201 research outputs found

    Planet Eclipse Mapping with Long-Term Baseline Drifts

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    High precision lightcurves combined with eclipse mapping techniques can reveal the horizontal and vertical structure of a planet's thermal emission and the dynamics of hot Jupiters. Someday, they even may reveal the surface maps of rocky planets. However, inverting lightcurves into maps requires an understanding of the planet, star and instrumental trends because they can resemble the gradual flux variations as the planet rotates (ie. partial phase curves). In this work, we simulate lightcurves with baseline trends and assess the impact on planet maps. Baseline trends can be erroneously modeled by incorrect astrophysical planet map features, but there are clues to avoid this pitfall in both the residuals of the lightcurve during eclipse and sharp features at the terminator of the planet. Models that use a Gaussian process or polynomial to account for a baseline trend successfully recover the input map even in the presence of systematics but with worse precision for the m=1 spherical harmonic terms. This is also confirmed with the ThERESA eigencurve method where fewer lightcurve terms can model the planet without correlations between the components. These conclusions help aid the decision on how to schedule observations to improve map precision. If the m=1 components are critical, such as measuring the East/West hotspot shift on a hot Jupiter, better characterization of baseline trends can improve the m=1 terms' precision. For latitudinal North/South information from the remaining mapping terms, it is preferable to obtain high signal-to-noise at ingress/egress with more eclipses.Comment: AJ, accepted, 22 page

    Mechanisms of hypertension during and after orthotopic liver transplantation in children

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    The aim of this study was to assess the hormonal alterations that may mediate the systemic hypertension that develops in patients during the perioperative period of orthotopic liver transplantation. We studied nine pediatric patients without previous hypertension or renal disease during six time points, starting before transplantation and ending at 48 hours after surgery. Hypertension developed in all patients in association with central venous pressures <10 mm Hg. Free water clearance was negative in all nine patients. Vasopressin levels increased intraoperatively but fell as hypertension developed. Atrial natriuretic factor levels increased as systemic blood pressure rose. A high level of plasma renin activity was observed in four patients with renal insufficiency. In six patients, postoperative 24-hour urinary norepinephrine excretion was within the normal age-adjusted range. These findings suggest that the combination of cyclosporine, corticosteroids, and, in some patients, an elevated plasma renin activity prevents the kidney from responding to the acute volume and salt overload with an appropriate diuresis and natriuresis, thus leading to systemic hypertension. The treatment of hypertension after liver transplantation may include salt restriction, diuretics, and, in those patients with a low creatinine excretion index, anglotensin coverting enzyme inhibitors. © 1989 The C. V. Mosby Company

    Home telemonitoring and remote feedback between clinic visits for asthma.

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    BACKGROUND: Asthma is a chronic disease that causes reversible narrowing of the airways due to bronchoconstriction, inflammation and mucus production. Asthma continues to be associated with significant avoidable morbidity and mortality. Self management facilitated by a healthcare professional is important to keep symptoms controlled and to prevent exacerbations.Telephone and Internet technologies can now be used by patients to measure lung function and asthma symptoms at home. Patients can then share this information electronically with their healthcare provider, who can provide feedback between clinic visits. Technology can be used in this manner to improve health outcomes and prevent the need for emergency treatment for people with asthma and other long-term health conditions. OBJECTIVES: To assess the efficacy and safety of home telemonitoring with healthcare professional feedback between clinic visits, compared with usual care. SEARCH METHODS: We identified trials from the Cochrane Airways Review Group Specialised Register (CAGR) up to May 2016. We also searched www.clinicaltrials.gov, the World Health Organization (WHO) trials portal and reference lists of other reviews, and we contacted trial authors to ask for additional information. SELECTION CRITERIA: We included parallel randomised controlled trials (RCTs) of adults or children with asthma in which any form of technology was used to measure and share asthma monitoring data with a healthcare provider between clinic visits, compared with other monitoring or usual care. We excluded trials in which technologies were used for monitoring with no input from a doctor or nurse. We included studies reported as full-text articles, those published as abstracts only and unpublished data. DATA COLLECTION AND ANALYSIS: Two review authors screened the search and independently extracted risk of bias and numerical data, resolving disagreements by consensus.We analysed dichotomous data as odds ratios (ORs) while using study participants as the unit of analysis, and continuous data as mean differences (MDs) while using random-effects models. We rated evidence for all outcomes using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation Working Group) approach. MAIN RESULTS: We found 18 studies including 2268 participants: 12 in adults, 5 in children and one in individuals from both age groups. Studies generally recruited people with mild to moderate persistent asthma and followed them for between three and 12 months. People in the intervention group were given one of a variety of technologies to record and share their symptoms (text messaging, Web systems or phone calls), compared with a group of people who received usual care or a control intervention.Evidence from these studies did not show clearly whether asthma telemonitoring with feedback from a healthcare professional increases or decreases the odds of exacerbations that require a course of oral steroids (OR 0.93, 95% confidence Interval (CI) 0.60 to 1.44; 466 participants; four studies), a visit to the emergency department (OR 0.75, 95% CI 0.36 to 1.58; 1018 participants; eight studies) or a stay in hospital (OR 0.56, 95% CI 0.21 to 1.49; 1042 participants; 10 studies) compared with usual care. Our confidence was limited by imprecision in all three primary outcomes. Evidence quality ratings ranged from moderate to very low. None of the studies recorded serious or non-serious adverse events separately from asthma exacerbations.Evidence for measures of asthma control was imprecise and inconsistent, revealing possible benefit over usual care for quality of life (MD 0.23, 95% CI 0.01 to 0.45; 796 participants; six studies; I(2) = 54%), but the effect was small and study results varied. Telemonitoring interventions may provide additional benefit for two measures of lung function. AUTHORS' CONCLUSIONS: Current evidence does not support the widespread implementation of telemonitoring with healthcare provider feedback between asthma clinic visits. Studies have not yet proven that additional telemonitoring strategies lead to better symptom control or reduced need for oral steroids over usual asthma care, nor have they ruled out unintended harms. Investigators noted small benefits for quality of life, but these are subject to risk of bias, as the studies were unblinded. Similarly, some benefits for lung function are uncertain owing to possible attrition bias.Larger pragmatic studies in children and adults could better determine the real-world benefits of these interventions for preventing exacerbations and avoiding harms; it is difficult to generalise results from this review because benefits may be explained at least in part by the increased attention participants receive by taking part in clinical trials. Qualitative studies could inform future research by focusing on patient and provider preferences, or by identifying subgroups of patients who are more likely to attain benefit from closer monitoring, such as those who have frequent asthma attacks

    Remote versus face-to-face check-ups for asthma.

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    BACKGROUND: Asthma remains a significant cause of avoidable morbidity and mortality. Regular check-ups with a healthcare professional are essential to monitor symptoms and adjust medication.Health services worldwide are considering telephone and internet technologies as a way to manage the rising number of people with asthma and other long-term health conditions. This may serve to improve health and reduce the burden on emergency and inpatient services. Remote check-ups may represent an unobtrusive and efficient way of maintaining contact with patients, but it is uncertain whether conducting check-ups in this way is effective or whether it may have unexpected negative consequences. OBJECTIVES: To assess the safety and efficacy of conducting asthma check-ups remotely versus usual face-to-face consultations. SEARCH METHODS: We identified trials from the Cochrane Airways Review Group Specialised Register (CAGR) up to 24 November 2015. We also searched www.clinicaltrials.gov, the World Health Organization (WHO) trials portal, reference lists of other reviews and contacted trial authors for additional information. SELECTION CRITERIA: We included parallel randomised controlled trials (RCTs) of adults or children with asthma that compared remote check-ups conducted using any form of technology versus standard face-to-face consultations. We excluded studies that used automated telehealth interventions that did not include personalised contact with a health professional. We included studies reported as full-text articles, as abstracts only and unpublished data. DATA COLLECTION AND ANALYSIS: Two review authors screened the literature search results and independently extracted risk of bias and numerical data. We resolved any disagreements by consensus, and we contacted study authors for missing information.We analysed dichotomous data as odds ratios (ORs) using study participants as the unit of analysis, and continuous data as mean differences using the random-effects models. We rated all outcomes using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. MAIN RESULTS: Six studies including a total of 2100 participants met the inclusion criteria: we pooled four studies including 792 people in the main efficacy analyses, and presented the results of a cluster implementation study (n = 1213) and an oral steroid tapering study (n = 95) separately. Baseline characteristics relating to asthma severity were variable, but studies generally recruited people with asthma taking regular medications and excluded those with COPD or severe asthma. One study compared the two types of check-up for oral steroid tapering in severe refractory asthma and we assessed it as a separate question. The studies could not be blinded and dropout was high in four of the six studies, which may have biased the results.We could not say whether more people who had a remote check-up needed oral corticosteroids for an asthma exacerbation than those who were seen face-to-face because the confidence intervals (CIs) were very wide (OR 1.74, 95% CI 0.41 to 7.44; 278 participants; one study; low quality evidence). In the face-to-face check-up groups, 21 participants out of 1000 had exacerbations that required oral steroids over three months, compared to 36 (95% CI nine to 139) out of 1000 for the remote check-up group. Exacerbations that needed treatment in the Emergency Department (ED), hospital admission or an unscheduled healthcare visit all happened too infrequently to detect whether remote check-ups are a safe alternative to face-to-face consultations. Serious adverse events were not reported separately from the exacerbation outcomes.There was no difference in asthma control measured by the Asthma Control Questionnaire (ACQ) or in quality of life measured on the Asthma Quality of Life Questionnaire (AQLQ) between remote and face-to-face check-ups. We could rule out significant harm of remote check-ups for these outcomes but we were less confident because these outcomes are more prone to bias from lack of blinding.The larger implementation study that compared two general practice populations demonstrated that offering telephone check-ups and proactively phoning participants increased the number of people with asthma who received a review. However, we do not know whether the additional participants who had a telephone check-up subsequently benefited in asthma outcomes. AUTHORS' CONCLUSIONS: Current randomised evidence does not demonstrate any important differences between face-to-face and remote asthma check-ups in terms of exacerbations, asthma control or quality of life. There is insufficient information to rule out differences in efficacy, or to say whether or not remote asthma check-ups are a safe alternative to being seen face-to-face

    A roadmap to the efficient and robust characterization of temperate terrestrial planet atmospheres with JWST

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    Ultra-cool dwarf stars are abundant, long-lived, and uniquely suited to enable the atmospheric study of transiting terrestrial companions with JWST. Amongst them, the most prominent is the M8.5V star TRAPPIST-1 and its seven planets, which have been the favored targets of eight JWST Cycle 1 programs. While Cycle 1 observations have started to yield preliminary insights into the planets, they have also revealed that their atmospheric exploration requires a better understanding of their host star. Here, we propose a roadmap to characterize the TRAPPIST-1 system -- and others like it -- in an efficient and robust manner. We notably recommend that -- although more challenging to schedule -- multi-transit windows be prioritized to constrain stellar heterogeneities and gather up to 2×\times more transits per JWST hour spent. We conclude that in such systems planets cannot be studied in isolation by small programs, thus large-scale community-supported programs should be supported to enable the efficient and robust exploration of terrestrial exoplanets in the JWST era

    Specific ion channels contribute to key elements of pathology during secondary degeneration following neurotrauma

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    Background: Following partial injury to the central nervous system, cells beyond the initial injury site undergo secondary degeneration, exacerbating loss of neurons, compact myelin and function. Changes in Ca 2+ flux are associated with metabolic and structural changes, but it is not yet clear how flux through specific ion channels contributes to the various pathologies. Here, partial optic nerve transection in adult female rats was used to model secondary degeneration. Treatment with combinations of three ion channel inhibitors was used as a tool to investigate which elements of oxidative and structural damage related to long term functional outcomes. The inhibitors employed were the voltage gated Ca 2+ channel inhibitor Lomerizine (Lom), the Ca 2+ permeable AMPA receptor inhibitor YM872 and the P2X 7 receptor inhibitor oxATP. Results: Following partial optic nerve transection, hyper-phosphorylation of Tau and acetylated tubulin immunoreactivity were increased, and Nogo-A immunoreactivity was decreased, indicating that axonal changes occurred acutely. All combinations of ion channel inhibitors reduced hyper-phosphorylation of Tau and increased Nogo-A immunoreactivity at day 3 after injury. However, only Lom/oxATP or all three inhibitors in combination significantly reduced acetylated tubulin immunoreactivity. Most combinations of ion channel inhibitors were effective in restoring the lengths of the paranode and the paranodal gap, indicative of the length of the node of Ranvier, following injury. However, only all three inhibitors in combination restored to normal Ankyrin G length at the node of Ranvier. Similarly, HNE immunoreactivity and loss of oligodendrocyte precursor cells were only limited by treatment with all three ion channel inhibitors in combination. Conclusions: Data indicate that inhibiting any of a range of ion channels preserves certain elements of axon and node structure and limits some oxidative damage following injury, whereas ionic flux through all three channels must be inhibited to prevent lipid peroxidation and preserve Ankyrin G distribution and OPCs

    Early Release Science of the exoplanet WASP-39b with JWST NIRCam

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    Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres is a fundamental step towards constraining the dominant chemical processes at work and, if in equilibrium, revealing planet formation histories. Transmission spectroscopy provides the necessary means by constraining the abundances of oxygen- and carbon-bearing species; however, this requires broad wavelength coverage, moderate spectral resolution, and high precision that, together, are not achievable with previous observatories. Now that JWST has commenced science operations, we are able to observe exoplanets at previously uncharted wavelengths and spectral resolutions. Here we report time-series observations of the transiting exoplanet WASP-39b using JWST's Near InfraRed Camera (NIRCam). The long-wavelength spectroscopic and short-wavelength photometric light curves span 2.0 - 4.0 μ\mum, exhibit minimal systematics, and reveal well-defined molecular absorption features in the planet's spectrum. Specifically, we detect gaseous H2_2O in the atmosphere and place an upper limit on the abundance of CH4_4. The otherwise prominent CO2_2 feature at 2.8 μ\mum is largely masked by H2_2O. The best-fit chemical equilibrium models favour an atmospheric metallicity of 1-100×\times solar (i.e., an enrichment of elements heavier than helium relative to the Sun) and a sub-stellar carbon-to-oxygen (C/O) ratio. The inferred high metallicity and low C/O ratio may indicate significant accretion of solid materials during planet formation or disequilibrium processes in the upper atmosphere.Comment: 35 pages, 13 figures, 3 tables, Nature, accepte

    Identification of carbon dioxide in an exoplanet atmosphere

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    Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (that is, elements heavier than helium, also called ‘metallicity’), and thus the formation processes of the primary atmospheres of hot gas giants. It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets. Previous photometric measurements of transiting planets with the Spitzer Space Telescope have given hints of the presence of CO2, but have not yielded definitive detections owing to the lack of unambiguous spectroscopic identification. Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science programme. The data used in this study span 3.0–5.5 micrometres in wavelength and show a prominent CO2 absorption feature at 4.3 micrometres (26-sigma significance). The overall spectrum is well matched by one-dimensional, ten-times solar metallicity models that assume radiative–convective–thermochemical equilibrium and have moderate cloud opacity. These models predict that the atmosphere should have water, carbon monoxide and hydrogen sulfide in addition to CO2, but little methane. Furthermore, we also tentatively detect a small absorption feature near 4.0 micrometres that is not reproduced by these models

    Molecular specification of germ layers in vertebrate embryos

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