3,215 research outputs found
Ram pressure drag - the effects of ram pressure on dark matter and stellar disk dynamics
We investigate the effects of ram pressure stripping on gas-rich disk
galaxies in the cluster environment. Ram pressure stripping principally effects
the atomic gas in disk galaxies, stripping away outer disk gas to a truncation
radius. We demonstrate that the drag force exerted on truncated gas disks is
passed to the stellar disk, and surrounding dark matter through their mutual
gravity. Using a toy model of ram pressure stripping, we show that this can
drag a stellar disk and dark matter cusp off centre within it's dark matter
halo by several kiloparsecs. We present a simple analytical description of this
process that predicts the drag force strength and its dependency on ram
pressures and disk galaxy properties to first order. The motion of the disk can
result in temporary deformation of the stellar disk. However we demonstrate
that the key source of stellar disk heating is the removal of the gas potential
from within the disk. This can result in disk thickening by approximately a
factor of two in gas-rich disks.Comment: Accepted by MNRAS (Oct 2011) 17 pages, 11 figures, 1 tabl
Factors Influencing The Practice Of Exclusive Breastfeeding In Three Regions Of Nigeria
Background: Breastfeeding is the super food for babies and is sufficient if given exclusively in the first six months of a baby's life. In Nigeria, the practice of breastfeeding is high but Exclusive Breastfeeding (EBF) rates remain low at 13%. Several interrelating factors directly or indirectly affect the decision or ability of mothers to practice EBF. The objective of this study was to assess the factors influencing EBF in Nigeria.Methodology: A cross sectional survey among 433 mothers of children between six and twenty-four months old was conducted in urban and peri-urban/rural parts of Zaria, Abakaliki, and Ibadan. The study adopted a mixed research methodology that consisted of key informant interviews, structured questionnaires, and focus group discussions. Descriptive statistic was used to analyze the quantitative data while the themes in the qualitative data were analyzed using manual content analysis.Results: Approximately 90% of all mothers interviewed had heard about EBF, although with variations in the exact definition of EBF as many interpreted it to be just till the start of 6 months. The practice of EBF is low - Ibadan (16%), Abakaliki (10%) and Zaria (2%).Inaccurate knowledge of EBF, occupation, antenatal care attendance, age of mothers, supportive environment from stakeholders are some factors associated with the practice of EBF.Conclusion: The findings in this study indicate that several factors affect the practice of EBF in Nigeria. Improving the practice of EBF in the country will require a multifaceted approach and concerted efforts from stakeholders to address the deterring factors limiting its practice.Keywords: Exclusive Breastfeeding, Interrelating factors, social activity and significant others, and Nigeri
Decoherence induced deformation of the ground state in adiabatic quantum computation
Despite more than a decade of research on adiabatic quantum computation
(AQC), its decoherence properties are still poorly understood. Many theoretical
works have suggested that AQC is more robust against decoherence, but a
quantitative relation between its performance and the qubits' coherence
properties, such as decoherence time, is still lacking. While the thermal
excitations are known to be important sources of errors, they are predominantly
dependent on temperature but rather insensitive to the qubits' coherence. Less
understood is the role of virtual excitations, which can also reduce the ground
state probability even at zero temperature. Here, we introduce normalized
ground state fidelity as a measure of the decoherence-induced deformation of
the ground state due to virtual transitions. We calculate the normalized
fidelity perturbatively at finite temperatures and discuss its relation to the
qubits' relaxation and dephasing times, as well as its projected scaling
properties.Comment: 10 pages, 3 figure
The Debrisoft ® monofilament debridement pad for use in acute or chronic wounds: A NICE medical technology guidance
As part of its Medical Technology Evaluation Programme, the National Institute for Health and Care Excellence (NICE) invited a manufacturer to provide clinical and economic evidence for the evaluation of the Debrisoft ® monofilament debridement pad for use in acute or chronic wounds. The University of Birmingham and Brunel University, acting as a consortium, was commissioned to act as an External Assessment Centre (EAC) for NICE, independently appraising the submission. This article is an overview of the original evidence submitted, the EAC’s findings and the final NICE guidance issued. The sponsor submitted a simple cost analysis to estimate the costs of using Debrisoft® to debride wounds compared with saline and gauze, hydrogel and larvae. Separate analyses were conducted for applications in home and applications in a clinic setting. The analysis took an UK National Health Service (NHS) perspective. It incorporated the costs of the technologies and supplementary technologies (such as dressings) and the costs of their application by a district nurse. The sponsor concluded that Debrisoft® was cost saving relative to the comparators. The EAC made amendments to the sponsor analysis to correct for errors and to reflect alternative assumptions. Debrisoft® remained cost saving in most analyses and savings ranged from £77 to £222 per patient compared with hydrogel, from £97 to £347 compared with saline and gauze, and from £180 to £484 compared with larvae depending on the assumptions included in the analysis and whether debridement took place in a home or clinic setting. All analyses were severely limited by the available data on effectiveness, in particular a lack of comparative studies and that the effectiveness data for the comparators came from studies reporting different clinical endpoints compared with Debrisoft®. The Medical Technologies Advisory Committee made a positive recommendation for adoption of Debrisoft® and this has been published as a NICE medical technology guidance (MTG17).The Birmingham and Brunel Consortium is funded by NICE to act as an External Assessment Centre for the Medical Technologies Evaluation Programme
Vegetation and the importance of insecticide-treated target siting for control of Glossina fuscipes fuscipes
Control of tsetse flies using insecticide-treated targets is often hampered by vegetation re-growth and encroachment which obscures a target and renders it less effective. Potentially this is of particular concern for the newly developed small targets (0.25 high × 0.5 m wide) which show promise for cost-efficient control of Palpalis group tsetse flies. Consequently the performance of a small target was investigated for Glossina fuscipes fuscipes in Kenya, when the target was obscured following the placement of vegetation to simulate various degrees of natural bush encroachment. Catches decreased significantly only when the target was obscured by more than 80%. Even if a small target is underneath a very low overhanging bush (0.5 m above ground), the numbers of G. f. fuscipes decreased by only about 30% compared to a target in the open. We show that the efficiency of the small targets, even in small (1 m diameter) clearings, is largely uncompromised by vegetation re-growth because G. f. fuscipes readily enter between and under vegetation. The essential characteristic is that there should be some openings between vegetation.
This implies that for this important vector of HAT, and possibly other Palpalis group flies, a smaller initial clearance zone around targets can be made and longer interval between site maintenance visits is possible both of which will result in cost savings for large scale operations. We also investigated and discuss other site features e.g. large solid objects and position in relation to the water's edge in terms of the efficacy of the small targets
Star-galaxy separation in the AKARI NEP Deep Field
Context: It is crucial to develop a method for classifying objects detected
in deep surveys at infrared wavelengths. We specifically need a method to
separate galaxies from stars using only the infrared information to study the
properties of galaxies, e.g., to estimate the angular correlation function,
without introducing any additional bias. Aims. We aim to separate stars and
galaxies in the data from the AKARI North Ecliptic Pole (NEP) Deep survey
collected in nine AKARI / IRC bands from 2 to 24 {\mu}m that cover the near-
and mid-infrared wavelengths (hereafter NIR and MIR). We plan to estimate the
correlation function for NIR and MIR galaxies from a sample selected according
to our criteria in future research. Methods: We used support vector machines
(SVM) to study the distribution of stars and galaxies in the AKARIs multicolor
space. We defined the training samples of these objects by calculating their
infrared stellarity parameter (sgc). We created the most efficient classifier
and then tested it on the whole sample. We confirmed the developed separation
with auxiliary optical data obtained by the Subaru telescope and by creating
Euclidean normalized number count plots. Results: We obtain a 90% accuracy in
pinpointing galaxies and 98% accuracy for stars in infrared multicolor space
with the infrared SVM classifier. The source counts and comparison with the
optical data (with a consistency of 65% for selecting stars and 96% for
galaxies) confirm that our star/galaxy separation methods are reliable.
Conclusions: The infrared classifier derived with the SVM method based on
infrared sgc- selected training samples proves to be very efficient and
accurate in selecting stars and galaxies in deep surveys at infrared
wavelengths carried out without any previous target object selection.Comment: 8 pages, 8 figure
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