137 research outputs found

    The variable radio-to-X-ray spectrum of the magnetar XTE J1810-197

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    We have observed the 5.54s anomalous X-ray pulsar XTE J1810-197 at radio, millimeter, and infrared (IR) wavelengths, with the aim of learning about its broad-band spectrum. At the IRAM 30m telescope, we have detected the magnetar at 88 and 144GHz, the highest radio-frequency emission ever seen from a pulsar. At 88GHz we detected numerous individual pulses, with typical widths ~2ms and peak flux densities up to 45Jy. Together with nearly contemporaneous observations with the Parkes, Nancay, and Green Bank telescopes, we find that in late 2006 July the spectral index of the pulsar was -0.5<alpha<0 over the range 1.4-144GHz. Nine dual-frequency Very Large Array and Australia Telescope Compact Array observations in 2006 May-September are consistent with this finding, while showing variability of alpha with time. We infer from the IRAM observations that XTE J1810-197 remains highly linearly polarized at millimeter wavelengths. Also, toward this pulsar, the transition frequency between strong and weak scattering in the interstellar medium may be near 50GHz. At Gemini, we detected the pulsar at 2.2um in 2006 September, at the faintest level yet observed, K_s=21.89+-0.15. We have also analyzed four archival IR Very Large Telescope observations (two unpublished), finding that the brightness fluctuated within a factor of 2-3 over a span of 3 years, unlike the monotonic decay of the X-ray flux. Thus, there is no correlation between IR and X-ray flux, and it remains uncertain whether there is any correlation between IR and radio flux.Comment: Accepted for publication in ApJ; contains improved discussion of infrared uncertaintie

    Results from the Super Cryogenic Dark Matter Search (SuperCDMS) experiment at Soudan

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    We report the result of a blinded search for Weakly Interacting Massive Particles (WIMPs) using the majority of the SuperCDMS Soudan dataset. With an exposure of 1690 kg days, a single candidate event is observed, consistent with expected backgrounds. This analysis (combined with previous Ge results) sets an upper limit on the spin-independent WIMP--nucleon cross section of 1.4×10−441.4 \times 10^{-44} (1.0×10−441.0 \times 10^{-44}) cm2^2 at 46 GeV/c2c^2. These results set the strongest limits for WIMP--germanium-nucleus interactions for masses >>12 GeV/c2c^2

    The impact of hypoxia on B cells in COVID-19

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    Background: Prominent early features of COVID-19 include severe, often clinically silent, hypoxia and a pronounced reduction in B cells, the latter important in defence against SARS-CoV-2. This presentation resembles the phenotype of mice with VHL-deficient B cells, in which Hypoxia-Inducible Factors are constitutively active, suggesting hypoxia might drive B cell abnormalities in COVID-19. Methods: Detailed B cell phenotyping was undertaken by flow-cytometry on longitudinal samples from patients with COVID-19 across a range of severities (NIHR Cambridge BioResource). The impact of hypoxia on the transcriptome was assessed by single-cell and whole blood RNA sequencing analysis. The direct effect of hypoxia on B cells was determined through immunisation studies in genetically modified and hypoxia-exposed mice. Findings: We demonstrate the breadth of early and persistent defects in B cell subsets in moderate/severe COVID-19, including reduced marginal zone-like, memory and transitional B cells, changes also observed in B cell VHL-deficient mice. These findings were associated with hypoxia-related transcriptional changes in COVID-19 patient B cells, and similar B cell abnormalities were seen in mice kept in hypoxic conditions. Interpretation: Hypoxia may contribute to the pronounced and persistent B cell pathology observed in acute COVID-19 pneumonia. Assessment of the impact of early oxygen therapy on these immune defects should be considered, as their correction could contribute to improved outcomes. Funding: Evelyn Trust, Addenbrooke's Charitable Trust, UKRI/NIHR, Wellcome Trus

    Ticks parasitised feathered dinosaurs as revealed by Cretaceous amber assemblages

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    Ticks are currently among the most prevalent blood-feeding ectoparasites, but their feeding habits and hosts in deep time have long remained speculative. Here, we report direct and indirect evidence in 99 million-year-old Cretaceous amber showing that hard ticks and ticks of the extinct new family Deinocrotonidae fed on blood from feathered dinosaurs, non-avialan or avialan excluding crown-group birds. A dagger Cornupalpatum burmanicum hard tick is entangled in a pennaceous feather. Two deinocrotonids described as dagger Deinocroton draculi gen. et sp. nov. have specialised setae from dermestid beetle larvae (hastisetae) attached to their bodies, likely indicating cohabitation in a feathered dinosaur nest. A third conspecific specimen is blood-engorged, its anatomical features suggesting that deinocrotonids fed rapidly to engorgement and had multiple gonotrophic cycles. These findings provide insight into early tick evolution and ecology, and shed light on poorly known arthropod-vertebrate interactions and potential disease transmission during the Mesozoic

    Ticks parasitised feathered dinosaurs as revealed by Cretaceous amber assemblages

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    Ticks are currently among the most prevalent blood-feeding ectoparasites, but their feeding habits and hosts in deep time have long remained speculative. Here, we report direct and indirect evidence in 99 million-year-old Cretaceous amber showing that hard ticks and ticks of the extinct new family Deinocrotonidae fed on blood from feathered dinosaurs, non-avialan or avialan excluding crown-group birds. A dagger Cornupalpatum burmanicum hard tick is entangled in a pennaceous feather. Two deinocrotonids described as dagger Deinocroton draculi gen. et sp. nov. have specialised setae from dermestid beetle larvae (hastisetae) attached to their bodies, likely indicating cohabitation in a feathered dinosaur nest. A third conspecific specimen is blood-engorged, its anatomical features suggesting that deinocrotonids fed rapidly to engorgement and had multiple gonotrophic cycles. These findings provide insight into early tick evolution and ecology, and shed light on poorly known arthropod-vertebrate interactions and potential disease transmission during the Mesozoic

    Risks of Ventricular Arrhythmia and Heart Failure in Carriers of RBM20 Variants

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    BACKGROUND: Variants in RBM20 are reported in 2% to 6% of familial cases of dilated cardiomyopathy and may be associated with fatal ventricular arrhythmia and rapid heart failure progression. We sought to determine the risk of adverse events in RBM20 variant carriers and the impact of sex on outcomes. METHODS: Consecutive probands and relatives carrying RBM20 variants were retrospectively recruited from 12 cardiomyopathy units. The primary end point was a composite of malignant ventricular arrhythmia (MVA) and end-stage heart failure (ESHF). MVA and ESHF end points were also analyzed separately and males and females compared. Left ventricular ejection fraction (LVEF) contemporary to MVA was examined. RBM20 variant carriers with left ventricular systolic dysfunction (RBM20LVSD) were compared with variant-elusive patients with idiopathic left ventricular systolic dysfunction. RESULTS: Longitudinal follow-up data were available for 143 RBM20 variant carriers (71 male; median age, 35.5 years); 7 of 143 had an MVA event at baseline. Thirty of 136 without baseline MVA (22.0%) reached the primary end point, and 16 of 136 (11.8%) had new MVA with no significant difference between males and females (log-rank P=0.07 and P=0.98, respectively). Twenty of 143 (14.0%) developed ESHF (17 males and 3 females; log-rank P35%. At 5 years, 15 of 67 (22.4%) RBM20LVSD versus 7 of 197 (3.6%) patients with idiopathic left ventricular systolic dysfunction had reached the primary end point (log-rank P<0.001). RBM20 variant carriage conferred a 6.0-fold increase in risk of the primary end point. CONCLUSIONS: RBM20 variants are associated with a high risk of MVA and ESHF compared with idiopathic left ventricular systolic dysfunction. The risk of MVA in male and female RBM20 variant carriers is similar, but male sex is strongly associated with ESHF

    Lutzomyia adiketis sp. n. (Diptera: Phlebotomidae), a vector of Paleoleishmania neotropicum sp. n. (Kinetoplastida: Trypanosomatidae) in Dominican amber

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    <p>Abstract</p> <p>Background</p> <p>Amber fossils can be used to trace the history of disease-vector associations because microorganisms are preserved "in situ" inside the alimentary tract and body cavity of blood-sucking insects.</p> <p>Results</p> <p><it>Lutzomyia adiketis </it>sp. n. (Phlebotomidae: Diptera) is described from Dominican amber as a vector of <it>Paleoleishmania neotropicum </it>sp. n. (Kinetoplastida: Trypanosomatidae). The fossil sand fly differs from all previously described extinct and extant members of the genus by the following combination of characters: Sc forked with the branches meeting the costa and radius veins; wing L/W value of 4.1; a δ value of 18; a ratio β/α value of 0.86, and the shape and size of the spatulate rods on the ninth sternite. The trypanosomatid is characterized by the structure of its promastigotes, amastigotes and paramastigotes and its transmission by an extinct species of sand fly.</p> <p>Conclusion</p> <p>Morphological characters show that the fossil sand fly is a new extinct species and that it is host to a digenetic species of trypanosomatid. This study provides the first fossil evidence that Neotropical sand flies were vectors of trypanosomatids in the mid-Tertiary (20–30 mya).</p

    Public, private and personal: Qualitative research on policymakers' opinions on smokefree interventions to protect children in 'private' spaces

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    <p>Abstract</p> <p>Background</p> <p>Governments use law to constrain aspects of private activities for purposes of protecting health and social wellbeing. Policymakers have a range of perceptions and beliefs about what is public or private. An understanding of the possible drivers of policymaker decisions about where government can or should intervene for health is important, as one way to better guide appropriate policy formation. Our aim was to identify obstacles to, and opportunities for, government smokefree regulation of private and public spaces to protect children. In particular, to seek policymaker opinions on the regulation of smoking in homes, cars and public parks and playgrounds in a country with incomplete smokefree laws (New Zealand).</p> <p>Methods</p> <p>Case study, using structured interviews to ask policymakers (62 politicians and senior officials) about their opinions on new smokefree legislation for public and private places. Supplementary data was obtained from the Factiva media database, on the views of New Zealand local authority councillors about policies for smokefree outdoor public places.</p> <p>Results</p> <p>Overall, interviewees thought that government regulation of smoking in private places was impractical and unwise. However, there were some differences on what <it>was </it>defined as 'private', particularly for cars. Even in public parks, smoking was seen by some as a 'personal' decision, and unlikely to be amenable to regulation. Most participants believed that educative, supportive and community-based measures were better and more practical means of reducing smoking in private places, compared to regulation.</p> <p>Conclusions</p> <p>The constrained view of the role of regulation of smoking in public and private domains may be in keeping with current political discourse in New Zealand and similar Anglo-American countries. Policy and advocacy options to promote additional smokefree measures include providing a better voice for childrens' views, increasing information to policymakers about the harms to children from secondhand smoke and the example of adult smoking, and changing the culture for smoking around children.</p

    The potential utility of B cell-directed biologic therapy in autoimmune diseases

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    Increasing awareness of the importance of aberrant B cell regulation in autoimmunity has driven the clinical development of novel B cell-directed biologic therapies with the potential to treat a range of autoimmune disorders. The first of these drugs—rituximab, a chimeric monoclonal antibody against the B cell-specific surface marker CD20—was recently approved for treating rheumatoid arthritis in patients with an inadequate response to other biologic therapies. The aim of this review is to discuss the potential use of rituximab in the management of other autoimmune disorders. Results from early phase clinical trials indicate that rituximab may provide clinical benefit in systemic lupus erythematosus, Sjögren’s syndrome, vasculitis, and thrombocytopenic purpura. Numerous case reports and several small pilot studies have also been published reporting the use of rituximab in conditions such as myositis, antiphospholipid syndrome, Still’s disease, and multiple sclerosis. In general, the results from these preliminary studies encourage further testing of rituximab therapy in formalized clinical trials. Based on results published to date, it is concluded that rituximab, together with other B cell-directed therapies currently under clinical development, is likely to provide an important new treatment option for a number of these difficult-to-treat autoimmune disorders
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