337 research outputs found
High-resolution imaging of compact high-velocity clouds (II)
We have imaged five compact high-velocity clouds in HI with arcmin angular-
and km/s spectral-resolution using the WSRT. Supplementary total-power data,
which is fully sensitive to both the cool and warm components of HI, is
available for comparison for all the sources, albeit with angular resolutions
that vary from 3' to 36'. The fractional HI flux in compact CNM components
varies from 4% to 16% in our sample. All objects have at least one local peak
in the CNM column which exceeds about 10^19 cm^-2 when observed with arcmin
resolution. It is plausible that a peak column density of 1-2x10^19 cm^-2 is a
prerequisite for the long-term survival of these sources. One object in our
sample, CHVC120-20-443 (Davies' cloud), lies in close projected proximity to
the disk of M31. This object is characterized by exceptionally broad linewidths
in its CNM concentrations (more than 5 times greater than the median value).
These CNM concentrations lie in an arc on the edge of the source facing the M31
disk, while the diffuse HI component of this source has a position offset in
the direction of the disk. All of these attributes suggest that CHVC120-20-443
is in a different evolutionary state than most of the other CHVCs which have
been studied. Similarly broad CNM linewidths have only been detected in one
other object, CHVC111-07-466, which also lies in the Local Group barycenter
direction and has the most extreme radial velocity known. A distinct
possibility for Davies' cloud seems to be physical interaction of some type
with M31. The most likely form of this interaction might be the ram-pressure or
tidal- stripping by either one of M31's visible dwarf companions, M32 or
NGC205, or else by a dark companion with an associated HI condensation.Comment: 12 pages, 11 (low res.) png figs, accepted for pub. in A&
Integrating multiple satellite observations into a coherent dataset to monitor the full water cycle â application to the Mediterranean region
The Mediterranean region is one of the climate hotspots where the climate
change impacts are both pronounced and documented. The HyMeX
(Hydrometeorological Mediterranean eXperiment) aims to improve our
understanding of the water cycle from the meteorological to climate scales.
However, monitoring the water cycle with Earth observations (EO) is still a
challenge: EO products are multiple, and their utility is degraded by large
uncertainties and incoherences among the products. Over the Mediterranean
region, these difficulties are exacerbated by the coastal/mountainous regions
and the small size of the hydrological basins. Therefore, merging/integration
techniques have been developed to reduce these issues. We introduce here an
improved methodology that closes not only the terrestrial but also the
atmospheric and ocean budgets. The new scheme allows us to impose a spatial
and temporal multi-scale budget closure constraint. A new approach is also
proposed to downscale the results from the basin to pixel scales (at the
resolution of 0.25â). The provided Mediterranean WCÂ budget is, for
the first time, based mostly on observations such as the GRACE water storage
or the netflow at the Gibraltar Strait. The integrated dataset is in better
agreement with in situ measurements, and we are now able to estimate the
Bosporus Strait annual mean netflow.</p
A perspective on using experiment and theory to identify design principles in dye-sensitized solar cells
Dye-sensitized solar cells (DSCs) have been the subject of wide-ranging studies for many
years because of their potential for large-scale manufacturing using roll-to-roll processing
allied to their use of earth abundant raw materials. Two main challenges exist for DSC
devices to achieve this goal; uplifting device efficiency from the 12 to 14% currently
achieved for laboratory-scale âheroâ cells and replacement of the widely-used liquid
electrolytes which can limit device lifetimes. To increase device efficiency requires optimized
dye injection and regeneration, most likely from multiple dyes while replacement
of liquid electrolytes requires solid charge transporters (most likely hole transport materials
â HTMs). While theoretical and experimental work have both been widely applied to
different aspects of DSC research, these approaches are most effective when working in
tandem. In this context, this perspective paper considers the key parameters which
influence electron transfer processes in DSC devices using one or more dye molecules
and how modelling and experimental approaches can work together to optimize electron
injection and dye regeneration.
This paper provides a perspective that theory and experiment are best used in tandem to study
DSC device
Superbubble evolution including the star-forming clouds: Is it possible to reconcile LMC observations with model predictions?
Here we present a possible solution to the apparent discrepancy between the
observed properties of LMC bubbles and the standard, constant density bubble
model. A two-dimensional model of a wind-driven bubble expanding from a
flattened giant molecular cloud is examined. We conclude that the expansion
velocities derived from spherically symmetric models are not always applicable
to elongated young bubbles seen almost face-on due to the LMC orientation. In
addition, an observational test to differentiate between spherical and
elongated bubbles seen face-on is discussed.Comment: 25 pages, 7 figures, accepted to ApJ (September, 1999 issue
Efficacy of secukinumab and adalimumab in psoriatic arthritis patients with concomitant moderate to severe plaque psoriasis: results from the EXCEED, a randomised, doubleâblind headâtoâhead monotherapy study
Background:
Secukinumab [an interleukin (IL)â17A inhibitor] has demonstrated significantly higher efficacy vs. etanercept (a tumour necrosis factor inhibitor) and ustekinumab (an ILâ12/23 inhibitor) in patients with moderateâtoâsevere plaque psoriasis.
Objectives:
To report 52âweek results from a prespecified analysis of patients with active psoriatic arthritis (PsA) having concomitant moderateâtoâsevere plaque psoriasis from the headâtoâhead EXCEED monotherapy study comparing secukinumab with adalimumab.
Methods:
Patients were randomized to receive secukinumab 300 mg via subcutaneous injection at baseline, week 1â4, and then every 4 weeks until week 48 or adalimumab 40 mg via subcutaneous injection every 2 weeks from baseline until week 50. Assessments in patients with concomitant moderateâtoâsevere psoriasis, defined as having affected body surface area > 10% or Psoriasis Area and Severity Index (PASI) â„ 10 at baseline, included musculoskeletal, skin and qualityâofâlife outcomes. Missing data were handled using multiple imputation.
Results:
Of the 853 patients [secukinumab (N = 426), adalimumab (N = 427)], 211 (24·7%) had concomitant moderateâtoâsevere psoriasis [secukinumab (N = 110, 25·8%), adalimumab (N = 101, 23·7%)]. Up to week 50, 5·5% of patients discontinued secukinumab vs.17·8% in the adalimumab group. The proportion of patients who achieved American College of Rheumatology (ACR) 20 response was 76·4% with secukinumab vs. 68·3% with adalimumab (P = 0·175), PASI 100 response was 39·1% vs. 23·8% (P = 0·013), and simultaneous improvement in ACR 50 and PASI 100 response at week 52 was 28·2% vs. 17·7%, respectively (P = 0·06). Secukinumab demonstrated consistently higher responses vs. adalimumab across skin endpoints.
Conclusions:
This prespecified analysis in PsA patients with concomitant moderateâtoâsevere plaque psoriasis in the EXCEED study provides further evidence that ILâ17 inhibitors offer a comprehensive biological treatment to manage the concomitant features of psoriasis and PsA
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
On the shortness of vectors to be found by the Ideal-SVP quantum algorithm
The hardness of finding short vectors in ideals of cyclotomic number fields (hereafter, Ideal-SVP) can serve as a worst-case assumption for numerous efficient cryptosystems, via the average-case problems Ring-SIS and Ring-LWE. For a while, it could be assumed the Ideal-SVP problem was as hard a
A Wide Field, Low Frequency Radio Image of the Field of M31: II. -- Source Classification and Discussion
We have previously presented the results of a 325 MHz radio survey of M31,
conducted with the A-configuration of the Very Large Array. In this survey, a
total of 405 radio sources between <6" and 170" in extent were mapped with a
resolution of 6" and a sensitivity of ~0.6 mJy/beam. Here, we compare the
resultant source list and image with other radio, IR, optical, X-ray
observations and catalogs of the region. Through this, we were able to identify
five supernova remnant (SNR) candidates and three pulsar wind nebula (PWN)
candidates in M31, as well as three Milky Way radio stars, a possible Milky Way
Planetary Nebula, and a bevy of interesting extragalactic objects: a BL Lac, a
Giant Radio Galaxy, a galaxy merger, and several high-z radio galaxy
candidates. In addition, a large number of compact (<6") extremely steep
spectrum sources () were
detected whose nature is unknown.Comment: 30 pages, 23 tables, + 18 figures. Low-resolution figures are
available here in .jpg form. ApJS accepted, to be published in August 2005,
v159 2 issu
The liquid-glass-jamming transition in disordered ionic nanoemulsions
In quenched disordered out-of-equilibrium many-body colloidal systems, there are important distinctions between the glass transition, which is related to the onset of nonergodicity and loss of low-frequency relaxations caused by crowding, and the jamming transition, which is related to the dramatic increase in elasticity of the system caused by the deformation of constituent objects. For softer repulsive interaction potentials, these two transitions become increasingly smeared together, so measuring a clear distinction between where the glass ends and where jamming begins becomes very difficult or even impossible. Here, we investigate droplet dynamics in concentrated silicone oil-in-water nanoemulsions using light scattering. For zero or low NaCl electrolyte concentrations, interfacial repulsions are soft and longer in range, this transition sets in at lower concentrations, and the glass and the jamming regimes are smeared. However, at higher electrolyte concentrations the interactions are stiffer, and the characteristics of the glass-jamming transition resemble more closely the situation of disordered elastic spheres having sharp interfaces, so the glass and jamming regimes can be distinguished more clearly
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