88 research outputs found

    GPS scintillations associated with cusp dynamics and polar cap patches

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    This paper investigates the relative scintillation level associated with cusp dynamics (including precipitation, flow shears, etc.) with and without the formation of polar cap patches around the cusp inflow region by the EISCAT Svalbard radar (ESR) and two GPS scintillation receivers. A series of polar cap patches were observed by the ESR between 8:40 and 10:20 UT on December 3, 2011. The polar cap patches combined with the auroral dynamics were associated with a significantly higher GPS phase scintillation level (up to 0.6 rad) than those observed for the other two alternatives, i.e., cusp dynamics without polar cap patches, and polar cap patches without cusp aurora. The cusp auroral dynamics without plasma patches were indeed related to GPS phase scintillations at a moderate level (up to 0.3 rad). The polar cap patches away from the active cusp were associated with sporadic and moderate GPS phase scintillations (up to 0.2 rad). The main conclusion is that the worst global navigation satellite system space weather events on the dayside occur when polar cap patches enter the polar cap and are subject to particle precipitation and flow shears, which is analogous to the nightside when polar cap patches exit the polar cap and enter the auroral oval

    Renal tubular function in children and adolescents with Gitelnian's syndrome, the hypocalciuric variant of Bartter's syndrome

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    Renal tubular function was studied in 14 patients with Gitelman's syndrome and 14 control subjects. Apart from the biochemical hallmarks of Gitelman's syndrome, namely alkalaemia, hyperbi carbonataemia, hypokalaemia, hypomagnesaemia (with increased magnesium over creatinine ratio), increased urinary chloride over creatinine ratio, and low urinary calcium over creatinine, the patients were found to have hyperproteinaemia, hypochloraemia, high total plasma calcium concentration, reduced plasma ionized calcium concentration, and high urinary sodium excretion. A statistically significant negative linear relationship between plasma magnesium concentration and magnesium excretion corrected for glomerular filtration was observed in patients. The fractional calcium clearance and the urinary excretion of calcium corrected for glomerular filtration was significantly decreased in patients. In patients the urin ary osmolality after overnight water deprivation ranged from 526 to 1067 mmol/kg. Glucosuria and aminoacid uria were similar in patients and controls. The results of the study demonstrate the renal origin of hypomag nesaemia and hypocalciuria in Gitelman's syndrome. The failure to demonstrate hyperaminoaciduria, hyperglucosuria, hyperphosphaturia, hyperuricosuria, and severely impaired urinary concentrating ability provide evidence for a defect residing in the distal convoluted tubul

    A comprehensive analysis of Helicobacter pylori plasticity zones reveals that they are integrating conjugative elements with intermediate integration specificity

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    Background: The human gastric pathogen Helicobacter pylori is a paradigm for chronic bacterial infections. Its persistence in the stomach mucosa is facilitated by several mechanisms of immune evasion and immune modulation, but also by an unusual genetic variability which might account for the capability to adapt to changing environmental conditions during long-term colonization. This variability is reflected by the fact that almost each infected individual is colonized by a genetically unique strain. Strain-specific genes are dispersed throughout the genome, but clusters of genes organized as genomic islands may also collectively be present or absent. Results: We have comparatively analysed such clusters, which are commonly termed plasticity zones, in a high number of H. pylori strains of varying geographical origin. We show that these regions contain fixed gene sets, rather than being true regions of genome plasticity, but two different types and several subtypes with partly diverging gene content can be distinguished. Their genetic diversity is incongruent with variations in the rest of the genome, suggesting that they are subject to horizontal gene transfer within H. pylori populations. We identified 40 distinct integration sites in 45 genome sequences, with a conserved heptanucleotide motif that seems to be the minimal requirement for integration. Conclusions: The significant number of possible integration sites, together with the requirement for a short conserved integration motif and the high level of gene conservation, indicates that these elements are best described as integrating conjugative elements (ICEs) with an intermediate integration site specificity

    The public health value of vaccines beyond efficacy: methods, measures and outcomes.

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    BACKGROUND: Assessments of vaccine efficacy and safety capture only the minimum information needed for regulatory approval, rather than the full public health value of vaccines. Vaccine efficacy provides a measure of proportionate disease reduction, is usually limited to etiologically confirmed disease, and focuses on the direct protection of the vaccinated individual. Herein, we propose a broader scope of methods, measures and outcomes to evaluate the effectiveness and public health impact to be considered for evidence-informed policymaking in both pre- and post-licensure stages. DISCUSSION: Pre-licensure: Regulatory concerns dictate an individually randomised clinical trial. However, some circumstances (such as the West African Ebola epidemic) may require novel designs that could be considered valid for licensure by regulatory agencies. In addition, protocol-defined analytic plans for these studies should include clinical as well as etiologically confirmed endpoints (e.g. all cause hospitalisations, pneumonias, acute gastroenteritis and others as appropriate to the vaccine target), and should include vaccine-preventable disease incidence and 'number needed to vaccinate' as outcomes. Post-licensure: There is a central role for phase IV cluster randomised clinical trials that allows for estimation of population-level vaccine impact, including indirect, total and overall effects. Dynamic models should be prioritised over static models as the constant force of infection assumed in static models will usually underestimate the effectiveness and cost-effectiveness of the immunisation programme by underestimating indirect effects. The economic impact of vaccinations should incorporate health and non-health benefits of vaccination in both the vaccinated and unvaccinated populations, thus allowing for estimation of the net social value of vaccination. CONCLUSIONS: The full benefits of vaccination reach beyond direct prevention of etiologically confirmed disease and often extend across the life course of a vaccinated person, prevent outcomes in the wider community, stabilise health systems, promote health equity, and benefit local and national economies. The degree to which vaccinations provide broad public health benefits is stronger than for other preventive and curative interventions

    Dayside Field-Aligned Current Impacts on Ionospheric Irregularities

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    Global Navigation Satellite Systems (GNSS) are subject to disturbances caused by plasma irregularities in the ionosphere. Studies have suggested that in addition to the gradient drift and Kelvin‐Helmholtz instabilities, electron precipitation may be important for phase scintillations in the dayside auroral region. This study combines in situ Swarm data with ground GNSS observations to investigate the potential role of filamentary field‐aligned currents (FACs) on phase scintillations in the dayside auroral region by analyzing 22 events with phase scintillations exceeding 0.45 radians. We observe colocation between regions of severe phase scintillations and highly filamented FACs with fluctuations measured in the spacecraft frame of the order of 20 Hz. The observations indicate that filamentary FACs are crucial drivers for irregularities responsible for creating severe phase scintillations measured in the dayside auroral region and are thus of significant importance in the context of space weather impact on satellite communication.publishedVersio

    Sensitivity to habitat fragmentation across European landscapes in three temperate forest herbs

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    Context Evidence for effects of habitat loss and fragmentation on the viability of temperate forest herb populations in agricultural landscapes is so far based on population genetic studies of single species in single landscapes. However, forest herbs differ in their life histories, and landscapes have different environments, structures and histories, making generalizations difficult. Objectives We compare the response of three slow-colonizing forest herbs to habitat loss and fragmentation and set this in relation to differences in life-history traits, in particular their mating system and associated pollinators. Methods We analysed the herbs' landscape-scale population genetic structure based on microsatellite markers from replicate forest fragments across seven European agricultural landscapes. Results All species responded to reductions in population size with a decrease in allelic richness and an increase in genetic differentiation among populations. Genetic differentiation also increased with enhanced spatial isolation. In addition, each species showed unique responses. Heterozygosity in the self-compatible Oxalis acetosella was reduced in smaller populations. The genetic diversity of Anemone nemorosa, whose main pollinators are less mobile, decreased with increasing spatial isolation, but not that of the bumblebee-pollinated Polygonatum multiflorum. Conclusions Our study indicates that habitat loss and fragmentation compromise the long-term viability of slow-colonizing forest herbs despite their ability to persist for many decades by clonal propagation. The distinct responses of the three species studied within the same landscapes confirm the need of multi-species approaches. The mobility of associated pollinators should be considered an important determinant of forest herbs' sensitivity to habitat loss and fragmentation

    Long Conserved Fragments Upstream of Mammalian Polyadenylation Sites

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    Polyadenylation is a cotranscriptional nuclear RNA processing event involving endonucleolytic cleavage of the nascent, emerging pre-messenger RNA (pre-mRNA) from the RNA polymerase, immediately followed by the polymerization of adenine ribonucleotides, called the poly(A) tail, to the cleaved 3′ end of the polyadenylation site (PAS). This apparently simple molecular processing step has been discovered to be connected to transcription and splicing therefore increasing its potential for regulation of gene expression. Here, through a bioinformatic analysis of cis-PAS–regulatory elements in mammals that includes taking advantage of multiple evolutionary time scales, we find unexpected selection pressure much further upstream, up to 200 nt, from the PAS than previously thought. Strikingly, close to 3,000 long (30–500 nt) noncoding conserved fragments (CFs) were discovered in the PAS flanking region of three remotely related mammalian species, human, mouse, and cow. When an even more remote transitional mammal, platypus, was included, still over a thousand CFs were found in the proximity of the PAS. Even though the biological function of these CFs remains unknown, their considerable sizes makes them unlikely to serve as protein recognition sites, which are typically ≤15 nt. By harnessing genome wide DNaseI hypersensitivity data, we have discovered that the presence of CFs correlates with chromatin accessibility. Our study is important in highlighting novel experimental targets, which may provide new understanding about the regulatory aspects of polyadenylation

    Global maps of soil temperature

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    Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0\u20135 and 5\u201315 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10\ub0C (mean = 3.0 \ub1 2.1\ub0C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 \ub1 2.3\ub0C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler ( 120.7 \ub1 2.3\ub0C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

    Global maps of soil temperature.

    Get PDF
    Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km <sup>2</sup> resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km <sup>2</sup> pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications
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