290 research outputs found
Old open clusters in the inner Galaxy: FSR1744, FSR89 and FSR31
We establish the nature and derive fundamental and structural parameters of
the recently catalogued objects FSR1744, FSR89 and FSR31. This work intends to
provide clues to constrain the Galactic tidal disruption efficiency, improve
statistics of the open cluster parameter space, and better define their
age-distribution function inside the Solar circle. Properties of the objects
are investigated by means of 2MASS colour-magnitude diagrams and stellar radial
density profiles built with field star decontaminated photometry.
Diagnostic-diagrams for structural parameters are used to help disentangle
dynamical from high-background effects affecting such centrally projected open
clusters. FSR1744, FSR89 and FSR31 are Gyr-class OCs located at Galactocentric
distances 4.0 - 5.6kpc. Compared to nearby OCs, they have small core and
limiting radii. With respect to the small number of OCs observed in the inner
Galaxy, the emerging scenario in the near-infrared favours disruption driven by
dynamical evolution rather than observational limitations associated with
absorption and/or high background levels. Internally, the main processes
associated with the dynamical evolution are, e.g. mass loss by stellar
evolution, mass segregation and evaporation. Externally they are, e.g. tidal
stress from the disk and bulge, and interactions with giant molecular clouds.
FSR1744, FSR89 and FSR31 have structural parameters consistent with their
Galactocentric distances, in the sense that tidally induced effects may have
accelerated the dynamical evolution.Comment: 12 pages and 13 figs; A&A, accepted, July 9, 200
Joint 3D modelling of the polarized Galactic synchrotron and thermal dust foreground diffuse emission
We present for the first time a coherent model of the polarized Galactic
synchrotron and thermal dust emissions which are the main diffuse foreground
for the measurement of the polarized power spectra of the CMB fluctuations with
the Planck satellite mission. We produce 3D models of the Galactic magnetic
field including regular and turbulent components, and of the distribution of
matter in the Galaxy, relativistic electrons and dust grains. By integrating
along the line of sight we construct maps of the polarized Galactic synchrotron
and thermal dust emission for each of these models and compare them to
currently available data. We consider the 408 MHz all-sky continuum survey, the
23 GHz band of the Wilkinson Microwave Anisotropy Probe and the 353 GHz
Archeops data.}{The best-fit parameters obtained are consistent with previous
estimates in the literature based only on synchrotron emission and pulsar
rotation measurements. They allows us to reproduce the large scale structures
observed on the data. Poorly understood local Galactic structures and
turbulence make difficult an accurate reconstruction of the observations in the
Galactic plane. Finally, using the best-fit model we are able to estimate the
expected polarized foreground contamination at the Planck frequency bands. For
the CMB bands, 70, 100, 143 and 217 GHz, at high Galactic latitudes although
the CMB signal dominates in general, a significant foreground contribution is
expected at large angular scales. In particular, this contribution will
dominate the CMB signal for the B modes expected from realistic models of a
background of primordial gravitational waves
Top-heavy integrated galactic stellar initial mass functions (IGIMFs) in starbursts
Star formation rates (SFR) larger than 1000 Msun/ yr are observed in extreme
star bursts. This leads to the formation of star clusters with masses > 10^6
Msun in which crowding of the pre-stellar cores may lead to a change of the
stellar initial mass function (IMF). Indeed, the large mass-to-light ratios of
ultra-compact dwarf galaxies and recent results on globular clusters suggest
the IMF to become top-heavy with increasing star-forming density. We explore
the implications of top-heavy IMFs in these very massive and compact systems
for the integrated galactic initial mass function (IGIMF), which is the
galaxy-wide IMF, in dependence of the star-formation rate of galaxies. The
resulting IGIMFs can have slopes, alpha_3, for stars more massive than about 1
Msun between 1.5 and the Salpeter slope of 2.3 for an embedded cluster mass
function (ECMF) slope (beta) of 2.0, but only if the ECMF has no low-mass
clusters in galaxies with major starbursts. Alternatively, beta would have to
decrease with increasing SFR >10 Msun/ yr such that galaxies with major
starbursts have a top-heavy ECMF. The resulting IGIMFs are within the range of
observationally deduced IMF variations with redshift.Comment: Accepted for publication in MNRAS, reference adde
Patient-centric trials for therapeutic development in precision oncology
An enhanced understanding of the molecular pathology of disease gained from genomic studies is facilitating the development of treatments that target discrete molecular subclasses of tumours. Considerable associated challenges include how to advance and implement targeted drug-development strategies. Precision medicine centres on delivering the most appropriate therapy to a patient on the basis of clinical and molecular features of their disease. The development of therapeutic agents that target molecular mechanisms is driving innovation in clinical-trial strategies. Although progress has been made, modifications to existing core paradigms in oncology drug development will be required to realize fully the promise of precision medicine
Medication administration errors for older people in long-term residential care
Background
Older people in long-term residential care are at increased risk of medication errors. The purpose of this study was to evaluate a computerised barcode medication management system designed to improve drug administrations in residential and nursing homes, including comparison of error rates and staff awareness in both settings.
Methods
All medication administrations were recorded prospectively for 345 older residents in thirteen care homes during a 3-month period using the computerised system. Staff were surveyed to identify their awareness of administration errors prior to system introduction. Overall, 188,249 attempts to administer medication were analysed to determine the prevalence of potential medication administration errors (MAEs). Error classifications included attempts to administer medication at the wrong time, to the wrong person or discontinued medication. Analysis compared data at residential and nursing home level and care and nursing staff groups.
Results
Typically each resident was exposed to 206 medication administration episodes every month and received nine different drugs. Administration episodes were more numerous (p < 0.01) in nursing homes (226.7 per resident) than in residential homes (198.7). Prior to technology introduction, only 12% of staff administering drugs reported they were aware of administration errors being averted in their care home. Following technology introduction, 2,289 potential MAEs were recorded over three months. The most common MAE was attempting to give medication at the wrong time. On average each resident was exposed to 6.6 potential errors. In total, 90% of residents were exposed to at least one MAE with over half (52%) exposed to serious errors such as attempts to give medication to the wrong resident. MAEs rates were significantly lower (p < 0.01) in residential homes than nursing homes. The level of non-compliance with system alerts was low in both settings (0.075% of administrations) demonstrating virtually complete error avoidance.
Conclusion
Potentially inappropriate administration of medication is a serious problem in long-term residential care. A computerised barcode system can accurately and automatically detect inappropriate attempts to administer drugs to residents. This tool can reliably be used by care staff as well as nurses to improve quality of care and patient safety
Calcium isotope (δ<sup>44/40</sup>Ca ) variations of Neogene planktonic foraminifera
Measurements of the calcium isotopic composition (δ44/40Ca) of planktonic foraminifera from the western equatorial Pacific and the Indian sector of the Southern Ocean show variations of about 0.6‰ over the past 24 Myr. The stacked δ44/40Ca record of Globigerinoides trilobus and Globigerina bulloides indicates a minimum in δ44/40Casw (seawater calcium) at 15 to 16 Ma and a subsequent general increase toward the present, interrupted by a second minimum at 3 to 5 Ma. Applying a coupled calcium/carbon cycle model, we find two scenarios that can explain a large portion of the observed δ44/40Casw variations. In both cases, variations in the Ca input flux to the ocean without proportional changes in the carbonate flux are invoked. The first scenario increases the riverine calcium input to the ocean without a proportional increase of the carbonate flux. The second scenario generates an additional calcium flux from the exchange of Ca by Mg during dolomitization. In both cases the calcium flux variations lead to drastic changes in the seawater Ca concentrations on million year timescales. Our δ44/40Casw record therefore indicates that the global calcium cycle may be much more dynamic than previously assumed
Constraining calcium isotope fractionation (δ44/40Ca) in modern and fossil scleractinian coral skeleton
The present study investigates the influence of environmental (temperature, salinity) and biological (growth rate, inter-generic variations) parameters on calcium isotope fractionation (δ44/40Ca) in scleractinian coral skeleton to better constrain this record. Previous studies focused on the δ44/40Ca record in different marine organisms to reconstruct seawater composition or temperature, but only few studies investigated corals.
This study presents measurements performed on modern corals from natural environments (from the Maldives for modern and from Tahiti for fossil corals) as well as from laboratory cultures (Centre Scientifique de Monaco). Measurements on Porites sp., Acropora sp., Montipora verrucosa and Stylophora pistillata allow constraining inter-generic variability.
Our results show that the fractionation of δ44/40Ca ranges from 0.6 to 0.1‰, independent of the genus or the environmental conditions. No significant relationship between the rate of calcification and δ44/40Ca was found. The weak temperature dependence reported in earlier studies is most probably not the only parameter that is responsible for the fractionation. Indeed, sub-seasonal temperature variations reconstructed by δ18O and Sr/Ca ratio using a multi-proxy approach, are not mirrored in the coral's δ44/40Ca variations. The intergeneric variability and intrageneric variability among the studied samples are weak except for S. pistillata, which shows calcium isotopic values increasing with salinity. The variability between samples cultured at a salinity of 40 is higher than those cultured at a salinity of 36 for this species.
The present study reveals a strong biological control of the skeletal calcium isotope composition by the polyp and a weak influence of environmental factors, specifically temperature and salinity (except for S. pistillata). Vital effects have to be investigated in situ to better constrain their influence on the calcium isotopic signal. If vital effects could be extracted from the isotopic signal, the calcium isotopic composition of coral skeletons could provide reliable information on the calcium composition and budget in ocean.
Highlights
► Corals cultured in aquaria or from natural environment show the same Ca isotopic composition. ► δ44/40Ca of coral skeleton is independent of depositional setting environment. ► Strong influence of vital effects on coral skeleton δ44/40Ca composition and calcification mechanism
High Energy Activity of the Super-Massive Black Hole at the Galactic Center
The centre of our galaxy hosts the nearest super-massive black hole to the
solar system, identified to the compact radio source Sgr A*. High energy
experiments have tried in the past to detect the X/gamma-ray emission expected
from the accretion of the surrounding material into this super-massive black
hole. Only recently however, thanks to the new generation of telescopes, it has
been possible to reveal high energy radiation associated with Sgr A* or its
close environment. I will review and discuss in particular the results on the
Sgr A* X-ray flares discovered with Chandra and XMM-Newton, on the central soft
gamma-ray source detected with INTEGRAL and on the galactic centre TeV emission
revealed by HESS.Comment: 10 pages, 6 figures. Published in Comptes Rendus Physique, Volume 8,
Issue 1, January 2007, Pages 35-44, "Observation of black holes and extreme
gravitational events", Academie des Sciences, Elsevier Science. Available
online 2 February 200
Circumstellar disks and planets. Science cases for next-generation optical/infrared long-baseline interferometers
We present a review of the interplay between the evolution of circumstellar
disks and the formation of planets, both from the perspective of theoretical
models and dedicated observations. Based on this, we identify and discuss
fundamental questions concerning the formation and evolution of circumstellar
disks and planets which can be addressed in the near future with optical and
infrared long-baseline interferometers. Furthermore, the importance of
complementary observations with long-baseline (sub)millimeter interferometers
and high-sensitivity infrared observatories is outlined.Comment: 83 pages; Accepted for publication in "Astronomy and Astrophysics
Review"; The final publication is available at http://www.springerlink.co
Antibacterial and dermal toxicological profiles of ethyl acetate extract from Crassocephalum bauchiense (Hutch.) Milne-Redh (Asteraceae)
<p>Abstract</p> <p>Background</p> <p>The emergence in recent years of numerous resistant strains of pathogenic bacteria to a range of formerly efficient antibiotics constitutes a serious threat to public health. <it>Crassocephalum bauchiense</it>, a medicinal herb found in the West Region of Cameroon is used to treat gastrointestinal infections as well as liver disorders. The ethyl acetate extract from the leaves of <it>C. bauchiense </it>was evaluated for its antibacterial activity as well as acute and sub-acute toxicities.</p> <p>Methods</p> <p>The plant extract was prepared by maceration in ethyl acetate. Its phytochemical screening was done by standard methods. The broth microdilution method was used to evaluate the <it>in vitro </it>antibacterial activity. The <it>in vivo </it>antibacterial activity of a gel formulation (0.05, 1 and 2% w/v) of this extract was evaluated using a <it>Staphylococcus aureus</it>-induced dermatitis in a murine model. Selected haematological and biochemical parameters were used to evaluate the dermal sub-acute toxicity of the extract in rats.</p> <p>Results</p> <p>Phytochemical screening of the <it>C. bauchiense </it>extract revealed the presence of alkaloids, phenols, tannins and sterols. <it>In vitro </it>antibacterial activities were observed against all the tested microorganisms (MIC = 0.04-6.25 mg/ml). Formulated extract-gel (2% w/v) and gentamycin (reference drug) eradicated the microbial infection after five days of treatment. A single dermal dose of this extract up to 32 g/kg body weight (bw) did not produce any visible sign of toxicity. Also, daily dermal application of the <it>C. bauchiense </it>extract gel formulation for 28 days did not show any negative effect, instead some biochemical parameters such as alanine aminotransferase (ALT and AST), low density lipoprotein (LDL), high density lipoprotein (HDL) and triglycerides were significantly (p < 0.05) affected positively.</p> <p>Conclusion</p> <p>These results indicate that the <it>C. bauchiense </it>ethyl acetate extract can be used safely for the treatment of some bacterial infections.</p
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