Localization properties of the anomalous diffusion phase x tμx ~ t^{\mu} in the directed trap model and in the Sinai diffusion with bias

We study the anomalous diffusion phase $x ~ t^{\mu}$ with $0<\mu<1$ which exists both in the Sinai diffusion at small bias, and in the related directed trap model presenting a large distribution of trapping time $p(\tau) \sim 1/\tau^{1+\mu}$. Our starting point is the Real Space Renormalization method in which the whole thermal packet is considered to be in the same renormalized valley at large time : this assumption is exact only in the limit $\mu \to 0$ and corresponds to the Golosov localization. For finite $\mu$, we thus generalize the usual RSRG method to allow for the spreading of the thermal packet over many renormalized valleys. Our construction allows to compute exact series expansions in $\mu$ of all observables : at order $\mu^n$, it is sufficient to consider a spreading of the thermal packet onto at most $(1+n)$ traps in each sample, and to average with the appropriate measure over the samples. For the directed trap model, we show explicitly up to order $\mu^2$ how to recover the diffusion front, the thermal width, and the localization parameter $Y_2$. We moreover compute the localization parameters $Y_k$ for arbitrary $k$, the correlation function of two particles, and the generating function of thermal cumulants. We then explain how these results apply to the Sinai diffusion with bias, by deriving the quantitative mapping between the large-scale renormalized descriptions of the two models.Comment: 33 pages, 3 eps figure

Can brewer-sponsored ‘drink responsibly’ warning message be effective without alcohol policies in Nigeria?

Alcohol availability, use and misuse and their related problems are rising in many parts of the African continent and this has been attributed to many factors such as non-existent or ineffective regulatory measures. In contemporary Nigeria, while a culture of intoxication is growing, there are no regulatory measures in the form of alcohol policies to reduce it. What exists is brewer-sponsored self-regulation. This paper therefore, critically analyses this self-imposed 'drink responsibly' warning message, arguing that because responsible drinking messages are strategically designed to serve the interest of alcohol industries, it cannot be effective. The paper further argues that because there are no definitions of standard drinks and where alcohol by volume (ABV) is scarcely inscribed on product labels of alcoholic beverages, such message will remain ineffective. Therefore, it recommends that an urgent step should be taken by the government to formulate and implement comprehensive evidence-based alcohol policies in Nigeria

Spherical Model in a Random Field

We investigate the properties of the Gibbs states and thermodynamic observables of the spherical model in a random field. We show that on the low-temperature critical line the magnetization of the model is not a self-averaging observable, but it self-averages conditionally. We also show that an arbitrarily weak homogeneous boundary field dominates over fluctuations of the random field once the model transits into a ferromagnetic phase. As a result, a homogeneous boundary field restores the conventional self-averaging of thermodynamic observables, like the magnetization and the susceptibility. We also investigate the effective field created at the sites of the lattice by the random field, and show that at the critical temperature of the spherical model the effective field undergoes a transition into a phase with long-range correlations $\sim r^{4-d}$.Comment: 29 page

Conductivity Due to Classical Phase Fluctuations in a Model For High-T_c Superconductors

We consider the real part of the conductivity, \sigma_1(\omega), arising from classical phase fluctuations in a model for high-T_c superconductors. We show that the frequency integral of that conductivity, \int_0^\infty \sigma_1 d\omega, is non-zero below the superconducting transition temperature $T_c$, provided there is some quenched disorder in the system. Furthermore, for a fixed amount of quenched disorder, this integral at low temperatures is proportional to the zero-temperature superfluid density, in agreement with experiment. We calculate \sigma_1(\omega) explicitly for a model of overdamped phase fluctuations.Comment: 4pages, 2figures, submitted to Phys.Rev.

Maternal periconceptional alcohol consumption and gastroschisis in the National Birth Defects Prevention Study, 1997–2011

Background: Gastroschisis is particularly prevalent among offspring of young women and has increased over recent decades. Although previous studies suggest that maternal alcohol consumption is associated with increased gastroschisis risk, none have explored whether maternal age modifies that association. Objective: The objective of the study was to evaluate associations between self-reported maternal periconceptional alcohol consumption (1 month prior through the third month after conception) and risk of gastroschisis among offspring, by maternal age. Methods: We used data from the National Birth Defects Prevention Study (NBDPS), a multi-site population-based case-control study. The analysis included 1450 gastroschisis cases and 11,829 unaffected liveborn controls delivered during 1997–2011 in ten US states. We estimated adjusted odds ratios (aOR) and 95% confidence intervals (CI) for the individual and joint effects of alcohol consumption and young maternal age at delivery (<25 years vs ≥25 years) on gastroschisis risk. We estimated the relative excess risk due to interaction (RERI) to quantify additive interaction. Results: Periconceptional alcohol consumption was common regardless of maternal age (women <25 years: cases 38.8%, controls 29.3%; women ≥25: cases 43.5%, controls 39.5%). Compared with women ≥25 years who did not consume alcohol, we observed increased risk of gastroschisis among women <25 years, with higher estimates among those who consumed alcohol (women <25 years who did not consume alcohol. aOR 5.90, 95% CI 4.89, 7.11; women <25 years who did consume alcohol: aOR 8.21, 95% CI 6.69, 10.07). Alcohol consumption among women ≥25 years was not associated with gastroschisis (aOR 1.12, 95% CI 0.88, 1.42). This suggests super-additive interaction between alcohol consumption and maternal age (RERI −2.19, 95% CI 1.02, 3.36). Conclusions: Periconceptional alcohol consumption may disproportionately increase risk of gastroschisis among young mothers. Our findings support public health recommendations to abstain from alcohol consumption during pregnancy

Double Inflation in Supergravity and the Large Scale Structure

The cosmological implication of a double inflation model with hybrid + new inflations in supergravity is studied. The hybrid inflation drives an inflaton for new inflation close to the origin through supergravity effects and new inflation naturally occurs. If the total e-fold number of new inflation is smaller than $\sim 60$, both inflations produce cosmologically relevant density fluctuations. Both cluster abundances and galaxy distributions provide strong constraints on the parameters in the double inflation model assuming $\Omega_0=1$ standard cold dark matter scenario. The future satellite experiments to measure the angular power spectrum of the cosmic microwave background will make a precise determination of the model parameters possible.Comment: 19 pages (RevTeX file

The Potts Fully Frustrated model: Thermodynamics, percolation and dynamics in 2 dimensions

We consider a Potts model diluted by fully frustrated Ising spins. The model corresponds to a fully frustrated Potts model with variables having an integer absolute value and a sign. This model presents precursor phenomena of a glass transition in the high-temperature region. We show that the onset of these phenomena can be related to a thermodynamic transition. Furthermore this transition can be mapped onto a percolation transition. We numerically study the phase diagram in 2 dimensions (2D) for this model with frustration and {\em without} disorder and we compare it to the phase diagram of $i)$ the model with frustration {\em and} disorder and of $ii)$ the ferromagnetic model. Introducing a parameter that connects the three models, we generalize the exact expression of the ferromagnetic Potts transition temperature in 2D to the other cases. Finally, we estimate the dynamic critical exponents related to the Potts order parameter and to the energy.Comment: 10 pages, 10 figures, new result

Effective Actions and Phase Fluctuations in d-wave Superconductors

We study effective actions for order parameter fluctuations at low temperature in layered d-wave superconductors such as the cuprates. The order parameter lives on the bonds of a square lattice and has two amplitude and two phase modes associated with it. The low frequency spectral weights for amplitude and relative phase fluctuations is determined and found to be subdominant to quasiparticle contributions. The Goldstone phase mode and its coupling to density fluctuations in charged systems is treated in a gauge-invariant manner. The Gaussian phase action is used to study both the $c$-axis Josephson plasmon and the more conventional in-plane plasmon in the cuprates. We go beyond the Gaussian theory by deriving a coarse-grained quantum XY model, which incorporates important cutoff effects overlooked in previous studies. A variational analysis of this effective model shows that in the cuprates, quantum effects of phase fluctuations are important in reducing the zero temperature superfluid stiffness, but thermal effects are small for $T << T_c$.Comment: Some numerical estimates corrected and figures changed. to appear in PRB, Sept.1 (2000

Density-functional embedding using a plane-wave basis

The constrained electron density method of embedding a Kohn-Sham system in a substrate system (first described by P. Cortona, Phys. Rev. B {\bf 44}, 8454 (1991) and T.A. Wesolowski and A. Warshel, J. Phys. Chem {\bf 97}, 8050 (1993)) is applied with a plane-wave basis and both local and non-local pseudopotentials. This method divides the electron density of the system into substrate and embedded electron densities, the sum of which is the electron density of the system of interest. Coupling between the substrate and embedded systems is achieved via approximate kinetic energy functionals. Bulk aluminium is examined as a test case for which there is a strong interaction between the substrate and embedded systems. A number of approximations to the kinetic-energy functional, both semi-local and non-local, are investigated. It is found that Kohn-Sham results can be well reproduced using a non-local kinetic energy functional, with the total energy accurate to better than 0.1 eV per atom and good agreement between the electron densities.Comment: 11 pages, 4 figure

Status of Vectorized Monte Carlo for Particle Transport Analysis

The conventional particle transport Monte Carlo algorithm is ill suited for modem vector supercomputers because the random nature of the particle transport process in the history based algorithm in hibits construction of vectors. An alterna tive, event-based algorithm is suitable for vectorization and has been used recently to achieve impressive gains in perfor mance on vector supercomputers. This re view describes the event-based algorithm and several variations of it Implementa tions of this algorithm for applications in particle transport are described, and their relative merits are discussed. The imple mentation of Monte Carlo methods on multiple vector parallel processors is con sidered, as is the potential of massively parallel processors for Monte Carlo par ticle transport simulations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67177/2/10.1177_109434208700100203.pd