59 research outputs found
Search for brown-dwarf companions of stars
The discovery of 9 new brown-dwarf candidates orbiting stars in the CORALIE
and HARPS radial-velocity surveys is reported. New CORALIE radial velocities
yielding accurate orbits of 6 previously-known hosts of potential brown-dwarf
companions are presented. Including targets selected from the literature, 33
hosts of potential brown-dwarf companions are examined. Employing innovative
methods, we use the new reduction of the Hipparcos data to fully characterise
the astrometric orbits of 6 objects, revealing M-dwarf companions with masses
between 90 M_Jup and 0.52 M_Sun. Additionally, the masses of two companions can
be restricted to the stellar domain. The companion to HD 137510 is found to be
a brown dwarf. At 95 % confidence, the companion of HD 190228 is also a brown
dwarf. The remaining 23 companions persist as brown-dwarf candidates. Based on
the CORALIE planet-search sample, we obtain an upper limit of 0.6 % for the
frequency of brown-dwarf companions around Sun-like stars. We find that the
companion-mass distribution function is rising at the lower end of the
brown-dwarf mass range, suggesting that in fact we are detecting the high-mass
tail of the planetary distribution.Comment: 24 pages, 21 figures, 10 tables. Accepted for publication in
Astronomy and Astrophysics. Abridged abstrac
The SOPHIE search for northern extrasolar planets. V. Follow-up of ELODIE candidates: Jupiter-analogs around Sun-like stars
We present radial-velocity measurements obtained in a programs underway to
search for extrasolar planets with the spectrograph SOPHIE at the 1.93-m
telescope of the Haute-Provence Observatory. Targets were selected from
catalogs observed with ELODIE, mounted previously at the telescope, in order to
detect long-period planets with an extended database close to 15 years. Two new
Jupiter-analog candidates are reported to orbit the bright stars HD150706 and
HD222155 in 16.1 and 10.9 yr at 6.7 (+4.0,-1.4) and 5.1(+0.6,-0.7) AU and to
have minimum masses of 2.71 (+1.44,-0.66) and 1.90 (+0.67,-0.53) M_Jup,
respectively. Using the measurements from ELODIE and SOPHIE, we refine the
parameters of the long-period planets HD154345b and HD89307b, and publish the
first reliable orbit for HD24040b. This last companion has a minimum mass of
4.01 +/- 0.49 M_Jup orbiting its star in 10.0 yr at 4.92 +/- 0.38 AU. Moreover,
the data provide evidence of a third bound object in the HD24040 system. With a
surrounding dust debris disk, HD150706 is an active G0 dwarf for which we
partially corrected the effect of the stellar spot on the SOPHIE
radial-velocities. HD222155 is an inactive G2V star. On the basis of the
previous findings of Lovis and collaborators and since no significant
correlation between the radial-velocity variations and the activity index are
found in the SOPHIE data, these variations are not expected to be only due to
stellar magnetic cycles. Finally, we discuss the main properties of this new
population of long-period Jupiter-mass planets, which for the moment, consists
of fewer than 20 candidates. These stars are preferential targets either for
direct-imaging or astrometry follow-up to constrain the system parameters and
for higher precision radial-velocity to search for lower mass planets, aiming
to find a Solar System twin.Comment: accepted for publication in Astronomy & Astrophysic
Circadian and Feeding Rhythms Orchestrate the Diurnal Liver Acetylome.
Lysine acetylation is involved in various biological processes and is considered a key reversible post-translational modification in the regulation of gene expression, enzyme activity, and subcellular localization. This post-translational modification is therefore highly relevant in the context of circadian biology, but its characterization on the proteome-wide scale and its circadian clock dependence are still poorly described. Here, we provide a comprehensive and rhythmic acetylome map of the mouse liver. Rhythmic acetylated proteins showed subcellular localization-specific phases that correlated with the related metabolites in the regulated pathways. Mitochondrial proteins were over-represented among the rhythmically acetylated proteins and were highly correlated with SIRT3-dependent deacetylation. SIRT3 activity being nicotinamide adenine dinucleotide (NAD) <sup>+</sup> level-dependent, we show that NAD <sup>+</sup> is orchestrated by both feeding rhythms and the circadian clock through the NAD <sup>+</sup> salvage pathway but also via the nicotinamide riboside pathway. Hence, the diurnal acetylome relies on a functional circadian clock and affects important diurnal metabolic pathways in the mouse liver
Beryllium anomalies in solar-type field stars
We present a study of beryllium (Be) abundances in a large sample of field
solar-type dwarfs and sub-giants spanning a large range of effective
temperatures. The analysis shows that Be is severely depleted for F stars, as
expected by the light-element depletion models. However, we also show that
Beryllium abundances decrease with decreasing temperature for stars cooler than
6000 K, a result that cannot be explained by current theoretical models
including rotational mixing, but that is, at least in part, expected from the
models that take into account internal wave physics. In particular, the light
element abundances of the coolest and youngest stars in our sample suggest that
Be, as well as lithium (Li), has already been burned early during their
evolution. Furthermore, we find strong evidence for the existence of a Be-gap
for solar-temperature stars. The analysis of Li and Be abundances in the
sub-giants of our sample also shows the presence of one case that has still
detectable amounts of Li, while Be is severely depleted. Finally, we compare
the derived Be abundances with Li abundances derived using the same set of
stellar parameters. This gives us the possibility to explore the temperatures
for which the onset of Li and Be depletion occurs.Comment: 16 pages, 13 figures, accepted for publication in Astronomy &
Astrophysic
Behavioural evidence for self-medication in bumblebees?
The presence of antimicrobial secondary metabolites in nectar suggests that pollinators, which are threatened globally by emergent disease, may benefit from the consumption of nectars rich in these metabolites. We tested whether nicotine, a nectar secondary metabolite common in Solanaceae and Tilia species, is used by parasitized bumblebees as a source of self-medication , using a series of toxicological, microbiological and behavioural experiments. Caged bees infected with Crithidia bombi had a slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity, though nicotine had an appetite-reducing effect overall. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion, the protozoan's viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in starved bees but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees, suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nicotine consumption did not affect bee lifespan but the reduction in the parasite load may have other likely unexplored subtle benefits both for individual bees and their colony.  Potential evidence for self-medication is discussed. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.D.B. was supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programm
Accurate p-mode measurements of the G0V metal-rich CoRoT target HD 52265
The star HD 52265 is a G0V metal-rich exoplanet-host star observed in the
seismology field of the CoRoT space telescope from November 2008 to March 2009.
The satellite collected 117 days of high-precision photometric data on this
star, showing that it presents solar-like oscillations. HD 52265 was also
observed in spectroscopy with the Narval spectrograph at the same epoch. We
characterise HD 52265 using both spectroscopic and seismic data. The
fundamental stellar parameters of HD 52265 were derived with the semi-automatic
software VWA, and the projected rotational velocity was estimated by fitting
synthetic profiles to isolated lines in the observed spectrum. The parameters
of the observed p modes were determined with a maximum-likelihood estimation.
We performed a global fit of the oscillation spectrum, over about ten radial
orders, for degrees l=0 to 2. We also derived the properties of the
granulation, and analysed a signature of the rotation induced by the
photospheric magnetic activity. Precise determinations of fundamental
parameters have been obtained: Teff = 6100 +- 60 K, log g = 4.35 +- 0.09, [M/H]
= 0.19 +- 0.05, as well as vsini = 3.6 +0.3 -1.0 km/s. We have measured a mean
rotation period P_rot = 12.3 +- 0.15 days, and find a signature of differential
rotation. The frequencies of 31 modes are reported in the range 1500-2550
micro-Hz. The large separation exhibits a clear modulation around the mean
value = 98.3 +- 0.1 micro-Hz. Mode widths vary with frequency along an
S-shape with a clear local maximum around 1800 micro-Hz. We deduce lifetimes
ranging between 0.5 and 3 days for these modes. Finally, we find a maximal
bolometric amplitude of about 3.96 +- 0.24 ppm for radial modes.Comment: published in A&A, 11 pages, 14 figures, 6 table
Homogeneous studies of transiting extrasolar planets. IV. Thirty systems with space-based light curves
I calculate the physical properties of 32 transiting extrasolar planet and
brown dwarf systems from existing photometric observations and measured
spectroscopic parameters. The systems studied include fifteen observed by
CoRoT, ten by Kepler and five by the Deep Impact spacecraft. Inclusion of the
objects studied in previous papers leads to a sample of 58 transiting systems
with homogeneously measured properties. The Kepler data include observations
from Quarter 2, and my analyses of several of the systems are the first to be
based on short-cadence data from this satellite. The light curves are modelled
using the JKTEBOP code, with attention paid to the treatment of limb darkening,
contaminating light, eccentricity, correlated noise, and numerical integration
over long exposure times. The physical properties are derived using constraints
from five sets of theoretical stellar model predictions. An alternative
approach using a calibration from eclipsing binary star systems is explored and
found to give comparable numbers. My results are in good agreement with
published properties for most of the transiting systems, but discrepancies are
identified for CoRoT-5, CoRoT-8, CoRoT-13, Kepler-5 and Kepler-7. Many of the
errorbars quoted in the literature are underestimated. Refined orbital
ephemerides are given for CoRoT-8 and for the Kepler planets. Asteroseismic
constraints on the density of the host stars are in good agreement with the
photometric equivalents for HD 17156 and TrES-2, but not for HAT-P-7 and
HAT-P-11. Complete error budgets are generated for each transiting system.
Whilst most would benefit from further photometry and spectroscopy, HD 17156,
HD 80606, HAT-P-7 and TrES-2 are now extremely well characterised. HAT-P-11 is
an exceptional candidate for studying starspots. The orbital ephemerides of
some transiting systems are becoming uncertain and they should be re-observed.Comment: Accepted for publication in MNRAS. 32 pages, lots of nice figures and
tables. A version with high-resolution figures, or a large Appendix with
detailed results, can be obtained from
http://www.astro.keele.ac.uk/~jkt/pubs.html. An online catalogue of
transiting planets, including a compilation of the results from this series
of papers, can be found at http://www.astro.keele.ac.uk/~jkt/tepcat
Salinity stress induces the production of 2-(2-phenylethyl)chromones and regulates novel classes of responsive genes involved in signal transduction in Aquilaria sinensis calli
Which method is best for the induction of labour?: A systematic review, network meta-analysis and cost-effectiveness analysis
Background: More than 150,000 pregnant women in England and Wales have their labour induced each year. Multiple pharmacological, mechanical and complementary methods are available to induce labour. Objective: To assess the relative effectiveness, safety and cost-effectiveness of labour induction methods and, data permitting, effects in different clinical subgroups. Methods: We carried out a systematic review using Cochrane methods. The Cochrane Pregnancy and Childbirth Groupâs Trials Register was searched (March 2014). This contains over 22,000 reports of controlled trials (published from 1923 onwards) retrieved from weekly searches of OVID MEDLINE (1966 to current); Cochrane Central Register of Controlled Trials (The Cochrane Library); EMBASE (1982 to current); Cumulative Index to Nursing and Allied Health Literature (1984 to current); ClinicalTrials.gov; the World Health Organization International Clinical Trials Registry Portal; and hand-searching of relevant conference proceedings and journals. We included randomised controlled trials examining interventions to induce labour compared with placebo, no treatment or other interventions in women eligible for third-trimester induction. We included outcomes relating to efficacy, safety and acceptability to women. In addition, for the economic analysis we searched the Database of Abstracts of Reviews of Effects, and Economic Evaluations Databases, NHS Economic Evaluation Database and the Health Technology Assessment database. We carried out a network meta-analysis (NMA) using all of the available evidence, both direct and indirect, to produce estimates of the relative effects of each treatment compared with others in a network. We developed a de novo decision tree model to estimate the cost-effectiveness of various methods. The costs included were the intervention and other hospital costs incurred (price year 2012â13). We reviewed the literature to identify preference-based utilities for the health-related outcomes in the model. We calculated incremental cost-effectiveness ratios, expected costs, utilities and net benefit. We represent uncertainty in the optimal intervention using cost-effectiveness acceptability curves. Results: We identified 1190 studies; 611 were eligible for inclusion. The interventions most likely to achieve vaginal delivery (VD) within 24 hours were intravenous oxytocin with amniotomy [posterior rank 2; 95% credible intervals (CrIs) 1 to 9] and higher-dose (â„ 50 ÎŒg) vaginal misoprostol (rank 3; 95% CrI 1 to 6). Compared with placebo, several treatments reduced the odds of caesarean section, but we observed considerable uncertainty in treatment rankings. For uterine hyperstimulation, double-balloon catheter had the highest probability of being among the best three treatments, whereas vaginal misoprostol (â„ 50 ÎŒg) was most likely to increase the odds of excessive uterine activity. For other safety outcomes there were insufficient data or there was too much uncertainty to identify which treatments performed âbestâ. Few studies collected information on womenâs views. Owing to incomplete reporting of the VD within 24 hours outcome, the cost-effectiveness analysis could compare only 20 interventions. The analysis suggested that most interventions have similar utility and differ mainly in cost. With a caveat of considerable uncertainty, titrated (low-dose) misoprostol solution and buccal/sublingual misoprostol had the highest likelihood of being cost-effective. Limitations: There was considerable uncertainty in findings and there were insufficient data for some planned subgroup analyses. Conclusions: Overall, misoprostol and oxytocin with amniotomy (for women with favourable cervix) is more successful than other agents in achieving VD within 24 hours. The ranking according to safety of different methods was less clear. The cost-effectiveness analysis suggested that titrated (low-dose) oral misoprostol solution resulted in the highest utility, whereas buccal/sublingual misoprostol had the lowest cost. There was a high degree of uncertainty as to the most cost-effective intervention
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