7,354 research outputs found
Inclusion of non-spherical components of the Pauli blocking operator in (p,p') reactions
We present the first calculations of proton elastic and inelastic scattering
in which the Pauli blocking operator contains the leading non-spherical
components as well as the usual spherical (angle-averaged) part. We develop a
formalism for including the contributions to the effective nucleon-nucleon
interaction from the resulting new G-matrix elements that extend the usual
two-nucleon spin structure and may not conserve angular momentum. We explore
the consequences of parity conservation, time reversal invariance, and
nucleon-nucleon antisymmetrization for the new effective interaction. Changes
to the calculated cross section and spin observables are small in the energy
range from 100 to 200 MeV.Comment: 24 pages, 4 figures, to be published in Physical Review
Efficient Hadronic Operators in Lattice Gauge Theory
We study operators to create hadronic states made of light quarks in quenched
lattice gauge theory. We construct non-local gauge-invariant operators which
provide information about the spatial extent of the ground state and excited
states. The efficiency of the operators is shown by looking at the wave
function of the first excited state, which has a node as a function of the
spatial extent of the operator. This allows one to obtain an uncontaminated
ground state for hadrons.Comment: 18 pages, Latex text, followed by 11 postscript figures in
self-unpacking file. Also available at
ftp://suna.amtp.liv.ac.uk/pub/cmi/wavefn
A Model for the Analysis of Caries Occurrence in Primary Molar Tooth Surfaces
Recently methods of caries quantification in the primary dentition have moved away from summary ‘whole mouth’ measures at the individual level to methods based on generalised linear modelling (GLM) approaches or survival analysis approaches. However, GLM approaches based on logistic transformation fail to take into account the time-dependent process of tooth/surface survival to caries. There may also be practical difficulties associated with casting parametric survival-based approaches in a complex multilevel hierarchy and the selection of an optimal survival distribution, while non-parametric survival methods are not generally suitable for the assessment of supplementary information recorded on study participants. In the current investigation, a hybrid semi-parametric approach comprising elements of survival-based and GLM methodologies suitable for modelling of caries occurrence within fixed time periods is assessed, using an illustrative multilevel data set of caries occurrence in primary molars from a cohort study, with clustering of data assumed to occur at surface and tooth levels. Inferences of parameter significance were found to be consistent with previous parametric survival-based analyses of the same data set, with gender, socio-economic status, fluoridation status, tooth location, surface type and fluoridation status-surface type interaction significantly associated with caries occurrence. The appropriateness of the hierarchical structure facilitated by the hybrid approach was also confirmed. Hence the hybrid approach is proposed as a more appropriate alternative to primary caries modelling than non-parametric survival methods or other GLM-based models, and as a practical alternative to more rigorous survival-based methods unlikely to be fully accessible to most researchers
Sexually transmitted infection risk exposure among black and minority ethnic youth in northwest London: findings from a study translating a sexually transmitted infection risk-reduction intervention to the UK setting.
OBJECTIVES: Young black women are disproportionately affected by sexually transmitted infections (STI) in the UK, but effective interventions to address this are lacking. The Young Brent Project explored the nature and context of sexual risk-taking in young people to inform the translation of an effective clinic-based STI reduction intervention (Project SAFE) from the USA to the UK. METHODS: One-to-one in-depth interviews (n = 37) and group discussions (n = 10) were conducted among men and women aged 15-27 years from different ethnic backgrounds recruited from youth and genitourinary medicine clinic settings in Brent, London. The interviews explored the context within which STI-related risks were assessed, experienced and avoided, the skills needed to recognise risk and the barriers to behaviour change. RESULTS: Concurrent sexual partnerships, mismatched perceptions and expectations, and barriers to condom use contributed to STI risk exposure and difficulties in implementing risk-reduction strategies. Women attempted to achieve monogamy, but experienced complex and fluid sexual relationships. Low risk awareness, flawed partner risk assessments, negative perceptions of condoms and lack of control hindered condom use. Whereas men made conscious decisions, women experienced persuasion, deceit and difficulty in requesting condom use, particularly with older partners. CONCLUSIONS: Knowledge of STI and condom use skills is not enough to equip young people with the means to reduce STI risk. Interventions with young women need to place greater emphasis on: entering and maintaining healthy relationships; awareness of risks attached to different forms of concurrency and how concurrency arises; skills to redress power imbalances and building self-esteem
Study of Space Station propulsion system resupply and repair Final report
Resupply and repair capabilities for orbital space station bipropellant propulsion syste
Hemocytes are essential for Drosophila melanogaster post-embryonic development, independent of control of the microbiota
Proven roles for hemocytes (blood cells) have expanded beyond the control of infections in Drosophila. Despite this, the crucial role of hemocytes in post-embryonic development has long thought to be limited to control of microorganisms during metamorphosis. This has previously been shown by rescue of adult development in hemocyte-ablation models under germ-free conditions. Here, we show that hemocytes have an essential role in post-embryonic development beyond their ability to control the microbiota. Using a newly generated strong hemocyte-specific driver line for the GAL4/UAS system, we show that specific ablation of hemocytes is early pupal lethal, even under axenic conditions. Genetic rescue experiments prove that this is a hemocyte-specific phenomenon. RNA-seq data suggests that dysregulation of the midgut is a prominent consequence of hemocyte ablation in larval stages, resulting in reduced gut lengths. Dissection suggests that multiple processes may be affected during metamorphosis. We believe this previously unreported role for hemocytes during metamorphosis is a major finding for the field
The Hyperfine Splitting in Charmonium: Lattice Computations Using the Wilson and Clover Fermion Actions
We compute the hyperfine splitting on the lattice,
using both the Wilson and -improved (clover) actions for quenched quarks.
The computations are performed on a lattice at ,
using the same set of 18 gluon configurations for both fermion actions. We find
that the splitting is 1.83\err{13}{15} times larger with the clover action than
with the Wilson action, demonstrating the sensitivity of the spin-splitting to
the magnetic moment term which is present in the clover action. However, even
with the clover action the result is less than half of the physical
mass-splitting. We also compute the decay constants and
, both of which are considerably larger when computed using
the clover action than with the Wilson action. For example for the ratio
we find 0.32\err{1}{2} with the Wilson action
and with the clover action (the physical value is 0.44(2)).Comment: LaTeX file, 8 pages and two postscript figures. Southampton Preprint:
SHEP 91/92-27 Edinburgh Preprint: 92/51
Hemocytes are essential for Drosophila melanogaster post-embryonic development, independent of control of the microbiota.
Proven roles for hemocytes (blood cells) have expanded beyond the control of infections in Drosophila. Despite this, the crucial role of hemocytes in post-embryonic development has long thought to be limited to control of microorganisms during metamorphosis. This has previously been shown by rescue of adult development in hemocyte-ablation models under germ-free conditions. Here, we show that hemocytes have an essential role in post-embryonic development beyond their ability to control the microbiota. Using a newly generated strong hemocyte-specific driver line for the GAL4/UAS system, we show that specific ablation of hemocytes is early pupal lethal, even under axenic conditions. Genetic rescue experiments prove that this is a hemocyte-specific phenomenon. RNA-seq data suggests that dysregulation of the midgut is a prominent consequence of hemocyte ablation in larval stages, resulting in reduced gut lengths. Dissection suggests that multiple processes may be affected during metamorphosis. We believe this previously unreported role for hemocytes during metamorphosis is a major finding for the field
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