779 research outputs found
Joining up health and bioinformatics: e-science meets e-health
CLEF (Co-operative Clinical e-Science Framework) is an MRC sponsored project in the e-Science programme that aims to establish methodologies and a technical infrastructure forthe next generation of integrated clinical and bioscience research. It is developing methodsfor managing and using pseudonymised repositories of the long-term patient histories whichcan be linked to genetic, genomic information or used to support patient care. CLEF concentrateson removing key barriers to managing such repositories ? ethical issues, informationcapture, integration of disparate sources into coherent ?chronicles? of events, userorientedmechanisms for querying and displaying the information, and compiling the requiredknowledge resources. This paper describes the overall information flow and technicalapproach designed to meet these aims within a Grid framework
VLBI observations of seven BL Lac objects from RGB sample
We present EVN observations of seven BL Lac objects selected from the RGB
sample. To investigate the intrinsic radiation property of BL Lac objects, we
estimated the Doppler factor with the VLA or MERLIN core and the total 408 MHz
luminosity for a sample of 170 BL Lac objects. The intrinsic (comoving)
synchrotron peak frequency was then calculated by using the estimated Doppler
factor. Assuming a Lorentz factor of 5, the viewing angle of jets was
constrained. The high-resolution VLBI images of seven sources all show a
core-jet structure. We estimated the proper motions of three sources with the
VLBI archive data, and find that the apparent speed increases with the distance
of components to the core for all of them. In our BL Lacs sample, the Doppler
factor of LBLs is systematically larger than that of IBLs and HBLs. We find a
significant anti-correlation between the total 408 MHz luminosity and the
intrinsic synchrotron peak frequency. However, the scatter is much larger than
for the blazar sequence. Moreover, we find a significant positive correlation
between the viewing angle and the intrinsic synchrotron peak frequency. The BL
Lac objects show a continuous distribution on the viewing angle. While LBLs
have a smaller viewing angle than that of IBLs and HBLs, IBLs are comparable to
HBLs. We conclude that the intrinsic synchrotron peak frequency is not only
related to the intrinsic radio power (though with a large scatter), but also to
the viewing angle for the present sample.Comment: 22 pages,15figures, published by A&
Variable Star Candidates in an ACS Field of M31
A search for variable stars is performed using two epochs of Hubble Space
Telescope (HST) Advanced Camera for Surveys (ACS) imaging data for a 9.28
square arcminute portion of M31. This data set reveals 254 sources that vary by
at least 4-sigma between epochs. The positions and 2-epoch B-band (equivalent)
photometry of these sources are presented. The photometry suggests that this
catalog includes most of the RR Lyrae population of this portion of M31.Comment: 22 pages, 3 tables, 5 figures, accepted for publication in A
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Effect of colloidal aggregation on the sedimentation and rheological properties of tank waste
Tank farm experience and work performed under the Tank Waste Treatment Science task of the Tank Waste Remediation System (TWRS) Pretreatment Technology Development Project indicate that colloidal interactions can have an enormous impact on tank waste processing. This report provides the theoretical and experimental background required to understand how such agglomeration phenomena control the sedimentation and theological behavior of colloidal tank wastes. First, the report describes the conditions under which the colloidal particles present in tank sludge are expected to aggregate. Computational models have been developed to predict solution conditions leading to agglomeration, and to predict the rate and size of aggregate growth. The models show that tank sludge should be heavily agglomerated under most baseline processing conditions. Second, the report describes models used to predict sedimentation rates and equilibrium sediment density profiles based on knowledge of agglomerate structures. The sedimentation models provide a self-consistent picture that explains the apparent discrepancies between bench-top experiments and tank-farm experience. Finally, both discrete and empirical models are presented that can be used to rationalize and predict the rheological properties of colloidal sludge suspensions. In all cases, model predictions are compared and contrasted with experimental results. The net results indicate that most of the observed behaviors of real sludges can be predicted, understood, and perhaps ultimately controlled by understanding a few key central concepts regarding agglomeration phenomena
Entry in the ADHD drugs market: Welfare impact of generics and me-toos
Recent decades have seen a growth in treatments for attention deficit hyperactivity disorder (ADHD) including many branded and generic drugs. In the early 2000's, new drug entry dramatically altered market shares. We estimate a demand system for ADHD drugs and assess the welfare impact of new drugs. We find that entry induced large welfare gains by reducing prices of substitute drugs, and by providing alternative delivery mechanisms for existing molecules. Our results suggest that the success of follow-on patented drugs may come from unanticipated innovations like delivery mechanisms, a factor ignored by proposals to retard new follow-on drug approvals
Preconceptional, Gestational, and Lactational Exposure to an Unconventional Oil and Gas Chemical Mixture Alters Energy Expenditure in Adult Female Mice
Previous studies conducted in our laboratory have found altered adult health outcomes in animals with prenatal exposure to environmentally relevant levels of unconventional oil and gas (UOG) chemicals with endocrine-disrupting activity. This study aimed to examine potential metabolic health outcomes following a preconception, prenatal and postnatal exposure to a mixture of 23 UOG chemicals. Prior to mating and from gestation day 1 to postnatal day 21, C57BL/6J mice were developmentally exposed to a laboratory-created mixture of 23 UOG chemicals in maternal drinking water. Body composition, spontaneous activity, energy expenditure, and glucose tolerance were evaluated in 7-month-old female offspring. Neither body weight nor body composition differed in 7-month female mice. However, females exposed to 1.5 and 150 Îźg/kg/day UOG mix had lower total and resting energy expenditure within the dark cycle. In the light cycle, the 1,500 Îźg//kg/day group had lower total energy expenditure and the 1.5 Îźg/kg/day group had lower resting energy expenditure. Females exposed to the 150 Îźg/kg/day group had lower spontaneous activity in the dark cycle, and females exposed to the 1,500 Îźg/kg/day group had lower activity in the light cycle. This study reports for the first time that developmental exposure to a mixture of 23 UOG chemicals alters energy expenditure and spontaneous activity in adult female mice
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COBRA-WC pretest predictions and post-test analysis of the FOTA temperature distribution during FFTF natural-circulation transients
The natural circulation tests of the Fast Flux Test Facility (FFTF) demonstrated a safe and stable transition from forced convection to natural convection and showed that natural convection may adequately remove decay heat from the reactor core. The COBRA-WC computer code was developed by the Pacific Northwest laboratory (PNL) to account for buoyancy-induced coolant flow redistribution and interassembly heat transfer, effects that become important in mitigating temperature gradients and reducing reactor core temperatures when coolant flow rate in the core is low. This report presents work sponsored by the US Department of Energy (DOE) with the objective of checking the validity of COBRA-WC during the first 220 seconds (sec) of the FFTF natural-circulation (plant-startup) tests using recorded data from two instrumented Fuel Open Test Assemblies (FOTAs). Comparison of COBRA-WC predictions of the FOTA data is a part of the final confirmation of the COBRA-WC methodology for core natural-convection analysis
The radio structure of ultra-high-energy synchrotron peak BL Lacs
We present the results of EVN and MERLIN 5 GHz observations of nine
ultra-high-energy synchrotron peak BL Lacs (UHBLs) selected as all BL Lacs with
\textbf{log (} from Nieppola et al.. The radio
structure was investigated for these sources, in combination with the available
VLBA archive data. We found that the core-jet structure is detected in five
sources, while four sources only have a compact core on pc scale. The core of
all sources shows high brightness temperature (with mean and median values
\textbf{log (}, which implies that the beaming
effect likely present in all sources. When the multi-epoch VLBI data are
available, we found no significant variations either for core or total flux
density in two sources (2E 0414+0057 and EXO 0706.1+5913), and no evident
proper motion in 2E 0414+0057, while the superluminal motion is likely detected
in EXO 0706.1+5913. Our sources are found to be less compact than the typical
HBLs in Giroletti et al, by comparing the ratio of the VLBI total flux to the
core flux at arcsec scale. Combining all our results, we propose that the
beaming effect might be present in the jets of UHBLs, however, it is likely
weaker than that of typical HBLs. Moreover, we found that UHBLs could be less
Doppler beamed versions of HBLs with similar jet power, by comparing the
distribution of redshift, and radio luminosities. The results are in good
consistence with the expectations from our previous work.Comment: 14 pages, 15 figures and 5 tables. Accepted by MNRA
Vortex pinning by natural defects in thin films of YBa2Cu3O7âδ
Although vortex pinning in laser-ablated YBa2Cu3O7âδ films on (100) SrTiO3 is dominated by threading dislocations, many other natural pinning sites are present. To identify the contribution from twin planes, surface corrugations and point defects, we manipulate the relative densities of all defects by post-annealing films with various as-grown dislocation densities, ndisl. While a universal magnetic field B dependence of the transport current density js(B, T) is observed (independently of ndisl, temperature T and the annealing treatment), the defect structure changes considerably. Correlating the microstructure to js(B, T), it becomes clear that surface roughness, twins and point defects are not important at low magnetic fields compared to linear defect pinning. Transmission electron microscopy indicates that threading dislocations are not part of grain boundaries nor are they related to the twin domain structure. We conclude that js(B, T) is essentially determined by pinning along threading dislocations, naturally induced during the growth process. Even in high magnetic fields, where the vortex density outnumbers ndisl, it appears that linear defects stabilize the vortex lattice by means of the vortexâvortex interaction.
Chandra Observations of 3C Radio Sources with z<0.3: Nuclei, Diffuse Emission, Jets and Hotspots
We report on our Chandra Cycle 9 program to observe half of the 60
(unobserved by Chandra) 3C radio sources at z<0.3 for 8 ksec each. Here we give
the basic data: the X-ray intensity of the nuclei and any features associated
with radio structures such as hot spots and knots in jets. We have measured
fluxes in soft, medium and hard bands and are thus able to isolate sources with
significant intrinsic column density. For the stronger nuclei, we have applied
the standard spectral analysis which provides the best fit values of X-ray
spectral index and column density. We find evidence for intrinsic absorption
exceeding a column density of 10^{22} cm^{-2} for one third of our sources.Comment: 12 pages, 37 figures (the complete version of the paper with all
figures is available on line, see appendix for details), ApJ accepte
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