30 research outputs found
Surgical treatment of sinus mucocele in miniature horse breeds : long-term follow-up of 7 cases
The Rotation Period of the Planet-Hosting Star HD 189733
We present synoptic optical photometry of HD 189733, the chromospherically
active parent star of one of the most intensively studied exoplanets. We have
significantly extended the timespan of our previously reported observations and
refined the estimate of the stellar rotation period by more than an order of
magnitude: days. We derive a lower limit on the
inclination of the stellar rotation axis of 56\arcdeg (with 95% confidence),
corroborating earlier evidence that the stellar spin axis and planetary orbital
axis are well aligned.Comment: To appear in A
Preliminary investigation comparing a detomidine continuous rate infusion combined with either morphine or buprenorphine for standing sedation in horses
Properties of Galaxies Hosting X-ray Selected Active Galactic Nuclei in the Cl1604 Supercluster at z=0.9
To investigate the role of feedback from Active Galactic Nuclei (AGN) in
driving the evolution of their host galaxies, we have carried out a study of
the environments and optical properties of galaxies harboring X-ray luminous
AGN in the Cl1604 supercluster at z~0.9. Making use of Chandra, HST/ACS and
Keck/DEIMOS observations, we examine the integrated colors, morphologies and
spectral properties of nine moderate-luminosity (L_x ~ 10^43 erg s^-1) type 2
Seyferts detected in the Cl1604 complex. We find that the AGN are predominantly
hosted by luminous spheroids and/or bulge dominated galaxies which have colors
that place them in the valley between the blue cloud and red sequence in
color-magnitude space, consistent with predictions that AGN hosts should
constitute a transition population. Half of the hosts have bluer overall colors
as a result of blue resolved cores in otherwise red spheroids and a majority
show signs of recent or pending interactions. We also find a substantial number
exhibit strong Balmer absorption features indicative of post-starburst
galaxies, despite the fact that we detect narrow [OII] emission lines in all of
the host spectra. If the [OII] lines are due in part to AGN emission, as we
suspect, then this result implies that a significant fraction of these galaxies
(44%) have experienced an enhanced level of star formation within the last ~1
Gyr which was rapidly suppressed. Overall we find that the properties of the
nine host galaxies are generally consistent with a scenario in which recent
interactions have triggered both increased levels of nuclear activity and an
enhancement of centrally concentrated star formation, followed by a rapid
truncation of the latter, possibly as a result of feedback from the AGN itself.
[Abridged]Comment: 15 pages, 9 Figures, submitted to Ap
The nature and space density of fossil groups of galaxies
We describe the properties of a sample of galaxy groups with very unusual
distributions of galaxy luminosities. The most extreme example has an X-ray
luminosity similar to that of the Virgo cluster but has a very low richness,
with only one galaxy brighter than L*, compared with six in Virgo. That one
galaxy, however, is optically more luminous than any galaxy in Virgo and has an
optical luminosity as bright as many of the central cD galaxies in rich Abell
clusters. The characteristic feature of the fossil groups we study is that most
of the light arises from one dominant, central galaxy. We define a fossil
system and, based on this definition, construct a small X-ray selected,
flux-limited sample of fossil groups with well known selection criteria. We
confirm that these systems are indeed groups of galaxies, but dominated by one
central luminous giant elliptical galaxy and with few, or no, L* galaxies. We
find that fossil systems represent 8%-20% of all systems of the same X-ray
luminosity. Fossil groups are at least as numerous as all poor and rich
clusters combined, and are thus a possible site for the formation of luminous
central cluster galaxies before infall into clusters occurs. The fossil systems
in our sample have significantly higher X-ray luminosities than normal groups
of similar total optical luminosities (or similar X-ray temperature, where the
latter can be measured). These enhanced X-ray luminosities may be due to
relatively cool gas in the innermost regions or due to a low central gas
entropy. We interpret fossil groups as old, undisturbed systems which have
avoided infall into clusters, but where galaxy merging of most of the L*
galaxies has occurred. An early formation epoch, before that of most groups,
could explain low central gas entropies and high X-ray luminosities.Comment: to appear in MNRAS, 13 pages, 8 figure
Inhibition of G Protein-Activated Inwardly Rectifying K+ Channels by Different Classes of Antidepressants
Various antidepressants are commonly used for the treatment of depression and several other neuropsychiatric disorders. In addition to their primary effects on serotonergic or noradrenergic neurotransmitter systems, antidepressants have been shown to interact with several receptors and ion channels. However, the molecular mechanisms that underlie the effects of antidepressants have not yet been sufficiently clarified. G protein-activated inwardly rectifying K+ (GIRK, Kir3) channels play an important role in regulating neuronal excitability and heart rate, and GIRK channel modulation has been suggested to have therapeutic potential for several neuropsychiatric disorders and cardiac arrhythmias. In the present study, we investigated the effects of various classes of antidepressants on GIRK channels using the Xenopus oocyte expression assay. In oocytes injected with mRNA for GIRK1/GIRK2 or GIRK1/GIRK4 subunits, extracellular application of sertraline, duloxetine, and amoxapine effectively reduced GIRK currents, whereas nefazodone, venlafaxine, mianserin, and mirtazapine weakly inhibited GIRK currents even at toxic levels. The inhibitory effects were concentration-dependent, with various degrees of potency and effectiveness. Furthermore, the effects of sertraline were voltage-independent and time-independent during each voltage pulse, whereas the effects of duloxetine were voltage-dependent with weaker inhibition with negative membrane potentials and time-dependent with a gradual decrease in each voltage pulse. However, Kir2.1 channels were insensitive to all of the drugs. Moreover, the GIRK currents induced by ethanol were inhibited by sertraline but not by intracellularly applied sertraline. The present results suggest that GIRK channel inhibition may reveal a novel characteristic of the commonly used antidepressants, particularly sertraline, and contributes to some of the therapeutic effects and adverse effects
GJ 273: On the formation, dynamical evolution, and habitability of a planetary system hosted by an M dwarf at 3.75 parsec
Context. Planets orbiting low-mass stars such as M dwarfs are now considered a cornerstone in the search for life-harbouring planets.
GJ 273 is a planetary system orbiting an M dwarf only 3.75 pc away, composed of two confirmed planets, GJ 273b and GJ 273c, and
two promising candidates, GJ 273d and GJ 273e. Planet GJ 273b resides in the habitable zone. Currently, due to a lack of observed
planetary transits, only the minimum masses of the planets are known: Mb sin ib=2.89 M⊕, Mc sin ic=1.18 M⊕, Md sin id=10.80 M⊕,
and Me sin ie=9.30 M⊕. Despite being an interesting system, the GJ 273 planetary system is still poorly studied.
Aims. We aim at precisely determine the physical parameters of the individual planets, in particular to break the mass–inclination
degeneracy to accurately determine the mass of the planets. Moreover, we present thorough characterisation of planet GJ 273b in
terms of its potential habitability.
Methods. First, we explored the planetary formation and hydration phases of GJ 273 during the first 100 Myr. Secondly, we analysed
the stability of the system by considering both the two- and four-planet configurations. We then performed a comparative analysis
between GJ 273 and the Solar System, and searched for regions in GJ 273 which may harbour minor bodies in stable orbits, i.e. main
asteroid belt and Kuiper belt analogues.
Results. From our set of dynamical studies, we obtain that the four-planet configuration of the system allows us to break the mass–
inclination degeneracy. From our modelling results, the masses of the planets are unveiled as: 2:89 ≤ Mb ≤ 3:03 M⊕, 1:18 ≤ Mc ≤
1:24 M⊕, 10:80 ≤ Md ≤ 11:35 M⊕ and 9:30 ≤ Me ≤ 9:70 M⊕. These results point to a system likely composed of an Earth-mass
planet, a super-Earth and two mini-Neptunes. From planetary formation models, we determine that GJ 273b was likely an efficient
water captor while GJ 273c is probably a dry planet. We found that the system may have several stable regions where minor bodies
might reside. Collectively, these results are used to comprehensively discuss the habitability of GJ 273bSpanish Ministry of Science and Education RamĂłn y Cajal programme
ESP2017-87676-2-2
RYC-2012-09913CONICYT- FONDECYT/Chile Postdoctorado 3180405MIT’s Kavli Institut
The James Webb Space Telescope
The James Webb Space Telescope (JWST) is a large (6.6m), cold (50K),
infrared-optimized space observatory that will be launched early in the next
decade. The observatory will have four instruments: a near-infrared camera, a
near-infrared multi-object spectrograph, and a tunable filter imager will cover
the wavelength range, 0.6 to 5.0 microns, while the mid-infrared instrument
will do both imaging and spectroscopy from 5.0 to 29 microns. The JWST science
goals are divided into four themes. The End of the Dark Ages: First Light and
Reionization theme seeks to identify the first luminous sources to form and to
determine the ionization history of the early universe. The Assembly of
Galaxies theme seeks to determine how galaxies and the dark matter, gas, stars,
metals, morphological structures, and active nuclei within them evolved from
the epoch of reionization to the present day. The Birth of Stars and
Protoplanetary Systems theme seeks to unravel the birth and early evolution of
stars, from infall on to dust-enshrouded protostars to the genesis of planetary
systems. The Planetary Systems and the Origins of Life theme seeks to determine
the physical and chemical properties of planetary systems including our own,
and investigate the potential for the origins of life in those systems. To
enable these observations, JWST consists of a telescope, an instrument package,
a spacecraft and a sunshield. The telescope consists of 18 beryllium segments,
some of which are deployed. The segments will be brought into optical alignment
on-orbit through a process of periodic wavefront sensing and control. The JWST
operations plan is based on that used for previous space observatories, and the
majority of JWST observing time will be allocated to the international
astronomical community through annual peer-reviewed proposal opportunities.Comment: 96 pages, including 48 figures and 15 tables, accepted by Space
Science Review