College students’ motivational beliefs and use of goal-oriented control strategies : Integrating two theories of motivated behavior

In college, students often encounter situations in which they struggle to meet their academic goals in difficult courses. We integrate the Motivational Theory of Life-Span Development and Situated Expectancy-Value Theory to investigate how motivational beliefs and experiences in a difficult course predict the use of goal engagement oriented and goal adjustment oriented control strategies that can help students stay engaged in challenging courses. We used survey data collected in two academic quarters at a public university in the U.S. (N = 231). Students who perceived their midterm exam as more difficult than expected and students with higher course-specific subjective task values reported using more goal engagement oriented and goal adjustment oriented control strategies. Students with higher course-specific ability beliefs were less likely to use goal adjustment strategies. Results further showed that students planned to use control strategies depending on their experienced setbacks or success in exams. Findings provide important insights into how motivational orientations and course experiences relate to adaptive and goal-oriented behavior in college courses

Competence acquisition for single-incision laparoscopic cholecystectomy

BACKGROUND AND OBJECTIVES: Within the past few years, there has been a push for an even more minimally invasive approach to biliary disease with the adoption of single-incision laparoscopic cholecystectomy. We sought to compare 4 individual surgeon experiences to define whether there exists a learning curve for performing single-incision laparoscopic cholecystectomy. METHODS: We performed a retrospective review 290 single-incision laparoscopic cholecystectomies performed by a group of general surgeons, with varying levels of experience and training, at 3 institutions between May 2008 and September 2010. The procedure times were recorded for each single-incision laparoscopic cholecystectomy, ordered chronologically for each surgeon, and subsequently plotted on a graph. The patients were also combined into cohorts of 5 and 10 cases to further evaluate for signs of improvement in operative efficiency. RESULTS: Of the 4 surgeons involved in the study, only 1 (surgeon 4, laparoscopic fellowship trained with \u3c5 \u3eyears\u27 experience) confirmed the presence of a learning curve, reaching proficiency within the first 15 cases performed. The other surgeons had more variable procedure times, which did not show a distinct trend. When we evaluated the cases by cohorts of 5 cases, surgeon 4 had a significant difference between the first and last cohort. Increased body mass index resulted in a slightly longer operative time (P \u3c .0063). The conversion rate to multiport laparoscopic surgery was 3.1%. CONCLUSIONS: Our results indicate that among experienced general surgeons, there does not seem to be a significant learning curve when transitioning from conventional laparoscopic cholecystectomy to single-incision laparoscopic cholecystectomy. The least experienced surgeon in the group, surgeon 4, appeared to reach proficiency after 15 cases. Greater than 5 years of experience in laparoscopic surgery appears to provide surgeons with a sufficient skill set to obviate the need for a single-incision laparoscopic cholecystectomy learning curve

Epidemiology of Coxiella burnetii infection in Africa: a OneHealth systematic review

Background: Q fever is a common cause of febrile illness and community-acquired pneumonia in resource-limited settings. Coxiella burnetii, the causative pathogen, is transmitted among varied host species, but the epidemiology of the organism in Africa is poorly understood. We conducted a systematic review of C. burnetii epidemiology in Africa from a “One Health” perspective to synthesize the published data and identify knowledge gaps.<p></p> Methods/Principal Findings: We searched nine databases to identify articles relevant to four key aspects of C. burnetii epidemiology in human and animal populations in Africa: infection prevalence; disease incidence; transmission risk factors; and infection control efforts. We identified 929 unique articles, 100 of which remained after full-text review. Of these, 41 articles describing 51 studies qualified for data extraction. Animal seroprevalence studies revealed infection by C. burnetii (≤13%) among cattle except for studies in Western and Middle Africa (18–55%). Small ruminant seroprevalence ranged from 11–33%. Human seroprevalence was <8% with the exception of studies among children and in Egypt (10–32%). Close contact with camels and rural residence were associated with increased seropositivity among humans. C. burnetii infection has been associated with livestock abortion. In human cohort studies, Q fever accounted for 2–9% of febrile illness hospitalizations and 1–3% of infective endocarditis cases. We found no studies of disease incidence estimates or disease control efforts.<p></p> Conclusions/Significance: C. burnetii infection is detected in humans and in a wide range of animal species across Africa, but seroprevalence varies widely by species and location. Risk factors underlying this variability are poorly understood as is the role of C. burnetii in livestock abortion. Q fever consistently accounts for a notable proportion of undifferentiated human febrile illness and infective endocarditis in cohort studies, but incidence estimates are lacking. C. burnetii presents a real yet underappreciated threat to human and animal health throughout Africa.<p></p&gt

A toxicokinetic model for thiamethoxam in rats: implications for higher-tier risk assessment

Risk assessment for mammals is currently based on external exposure measurements, but effects of toxicants are better correlated with the systemically available dose than with the external administered dose. So for risk assessment of pesticides, toxicokinetics should be interpreted in the context of potential exposure in the field taking account of the timescale of exposure and individual patterns of feeding. Internal concentration is the net result of absorption, distribution, metabolism and excretion (ADME). We present a case study for thiamethoxam to show how data from ADME study on rats can be used to parameterize a body burden model which predicts body residue levels after exposures to LD50 dose either as a bolus or eaten at different feeding rates. Kinetic parameters were determined in male and female rats after an intravenous and oral administration of 14C labelled by fitting one-compartment models to measured pesticide concentrations in blood for each individual separately. The concentration of thiamethoxam in blood over time correlated closely with concentrations in other tissues and so was considered representative of pesticide concentration in the whole body. Body burden model simulations showed that maximum body weight-normalized doses of thiamethoxam were lower if the same external dose was ingested normally than if it was force fed in a single bolus dose. This indicates lower risk to rats through dietary exposure than would be estimated from the bolus LD50. The importance of key questions that should be answered before using the body burden approach in risk assessment, data requirements and assumptions made in this study are discussed in detail

The isotope effect of nitrate assimilation in the Antarctic Zone: Improved estimates and paleoceanographic implications

Both the nitrogen (N) isotopic composition (δ^(15)N) of the nitrate source and the magnitude of isotope discrimination associated with nitrate assimilation are required to estimate the degree of past nitrate consumption from the δ^(15)N of organic matter in Southern Ocean sediments (e.g., preserved within diatom microfossils). It has been suggested that the amplitude of isotope discrimination (i.e. the isotope effect) correlates with mixed layer depth, driven by a physiological response of phytoplankton to light availability, which introduces complexity to the interpretation of sedimentary records. However, most of the isotope effectestimates that underpin this hypothesis derive from acid-preserved water samples, from which nitrite would have been volatilized and lost during storage. Nitrite δ^(15)N in Antarctic Zone surface waters is extremely low (−61 ± 20‰), consistent with the expression of an equilibrium isotope effect associated with nitrate–nitrite interconversion. Its loss from the combined nitrate + nitrite pool would act to raise the δ^(15)N of nitrate, potentially yielding overestimation of the isotope effect. Here, we revisit the nitrate assimilation isotope effect in the Antarctic Zone with measurements of the δ^(15)N and concentration of nitrate with and without nitrite, using frozen sea water samples from 5 different cruises that collectively cover all sectors of the Southern Ocean. The N isotope effect estimated using nitrate + nitrite δ^(15)N is relatively constant (5.5 ± 0.6‰) across the Antarctic Zone, shows no relationship with mixed layer depth, and is in agreement with sediment trap δ^(15)N measurements. Estimates of the N isotope effect derived from nitrate-only δ^(15)N are higher and more variable (7.9 ± 1.5‰), consistent with an artifact from nitrate-nitrite isotope exchange. In the case of the Southern Ocean, we conclude that the δ^(15)N of nitrate + nitrite better reflects the isotope effect of nitrate assimilation. The stability of this isotope effect across the Antarctic Zone simplifies the effort to reconstruct the past degree of nitrate consumption

Is hepatitis C virus elimination possible among people living with HIV and what will it take to achieve it?

Introduction The World Health Organization targets for hepatitis C virus (HCV) elimination include a 90% reduction in new infections by 2030. Our objective is to review the modelling evidence and cost data surrounding feasibility of HCV elimination among people living with HIV (PLWH), and identify likely components for elimination. We also discuss the real‐world experience of HCV direct acting antiviral (DAA) scale‐up and elimination efforts in the Netherlands. Methods We review modelling evidence of what intervention scale‐up is required to achieve WHO HCV elimination targets among HIV‐infected (HIV+) people who inject drugs (PWID) and men who have sex with men (MSM), review cost‐effectiveness of HCV therapy among PLWH and discuss economic implications of elimination. We additionally use the real‐world experience of DAA scale‐up in the Netherlands to illustrate the promise and potential challenges of HCV elimination strategies in MSM. Finally, we summarize key components of the HCV elimination response among PWLH. Results and discussion Modelling indicates HCV elimination among HIV+ MSM and PWID is potentially achievable but requires combination treatment and either harm reduction or behavioural risk reductions. Preliminary modelling indicates elimination among HIV+ PWID will require elimination efforts among PWID more broadly. Treatment for PLWH and high‐risk populations (PWID and MSM) is cost‐effective in high‐income countries, but costs of DAAs remain a barrier to scale‐up worldwide despite the potential low production price ($50 per 12 week course). In the Netherlands, universal DAA availability led to rapid uptake among HIV+ MSM in 2015/16, and a 50% reduction in acute HCV incidence among HIV+ MSM from 2014 to 2016 was observed. In addition to HCV treatment, elimination among PLWH globally also likely requires regular HCV testing, development of low‐cost accurate HCV diagnostics, reduced costs of DAA therapy, broad treatment access without restrictions, close monitoring for HCV reinfection and retreatment, and harm reduction and/or behavioural interventions. Conclusions Achieving WHO HCV Elimination targets is potentially achievable among HIV‐infected populations. Among HIV+ PWID, it likely requires HCV treatment scale‐up combined with harm reduction for both HIV+ and HIV‐ populations. Among HIV+ MSM, elimination likely requires both HCV treatment and behaviour risk reduction among the HIV+ MSM pop

Modelling survival : exposure pattern, species sensitivity and uncertainty

The General Unified Threshold model for Survival (GUTS) integrates previously published toxicokinetic-toxicodynamic models and estimates survival with explicitly defined assumptions. Importantly, GUTS accounts for time-variable exposure to the stressor. We performed three studies to test the ability of GUTS to predict survival of aquatic organisms across different pesticide exposure patterns, time scales and species. Firstly, using synthetic data, we identified experimental data requirements which allow for the estimation of all parameters of the GUTS proper model. Secondly, we assessed how well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates to build species sensitivity distributions for different exposure patterns. We find that GUTS adequately predicts survival across exposure patterns that vary over time. When toxicity is assessed for time-variable concentrations species may differ in their responses depending on the exposure profile. This can result in different species sensitivity rankings and safe levels. The interplay of exposure pattern and species sensitivity deserves systematic investigation in order to better understand how organisms respond to stress, including humans