Accelerating Staggered Fermion Dynamics with the Rational Hybrid Monte Carlo (RHMC) Algorithm

Improved staggered fermion formulations are a popular choice for lattice QCD calculations. Historically, the algorithm used for such calculations has been the inexact R algorithm, which has systematic errors that only vanish as the square of the integration step-size. We describe how the exact Rational Hybrid Monte Carlo (RHMC) algorithm may be used in this context, and show that for parameters corresponding to current state-of-the-art computations it leads to a factor of approximately seven decrease in cost as well as having no step-size errors.Comment: 4 pages, 2 figures, 1 tabl

Descriptions of new luperine genera and species from Mexico : with keys to related taxa (Coleoptera: Chrysomelidae: Galerucinae)

The section Scelidites ofthe subtribe Luperina is diagnosed and described. A key is provided to separate the genera within this section. Cyphotarsis Jacoby is reduced to a junior synonym of Metacoryna Jacoby. Microscelida, new genus, is erected to include Agelastica viridis Jacoby, Luperus subcostatus Jacoby, Luperus subglabratus Jacoby, Scelidopsis violacea Jacoby, and seven newly described species. A key and diagnoses are provided to enable recognition of each species within this new genus. Scelidacne, new genus, is erected to include a single newly described species

The Western North American Genus Androlyperus Crotch, 1873 (Coleoptera: Chrysomelidae: Galerucinae)

The five previously known species of Androlyperus are redescribed and diagnosed. Androlyperus nataliae n. sp. is described from the Baja California Peninsula, Mexico. A taxonomic key is provided to facilitate species identification

The Rational Hybrid Monte Carlo Algorithm

The past few years have seen considerable progress in algorithmic development for the generation of gauge fields including the effects of dynamical fermions. The Rational Hybrid Monte Carlo (RHMC) algorithm, where Hybrid Monte Carlo is performed using a rational approximation in place the usual inverse quark matrix kernel is one of these developments. This algorithm has been found to be extremely beneficial in many areas of lattice QCD (chiral fermions, finite temperature, Wilson fermions etc.). We review the algorithm and some of these benefits, and we compare against other recent algorithm developements. We conclude with an update of the Berlin wall plot comparing costs of all popular fermion formulations.Comment: 15 pages. Proceedings from Lattice 200

Five years of social security reforms in the UK

The current Labour Government was elected in 1997 with few specific social security proposals. This paper argues that after five years, consistent trends in social security policy have emerged: there is a willingness to increase benefits; a “work-first” focus; increasing centrality for benefits that relate to ‘need’, which has involved expanded means-testing; a downgrading of contributory benefits; and, a desire to reduce poverty by redistributing to particular demographic groups. Many of these characteristics of Labour policy, such as the size of caseloads or aggregate expenditure, are yet to show up in various aggregate data, and we argue that this is probably due to various counter-balancing socio-economic changes since 1997. Looking forward, we discuss what the introduction of new forms of means-test might achieve. We also suggest that it might be considered odd that Labour has left Housing Benefit and Council Tax Benefit unreformed, especially since a good chance to reform them without significant cost or low-income losers, has been missed

Credit where it's due? An assessment of the new tax credits

In 2003: the government will introduce new tax credits to provide financial support for children and low-paid workers: the integrated child credit and the employment tax credit. The reform to support for children aims to unify existing payments in a way that provides a guaranteed stream of income for those with children, whether they are working or not. The credit for people in work will provide an income top-up for low earners - something that those without children have not benefited from before. The government has not announced the impact of the reforms on the public finances, but both will cost the exchequer money, so this Commentary considers the likely sums involved. We also examine whether the reforms look like fulfilling their stated aims: making work pay, relieving poverty and creating a new type of state support that is simpler and less intrusive for claimants