1,940 research outputs found

    Orbital Elements and Stellar Parameters of the Active Binary UX Arietis

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    This is the final version of the article. Available from American Astronomical Society via the DOI in this record.Stellar activity observed as large surface spots, radio flares, or emission lines is often found in binary systems. UX Arietis exhibits these signs of activity, originating on the K0 subgiant primary component. Our aim is to resolve the binary, measure the orbital motion, and provide accurate stellar parameters such as masses and luminosities to aid in the interpretation of the observed phenomena. Using the CHARA six-telescope optical long-baseline array on Mount Wilson, California, we obtained amplitudes and phases of the interferometric visibility on baselines up to 330 m in length, resolving the two components of the binary. We reanalyzed archival Center for Astrophysics spectra to disentangle the binary component spectra and the spectrum of the third component, which was resolved by speckle interferometry. We also obtained new spectra with the Nordic Optical Telescope, and we present new photometric data that we use to model stellar surface spot locations. Both interferometric visibilities and spectroscopic radial velocities are modeled with a spotted primary stellar surface using the Wilson–Devinney code. We fit the orbital elements to the apparent orbit and radial velocity data to derive the distance (52.1 ± 0.8 pc) and stellar masses (MP = 1.30 0.06 M, MS = 1.14 0.06 M). The radius of the primary can be determined to be RP = 5.6 0.1 R and that of the secondary to be RS = 1.6 0.2 R. The equivalent spot coverage of the primary component was found to be 62% with an effective temperature 20% below that of the unspotted surface.We thank Robert Wilson (University of Florida) for providing a custom version of his code to compute images of spotted stellar surfaces and for his help with using it. This work is based upon observations obtained with the Georgia State University (GSU) Center for High Angular Resolution Astronomy (CHARA) array at Mount Wilson Observatory. The CHARA array is supported by the National Science Foundation under grant numbers AST-1211929 and AST-1411654. Institutional support has been provided by the GSU College of Arts and Sciences and the GSU Office of the Vice President for Research and Economic Development. The MIRC instrument at the CHARA array was funded by the University of Michigan. F.B., R.R., and J.D.M. acknowledge support from NSF-AST 1210972 and 1108963. G.T. acknowledges partial support from NSF grant AST-1509375. S.K. acknowledges support from an STFC Rutherford Fellowship (ST/J004030/1) and ERC Starting Grant (grant agreement no. 639889). This work is also based on observations made with the Nordic Optical Telescope (NOT), operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. This research has made use of the SIMBAD database, operated at the CDS, Strasbourg, France. This research has made use of the Jean-Marie Mariotti Center SearchCal service13 codeveloped by FIZEAU and LAOG/IPAG and of the CDS astronomical databases SIMBAD and VIZIER.14 This research has made use of the Washington Double Star Catalog, maintained at the U.S. Naval Observatory. We thank Nicholas Elias II for discussions. We thank Dimitri Pourbaix for maintaining and providing access to the SB9 database of RV measurements of spectroscopic binaries

    Very Cold Gas and Dark Matter

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    We have recently proposed a new candidate for baryonic dark matter: very cold molecular gas, in near-isothermal equilibrium with the cosmic background radiation at 2.73 K. The cold gas, of quasi-primordial abundances, is condensed in a fractal structure, resembling the hierarchical structure of the detected interstellar medium. We present some perspectives of detecting this very cold gas, either directly or indirectly. The H2_2 molecule has an "ultrafine" structure, due to the interaction between the rotation-induced magnetic moment and the nuclear spins. But the lines fall in the km domain, and are very weak. The best opportunity might be the UV absorption of H2_2 in front of quasars. The unexpected cold dust component, revealed by the COBE/FIRAS submillimetric results, could also be due to this very cold H2_2 gas, through collision-induced radiation, or solid H2_2 grains or snowflakes. The γ\gamma-ray distribution, much more radially extended than the supernovae at the origin of cosmic rays acceleration, also points towards and extended gas distribution.Comment: 16 pages, Latex pages, crckapb macro, 3 postscript figures, uuencoded compressed tar file. To be published in the proceeedings of the "Dust-Morphology" conference, Johannesburg, 22-26 January, 1996, D. Block (ed.), (Kluwer Dordrecht

    Optical Magnetometry

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    Some of the most sensitive methods of measuring magnetic fields utilize interactions of resonant light with atomic vapor. Recent developments in this vibrant field are improving magnetometers in many traditional areas such as measurement of geomagnetic anomalies and magnetic fields in space, and are opening the door to new ones, including, dynamical measurements of bio-magnetic fields, detection of nuclear magnetic resonance (NMR), magnetic-resonance imaging (MRI), inertial-rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of Nature.Comment: 11 pages; 4 figures; submitted to Nature Physic

    Visual ecology of aphids – a critical review on the role of colours in host finding

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    We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms. Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region. We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphid–tree interactions imply far-reaching assumptions on aphid responses to colours that are not likely to hold. Finally we also discuss the implications for developing and optimising strategies of aphid control and monitoring

    The experience and management of neck pain in general practice: the patients’ perspective

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    The objective of this study is to investigate the perspective and expectation of patients presenting with neck pain in general practice. The study design is a qualitative analysis of patient interviews and was conducted in a primary care setting in Germany. Twenty patients aged 20–78, according to theoretical sampling were included in the study. Patients tried to cope autonomously with the situation and consulted GPs only if their self-help had failed. When patients asked for external help, they usually focused on somatic treatment options such as massage, physiotherapy or injections. Most patients reported to have experiences with somatic therapies; however, they felt that some or all of these treatments were inefficient or led only to short-time improvements. Patients often avoided psychosocial themes when talking to doctors for fear of being branded as ‘neurotic’. Although neck pain is difficult to manage and a burden for patients, they have obviously found a way of both living with their pain and a pragmatic approach of talking about their symptoms with their doctor. According to the patients’ statements, the interaction between doctor and patient seems to be rather distant, ensuring that both sides avoid any issues that might touch upon psychological aspects of neck pain

    The increasing importance of atmospheric demand for ecosystem water and carbon fluxes

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    Soil moisture supply and atmospheric demand for water independently limit—and profoundly affect—vegetation productivity and water use during periods of hydrologic stress1, 2, 3, 4. Disentangling the impact of these two drivers on ecosystem carbon and water cycling is difficult because they are often correlated, and experimental tools for manipulating atmospheric demand in the field are lacking. Consequently, the role of atmospheric demand is often not adequately factored into experiments or represented in models5, 6, 7. Here we show that atmospheric demand limits surface conductance and evapotranspiration to a greater extent than soil moisture in many biomes, including mesic forests that are of particular importance to the terrestrial carbon sink8, 9. Further, using projections from ten general circulation models, we show that climate change will increase the importance of atmospheric constraints to carbon and water fluxes in all ecosystems. Consequently, atmospheric demand will become increasingly important for vegetation function, accounting for >70% of growing season limitation to surface conductance in mesic temperate forests. Our results suggest that failure to consider the limiting role of atmospheric demand in experimental designs, simulation models and land management strategies will lead to incorrect projections of ecosystem responses to future climate conditions

    The effects of nationality differences and work stressors on work adjustment for foreign nurse aides

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    <p>Abstract</p> <p>Background</p> <p>The main purpose of this study was to discuss the nationality differences of foreign nurse aides and the effect of work stressors influencing work adjustment. And of helping them adapt to Taiwanese society, we summarized the difficulties that foreign nurse aides face in Taiwan.</p> <p>Methods</p> <p>The subjects included 80 foreign nurse aides from the Philippines, Indonesia, and Vietnam who worked in long-term care facilities in Tao Yuan County. We recruited volunteers at the participating facilities to complete the anonymous questionnaires. The return rate of the questionnaire was 88.75%. The validated instruments of Hershenson's (1981) and Schaefer and Moos (1993) were adopted to measure work stressors and work adjustment, respectively. A forward-backward translation process was used in this study.</p> <p>Results</p> <p>Indonesian foreign nurse aides respect their work, and are better workers than Vietnamese and Filipino nurse aids in many respects, which shows how the nationality of the foreign nurse aides might affect work adjustment. The stress created from patient care tasks influenced the foreign nurse aides' personal relationships at work and also affected their attitude when they performed their tasks. In addition, pressure from their supervisors might have affected their work skills, work habits, personal relationships, self-concepts or work attitudes. Moreover, a heavy workload and improper scheduling might have affected the personal relationships and work attitudes of the foreign nurse aides. It was found that work stressors had a significant correlation with work adjustment.</p> <p>Conclusions</p> <p>The results of the present study indicate that training programs are important factors for work adjustment among foreign nurse aides. Furthermore, celebration and leisure activities could be provided to release them from work stressors. More effort should be put into improving the working environment, namely providing a more supportive and enriching atmosphere. Based on these findings, we have a better understanding of how to assist foreign nurse aides in the future.</p

    Attitudes to in vitro meat:A survey of potential consumers in the United States

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    Positivity towards meat consumption remains strong, despite evidence of negative environmental and ethical outcomes. Although awareness of these repercussions is rising, there is still public resistance to removing meat from our diets. One potential method to alleviate these effects is to produce in vitro meat: meat grown in a laboratory that does not carry the same environmental or ethical concerns. However, there is limited research examining public attitudes towards in vitro meat, thus we know little about the capacity for it be accepted by consumers. This study aimed to examine perceptions of in vitro meat and identify potential barriers that might prevent engagement. Through conducting an online survey with US participants, we identified that although most respondents were willing to try in vitro meat, only one third were definitely or probably willing to eat in vitro meat regularly or as a replacement for farmed meat. Men were more receptive to it than women, as were politically liberal respondents compared with conservative ones. Vegetarians and vegans were more likely to perceive benefits compared to farmed meat, but they were less likely to want to try it than meat eaters. The main concerns were an anticipated high price, limited taste and appeal and a concern that the product was unnatural. It is concluded that people in the USA are likely to try in vitro meat, but few believed that it would replace farmed meat in their diet

    Radiotherapy in the treatment of Graves ophthalmopathy—to do it or not?

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    To the objective of this study is to evaluate the role and toxicity of radiotherapy in the treatment of Graves ophthalmopathy. In the years 2000–2003, 121 patients with malignant exophthalmos were treated with radiotherapy of the retrobulbar area to the total dose of 20 Gy in ten fractions with a 6 MeV photon beam. The treatment was performed by the team of the Clinic of Oncology of the Jagiellonian University Medical College in Cracow. The radiotherapy was preceded by intravenous steroid therapy: methylprednisolone acetate administered at the dose of 2 g/week for four consecutive weeks. The highest efficacy, expressed as improvement of all ocular symptoms, was observed for the combined treatment. Female and non-diabetic patients responded positively to the combined treatment. Radiotherapy combined with steroid therapy in the treatment of Graves ophthalmopathy seems to be an effective treatment for strictly defined indications. In the treatment of Graves–Basedow disease, radiotherapy is a well-tolerated treatment modality. Diabetes is a factor that worsens prognosis in Graves ophthalmopathy and female sex is a favourable factor for this condition
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