88 research outputs found
New abundance measurements in UKS 1927-177, a very metal-poor galaxy in the Local Group
We present new results from optical spectroscopy of the brightest Hii region
in the dwarf irregular galaxy UKS 1927-177 in Sagittarius (SagDIG). From high
signal-to-noise spectra, reddening-corrected line flux ratios have been
measured with typical uncertainties of a few percent, from which the oxygen
abundance is rediscussed, and new abundance estimates are derived for N and Ne.
The O abundance in SagDIG, estimated with the empirical abundance indicator R23
and other methods, is in the range 12+log(O/H)=7.26 to 7.50. The fact that
SagDIG is ~10 times closer than IZw18 makes it an ideal target to test the
hypothesis of the existence of young galaxies in the present-day universe.
Indeed, stellar photometry suggests that this galaxy may harbor a stellar
population older than a few Gyr, and possibly an old stellar component as well.
The case of SagDIG therefore supports the view that very low chemical
abundances can be maintained throughout the life of a dwarf stellar system,
even in the presence of multiple star formation episodes.Comment: 6 pages, 3 figures, accepted for publication in A&A, main journa
A novel design process for selection of attributes for inclusion in discrete choice experiments:Case study exploring variation in clinical decision-making about thrombolysis in the treatment of acute ischaemic stroke
On-line structured prioritisation exercise (SPE). Full survey used to collect data. (DOCX 42Â kb
Measurement of the production cross-sections of in p-C and -C interactions at 12 GeV/c
The results of the measurements of the double-differential production
cross-sections of pions in p-C and -C interactions using the forward
spectrometer of the HARP experiment are presented. The incident particles are
12 GeV/c protons and charged pions directed onto a carbon target with a
thickness of 5% of a nuclear interaction length. For p-C interactions the
analysis is performed using 100035 reconstructed secondary tracks, while the
corresponding numbers of tracks for -C and -C analyses are 106534
and 10122 respectively. Cross-section results are presented in the kinematic
range 0.5 GeV/c 8 GeV/c and 30 mrad 240
mrad in the laboratory frame. The measured cross-sections have a direct impact
on the precise calculation of atmospheric neutrino fluxes and on the improved
reliability of extensive air shower simulations by reducing the uncertainties
of hadronic interaction models in the low energy range.Comment: accepted for publication in Astroparticle Physic
Key stakeholder perceptions about consent to participate in acute illness research: a rapid, systematic review to inform epi/pandemic research preparedness
Background
A rigorous research response is required to inform clinical and public health decision-making during an epi/pandemic. However, the ethical conduct of such research, which often involves critically ill patients, may be complicated by the diminished capacity to consent and an imperative to initiate trial therapies within short time frames. Alternative approaches to taking prospective informed consent may therefore be used. We aimed to rapidly review evidence on key stakeholder (patients, their proxy decision-makers, clinicians and regulators) views concerning the acceptability of various approaches for obtaining consent relevant to pandemic-related acute illness research.
Methods
We conducted a rapid evidence review, using the Internet, database and hand-searching for English language empirical publications from 1996 to 2014 on stakeholder opinions of consent models (prospective informed, third-party, deferred, or waived) used in acute illness research. We excluded research on consent to treatment, screening, or other such procedures, non-emergency research and secondary studies. Papers were categorised, and data summarised using narrative synthesis.
Results
We screened 689 citations, reviewed 104 full-text articles and included 52. Just one paper related specifically to pandemic research. In other emergency research contexts potential research participants, clinicians and research staff found third-party, deferred, and waived consent to be acceptable as a means to feasibly conduct such research. Acceptability to potential participants was motivated by altruism, trust in the medical community, and perceived value in medical research and decreased as the perceived risks associated with participation increased. Discrepancies were observed in the acceptability of the concept and application or experience of alternative consent models. Patients accepted clinicians acting as proxy-decision makers, with preference for two decision makers as invasiveness of interventions increased. Research regulators were more cautious when approving studies conducted with alternative consent models; however, their views were generally under-represented.
Conclusions
Third-party, deferred, and waived consent models are broadly acceptable to potential participants, clinicians and/or researchers for emergency research. Further consultation with key stakeholders, particularly with regulators, and studies focused specifically on epi/pandemic research, are required. We highlight gaps and recommendations to inform set-up and protocol development for pandemic research and institutional review board processes
Effect of the maceration time on chemical composition of extracts of Brazilian propolis
It is believed that longer maceration times change significantly the ethanolic extract composition of propolis, improving its pharmacological, nutritional and antimicrobial properties. To probe whether such superior composition is indeed obtained, 10 samples of propolis from several regions in Brazil and one sample from North America were left to macerate in 70% ethanol for periods between 20 days and one year. The resultant extracts were evaluated in terms of the yield of extracted material and also analyzed by electrospray ionization mass spectrometry (ESI-MS) fingerprinting. A small increase in the yield of the extracted material over the period analyzed was observed. ESI-MS fingerprints indicate qualitatively the same composition but with a greater incidence of the high-mass components after six months. The extracts of one sample of green Brazilian propolis were also quantified using both gas chromatography mass spectrometry and high performance liquid chromatography. No new components were identified after longer maceration times and the changes in the relative concentrations of the identified components were in line with the results of the yield and ESI-MS fingerprints. Therefore, prolonged extraction periods do not necessarily result in richer propolis extracts.45313714
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