Application of the discrete Wentzel-Kramers-Brillouin method to spin tunneling

A discrete version of the WKB method is developed and applied to calculate the tunnel splittings between classically degenerate states of spin Hamiltonians. The results for particular model problems are in complete accord with those previously found using instanton methods. The discrete WKB method is more elementary and also yields wavefunctions.Comment: RevTex, 2ps figures, incorporates errata (typos and omitted reference) in JMP pape

The conduct and reporting of mediation analysis in recently published randomized controlled trials : results from a methodological systematic review

Objectives: To describe the methodological characteristics of mediation analyses (MAs) reported in recent randomized controlled trials (RCTs) and to propose recommendations on the planning, conduct, and reporting of MAs in practice. Study Design and Setting: We conducted a systematic review by searching MEDLINE (January 1, 2017, to December 1, 2018) for all reports of RCTs or secondary analyses of previously published RCTs that reported a MA. Two reviewers independently screened the title, abstracts, and full texts of the identified reports and extracted the data from the 98 eligible studies. Results: MAs were nearly always (96%) based on a traditional mediation approach. Most studies did not report a sample size calculation for the MA (96%) or assess potential treatment-by-mediator interactions (96%). In 53% of studies, mediators and outcomes were simultaneously measured. In 57% of studies, mediator-mediator and mediator-outcome confounders were adjusted for in the analysis, although adjustment was often limited to few potential confounders. About 30% of studies discussed the assumptions underlying the MA. Conclusion: The conduct and reporting of MAs remained quite heterogeneous in practice. Future MAs could benefit from a consensus-based planning, conduct, and reporting guideline for MA

Para no pasar del fusil a la olla: retos de la reincorporación civil y política de las mujeres guerrilleras en Colombia

Existen muchas barreras especiales a la reincorporación civil y política de las mujeres guerrilleras en Colombia, pero la importancia del “feminismo insurgente” dentro del proceso de paz trae nuevas ideas y nuevas esperanzas para el futuro, escriben Camille Boutron y Diana Gómez

From rifles to aprons? The challenges of reincorporating Colombia’s female ex-combatants into civilian and political life

Though female members of the Farc guerrilla movement face special barriers in their reintegration into wider society, the prominence of “insurgent feminism” within the peace process provides hope for the future, write Camille Boutron and Diana Gómez

Scoping review on interventions to improve adherence to reporting guidelines in health research

Objectives The goal of this study is to identify, analyse and classify interventions to improve adherence to reporting guidelines in order to obtain a wide picture of how the problem of enhancing the completeness of reporting of biomedical literature has been tackled so far. Design Scoping review. Search strategy We searched the MEDLINE, EMBASE and Cochrane Library databases and conducted a grey literature search for (1) studies evaluating interventions to improve adherence to reporting guidelines in health research and (2) other types of references describing interventions that have been performed or suggested but never evaluated. The characteristics and effect of the evaluated interventions were analysed. Moreover, we explored the rationale of the interventions identified and determined the existing gaps in research on the evaluation of interventions to improve adherence to reporting guidelines. Results 109 references containing 31 interventions (11 evaluated) were included. These were grouped into five categories: (1) training on the use of reporting guidelines, (2) improving understanding, (3) encouraging adherence, (4) checking adherence and providing feedback, and (5) involvement of experts. Additionally, we identified lack of evaluated interventions (1) on training on the use of reporting guidelines and improving their understanding, (2) at early stages of research and (3) after the final acceptance of the manuscript. Conclusions This scoping review identified a wide range of strategies to improve adherence to reporting guidelines that can be taken by different stakeholders. Additional research is needed to assess the effectiveness of many of these interventionsPeer ReviewedPostprint (author's final draft

Tunneling Rate for Superparamagnetic Particles by the Instanton Method

We derive the tunneling rate for paramagnetic molecules in the context of a collective spin model. By means of path integral methods an analytical expression is derived. Given the very large spins in question (s ~ 3000 hbar), the observation of magnetization changes due to pure unitary tunnel effects is unlikely.Comment: 16 pages, 2 figure

Relative levels of natural and anthropogenic lead in recent Antarctic snow

Concentrations of lead have been measured by ultraclean isotope dilution mass spectrometry in large blocks of surface snow collected along a 433-km coast-interior axis in East Antarctica and near the geographic south pole. Slight contamination existed on the outside of the blocks, but concentration profiles from their exteriors to their interiors indicate that lead concentrations in the innermost parts of the blocks do represent the original concentrations in present-day Antarctic snow. Geographical variations of lead concentrations appear to be mainly due to local emissions from Dumont d'Urville and Amundsen Scott stations. The globally significant lead concentration in present-day Antarctic snow is found to be about 2 pg Pb/g. The corresponding value in Antarctic air is estimated to be about 7 pg Pb/m^3 STP, which is approximately fivefold larger than total natural lead contributed by soil dusts, volcanoes and sea salts. A tentative temporal curve of globally significant lead concentrations in Antarctic ice and snow for the last 13,000 years is given. It shows concentrations of about 0.4 pg Pb/g throughout most of the Holocene, with recent fivefold increases to about 2 pg Pb/g today. The general picture is then that four-fifths of total lead in the Antarctic troposphere today is anthropogenic

Detection of Trace Amounts of Toxic Metals in Environmental Samples by Laser-excited Atomic Fluorescence Spectrometry

Results for the direct determination of trace amounts of Pb and Cd in Antarctic and Greenland ancient ice and recent snow by laser-excited atomic fluorescence spectrometry (LEAFS) are presented. The whole procedure starting from field sampling, mechanical decontamination of the samples in an ultra-clean laboratory and final analysis of the decontaminated samples is described. The measured concentrations varied in the ranges 0.1–3 pg ml^(–1) for Cd and 0.3–30 pg ml^(–1) for Pb. The results for direct analysis by LEAFS agree favourable with those obtained by isotope dilution mass spectrometry and electrothermal atomic absorption spectrometry, which require time-consuming pre-treatment and pre-concentration stages

Activities to support the implementation of complex interventions as part of routine care: a review of the quality of reporting in cluster randomised controlled trials

Objective: To review a sample of cluster randomised controlled trials and explore the quality of reporting of (1) enabling or support activities provided to the staff during the trial, (2) strategies used to monitor fidelity throughout the trial and (3) the extent to which the intervention being tested was delivered as planned. Design: A descriptive review. Data sources and study selection: We searched MEDLINE for trial reports published between 2008 and 2014 with combinations of the search terms 'randomised', 'cluster', 'trial', 'study', 'intervention' and 'implement∗'. We included trials in which healthcare professionals (HCPs) implemented the intervention being tested as part of routine practice. We excluded trials (1) conducted in non-health services settings, (2) where the intervention explicitly aimed to change the behaviours of the HCPs and (3) where the trials were ongoing or for which only trial protocols were available. Data collection: We developed a data extraction form using the Template for Intervention Description and Replication (TIDieR checklist). Review authors independently extracted data from the included trials and assessed quality of reporting for individual items. Results: We included 70 publications (45 results publications, 25 related publications). 89% of trials reported using enabling or support activities. How these activities were provided (75.6%, n=34) and how much was provided (73.3%, n=33) were the most frequently reported items. Less than 20% (n=8) of the included trials reported that competency checking occurred prior to implementation and data collection. 64% (n=29) of trials reported collecting measures of implementation. 44% (n=20) of trials reported data from these measures. Conclusions: Although enabling and support activities are reported in trials, important gaps exist when assessed using an established checklist. Better reporting of the supports provided in effectiveness trials will allow for informed decisions to be made about financial and resource implications for wide scale implementation of effective interventions

Factors Associated with Results and Conclusions of Trials of Thiazolidinediones

When a sponsor funds a study of two competing drugs in a head-to-head comparison, the results and conclusions are likely to favor the sponsor's drug. Thiazolidinediones, oral medications used for the treatment of type 2 diabetes, are one of the most costly choices of oral anti-diabetic medications, yet they do not demonstrate clinically relevant differences in achieving lower glycosylated hemoglobin levels compared to other oral antidiabetic drugs. Our aim is to examine associations between research funding source, study design characteristics aimed at reducing bias, and other factors with the results and conclusions of randomized controlled trials (RCTs) of thiazolidinediones compared to other oral hypoglycemic agents.This is a cross-sectional study of 61 published RCTs comparing a thiazolidinedione (glitazone) to another anti-diabetic drug or placebo for treatment of type 2 diabetes. Data on study design characteristics, funding source, author's financial ties, results for primary outcomes, and author conclusions were extracted. Univariate logistic regression identified associations between independent variables and results and conclusions that favored the glitazone. Of the RCTs, 59% (36/61) were funded by industry, 39% (24/61) did not disclose any funding. Common study design weaknesses included inadequate blinding and lack of concealment of allocation. Trials that reported favorable glycemic control results for the glitazone were more likely to have adequate blinding (OR (95% CI) = 5.42 (1.46, 21.19), p = 0.008) and have a corresponding author with financial ties to the glitazone manufacturer (OR (95% CI) = 4.12 (1.05, 19.53); p = 0.04). Trials with conclusions favoring the glitazone were less likely to be funded by a comparator drug company than a glitazone company (OR (95% CI) = 0.026 (0, 0.40), p = 0.003) and less likely to be published in journals with higher impact factors (OR (95% CI) = 0.79 (0.62, 0.97), p = 0.011). One limitation of our study is that we categorized studies as funded by industry based on each article's disclosure which could underestimate the number of industry sponsored studies and personal ties of investigators. Additionally, our study did not include any head-to-head comparisons of one glitazone to another.Published RCT comparisons of glitazones with other anti-diabetic drugs or placebo are predominantly industry supported and this support, as well as the financial ties of study authors, appears to be associated with favorable findings