Dynamical aspects of inextensible chains

In the present work the dynamics of a continuous inextensible chain is studied. The chain is regarded as a system of small particles subjected to constraints on their reciprocal distances. It is proposed a treatment of systems of this kind based on a set Langevin equations in which the noise is characterized by a non-gaussian probability distribution. The method is explained in the case of a freely hinged chain. In particular, the generating functional of the correlation functions of the relevant degrees of freedom which describe the conformations of this chain is derived. It is shown that in the continuous limit this generating functional coincides with a model of an inextensible chain previously discussed by one of the authors of this work. Next, the approach developed here is applied to a inextensible chain, called the freely jointed bar chain, in which the basic units are small extended objects. The generating functional of the freely jointed bar chain is constructed. It is shown that it differs profoundly from that of the freely hinged chain. Despite the differences, it is verified that in the continuous limit both generating functionals coincide as it is expected.Comment: 15 pages, LaTeX 2e + various packages, 3 figures. The title has been changed and three references have been added. A large part of the manuscript has been rewritten to improve readability. Chapter 4 has been added. It contains the construction of the generating functional without the shish-kebab approximation and a new derivation of the continuous limit of the freely jointed bar chai

Specific heat of the ideal gas obeying the generalized exclusion statistics

We calculate the specific heat of the ideal gas obeying the generalized exclusion statistics (GES) in the continuum model and the tight binding model numerically. In the continuum model of 3-d space, the specific heat increases with statistical parameter at low temperature whereas it decreases with statistical parameter at high temperature. We find that the critical temperature normalized by $\mu_f$ (Fermi energy) is 0.290. The specific heat of 2-d space was known to be independent of $g$ in the continuum model, but it varies with $g$ drastically in the tight-binding model. From its unique behavior, identification of GES particles will be possible from the specific heat.Comment: 14 pages, 9 figures, to be published in Eur. Phys. J. B, References and figures added, typos corrected, one section removed and two sections merge

Cooling of Sr to high phase-space density by laser and sympathetic cooling in isotopic mixtures

Based on an experimental study of two-body and three-body collisions in ultracold strontium samples, a novel optical-sympathetic cooling method in isotopic mixtures is demonstrated. Without evaporative cooling, a phase-space density of $6\times10^{-2}$ is obtained with a high spatial density that should allow to overcome the difficulties encountered so far to reach quantum degeneracy for Sr atoms.Comment: 5 pages, 4 figure

Lorentz symmetry breaking in the noncommutative Wess-Zumino model: One loop corrections

In this paper we deal with the issue of Lorentz symmetry breaking in quantum field theories formulated in a non-commutative space-time. We show that, unlike in some recente analysis of quantum gravity effects, supersymmetry does not protect the theory from the large Lorentz violating effects arising from the loop corrections. We take advantage of the non-commutative Wess-Zumino model to illustrate this point.Comment: 9 pages, revtex4. Corrected references. Version published in PR

Exploring the factors that influence the public health impact of changes to the traditional housing officer’s role : insights from a logic modelling approach

Background Complex interventions can be challenging to summarise and interpret. One approach to attempt to succinctly describe such complexity is through the development of a logic model. This study considers a complex intervention that aimed to widen the role and responsibilities of housing officers, through a neighbourhood-based system. Methods We developed a logic model using both primary and secondary data collection alongside expert opinion in order to understand the complex relationships between the intervention being delivered and the actual and potential outcomes. Development of the model was supported by a range of data generation methods, including a scoping review of the literature, telephone survey with housing tenants, in-depth interviews with tenants and housing staff, and workshops with key stakeholders to help to develop and then validate the model. Results Our logic model highlights the key role of interpersonal relationships in building coherent neighbourhoods through intervention success and tenant satisfaction. We developed our initial model from analysis of documents relating to the intervention, along with wider literature, which detailed the policy context, theoretical approach and the expected outcomes. Conclusions The process of defining our final logic model generated insights that would not have emerged from a more narrative synthesis of secondary and primary data. The most important of these was a clear message about the central role of relationships between neighbourhood officers and tenants. In similar interventions, thought needs to be given on how a relationship can be built between a tenant and a neighbourhood officer

From interacting particle systems to random matrices

In this contribution we consider stochastic growth models in the Kardar-Parisi-Zhang universality class in 1+1 dimension. We discuss the large time distribution and processes and their dependence on the class on initial condition. This means that the scaling exponents do not uniquely determine the large time surface statistics, but one has to further divide into subclasses. Some of the fluctuation laws were first discovered in random matrix models. Moreover, the limit process for curved limit shape turned out to show up in a dynamical version of hermitian random matrices, but this analogy does not extend to the case of symmetric matrices. Therefore the connections between growth models and random matrices is only partial.Comment: 18 pages, 8 figures; Contribution to StatPhys24 special issue; minor corrections in scaling of section 2.

Additive benefit of higher testosterone levels and vitamin D plus calcium supplementation in regard to fall risk reduction among older men and women

Summary: Higher physiologic testosterone levels among community dwelling older men and women may protect against falls, and this benefit may be further increased among those taking additional vitamin D plus calcium. Introduction: The aim of this study is to investigate sex hormone levels and fall risk in older men and women. Methods: One hundred and ninety-nine men and 246 women age 65+ living at home were followed for 3years after baseline assessment of sex hormones. Analyses controlled for several covariates, including baseline 25-hydroxyvitamin D, sex hormone binding globulin, and vitamin D plus calcium treatment (vitD+cal). Results: Compared to the lowest quartile, men and women in the highest quartile of total testosterone had a decreased odds of falling (men: OR = 0.22; 95% CI [0.07,0.72]/ women: OR = 0.34; 95% CI [0.14,0.83]); if those individuals also took vitD+cal, the fall reduction was enhanced (men: OR = 0.16; 95% CI [0.03,0.90] / women: OR = 0.15; 95% CI [0.04,0.57]). Similarly, women in the top quartile of dihydroepiandrosterone sulfate (DHEA-S) had a lower risk of falling (OR = 0.39; 95% CI [0.16,0.93]). Other sex hormones and SHBG did not predict falling in men or women. Conclusions: Higher testosterone levels in both genders and higher DHEA-S levels in women predicted a more than 60% lower risk of falling. With vitD+cal, the anti-fall benefit of higher physiologic testosterone levels is enhanced from 78% to 84% among men and from 66% to 85% among wome

Domino tilings and the six-vertex model at its free fermion point

At the free-fermion point, the six-vertex model with domain wall boundary conditions (DWBC) can be related to the Aztec diamond, a domino tiling problem. We study the mapping on the level of complete statistics for general domains and boundary conditions. This is obtained by associating to both models a set of non-intersecting lines in the Lindstroem-Gessel-Viennot (LGV) scheme. One of the consequence for DWBC is that the boundaries of the ordered phases are described by the Airy process in the thermodynamic limit.Comment: 14 pages, 8 figure

Intermixture of extended edge and localized bulk energy levels in macroscopic Hall systems

We study the spectrum of a random Schroedinger operator for an electron submitted to a magnetic field in a finite but macroscopic two dimensional system of linear dimensions equal to L. The y direction is periodic and in the x direction the electron is confined by two smooth increasing boundary potentials. The eigenvalues of the Hamiltonian are classified according to their associated quantum mechanical current in the y direction. Here we look at an interval of energies inside the first Landau band of the random operator for the infinite plane. In this energy interval, with large probability, there exist O(L) eigenvalues with positive or negative currents of O(1). Between each of these there exist O(L^2) eigenvalues with infinitesimal current O(exp(-cB(log L)^2)). We explain what is the relevance of this analysis to the integer quantum Hall effect.Comment: 29 pages, no figure