A circumpolar study unveils a positive non-linear effect of temperature on arctic arthropod availability that may reduce the risk of warming-induced trophic mismatch for breeding shorebirds.

Seasonally abundant arthropods are a crucial food source for many migratory birds that breed in the Arctic. In cold environments, the growth and emergence of arthropods are particularly tied to temperature. Thus, the phenology of arthropods is anticipated to undergo a rapid change in response to a warming climate, potentially leading to a trophic mismatch between migratory insectivorous birds and their prey. Using data from 19 sites spanning a wide temperature gradient from the Subarctic to the High Arctic, we investigated the effects of temperature on the phenology and biomass of arthropods available to shorebirds during their short breeding season at high latitudes. We hypothesized that prolonged exposure to warmer summer temperatures would generate earlier peaks in arthropod biomass, as well as higher peak and seasonal biomass. Across the temperature gradient encompassed by our study sites (>10°C in average summer temperatures), we found a 3-day shift in average peak date for every increment of 80 cumulative thawing degree-days. Interestingly, we found a linear relationship between temperature and arthropod biomass only below temperature thresholds. Higher temperatures were associated with higher peak and seasonal biomass below 106 and 177 cumulative thawing degree-days, respectively, between June 5 and July 15. Beyond these thresholds, no relationship was observed between temperature and arthropod biomass. Our results suggest that prolonged exposure to elevated temperatures can positively influence prey availability for some arctic birds. This positive effect could, in part, stem from changes in arthropod assemblages and may reduce the risk of trophic mismatch.

Why do avian responses to change in Arctic green-up vary?

Global climate change has altered the timing of seasonal events (i.e., phenology) for a diverse range of biota. Within and among species, however, the degree to which alterations in phenology match climate variability differ substantially. To better understand factors driving these differences, we evaluated variation in timing of nesting of eight Arctic-breeding shorebird species at 18 sites over a 23-year period. We used the Normalized Difference Vegetation Index as a proxy to determine the start of spring (SOS) growing season and quantified relationships between SOS and nest initiation dates as a measure of phenological responsiveness. Among species, we tested four life history traits (migration distance, seasonal timing of breeding, female body mass, expected female reproductive effort) as species-level predictors of responsiveness. For one species (Semipalmated Sandpiper), we also evaluated whether responsiveness varied across sites. Although no species in our study completely tracked annual variation in SOS, phenological responses were strongest for Western Sandpipers, Pectoral Sandpipers, and Red Phalaropes. Migration distance was the strongest additional predictor of responsiveness, with longer-distance migrant species generally tracking variation in SOS more closely than species that migrate shorter distances. Semipalmated Sandpipers are a widely distributed species, but adjustments in timing of nesting relative to variability in SOS did not vary across sites, suggesting that different breeding populations of this species were equally responsive to climate cues despite differing migration strategies. Our results unexpectedly show that long-distance migrants are more sensitive to local environmental conditions, which may help them to adapt to ongoing changes in climate.

Frailty trajectories preceding dementia: an individual-level analysis of four cohort studies in the United States and United Kingdom.

Frailty may represent a modifiable risk factor for dementia, but the direction of that association remains uncertain. We investigated frailty trajectories in the years preceding dementia onset using data from 23,672 participants (242,760 person-years of follow-up, 2,906 cases of incident dementia) across four cohort studies in the United States and United Kingdom. Bayesian non-linear models revealed accelerations in frailty trajectories 4-9 years before incident dementia. Among participants whose time between frailty measurement and incident dementia exceeded that prodromal period, frailty remained positively associated with dementia risk (adjusted hazard ratios ranged from 1.20 [95% confidence interval, CI = 1.15-1.26] to 1.43 [95% CI = 1.14-1.81]). This observational evidence suggests that frailty increases dementia risk independently of any reverse causality. These findings indicate that frailty measurements can be used to identify high-risk population groups for preferential enrolment into clinical trials for dementia prevention and treatment. Frailty itself may represent a useful upstream target for behavioural and societal approaches to dementia prevention.

Reducing the Frequency of Surveillance Blood Work in Patients Treated With Maintenance Hemodialysis: A Local Quality Improvement Initiative.

Introduction: There is little evidence on the ideal frequency of routine blood work in maintenance dialysis patients to manage complications, including anemia, mineral bone disease (MBD), and hyperkalemia. Recent quality improvement studies from Ontario showed no negative impacts when decreasing the frequency from monthly to every 6 weeks in conventional in-center hemodialysis (ICHD) patients. In December 2020, Alberta Kidney Care-South (AKC-S) reduced the frequency of routine blood work from every 6 weeks to every 8 weeks for ICHD patients. Objective: We aimed to assess the impact of reducing blood work frequency on patient outcomes. Methods: We compared prevalent AKC-S ICHD patients in 2 cohorts: (1) retrospective control (October 31, 2019-October 31, 2020) and (2) prospective intervention (December 1, 2020-December 1, 2021). Primary outcomes were true frequency of routine blood work, odds of patients being within target for anemia and MBD, and proportion of lab values of hyperkalemia. Furthermore, we compared hospitalizations and mortality. Results: A total of 972 patients in Calgary's ICHD program were included, 787 in each period (with 602 patients overlapping both cohorts). The frequency of routine blood work decreased from every 39.5 days in the control period to every 54.2 days in the intervention period (P < .01). There was a reduction in the odds of phosphate values in targets (P = .02), and an increase in the odds of labs with hyperkalemia (>6.0 mmol/L) during the intervention period (P = .01). There was no significant change in the odds of being within the accepted targets during the intervention period compared with the control period for hemoglobin, Tsat, calcium, or parathyroid hormone (PTH). Fewer patients were hospitalized during the intervention period and the risk of death decreased as well, although additional factors such as the COVID-19 pandemic may have affected this. A cost-savings of $32 962 occurred from the reduced anemia and MBD blood work during the intervention period. Conclusions: When ICHD units in Calgary reduced routine blood work frequency from every 6 weeks to 8 weeks, there were no negative impacts on hospitalizations or deaths. A slightly lower proportion of phosphate values were within target, and a 0.7% increase in potassium values greater than 6 mmol/L was demonstrated. Our study suggests that blood work frequency in ICHD dialysis patients may be further reduced to every 8 weeks safely. Ultimately, additional pragmatic trials are needed to identify the optimal frequency of routine blood work.

Introduction: Il existe peu de données quant à la fréquence idéale des analyses sanguines chez les patients sous dialyse d'entretien pour gérer les complications comme l'anémie, les troubles liés à la densité osseuse (TDO) et l'hyperkaliémie. De récentes études d'amélioration de la qualité menées en Ontario n'ont montré aucune conséquence négative lorsque la fréquence des analyses des patients traités de façon traditionnelle par hémodialyse en centre (HDC) est passée d'une fois par mois à une fois toutes les 6 semaines. L'Alberta Kidney Care-South (AKC-S) a réduit la fréquence des analyses sanguines de routine; depuis décembre 2020, les analyses des patients traités par HDC sont effectuées toutes les 8 semaines plutôt qu'aux 6 semaines. Objectif: Évaluer les effets d'une réduction de la fréquence des analyses sanguines sur les résultats des patients. Méthodologie: Nous avons comparé des patients de l'AKC-S prévalents pour l'HDC dans deux cohortes: a) période témoin ­ rétrospective (31 octobre 2019 au 31 octobre 2020); b) période d'intervention ­ prospective (1er décembre 2020 au 1er décembre 2021). Les principaux critères d'évaluation étaient la fréquence réelle des analyses sanguines de routine, la probabilité que les patients soient dans la cible pour l'anémie et les TDO, et dans la fourchette cible des valeurs de laboratoire pour l'hyperkaliémie. Les hospitalisations et la mortalité ont également été comparées entre les deux cohortes. Résultats: Au total, 972 patients du programme d'HDC de Calgary ont été inclus, soit deux cohortes de 787 patients (602 patients ont chevauché les deux cohortes). Les analyses sanguines étaient effectuées tous les 39,5 jours pendant la période témoin; cette fréquence est passée aux 54,2 jours pendant la période d'intervention (p<0,01). On a observé une réduction des probabilités que le taux de phosphate soit dans les cibles (p=0,02) et une augmentation des valeurs de laboratoire montrant une hyperkaliémie (>6,0 mmol/L) pendant la période d'intervention (p=0,01). Aucun changement significatif n'a été observé entre les deux périodes en ce qui concerne la probabilité que les valeurs de laboratoire soient dans les cibles acceptées pour l'hémoglobine, le TSAT, le calcium ou la PTH. Pendant la période d'intervention, moins de patients ont été hospitalisés et le risque de décès a diminué, mais d'autres facteurs, notamment la pandémie de COVID-19, ont pu influer sur ce résultat. Enfin, le fait de réduire la fréquence des analyses de suivi pour l'anémie et les TDO a entraîné des économies de 32 962 $. Conclusion: Aucune conséquence négative n'a été observée lorsque la fréquence des analyses sanguines des patients des unités d'hémodialyse en centre de Calgary est passée de 6 à 8 semaines. Une proportion légèrement plus faible des valeurs de phosphate se situait dans la fourchette cible et une augmentation de 0,7 % des valeurs de potassium supérieures à 6 mmol/L a été constatée. Notre étude suggère qu'il est sécuritaire d'effectuer les analyses sanguines des patients hémodialysés en centre toutes les 8 semaines. Des essais pragmatiques sont nécessaires pour déterminer la fréquence optimale de ces analyses.

Where east meets west: Phylogeography of the high Arctic North American brant goose.

Genetic variation in Arctic species is often influenced by vicariance during the Pleistocene, as ice sheets fragmented the landscape and displaced populations to low- and high-latitude refugia. The formation of secondary contact or suture zones during periods of ice sheet retraction has important consequences on genetic diversity by facilitating genetic connectivity between formerly isolated populations. Brant geese (Branta bernicla) are a maritime migratory waterfowl (Anseriformes) species that almost exclusively uses coastal habitats. Within North America, brant geese are characterized by two phenotypically distinct subspecies that utilize disjunct breeding and wintering areas in the northern Pacific and Atlantic. In the Western High Arctic of Canada, brant geese consist of individuals with an intermediate phenotype that are rarely observed nesting outside this region. We examined the genetic structure of brant geese populations from each subspecies and areas consisting of intermediate phenotypes using mitochondrial DNA (mtDNA) control region sequence data and microsatellite loci. We found a strong east-west partition in both marker types consistent with refugial populations. Within subspecies, structure was also observed at mtDNA while microsatellite data suggested the presence of only two distinct genetic clusters. The Western High Arctic (WHA) appears to be a secondary contact zone for both Atlantic and Pacific lineages as mtDNA and nuclear genotypes were assigned to both subspecies, and admixed individuals were observed in this region. The mtDNA sequence data outside WHA suggests no or very restricted intermixing between Atlantic and Pacific wintering populations which is consistent with published banding and telemetry data. Our study indicates that, although brant geese in the WHA are not a genetically distinct lineage, this region may act as a reservoir of genetic diversity and may be an area of high conservation value given the potential of low reproductive output in this species.

Delirium and incident dementia in hospital patients in New South Wales, Australia: retrospective cohort study.

OBJECTIVES: To determine the strength and nature of the association between delirium and incident dementia in a population of older adult patients without dementia at baseline. DESIGN: Retrospective cohort study using large scale hospital administrative data. SETTING: Public and private hospitals in New South Wales, Australia between July 2001 and March 2020. PARTICIPANTS: Data were extracted for 650 590 hospital patients aged ≥65 years. Diagnoses of dementia and delirium were identified from ICD-10 (international classification of diseases, 10th revision) codes. Patients with dementia at baseline were excluded. Delirium-no delirium pairs were identified by matching personal and clinical characteristics, and were followed for more than five years. MAIN OUTCOME MEASURES: Cox proportional hazards models and Fine-Gray hazard models were used to estimate the associations of delirium with death and incident dementia, respectively. Delirium-outcome dose-response associations were quantified, all analyses were performed in men and women separately, and sensitivity analyses were conducted. RESULTS: The study included 55 211 matched pairs (48% men, mean age 83.4 years, standard deviation 6.5 years). Collectively, 58% (n=63 929) of patients died and 17% (n=19 117) had a newly reported dementia diagnosis during 5.25 years of follow-up. Patients with delirium had 39% higher risk of death (hazard ratio 1.39, 95% confidence interval 1.37 to 1.41) and three times higher risk of incident dementia (subdistribution hazard ratio 3.00, 95% confidence interval 2.91 to 3.10) than patients without delirium. The association with dementia was stronger in men (P=0.004). Each additional episode of delirium was associated with a 20% increased risk of dementia (subdistribution hazard ratio 1.20, 95% confidence interval 1.18 to 1.23). CONCLUSIONS: The study findings suggest delirium was a strong risk factor for death and incident dementia among older adult patients. The data support a causal interpretation of the association between delirium and dementia. The clinical implications of delirium as a potentially modifiable risk factor for dementia are substantial.

Experimental Characterization of Defect-Induced Phonon Lifetime Shortening.

We present the first direct experimental measurement of defect-induced lifetime shortening of acoustic surface phonons. Defects are found to contribute a temperature-independent component to the linewidths of Rayleigh wave phonons on a Ni(111) surface. We also characterized the increase in phonon scattering with both surface defect density and phonon wave vector. A quantitative estimate of the scattering rate between phonon modes and surface line defects is extracted from the experimental data for the first time.

Single-molecular diffusivity and long jumps of large organic molecules: CoPc on Ag(100).

Energy dissipation and the transfer rate of adsorbed molecules do not only determine the rates of chemical reactions but are also a key factor that often dictates the growth of organic thin films. Here, we present a study of the surface dynamical motion of cobalt phthalocyanine (CoPc) on Ag(100) in reciprocal space based on the helium spin-echo technique in comparison with previous scanning tunnelling microscopy studies. It is found that the activation energy for lateral diffusion changes from 150 meV at 45-50 K to ≈100 meV at 250-350 K, and that the process goes from exclusively single jumps at low temperatures to predominantly long jumps at high temperatures. We thus illustrate that while the general diffusion mechanism remains similar, upon comparing the diffusion process over widely divergent time scales, indeed different jump distributions and a decrease of the effective diffusion barrier are found. Hence a precise molecular-level understanding of dynamical processes and thin film formation requires following the dynamics over the entire temperature scale relevant to the process. Furthermore, we determine the diffusion coefficient and the atomic-scale friction of CoPc and establish that the molecular motion on Ag(100) corresponds to a low friction scenario as a consequence of the additional molecular degrees of freedom.

Frailty is associated with the clinical expression of neuropsychological deficits in older adults.

BACKGROUND AND PURPOSE: The aim was to determine whether frailty is associated with the relationship between neuropsychological markers and global cognition in older adults. METHODS: Cross-sectional analyzes were conducted of baseline data from three large cohort studies: National Alzheimer's Coordinating Center (NACC), Rush Memory and Aging Project (MAP) and Alzheimer's Disease Neuroimaging Initiative (ADNI). Studies recruited North American participants along the spectrum of cognitive functioning (44% no cognitive impairment at baseline). A frailty index was computed in each dataset. Frailty indices, neuropsychological tests (including measures of processing speed, episodic, semantic and working memory) and Mini-Mental State Examination (MMSE) scores were the variables of interest, with age, sex, education and apolipoprotein E ε4 evaluated as confounders. RESULTS: Across all studies, 23,819 participants aged 55-104 (57% female) were included in analyzes. Frailty index scores were significantly and inversely associated with MMSE scores and significantly moderated relationships between neuropsychological test scores and MMSE scores. In participants with higher frailty index scores, lower neuropsychological test scores were more strongly associated with lower MMSE scores (standardized interaction coefficients ranged from -0.19 to -1.17 in NACC, -0.03 to -2.27 in MAP and -0.04 to -0.38 in ADNI, depending on the neuropsychological test). These associations were consistent across the different databases and were mostly independent of the composition of frailty indices (i.e., after excluding possible symptoms of dementia). CONCLUSIONS: Amongst older Americans, frailty is associated with the cognitive expression of neuropsychological deficits. Implementation of frailty assessment in routine neurological and neuropsychological practice should be considered to optimize care outcomes for older adults.

Investigating Sex Differences in Risk and Protective Factors in the Progression of Mild Cognitive Impairment to Dementia: A Systematic Review.

BACKGROUND: Developing effective strategies for reducing dementia risk requires a detailed understanding of the risk and protective factors associated with the progression of mild cognitive impairment (MCI) to dementia. OBJECTIVE: We aimed to systematically review the evidence for sex differences in these factors. METHODS: Five online databases (PubMed/CINAHL/EMBASE/PsycINFO/Cochrane) were searched from inception until 17 October 2022 for cohort studies that focused on sex differences in risk and protective factors in the progression of MCI to dementia. RESULTS: A total of 2,972 studies were identified, of which 12 studies from five countries were included in the systematic review. There was substantial variability in study designs, study populations and outcome measures. Sex differences were present in the associations of sociodemographic, health, psychological factors, genetic and other biomarkers with the progression of MCI to dementia. APOE ɛ4 status and depression appeared to increase the risk of progression for females, whereas history of stroke, MRI markers and cerebrospinal fluid biomarkers appeared to increase the risk of progression for males. APOE ɛ2 status and marital status (unmarried) were observed to reduce risk of progression in males and females, respectively. CONCLUSIONS: The ability of studies to accurately detail risk factors for dementia are likely limited when solely controlling for the effects of sex. Although the heterogeneity and underpowered nature of the studies made it difficult to synthesize the findings for each risk factor, this study highlights the apparent need for further research examining risk factors for dementia in males and females with MCI separately.

Eastern redcedar roots create legacy effects that suppresses growth of prairie species.

The expansion of woody species from their historical ranges into grasslands is a global problem. Understanding the mechanisms that enable species to successfully establish and then re-encroach following their removal is critical to effectively managing problem species. Legacy effects are a mechanism that could be critical to the reestablishment of woody encroachers following their removal. Legacy effects occur when a species alters the biotic and abiotic environment in a way that affects communities that establish subsequently. In this study, we assess whether the eastern redcedar (Juniperus virginiana), a North American woody encroacher, generates legacy effects that affect communities that establish following removal of this species from an experimental grass community. We conducted a series of experiments to evaluate the effects of J. virginiana, roots on the germination and growth of grasses and to determine if the effects of root-addition treatments were derived from a microbial or allelopathic origin. Aqueous extracts of J. virginiana roots were found to inhibit the germination of grasses. We found escalating suppression of overall community biomass and the biomass of each individual species with increasing root treatments. Finally, we determined the origin of the observed suppressive effect is unlikely to be of microbial origin. Synthesis: Our results suggest that J. virginiana exudes an allelochemical into soils that inhibits the growth of certain grasses and thus has the potential to have legacy effects on future occupants. We suggest that the inhibition of the development of grasses in areas where J. virginiana has been removed is a mechanism that may favor the reestablishment of J. virginiana. Our results indicate the legacy effects of J. virginiana must be considered when conducting removal and restoration of J. virginiana infested lands.

Geographic and Ecological Diversity of Green Sulfur Bacteria in Hot Spring Mat Communities.

Three strains of thermophilic green sulfur bacteria (GSB) are known; all are from microbial mats in hot springs in Rotorua, New Zealand (NZ) and belong to the species Chlorobaculum tepidum. Here, we describe diverse populations of GSB inhabiting Travel Lodge Spring (TLS) (NZ) and hot springs ranging from 36.1 °C to 51.1 °C in the Republic of the Philippines (PHL) and Yellowstone National Park (YNP), Wyoming, USA. Using targeted amplification and restriction fragment length polymorphism analysis, GSB 16S rRNA sequences were detected in mats in TLS, one PHL site, and three regions of YNP. GSB enrichments from YNP and PHL mats contained small, green, nonmotile rods possessing chlorosomes, chlorobactene, and bacteriochlorophyll c. Partial 16S rRNA gene sequences from YNP, NZ, and PHL mats and enrichments from YNP and PHL samples formed distinct phylogenetic clades, suggesting geographic isolation, and were associated with samples differing in temperature and pH, suggesting adaptations to these parameters. Sequences from enrichments and corresponding mats formed clades that were sometimes distinct, increasing the diversity detected. Sequence differences, monophyly, distribution patterns, and evolutionary simulation modeling support our discovery of at least four new putative moderately thermophilic Chlorobaculum species that grew rapidly at 40 °C to 44 °C.

2D Helium Atom Diffraction from a Microscopic Spot.

A method for measuring helium atom diffraction with micron-scale spatial resolution is demonstrated in a scanning helium microscope (SHeM) and applied to study a micron-scale spot on the (100) plane of a lithium fluoride (LiF) crystal. The positions of the observed diffraction peaks provide an accurate measurement of the local lattice spacing, while a combination of close-coupled scattering calculations and Monte Carlo ray-tracing simulations reproduce the main variations in diffracted intensity. Subsequently, the diffraction results are used to enhance image contrast by measuring at different points in reciprocal space. The results open up the possibility for using helium microdiffraction to characterize the morphology of delicate or electron-sensitive materials on small scales. These include many fundamentally and technologically important samples which cannot be studied in conventional atom scattering instruments, such as small grain size exfoliated 2D materials, polycrystalline samples, and other surfaces that do not exhibit long-range order.

Resprouting Response among Savanna Tree Species in Relation to Stem Size, Woody Removal Intensity and Herbicide Application.

Mechanical and chemical methods are widely used to control woody plant encroachment in many African countries. However, very little is known about the effectiveness of these control methods among woody species of different ages. We conducted a field experiment to determine the effects of different tree removal treatments (10%, 20%, 50%, 75% and 100%) and herbicide application (Picloram; 6 mL L-1) on the resprouting ability and vigour of 12 woody plant species. We examined 20 plots (30 m × 30 m) that were each subjected to tree removal, followed by herbicide application on half of the stems for each plot. All the tree species in this study resprouted after cutting. The applied concentration of herbicide significantly reduced the shoot production for Ehretia rigida, Vachellia robusta and Ziziphus mucronata, with a marginal effect for Dichrostachys cinerea. The diameter of stems was an important factor in determining resprouting ability, with shoot production decreasing with increasing stem diameter. However, stem diameter did not affect shoot length and diameter for all species. We found that woody plants are more likely to resprout and survive as juveniles than as adults after cutting and that herbicide only affected four of the twelve species at a concentration of 6 mL L-1. Thus, testing the amount of Picloram needed to kill certain woody species may be of importance for land users in southern African savannas.

Ocean current patterns drive the worldwide colonization of eelgrass (Zostera marina).

Currents are unique drivers of oceanic phylogeography and thus determine the distribution of marine coastal species, along with past glaciations and sea-level changes. Here we reconstruct the worldwide colonization history of eelgrass (Zostera marina L.), the most widely distributed marine flowering plant or seagrass from its origin in the Northwest Pacific, based on nuclear and chloroplast genomes. We identified two divergent Pacific clades with evidence for admixture along the East Pacific coast. Two west-to-east (trans-Pacific) colonization events support the key role of the North Pacific Current. Time-calibrated nuclear and chloroplast phylogenies yielded concordant estimates of the arrival of Z. marina in the Atlantic through the Canadian Arctic, suggesting that eelgrass-based ecosystems, hotspots of biodiversity and carbon sequestration, have only been present there for ~243 ky (thousand years). Mediterranean populations were founded ~44 kya, while extant distributions along western and eastern Atlantic shores were founded at the end of the Last Glacial Maximum (~19 kya), with at least one major refuge being the North Carolina region. The recent colonization and five- to sevenfold lower genomic diversity of the Atlantic compared to the Pacific populations raises concern and opportunity about how Atlantic eelgrass might respond to rapidly warming coastal oceans.

Functional trait trade-offs define plant population stability across different biomes.

Ecological theory posits that temporal stability patterns in plant populations are associated with differences in species' ecological strategies. However, empirical evidence is lacking about which traits, or trade-offs, underlie species stability, especially across different biomes. We compiled a worldwide collection of long-term permanent vegetation records (greater than 7000 plots from 78 datasets) from a large range of habitats which we combined with existing trait databases. We tested whether the observed inter-annual variability in species abundance (coefficient of variation) was related to multiple individual traits. We found that populations with greater leaf dry matter content and seed mass were more stable over time. Despite the variability explained by these traits being low, their effect was consistent across different datasets. Other traits played a significant, albeit weaker, role in species stability, and the inclusion of multi-variate axes or phylogeny did not substantially modify nor improve predictions. These results provide empirical evidence and highlight the relevance of specific ecological trade-offs, i.e. in different resource-use and dispersal strategies, for plant populations stability across multiple biomes. Further research is, however, necessary to integrate and evaluate the role of other specific traits, often not available in databases, and intraspecific trait variability in modulating species stability.

Long-term subtropical grassland plots take a long time to change: Replacement is more important than richness differences for beta diversity.

We studied ß diversity of grasses in a subtropical grassland over 60 years in South Africa. We examined the effects of burning and mowing on 132 large plots. We sought to determine the effects of burning and mowing, and mowing frequency, on the replacement of species and the species richness. We conducted the study at Ukulinga, research farm of the University of KwaZulu-Natal, Pietermaritzburg, South Africa (29°24'E, 30°24'S) from 1950-2010. Plots were burned annually, biennially, triennially, and a control (unburned). Plots were mowed in spring, late summer, spring plus late summer, and a control (unmowed). We calculated ß diversity, with a focus on replacement and richness differences. We also used distance-based redundancy analyses to examine the relative effects of replacement and richness differences on mowing and burning. We used beta regressions to test for the effect of soil depth and its interactions with mowing and burning. There was no significant change in grass beta diversity until 1995. Thereafter, there were changes in ß diversity that demonstrated the primary effects of summer mowing frequency. There was no significant effect of richness differences but a strong effect of replacement post-1995. There was a significant interaction between mowing frequency and soil depth in one of the analyses. Changes in grassland composition took a long time to manifest themselves and were unapparent prior to 1988. However, there was a change in sampling strategy prior to 1988, from point hits to nearest plants, that may also have influenced the rates of changes in replacement and richness differences. Using ß-diversity indices, we found that mowing was more important than burning that burning frequency was unimportant, and there was a significant interaction effect between mowing and soil depth in one of the analyses.

The Vitamin D Metabolite Ratio (VMR) is a Biomarker of Vitamin D Status That is Not Affected by Acute Changes in Vitamin D Binding Protein.

BACKGROUND: 25-hydroxyvitamin D[25(OH)D] may be a poor marker of vitamin D status due to variability in levels of vitamin D binding protein (VDBP). The vitamin D metabolite ratio (VMR) is the ratio of 24,25-dihydroxyvitamin D[24,25(OH)2D3] to 25(OH)D3 and has been postulated to reflect vitamin D sufficiency independent of variability in VDBP. Therapeutic plasma exchange (TPE) is a procedure that removes plasma, including VDBP, and may lower bound vitamin D metabolite concentrations. Effects of TPE on the VMR are unknown. METHODS: We measured 25(OH)D, free 25(OH)D, 1,25-dihydroxyvitamin D[1,25(OH)2D], 24,25(OH)2D3, and VDBP in persons undergoing TPE, before and after treatment. We used paired t-tests to assess changes in these biomarkers during a TPE procedure. RESULTS: Study participants (n = 45) had a mean age of 55 ± 16 years; 67% were female; and 76% were white. Compared to pretreatment concentrations, TPE caused a significant decrease in total VDBP by 65% (95%CI 60,70%), as well as all the vitamin D metabolites-25(OH)D by 66% (60%,74%), free 25(OH)D by 31% (24%,39%), 24,25(OH)2D3 by 66% (55%,78%) and 1,25(OH)2D by 68% (60%,76%). In contrast, there was no significant change in the VMR before and after a single TPE treatment, with an observed mean 7% (-3%, 17%) change in VMR. CONCLUSIONS: Changes in VDBP concentration across TPE parallel changes in 25(OH)D, 1,25(OH)2D, and 24,25(OH)2D3, suggesting that concentrations of these metabolites reflect underlying VDBP concentrations. The VMR is stable across a TPE session despite a 65% reduction in VDBP. These findings suggest that the VMR is a marker of vitamin D status independent of VDBP levels.

DNA storage in thermoresponsive microcapsules for repeated random multiplexed data access.

DNA has emerged as an attractive medium for archival data storage due to its durability and high information density. Scalable parallel random access to information is a desirable property of any storage system. For DNA-based storage systems, however, this still needs to be robustly established. Here we report on a thermoconfined polymerase chain reaction, which enables multiplexed, repeated random access to compartmentalized DNA files. The strategy is based on localizing biotin-functionalized oligonucleotides inside thermoresponsive, semipermeable microcapsules. At low temperatures, microcapsules are permeable to enzymes, primers and amplified products, whereas at high temperatures, membrane collapse prevents molecular crosstalk during amplification. Our data show that the platform outperforms non-compartmentalized DNA storage compared with repeated random access and reduces amplification bias tenfold during multiplex polymerase chain reaction. Using fluorescent sorting, we also demonstrate sample pooling and data retrieval by microcapsule barcoding. Therefore, the thermoresponsive microcapsule technology offers a scalable, sequence-agnostic approach for repeated random access to archival DNA files.