Simulated-tempering approach to spin-glass simulations

After developing an appropriate iteration procedure for the determination of the parameters, the method of simulated tempering has been successfully applied to the 2D Ising spin glass. The reduction of the slowing down is comparable to that of the multicanonical algorithm. Simulated tempering has, however, the advantages to allow full vectorization of the programs and to provide the canonical ensemble directly.Comment: 12 pages (LaTeX), 4 postscript figures, uufiles encoded, submitted to Physical Review

Gene finding in genetically isolated populations

The struggle to identify susceptibility genes for complex disorders has stimulated geneticists to develop new approaches. One approach that has gained considerable interest is to focus on genetically isolated populations rather than on the general population. There remains much controversy and theoretical debate over the feasibility and advantages of such populations, but recent results speak in favor of the feasibility of this approach, and will be reviewed here

FDI and productivity gains in developing countries: How to make sense of an inconclusive debate?

Policymakers seeFDI as amajor source for potential productivity gains, but the academic debateon its impact on developing countries is full of contradictions. This short noteinvestigates the impact of FDI on productivity using a meta-analysis of 74 of primary empirical studies published over 1983 –2013and dealing with 31 developing countries. We find a positive and economically important productivity spilloverfrom FDI

FDI and productivity gains in developing countries: How to make sense of an inconclusive debate?

Policymakers seeFDI as amajor source for potential productivity gains, but the academic debateon its impact on developing countries is full of contradictions. This short noteinvestigates the impact of FDI on productivity using a meta-analysis of 74 of primary empirical studies published over 1983 –2013and dealing with 31 developing countries. We find a positive and economically important productivity spilloverfrom FDI

A Meta-Analysis of FDI and Productivity Spillovers in Developing Countries

This meta-analysis reviews the intrasector heterogeneity of productivity spillovers from foreign direct investment (FDI) in 31 developing countries through a larger more comprehensive data set. We investigate how the inconsistencies in the reported spillover findings are affected by publication bias, characteristics of the data, estimation techniques, and empirical specification, analyzing 1450 spillover estimates from 69 empirical studies published in 1986–2013. Our findings suggest that reported FDI spillover estimates are affected by publication bias. In combination with model misspecification of the primary studies, the bias overstates the genuine underlying meta-effect, but the meta-effect remains economically and statistically significant. Our results emphasize that spillovers and their sign largely depend systematically on specification characteristics of the primary studies and publication bias. Publication bias is not caused by “best practice” choices. Future research needs to cover more developing countries and to investigate not only whether spillovers occur, but also to explore inside the black box of how spillovers actually emerge

Observing FDI spillover transmission channels: evidence from firms in Uganda

We observe and analyse three intra-industry foreign direct investment (FDI) spillover transmission channels using unique firm-level data collected from on-site interviews and observations regarding domestic and foreign firms operating in Uganda in 2015. Our main results are: (1) the spillover effects mainly depend on the channel(s) by which they occur (the competition channel is most important while spillover benefits through the worker mobility and the imitation channels are less prevalent) and (2) both positive and negative spillover effects occur within the same channel and, moreover, effects differ by channel for the same case. These are novel and challenging findings that have not yet been recognised in theoretical and empirical research on FDI spillovers. Our results suggest that long-term pecuniary spillover effects are predominantly stimulated via the competition channel and show that only limited short-term and long-term technological spillover effects occur through the imitation and the movement of workers channels. These channels are not only less prevalent, but also appear to be constrained by competition-determined spillovers. We are confident that these directions for future research will have a high pay-off because, as shown by this exploratory fieldwork, a more complete picture of the spillover effects is reached when the channels are considered simultaneousl

The Heavy Quark Self-Energy in Nonrelativistic Lattice QCD

The heavy quark self-energy in nonrelativistic lattice QCD is calculated to $O(\alpha_s)$ in perturbation theory. An action which includes all spin-independent relativistic corrections to order $v^2$, where $v$ is the typical heavy quark velocity, and all spin-dependent corrections to order $v^4$ is used. The standard Wilson action and an improved multi-plaquette action are used for the gluons. Results for the mass renormalization, wavefunction renormalization, and energy shift are given; tadpole contributions are found to be large. A tadpole improvement scheme in which all link variables are rescaled by a mean-field factor is also studied. The effectiveness of this scheme in offsetting the large tadpole contributions to the heavy quark renormalization parameters is demonstrated.Comment: 28 pages, SLAC-PUB-598

Developing a phenomenological equation to predict yield strength from composition and microstructure in β processed Ti-6Al-4V

A constituent-based phenomenological equation to predict yield strength values from quantified measurements of the microstructure and composition of β processed Ti-6Al-4V alloy was developed via the integration of artificial neural networks and genetic algorithms. It is shown that the solid solution strengthening contributes the most to the yield strength (~80% of the value), while the intrinsic yield strength of the two phases and microstructure have lower effects (~10% for both terms). Similarities and differences between the proposed equation and the previously established phenomenological equation for the yield strength prediction of the α+β processed Ti-6Al-4V alloys are discussed. While the two equations are very similar in terms of the intrinsic yield strength of the two constituent phases, the solid solution strengthening terms and the ‘Hall-Petch’-like effect from the alpha lath, there is a pronounced difference in the role of the basketweave factor in strengthening. Finally, Monte Carlo simulations were applied to the proposed phenomenological equation to determine the effect of measurement uncertainties on the estimated yield strength values

Renormalization group improvement of the spectrum of Hydrogen-like atoms with massless fermions

We obtain the next-to-next-to-leading-log renormalization group improvement of the spectrum of Hydrogen-like atoms with massless fermions by using potential NRQED. These results can also be applied to the computation of the muonic Hydrogen spectrum where we are able to reproduce some known double logs at O(m\alpha^6). We compare with other formalisms dealing with log resummation available in the literature.Comment: 9 pages, LaTeX. Minor changes, note added, final versio

Two-Loop Static QCD Potential for General Colour State

In this letter, we extend the known results for the QCD potential between a static quark and its antiquark by computing the two-loop corrections to the colour-octet state.Comment: 7 page