2,607 research outputs found
Intrinsic charge transport on the surface of organic semiconductors
The novel technique based on air-gap transistor stamps enabled realization of
the intrinsic (not dominated by static disorder) transport of the
electric-field-induced charge carriers on the surface of rubrene crystals over
a wide temperature range. The signatures of the intrinsic transport are the
anisotropy of the carrier mobility, mu, and the growth of mu with cooling. The
anisotropy of mu vanishes in the activation regime at lower temperatures, where
the charge transport becomes dominated by shallow traps. The deep traps,
deliberately introduced into the crystal by X-ray radiation, increase the
field-effect threshold without affecting the mobility. These traps filled above
the field-effect threshold do not scatter the mobile polaronic carriers.Comment: 10 pages, 4 figure
Rituximab therapy for refractory interstitial lung disease related to antisynthetase syndrome
SummaryObjectiveTo report our experience using rituximab as therapy for refractory antisynthetase syndrome (ASS)-associated interstitial lung disease.MethodsWe retrospectively evaluated the medical records of 7 ASS patients with refractory interstitial lung disease, which had previously failed to respond to prednisone and/or other cytotoxic drugs. All 7 patients received rituximab therapy, i.e.: 1 g at days 0 and 14 and at 6-month follow-up. Data on pulmonary symptoms, pulmonary function tests and high resolution computed tomography (HRCT) scan of the lungs were collected: 1) before rituximab initiation; and 2) at 6-month and one-year follow-up after the first infusion of rituximab.ResultsAt one-year follow-up, ASS patients had resolution (n = 2) or improvement of pulmonary clinical manifestations. Patients also exhibited significant improvement of interstitial lung disease parameters: 1) on pulmonary function tests: FVC (p = 0.03) and DLCO (p = 2 Ă 10â5); 2) and HRCT-scan of the lungs. Due to clinical resolution/improvement of interstitial lung disease, the median daily dose of oral prednisone could be reduced in these 7 ASS patients at one-year follow-up, compared with baseline (20 mg/day vs. 9 mg/day; p = 0.015).ConclusionOur findings suggest that rituximab may be a helpful therapy for refractory interstitial lung disease in patients with ASS
Panchromatic observations and modeling of the HV Tau C edge-on disk
We present new high spatial resolution (<~ 0.1") 1-5 micron adaptive optics
images, interferometric 1.3 mm continuum and 12CO 2-1 maps, and 350 micron, 2.8
and 3.3 mm fluxes measurements of the HV Tau system. Our adaptive optics images
reveal an unusually slow orbital motion within the tight HV Tau AB pair that
suggests a highly eccentric orbit and/or a large deprojected physical
separation. Scattered light images of the HV Tau C edge-on protoplanetary disk
suggest that the anisotropy of the dust scattering phase function is almost
independent of wavelength from 0.8 to 5 micron, whereas the dust opacity
decreases significantly over the same range. The images further reveal a marked
lateral asymmetry in the disk that does not vary over a timescale of 2 years.
We further detect a radial velocity gradient in the disk in our 12CO map that
lies along the same position angle as the elongation of the continuum emission,
which is consistent with Keplerian rotation around an 0.5-1 Msun central star,
suggesting that it could be the most massive component in the triple system. We
use a powerful radiative transfer model to compute synthetic disk observations
and use a Bayesian inference method to extract constraints on the disk
properties. Each individual image, as well as the spectral energy distribution,
of HV Tau C can be well reproduced by our models with fully mixed dust provided
grain growth has already produced larger-than-interstellar dust grains.
However, no single model can satisfactorily simultaneously account for all
observations. We suggest that future attempts to model this source include more
complex dust properties and possibly vertical stratification. (Abridged)Comment: 26 pages, 11 figures, editorially accepted for publication in Ap
Assessing the UK policies for broadband adoption
Broadband technology has been introduced to the business community and the public as a rapid way of exploiting the Internet. The benefits of its use (fast reliable connections, and always on) have been widely realised and broadband diffusion is one of the items at the top of the agenda for technology related polices of governments worldwide. In this paper an examination of the impact of the UK governmentâs polices upon broadband adoption is undertaken. Based on institutional theory a consideration of the manipulation of supply push and demand pull forces in the diffusion of broadband is offered. Using primary and secondary data sources, an analysis of the specific institutional actions related to IT diffusion as pursued by the UK government in the case of broadband is provided. Bringing the time dimension into consideration it is revealed that the UK government has shifted its attention from supply push-only strategies to more interventional ones where the demand pull forces are also mobilised. It is believed that this research will assist in the extraction of the âsuccess factorsâ in government intervention that support the diffusion of technology with a view to render favourable results if applied to other national settings
Gas and dust in the Beta Pictoris Moving Group as seen by the Herschel Space Observatory
Context. Debris discs are thought to be formed through the collisional
grinding of planetesimals, and can be considered as the outcome of planet
formation. Understanding the properties of gas and dust in debris discs can
help us to comprehend the architecture of extrasolar planetary systems.
Herschel Space Observatory far-infrared (IR) photometry and spectroscopy have
provided a valuable dataset for the study of debris discs gas and dust
composition. This paper is part of a series of papers devoted to the study of
Herschel PACS observations of young stellar associations.
Aims. This work aims at studying the properties of discs in the Beta Pictoris
Moving Group (BPMG) through far-IR PACS observations of dust and gas.
Methods. We obtained Herschel-PACS far-IR photometric observations at 70, 100
and 160 microns of 19 BPMG members, together with spectroscopic observations of
four of them. Spectroscopic observations were centred at 63.18 microns and 157
microns, aiming to detect [OI] and [CII] emission. We incorporated the new
far-IR observations in the SED of BPMG members and fitted modified blackbody
models to better characterise the dust content.
Results. We have detected far-IR excess emission toward nine BPMG members,
including the first detection of an IR excess toward HD 29391.The star HD
172555, shows [OI] emission, while HD 181296, shows [CII] emission, expanding
the short list of debris discs with a gas detection. No debris disc in BPMG is
detected in both [OI] and [CII]. The discs show dust temperatures in the range
55 to 264 K, with low dust masses (6.6*10^{-5} MEarth to 0.2 MEarth) and radii
from blackbody models in the range 3 to 82 AU. All the objects with a gas
detection are early spectral type stars with a hot dust component.Comment: 12 pages, 7 figures, 6 table
The SUGAR-DEPENDENT1 Lipase Limits Triacylglycerol Accumulation in Vegetative Tissues of Arabidopsis
Confinement effects on glass forming liquids probed by DMA
Many molecular glass forming liquids show a shift of the glass transition T-g
to lower temperatures when the liquid is confined into mesoporous host
matrices. Two contrary explanations for this effect are given in literature:
First, confinement induced acceleration of the dynamics of the molecules leads
to an effective downshift of T-g increasing with decreasing pore size. Second,
due to thermal mismatch between the liquid and the surrounding host matrix,
negative pressure develops inside the pores with decreasing temperature, which
also shifts T-g to lower temperatures. Here we present dynamic mechanical
analysis measurements of the glass forming liquid salol in Vycor and Gelsil
with pore sizes of d=2.6, 5.0 and 7.5 nm. The dynamic complex elastic
susceptibility data can be consistently described with the assumption of two
relaxation processes inside the pores: A surface induced slowed down relaxation
due to interaction with rough pore interfaces and a second relaxation within
the core of the pores. This core relaxation time is reduced with decreasing
pore size d, leading to a downshift of T-g proportional to 1/d in perfect
agreement with recent differential scanning calorimetry (DSC) measurements.
Thermal expansion measurements of empty and salol filled mesoporous samples
revealed that the contribution of negative pressure to the downshift of T-g is
small (<30%) and the main effect is due to the suppression of dynamically
correlated regions of size xi when the pore size xi approaches
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