233 research outputs found

    Oblique Propagation and Refraction of Gravity Waves Over the Andes Observed by GLORIA and ALIMA During the SouthTRAC Campaign

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    Gravity waves (GW) carry energy and momentum from the troposphere to the middle atmosphere and have a strong influence on the circulation there. Global atmospheric models cannot fully resolve GWs, and therefore rely on highly simplified GW parametrizations that, among other limitations, account for vertical wave propagation only and neglect refraction. This is a major source of uncertainty in models, and leads to well-known problems, such as the late break-up of polar vortex due to the “missing” GW drag around 60°S. To investigate these phenomena, GW observations over Southern Andes were performed during SouthTRAC aircraft campaign. This paper presents measurements from a SouthTRAC flight on 21 September 2019, including 3-D tomographic temperature data of the infrared limb imager GLORIA (8–15 km altitude) and temperature profiles of the ALIMA lidar (20–80 km altitude). GLORIA observations revealed multiple overlapping waves of different wavelengths. 3-D wave vectors were determined from the GLORIA data and used to initialize a GW ray-tracer. The ray-traced GW parameters were compared with ALIMA observations, showing good agreement between the instruments and direct evidence of oblique (partly meridional) GW propagation. ALIMA data analysis confirmed that most waves at 25–40 km altitudes were indeed orographic GWs, including waves seemingly upstream of the Andes. We directly observed horizontal GW refraction, which has not been achieved before SouthTRAC. Refraction and oblique propagation caused significant meridional transport of horizontal momentum as well as horizontal momentum exchange between waves and the background flow all along the wave paths, not just in wave excitation and breaking regions

    First Observation of Planet-Induced X-ray Emission: The System HD 179949

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    We present the first observation of planet-induced stellar X-ray activity, identified for the HD 179949 system, using Chandra / ACIS-S. The HD 179949 system consists of a close-in giant planet orbiting an F9V star. Previous ground-based observations already showed enhancements in Ca II K in phase with the planetary orbit. We find an ~30% increase in the X-ray flux over quiescent levels coincident with the phase of the Ca II enhancements. There is also a trend for the emission to be hotter at increased fluxes, confirmed by modeling, showing the enhancement at ~1 keV compared to ~0.4 keV for the background star.Comment: 3 pages, 1 figure; Exoplanets: Detection, Formation and Dynamics, IAU Symposium 249, eds. Y.-S. Sun, S. Ferraz-Mello, and J.-L. Zhou (Cambridge: Cambridge University Press

    Planet-Induced Emission Enhancements in HD 179949: Results from McDonald Observations

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    We monitored the Ca II H and K lines of HD 179949, a notable star in the southern hemisphere, to observe and confirm previously identified planet induced emission (PIE) as an effect of star-planet interaction. We obtained high resolution spectra (R ~ 53,000) with a signal-to-noise ratio S/N >~ 50 in the Ca II H and K cores during 10 nights of observation at the McDonald Observatory. Wide band echelle spectra were taken using the 2.7 m telescope. Detailed statistical analysis of Ca II K revealed fluctuations in the Ca II K core attributable to planet induced chromospheric emission. This result is consistent with previous studies by Shkolnik et al. (2003). Additionally, we were able to confirm the reality and temporal evolution of the phase shift of the maximum of star-planet interaction previously found. However, no identifiable fluctuations were detected in the Ca II H core. The Al I lambda 3944 A line was also monitored to gauge if the expected activity enhancements are confined to the chromospheric layer. Our observations revealed some variability, which is apparently unassociated with planet induced activity.Comment: 11 pages, 11 figures, 5 tables; Publications of the Astronomical Society of Australia (in press

    Technological Resources and Personnel Costs Required to Implement an Automated Alert System for Primary Care Physicians When Patients Transition from Hospitals to Home

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    Background With the adoption of electronic medical records by medical group practices, there are opportunities to improve the quality of care for patients discharged from hospitals. However, there is little guidance for medical groups outside of integrated hospital systems to automate the flow of patient information during transitions in care. Objective To describe the technological resources, expertise and time needed to develop an automated system providing information to primary care physicians when their patients transition from hospitals to home. Development Within a medical group practice, we developed an automated alert system that provides notification of discharges, reminders of the need for follow-up visits, drugs added during in-patient stays, and recommendations for laboratory monitoring of high risk drugs. We tracked components of the information system required and the time spent by team members. We used US national averages of hourly wages to estimate personnel costs. Application Critical components of the information system are notifications of hospital discharges through an admission, discharge and transfer registration (ADT) interface, linkage to the practice’s scheduling system, access to information on pharmacy dispensing and lab tests, and an interface engine. Total personnel cost was $76,314. Nearly half (47%) was for 614 hours by physicians who developed content, provided overall project management, and reviewed alerts to ensure that only “actionable” alerts would be sent. Conclusion Implementing a system to provide information about patient transitions requires strong internal informatics expertise, cooperation between facilities and ambulatory providers, development of electronic linkages, and extensive commitment of physician time

    Models of Star-Planet Magnetic Interaction

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    Magnetic interactions between a planet and its environment are known to lead to phenomena such as aurorae and shocks in the solar system. The large number of close-in exoplanets that were discovered triggered a renewed interest in magnetic interactions in star-planet systems. Multiple other magnetic effects were then unveiled, such as planet inflation or heating, planet migration, planetary material escape, and even modification of the host star properties. We review here the recent efforts in modelling and understanding magnetic interactions between stars and planets in the context of compact systems. We first provide simple estimates of the effects of magnetic interactions and then detail analytical and numerical models for different representative scenarii. We finally lay out a series of future developments that are needed today to better understand and constrain these fascinating interactions.Comment: 23 pages, 10 figures, accepted as a chapter in the Handbook of Exoplanet

    Patient Adherence to Laboratory Tests to Monitor Medication Therapy: A Mixed-Methods Study

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    Background Little is known about the contribution of patient behavior to incomplete laboratory monitoring and the reasons for patient non-completion of ordered laboratory tests remain unclear. Objective To describe factors, including patient-reported reasons, associated with non-completion of ordered laboratory tests. Design Mixed-methods study including a quantitative assessment of the frequency of patient adherence to ordered monitoring tests combined with qualitative, semi-structured, patient interviews. Participants Quantitative assessment included patients 18 years or older from a large multispecialty group practice prescribed a medication requiring monitoring. Qualitative interviews included a subset of adherent and non-adherent patients prescribed a cardiovascular, anti-convulsant, or thyroid replacement medication. Main Measures Proportion of recommended monitoring tests for each medication not completed, factors associated with patient non-adherence, and patient-reported reasons for non-adherence. Results Of 27,802 patients who were prescribed one of 34 medications, patient non-completion of ordered tests varied (range: 0% to 29%, by drug-test pair). Factors associated with higher odds of test non-completion included younger patient age (\u3c 40 years vs. ≥80 years, adjusted odds ratio [AOR] 1.52, 95% confidence interval [95% CI] 1.27-1.83), lower medication burden (1 medication vs. more than 1 drug, AOR for non-completion 1.26, 95% CI 1.15-1.37), and lower visit frequency (0-5 visits/year vs. ≥19 visits/year, AOR 1.41, 95% CI 1.25 to 1.59). Drug-test pairs with black box warning status were associated with greater odds of non-completion compared to drugs included only in the PDR (AOR 1.91, 95% CI 1.66-2.19). Qualitative interviews, with 16 non-adherent and 7 adherent patients, identified forgetting as the main cause of non-adherence. Conclusions Patient non-adherence contributed to missed opportunities to monitor medications and was associated with younger patient age and lower medication burden and black box warning status. Interventions to improve laboratory monitoring should target patients as well as physicians

    Magnetic field, differential rotation and activity of the hot-Jupiter hosting star HD 179949

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    HD 179949 is an F8V star, orbited by a giant planet at ~8 R* every 3.092514 days. The system was reported to undergo episodes of stellar activity enhancement modulated by the orbital period, interpreted as caused by Star-Planet Interactions (SPIs). One possible cause of SPIs is the large-scale magnetic field of the host star in which the close-in giant planet orbits. In this paper we present spectropolarimetric observations of HD 179949 during two observing campaigns (2009 September and 2007 June). We detect a weak large-scale magnetic field of a few Gauss at the surface of the star. The field configuration is mainly poloidal at both observing epochs. The star is found to rotate differentially, with a surface rotation shear of dOmega=0.216\pm0.061 rad/d, corresponding to equatorial and polar rotation periods of 7.62\pm0.07 and 10.3\pm0.8 d respectively. The coronal field estimated by extrapolating the surface maps resembles a dipole tilted at ~70 degrees. We also find that the chromospheric activity of HD 179949 is mainly modulated by the rotation of the star, with two clear maxima per rotation period as expected from a highly tilted magnetosphere. In September 2009, we find that the activity of HD 179949 shows hints of low amplitude fluctuations with a period close to the beat period of the system.Comment: Accepted for publication in Monthly Notices of The Royal Astronomical Societ

    Intervention to Reduce Adverse Outcomes among Older Adults Discharged from Skilled Nursing Facilities to Home

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    Background: Older adults may be at risk for adverse outcomes after discharge from skilled nursing facilities (SNF), but little research has focused on this transition. Objective: To assess the impact of an alert system on the rates of adverse outcomes among older adults discharged from SNFs to home. Methods: Within a multispecialty group practice, we tracked 30-day re-hospitalizations after SNF discharges during an intervention that provided discharge alerts to primary care physicians. We compared them to discharges from the pre-intervention period matched on age, gender and SNF. For the first 100 intervention discharges and their matches, we performed chart reviews to identify adverse drug events (ADEs). Multivariate analyses controlled for age, gender and intervention status. Results: We matched 313 intervention SNF discharges to 313 previous discharges. There was a slight reduction in the rate of 30-day re-hospitalization (30% vs. 31%) adjusted. Within the ADE study, 30% of the discharges during the intervention period and 30% of matched discharges had ADEs within 45 days. Among the 83 ADEs identified, 28% were deemed preventable; 69% resulted in symptom duration more than one day; 69% occurred within the first 14 days after discharge. This was a highly vulnerable population: mean age 82.5 (standard deviation (SD) 6.7); mean number of prescribed medications 11.9 (SD 8); 17% had Charlson Comorbidity Scores of ≥4. Common clinical conditions included myocardial infarction (24%), heart failure (22%), COPD (23%), and major depression (28%). Patients with scores of ≥4 were more likely to experience an ADE than those with lower scores (adjusted OR 2.5 (CI 1.2, 5.5), RD 0.21). Conclusion: Simply providing alerts when these vulnerable patients are discharged from SNFs is not sufficient to lower rates of adverse outcomes. Further research is required to track trajectories and identify additional points for interventions
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