Universality of ac-conduction in anisotropic disordered systems: An effective medium approximation study

Anisotropic disordered system are studied in this work within the random barrier model. In such systems the transition probabilities in different directions have different probability density functions. The frequency-dependent conductivity at low temperatures is obtained using an effective medium approximation. It is shown that the isotropic universal ac-conduction law, $\sigma \ln \sigma=u$, is recovered if properly scaled conductivity ($\sigma$) and frequency ($u$) variables are used.Comment: 5 pages, no figures, final form (with corrected equations

Birthing Washington: Objects, memory, and the creation of a national monument

The National Park Service\u27s (NPS) George Washington Birthplace National Monument has commemorated Washington and his life for over seventy-five years. For much of that time, the NPS worked closely with the memorial\u27s progenitors, the \u27ladies\u27 of the Wakefield National Memorial Association (WNMA). Although equally committed to the preservation of Washington\u27s legacy, these two groups clashed over questions of authenticity, historical authority, and proper commemorative strategy. This dissertation explores their relationship for what it reveals about the rise of public history in this country and Federal involvement therein.;We witness at Washington\u27s birthplace a collision between old-order Colonial Revivalists (led for a time by renowned preservationist Louise DuPont Crowninshield) and a new generation of male museum professionals under NPS Director Horace Albright. The WNMA erected a \u27replica\u27 Memorial House atop a site marked in 1815 by George Washington Parke Custis. The NPS determined the Memorial House was neither properly located nor an authentic replica. Still, the WNMA defended the building\u27s veracity. Birthing Washington argues that the two groups defined authenticity differently and that those definitions reflected not only gendered difference and political motivation, but also new ways of constituting historical knowledge available during the first half of the twentieth century.;What began as a confused argument about authenticity manifested publicly in decisions made about what kind of objects to display at Washington\u27s birthplace and how to display them. The WNMA preferred charming interiors to the NPS\u27s stark historical realism. Both methods created considerable interpretive possibilities and limitations. Buoyed by national trends, historical realism prevailed at Washington\u27s birthplace. But \u27living history\u27 only created new interpretive dilemmas by failing to grapple with old questions about authenticity perpetuated by the Memorial House\u27s ongoing presence. I conclude that sites of public memory cannot help but reify the historical currents of their formative moments and, for that reason, the NPS must challenge itself to interpret the history of commemoration at sites like Washington\u27s birthplace

The Role of Neuronal DNA Methyltransferase 1 in Energy Homeostasis and Obesity

Obesity is a grave disease that is increasing in global prevalence. Aberrant neuronal DNA methylation patterns have been implicated in the promotion of obesity development, but the role of neuronal DNA methyltransferases (Dnmts; enzymes that catalyze DNA methylation) in energy balance remains poorly understood. We investigated the role of neuronal Dnmt1 in normal energy regulation and obesity development using a novel Dnmt1 knockout mouse model, Dnmt1fl/fl Synapsin1Cre (ND1KO), which specifically deletes Dnmt1 in neurons. ND1KO and fl/fl control littermates were fedeither a standard chow diet or a high fat diet (HFD). We conducted a deep analysis to characterize both peripheral and central aspects of the ND1KO phenotype. We found that neuronal Dnmt1 deficiency reduced adiposity in chow-fed mice and attenuated obesity in HFD-fed male mice. ND1KO male mice had reduced food intake and increased energy expenditure on the HFD. Furthermore, these mice had improved insulin sensitivity as measured by an insulin tolerance test. HFD-fed ND1KO mice had smaller fat pads and an upregulation of thermogenic genes in brown adipose tissue. These data suggest that neuronal Dnmt1 deletion increased diet-induced thermogenesis, which may explain the lean phenotype in HFD-fed ND1KO mice. Interestingly, we found that ND1KO male mice had elevated estrogen receptor-α gene expression in the hypothalamus, which previously has been shown to control body weight. Immunohistochemistry experiments revealed that estrogen receptor-α (ERα) protein expression was upregulated in the dorsomedial region of the VMH (VMHdm), a region which may mediate the central effect of leptin. Finally, we tested whether ND1KO mice had reduced methylation of the ERα gene promoter, which might explain the ERα upregulation. Neuronal Dnmt1 deficiency decreased methylation at two CpG sites on Exon A in chow-fed mice. Collectively, these data suggest that neuronal Dnmt1 regulates energy homeostasis through pathways controlling food intake and energy expenditure, and that ERα in the VMHdm may mediate these effects

Mechanical Properties of Flush-Riveted Joints

The strength of representative types of flush-riveted joints has been determined by testing 865 single-shearing, double-shearing, and tensile specimens representing 7 types of rivet and 18 types of joint. The results, presented in graphic form, show the stress at failure, type of failure, and d/t ratio. In general, 'dimpled' joints were appreciably stronger than countersunk or protruding-head joints, but their strength was greatly influenced by constructional details. The optimum d/t ratios have been determined for the several kinds of joints. Photomacrographs of each type show constructional details and, in several instances, cracks in the sheet

Rphylopars: fast multivariate phylogenetic comparative methods for missing data and within-species variation

Over the past several years, phylogenetic comparative studies have increasingly approached trait evolution in a multivariate context, with a number of taxa that continues to rise dramatically. Recent methods for phylogenetic comparative studies have provided ways to incorporate measurement error and to address computational challenges. However, missing data remain a particularly common problem, in which data are unavailable for some but not all traits of interest for a given species (or individual), leaving researchers with the choice between omitting observations or utilizing imputation-based approaches. Here, we introduce an r implementation of PhyloPars, a tool for phylogenetic imputation of missing data and estimation of trait covariance across species (phylogenetic covariance) and within species (phenotypic covariance). Rphylopars provides expanded capabilities over the original PhyloPars interface including a fast linear-time algorithm, thus allowing for extremely large data sets (which were previously computationally infeasible) to be analysed in seconds or minutes rather than hours. In addition to providing fast and computationally efficient implementations, we introduce in Rphylopars methods to estimate macroevolutionary parameters under alternative evolutionary models (e.g. Early-Burst, multivariate Ornstein-Uhlenbeck). By providing fast and computationally efficient methods with flexible options for various phylogenetic comparative approaches, Rphylopars expands the possibilities for researchers to analyse large and complex data with missing observations, within-species variation and deviations from Brownian motion

THE RELATION BETWEEN THE NUMBER OF REPETITIONS AND THE RELATIVE LOAD IN STRENGTH TRAINING

It was the aim of this study to determine the relationship between the number of repetitions that can be lifted at a range of percentages of the 1RM load in leg curl and bench press. Comparisons were made between males and females, and between long distance runners and sprinters. Findings suggest that this relationship is different between the two types of exercise. No differences were found between males and females. When working with highly trained athletes in bench press it is recommended that different regression equations are employed when studying sprint trained or endurance trained athletes

Spectral Representation for the Effective Macroscopic Response of a Polycrystal: Application to Third-Order Nonlinear Susceptibility

Erratum: In our paper, we show that the spectral representation for isotropic two-component composites also applies to uniaxial polycrystals. We have learned that this result was, in fact, first conjectured by G.W. Milton. While our derivation is more detailed, our result for the spectral function is the same as Milton's. We very much regret not having been aware of this work at the time of writing our paper. Original abstract: We extend the spectral theory used for the calculation of the effective linear response functions of composites to the case of a polycrystalline material with uniaxially anisotropic microscopic symmetry. As an application, we combine these results with a nonlinear decoupling approximation as modified by Ma et al., to calculate the third-order nonlinear optical susceptibility of a uniaxial polycrystal, assuming that the effective dielectric function of the polycrystal can be calculated within the effective-medium approximation.Comment: v2 includes erratum and the original preprin