524 research outputs found
Composition-Dependent Passivation Efficiency at the CdS/CuIn1-xGaxSe2 Interface
International audienc
Constraining the mass of the planet(s) sculpting a disk cavity. The intriguing case of 2MASS J16042165-2130284
The large cavities observed in the dust and gas distributions of transition
disks may be explained by planet-disk interactions. At ~145 pc, 2MASS
J16042165-2130284 (J1604) is a 5-12 Myr old transitional disk with different
gap sizes in the mm- and m-sized dust distributions (outer edges at ~79
and at ~63 au, respectively). Its CO emission shows a ~30 au cavity.
This radial structure suggests that giant planets are sculpting this disk. We
aim to constrain the masses and locations of plausible giant planets around
J1604. We observed J1604 with the Spectro-Polarimetric High-contrast Exoplanet
REsearch (SPHERE) at the Very Large Telescope (VLT), in IRDIFS\_EXT,
pupil-stabilized mode, obtaining YJH- band images with the integral field
spectrograph (IFS) and K1K2-band images with the Infra-Red Dual-beam Imager and
Spectrograph (IRDIS). The dataset was processed exploiting the angular
differential imaging (ADI) technique with high-contrast algorithms. Our
observations reach a contrast of ~12 mag from 0.15" to 0.80"
(~22 to 115 au), but no planet candidate is detected. The disk is directly
imaged in scattered light at all bands from Y to K, and it shows a red color.
This indicates that the dust particles in the disk surface are mainly
m-sized grains. We confirm the sharp dip/decrement in
scattered light in agreement with polarized light observations. Comparing our
images with a radiative transfer model we argue that the southern side of the
disk is most likely the nearest. This work represents the deepest search yet
for companions around J1604. We reach a mass sensitivity of from ~22 to ~115 au according to a hot start scenario. We propose
that a brown dwarf orbiting inside of ~15 au and additional Jovian planets at
larger radii could account for the observed properties of J1604 while
explaining our lack of detection.Comment: 10 pages, 7 Figures. Accepted for publication in A&A . Abridged
abstrac
Resistance of uveal melanoma to the interstrand cross-linking agent mitomycin C is associated with reduced expression of CYP450R
background: Uveal melanoma (UM) is the most common primary intraocular tumour of adults, frequently metastasising to the liver. Hepatic metastases are difficult to treat and are mainly unresponsive to chemotherapy. To investigate why UM are so chemo-resistant we explored the effect of interstrand cross-linking agents mitomycin C (MMC) and cisplatin in comparison with hydroxyurea (HU).
methods: Sensitivity to MMC, cisplatin and HU was tested in established UM cell lines using clonogenic assays. The response of UM to MMC was confirmed in MTT assays using short-term cultures of primary UM. The expression of cytochrome P450 reductase (CYP450R) was analysed by western blotting, and DNA cross-linking was assessed using COMET analysis supported by γ-H2AX foci formation.
results: Both established cell lines and primary cultures of UM were resistant to the cross-linking agent MMC (in each case P<0.001 in Student's t-test compared with controls). In two established UM cell lines, DNA cross-link damage was not induced by MMC (in both cases P<0.05 in Students's t-test compared with damage induced in controls). In all, 6 out of 6 UMs tested displayed reduced expression of the metabolising enzyme CYP450R and transient expression of CYP450R increased MMC sensitivity of UM.
conclusion: We suggest that reduced expression of CYP450R is responsible for MMC resistance of UM, through a lack of bioactivation, which can be reversed by complementing UM cell lines with CYP450R
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Non-Coding RNA Sequencing of Equine Endometrium During Maternal Recognition of Pregnancy.
Maternal recognition of pregnancy (MRP) in the mare is not well defined. In a non-pregnant mare, prostaglandin F2α (PGF) is released on day 14 post-ovulation (PO) to cause luteal regression, resulting in loss of progesterone production. Equine MRP occurs prior to day 14 to halt PGF production. Studies have failed to identify a gene candidate for MRP, so attention has turned to small, non-coding RNAs. The objective of this study was to evaluate small RNA (<200 nucleotides) content in endometrium during MRP. Mares were used in a cross-over design with each having a pregnant and non-mated cycle. Each mare was randomly assigned to collection day 11 or 13 PO (n = 3/day) and endometrial biopsies were obtained. Total RNA was isolated and sequencing libraries were prepared using a small RNA library preparation kit and sequenced on a HiSeq 2000. EquCab3 was used as the reference genome and DESeq2 was used for statistical analysis. On day 11, 419 ncRNAs, representing miRNA, snRNA, snoRNA, scaRNA, and vaultRNA, were different between pregnancy statuses, but none on day 13. Equine endometrial ncRNAs with unknown structure and function were also identified. This study is the first to describe ncRNA transcriptome in equine endometrium. Identifying targets of these ncRNAs could lead to determining MRP
Quality of life and cost-effectiveness analysis of topical tranexamic acid and fibrin glue in femur fracture surgery
Altres ajuts: European Regional Development Fund (FEDER); MAPFRE Foundation (grant code SA/12/AYU/456).Background: We assessed quality of life (QoL) of patients undergoing surgery for proximal femur fracture and performed a cost-effectiveness analysis of haemostatic drugs for reducing postoperative bleeding. Methods: We analysed data from an open, multicentre, parallel, randomized controlled clinical trial (RCT) that assessed the efficacy and safety of tranexamic acid (TXA group) and fibrin glue (FG group) administered topically prior to surgical closure, compared with usual haemostasis methods (control group). For this study we conducted a cost-effectiveness analysis of these interventions from the Spanish Health System perspective, using a time horizon of 12 months. The cost was reported i
DZ Cha: a bona fide photoevaporating disc
DZ Cha is a weak-lined T Tauri star (WTTS) surrounded by a bright
protoplanetary disc with evidence of inner disc clearing. Its narrow \Ha line
and infrared spectral energy distribution suggest that DZ Cha may be a
photoevaporating disc. We aim to analyse the DZ Cha star + disc system to
identify the mechanism driving the evolution of this object. We have analysed
three epochs of high resolution optical spectroscopy, photometry from the UV up
to the sub-mm regime, infrared spectroscopy, and J-band imaging polarimetry
observations of DZ Cha. Combining our analysis with previous studies we find no
signatures of accretion in the \Ha line profile in nine epochs covering a
time baseline of years. The optical spectra are dominated by
chromospheric emission lines, but they also show emission from the forbidden
lines [SII] 4068 and [OI] 6300 that indicate a disc outflow. The
polarized images reveal a dust depleted cavity of au in radius and two
spiral-like features, and we derive a disc dust mass limit of
M_\mathrm{dust}
80 \MJup) companions are detected down to 0\farcs07 ( au,
projected). The negligible accretion rate, small cavity, and forbidden line
emission strongly suggests that DZ Cha is currently at the initial stages of
disc clearing by photoevaporation. At this point the inner disc has drained and
the inner wall of the truncated outer disc is directly exposed to the stellar
radiation. We argue that other mechanisms like planet formation or binarity
cannot explain the observed properties of DZ Cha. The scarcity of objects like
this one is in line with the dispersal timescale ( yr) predicted
by this theory. DZ Cha is therefore an ideal target to study the initial stages
of photoevaporation.Comment: A&A in press, language corrections include
Exocomet signatures around the A-shell star Leo?
We present an intensive monitoring of high-resolution spectra of the Ca {\sc
ii} K line in the A7IV shell star Leo at very short (minutes, hours),
short (night to night), and medium (weeks, months) timescales. The spectra show
remarkable variable absorptions on timescales of hours, days, and months. The
characteristics of these sporadic events are very similar to most that are
observed toward the debris disk host star Pic, which are commonly
interpreted as signs of the evaporation of solid, comet-like bodies grazing or
falling onto the star. Therefore, our results suggest the presence of solid
bodies around Leo. To our knowledge, with the exception of Pic,
our monitoring has the best time resolution at the mentioned timescales for a
star with events attributed to exocomets. Assuming the cometary scenario and
considering the timescales of our monitoring, our results indicate that
Leo presents the richest environment with comet-like events known to date,
second only to Pic.Comment: A&A letters, proof-correcte
Observations of gas flows inside a protoplanetary gap
Gaseous giant planet formation is thought to occur in the first few million
years following stellar birth. Models predict that giant planet formation
carves a deep gap in the dust component (shallower in the gas). Infrared
observations of the disk around the young star HD142527, at ~140pc, found an
inner disk ~10AU in radius, surrounded by a particularly large gap, with a
disrupted outer disk beyond 140AU, indicative of a perturbing planetary-mass
body at ~90 AU. From radio observations, the bulk mass is molecular and lies in
the outer disk, whose continuum emission has a horseshoe morphology. The
vigorous stellar accretion rate would deplete the inner disk in less than a
year, so in order to sustain the observed accretion, matter must flow from the
outer-disk into the cavity and cross the gap. In dynamical models, the putative
protoplanets channel outer-disk material into gap-crossing bridges that feed
stellar accretion through the inner disk. Here we report observations with the
Atacama Large Millimetre Array (ALMA) that reveal diffuse CO gas inside the
gap, with denser HCO+ gas along gap-crossing filaments, and that confirm the
horseshoe morphology of the outer disk. The estimated flow rate of the gas is
in the range 7E-9 to 2E-7 Msun/yr, which is sufficient to maintain accretion
onto the star at the present rate
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