Contrasting charge-carrier dynamics across key metal-halide perovskite compositions through in situ simultaneous probes

Metal-halide perovskites have proven to be a versatile group of semiconductors for optoelectronic applications, with ease of bandgap tuning and stability improvements enabled by halide and cation mixing. However, such compositional variations can be accompanied by significant changes in their charge-carrier transport and recombination regimes that are still not fully understood. Here, a novel combinatorial technique is presented to disentangle such dynamic processes over a wide range of temperatures, based on transient free-space, high-frequency microwave conductivity and photoluminescence measurements conducted simultaneously in situ. Such measurements are used to reveal and contrast the dominant charge-carrier recombination pathways for a range of key compositions: prototypical methylammonium lead iodide perovskite (MAPbI3), the stable mixed formamidinium-caesium lead-halide perovskite FA0.83Cs0.17PbBr0.6I2.4 targeted for photovoltaic tandems with silicon, and fully inorganic wide-bandgap CsPbBr3 aimed toward light sources and X-ray detector applications. The changes in charge-carrier dynamics in FA0.83Cs0.17PbBr0.6I2.4 across temperatures are shown to be dominated by radiative processes, while those in MAPbI3 are governed by energetic disorder at low temperatures, low-bandgap minority-phase inclusions around the phase transition, and non-radiative processes at room temperature. In contrast, CsPbBr3 exhibits significant charge-carrier trapping at low and high temperatures, highlighting the need for improvement of material processing techniques for wide-bandgap perovskites

Better data for teachers, better data for learners, better patient care: college-wide assessment at Michigan State University's College of Human Medicine

When our school organized the curriculum around a core set of medical student competencies in 2004, it was clear that more numerous and more varied student assessments were needed. To oversee a systematic approach to the assessment of medical student competencies, the Office of College-wide Assessment was established, led by the Associate Dean of College-wide Assessment. The mission of the Office is to ‘facilitate the development of a seamless assessment system that drives a nimble, competency-based curriculum across the spectrum of our educational enterprise.’ The Associate Dean coordinates educational initiatives, developing partnerships to solve common problems, and enhancing synergy within the College. The Office also works to establish data collection and feedback loops to guide rational intervention and continuous curricular improvement. Aside from feedback, implementing a systems approach to assessment provides a means for identifying performance gaps, promotes continuity from undergraduate medical education to practice, and offers a rationale for some assessments to be located outside of courses and clerkships. Assessment system design, data analysis, and feedback require leadership, a cooperative faculty team with medical education expertise, and institutional support. The guiding principle is ‘Better Data for Teachers, Better Data for Learners, Better Patient Care.’ Better data empowers faculty to become change agents, learners to create evidence-based improvement plans and increases accountability to our most important stakeholders, our patients

Obesity as Assessed by Body Adiposity Index and Multivariable Cardiovascular Disease Risk

To assess the role of body adiposity index (BAI) in predicting cardiovascular disease (CVD) and coronary heart disease (CHD) mortality, in comparison with body mass index (BMI), waist circumference (WC), and the waist circumference to hip circumference ratio (WHR). This study was a prospective 15 year mortality follow-up of 4175 Australian males, free of heart disease, diabetes and stroke. The Framingham Risk Scores (FRS) for CHD and CVD death were calculated at baseline for all subjects. Multivariable logistic regression was used to assess the effects of the measures of obesity on CVD and CHD mortality, before adjustment and after adjustment for FRS. The predictive ability of BAI, though present in the unadjusted analyses, was generally not significant after adjustment for age and FRS for both CVD and CHD mortality. BMI behaved similarly to BAI in that its predictive ability was generally not significant after adjustments. Both WC and WHR were significant predictors of CVD and CHD mortality and remained significant after adjustment for covariates. BAI appeared to be of potential interest as a measure of % body fat and of obesity, but was ineffective in predicting CVD and CHD

Understanding the implementation of evidence-based care: A structural network approach

<p>Abstract</p> <p>Background</p> <p>Recent study of complex networks has yielded many new insights into phenomenon such as social networks, the internet, and sexually transmitted infections. The purpose of this analysis is to examine the properties of a network created by the 'co-care' of patients within one region of the Veterans Health Affairs.</p> <p>Methods</p> <p>Data were obtained for all outpatient visits from 1 October 2006 to 30 September 2008 within one large Veterans Integrated Service Network. Types of physician within each clinic were nodes connected by shared patients, with a weighted link representing the number of shared patients between each connected pair. Network metrics calculated included edge weights, node degree, node strength, node coreness, and node betweenness. Log-log plots were used to examine the distribution of these metrics. Sizes of k-core networks were also computed under multiple conditions of node removal.</p> <p>Results</p> <p>There were 4,310,465 encounters by 266,710 shared patients between 722 provider types (nodes) across 41 stations or clinics resulting in 34,390 edges. The number of other nodes to which primary care provider nodes have a connection (172.7) is 42% greater than that of general surgeons and two and one-half times as high as cardiology. The log-log plot of the edge weight distribution appears to be linear in nature, revealing a 'scale-free' characteristic of the network, while the distributions of node degree and node strength are less so. The analysis of the k-core network sizes under increasing removal of primary care nodes shows that about 10 most connected primary care nodes play a critical role in keeping the <it>k</it>-core networks connected, because their removal disintegrates the highest <it>k</it>-core network.</p> <p>Conclusions</p> <p>Delivery of healthcare in a large healthcare system such as that of the US Department of Veterans Affairs (VA) can be represented as a complex network. This network consists of highly connected provider nodes that serve as 'hubs' within the network, and demonstrates some 'scale-free' properties. By using currently available tools to explore its topology, we can explore how the underlying connectivity of such a system affects the behavior of providers, and perhaps leverage that understanding to improve quality and outcomes of care.</p

Specific Responses of Salmonella enterica to Tomato Varieties and Fruit Ripeness Identified by In Vivo Expression Technology

Recent outbreaks of vegetable-associated gastroenteritis suggest that enteric pathogens colonize, multiply and persist in plants for extended periods of time, eventually infecting people. Genetic and physiological pathways, by which enterics colonize plants, are still poorly understood.To better understand interactions between Salmonella enterica sv. Typhimurium and tomatoes, a gfp-tagged Salmonella promoter library was screened inside red ripe fruits. Fifty-one unique constructs that were potentially differentially regulated in tomato relative to in vitro growth were identified. The expression of a subset of these promoters was tested in planta using recombinase-based in vivo expression technology (RIVET) and fitness of the corresponding mutants was tested. Gene expression in Salmonella was affected by fruit maturity and tomato cultivar. A putative fadH promoter was upregulated most strongly in immature tomatoes. Expression of the fadH construct depended on the presence of linoleic acid, which is consistent with the reduced accumulation of this compound in mature tomato fruits. The cysB construct was activated in the fruit of cv. Hawaii 7997 (resistant to a race of Ralstonia solanacearum) more strongly than in the universally susceptible tomato cv. Bonny Best. Known Salmonella motility and animal virulence genes (hilA, flhDC, fliF and those encoded on the pSLT virulence plasmid) did not contribute significantly to fitness of the bacteria inside tomatoes, even though deletions of sirA and motA modestly increased fitness of Salmonella inside tomatoes.This study reveals the genetic basis of the interactions of Salmonella with plant hosts. Salmonella relies on a distinct set of metabolic and regulatory genes, which are differentially regulated in planta in response to host genotype and fruit maturity. This enteric pathogen colonizes tissues of tomatoes differently than plant pathogens, and relies little on its animal virulence genes for persistence within the fruit

A Risk Score to Predict Type 2 Diabetes Mellitus in an Elderly Spanish Mediterranean Population at High Cardiovascular Risk

Abstract Introduction: To develop and test a diabetes risk score to predict incident diabetes in an elderly Spanish Mediterranean population at high cardiovascular risk. Materials and Methods: A diabetes risk score was derived from a subset of 1381 nondiabetic individuals from three centres of the PREDIMED study (derivation sample). Multivariate Cox regression model ß-coefficients were used to weigh each risk factor. PREDIMED-personal Score included body-mass-index, smoking status, family history of type 2 diabetes, alcohol consumption and hypertension as categorical variables; PREDIMED-clinical Score included also high blood glucose. We tested the predictive capability of these scores in the DE-PLAN-CAT cohort (validation sample). The discrimination of Finnish Diabetes Risk Score (FINDRISC), German Diabetes Risk Score (GDRS) and our scores was assessed with the area under curve (AUC). Results: The PREDIMED-clinical Score varied from 0 to 14 points. In the subset of the PREDIMED study, 155 individuals developed diabetes during the 4.75-years follow-up. The PREDIMED-clinical score at a cutoff of $6 had sensitivity of 72.2%, and specificity of 72.5%, whereas AUC was 0.78. The AUC of the PREDIMED-clinical Score was 0.66 in the validation sample (sensitivity = 85.4%; specificity = 26.6%), and was significantly higher than the FINDRISC and the GDRS in both the derivation and validation samples. Discussion: We identified classical risk factors for diabetes and developed the PREDIMED-clinical Score to determine those individuals at high risk of developing diabetes in elderly individuals at high cardiovascular risk. The predictive capability of the PREDIMED-clinical Score was significantly higher than the FINDRISC and GDRS, and also used fewer items in the questionnaire

Dairy products and total calcium intake at 13 years of age and its association with obesity at 21 years of age

Background/objectives: Dairy products and specifically calcium have been suggested to play a role in obesity development but more longitudinal evidence is still needed. The objective of this study was to assess the association between dairy products and total calcium intake at age 13 and body mass index at age 21. Subjects/methods: This longitudinal study included 2159 individuals from the Epidemiological Health Investigation of Teenagers cohort (EPITeen), Porto, Portugal, evaluated at ages 13 and 21. Assessment consisted of anthropometrics measurements and structured questionnaires namely a semi-quantitative food frequency questionnaire to appraise food consumption in the past 12 months. Linear regression models were run in 941 individuals with complete information of confounders: gender, follow-up period, parents’ education, physical activity, energy, and total calcium intake. Results: Negative association was found on total calcium intake at age 13 with BMI at age 21 (model 0: β = −0.059 (95% CI: −0.113, −0.004) and model 1: −0.057 (95% CI: −0.113, −0.002)), however, no statistically significant association was found when adjusting for energy intake (model 2: β = −0.031 (95% CI: −0.110, 0.047). There were no associations between milk, yogurt, and cheese consumption at age 13 and BMI at age 21 when adjusting for confounders. Conclusions: This study did not support an independent effect of dairy products or total calcium intake in adolescence on later early adulthood adiposity.This study was funded by FEDER through the Operational Programme Competitiveness and Internationalization and national funding from the Foundation for Science and Technology—FCT (Portuguese Ministry of Science, Technology and Higher Education) (POCI-01-0145-FEDER-016829), under the project MetHyOS (Ref. FCT PTDC/DTP-EPI/6506/2014) and the Unidade de Investigação em Epidemiologia—Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862; Ref. UID/DTP/04750/2013). Also this study was developed with the support of the research teams of the Department of Public Health and Forensic Sciences, and Medical Education, Faculty of Medicine of Porto University; the EPIUnit—Public Health Institute of Porto University; and the EPITeen Cohort Study

Emergence of terpene cyclization in Artemisia annua

The emergence of terpene cyclization was critical to the evolutionary expansion of chemical diversity yet remains unexplored. Here we report the first discovery of an epistatic network of residues that controls the onset of terpene cyclization in Artemisia annua. We begin with amorpha-4,11-diene synthase (ADS) and (E)-b-farnesene synthase (BFS), a pair of terpene synthases that produce cyclic or linear terpenes, respectively. A library of B27,000 enzymes is generated by breeding combinations of natural amino-acid substitutions from the cyclic into the linear producer. We discover one dominant mutation is sufficient to activate cyclization, and together with two additional residues comprise a network of strongly epistatic interactions that activate, suppress or reactivate cyclization. Remarkably, this epistatic network of equivalent residues also controls cyclization in a BFS homologue from Citrus junos. Fitness landscape analysis of mutational trajectories provides quantitative insights into a major epoch in specialized metabolism

Menopausal Status Modifies Breast Cancer Risk Associated with the Myeloperoxidase (MPO) G463A Polymorphism in Caucasian Women: A Meta-Analysis

BACKGROUND: Breast cancer susceptibility may be modulated partly through polymorphisms in oxidative enzymes, one of which is myeloperoxidase (MPO). Association of the low transcription activity variant allele A in the G463A polymorphism has been investigated for its association with breast cancer risk, considering the modifying effects of menopausal status and antioxidant intake levels of cases and controls. METHODOLOGY/PRINCIPAL FINDINGS: To obtain a more precise estimate of association using the odds ratio (OR), we performed a meta-analysis of 2,975 cases and 3,427 controls from three published articles of Caucasian populations living in the United States. Heterogeneity among studies was tested and sensitivity analysis was applied. The lower transcriptional activity AA genotype of MPO in the pre-menopausal population showed significantly reduced risk (OR 0.56-0.57, p = 0.03) in contrast to their post-menopausal counterparts which showed non-significant increased risk (OR 1.14; p = 0.34-0.36). High intake of antioxidants (OR 0.67-0.86, p = 0.04-0.05) and carotenoids (OR 0.68-0.86, p = 0.03-0.05) conferred significant protection in the women. Stratified by menopausal status, this effect was observed in pre-menopausal women especially those whose antioxidant intake was high (OR 0.42-0.69, p = 0.04). In post-menopausal women, effect of low intake elicited susceptibility (OR 1.19-1.67, p = 0.07-0.17) to breast cancer. CONCLUSIONS/SIGNIFICANCE: Based on a homogeneous Caucasian population, the MPO G463A polymorphism places post-menopausal women at risk for breast cancer, where this effect is modified by diet