863 research outputs found
Extrasolar planets and brown dwarfs around A-F type stars V. A planetary system found with HARPS around the F6IV-V star HD 60532
Aims: In the frame of the search for extrasolar planets and brown dwarfs
around early-type stars, we present the results obtained for the F-type
main-sequence star HD 60532 (F6V) with HARPS.
Methods: Using 147 spectra obtained with HARPS at La Silla on a time baseline
of two years, we study the radial velocities of this star.
Results: HD 60532 radial velocities are periodically variable, and the
variations have a Keplerian origin. This star is surrounded by a planetary
system of two planets with minimum masses of 1 and 2.5 Mjup and orbital
separations of 0.76 and 1.58 AU respectively. We also detect high-frequency,
low-amplitude (10 m/s peak-to-peak) pulsations. Dynamical studies of the system
point toward a possible 3:1 mean-motion resonance which should be confirmed
within the next decade.Comment: 7 pages, 11 figures, accepted for publication in A&
Extrasolar planets and brown dwarfs around A-F type stars - VII. Theta Cygni radial velocity variations: planets or stellar phenomenon?
(abridged) In the frame of the search for extrasolar planets and brown dwarfs
around early-type main-sequence stars, we present the results obtained on the
early F-type star Theta Cygni. Elodie and Sophie at OHP were used to obtain the
spectra. Our dedicated radial-velocity measurement method was used to monitor
the star's radial velocities over five years. We also use complementary, high
angular resolution and high-contrast images taken with PUEO at CFHT. We show
that Theta Cygni radial velocities are quasi-periodically variable, with a
~150-day period. These variations are not due to the ~0.35-Msun stellar
companion that we detected in imaging at more than 46 AU from the star. The
absence of correlation between the bisector velocity span variations and the
radial velocity variations for this 7 km/s vsini star, as well as other
criteria indicate that the observed radial velocity variations are not due to
stellar spots. The observed amplitude of the bisector velocity span variations
also seems to rule out stellar pulsations. However, we observe a peak in the
bisector velocity span periodogram at the same period as the one found in the
radial velocity periodogram, which indicates a probable link between these
radial velocity variations and the low amplitude lineshape variations which are
of stellar origin. Long-period variations are not expected from this type of
star to our knowledge. If a stellar origin (hence of new type) was to be
confirmed for these long-period radial velocity variations, this would have
several consequences on the search for planets around main-sequence stars, both
in terms of observational strategy and data analysis. An alternative
explanation for these variable radial velocities is the presence of at least
one planet of a few Jupiter masses orbiting at less than 1 AU. (abridged)Comment: 9 pages, accepted in A
Constrains on planets around beta Pic with Harps radial velocity data
Context. The {\beta} Pictoris system with its debris disk and a massive giant
planet orbiting at \simeq 9 AU represents an ideal laboratory to study giant
planet formation and evolution as well as planet-disk interactions. {\beta} Pic
b can also help testing brightness-mass relations at young ages. Other planets,
yet undetected, may of course be present in the system. Aims. We aim at putting
direct constrains on the mass of {\beta} Pic b and at searching for additional
jovian planets on orbits closer than typically 2 AU. Methods. We use high
precision Harps data collected over 8 years since 2003 to measure and analyse
{\beta} Pic radial velocities. Results. We show that the true mass of {\beta}
Pic b is less than 10, 12, 15.5, 20 and 25 MJup if orbiting respectively at 8,
9, 10, 11 and 12 AU. This is the first direct constraint on the mass of an
imaged planet. The upper mass found is well in the range predicted by
brightness-mass relations provided by current "hot start" models. We also
exclude the presence of giant planets more massive than 2.5 MJup with periods
less than 100 days (hot Jupiters), more massive than 9 MJup for periods in the
range 100-500 days. In the 500-1000 day range, the detection limit is in the
brown dwarf domain. Beyond the intrinsic interest for {\beta} Pic, these
results show the possibilities of precise RV measurements of early type,
rapidly rotating stars.Comment: 6 pages, 9 figures, to appear in Astronomy and Astrophysic
Understanding the impact of diet and nutrition on symptoms of Tourette Syndrome: A Scoping Review
This document is the accepted manuscript version. The final, definitive version of this paper has been published in Journal of Child Health Care, December 2017, published by SAGE Publishing, doi:https://doi.org/10.1177/1367493517748373.Anecdotal reports frequently suggest some dietary involvement in the maintenance of tics in children with Tourette syndrome (TS). This scoping review aimed to (1) understand the possible influence of diet as a trigger of tics and (2) map out the existing studies documenting dietary interventions in children with TS. Current evidence suggests no single diet to benefit individuals with TS. However, reports from parents of children with TS suggest that certain allergens in food may exacerbate tic-related symptoms. For example, an increase in tics has been related to the consumption of caffeine and refined sugar. Moreover, oligoantigenic diets and sugar-free diets have been identified as significantly reducing tics. More research is urgently needed to develop more accurate guidance for parents and children with TS, as many have reported using dietary and nutritional supplements, despite the lack of evidence detailing any benefits, side effects and recommended doses.Peer reviewedFinal Accepted Versio
Radial Velocities with CRIRES: Pushing precision down to 5-10 m/s
With the advent of high-resolution infrared spectrographs, Radial Velocity
(RV) searches enter into a new domain. As of today, the most important
technical question to address is which wavelength reference is the most
suitable for high-precision RV measurements.
In this work we explore the usage of atmospheric absorption features. We make
use of CRIRES data on two programs and three different targets. We re-analyze
the data of the TW Hya campaign, reaching a dispersion of about 6 m/s on the RV
standard in a time scale of roughly 1 week. We confirm the presence of a
low-amplitude RV signal on TW Hya itself, roughly 3 times smaller than the one
reported at visible wavelengths. We present RV measurements of Gl 86 as well,
showing that our approach is capable of detecting the signal induced by a
planet and correctly quantifying it.
Our data show that CRIRES is capable of reaching a RV precision of less than
10 m/s in a time-scale of one week. The limitations of this particular approach
are discussed, and the limiting factors on RV precision in the IR in a general
way. The implications of this work on the design of future dedicated IR
spectrographs are addressed as well.Comment: 9 pages, accepted for publication in A&
3D structure and formation of hydrothermal vent complexes at the Paleocene-Eocene transition, the Møre Basin, mid-Norwegian margin
Acknowledgments We thank Statoil for providing us with the PL251 (Tulipan) geophysical and geologic reports for well 6302/6- 1. We thank NORSAR for the free academic use of the SeisRox software during the modeling procedures and to Schlumberger for the free academic use of Petrel 2015. Spectral decomposition was carried out using FFA Geoteric software at the University of Aberdeen. FFA are thanked for donation of the software license to the University of Aberdeen. The authors further acknowledge the support from the Research Council of Norway through its Center of Excellence funding scheme, project 223272 (CEED), and from the MIMES project (grant no. 244155). We also gratefully acknowledge the support by the Faculty of Mathematics and Natural Sciences of the University of Oslo to TS. Clayton Grove and Craig Magee are thanked for their many insightful comments and suggestions that helped improve the paper substantially.Peer reviewedPublisher PD
Standard partition coefficients of anionic drugs in the n-octanol/water system determined by voltammetry at three-phase electrodes
The anionic forms of 26 drugs and organic model compounds have been extensively explored in the n-octanol/
water system using voltammetry at three-phase electrodes. The objective of this study was to validate the ability
of this electrochemical system to give reliable values of lipophilicity for organic ions, as well as to gain more
information on the lipophilic behaviour of anions in the n-octanol/water system. Results were used to clarify
the solvation mechanisms responsible for ion partitioning and to compare the information obtained in the
two solvent systems n-octanol/water and 1,2-dichloroethane/water
Impact of perioperative chemotherapy on survival in patients with advanced primary urethral cancer: results of the international collaboration on primary urethral carcinoma
This is the first series that suggests a prognostic benefit of neoadjuvant treatment in a consecutive series of patients who underwent perioperative chemotherapy plus surgery for advanced primary urethral carcinoma. Further studies should yield a better understanding of how perioperative chemotherapy exerts a positive effect on survival in order to selectively advocate its use in advanced primary urethral carcinom
Coherent Phonons in Carbon Nanotubes and Graphene
We review recent studies of coherent phonons (CPs) corresponding to the
radial breathing mode (RBM) and G-mode in single-wall carbon nanotubes (SWCNTs)
and graphene. Because of the bandgap-diameter relationship, RBM-CPs cause
bandgap oscillations in SWCNTs, modulating interband transitions at terahertz
frequencies. Interband resonances enhance CP signals, allowing for chirality
determination. Using pulse shaping, one can selectively excite
speci!c-chirality SWCNTs within an ensemble. G-mode CPs exhibit
temperature-dependent dephasing via interaction with RBM phonons. Our
microscopic theory derives a driven oscillator equation with a
density-dependent driving term, which correctly predicts CP trends within and
between (2n+m) families. We also find that the diameter can initially increase
or decrease. Finally, we theoretically study the radial breathing like mode in
graphene nanoribbons. For excitation near the absorption edge, the driving term
is much larger for zigzag nanoribbons. We also explain how the armchair
nanoribbon width changes in response to laser excitation.Comment: 48 pages, 41 figure
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