Dynamical AC study of the critical behavior in Heisenberg spin glasses

We present some numerical results for the Heisenberg spin-glass model with Gaussian interactions, in a three dimensional cubic lattice. We measure the AC susceptibility as a function of temperature and determine an apparent finite temperature transition which is compatible with the chiral-glass temperature transition for this model. The relaxation time diverges like a power law $\tau\sim (T-T_c)^{-z\nu}$ with $T_c=0.19(4)$ and $z\nu=5.0(5)$. Although our data indicates that the spin-glass transition occurs at the same temperature as the chiral glass transition, we cannot exclude the possibility of a chiral-spin coupling scenario for the lowest frequencies investigated.Comment: 7 pages, 4 figure

A Viable Flavor Model for Quarks and Leptons in RS with T' Family Symmetry

We propose a Randall-Sundrum model with a bulk family symmetry based on the double tetrahedral group, T', which generates the tri-bimaximal neutrino mixing pattern and a realistic CKM matrix. The T' symmetry forbids tree-level flavor-changing-neutral-currents in both the quark and lepton sectors, as different generations of fermions are unified into multiplets of T'. This results in a low first KK mass scale and thus the model can be tested at collider experiments.Comment: 4 pages; based on talk presented at the 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions (SUSY09), Boston, MA, June 5-10, 200

Decentralization and local public services in Ghana: Do geography and ethnic diversity matter?

"This paper explores disparities in local public service provision between decentralized districts in Ghana using district- and household-level data. The empirical results show that districts' geographic locations play a major role in shaping disparities in access to local public services in Ghana. Most importantly, the findings suggest that ethnic diversity has significant negative impact in determining access to local public services, including drinking water. This negative impact is significantly higher in rural areas. However, the negative impact of ethnic diversity in access to local public services (drinking water) decreases as average literacy level increases. The paper relates the results to literature and discusses policy implications of main findings." from authors' abstractDecentralization, Access to public services, Ethnic diversity, Geography, Development strategies,

The Demographics of Georgia IV: Hispanic Immigration Economic Policy Issues - Brief

This report analyzes the economic policy issues in education, health care, the labor market, financial services and the fiscal impact arising from the large increase in Hispanic immigration in Georgia. FRC Brief 12

The Demographics of Georgia IV: Hispanic Immigration Economic Policy Issues

This report analyzes the economic policy issues in education, health care, the labor market, financial services and the fiscal impact arising from the large increase in Hispanic immigration in Georgia. FRC Report 12

Colliding clusters and dark matter self-interactions

When a dark matter halo moves through a background of dark matter particles, self-interactions can lead to both deceleration and evaporation of the halo and thus shift its centroid relative to the collisionless stars and galaxies. We study the magnitude and time evolution of this shift for two classes of dark matter self-interactions, viz. frequent self-interactions with small momentum transfer (e.g. due to long-range interactions) and rare self-interactions with large momentum transfer (e.g. contact interactions), and find important differences between the two cases. We find that neither effect can be strong enough to completely separate the dark matter halo from the galaxies, if we impose conservative bounds on the self-interaction cross-section. The majority of both populations remain bound to the same gravitational potential and the peaks of their distributions are therefore always coincident. Consequently any apparent separation is mainly due to particles which are leaving the gravitational potential, so will be largest shortly after the collision but not observable in evolved systems. Nevertheless the fraction of collisions with large momentum transfer is an important characteristic of self-interactions, which can potentially be extracted from observational data and provide an important clue as to the nature of dark matter.Comment: 13 pages + appendices, 8 figures, v2: minor corrections, references added - matches published versio

Thermodynamic reaction control of nucleoside phosphorolysis

Nucleoside analogs represent a class of important drugs for cancer and antiviral treatments. Nucleoside phosphorylases (NPases) catalyze the phosphorolysis of nucleosides and are widely employed for the synthesis of pentose‐1‐phosphates and nucleoside analogs, which are difficult to access via conventional synthetic methods. However, for the vast majority of nucleosides, it has been observed that either no or incomplete conversion of the starting materials is achieved in NPase‐catalyzed reactions. For some substrates, it has been shown that these reactions are reversible equilibrium reactions that adhere to the law of mass action. In this contribution, we broadly demonstrate that nucleoside phosphorolysis is a thermodynamically controlled endothermic reaction that proceeds to a reaction equilibrium dictated by the substrate‐specific equilibrium constant of phosphorolysis, irrespective of the type or amount of NPase used, as shown by several examples. Furthermore, we explored the temperature‐dependency of nucleoside phosphorolysis equilibrium states and provide the apparent transformed reaction enthalpy and apparent transformed reaction entropy for 24 nucleosides, confirming that these conversions are thermodynamically controlled endothermic reactions. This data allows calculation of the Gibbs free energy and, consequently, the equilibrium constant of phosphorolysis at any given reaction temperature. Overall, our investigations revealed that pyrimidine nucleosides are generally more susceptible to phosphorolysis than purine nucleosides. The data disclosed in this work allow the accurate prediction of phosphorolysis or transglycosylation yields for a range of pyrimidine and purine nucleosides and thus serve to empower further research in the field of nucleoside biocatalysis.DFG, 390540038, EXC 2008: UniSysCatTU Berlin, Open-Access-Mittel - 201