Woody-plant encroachment: Precipitation, herbivory, and grass-competition interact to affect shrub recruitment.

Woody-plant encroachment is a global phenomenon that has been affecting the southwestern United States since the late 1800s. Drought, overgrazing, herbivory, and competition between grasses and shrub seedlings have been hypothesized as the main drivers of shrub establishment. However, there is limited knowledge about the interactions among these drivers. Using a rainfall manipulation system and various herbivore exclosures, we tested hypotheses about how precipitation (PPT), competition between grasses and shrub seedlings, and predation affect the germination and first-year survival of mesquite (Prosopis glandulosa), a shrub that has encroached in Southern Great Plains and Chihuahuan Desert grasslands. We found that mesquite germination and survival (1) increased with increasing PPT, then saturated at about the mean growing season PPT level, (2) that competition between grasses and shrub seedlings had no effect on either germination or survival, and (3) that herbivory by small mammals decreased seedling establishment and survival, while ant granivory showed no effect. In addition to its direct positive effect on survival, PPT had an indirect negative effect via increasing small mammal activity. Current models predict a decrease in PPT in the southwestern United States with increased frequency of extreme events. The non-linear nature of PPT effects on Mesquite recruitment suggests asymmetric responses, wherein drought has a relatively greater negative effect than the positive effect of wet years. Indirect effects of PPT, through its effects on small mammal abundance, highlight the importance of accounting for interactions between biotic and abiotic drivers of shrub encroachment. This study provides quantitative basis for developing tools that can inform effective shrub management strategies in grasslands and savannas.

Rationale, Methodological Quality, and Reporting of Cluster-Randomized Controlled Trials in Critical Care Medicine: A Systematic Review.

OBJECTIVE: Compared with individual-patient randomized controlled trials, cluster randomized controlled trials have unique methodological and ethical considerations. We evaluated the rationale, methodological quality, and reporting of cluster randomized controlled trials in critical care studies. DATA SOURCES: Systematic searches of Medline, Embase, and Cochrane Central Register were performed. STUDY SELECTION: We included all cluster randomized controlled trials conducted in adult, pediatric, or neonatal critical care units from January 2005 to September 2019. DATA EXTRACTION: Two reviewers independently screened citations, reviewed full texts, protocols, and supplements of potentially eligible studies, abstracted data, and assessed methodology of included studies. DATA SYNTHESIS: From 1,902 citations, 59 cluster randomized controlled trials met criteria. Most focused on quality improvement (24, 41%), antimicrobial therapy (9, 15%), or infection control (9, 15%) interventions. Designs included parallel-group (25, 42%), crossover (21, 36%), and stepped-wedge (13, 22%). Concealment of allocation was reported in 21 studies (36%). Thirteen studies (22%) reported at least one method of blinding. The median total sample size was 1,660 patients (interquartile range, 813-4,295); the median number of clusters was 12 (interquartile range, 5-24); and the median patients per cluster was 141 (interquartile range, 54-452). Sample size calculations were reported in 90% of trials, but only 54% met Consolidated Standards of Reporting Trials guidance for sample size reporting. Twenty-seven of the studies (46%) identified a fixed number of available clusters prior to trial commencement, and only nine (15%) prespecified both the number of clusters and patients required to detect the expected effect size. Overall, 36 trials (68%) achieved the total prespecified sample size. When analyzing data, 44 studies (75%) appropriately adjusted for clustering when analyzing the primary outcome. Only 12 (20%) reported an intracluster coefficient (median 0.047 [interquartile range, 0.01-0.13]). CONCLUSIONS: Cluster randomized controlled trials in critical care typically involve a small and fixed number of relatively large clusters. The reporting of key methodological aspects of these trials is often inadequate.

Impact of Saccharomyces cerevisiae and Lactobacillus buchneri on microbial communities during ensiling and aerobic spoilage of corn silage1.

The objective of this study was to assess the impact of Saccharomyces cerevisiae in combination with Lactobacillus buchneri on the fermentation characteristics, aerobic stability, nutritive value, and microbial communities of corn silage. Whole crop corn (39% DM) was either uninoculated (Control) or inoculated with S. cerevisiae and L. buchneri at the following concentrations: S. cerevisiae 104 cfu/g fresh forage (S4), S. cerevisiae 105 cfu/g (S5), S. cerevisiae 104 cfu/g + L. buchneri 105 cfu/g (S4L5), and S. cerevisiae 105 cfu/g + L. buchneri 104 cfu/g (S5L4), and ensiled in mini silos for 118 d, followed by 7 d of aerobic exposure. Changes in fermentation characteristics and nutritive value were assessed in terminal silages. Saccharomyces cerevisiae, L. buchneri, and total yeast, fungal, and bacterial communities in silage were estimated using quantitative PCR. Composition of bacterial and fungal communities during ensiling and aerobic exposure was measured using 16S rDNA and ITS sequencing, respectively. In the first 7 d of ensiling, the concentration of lactic acid rapidly increased (P < 0.01) in all silages, with the pH declining to 4.0 (P < 0.001) and thereafter remaining stable (P = 0.23). Although S4L5 contained a higher (P = 0.03) concentration of acetic acid than Control, other fermentation characteristics were did not differ among terminal silages. Inoculation with S. cerevisiae had no detrimental effect on the aerobic stability of silage, whereas L. buchneri did not prevent spoilage as the pH across all silages averaged 8.0 after 7 d of aerobic exposure. Total yeast (P = 0.42), bacterial (P = 0.13), and fungal (P = 0.89) communities were not altered by the inoculants after ensiling or aerobic exposure. Sequencing identified temporal shifts of bacterial and fungal communities during ensiling and aerobic exposure. Concentrations of S. cerevisiae and L. buchneri in all inoculated silages remained greater (P < 0.01) than Control after ensiling, with numbers of S. cerevisiae increasing after 7 d of aerobic exposure. Bacterial communities in silages inoculated with S. cerevisiae and L. buchneri clustered separately from other silages, an observation that was not apparent for fungal communities. Our findings suggest that aerobic exposure could potentially increase the abundance of S. cerevisiae with probiotic properties in corn silage just prior to feeding.

A multimodal, evidence-based approach to achieve lipid targets in the treatment of antiretroviral-associated dyslipidemia: case report and review of the literature.

Metabolic abnormalities associated with the treatment of human immunodeficiency virus (HIV) infection are well-recognized problems that increase cardiovascular risk. As a result of the complexity of treating both HIV- and antiretroviral-related comorbidities, strategies that improve adverse drug events while maintaining viral control are in critical need. Although guidelines have somewhat helped in the general approach and in first-line strategies for managing dyslipidemia in patients receiving antiretrovirals, a paucity of data exist to guide clinicians in treating patients whose conditions are refractory to first-line options or who are at substantial risk for cardiovascular events. Further complicating the choice of lipid-lowering strategy is the lack of randomized controlled data from the HIV-affected population and a concern about clinically significant drug-drug interactions. We describe an HIV-infected patient with efavirenz-associated dyslipidemia at very high cardiovascular risk who had not achieved his primary or secondary lipid goals despite 2 years of treatment in a lipid specialty clinic. Lipid control was accomplished in 10 weeks with a targeted, stepwise approach of switching efavirenz to nevirapine, followed by rosuvastatin 20 mg/day, which was sustained for at least 10 months. Of most importance, this outcome was achieved without any clinically significant alteration in virologic or immunologic control. This case report highlights the potential for a pharmacist-guided, multistep approach that addresses HIV-related dyslipidemia and incorporates the pharmacokinetic literature to guide lipid-lowering therapy and promote the attainment of goals based on current standards of care.

Albedo feedbacks to future climate via climate change impacts on dryland biocrusts.

Drylands represent the planet's largest terrestrial biome and evidence suggests these landscapes have large potential for creating feedbacks to future climate. Recent studies also indicate that dryland ecosystems are responding markedly to climate change. Biological soil crusts (biocrusts) ‒ soil surface communities of lichens, mosses, and/or cyanobacteria ‒ comprise up to 70% of dryland cover and help govern fundamental ecosystem functions, including soil stabilization and carbon uptake. Drylands are expected to experience significant changes in temperature and precipitation regimes, and such alterations may impact biocrust communities by promoting rapid mortality of foundational species. In turn, biocrust community shifts affect land surface cover and roughness-changes that can dramatically alter albedo. We tested this hypothesis in a full-factorial warming (+4 °C above ambient) and altered precipitation (increased frequency of 1.2 mm monsoon-type watering events) experiment on the Colorado Plateau, USA. We quantified changes in shortwave albedo via multi-angle, solar-reflectance measurements. Warming and watering treatments each led to large increases in albedo (>30%). This increase was driven by biophysical factors related to treatment effects on cyanobacteria cover and soil surface roughness following treatment-induced moss and lichen mortality. A rise in dryland surface albedo may represent a previously unidentified feedback to future climate.

Metabarcoding avian diets at airports: implications for birdstrike hazard management planning.

BACKGROUND: Wildlife collisions with aircraft cost the airline industry billions of dollars per annum and represent a public safety risk. Clearly, adapting aerodrome habitats to become less attractive to hazardous wildlife will reduce the incidence of collisions. Formulating effective habitat management strategies relies on accurate species identification of high-risk species. This can be successfully achieved for all strikes either through morphology and/or DNA-based identifications. Beyond species identification, dietary analysis of birdstrike gut contents can provide valuable intelligence for airport hazard management practices in regards to what food is attracting which species to aerodromes. Here, we present birdstrike identification and dietary data from Perth Airport, Western Australia, an aerodrome that saw approximately 140,000 aircraft movements in 2012. Next-generation high throughput DNA sequencing was employed to investigate 77 carcasses from 16 bird species collected over a 12-month period. Five DNA markers, which broadly characterize vertebrates, invertebrates and plants, were used to target three animal mitochondrial genes (12S rRNA, 16S rRNA, and COI) and a plastid gene (trnL) from DNA extracted from birdstrike carcass gastrointestinal tracts. RESULTS: Over 151,000 DNA sequences were generated, filtered and analyzed by a fusion-tag amplicon sequencing approach. Across the 77 carcasses, the most commonly identified vertebrate was Mus musculus (house mouse). Acrididae (grasshoppers) was the most common invertebrate family identified, and Poaceae (grasses) the most commonly identified plant family. The DNA-based dietary data has the potential to provide some key insights into feeding ecologies within and around the aerodrome. CONCLUSIONS: The data generated here, together with the methodological approach, will greatly assist in the development of hazard management plans and, in combination with existing observational studies, provide an improved way to monitor the effectiveness of mitigation strategies (for example, netting of water, grass type, insecticides and so on) at aerodromes. It is hoped that with the insights provided by dietary data, airports will be able to allocate financial resources to the areas that will achieve the best outcomes for birdstrike reduction.

BMI-referenced standards for recommended pedometer-determined steps/day in children.

BACKGROUND: Recommended levels of youth physical activity (PA) should emerge from data related to important health outcomes. The purpose of the present study was to establish criterion-referenced standards for PA (using pedometer-assessed steps/day) related to healthy body composition. METHODS: This is a secondary analysis of an existing data set (including pedometer-assessed PA and objectively measured BMI) of 1,954 children (995 girls, 959 boys; ages 6-12 years) from the USA, Australia, and Sweden. The contrasting groups method [M.J. Sarif, Introduction to Measurement in Physical Education and Exercise Science, St. Louis, MO: Mosby College Publishing; 1986] for establishing criterion-referenced cut points was used to identify optimal age- and sex-specific standards for steps/day related to international BMI cut points for normal weight and overweight/obesity. RESULTS: The selected cut points for steps/day for 6-12 year olds were 12,000 steps/day for girls and 15,000 steps/day for boys. CONCLUSIONS: The analytical process undertaken in this study illuminated the difference in previously used norm-referenced standards vs. criterion-referenced standards based on BMI categories. The steps/day cut points established herein, using an international sample, are higher than previously suggested normative standards but are not inconsistent with recent advances in our understanding of PA needs in youth. This analysis provides the foundation for cross-validation and evaluation of these BMI-referenced steps/day cut points in independent samples and with longitudinal study designs.

The medical severity index of disasters

In 1980 an international working party postulated a definition for a disaster. later this concept was formulated into a classification and scoring system. This system has now been refined to be used prospectively during the management stage of a calamity. By calculating the medical severity index, which is the product of the casualty load and the severity of the incident, and comparing this figure with the available total capacity of the medical services, which is the medical rescue capacity, the medical transport capacity and the hospital treatment capacity, the dispatcher at the control center can fairly quickly and precisely identify if a calamity is to be regarded as a disaster or not and if the region can cope with the situation. Moreover a calculation of the hospital treatment capacity in the dimensions needed for the medical rescue capacity and medical transport capcity when planning how to deal with a disaster.(AU)