Inter-laboratory comparison of elemental analysis and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS). Part I: delta13C measurements of selected compounds for the development of an isotopic Grob-test.

This study was directed towards investigating suitable compounds to be used as stable isotope reference materials for gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) calibration. Several compounds were selected from those used in the 'Grob-test' mixture. Oxygen- and nitrogen-containing substances were added to these compounds to allow the mixture to be used as a possible multi-isotopic calibration tool for 2H/1H, 13C/12C, 15N/14N and 18O/16O ratio determinations. In this paper we present the results of delta13C measurements performed by the consortium of the five laboratories taking part in this inter-calibration exercise. All the compounds were individually assessed for homogeneity, short-term stability and long-term stability by means of EA-IRMS, as required by the bureau communitaire de reference (BCR) Guide for Production of Certified Reference Materials. The results were compared then with the GC-C-IRMS measurements using both polar and non-polar columns, and the final mixture of selected compounds underwent a further certification exercise assessing limits of accuracy and reproducibility under specified GC-C-IRMS conditions.

Prevention and health policy: a view from the social sciences.

A theoretical framework is outlined which identifies four major problem areas which must be dealt with in the formulation, implementation, and evaluation of social policy. Certain issues relevant to policy concerning health promotion and disease prevention are discussed within this framework. The first problem area, adaptation, is concerned primarily with resources; the second area, goal attainment, deals with organizational issues; the third, integration, is concerned with motivations; the fourth, pattern maintenance, concentrates on questions of values. Policymaking is seen as an attempt by governing bodies to resolve problems in all these areas, and the success of any policy may be judged by the extent to which major issues in each area are dealt with equitably and reasonably.

GRB 130427A: a nearby ordinary monster.

Long-duration gamma-ray bursts (GRBs) are an extremely rare outcome of the collapse of massive stars and are typically found in the distant universe. Because of its intrinsic luminosity (L ~ 3 × 10(53) ergs per second) and its relative proximity (z = 0.34), GRB 130427A reached the highest fluence observed in the γ-ray band. Here, we present a comprehensive multiwavelength view of GRB 130427A with Swift, the 2-meter Liverpool and Faulkes telescopes, and by other ground-based facilities, highlighting the evolution of the burst emission from the prompt to the afterglow phase. The properties of GRB 130427A are similar to those of the most luminous, high-redshift GRBs, suggesting that a common central engine is responsible for producing GRBs in both the contemporary and the early universe and over the full range of GRB isotropic energies.

Public health consequences of different thresholds for the diagnosis of mental disorders.

The acceptance of subthreshold disorders in psychiatry is a controversial topic with multiple implications for public health policy. Using subthreshold depression as an example, we provide documentation based on data from epidemiologic and clinical studies suggesting that subthreshold conditions are not uncommon, there is significant associated disability (with significant societal costs), and the course of illness often leads to the development of the full-blown disorder. The potential societal benefits of developing and testing low-cost, low-risk, and nontraditional treatments are considered. The recommendations are to match treatment intensity and cost with severity level in a staged approach.