2,519 research outputs found
Absolute magnitudes for late-type dwarf stars for Sloan photometry
We present a new formula for absolute magnitude determination for late-type
dwarf stars as a function of (g-r) and (r-i) for Sloan photometry. The absolute
magnitudes estimated by this approach are brighter than those estimated by
colour-magnitude diagrams, and they reduce the luminosity function rather close
to the luminosity function of Hipparcos.Comment: 11 pages, 9 figures and 5 tables, accepted for publication in A
Adult xanthogranuloma with LMNA-NTRK1 gene fusion - a possible driver of proliferation
The stellar metallicity distribution in intermediate latitude fields with BATC and SDSS data
Based on the Beijing-Arizona-Taiwan-Connecticut (BATC) and Sloan Digital Sky
Survey (SDSS) photometric data, we adopt SEDs fitting Method to evaluate the
metallicity distribution for \sim40,000 main-sequence stars in the Galaxy.
According to the derived photometric metallicities of these sample stars, we
find that the metallicity distribution shift from metal-rich to metal-poor with
the increase of distance from the Galactic center. The mean metallicity is
about of 1.5 \pm 0.2dex in the outer halo and 1.3 \pm 0.1 dex in the inner
halo. The mean metallicity smoothly decreases from -0.4 to -0.8 in interval 0 <
r \leq 5 kpc. The fluctuation in the mean metallicity with Galactic longitude
can be found in interval 4 < r \leq 8 kpc. There is a vertical abundance
gradients d[Fe/H]/dz\sim -0.21 \pm 0.05 dex kpc-1 for the thin disk (z \leq 2
kpc). At distance 2 < z \leq 5 kpc, where the thick disk stars are dominated,
the gradients are about of -0.16 \pm0.06 dex kpc-1, it can be interpreted as a
mixture of stellar population with different mean metallicities at all z
levels. The vertical metallicity gradient is - 0.05 \pm0.04 dex kpc-1 for the
halo (z > 5 kpc). So there is little or no metallicity gradient in the halo
Colossal magnetocapacitance and scale-invariant dielectric response in phase-separated manganites
Thin films of strongly-correlated electron materials (SCEM) are often grown
epitaxially on planar substrates and typically have anisotropic properties that
are usually not captured by edge-mounted four-terminal electrical measurements,
which are primarily sensitive to in-plane conduction paths. Accordingly, the
correlated interactions in the out-of-plane (perpendicular) direction cannot be
measured but only inferred. We address this shortcoming and show here an
experimental technique in which the SCEM under study, in our case a 600
Angstrom-thick (La1-yPry)0.67Ca0.33MnO3 (LPCMO) film, serves as the base
electrode in a metal-insulator-metal (MIM) trilayer capacitor structure. This
unconventional arrangement allows for simultaneous determination of colossal
magnetoresistance (CMR) associated with dc transport parallel to the film
substrate and colossal magnetocapacitance (CMC) associated with ac transport in
the perpendicular direction. We distinguish two distinct strain-related
direction-dependent insulator-metal (IM) transitions and use Cole-Cole plots to
establish a heretofore unobserved collapse of the dielectric response onto a
universal scale-invariant power-law dependence over a large range of frequency,
temperature and magnetic field.Comment: 32 pages, 4 figures, Supplementary section included, Submitted to
Nature Physic
Coliform pyosalpinx as a rare complication of appendicectomy: a case report and review of the literature on best practice
<p>Abstract</p> <p>Introduction</p> <p>Coliform pyosalpinx is a rare entity. We report a case that occurred three months after appendicectomy for gangrenous appendicitis. There follows a literature review on best practice for the treatment of pyosalpinx.</p> <p>Case presentation</p> <p>A seventeen year old girl presented with an acute abdomen three months after an appendicectomy for gangrenous appendicitis. Intraoperative findings were bilateral pyosalpinx treated by aspiration, saline and Betadine irrigation and intravenous antibiotics.</p> <p>Conclusion</p> <p>Microbiological analysis of the pus revealed <it>Escherichia coli </it>and anaerobes. Chlamydia and Candida were not isolated. This is the first known reported case of Coliform Pyosalpinx following appendicectomy. The best treatment does not necessarily involve salpingectomy especially in women of reproductive age where fertility may become compromised.</p
Functional neurological disorders in Parkinson disease
OBJECTIVE: To ascertain demographic and clinical features of Parkinson disease (PD) associated with functional neurological features.
METHODS: A standardised form was used to extract data from electronic records of 53 PD patients with associated functional neurological disorders (PD-FND) across eight movement disorders centres in the USA, Canada and Europe. These subjects were matched for age, gender and disease duration to PD patients without functional features (PD-only). Logistic regression analysis was used to compare both groups after adjusting for clustering effect.
RESULTS: Functional symptoms preceded or co-occurred with PD onset in 34% of cases, nearly always in the most affected body side. Compared with PD-only subjects, PD-FND were predominantly female (68%), had longer delay to PD diagnosis, greater prevalence of dyskinesia (42% vs 18%; P=0.023), worse depression and anxiety (P=0.033 and 0.025, respectively), higher levodopa-equivalent daily dose (972±701 vs 741±559 mg; P=0.029) and lower motor severity (P=0.019). These patients also exhibited greater healthcare resource utilisation, higher use of [(123)I]FP-CIT SPECT and were more likely to have had a pre-existing psychiatric disorder (P=0.008) and family history of PD (P=0.036).
CONCLUSIONS: A subtype of PD with functional neurological features is familial in one-fourth of cases and associated with more psychiatric than motor disability and greater use of diagnostic and healthcare resources than those without functional features. Functional manifestations may be prodromal to PD in one-third of patients
A population of luminous accreting black holes with hidden mergers
Major galaxy mergers are thought to play an important part in fuelling the
growth of supermassive black holes. However, observational support for this
hypothesis is mixed, with some studies showing a correlation between merging
galaxies and luminous quasars and others showing no such association. Recent
observations have shown that a black hole is likely to become heavily obscured
behind merger-driven gas and dust, even in the early stages of the merger, when
the galaxies are well separated (5 to 40 kiloparsecs). Merger simulations
further suggest that such obscuration and black-hole accretion peaks in the
final merger stage, when the two galactic nuclei are closely separated (less
than 3 kiloparsecs). Resolving this final stage requires a combination of
high-spatial-resolution infrared imaging and high-sensitivity hard-X-ray
observations to detect highly obscured sources. However, large numbers of
obscured luminous accreting supermassive black holes have been recently
detected nearby (distances below 250 megaparsecs) in X-ray observations. Here
we report high-resolution infrared observations of hard-X-ray-selected black
holes and the discovery of obscured nuclear mergers, the parent populations of
supermassive-black-hole mergers. We find that obscured luminous black holes
(bolometric luminosity higher than 2x10^44 ergs per second) show a significant
(P<0.001) excess of late-stage nuclear mergers (17.6 per cent) compared to a
sample of inactive galaxies with matching stellar masses and star formation
rates (1.1 per cent), in agreement with theoretical predictions. Using
hydrodynamic simulations, we confirm that the excess of nuclear mergers is
indeed strongest for gas-rich major-merger hosts of obscured luminous black
holes in this final stage.Comment: To appear in the 8 November 2018 issue of Nature. This is the
authors' version of the wor
Supercritical Carbon Dioxide Extraction of Bioactive Compounds from Ampelopsis grossedentata Stems: Process Optimization and Antioxidant Activity
Supercritical carbon dioxide (SC-CO2) extraction of bioactive compounds including flavonoids and phenolics from Ampelopsis grossedentata stems was carried out. Extraction parameters such as pressure, temperature, dynamic time and modifier, were optimized using an orthogonal array design of L9 (34), and antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and ferrous ion chelating (FIC) assay. The best conditions obtained for SC-CO2 extraction of flavonoids was 250 bar, 40 °C, 50 min, and with a modifier of methanol/ethanol (1:3, v/v), and that for phenolics extraction was 250 bar, 40 °C, 50 min, and with a modifier of methanol/ethanol (1:1, v/v). Meantime, flavonoids and phenolics were found to be mainly responsible for the DPPH scavenging activity of the extracts, but not for the chelating activity on ferrous ion according to Pearson correlation analysis. Furthermore, several unreported flavonoids such as apigenin, vitexin, luteolin, etc., have been detected in the extracts from A. grossedentata stems
Sustainable development of a GCP-compliant clinical trials platform in Africa: the Malaria Clinical Trials Alliance perspective
BACKGROUND: The Malaria Clinical Trials Alliance (MCTA), a programme of INDEPTH network of demographic surveillance centres, was launched in 2006 with two broad objectives: to facilitate the timely development of a network of centres in Africa with the capacity to conduct clinical trials of malaria vaccines and drugs under conditions of good clinical practice (GCP); and to support, strengthen and mentor the centres in the network to facilitate their progression towards self-sustaining clinical research centres. CASE DESCRIPTION: Sixteen research centres in 10 African malaria-endemic countries were selected that were already working with the Malaria Vaccine Initiative (MVI) or the Medicines for Malaria Venture (MMV). All centres were visited to assess their requirements for research capacity development through infrastructure strengthening and training. Support provided by MCTA included: laboratory and facility refurbishment; workshops on GCP, malaria diagnosis, strategic management and media training; and training to support staff to undertake accreditation examinations of the Association of Clinical Research Professionals (ACRP). Short attachments to other network centres were also supported to facilitate sharing practices within the Alliance. MCTA also played a key role in the creation of the African Media & Malaria Research Network (AMMREN), which aims to promote interaction between researchers and the media for appropriate publicity and media reporting of research and developments on malaria, including drug and vaccine trials. CONCLUSION: In three years, MCTA strengthened 13 centres to perform GCP-compliant drug and vaccine trials, including 11 centres that form the backbone of a large phase III malaria vaccine trial. MCTA activities have demonstrated that centres can be brought up to GCP compliance on this time scale, but the costs are substantial and there is a need for further support of other centres to meet the growing demand for clinical trial capacity. The MCTA experience also indicates that capacity development in clinical trials is best carried out in the context of preparation for specific trials. In this regard MCTA centres involved in the phase III malaria vaccine trial were, on average, more successful at consolidating the training and infrastructure support than those centres focussing only on drug trials
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