587 research outputs found

    Search for associations containing young stars (SACY) VII. New stellar and substellar candidate members in the young associations

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    The young associations offer us one of the best opportunities to study the properties of young stellar and substellar objects and to directly image planets thanks to their proximity (<<200 pc) and age (≈\approx5-150 Myr). However, many previous works have been limited to identifying the brighter, more active members (≈\approx1 M⊙_\odot) owing to photometric survey sensitivities limiting the detections of lower mass objects. We search the field of view of 542 previously identified members of the young associations to identify wide or extremely wide (1000-100,000 au in physical separation) companions. We combined 2MASS near-infrared photometry (JJ, HH, KK) with proper motion values (from UCAC4, PPMXL, NOMAD) to identify companions in the field of view of known members. We collated further photometry and spectroscopy from the literature and conducted our own high-resolution spectroscopic observations for a subsample of candidate members. This complementary information allowed us to assess the efficiency of our method. We identified 84 targets (45: 0.2-1.3 M⊙_\odot, 17: 0.08-0.2 M⊙_\odot, 22: <<0.08 M⊙_\odot) in our analysis, ten of which have been identified from spectroscopic analysis in previous young association works. For 33 of these 84, we were able to further assess their membership using a variety of properties (X-ray emission, UV excess, Hα_\alpha, lithium and K I equivalent widths, radial velocities, and CaH indices). We derive a success rate of 76-88% for this technique based on the consistency of these properties. Once confirmed, the targets identified in this work would significantly improve our knowledge of the lower mass end of the young associations. Additionally, these targets would make an ideal new sample for the identification and study of planets around nearby young stars.Comment: 28 pages, 24 figures, accepted in A&

    An eccentric companion at the edge of the brown dwarf desert orbiting the 2.4 Msun giant star HIP67537

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    We report the discovery of a substellar companion around the giant star HIP67537. Based on precision radial velocity measurements from CHIRON and FEROS high-resolution spectroscopic data, we derived the following orbital elements for HIP67537 b\,b: mb_bsinii = 11.1−1.1+0.4^{+0.4}_{-1.1} Mjup_{\rm {\tiny jup}}, aa = 4.9−0.13+0.14^{+0.14}_{-0.13} AU and ee = 0.59−0.02+0.05^{+0.05}_{-0.02}. Considering random inclination angles, this object has ≳\gtrsim 65% probability to be above the theoretical deuterium-burning limit, thus it is one of the few known objects in the planet to brown-dwarf transition region. In addition, we analyzed the Hipparcos astrometric data of this star, from which we derived a minimum inclination angle for the companion of ∼\sim 2 deg. This value corresponds to an upper mass limit of ∼\sim 0.3 M⊙_\odot, therefore the probability that HIP67537 b\,b is stellar in nature is ≲\lesssim 7%. The large mass of the host star and the high orbital eccentricity makes HIP67537 b\,b a very interesting and rare substellar object. This is the second candidate companion in the brown dwarf desert detected in the sample of intermediate-mass stars targeted by the EXPRESS radial velocity program, which corresponds to a detection fraction of ff = 1.6−0.5+2.0^{+2.0}_{-0.5}%. This value is larger than the fraction observed in solar-type stars, providing new observational evidence of an enhanced formation efficiency of massive substellar companions in massive disks. Finally, we speculate about different formation channels for this object.Comment: Accepted for publication to A&

    Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars

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    CONTEXT. Exoplanet searches have demonstrated that giant planets are preferentially found around metal-rich stars and that their fraction increases with the stellar mass. AIMS. During the past six years, we have conducted a radial velocity follow-up program of 166 giant stars, to detect substellar companions, and characterizing their orbital properties. Using this information, we aim to study the role of the stellar evolution in the orbital parameters of the companions, and to unveil possible correlations between the stellar properties and the occurrence rate of giant planets. METHODS. Using FEROS and CHIRON spectra, we have computed precision radial velocities and we have derived atmospheric and physical parameters for all of our targets. Additionally, velocities computed from UCLES spectra are presented here. By studying the periodic radial velocity signals, we have detected the presence of several substellar companions. RESULTS. We present four new planetary systems around the giant stars HIP8541, HIP74890, HIP84056 and HIP95124. Additionally, we find that giant planets are more frequent around metal-rich stars, reaching a peak in the detection of ff = 16.7−5.9+15.5^{+15.5}_{-5.9}% around stars with [Fe/H] ∼\sim 0.35 dex. Similarly, we observe a positive correlation of the planet occurrence rate with the stellar mass, between M⋆_\star ∼\sim 1.0 -2.1 M⊙_\odot, with a maximum of ff = 13.0−4.2+10.1^{+10.1}_{-4.2}%, at M⋆_\star = 2.1 M⊙_\odot. CONCLUSIONS. We conclude that giant planets are preferentially formed around metal-rich stars. Also, we conclude that they are more efficiently formed around more massive stars, in the mass range of M⋆_\star ∼\sim 1.0 - 2.1 M⊙_\odot. These observational results confirm previous findings for solar-type and post-MS hosting stars, and provide further support to the core-accretion formation model.Comment: Accepted for publication in A&

    Pheochromocytoma, polycythemia and venous thrombosis

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    Polycythemia is rarely associated with pheochromocytoma. A patient with a 22-year history of malignant pheochromocytoma is presented in whom major complications developed as a result of long-standing polycythemia, apparently due to secretion of erythropoletin by the tumors. Despite attempts to reduce tumor burden by surgery, chemotherapy, and large doses of 1-131-metalodobenzyl guanidine, polycythemia persisted. Extensive venous thrombosis developed requiring hospitalization and anticoagulation. Thus, polycythemia itself may be a cause of major morbidity in patients with pheochromocytoma, and prophylactic measures may be warranted. Review of the 130 patients with benign and malignant pheochromocytoma studied since the introduction of I-131-metaiodobenzylguanidine in 1980 revealed another six patients with hematocrits over 50 but only one had a hematocrit greater than 55 and required regular phlebotomy. In contrast, anemia (hematocrit less than 35) due to variety of causes was present in 18 cases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26991/1/0000558.pd

    Multicultural immunisation: Liberalism and Esposito

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    Resummation Methods at Finite Temperature: The Tadpole Way

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    We examine several resummation methods for computing higher order corrections to the finite temperature effective potential, in the context of a scalar Ï•4\phi^4 theory. We show by explicit calculation to four loops that dressing the propagator, not the vertex, of the one-loop tadpole correctly counts ``daisy'' and ``super-daisy'' diagrams.Comment: 18 pages, LaTeX, CALT-68-1858, HUTP-93-A011, EFI-93-2

    Development of a Medication Monitoring System for an Integrated Multidisciplinary Program of Assertive Community Treatment (IMPACT) Team

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    Purpose: The primary goal was to improve medication management oversight for a severely mentally ill (SMI) community-based population by developing a medication monitoring system based on current guidelines to optimize pharmacotherapy and minimize potential medication-related adverse effects. The secondary goal was improvement in coordination of care between healthcare providers. Methods: Guidelines for medication used for psychiatric indications were reviewed. A database of medication for psychiatric indications with monitoring recommendation was developed. Results: Medication regimens for 68 members of the Integrated Multidisciplinary Program of Assertive Community Treatment (IMPACT) program qualified for review. Fourteen medications, carbamazepine, chlorpromazine, clozapine, fluphenazine and fluphenazine long-acting injections (LAI), haloperidol and haloperidol LAI, lithium, lurasidone, olanzapine, paliperidone and paliperidone LAI, perphenazine, quetiapine, risperidone and risperidone LAI, valproic acid/divalproex, and ziprasidone, were identified. In total, 111 medications are used on a monthly basis. Each member receives more than one medication qualifying for review. Additional monitoring parameters that were evaluated included changes in laboratory orders for members with insulin-dependent diabetes. Annual lipid panels were changed to every 6 months, if applicable. Conclusions and Future Directions: This medication monitoring program was developed to help ensure IMPACT members receive the most effective care and minimize potential medication-related adverse effects. The secondary goal was to improve coordination of care. Medication monitoring will be added as a continuous quality assurance measure. Lab results will be reviewed at least monthly. The medication monitoring program will be evaluated annually

    Development of a Medication Monitoring System for an Integrated Multidisciplinary Program of Assertive Community Treatment (IMPACT) Team

    Get PDF
    Purpose: The primary goal was to improve medication management oversight for a severely mentally ill (SMI) community-based population by developing a medication monitoring system based on current guidelines to optimize pharmacotherapy and minimize potential medication-related adverse effects. The secondary goal was improvement in coordination of care between healthcare providers. Methods: Guidelines for medication used for psychiatric indications were reviewed. A database of medication for psychiatric indications with monitoring recommendation was developed. Results: Medication regimens for 68 members of the Integrated Multidisciplinary Program of Assertive Community Treatment (IMPACT) program qualified for review. Fourteen medications, carbamazepine, chlorpromazine, clozapine, fluphenazine and fluphenazine long-acting injections (LAI), haloperidol and haloperidol LAI, lithium, lurasidone, olanzapine, paliperidone and paliperidone LAI, perphenazine, quetiapine, risperidone and risperidone LAI, valproic acid/divalproex, and ziprasidone, were identified. In total, 111 medications are used on a monthly basis. Each member receives more than one medication qualifying for review. Additional monitoring parameters that were evaluated included changes in laboratory orders for members with insulin-dependent diabetes. Annual lipid panels were changed to every 6 months, if applicable. Conclusions and Future Directions: This medication monitoring program was developed to help ensure IMPACT members receive the most effective care and minimize potential medication-related adverse effects. The secondary goal was to improve coordination of care. Medication monitoring will be added as a continuous quality assurance measure. Lab results will be reviewed at least monthly. The medication monitoring program will be evaluated annually. &nbsp; Type:&nbsp;Student Projec

    Orbital and physical parameters of eclipsing binaries from the ASAS catalogue - IX. Spotted pairs with red giants

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    We present spectroscopic and photometric solutions for three spotted systems with red giant components. Absolute physical and orbital parameters for these double-lined detached eclipsing binary stars are presented for the first time. These were derived from the V-, and I-band ASAS and WASP photometry, and new radial velocities calculated from high quality optical spectra we obtained with a wide range of spectrographs and using the two-dimensional cross-correlation technique (TODCOR). All of the investigated systems (ASAS J184949-1518.7, BQ Aqr, and V1207 Cen) show the differential evolutionary phase of their components consisting of a main-sequence star or a subgiant and a red giant, and thus constitute very informative objects in terms of testing stellar evolution models. Additionally, the systems show significant chromospheric activity of both components. They can be also classified as classical RS CVn-type stars. Besides the standard analysis of radial velocities and photometry, we applied spectral disentangling to obtain separate spectra for both components of each analysed system which allowed for a more detailed spectroscopic study. We also compared the properties of red giant stars in binaries that show spots, with those that do not, and found that the activity phenomenon is substantially suppressed for stars with Rossby number higher than ∼1 and radii larger than ∼20 R⊙
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