717 research outputs found
Mutants and Assay System to Identify USP/RXR Ligands
The invention relates to mutant nuclear hormone receptors that encode mutant nuclear hormone receptors, in which particular amino acid residues are substituted with respect to wild type, so as to be able to detect ligand binding to the mutant receptor by either a change in a physical property of the mutant receptor and/or an transcriptional induction of a nuclear hormone receptor construct. The invention also relates to a nuclear hormone receptor response element denoted by the formula YDRXZ comprising a direct repeat (DR) comprising two half sites separated by X nucleic acid bases; wherein Z indicates the presence of at least one DR oriented in either a forward or reverse orientation; wherein Y equals 1 to 8 forward and/or reverse direct repeats; and X equals 1 to about 12
Towards the idea of total local sustainable places
Abstract The provision of local public services has to be re-thought from bottom to top Major demographic changes and migration patterns are transforming local cultures and communities and are challenging many long-established approaches to service provision. Additionally, in the internet-age, citizens expect to have choice and potential voice, when they want it. Involving citizens and service users in decision-making and budget choices will increasingly become the norm. These challenges require more than 'tinkering at the edges' or incremental adjustment. They will only be achieved through root and branch change and will have to be led from the bottom, as well as the top
The 2MASS Wide-Field T Dwarf Search. IV Unting out T dwarfs with Methane Imaging
We present first results from a major program of methane filter photometry
for low-mass stars and brown dwarfs. The definition of a new methane filter
photometric system is described. A recipe is provided for the differential
calibration of methane imaging data using existing 2MASS photometry. We show
that these filters are effective in discriminating T dwarfs from other types of
stars, and demonstrate this with Anglo-Australian Telescope observations using
the IRIS2 imager. Methane imaging data and proper motions are presented for ten
T dwarfs identified as part of the 2MASS "Wide Field T Dwarf Search" -- seven
of them initially identified as T dwarfs using methane imaging.
We also present near-infrared moderate resolution spectra for five T dwarfs,
newly discovered by this technique. Spectral types obtained from these spectra
are compared to those derived from both our methane filter observations, and
spectral types derived by other observers. Finally, we suggest a range of
future programs to which these filters are clearly well suited: the winnowing
of T dwarf and Y dwarf candidate objects coming from the next generation of
near-infrared sky surveys; the robust detection of candidate planetary-mass
brown dwarfs in clusters; the detection of T dwarf companions to known L and T
dwarfs via deep methane imaging; and the search for rotationally-modulated
time-variable surface features on cool brown dwarfs.Comment: 20 pages. To appear in The Astronomical Journal, Nov. 200
The NIRSPEC Brown Dwarf Spectroscopic Survey II: High-Resolution J-Band Spectra of M, L and T Dwarfs
We present a sequence of high resolution (R~20,000 or 15 km/s) infrared
spectra of stars and brown dwarfs spanning spectral types M2.5 to T6.
Observations of 16 objects were obtained using eight echelle orders to cover
part of the J-band from 1.165-1.323 micron with NIRSPEC on the Keck II
telescope. By comparing opacity plots and line lists, over 200 weak features in
the J-band are identified with either FeH or H2O transitions. Absorption by FeH
attains maximum strength in the mid-L dwarfs, while H2O absorption becomes
systematically stronger towards later spectral types. Narrow resolved features
broaden markedly after the M to L transition. Our high resolution spectra also
reveal that the disappearance of neutral Al lines at the boundary between M and
L dwarfs is remarkably abrupt, presumably because of the formation of grains.
Neutral Fe lines can be traced to mid-L dwarfs before Fe is removed by
condensation. The neutral potassium (K I) doublets that dominate the J-band
have pressure broadened wings that continue to broaden from ~50 km/s (FWHM) at
mid-M to ~500 km/s at mid-T. In contrast however, the measured
pseudo-equivalent widths of these same lines reach a maximum in the mid-L
dwarfs. The young L2 dwarf, G196-3B, exhibits narrow potassium lines without
extensive pressure-broadened wings, indicative of a lower gravity atmosphere.
Kelu-1AB, another L2, has exceptionally broad infrared lines, including FeH and
H2O features, confirming its status as a rapid rotator. In contrast to other
late T objects, the peculiar T6 dwarf 2MASS 0937+29 displays a complete absence
of potassium even at high resolution, which may be a metallicity effect or a
result of a cooler, higher-gravity atmosphere.Comment: 53 pages, 21 figures, data will be available at
http://www.astro.ucla.edu/~mclean/BDSSarchive
Parallaxes and Infrared Photometry of three Y0 dwarfs
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We have followed up the three Y0 dwarfs WISEPA J041022.71+150248.5, WISEPA J173835.53+273258.9 and WISEPC J205628.90+145953.3 using the UKIRT/WFCAM telescope/instruments. We find parallaxes that are more consistent and accurate than previously published values. We estimate absolute magnitudes in photometric pass-bands from to and find them to be consistent between the three Y0 dwarfs indicating the inherent cosmic absolute magnitude spread of these objects is small. We examine the MKO magnitudes over the four year time line and find small but significant monotonic variations. Finally we estimate physical parameters from a comparison of spectra and parallax to equilibrium and non-equilibrium models finding values consistent with solar metallicity, an effective temperature of 450-475\,K and log~g of 4.0-4.5.Peer reviewe
A search for L dwarf binary systems
We present analysis of HST Planetary Camera images of twenty L dwarfs
identified in the course of the Two Micron All-Sky Survey. Four of the targets
have faint, red companions at separations between 0.07 and 0.29 arcseconds (1.6
to 7.6 AU). In three cases, the bolometric magnitudes of the components differ
by less than 0.3 magnitudes. Since the cooling rate for brown dwarfs is a
strong function of mass, similarity in luminosities implies comparable masses.
The faint component in the 2M0850 system, however, is over 1.3 magnitudes
fainter than the primary in the I-band, and ~0.8 magnitudes fainter in M(bol).
Indeed, 2M0850B is ~0.8 magnitudes fainter in I than the lowest luminosity L
dwarf currently known, while the absolute magnitude we deduce at J is almost
identical with M_J for Gl 229B. Theoretical models indicate a mass ratio of
\~0.75. The mean separation of the L dwarf binaries in the current sample is
smaller by a factor of two than amongst M dwarfs. We discuss the implications
of these results for the temperature scale in the L/T transition region and for
the binary frequency amongst L dwarfs.Comment: 38 pages, 11 figures; accepted for A
The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low-Resolution Near-Infrared Spectra
We present the first results of a near-infrared (0.96-2.31 micron)
spectroscopic survey of M, L, and T dwarfs obtained with NIRSPEC on the Keck II
telescope. Our new survey has a resolving power of R = 2000 and is comprised of
two major data sets: 53 J-band (1.14-1.36 micron) spectra covering all spectral
types from M6 to T8 with at least two members in each spectral subclass
(wherever possible), and 25 flux-calibrated spectra from 1.14 to 2.31 microns
for most spectral classes between M6 and T8. Sixteen of these 25 objects have
additional spectral coverage from 0.96-1.14 microns to provide overlap with
optical spectra. Spectral flux ratio indexes for prominent molecular bands are
derived and equivalent widths (EWs) for several atomic lines are measured. We
find that a combination of four H2O and two CH4 band strengths can be used for
spectral classification. Weak (EW~1-2 angstrom) atomic lines of Al I and Ca I
disappear at the boundary between M and L types.Comment: 60 pages, 25 figures. To appear in the Astrophysical Journal Vol 596.
Received 2003 March 31; accepted 2003 June 20. Web site at
http://www.astro.ucla.edu/~mclean/BDSSarchiv
J-Band Infrared Spectroscopy of a Sample of Brown Dwarfs Using Nirspec on Keck II
Near-infrared spectroscopic observations of a sample of very cool, low-mass
objects are presented with higher spectral resolution than in any previous
studies. Six of the objects are L-dwarfs, ranging in spectral class from L2 to
L8/9, and the seventh is a methane or T-dwarf. These new observations were
obtained during commissioning of NIRSPEC, the first high-resolution
near-infrared cryogenic spectrograph for the Keck II 10-meter telescope on
Mauna Kea, Hawaii. Spectra with a resolving power of R=2500 from 1.135 to 1.360
microns (approximately J-band) are presented for each source. At this
resolution, a rich spectral structure is revealed, much of which is due to
blending of unresolved molecular transitions. Strong lines due to neutral
potassium (K I), and bands due to iron hydride (FeH) and steam (H2O) change
significantly throughout the L sequence. Iron hydride disappears between L5 and
L8, the steam bands deepen and the K I lines gradually become weaker but wider
due to pressure broadening. An unidentified feature occurs at 1.22 microns
which has a temperature dependence like FeH but has no counterpart in the
available FeH opacity data. Because these objects are 3-6 magnitudes brighter
in the near-infrared compared to the I-band, spectral classification is
efficient. One of the objects studied (2MASSW J1523+3014) is the coolest
L-dwarf discovered so far by the 2-Micron All-Sky Survey (2MASS), but its
spectrum is still significantly different from the methane-dominated objects
such as Gl229B or SDSS 1624+0029.Comment: New paper, Latex format, 2 figures, accepted to ApJ Letter
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