2,669 research outputs found
Room-temperature Polymerisation Of Ethylene On A Tio2 (anatase) Surface; Infrared Spectroscopic Evidence For An Alkylidene-ti4+ Polymer End-group And For A 'hydrogen-bonding' Type Of Interaction Of Ch Bonds Of The Polymer Chain With The Oxide Surface
An infrared spectroscopic study of the spontaneous polymerisation of ethylene on a sulphate-containing TiO2 (anatase) sample shows evidence for an alkylidene surface end-group of the polymer and for substantial perturbation of CH2 groups of the polymer chain by interaction with the oxide surface.2112581259DARPA; Defense Advanced Research Projects Agency; NSF; Defense Advanced Research Projects Agenc
The Anti-Coincidence Detector for the GLAST Large Area Telescope
This paper describes the design, fabrication and testing of the
Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope
(GLAST) Large Area Telescope (LAT). The ACD is LAT first-level defense against
the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders
of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector,
requiring a total active area of ~8.3 square meters. The ACD detector utilizes
plastic scintillator tiles with wave-length shifting fiber readout. In order to
suppress self-veto by shower particles at high gamma-ray energies, the ACD is
segmented into 89 tiles of different sizes. The overall ACD efficiency for
detection of singly charged relativistic particles entering the tracking
detector from the top or sides of the LAT exceeds the required 0.9997.Comment: 33 pages, 19 figure
The Parkes Multibeam Pulsar Survey: PSR J1811-1736 - a pulsar in a highly eccentric binary system
We are undertaking a high-frequency survey of the Galactic plane for radio
pulsars, using the 13-element multibeam receiver on the 64-m Parkes radio
telescope. We describe briefly the survey system and some of the initial
results. PSR J1811-1736, one of the first pulsars discovered with this system,
has a rotation period of 104 ms. Subsequent timing observations using the 76-m
radio telescope at Jodrell Bank show that it is in an 18.8-day,
highly-eccentric binary orbit. We have measured the rate of advance of
periastron which indicates a total system mass of 2.6 +- 0.9 Msun, and the
minimum companion mass is about 0.7 Msun. This, the high orbital eccentricity
and the recycled nature of the pulsar suggests that this system is composed of
two neutron stars, only the fourth or fifth such system known in the disk of
the Galaxy.Comment: 6 pages, 3 embedded EPS figures, to be published in MNRA
Perfect Reflection of Light by an Oscillating Dipole
We show theoretically that a directional dipole wave can be perfectly
reflected by a single point-like oscillating dipole. Furthermore, we find that
in the case of a strongly focused plane wave up to 85 % of the incident light
can be reflected by the dipole. Our results hold for the full spectrum of the
electromagnetic interactions and have immediate implications for achieving
strong coupling between a single propagating photon and a single quantum
emitter.Comment: 3 figure
Short-term variability of a sample of 29 trans-Neptunian objects and Centaurs
We present results of 6 years of observations, reduced and analyzed with the
same tools in a systematic way. We report completely new data for 15 objects,
for 5 objects we present a new analysis of previously published results plus
additional data and for 9 objects we present a new analysis of data already
published. Lightcurves, possible rotation periods and photometric amplitudes
are reported for all of them. The photometric variability is smaller than
previously thought: the mean amplitude of our sample is 0.1mag and only around
15% of our sample has a larger variability than 0.15mag. The smaller
variability than previously thought seems to be a bias of previous
observations. We find a very weak trend of faster spinning objects towards
smaller sizes, which appears to be consistent with the fact that the smaller
objects are more collisionally evolved, but could also be a specific feature of
the Centaurs, the smallest objects in our sample. We also find that the smaller
the objects, the larger their amplitude, which is also consistent with the idea
that small objects are more collisionally evolved and thus more deformed.
Average rotation rates from our work are 7.5h for the whole sample, 7.6h for
the TNOs alone and 7.3h for the Centaurs. All of them appear to be somewhat
faster than what one can derive from a compilation of the scientific literature
and our own results. Maxwellian fits to the rotation rate distribution give
mean values of 7.5h (for the whole sample) and 7.3h (for the TNOs only).
Assuming hydrostatic equilibrium we can determine densities from our sample
under the additional assumption that the lightcurves are dominated by shape
effects, which is likely not realistic. The resulting average density is
0.92g/cm^3 which is not far from the density constraint that one can derive
from the apparent spin barrier that we observe.Comment: Accepted for publication in A&
NICE guidance on long-term sickness and incapacity
Long-term sickness absence and incapacity benefits (disability pension) rates have increased across industrialised countries. Effective measures are needed to support return to work. The recommendations of this guidance were informed by the most appropriate available evidence of effectiveness and cost-effectiveness. Public health evidence was provided by research using a variety of study designs that attempted to determine the outcome of a particular intervention by evaluating status before and after the intervention had been effected, and was not limited to randomised control trials. Where the evidence base was depleted or underdeveloped, expert witnesses were called to give their opinion on the best available evidence and emerging interventions. The process enabled challenge and contestability from stakeholder groups at different points as the guidance was developed. Forty-five heterogeneous studies were included in the review of interventions to reduce long-term sickness absence and transitions from short-term to long-term absence (mainly covering the former and also mainly examining musculoskeletal conditions). The analysis of evidence was restricted to descriptive synthesis. Three general themes emerged from an analysis of the studies that were more likely to report positive results: early interventions; multidisciplinary approaches; and interventions with a workplace component. Two further reviews were undertaken, one on interventions to reduce the re-occurrence of sickness absence, which identified seven studies on lower back pain, and concluded that early intervention and direct workplace input are important factors. The final evidence review focused on six studies of interventions for those in receipt of incapacity benefit. The evidence was that work-focused interviews coupled with access to tailored support are effective and cost-effective interventions. Practitioners should consider the impact of interventions and management options on work ability for patients of working age. Work ability should be considered a key outcome for future intervention studies
Pathwise Sensitivity Analysis in Transient Regimes
The instantaneous relative entropy (IRE) and the corresponding instanta-
neous Fisher information matrix (IFIM) for transient stochastic processes are
pre- sented in this paper. These novel tools for sensitivity analysis of
stochastic models serve as an extension of the well known relative entropy rate
(RER) and the corre- sponding Fisher information matrix (FIM) that apply to
stationary processes. Three cases are studied here, discrete-time Markov
chains, continuous-time Markov chains and stochastic differential equations. A
biological reaction network is presented as a demonstration numerical example
The Bivariate Normal Copula
We collect well known and less known facts about the bivariate normal
distribution and translate them into copula language. In addition, we prove a
very general formula for the bivariate normal copula, we compute Gini's gamma,
and we provide improved bounds and approximations on the diagonal.Comment: 24 page
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