847 research outputs found
Properties and occurrence rates of exoplanet candidates as a function of host star metallicity from the DR25 catalog
Correlations between the occurrence rate of exoplanets and their host star
properties provide important clues about the planet formation processes. We
studied the dependence of the observed properties of exoplanets (radius, mass,
and orbital period) as a function of their host star metallicity. We analyzed
the planetary radii and orbital periods of over 2800 candidates from
the latest data release DR25 (Q1-Q17) with revised planetary radii
based on ~DR2 as a function of host star metallicity (from the Q1-Q17
(DR25) stellar and planet catalog). With a much larger sample and improved
radius measurements, we are able to reconfirm previous results in the
literature. We show that the average metallicity of the host star increases as
the radius of the planet increases. We demonstrate this by first calculating
the average host star metallicity for different radius bins and then
supplementing these results by calculating the occurrence rate as a function of
planetary radius and host star metallicity. We find a similar trend between
host star metallicity and planet mass: the average host star metallicity
increases with increasing planet mass. This trend, however, reverses for masses
: host star metallicity drops with increasing planetary
mass. We further examined the correlation between the host star metallicity and
the orbital period of the planet. We find that for planets with orbital periods
less than 10 days, the average metallicity of the host star is higher than that
for planets with periods greater than 10 days.Comment: 14 pages, 13 Figures, Accepted for publication in The Astronomical
Journa
Selective Detection of NADPH Oxidase in Polymorphonuclear Cells by Means of NAD(P)H-Based Fluorescence Lifetime Imaging
NADPH oxidase (NOX2) is a multisubunit membrane-bound enzyme complex that, upon assembly in activated cells,
catalyses the reduction of free oxygen to its superoxide anion, which further leads to reactive oxygen species (ROS) that are
toxic to invading pathogens, for example, the fungus Aspergillus fumigatus. Polymorphonuclear cells (PMNs) employ both
nonoxidative and oxidative mechanisms to clear this fungus from the lung. The oxidative mechanisms mainly depend on the
proper assembly and function of NOX2. We identified for the first time the NAD(P)H-dependent enzymes involved in such
oxidative mechanisms by means of biexponential NAD(P)H-fluorescence lifetime imaging (FLIM). A specific fluorescence
lifetime of 3670±140 picoseconds as compared to 1870 picoseconds for NAD(P)H bound to mitochondrial enzymes could be
associated with NADPH bound to oxidative enzymes in activated PMNs. Due to its predominance in PMNs and due to the
use of selective activators and inhibitors, we strongly believe that this specific lifetime mainly originates from NOX2. Our
experiments also revealed the high site specificity of the NOX2 assembly and, thus, of the ROS production as well as the
dynamic nature of these phenomena. On the example of NADPH oxidase, we demonstrate the potential of NAD(P)H-based
FLIM in selectively investigating enzymes during their cellular function
Identifying the population of T-Tauri stars in Taurus: UV-optical synergy
With the third data release of the Gaia mission DR3 with its precise
photometry and astrometry, it is now possible to study the behaviour of stars
at a scale never seen before. In this paper, we developed new criteria to
identify T-Tauri stars (TTS) candidates using UV and optical CMDs by combining
the GALEX and Gaia surveys. We found 19 TTS candidates and 5 of them are newly
identified TTS in the Taurus Molecular Cloud (TMC), not catalogued before as
TMC members. For some of the TTS candidates, we also obtained optical spectra
from several Indian telescopes. We also present the analysis of the distance
and proper motion of young stars in the Taurus using data from DR3. We
found that the stars in Taurus show a bimodal distribution with distance,
having peaks at pc and pc. The
reason for this bimodality, we think, is due to the fact that different clouds
in the TMC region are at different distances. We further show that the two
populations have similar ages and proper motion distribution. Using the
DR3 colour-magnitude diagram, we show that the age of Taurus is consistent with
1 Myr.Comment: 13 pages, 10 figure
Bacterial distribution in the lungs of children with protracted bacterial bronchitis
OBJECTIVES: Flexible bronchoscopy with bronchoalveolar lavage (FB-BAL) is increasingly used for the microbiological confirmation of protracted bacterial bronchitis (PBB) in children with a chronic wet cough. At our centre, when performing FB-BAL for microbiological diagnosis we sample 6 lobes (including lingula) as this is known to increase the rate of culture positive procedures in children with cystic fibrosis. We investigated if this is also the case in children with PBB. METHODS: We undertook a retrospective case note review of 50 children investigated for suspected PBB between May 2011 and November 2013. RESULTS: The median (IQR) age at bronchoscopy was 2.9 (1.7-4.4) years and the median (IQR) duration of cough was 11 (8.0-14) months. Positive cultures were obtained from 41/50 (82%) and 16 (39%) of these patients isolated ≥2 organisms. The commonest organisms isolated were Haemophilus influenzae (25 patients), Moraxella catarrhalis (14 patients), Staphylococcus aureus (11 patients) and Streptococcus pneumoniae (8 patients). If only one lobe had been sampled (as per the European Respiratory Society guidance) 17 different organisms would have been missed in 15 patients, 8 of whom would have had no organism cultured at all. The FB-BAL culture results led to an antibiotic other than co-amoxiclav being prescribed in 17/41 (41%) patients. CONCLUSIONS: Bacterial distribution in the lungs of children with PBB is heterogeneous and organisms may therefore be missed if only one lobe is sampled at FB-BAL. Positive FB-BAL results are useful in children with PBB and can influence treatment
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