scholarly journals Precision angular diameters for 16 southern stars with VLTI/PIONIER

2020 ◽  
Vol 493 (2) ◽  
pp. 2377-2394
Author(s):  
Adam D Rains ◽  
Michael J Ireland ◽  
Timothy R White ◽  
Luca Casagrande ◽  
I Karovicova
Keyword(s):  
Broad Band ◽  
Unmet Need ◽  
High Signal ◽  
Correlated Errors ◽  
Single Star ◽  
Giant Stars ◽  
Stellar Diameters ◽  
Effective Temperatures ◽  
The Impact ◽  
Angular Diameters

ABSTRACT In the current era of Gaia and large, high signal-to-noise stellar spectroscopic surveys, there is an unmet need for a reliable library of fundamentally calibrated stellar effective temperatures based on accurate stellar diameters. Here, we present a set of precision diameters and temperatures for a sample of 6 dwarf, 5 sub-giant, and 5 giant stars observed with the PIONIER beam combiner at the VLTI. Science targets were observed in at least two sequences with five unique calibration stars each for accurate visibility calibration and to reduce the impact of bad calibrators. We use the standard PIONIER data reduction pipeline, but bootstrap over interferograms, in addition to employing a Monte Carlo approach to account for correlated errors by sampling stellar parameters, limb darkening coefficients, and fluxes, as well as predicted calibrator angular diameters. The resulting diameters were then combined with bolometric fluxes derived from broad-band Hipparcos–Tycho photometry and MARCS model bolometric corrections, plus parallaxes from Gaia to produce effective temperatures, physical radii, and luminosities for each star observed. Our stars have mean angular diameter and temperatures uncertainties of 0.8 per cent and 0.9 per cent, respectively, with our sample including diameters for 10 stars with no pre-existing interferometric measurements. The remaining stars are consistent with previous measurements, with the exception of a single star which we observe here with PIONIER at both higher resolution and greater sensitivity than was achieved in earlier work.

scholarly journals ANGULAR DIAMETERS AND EFFECTIVE TEMPERATURES OF 25 K GIANT STARS FROM THE CHARA ARRAY

2010 ◽  
Vol 710 (2) ◽  
pp. 1365-1374 ◽  
Author(s):  
Ellyn K. Baines ◽  
Michaela P. Döllinger ◽  
Felice Cusano ◽  
Eike W. Guenther ◽  
Artie P. Hatzes ◽  
...  
Keyword(s):  
Giant Stars ◽  
Effective Temperatures ◽  
Chara Array ◽  
Angular Diameters

scholarly journals Rubidium abundances in solar metallicity stars

2021 ◽  
Vol 648 ◽  
pp. A107
Author(s):  
C. Abia ◽  
P. de Laverny ◽  
S. Korotin ◽  
A. Asensio Ramos ◽  
A. Recio-Blanco ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
Magnetic Activity ◽  
Point Of View ◽  
Asymptotic Giant Branch ◽  
High Signal ◽  
Asymptotic Giant Branch Stars ◽  
M Dwarfs ◽  
Giant Stars ◽  
Solar Metallicity ◽  
The Impact

Context. Rubidium is one of the few elements produced by the neutron capture s- and r-processes in almost equal proportions. Recently, a Rb deficiency ([Rb/Fe] < 0.0), amounting to a factor of about two with respect to the Sun, has been found in M dwarfs of near-solar metallicity. This stands in contrast to the close-to-solar [Sr, Zr/Fe] ratios derived in the same stars. This deficiency is difficult to understand from the point of view of observations and of nucleosynthesis. Aims. To test the reliability of this Rb deficiency, we study the Rb and Zr abundances in a sample of KM-type giant stars across a similar metallicity range, extracted from the AMBRE Project. Methods. We used high-resolution and high signal-to-noise spectra to derive Rb and Zr abundances in a sample of 54 bright giant stars with metallicities in the range of −0.6 ≲ [Fe/H] ≲ +0.4 dex, via spectral synthesis in both local and non-local thermodynamic equilibrium (LTE and NLTE, respectively). We also studied the impact of the Zeeman broadening in the profile of the Rb I at λ7800 Å line. Results. The LTE analysis also results in a Rb deficiency in giant stars, however, it is considerably lower than that obtained in M dwarfs. However, once NLTE corrections are performed, the [Rb/Fe] ratios are very close to solar (average −0.01 ± 0.09 dex) in the full metallicity range studied here. This stands in contrast to the value found for M dwarfs. The [Zr/Fe] ratios derived are in excellent agreement with those obtained in previous studies in FGK dwarf stars with a similar metallicity. We investigate the effect of gravitational settling and magnetic activity as possible causes of the Rb deficiency found in M dwarfs. Although the former phenomenon has a negligible impact on the surface Rb abundance, the presence of an average magnetic field with an intensity that is typical of that observed in M dwarfs may result in systematic Rb abundance underestimations if the Zeeman broadening is not considered in the spectral synthesis. This may explain the Rb deficiency in M dwarfs, but not fully. On the other hand, the new [Rb/Fe] and [Rb/Zr] versus [Fe/H] relationships can be explained when the Rb production by rotating massive stars and low-to-intermediate mass stars (these latter also producing Zr) are considered, without the need to deviate from the standard s-process nucleosynthesis in asymptotic giant branch stars, as suggested previously.

Impact of the convective mixing-length parameter α on stellar metallicity

2020 ◽  
Vol 635 ◽  
pp. A176 ◽  
Author(s):  
N. Song ◽  
S. Alexeeva ◽  
T. Sitnova ◽  
L. Wang ◽  
F. Grupp ◽  
...  
Keyword(s):  
Open Cluster ◽  
Synthesis Method ◽  
Stellar Atmospheres ◽  
High Signal ◽  
Mixing Length ◽  
Dwarf Stars ◽  
Giant Stars ◽  
Spectrum Synthesis ◽  
Mixing Length Theory ◽  
The Impact

Context. Mixing-length theory is used to treat stellar convection. As a simulation in one-dimensional stellar atmospheres models, the mixing-length parameter α is calibrated from the Sun and then applied to other stars. However, there is no strong evidence to suggest that α should be the same for stars of different evolutionary stages. Aims. We evaluate the impact of the α value on the metallicity of different types of stars and investigate the correlation between the metallicity discrepancy (Δ[Fe∕H]) and stellar parameters (Teff, log g). Methods. We selected ten well-studied field stars and one open cluster of nine members for which high-resolution and high signal-to-noise spectra are available. The model atmospheres were calculated with the code MAFAGS-OS. We derived iron abundances from Fe I and Fe II lines both under local thermodynamic equilibrium and non-LTE conditions using a spectrum synthesis method. After deriving [Fe/H] for each line, we calculated Δ[Fe∕H] with two different α values, fixed solar-calibrated α, and α obtained for each star individually. Finally, we investigated the correlation between Δ[Fe∕H] caused by revised α with stellar parameters. Results. For FGK dwarf stars, the Δ[Fe∕H] caused by the α correction is less than 0.02 dex, while for turn-off and giant stars, the Δ[Fe∕H] values are no more than 0.03 dex, which are lower than typical uncertainties in metallicity. For main-sequence stars, Δ[Fe∕H] versus Teff and Δ[Fe∕H] versus log g are well fit by linear relations.

scholarly journals Family reported outcomes, an unmet need in the management of a patient's disease: appraisal of the literature

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
R. Shah ◽  
F. M. Ali ◽  
A. Y. Finlay ◽  
M. S. Salek
Keyword(s):  
Quality Of Life ◽  
Family Members ◽  
Unmet Need ◽  
Reliability And Validity ◽  
Chronic Health Condition ◽  
Family Quality Of Life ◽  
Good Reliability ◽  
Huge Impact ◽  
The Impact

Abstract Background A person’s chronic health condition or disability can have a huge impact on the quality of life (QoL) of the whole family, but this important impact is often ignored. This literature review aims to understand the impact of patients' disease on family members across all medical specialities, and appraise existing generic and disease-specific family quality of life (QoL) measures. Methods The databases Medline, EMBASE, CINHAL, ASSIA, PsycINFO and Scopus were searched for original articles in English measuring the impact of health conditions on patients' family members/partner using a valid instrument. Results Of 114 articles screened, 86 met the inclusion criteria. They explored the impact of a relative's disease on 14,661 family members, mostly 'parents' or 'mothers', using 50 different instruments across 18 specialities including neurology, oncology and dermatology, in 33 countries including the USA, China and Australia. These studies revealed a huge impact of patients' illness on family members. An appraisal of family QoL instruments identified 48 instruments, 42 disease/speciality specific and six generic measures. Five of the six generics are aimed at carers of children, people with disability or restricted to chronic disease. The only generic instrument that measures the impact of any condition on family members across all specialities is the Family Reported Outcome Measure (FROM-16). Although most instruments demonstrated good reliability and validity, only 11 reported responsiveness and only one reported the minimal clinically important difference. Conclusions Family members' QoL is greatly impacted by a relative's condition. To support family members, there is a need for a generic tool that offers flexibility and brevity for use in clinical settings across all areas of medicine. FROM-16 could be the tool of choice, provided its robustness is demonstrated with further validation of its psychometric properties.

scholarly journals THU0528 NAILFOLD VIDEOCAPILLAROSCOPY REPORTING IN CLINICAL RESEARCH: INTERNATIONAL DELPHI BASED CONSENSUS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 503.1-504
Author(s):  
F. Ingegnoli ◽  
T. Schioppo ◽  
A. Herrick ◽  
A. Sulli ◽  
F. Bartoli ◽  
...  
Keyword(s):  
Systematic Review ◽  
Clinical Research ◽  
Rheumatic Diseases ◽  
Unmet Need ◽  
Future Research ◽  
Invasive Technique ◽  
Delphi Consensus ◽  
Research Support ◽  
The Impact ◽  
Research Studies

Background:Nailfold capillaroscopy (NVC), a non-invasive technique to assess microcirculation, is increasingly being incorporated into rheumatology routine clinical practice. Currently, the degree of description of NVC methods varies amongst research studies, making interpretation and comparison between studies challenging. In this field, an unmet need is the standardization of items to be reported in research studies using NVC.Objectives:To perform a Delphi consensus on minimum reporting standards in methodology for clinical research, based on the items derived from a systematic review focused on this topic.Methods:The systematic review of the literature on NVC methodology relating to rheumatic diseases was performed according to PRISMA guidelines (PROSPERO CRD42018104660) to July 22nd2018 using MEDLINE, Embase, Scopus. Then, a three-step web-based Delphi consensus was performed in between members of the EULAR study group on microcirculation in rheumatic diseases and the Scleroderma Clinical Trials Consortium. Participants were asked to rate each item from 1 (not appropriate) to 9 (completely appropriate).Results:In total, 3491 references were retrieved in the initial search strategy, 2862 were excluded as duplicates or after title/abstract screening. 632 articles were retrieved for full paper review of which 319 fulfilled the inclusion criteria. Regarding patient preparation before the exam, data were scarce: 38% reported acclimatization, 5% to avoid caffeine and smoking, 3% to wash hands and 2% to avoid manicure. Concerning the device description: 90% reported type of instrument, 77% brand/model, 72% magnification, 46% oil use, 40% room temperature and 35% software for image analysis. As regards to examination details: 76% which fingers examined, 75% number of fingers examined, 15% operator experience, 13% reason for finger exclusion, 9% number of images, 8% quality check of the images and 3% time spent for the exam. Then, a three-round Delphi consensus on the selected items was completed by 80 participants internationally, from 31 countries located in Australia, Asia, Europe, North and South America. Some items reached the agreement at the second round (85 participants), and other items were suggested as important to consider in a future research agenda (e.g. temperature for acclimatization, the impact of smoking, allergies at the application of the oil to the nailbed, significance of pericapillary edema, methods of reporting hemorrhages, ramified and giant capillaries). The final agreement results are reported below:Conclusion:On the basis of the available literature the description of NVC methods was highly heterogeneous and individual published studies differed markedly. These practical suggestions developed using a Delphi process among international participants provide a guidance to improve and to standardize the NVC methodology in future clinical research studies.Disclosure of Interests:Francesca Ingegnoli: None declared, Tommaso Schioppo: None declared, Ariane Herrick: None declared, Alberto Sulli Grant/research support from: Laboratori Baldacci, Francesca Bartoli: None declared, Nicola Ughi: None declared, John Pauling: None declared, Maurizio Cutolo Grant/research support from: Bristol-Myers Squibb, Actelion, Celgene, Consultant of: Bristol-Myers Squibb, Speakers bureau: Sigma-Alpha, Vanessa Smith Grant/research support from: The affiliated company received grants from Research Foundation - Flanders (FWO), Belgian Fund for Scientific Research in Rheumatic diseases (FWRO), Boehringer Ingelheim Pharma GmbH & Co and Janssen-Cilag NV, Consultant of: Boehringer-Ingelheim Pharma GmbH & Co, Speakers bureau: Actelion Pharmaceuticals Ltd, Boehringer-Ingelheim Pharma GmbH & Co and UCB Biopharma Sprl

scholarly journals Searching for energy-resolved quasi-periodic oscillations in AGN

2021 ◽  
Author(s):  
Dominic I Ashton ◽  
Matthew J Middleton
Keyword(s):  
Power Law ◽  
Spectral Component ◽  
Broad Band ◽  
Initial Study ◽  
Periodic Oscillations ◽  
Single Observation ◽  
Curved Space ◽  
Multiple Observations ◽  
Band Noise ◽  
The Impact

Abstract X-ray quasi-periodic oscillations (QPOs) in AGN allow us to probe and understand the nature of accretion in highly curved space-time, yet the most robust form of detection (i.e. repeat detections over multiple observations) has been limited to a single source to-date, with only tentative claims of single observation detections in several others. The association of those established AGN QPOs with a specific spectral component has motivated us to search the XMM-Newton archive and analyse the energy-resolved lightcurves of 38 bright AGN. We apply a conservative false alarm testing routine folding in the uncertainty and covariance of the underlying broad-band noise. We also explore the impact of red-noise leak and the assumption of various different forms (power-law, broken power-law and lorentzians) for the underlying broad-band noise. In this initial study, we report QPO candidates in 6 AGN (7 including one tentative detection in MRK 766) from our sample of 38, which tend to be found at characteristic energies and, in four cases, at the same frequency across at least two observations, indicating they are highly unlikely to be spurious in nature.

scholarly journals Prevalence vs impact: a mixed methods study of survivorship issues in colorectal cancer

2021 ◽  
Author(s):  
Amanda Drury ◽  
Sheila Payne ◽  
Anne-Marie Brady
Keyword(s):  
Mixed Methods ◽  
Unmet Need ◽  
Bowel Dysfunction ◽  
Structured Interviews ◽  
Daily Lives ◽  
Negative Body Image ◽  
Cross Domain ◽  
Cancer Support ◽  
Need Support ◽  
The Impact

Abstract Purpose This study aims to explore the prevalence of CRC survivorship issues and their impact on survivors’ quality of life (QoL). Methods This study utilised a mixed methods sequential explanatory design. Adult CRC survivors between 6- and 60-months post-diagnosis (n = 304) were purposively recruited from three hospitals and twenty-one cancer support centres in Ireland. QoL was evaluated using the EuroQol and FACT-C questionnaires and results compared to population norms. 22 survey participants took part in semi-structured interviews exploring the impact of survivorship issues on their daily lives. Results While CRC survivors reported QoL outcomes comparable to or better than normative populations, 54% were dissatisfied with their QoL. The most common survivorship issues reported included negative body image (74%), fatigue (68%), sexual dysfunction (66%) and sleep disturbance (59%). Thematic analysis of the qualitative data illustrated survivors’ attempts to live with the impact of cancer and its treatment (loss, fear, impact) and striving to contextualise, reframe and understand the consequences of cancer and its treatment (control, vigilance, benefit). Within these themes, the cross-domain impact of less prevalent symptoms including bowel dysfunction (28–57%) and peripheral neuropathy (47%) were widely discussed. Conclusions Although cancer survivors report positive QoL outcomes, many experience distressing physical, psychological and social effects. The findings suggest less common and difficult to manage symptoms are the greatest source of distress and unmet need. Support and information must be tailored to address survivors’ individual needs and preferences for support, informed by holistic person-centred assessment.

scholarly journals Retrieving Forest Canopy Elements Clumping Index Using ICESat GLAS Lidar Data

2021 ◽  
Vol 13 (5) ◽  
pp. 948
Author(s):  
Lei Cui ◽  
Ziti Jiao ◽  
Kaiguang Zhao ◽  
Mei Sun ◽  
Yadong Dong ◽  
...  
Keyword(s):  
Large Scale ◽  
Forest Canopy ◽  
Remote Sensing Data ◽  
Alternative Methods ◽  
High Signal ◽  
Laser Altimeter ◽  
Waveform Data ◽  
Forest Park ◽  
Clumping Index ◽  
The Impact

Clumping index (CI) is a canopy structural variable important for modeling the terrestrial biosphere, but its retrieval from remote sensing data remains one of the least reliable. The majority of regional or global CI products available so far were generated from multiangle optical reflectance data. However, these reflectance-based estimates have well-known limitations, such as the mere use of a linear relationship between the normalized difference hotspot and darkspot (NDHD) and CI, uncertainties in bidirectional reflectance distribution function (BRDF) models used to calculate the NDHD, and coarse spatial resolutions (e.g., hundreds of meters to several kilometers). To remedy these limitations and develop alternative methods for large-scale CI mapping, here we explored the use of spaceborne lidar—the Geoscience Laser Altimeter System (GLAS)—and proposed a semi-physical algorithm to estimate CI at the footprint level. Our algorithm was formulated to leverage the full vertical canopy profile information of the GLAS full-waveform data; it converted raw waveforms to forest canopy gap distributions and gap fractions of random canopies, which was used to estimate CI based on the radiative transfer theory and a revised Beer–Lambert model. We tested our algorithm over two areas in China—the Saihanba National Forest Park and Heilongjiang Province—and assessed its relative accuracies against field-measured CI and MODIS CI products. We found that reliable estimation of CI was possible only for GLAS waveforms with high signal-to-noise ratios (e.g., >65) and at gentle slopes (e.g., <12°). Our GLAS-based CI estimates for high-quality waveforms compared well to field-based CI (i.e., R2 = 0.72, RMSE = 0.07, and bias = 0.02), but they showed less correlation to MODIS CI (e.g., R2 = 0.26, RMSE = 0.12, and bias = 0.04). The difference highlights the impact of the scale effect in conducting comparisons of products with huge differences resolution. Overall, our analyses represent the first attempt to use spaceborne lidar to retrieve high-resolution forest CI and our algorithm holds promise for mapping CI globally.

The Effective Temperature of Dust Impact Plasmas — Olivine Dust on Tungsten Target

2021 ◽  
Author(s):  
Jiří Pavlů ◽  
Samuel Kočiščák ◽  
Åshild Fredriksen ◽  
Michael DeLuca ◽  
Zoltan Sternovsky
Keyword(s):  
Negative Charge ◽  
Negative Ions ◽  
Charge Carriers ◽  
Dust Particles ◽  
Applied Bias ◽  
Control Grid ◽  
Impact Speed ◽  
Positive Ions ◽  
Effective Temperatures ◽  
The Impact

&lt;p&gt;We experimentally observe both positive and negative charge carriers in impact plasma and estimate their effective temperatures. The measurements are carried on a dust accelerator using polypyrrole (PPy)-coated olivine dust particles impacting tungsten (W) target in the velocity range of 2&amp;#8211;18 km/s. We measure the retained impact charge as a function of applied bias potential to the control grid. The temperatures are estimated from the data fit. The estimated effective temperatures of the positive ions are approximately 7&amp;#160;eV and seems to be independent of the impact speed. The negative charge carriers' temperatures vary from as low as 1 eV for the lowest speeds to almost ten times higher speeds. The presented values differ significantly from previous studies using Fe dust particles. Yet, the discrepancy can be attributed to a larger fraction of negative ions in the impact plasma that likely originates from the PPy coating.&lt;/p&gt;

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