities, whilst carbon/oxygen phase separation adds considerable delays at low luminosities. Cooling times are sensitive to possible uncertainties in the actual value of the diffusion coefficient of 22Ne. Changing the diffusion coefficient by a factor of 2, leads to maximum age differences of approx. 8-20% depending on the stellar mass. We find that the magnitude of the delays resulting from chemical changes in the core is consistent with the slow down in the white dwarf cooling rate that is required to solve the age discrepancy in NGC 6791.Comment: 10 pages, 6 figures, to be published in The Astrophysical Journa

Evolution of white dwarf stars with high-metallicity progenitors: The role of 22Ne diffusion

Motivated by the strong discrepancy between the main-sequence turnoff age and the white dwarf cooling age in the metal-rich open cluster NGC 6791, we compute a grid of white dwarf evolutionary sequences that incorporates for the first time the energy released by the processes of 22Ne sedimentation and of carbon/oxygen phase separation upon crystallization. The grid covers the mass range from 0.52 to 1.0M⊙, and is appropriate for the study of white dwarfs in metal-rich clusters. The evolutionary calculations are based on a detailed and self-consistent treatment of the energy released from these two processes, as well as on the employment of realistic carbon/oxygen profiles, of relevance for an accurate evaluation of the energy released by carbon/oxygen phase separation. We find that 22Ne sedimentation strongly delays the cooling rate of white dwarfs stemming from progenitors with high metallicities at moderate luminosities, while carbon/oxygen phase separation adds considerable delays at lowluminosities. Cooling times are sensitive to possible uncertainties in the actual value of the diffusion coefficient of 22Ne. Changing the diffusion coefficient by a factor of 2 leads to maximum age differences of ≈8%-20% depending on the stellar mass. We find that the magnitude of the delays resulting from chemical changes in the core is consistent with the slowdown in the white dwarf cooling rate that is required to solve the age discrepancy in NGC 6791.Facultad de Ciencias Astronómicas y Geofísica

Virial series for fluids of hard hyperspheres in odd dimensions

A recently derived method [R. D. Rohrmann and A. Santos, Phys. Rev. E. {\bf 76}, 051202 (2007)] to obtain the exact solution of the Percus-Yevick equation for a fluid of hard spheres in (odd) $d$ dimensions is used to investigate the convergence properties of the resulting virial series. This is done both for the virial and compressibility routes, in which the virial coefficients $B_j$ are expressed in terms of the solution of a set of $(d-1)/2$ coupled algebraic equations which become nonlinear for $d \geq 5$. Results have been derived up to $d=13$. A confirmation of the alternating character of the series for $d\geq 5$, due to the existence of a branch point on the negative real axis, is found and the radius of convergence is explicitly determined for each dimension. The resulting scaled density per dimension $2 \eta^{1/d}$, where $\eta$ is the packing fraction, is wholly consistent with the limiting value of 1 for $d \to \infty$. Finally, the values for $B_j$ predicted by the virial and compressibility routes in the Percus-Yevick approximation are compared with the known exact values [N. Clisby and B. M. McCoy, J. Stat. Phys. {\bf 122}, 15 (2006)]Comment: 9 pages, 6 figure

Gender balance in ECEC : why is there s little progres?

Social attitudes about male participation in the upbringing of children have changed considerably over the past few decades. Men are now seen as important for children’s development and learning. Research from many countries worldwide shows that in early childhood care and education (ECEC), male workers are welcomed by female colleagues and parents. In the last two decades there have been initiatives for more men in ECEC in several European countries. Nevertheless the proportion of male workers ECEC remains low worldwide. This article questions the persisting gender imbalance in ECEC and analyzes ambivalences regarding more men in the field. Based on recent gender theory, efforts and limits of strategies for more male students and workers in ECEC in Belgium, Norway and Germany are discussed. It is concluded that deeply held gendered attitudes and practices in the field of care and educational work with young children have to be put into question. More space in ECEC for embodied subjectivities is needed to overcome essentialist conceptions of differences between body and mind, women and men