15,395 research outputs found
Plasmon interactions in the quark-gluon plasma
Yang-Mills theory at finite temperature is rewritten as a theory of plasmons
which provides a Hamiltonian framework for perturbation theory with resummation
of hard thermal loops.Comment: 12 pages, LaTeX, minor typos corrected, discussion adde
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Comparison of the effects of high and low milk-replacer feeding regimens on health and growth of crossbred dairy heifers
Context: Pre-weaning growth in dairy heifers is highly dependent on the amount of milk fed. Both milk replacer (MR) and associated labour are costly, encouraging restricted milk rations and once-a-day feeding.
Aims: This study compared performance relating to the growth and health of calves receiving one of two commercial feeding regimens: High or Low.
Methods: All heifers born during the Spring (January–March) calving block on a commercial UK farm with mixed-breed genetics were recruited at birth, randomly assigned to the High (n = 104, receiving MR-A) or Low (n = 88, receiving MR-B) feed group and reared indoors on straw bedding, with free access to concentrate. Both groups initially received MR twice daily. The High group continued to receive MR twice daily throughout the experiment, whereas the Low group calves were reduced to a single MR feed daily during Weeks 4–8. Blood samples were taken in Weeks 1 and 6 to assess passive transfer and measure circulating insulin-like growth factor 1 (IGF1). The Wisconsin calf-scoring system was used to assess health of calves in Weeks 1, 2, 4, 6 and 8 and at 6 months and size was also measured at these times. Data were analysed by univariate and multivariate models.
Key results: Passive transfer was good in both groups (serum total protein (mean ± s.d.) 60.9 ± 9.1 mg/mL) with no differences in pre-weaning disease incidence; diarrhoea occurred in 64.5% and bovine respiratory disease in 26.3% of calves. High group calves were significantly heavier, taller and longer at all pre-weaning examinations except recruitment owing to more growth in the first month, and remained significantly larger at 6 months: weight 157 ± 8 vs 149 ± 7 kg, height 103 ± 5 vs 100 ± 5 cm, length 90 ± 4 vs 88 ± 5 cm. Plasma IGF1 concentrations at around Week 6 were doubled in the High group (101 ± 38.6 vs 55 ± 34.1 ng/mL). Bovine respiratory disease was associated with reduced weight gain. Heifers with diarrhoea were leaner at weaning. High feed group, weight at recruitment and good passive transfer were positively associated with weight at 6 months.
Conclusions: Higher feeding levels pre-weaning increased growth rates and IGF1, although the disease incidence was unaffected.
Implications: Previous studies have shown that more growth and higher IGF1 pre-weaning are associated with a lower age at first calving and an increased chance of reaching the end of first lactation. These in turn improve long-term performance
Fuzzy spaces and new random matrix ensembles
We analyze the expectation value of observables in a scalar theory on the
fuzzy two sphere, represented as a generalized hermitian matrix model. We
calculate explicitly the form of the expectation values in the large-N limit
and demonstrate that, for any single kind of field (matrix), the distribution
of its eigenvalues is still a Wigner semicircle but with a renormalized radius.
For observables involving more than one type of matrix we obtain a new
distribution corresponding to correlated Wigner semicircles.Comment: 12 pages, 1 figure; version to appear in Phys. Rev.
On the occurrence of sting-ray spines in the jaws and gills of the hammerhead shark Sphyrna zygaena (Linnaeus)
It is well-known that sharks ate voracious feeders and prey upon a wide variety of marine animals such as planktonic crustaceans, crabs,
molluscs, fishes, turtles and seals. White examining a specimen of Sphyrnra zygaena (Linnaeus) measuring 3'86 metres in total length (Photo I) which was caught off Tuticorin at 40 fathoms depth by long line on 22nd April, 1971, several spines of sting-rays were found in the
ja\vs and gills (Photo 2). The spines occurred in ooth jaws of S. 'Zygaena but most of them were found in the upper jaw and they were observed to have pierced the jaws and gills deeply
The Preparation of Aryl Thioethers by Reaction of Aromatic Halogen Compounds with Cuprous Thiophenolate or Cuprous Thiobutylate
The reaction of cuprous thiophenolate with an aryl halide in a mixture of quinoline and pyridine appears to be a general method for obtaini ng high yields of aryl thioethers. Only two halogen compounds were encountered which gave unexpected products. Cuprous thiobutylate will not react with inactivated aryl chlorides but readily with aryl bromides to replace the halogen atom with a butylmercapto group
Biexciton recombination rates in self-assembled quantum dots
The radiative recombination rates of interacting electron-hole pairs in a
quantum dot are strongly affected by quantum correlations among electrons and
holes in the dot. Recent measurements of the biexciton recombination rate in
single self-assembled quantum dots have found values spanning from two times
the single exciton recombination rate to values well below the exciton decay
rate. In this paper, a Feynman path-integral formulation is developed to
calculate recombination rates including thermal and many-body effects. Using
real-space Monte Carlo integration, the path-integral expressions for realistic
three-dimensional models of InGaAs/GaAs, CdSe/ZnSe, and InP/InGaP dots are
evaluated, including anisotropic effective masses. Depending on size, radiative
rates of typical dots lie in the regime between strong and intermediate
confinement. The results compare favorably to recent experiments and
calculations on related dot systems. Configuration interaction calculations
using uncorrelated basis sets are found to be severely limited in calculating
decay rates.Comment: 11 pages, 4 figure
Group memory rehabilitation for people with multiple sclerosis: a feasibility randomized controlled trial
Objective: To assess the feasibility and effectiveness of a group memory rehabilitation programme combining compensation and restitution strategies.
Design: Randomized controlled trial.
Setting: Community.
Participants: People with multiple sclerosis who reported memory difficulties were recruited.
Interventions: A group memory rehabilitation programme, comprising ten 1.5-hour sessions, was compared with a waiting list control.
Main measures: The primary outcome was the Everyday Memory Questionnaire. Secondary outcomes included the General Health Questionnaire 28 and MS Impact Scale administered four and eight months after randomization. In addition, those in the intervention group gave feedback about the intervention.
Results: Forty-eight participants were recruited. They were aged 34–72 years (mean 54.3, SD 11.0) and 33 (69%) were women. There were no significant differences between the two groups on the Everyday Memory Questionnaire or MS Impact Scale (P > 0.05) at four or eight months after randomization. However, the intervention group reported significantly better mood than controls on the GHQ-28 at eight months (P = 0.04). Participants showed minimal benefit from the memory rehabilitation programme on quantitative measures but the intervention was well received, as indicated by positive feedback at the end of the intervention.
Conclusions: There was no significant effect of the intervention on memory but there was a significant effect on mood. The results suggest a larger scale study is justified
Realising context-sensitive mobile messaging
Mobile technologies aim to assist people as they move from place to place going about their daily work and social routines. Established and very popular mobile technologies include short-text messages and multimedia messages with newer growing technologies including Bluetooth mobile data transfer protocols and mobile web access.Here we present new work which combines all of the above technologies to fulfil some of the predictions for future context aware messaging. We present a context sensitive mobile messaging system which derives context in the form of physical locations through location sensing and the co-location of people through Bluetooth familiarity
Carrier mobility and scattering lifetime in electric double-layer gated few-layer graphene
We fabricate electric double-layer field-effect transistor (EDL-FET) devices
on mechanically exfoliated few-layer graphene. We exploit the large capacitance
of a polymeric electrolyte to study the transport properties of three, four and
five-layer samples under a large induced surface charge density both above and
below the glass transition temperature of the polymer. We find that the carrier
mobility shows a strong asymmetry between the hole and electron doping regime.
We then employ ab-initio density functional theory (DFT) calculations to
determine the average scattering lifetime from the experimental data. We
explain its peculiar dependence on the carrier density in terms of the specific
properties of the electrolyte we used in our experiments.Comment: 6 pages, 3 figure
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