1,824 research outputs found
Palaeoecological assessment of freshwaters in SACs and ASSIs in Northern Ireland
This is the final report to the Environment and Heritage Service (EHS) in Northern Ireland on the
‘Palaeoecological investigation of the past biological structure and function in Freshwaters in SACs
and ASSIs
An extragalactic supernebula confined by gravity
Little is known about the origins of the giant star clusters known as
globular clusters. How can hundreds of thousands of stars form simultaneously
in a volume only a few light years across the distance of the sun to its
nearest neighbor? Radiation pressure and winds from luminous young stars should
disperse the star-forming gas and disrupt the formation of the cluster.
Globular clusters in our Galaxy cannot provide answers; they are billions of
years old. Here we report the measurement of infrared hydrogen recombination
lines from a young, forming super star cluster in the dwarf galaxy, NGC 5253.
The lines arise in gas heated by a cluster of an estimated million stars, so
young that it is still enshrouded in gas and dust, hidden from optical view. We
verify that the cluster contains 4000-6000 massive, hot "O" stars. Our
discovery that the gases within the cluster are bound by gravity may explain
why these windy and luminous O stars have not yet blown away the gases to allow
the cluster to emerge from its birth cocoon. Young clusters in "starbursting"
galaxies in the local and distant universe may be similarly gravitationally
confined and cloaked from view.Comment: Letter to Natur
Estimating the number needed to treat from continuous outcomes in randomised controlled trials: methodological challenges and worked example using data from the UK Back Pain Exercise and Manipulation (BEAM) trial
Background
Reporting numbers needed to treat (NNT) improves interpretability of trial results. It is unusual that continuous outcomes are converted to numbers of individual responders to treatment (i.e., those who reach a particular threshold of change); and deteriorations prevented are only rarely considered. We consider how numbers needed to treat can be derived from continuous outcomes; illustrated with a worked example showing the methods and challenges.
Methods
We used data from the UK BEAM trial (n = 1, 334) of physical treatments for back pain; originally reported as showing, at best, small to moderate benefits. Participants were randomised to receive 'best care' in general practice, the comparator treatment, or one of three manual and/or exercise treatments: 'best care' plus manipulation, exercise, or manipulation followed by exercise. We used established consensus thresholds for improvement in Roland-Morris disability questionnaire scores at three and twelve months to derive NNTs for improvements and for benefits (improvements gained+deteriorations prevented).
Results
At three months, NNT estimates ranged from 5.1 (95% CI 3.4 to 10.7) to 9.0 (5.0 to 45.5) for exercise, 5.0 (3.4 to 9.8) to 5.4 (3.8 to 9.9) for manipulation, and 3.3 (2.5 to 4.9) to 4.8 (3.5 to 7.8) for manipulation followed by exercise. Corresponding between-group mean differences in the Roland-Morris disability questionnaire were 1.6 (0.8 to 2.3), 1.4 (0.6 to 2.1), and 1.9 (1.2 to 2.6) points.
Conclusion
In contrast to small mean differences originally reported, NNTs were small and could be attractive to clinicians, patients, and purchasers. NNTs can aid the interpretation of results of trials using continuous outcomes. Where possible, these should be reported alongside mean differences. Challenges remain in calculating NNTs for some continuous outcomes
Gitksan medicinal plants-cultural choice and efficacy
BACKGROUND: The use of plants for healing by any cultural group is integrally related to local concepts of the nature of disease, the nature of plants, and the world view of the culture. The physical and chemical properties of the plants themselves also bear on their selection by people for medicines, as does the array of plants available for people to choose from. I examine use of medicinal plants from a "biobehavioral" perspective to illuminate cultural selection of plants used for medicine by the Gitksan of northwestern British Columbia, Canada. METHODS: Consultant consensus, "intercultural consensus", independent use of the same plants by other cultural groups, and phytochemistry and bioassay results from the literature, were employed in analysis of probable empirical efficacy of plant uses. RESULTS: 70% of 37 Gitksan medicinal plants were used similarly by other cultures where direct diffusion is not known to have occurred; eleven plants, including the eight most frequently mentioned medicinal plants, also show active phytochemicals or bioassays indicating probable physiologically based therapeutic effects. CONCLUSION: Analysis of intercultural consensus revealed that the majority of cultures in the British Columbia region within the plant ranges use the same plants, or closely related species, in similar ways. The rigor of this analysis is effected by the lack of consistent data on all taxa of interest for all cultures within the region
Orbital Elements and Stellar Parameters of the Active Binary UX Arietis
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
Life story and narrative approaches in the study of family lives
The chapter examines life story and narrative approaches and their application in the study of family lives. It begins with a brief history of some key figures in biographical research followed by an examination of some of the distinctions between the two approaches. The second part of the chapter presents and discusses a case of a grandfather and son drawn from an intergenerational study of fatherhood. The study’s method (the biographic-narrative interpretive method) demonstrates change and continuity in family life by situating lives in historical context and examining the cultural transmissions that are accepted and resisted by the younger generation. The chapter discusses the benefits of paying attention to the narrative form of life stories. In these ways biographical and narrative approaches produce a multi-layered analysis
Health and the Running Body: Notes from an Ethnography
This article aims to develop one of the major themes from an ethnographic study of the culture of distance running – the desire for health and fitness. Research was undertaken over a 2-year period using a variety of flexible qualitative data sources, most notably observation and in-depth interviews. The body, especially the ‘running body’, is seen by participants in this study as a source of health and well-being and affirmation of their identity. The results highlight the various contradictions and tensions that emerged whilst exploring the behaviour of distance runners in their desire to achieve a healthy body and mind
Re-evaluation of the diagnosis of porphyria cutanea tarda in Admiral Sir Francis Beaufort
OBJECTIVES: Two biographies of Admiral Francis Beaufort (1774-1857) have stated that, aged 20-25 years, he suffered from porphyria cutanea tarda (PCT) that was 'cured' following severe blood loss during a naval skirmish. We have examined the evidence concerning the nature of his skin disease. DESIGN: Primary records, most notably Beaufort's correspondence with his family, his journals and his father's diaries were sought out and analysed. SETTING: This case report is discussed in the context of 18th-century naval medicine and concepts and treatment of skin disease. RESULTS: The description of his lesions, their age of onset, their progression and response to treatment, particularly topical tar and associated features are quite inconsistent with a diagnosis of PCT. His mother, Mary Waller Beaufort (1739-1821), consulted Dr Robert Darwin in 1803 about a painful skin disease affecting her legs. Detailed description of the lesions and a contemporary diagnosis are not available but possible diagnoses include chronic psoriasis and stasis eczema. CONCLUSIONS: A more tenable diagnosis is that Francis Beaufort had chronic plaque psoriasis remitted by bed rest and convalescence in the sunny Mediterranean climate with cessation of alcohol consumption and improved nutrition as well as topical and oral medications
Multiplicity of Galactic Cepheids from long-baseline interferometry. I. CHARA/MIRC detection of the companion of V1334 Cygni
This is the final version of the article. Available from the publisher via the DOI in this record.Context. More than 60% of Cepheids are in binary or multiple systems. Studying such systems could lead to a better understanding
of the age and evolution of Cepheids. These are also useful tools to estimate the mass of Cepheids, and constrain theoretical models
of their pulsation and evolution.
Aims. We aim at determining the masses of Cepheids in binary systems, as well as their geometric distances and the flux contribution
of the companions. The combination of interferometry with spectroscopy will offer a unique and independent estimate of the Cepheid
masses.
Methods. Using long-baseline interferometry at visible and infrared wavelengths, it is possible to spatially resolve binary systems
containing a Cepheid down to milliarcsecond separations. Based on the resulting visual orbit and radial velocities, we can then derive
the fundamental parameters of these systems, particularly the masses of the components and the geometric distance. We therefore
performed interferometric observations of the first-overtone mode Cepheid V1334 Cyg with the CHARA/MIRC combiner.
Results. We report the first detection of a Cepheid companion using long-baseline interferometry. We detect the signature of a
companion orbiting V1334 Cyg at two epochs. We measure a flux ratio between the companion and the Cepheid f = 3.10 ± 0.08%,
giving an apparent magnitude mH = 8.47 ± 0.15 mag. The combination of interferometric and spectroscopic data have enabled
the unique determination of the orbital elements. P = 1938.6 ± 1.2 days, Tp = 2 443 616.1 ± 7.3, a = 8.54 ± 0.51 mas, i =
124.7 ± 1.8
◦
, e = 0.190 ± 0.013, ω = 228.7 ± 1.6
◦
, and Ω = 206.3 ± 9.4
◦
. We derive a minimal distance d ∼ 691 pc, a minimum
mass for both stars of 3.6 M , with a spectral type earlier than B5.5V for the companion star. Our measured flux ratio suggests that
radial velocity detection of the companion using spectroscopy is within reach, and would provide an orbital parallax and model-free
massesThe authors would like to thank the CHARA Array and
Mount Wilson Observatory staff for their support. Research conducted at the
CHARA Array is funded by the National Science Foundation through NSF
grant AST-0908253, by Georgia State University, the W. M. Keck Foundation,
the Packard Foundation, and the NASA Exoplanet Science Institute. J.D.M.
acknowledges funding from the NSF grants AST-0707927 and AST-0807577.
W.G. and G.P. gratefully acknowledge financial support for this work from
the BASAL Centro de Astrofísica y Tecnologías Afines (CATA) PFB-06/2007.
Support from the Polish National Science Centre grant MAESTRO and the
Polish Ministry of Science grant Ideas Plus (awarded to G. P.) is also acknowledge.
This research received the support of PHASE, the high angular
resolution partnership between ONERA, Observatoire de Paris, CNRS,
and University Denis Diderot Paris 7. A.G. acknowledges support from
FONDECYT grant 3130361. LSz has been supported by the ESTEC Contract
No.4000106398/12/NL/KML. This work made use of the SIMBAD and VIZIER
astrophysical database from CDS, Strasbourg, France and the bibliographic informations
from the NASA Astrophysics Data System. This research has made
use of the Jean-Marie Mariotti Center LITpro service, co-developed by CRAL,
LAOG and FIZEAU, and SearchCal service, co-developed by FIZEAU and
LAOG/IPAG, and of CDS Astronomical Databases SIMBAD and VIZIER
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