54 research outputs found

    Interventions to Improve Delivery of Isoniazid Preventive Therapy: an Overview of Systematic Reviews

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    Background: Uptake of isoniazid preventive therapy (IPT) to prevent tuberculosis has been poor, particularly in the highest risk populations. Interventions to improve IPT delivery could promote implementation. The large number of existing systematic reviews on treatment adherence has made drawing conclusions a challenge. To provide decision makers with the evidence they need, we performed an overview of systematic reviews to compare different organizational interventions to improve IPT delivery as measured by treatment completion among those at highest risk for the development of TB disease, namely child contacts or HIV-infected individuals. Methods: We searched the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects (DARE), and MEDLINE up to August 15, 2012. Two authors used a standardized data extraction form and the AMSTAR instrument to independently assess each review. Results: Six reviews met inclusion criteria. Interventions included changes in the setting/site of IPT delivery, use of quality monitoring mechanisms (e.g., directly observed therapy), IPT delivery integration into other healthcare services, and use of lay health workers. Most reviews reported a combination of outcomes related to IPT adherence and treatment completion rate but without a baseline or comparison rate. Generally, we found limited evidence to demonstrate that the studied interventions improved treatment completion. Conclusions: While most of the interventions were not shown to improve IPT completion, integration of tuberculosis and HIV services yielded high treatment completion rates in some settings. The lack of data from high burden TB settings limits applicability. Further research to assess different IPT delivery interventions, including those that address barriers to care in at-risk populations, is urgently needed to identify the most effective practices for IPT delivery and TB control in high TB burden settings

    Obliquity Constraints on an Extrasolar Planetary-Mass Companion

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    We place the first constraints on the obliquity of a planetary-mass companion outside of the solar system. Our target is the directly imaged system 2MASS J01225093–2439505 (2M0122), which consists of a 120 Myr 0.4 M⊙ star hosting a 12–27 M_J companion at 50 au. We constrain all three of the system's angular-momentum vectors: how the companion spin axis, the stellar spin axis, and the orbit normal are inclined relative to our line of sight. To accomplish this, we measure projected rotation rates (v sin i) for both the star and the companion using new near-infrared high-resolution spectra with NIRSPEC at Keck Observatory. We combine these with a new stellar photometric rotation period from TESS and a published companion rotation period from Hubble Space Telescope to obtain spin-axis inclinations for both objects. We also fitted multiple epochs of astrometry, including a new observation with NIRC2/Keck, to measure 2M0122b's orbital inclination. The three line-of-sight inclinations place limits on the true de-projected companion obliquity and stellar obliquity. We find that while the stellar obliquity marginally prefers alignment, the companion obliquity tentatively favors misalignment. We evaluate possible origin scenarios. While collisions, secular spin–orbit resonances, and Kozai–Lidov oscillations are unlikely, formation by gravitational instability in a gravito-turbulent disk—the scenario favored for brown dwarf companions to stars—appears promising

    Face-to-Face Compared With Online Collected Accounts of Health and Illness Experiences: A Scoping Review.

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    Advocates of online alternatives to face-to-face interviewing suggest online approaches save money and time, whereas others have raised concerns about the quality and content of the resulting data. These issues affect researchers designing and costing their studies and application reviewers and research funders. We conducted a scoping review of English language articles describing the range of online alternative approaches. Furthermore, we systematically identified studies directly comparing online alternatives with face-to-face approaches. Synthesis of these 11 articles (565 participants) suggests that online alternatives should not be viewed as a straightforward replacement for face-to-face, a particularly important finding given the rapid communication changes occurring in the COVID-19 pandemic. When applied with consideration of the evolving evidence on their strengths and weaknesses, online methods may increase the likelihood of obtaining the desired sample, but responses are shorter, less contextual information is obtained, and relational satisfaction and consensus development are lower

    No difference in orbital parameters of RV-detected giant planets between 0.1 and 5 au in single vs multi-stellar systems

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    Our Keck/NIRC2 imaging survey searches for stellar companions around 144 systems with radial velocity (RV) detected giant planets to determine whether stellar binaries influence the planets' orbital parameters. This survey, the largest of its kind to date, finds eight confirmed binary systems and three confirmed triple systems. These include three new multi-stellar systems (HD 30856, HD 86081, and HD 207832) and three multi-stellar systems with newly confirmed common proper motion (HD 43691, HD 116029, and HD 164509). We combine these systems with seven RV planet-hosting multi-stellar systems from the literature in order to test for differences in the properties of planets with semimajor axes ranging between 0.1-5 au in single vs multi-stellar systems. We find no evidence that the presence or absence of stellar companions alters the distribution of planet properties in these systems. Although the observed stellar companions might influence the orbits of more distant planetary companions in these systems, our RV observations currently provide only weak constraints on the masses and orbital properties of planets beyond 5 au. In order to aid future efforts to characterize long period RV companions in these systems, we publish our contrast curves for all 144 targets. Using four years of astrometry for six hierarchical triple star systems hosting giant planets, we fit the orbits of the stellar companions in order to characterize the orbital architecture in these systems. We find that the orbital plane of the secondary and tertiary companions are inconsistent with an edge-on orbit in four out of six cases.Comment: 34 pages, 10 figures, 16 tables, including 4 tables in machine readable format and 7 tables with online supplemental dat

    Searching for Scatterers: High-Contrast Imaging of Young Stars Hosting Wide-Separation Planetary-Mass Companions

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    We have conducted an angular differential imaging survey with NIRC2 at Keck in search of close-in substellar companions to a sample of seven systems with confirmed planetary-mass companions (PMCs) on wide orbits (>50 au). These wide-separation PMCs pose significant challenges to all three possible formation mechanisms: core accretion plus scattering, disk instability, and turbulent fragmentation. We explore the possibility that these companions formed closer in and were scattered out to their present-day locations by searching for other massive bodies at smaller separations. The typical sensitivity for this survey is ΔK ~ 12.5 at 1". We identify eight candidate companions, whose masses would reach as low as one Jupiter mass if gravitationally bound. From our multi-epoch astrometry we determine that seven of these are conclusively background objects, while the eighth near DH Tau is ambiguous and requires additional monitoring. We rule out the presence of >7 M_(Jup) bodies in these systems down to 15–50 au that could be responsible for scattering. This result combined with the totality of evidence suggests that dynamical scattering is unlikely to have produced this population of PMCs. We detect orbital motion from the companions ROXs 42B b and ROXs 12 b, and from this determine 95% upper limits on the companions' eccentricities of 0.58 and 0.83 respectively. Finally, we find that the 95% upper limit on the occurrence rate of additional planets with masses between 5 and 15 M_(Jup) outside of 40 au in systems with PMCs is 54%

    Updated Parameters and a New Transmission Spectrum of HD 97658b

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    Recent years have seen increasing interest in the characterization of sub-Neptune-sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD 97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four Hubble Space Telescope transits, 12 Spitzer/IRAC transits, and eight MOST transits of this system. Our transmission spectrum has a higher signal-to-noise ratio than those from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1–1.7 μm reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are inconclusive, as no model provides an excellent match to our data. Nonetheless, we find that atmospheres with high C/O ratios (C/O ≳ 0.8) and metallicities of ≳100× solar metallicity are favored. We combine the mid-transit times from all of the new Spitzer and MOST observations and obtain an updated orbital period of P = 9.489295 ± 0.000005, with a best-fit transit time center at T₀ = 2456361.80690 ± 0.00038 (BJD). No transit timing variations are found in this system. We also present new measurements of the stellar rotation period (34 ± 2 days) and stellar activity cycle (9.6 yr) of the host star HD 97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000 K and with sizes between 1 R⊕ and 4 R⊕. We find that at least a third of small planets cooler than 1000 K can be well characterized using James Webb Space Telescope, and of those, HD 97658b is ranked fifth, meaning that it remains a high-priority target for atmospheric characterization

    Searching for Scatterers: High-Contrast Imaging of Young Stars Hosting Wide-Separation Planetary-Mass Companions

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    We have conducted an angular differential imaging survey with NIRC2 at Keck in search of close-in substellar companions to a sample of seven systems with confirmed planetary-mass companions (PMCs) on wide orbits (>50 au). These wide-separation PMCs pose significant challenges to all three possible formation mechanisms: core accretion plus scattering, disk instability, and turbulent fragmentation. We explore the possibility that these companions formed closer in and were scattered out to their present-day locations by searching for other massive bodies at smaller separations. The typical sensitivity for this survey is ΔK ~ 12.5 at 1". We identify eight candidate companions, whose masses would reach as low as one Jupiter mass if gravitationally bound. From our multi-epoch astrometry we determine that seven of these are conclusively background objects, while the eighth near DH Tau is ambiguous and requires additional monitoring. We rule out the presence of >7 M_(Jup) bodies in these systems down to 15–50 au that could be responsible for scattering. This result combined with the totality of evidence suggests that dynamical scattering is unlikely to have produced this population of PMCs. We detect orbital motion from the companions ROXs 42B b and ROXs 12 b, and from this determine 95% upper limits on the companions' eccentricities of 0.58 and 0.83 respectively. Finally, we find that the 95% upper limit on the occurrence rate of additional planets with masses between 5 and 15 M_(Jup) outside of 40 au in systems with PMCs is 54%

    Readmissions after general surgery: a prospective multicenter audit

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    Background: Readmission rates after surgical procedures are viewed as a marker of quality of care and as a driver to improve outcomes in the United Kingdom, they are not remunerated. However, readmissions are not wholly avoidable. The aim of this study was to develop a regional overview of readmissions to determine the proportion that might be avoidable and to examine predictors of readmissions at a unit level. Methods: We undertook a prospective multicenter audit of readmissions following National Health Service funded general surgical procedures in five National Health Service hospitals and three independent sector providers over a 2-wk period. Basic demographic and procedure data were captured. Readmissions to hospitals were identified through acute admissions lists. Reason for readmission was identified, and the readmission data assessed by a senior surgical doctor as to whether it was avoidable. Results: We identified 752 operations in the study period with all followed up to 30 d. The overall rate of readmissions was 4.7%, with 40% of these judged as being potentially avoidable. Pain and wound problems accounted for the vast majority of avoidable readmissions. The number of unavoidable readmissions was correlated with the workload of each center (r ÂĽ 0.63, P ÂĽ 0.06) and as with the higher (British United Provident Association) complexity of surgery (r ÂĽ 0.90, P ÂĽ 0.01). Patient and demographic factors were not associated with readmissions. Conclusions: This prospective audit describes readmission rates after general surgery. Volume and complexity of work are associated with readmission rates. A large proportion of readmissions could be reduced by attention to analgesia and outpatient arrangements for wound management

    Overfitting Affects the Reliability of Radial Velocity Mass Estimates of the V1298 Tau Planets

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    Mass, radius, and age measurements of young (<100 Myr) planets have the power to shape our understanding of planet formation. However, young stars tend to be extremely variable in both photometry and radial velocity, which makes constraining these properties challenging. The V1298 Tau system of four ~0.5 Rjup planets transiting a pre-main sequence star presents an important, if stress-inducing, opportunity to directly observe and measure the properties of infant planets. Su\'arez-Mascare\~no et al. (2021) published radial-velocity-derived masses for two of the V1298 Tau planets using a state-of-the-art Gaussian Process regression framework. The planetary densities computed from these masses were surprisingly high, implying extremely rapid contraction after formation in tension with most existing planet formation theories. In an effort to further constrain the masses of the V1298 Tau planets, we obtained 36 RVs using Keck/HIRES, and analyzed them in concert with published RVs and photometry. Through performing a suite of cross validation tests, we found evidence that the preferred model of SM21 suffers from overfitting, defined as the inability to predict unseen data, rendering the masses unreliable. We detail several potential causes of this overfitting, many of which may be important for other RV analyses of other active stars, and recommend that additional time and resources be allocated to understanding and mitigating activity in active young stars such as V1298 Tau.Comment: 26 pages, 12 figures; published in A

    The California Legacy Survey I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades

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    We present a high-precision radial velocity (RV) survey of 719 FGKM stars, which host 164 known exoplanets and 14 newly discovered or revised exoplanets and substellar companions. This catalog updated the orbital parameters of known exoplanets and long-period candidates, some of which have decades-longer observational baselines than they did upon initial detection. The newly discovered exoplanets range from warm sub-Neptunes and super-Earths to cold gas giants. We present the catalog sample selection criteria, as well as over 100,000 radial velocity measurements, which come from the Keck-HIRES, APF-Levy, and Lick-Hamilton spectrographs. We introduce the new RV search pipeline RVSearch that we used to generate our planet catalog, and we make it available to the public as an open-source Python package. This paper is the first study in a planned series that will measure exoplanet occurrence rates and compare exoplanet populations, including studies of giant planet occurrence beyond the water ice line, and eccentricity distributions to explore giant planet formation pathways. We have made public all radial velocities and associated data that we use in this catalog.Comment: Accepted to ApJ
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