Nonlinear Galactic Dynamos and the Magnetic Pitch Angle

Pitch angles $p$ of the large-scale magnetic fields $\overline{\bf{\it{B}}}$ of spiral galaxies have previously been inferred from observations to be systematically larger in magnitude than predicted by standard mean-field dynamo theory. This discrepancy is more pronounced if dynamo growth has saturated, which is reasonable to assume given that such fields are generally inferred to be close to energy equipartition with the interstellar turbulence. This 'pitch angle problem' is explored using local numerical mean-field dynamo solutions as well as asymptotic analytical solutions. It is first shown that solutions in the saturated or kinematic regimes depend on only five dynamo parameters, two of which are tightly constrained by observations of galaxy rotation curves. The remaining 3-dimensional (dimensionless) parameter space can be constrained to some extent using theoretical arguments. Predicted values of $|p|$ can be as large as $\sim40^\circ$, which is similar to the largest values inferred from observations, but only for a small and non-standard region of parameter space. We argue, based on independent evidence, that such non-standard parameter values are plausible. However, these values are located toward the boundary of the allowed parameter space, suggesting that additional physical effects may need to be incorporated. We therefore suggest possible directions for extending the basic model considered.Comment: 11 pages, 5 figures, 1 table, edited to match ApJ versio

A renormalization approach for the 2D Anderson model at the band edge: Scaling of the localization volume

We study the localization volumes $V$ (participation ratio) of electronic wave functions in the 2d-Anderson model with diagonal disorder. Using a renormalization procedure, we show that at the band edges, i.e. for energies $E\approx \pm 4$, $V$ is inversely proportional to the variance \var of the site potentials. Using scaling arguments, we show that in the neighborhood of $E=\pm 4$, $V$ scales as V=\var^{-1}g((4-\ve E\ve)/\var) with the scaling function $g(x)$. Numerical simulations confirm this scaling ansatz

Pore opening effects and transport diffusion in the Knudsen regime in comparison to self- (or tracer-) diffusion

We study molecular diffusion in linear nanopores with different types of roughness in the so-called Knudsen regime. Knudsen diffusion represents the limiting case of molecular diffusion in pores, where mutual encounters of the molecules within the free pore space may be neglected and the time of flight between subsequent collisions with the pore walls significantly exceeds the interaction time between the pore wall and the molecules. We present an extension of a commonly used procedure to calculate transport diffusion coefficients. Our results show that using this extension, the coefficients of self- and transport diffusion in the Knudsen regime are equal for all regarded systems, which improves previous literature data.Comment: 5 pages, 7 figure

Entry, Multinational Firms, and Exchange Rate Volatility

Recent discussions of exchange rate determination have emphasized the possible role of foreign direct investment in influencing exchange rate behavior. Yet, there are few existing models of multinational enterprises (MNEs) and endogenous exchange rates. This paper demonstrates that the entry decisions of MNEs can influence the volatility of the real exchange rate in countries were there are significant costs involved in maintaining production facilities, even when prices are perfectly flexible. For empirically plausible parameters, MNE activity can make the exchange rate much more volatile than relative consumption.exchange rate volatility, foreign direct investment, market entry

Electron muon identification by atmospheric shower and electron beam in a new concept of an EAS detector

We present results demonstrating the time resolution and $\mu$/e separation capabilities with a new concept of an EAS detector capable for measurements of cosmic rays arriving with large zenith angles. This kind of detector has been designed to be a part of a large area (several square kilometers) surface array designed to measure Ultra High Energy (10-200 PeV) $\tau$ neutrinos using the Earth-skimming technique. A criteria to identify electron-gammas is also shown and the particle identification capability is tested by measurements in coincidence with the KASKADE-GRANDE experiment in Karlsruhe, Germany.Comment: accepted by Astrophysical Journal on January 12 2015, 16 pages 3 Figure

The Relationship Between Final Grades and Tutoring Methods of At-risk College Freshmen

Without academic intervention, such as tutoring, at-risk students may not pass their courses. This study examined differences between the final grades of at-risk students and tutoring methods, such as self-determined tutoring, academic advisor scheduled tutoring, group tutoring, one-to-one tutoring, peer tutoring, and professional tutoring. This study drew from cognitive learning theory and humanistic theory for its conceptual framework. A quantitative, ex post facto research design was used. Archived data supplied by the Registrar\u27s Office and the Academic Enrichment Coordinator included records of 95 male and female students conditionally enrolled at Methodist University in the Academic Enrichment Program during the 2007 to 2009 academic years. The results of an independent samples t test determined there was a significant difference between final grades of students who had self-determined tutoring compared to those who had academic advisor determined tutoring. Results of a one-way analysis of variance determined there were significant differences in final grades of students who received group tutoring compared to one-to-one tutoring and peer tutoring compared to professional tutoring. The preliminary results raised questions of the importance of tutor status in a group or one-to-one setting. A post hoc analysis using a paired-samples t test revealed a statistically significant difference in final grades of students in group settings but not in one-to-one settings. The results of this study offer the potential for positive social change to those in higher education by advancing the understanding of how to support and provide intervention programs, such as tutoring for at-risk students, in order to reduce their risk of academic failure during college

Exploring Factors Influencing Suicidal Behavior: An Investigation into Automatic Determinants of Capability Factors

This study investigated the associations between non-suicidal self-injury (NSSI), impulsivity, automatic associations with pain, and their combined impact on self-reported capability. The research hypotheses were tested using a sample of 226 participants (182 women, 40 men, and 4 individuals identifying outside the gender binary) recruited from the Department of Psychology participant pool at the University of Tennessee. An Implicit Association Test (IAT) was employed to measure automatic associations between pain/relief and good/bad. Three self-report questionnaires were also administered, namely the Inventory of Statements about Self-Injury (ISAS) to assess NSSI history, the Acquired Capability for Self-Harm (ACSS) to measure self-reported capability for self-harm and pain endurance, and the SUPPS-P Impulsive Behavior Scale to evaluate impulsivity. Correlation analyses and multiple regression were performed to examine the relationships between variables and test the research hypotheses. The results indicated that participants with a history of NSSI did not exhibit weakened pain-bad automatic associations (r = .06, p = .40), contrary to Hypothesis 1. Furthermore, Hypothesis 2, which predicted that weakened pain-bad automatic associations would predict higher levels of self-reported capability, was not supported. Instead, IAT scores showed a weak positive correlation with ACS scores (r = .13, p = .053). In testing Hypothesis 3, it was found that both SUPPS-P scores (a measure of impulsivity) and IAT scores independently predicted ACS scores. However, no significant interaction effect was observed. These findings contribute to the understanding of the complex relationships between NSSI, impulsivity, automatic associations with pain, and self-reported capability. Future research should continue exploring additional factors and mechanisms that may further elucidate these associations and enhance our understanding of self-harm and related behaviors

Franck-Condon factors and observed band strength distribution in the vibrational structure of the Ag_2 D-X band system

Potential curves for the X_1Σ_g^+ and D_1Σ_u^+ states of three diatomic silver isotopomers, ^(107)Ag_2, ^(107)Ag^(109)Ag and ^(109)Ag_2, were determined from the best available molecular constants by the Rydberg-Klein-Rees method. From these potentials, Franck-Condon factors and band-origin wave numbers were computed, and the reliability of the obtained values was verified by comparison with the observed band strength distribution and the measured band origin positions in a previously recorded D-X spectrum. The ratios of the Franck-Condon factors to those of corresponding isotopic bands were found to be very close to unity, revealing only a very small isotopic effect on the Franck Condon factors of Ag_2 D-X bands. The isotopic shifts of the calculated band origins agree well with previously measured displacements of band heads