3,503 research outputs found
New results in rho^0 meson physics
We compare the predictions of a range of existing models based on the Vector
Meson Dominance hypothesis with data on e^+ e^- -> pi^+ pi^$ and e^+ e^- ->
mu^+ mu^- cross-sections and the phase and near-threshold behavior of the
timelike pion form factor, with the aim of determining which (if any) of these
models is capable of providing an accurate representation of the full range of
experimental data. We find that, of the models considered, only that proposed
by Bando et al. is able to consistently account for all information, provided
one allows its parameter "a" to vary from the usual value of 2 to 2.4. Our fit
with this model gives a point-like coupling (gamma pi^+ \pi^-) of magnitude ~
-e/6, while the common formulation of VMD excludes such a term. The resulting
values for the rho mass and pi^+ pi^- and e^+e^- partial widths as well as the
branching ratio for the decay omega -> pi^+ pi^- obtained within the context of
this model are consistent with previous results.Comment: 34 pages with 7 figures. Published version also available at
http://link.springer.de/link/service/journals/10052/tocs/t8002002.ht
Electrical characterization of the soft breakdown failure mode in MgO layers
The soft breakdown (SBD) failure mode in 20 nm thick MgO dielectric layers grown on Si substrates was investigated. We show that during a constant voltage stress, charge trapping and progressive breakdown coexist, and that the degradation dynamics is captured by a power-law time dependence. We also show that the SBD current-voltage (I-V) characteristics follow the power-law model I = aVb typical of this conduction mechanism but in a wider voltage window than the one reported in the past for SiO2. The relationship between the magnitude of the current and the normalized differential conductance was analyzed
UV Bright Globular Clusters in M87: More Evidence for Super-helium-rich Stellar Populations?
We study the UV and optical properties of 38 massive GCs in M87, imaged using
the HST/STIS and WFPC2 instruments. The majority of these GCs appear extremely
bright in the FUV - roughly a magnitude brighter than their Galactic
counterparts with similar metallicities. The observed FUV flux is several times
larger than predictions of canonical old stellar population models. These
canonical models, which assume a fiducial helium enrichment parameter, dY/dZ=2,
are able to reproduce the observed FUV fluxes only if ages are 3--5 Gyr larger
than the WMAP age of the Universe, although the same models fit the UV
photometry of Galactic and M31 GCs for ages less than the WMAP age. A similar
discrepancy is found between the mass-weighted and UV-luminosity weighted ages
of the massive Galactic GC omega Cen, whose CMD (including peculiar features on
its well-populated horizontal branch) can be accurately reproduced by invoking
a small super-He-rich (dY/dZ ~ 90) stellar component. By comparison to omega
Cen, we propose that the majority of M87 GCs in our sample contain strong
signatures of similarly minor super-He-rich sub-components. Although we cannot
prove or disprove the extreme helium scenario at the moment, we show that the
same phenomenon that causes the extended horizontal branch of omega Cen
explains the UV brightness of our sample. If this is indeed due to the extreme
helium, this study would be the first to find its signatures in extragalactic
objects.Comment: 19 pages, 10 figures, accepted for publication in MNRA
Prognostic factors of depression and depressive symptoms after hip fracture surgery: systematic review.
BACKGROUND: Patients with hip fracture and depression are less likely to recover functional ability. This review sought to identify prognostic factors of depression or depressive symptoms up to 1 year after hip fracture surgery in adults. This review also sought to describe proposed underlying mechanisms for their association with depression or depressive symptoms. METHODS: We searched for published (MEDLINE, Embase, PsychInfo, CINAHL and Web of Science Core Collection) and unpublished (OpenGrey, Greynet, BASE, conference proceedings) studies. We did not impose any date, geographical, or language limitations. Screening (Covidence), extraction (Checklist for critical Appraisal and data extraction for systematic Reviews of prediction Modelling Studies, adapted for use with prognostic factors studies Checklist), and quality appraisal (Quality in Prognosis Studies tool) were completed in duplicate. Results were summarised narratively. RESULTS: In total, 37 prognostic factors were identified from 12 studies included in this review. The quality of the underlying evidence was poor, with all studies at high risk of bias in at least one domain. Most factors did not have a proposed mechanism for the association. Where factors were investigated by more than one study, the evidence was often conflicting. CONCLUSION: Due to conflicting and low quality of available evidence it is not possible to make clinical recommendations based on factors prognostic of depression or depressive symptoms after hip fracture. Further high-quality research investigating prognostic factors is warranted to inform future intervention and/or stratified approaches to care after hip fracture. TRIAL REGISTRATION: Prospero registration: CRD42019138690
Patterns of care and emergency presentations for people with non-small cell lung cancer in New South Wales, Australia: A population-based study
Introduction Little is known about population-wide emergency presentations and patterns of care for people diagnosed with non-small cell lung cancer (NSCLC) in Australia. We examined patients’ characteristics associated with presenting to an emergency department around the time of diagnosis (“emergency presenters”), and receiving anti-cancer treatment within 12 months of diagnosis. Materials and Methods Participants in the 45 and Up Study who were newly diagnosed with NSCLC during 2006–2010 were included. We used linked data from population-wide health databases including Medicare and pharmaceutical claims, inpatient hospitalisations and emergency department presentations to follow participants to June 2014. Patients’ characteristics associated with being an emergency presenter and receiving any anti-cancer treatment were examined. Results A total of 647 NSCLC cases were included (58.6% male, median age 73 years). Emergency presenters (34.5% of cases) were more likely to have a high Charlson comorbidity index score, be an ex-smoker who had quit in the past 15 years and to be diagnosed with distant metastases. Almost all patients had visited their general practitioner ≥3 times in the 6 months prior to diagnosis. Nearly one-third (29.5%) of patients did not receive any anti-cancer treatment, however, there were no differences between emergency and non-emergency presenters in the likelihood of receiving treatment. Those less likely to be treated were older, had no private health insurance, and had unknown stage disease recorded. Conclusion Our results indicate the difficulties in diagnosing lung cancer at an early stage and inequities in NSCLC treatment. Future research should address opportunities to diagnose lung cancer earlier and to optimise treatment pathways
Movement as Medicine for Cardiovascular Disease Prevention: Pilot Feasibility Study of a Physical Activity Promotion Intervention for At-Risk Patients in Primary Care
High rates of loss of heterozygosity on chromosome 19p13 in human breast cancer
We have recently discovered that the nuclear matrix protein SAFB is an oestrogen receptor corepressor. Since it has become clear that many steroid receptor cofactors play important roles in breast tumorigenesis, we investigated whether SAFB could also be involved in breast cancer. To address this question, the gene locus was examined for structural alterations in breast cancer tissue. Laser capture microdissection was used for isolating DNA from paired primary breast tumour and normal tissue specimens, and the loss of heterozygosity (LOH) at chromosome 19p13.2–3 was determined by use of microsatellite markers. LOH was detected at the marker D19S216, which colocalizes with the SAFB locus, in specimens from 29 (78.4%) of 37 informative patients. The peak LOH rate occurred at D19S216 near the SAFB locus, with LOH frequencies ranging from 21.6% to 47.2% at other markers. The finding of a very high LOH rate at the marker D19S216 strongly indicates the presence of a breast tumour-suppressor gene locus. While preliminary findings of mutations in SAFB suggest that this indeed may be a promising candidate, other potential candidate genes are located at this locus. © 2001 Cancer Research Campaign http://www.bjcancer.co
Ultraviolet Imaging Observations of the cD Galaxy in Abell 1795: Further Evidence for Massive Star Formation in a Cooling Flow
We present images from the Ultraviolet Imaging Telescope of the Abell 1795
cluster of galaxies. We compare the cD galaxy morphology and photometry of
these data with those from existing archival and published data. The addition
of a far--UV color helps us to construct and test star formation model
scenarios for the sources of UV emission. Models of star formation with rates
in the range \sim5-20M_{\sun}yr indicate that the best fitting models
are those with continuous star formation or a recent ( Myr old) burst
superimposed on an old population. The presence of dust in the galaxy,
dramatically revealed by HST images complicates the interpretation of UV data.
However, we find that the broad--band UV/optical colors of this cD galaxy can
be reasonably matched by models using a Galactic form for the extinction law
with . We also briefly discuss other objects in the large UIT
field of view.Comment: To appear in the Astrophysical Journal. 14 AAS preprint style pages
plus 7 figure
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