First Order Bipolaronic Transition at Finite Temperature in the Holstein Model

We investigate the Holstein model by using the dynamical mean-field theory combined with the exact diagonalization method. Below a critical temperature Tcr, a coexistence of the polaronic and the bipolaronic solutions is found for the same value of the electron-phonon coupling $ in the range gc1(T)<g<gc2(T). In the coexistence region, the system shows a first order phase transition from the bipolaronic to the polaronic states as T decreases at T=Tp(<Tcr), where the double occupancy and the lattice fluctuation together with the anharmonicity of the effective ion potential change discontinuously without any symmetry breaking. The obtained bipolaronic transition seems to be consistent with the rattling transition in the beta-pyrochlore oxide KOs2O6.Comment: 5 pages, 5 figures, J. Phys. Soc. Jpn. 79 (2010) 09370

Watchdogs, Helpers or Protectors? – Internal Auditing in Malaysian Local Government

This paper examines internal auditor roles to support public governance in a developing country context, through interviews with chief audit executives across 17 Malaysian Local Government Authorities. Drawing on critical theory, the research shows that internal auditors seek to legitimise their position through compliance (watchdog) and performance (helper and protector) audits. At the micro level of practices, in performing these dual roles, internal auditors are not colonised by governance rules and managerial influence, but instead are enabled by them to perform communicative action. Nevertheless, this was undermined by financial and managerial capacity issues that are a challenge in developing countries

Child consent in South African law: Implications for researchers, service providers and policy-makers

Children under 18 are legal minors who, in South African law, are not fully capable of acting independently without assistance from parents/legal guardians. However, in recognition of the evolving capacity of children, there are exceptional circumstances where the law has granted minorsthe capacity to act independently. We describe legal norms for child consent to health-related interventions in South Africa, and argue that the South African Parliament has taken an inconsistent approach to: the capacity of children to consent; the persons able to consent when children do not have capacity; and restrictions on the autonomy of children or theirproxies to consent. In addition, the rationale for the differing age limitations, capacity requirements and public policy restrictions has not been specified. These inconsistencies make it difficult for stakeholders interacting with children to ensure that they act lawfully

Adult videogame consumption as individualised, episodic progress

Drawing from phenomenological interviews with 24 adult videogamers, we explore videogame consumption as a source of individualised, episodic progress. We first consider the relationship between play, progress, technology and the market. We then document adults' accounts of progress through the acquisition of new consoles and software, in the accumulation of in-game resources, and in creative achievements within videogames. Alongside an understanding of technological improvements as representing both technological and personal progress, we see how individuals may also turn to videogames in search of quick and easy episodes of achievement; here, progress is not some grand plan, but a series of small events helpfully structured by the latest game releases. Thus, in a society which aspires to a life where things ‘get better’ and time is usefully spent, adults who fail to actualise progress elsewhere may use videogames and related hardware to perform the idea of achievement as individualised episodes of play. In integrating the accepted cultural idea of progress, perceptions of adult play as ‘frivolous’ can be overcome and such practices may be normalised as a legitimate adult activity. However, play emerges from its frivolousness as legitimate only in compensating for working practices that remain alienated through technology-driven productivity, and through the latest technological commodities. The enjoyable nature of games as a leisure pursuit can become overshadowed by an obligation to achieve at the same time as distancing players from areas of their lives where progress is not experienced

Condensation in nongeneric trees

We study nongeneric planar trees and prove the existence of a Gibbs measure on infinite trees obtained as a weak limit of the finite volume measures. It is shown that in the infinite volume limit there arises exactly one vertex of infinite degree and the rest of the tree is distributed like a subcritical Galton-Watson tree with mean offspring probability $m<1$. We calculate the rate of divergence of the degree of the highest order vertex of finite trees in the thermodynamic limit and show it goes like $(1-m)N$ where $N$ is the size of the tree. These trees have infinite spectral dimension with probability one but the spectral dimension calculated from the ensemble average of the generating function for return probabilities is given by $2\beta -2$ if the weight $w_n$ of a vertex of degree $n$ is asymptotic to $n^{-\beta}$.Comment: 57 pages, 14 figures. Minor change

Compensation for research-related injury in South Africa: A critique of the good clinical practice (GCP) guidelines

This article examines the current South African Department of Health Good Clinical Practice (2006) guideline recommendations regarding compensation for harm incurred in clinical trials. It applies the case of a phase IIb HIV vaccine trial in South Africa, for which enrolments and vaccinations were suspended early, based on data from an international companion study that indicated no evidence of efficacy and greater susceptibility to HIV infection in a subgroup of vaccinees. The case application indicates certain substantive and procedural limitations within the South African Department of Health Good Clinical Practice (2006) guideline recommendations on compensation for harm, which should be re-considered in order to improve protections for trial participants

HIV prevention responsibilities in HIV vaccine trials: Complexities facing South African researchers

Researchers should protect the welfare of research participants through providing methods to reduce their risk of acquiring HIV. This is especially important given that latephase HIV vaccine trials enrol HIV-uninfected trial volunteers from high-risk populations.Current ethical guidelines may be difficult for stakeholders toimplement, and we know very little about what prevention services researchers are currently providing to participants or their successes, best practices and challenges. We recommend that current normative guidance be systematically reviewed and actual practice at vaccine sites be documented. Adding new tools to the current package of prevention services will involve complex decision making with fewset standards, and regulatory and scientific challenges. Werecommend that stakeholders (including regulators) convene to consider standards of evidence for new tools, and that decision-making processes be explicitly documented and researched. A further critical ethical task is exploring the threshold at which adding new tools will compromise thevalidity of trial results

The convective storm initiation project

Copyright @ 2007 AMSThe Convective Storm Initiation Project (CSIP) is an international project to understand precisely where, when, and how convective clouds form and develop into showers in the mainly maritime environment of southern England. A major aim of CSIP is to compare the results of the very high resolution Met Office weather forecasting model with detailed observations of the early stages of convective clouds and to use the newly gained understanding to improve the predictions of the model. A large array of ground-based instruments plus two instrumented aircraft, from the U.K. National Centre for Atmospheric Science (NCAS) and the German Institute for Meteorology and Climate Research (IMK), Karlsruhe, were deployed in southern England, over an area centered on the meteorological radars at Chilbolton, during the summers of 2004 and 2005. In addition to a variety of ground-based remote-sensing instruments, numerous rawin-sondes were released at one- to two-hourly intervals from six closely spaced sites. The Met Office weather radar network and Meteosat satellite imagery were used to provide context for the observations made by the instruments deployed during CSIP. This article presents an overview of the CSIP field campaign and examples from CSIP of the types of convective initiation phenomena that are typical in the United Kingdom. It shows the way in which certain kinds of observational data are able to reveal these phenomena and gives an explanation of how the analyses of data from the field campaign will be used in the development of an improved very high resolution NWP model for operational use.This work is funded by the National Environment Research Council following an initial award from the HEFCE Joint Infrastructure Fund

Thermoelectric properties of lead chalcogenide core-shell nanostructures

We present the full thermoelectric characterization of nanostructured bulk PbTe and PbTe-PbSe samples fabricated from colloidal core-shell nanoparticles followed by spark plasma sintering. An unusually large thermopower is found in both materials, and the possibility of energy filtering as opposed to grain boundary scattering as an explanation is discussed. A decreased Debye temperature and an increased molar specific heat are in accordance with recent predictions for nanostructured materials. On the basis of these results we propose suitable core-shell material combinations for future thermoelectric materials of large electric conductivities in combination with an increased thermopower by energy filtering.Comment: 12 pages, 8 figure