The respiratory activities of plant roots, of their mycorrhizal fungi and of the free-living microbial heterotrophs (decomposers) in soils are significant components of the global carbon balance, but ...their relative contributions remain uncertain. To separate mycorrhizal root respiration from heterotrophic respiration in a boreal pine forest, we conducted a large-scale tree-girdling experiment, comprising 9 plots each containing about 120 trees. Tree-girdling involves stripping the stem bark to the depth of the current xylem at breast height terminating the supply of current photosynthates to roots and their mycorrhizal fungi without physically disturbing the delicate root-microbe-soil system. Here we report that girdling reduced soil respiration within 1-2 months by about 54% relative to respiration on ungirdled control plots, and that decreases of up to 37% were detected within 5 days. These values clearly show that the flux of current assimilates to roots is a key driver of soil respiration; they are conservative estimates of root respiration, however, because girdling increased the use of starch reserves in the roots. Our results indicate that models of soil respiration should incorporate measures of photosynthesis and of seasonal patterns of photosynthate allocation to roots.
Saccharomyces cerevisiae RecQ helicase, Sgs1, and XPF family endonuclease, Mus81-Mms4, are implicated in processing joint molecule (JM) recombination intermediates. We show that cells lacking either ...enzyme frequently experience chromosome segregation problems during meiosis and that when both enzymes are absent attempted segregation fails catastrophically. In all cases, segregation appears to be impeded by unresolved JMs. Analysis of the DNA events of recombination indicates that Sgs1 limits aberrant JM structures that result from secondary strand-invasion events and often require Mus81-Mms4 for their normal resolution. Aberrant JMs contain high levels of single Holliday junctions and include intersister JMs, multichromatid JMs comprising three and four chromatids, and newly identified recombinant JMs containing two chromatids, one of which has undergone crossing over. Despite persistent JMs in
sgs1 mms4 double mutants, crossover and noncrossover products still form at high levels. We conclude that Sgs1 and Mus81-Mms4 collaborate to eliminate aberrant JMs, whereas as-yet-unidentified enzymes process normal JMs.
This study provides an overview of the coupled high‐resolution Version 1 of the Energy Exascale Earth System Model (E3SMv1) and documents the characteristics of a 50‐year‐long high‐resolution control ...simulation with time‐invariant 1950 forcings following the HighResMIP protocol. In terms of global root‐mean‐squared error metrics, this high‐resolution simulation is generally superior to results from the low‐resolution configuration of E3SMv1 (due to resolution, tuning changes, and possibly initialization procedure) and compares favorably to models in the CMIP5 ensemble. Ocean and sea ice simulation is particularly improved, due to better resolution of bathymetry, the ability to capture more variability and extremes in winds and currents, and the ability to resolve mesoscale ocean eddies. The largest improvement in this regard is an ice‐free Labrador Sea, which is a major problem at low resolution. Interestingly, several features found to improve with resolution in previous studies are insensitive to resolution or even degrade in E3SMv1. Most notable in this regard are warm bias and associated stratocumulus deficiency in eastern subtropical oceans and lack of improvement in El Niño. Another major finding of this study is that resolution increase had negligible impact on climate sensitivity (measured by net feedback determined through uniform +4K prescribed sea surface temperature increase) and aerosol sensitivity. Cloud response to resolution increase consisted of very minor decrease at all levels. Large‐scale patterns of precipitation bias were also relatively unaffected by grid spacing.
Plain Language Summary
The Energy Exascale Earth System Model (E3SM) is a relatively new fully coupled Earth system and climate model used in major international model simulation projects and mission‐defined efforts for the U.S. Department of Energy. This paper describes the first simulation of the model in its high‐resolution configuration. This higher‐resolution version is able to capture the most energetic motions in the ocean, which are poorly represented in standard resolution coupled climate models, as well as the largest of storms in the atmosphere. Evaluation of this simulation confirms the benefits of high resolution found by other models with a few notable exceptions. These discrepancies with other studies are interesting because they provide a richer understanding of how and why resolution affects model bias. Another key finding is that climate and aerosol sensitivity in E3SM is unaffected by resolution change. This affirms the usefulness of coarser‐resolution models for understanding global‐scale climate change. This study also confirms the benefits of increased resolution for studying fine‐scale features such as hurricanes and orographic precipitation. Finally, the high‐resolution version of E3SM is shown to compare favorably to its low‐resolution counterpart and to the models participating in Phase 5 of the Coupled Model Intercomparison Project.
Key Points
The high‐resolution E3SMv1 model was run for 50 years using 1950 forcing data according to the HighResMIP protocol
Higher resolution and associated retuning improved bias relative to coarser versions of E3SMv1, particularly in ocean and sea ice metrics
Aerosol and climate sensitivity were relatively unaffected by resolution change; resolution‐related tuning had a larger impact
We determined baseline oral and cervicogenital human papillomavirus (HPV) prevalence and determinants of infection in the Michigan HPV and Oropharyngeal Cancer (MHOC) study. We enrolled 394 ...college-age and older participants of both sexes in Ann Arbor, Michigan and the surrounding area. All participants provided an oral sample at baseline, and 130 females provided a cervicogenital sample. Samples were tested for 18 HPV genotypes using polymerase chain reaction (PCR) MassArray. Participants filled out sociodemographic and behavioral questionnaires. Prevalence ratios for HPV oral or cervicogenital prevalence by predictor variables were estimated in univariable log-binomial models. Analysis was conducted 2018-20. In the full cohort, baseline oral HPV prevalence was 10.0% for any detected genotype (among the 338 valid oral tests at baseline) and 6.5% for high-risk types, and cervicogenital prevalence was 20.0% and 10.8%, respectively (among the 130 first valid cervicogenital tests). Oral HPV prevalence did not vary by sex, with 10.5% of women and 9.0% of men having an infection. We found a high prevalence of oral and cervicogenital HPV infection in college-age participants reporting no lifetime sexual partners. Reporting a single recent partner was associated with a lower oral HPV prevalence (PR 0.39, 95% CI: 0.16, 0.96) than reporting no recent (but at least one ever) partner. No similar protective effect was seen for cervicogenital HPV. Both oral and cervicogenital prevalence increased with the number of recent partners for most sexual behaviors. We observed an ecological fallacy masking the direction of impact of vaccination on HPV prevalence in the full cohort compared to the college-aged and the age 23+ populations considered separately. Substance use was not significantly associated with oral or cervicogenital HPV infection. Many studies report substantially higher oral HPV infection prevalence in men than in women. That difference may not be uniform across populations in the US.
The Ecology of Genetically Diverse Infections Read, Andrew F.; Taylor, Louise H.
Science (American Association for the Advancement of Science),
05/2001, Letnik:
292, Številka:
5519
Journal Article
Recenzirano
Microparasite infections often consist of genetically distinct clonal lineages. Ecological interactions between these lineages within hosts can influence disease severity, epidemiology, and ...evolution. Many medical and veterinary interventions have an impact on genetic diversity within infections, but there is little understanding of the long-term consequences of such interventions for public and animal health. Indeed, much of the theory in this area is based on assumptions contradicted by the available data.
Aim: Managing fire is critical for the conservation of biodiversity in many ecosystems globally. To manage fire effectively, it is necessary to identify the temporal and spatial scales at which it ...affects a diverse range of species. This information is challenging to obtain for rare and threatened species for which data often are sparse, and in systems with long fire-return intervals (e.g. >100 years). We tested the effects of a century of fires on the distribution of 12 threatened bird species across a 100,000 km² region in which "long-unburnt" vegetation has been identified as important for the diversity of common species. Location: Semi-arid mallee woodlands of south-eastern Australia. Methods: We developed spatially explicit models to identify the effects of fire history and climatic factors on the distribution of 12 threatened bird species, including two globally endangered species, the Mallee Emu-wren (Stipiturus mallee) and Black-eared Miner (Manorina melanotis). Results: Fire was a driver of distribution for all species. Four species were common in younger vegetation (<20 years post-fire) and 11 were most common in mid (20-60 years post-fire) to older (>60 years post-fire) vegetation. Species' distributions were further restricted to areas associated with particular vegetation types and climatic conditions. Main conclusions: Comprehensive investigation of the response to fire by a range of threatened species highlights the importance of what is now recognized as midsuccessional mallee vegetation (20-60 years post-fire), and that species' preferences for previously identified "long-unburnt" vegetation extend to >60 years post-fire. Fire management conducted with incomplete knowledge, or which is focussed on introducing prescribed burns or suppressing fires for early/late-successional species alone, is unlikely to maximize biodiversity. Effective fire management for biodiversity requires the promotion of ecological processes that result in key successional stages at particular locations in the landscape.
Melasma is a chronic hypermelanosis of the skin that affects approximately 1% of the global population, predominantly affects women, and is more prevalent in skin of color. Melasma is a common driver ...for patients with skin of color to seek out a dermatologist for treatment, and ensuring the right approach for these patients is important because some treatments may be associated with adverse side effects. Because of the chronicity of the disease and established psychosocial and emotional impacts, there is a large need to ensure care follows the best available evidence on the treatment of patients with melasma.
Here, we summarized current available topical treatments for melasma with considerations dermatologists should have for their patients with skin of color.
Steering committee consensus on clinical best practices.
We describe a flexible and focused treatment algorithm that reflects both treatment and maintenance periods that is a consensus of our extensive clinical experience.
Use of real-world evidence and potential for individual practice bias.
Melasma can be challenging to treat, particularly in patients with skin of color, and our recommendations for best practices for patients in the United States are an important step toward standardizing care.
Drake Passage is a key region for transport between the surface and interior ocean, but a mechanistic understanding of this exchange remains immature. Here, we present wintertime, ...submesoscale‐resolving hydrographic transects spanning the southern boundary of the Antarctic Circumpolar Current and the Polar Front (PF). Despite the strong surface wind and buoyancy forcing, a freshwater lens suppresses surface‐interior exchange south of the PF; ventilation is instead localized to the PF. Multiple lines of the analysis suggest submesoscale processes contribute to ventilation at the PF, including small‐scale, O(10 km), frontal structure in water mass properties below the mixed layer and modulation of a surface eddy diffusivity at sub‐50 km scales. These results show that ventilation is sensitive to both submesoscale properties near fronts and non‐local processes, for example, sea‐ice melt, that set stratification and mixed layer properties. This highlights the need for adaptive observing strategies to constrain Southern Ocean heat and carbon budgets.
Plain Language Summary
Drake Passage is a region of the Southern Ocean between the southern tip of South America and the Antarctic Peninsula. Due to its relative accessibility as compared to the rest of the polar ocean, it is the most frequently occupied region of the Southern Ocean. Most occupations by ships in Drake Passage acquire measurements at 20–100 km spacing or “mesoscale” resolution. Here, we present data collected by piloted robotic underwater vehicles that sampled across the southern section of Drake Passage with submesoscale, or 1–10 km, resolution in wintertime. These novel observations indicate that while the southernmost region of Drake Passage is strongly stratified in density, the Polar Front (PF), one of the major dynamical features of the Southern Ocean, is more weakly stratified. The reduced stratification at the PF presents a pathway for the localized exchange of water between the surface and interior ocean. In addition, this study finds that the PF is eddy‐suppressing, meaning that the mean flow of the PF can transport oceanic properties away before they can be stirred. These findings have implications for the estimation of carbon fluxes between the atmosphere and the Southern Ocean, a vital part of the climate system.
Key Points
High‐resolution hydrographic sections across the Drake Passage provide insight into spatial variability in surface‐interior exchange
Wintertime observations suggest ventilation is spatially localized to the Polar Front and influenced by submesoscale processes
A mixing length estimate shows modulation at submesoscales and mixing suppression in the upper layers of the Polar Front
Improving population health requires a focus on neighborhoods with high rates of illness. We aimed to reduce hospital days for children from two high-morbidity, high-poverty neighborhoods in ...cincinnati, Ohio, to narrow the gap between their neighborhoods and healthier ones. We also sought to use this population health improvement initiative to develop and refine a theory for how to narrow equity gaps across broader geographic areas. We relied upon quality improvement methods and a learning health system approach. Interventions included the optimization of chronic disease management; transitions in care; mitigation of social risk; and use of actionable, realtime data. The inpatient bed-day rate for the two target neighborhoods decreased by 18 percent from baseline (July 2012-June 2015) to the improvement phase (July 2015-June 2018). Hospitalizations decreased by 20 percent. There was no similar decrease in demographically comparable neighborhoods. We see the neighborhood as a relevant frame for achieving equity and building a multisector culture of health.
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