8,001 research outputs found
Optimal strategies for regional cultivar testing
In undertaking cultivar trials, the variability of the response of the cultivars to the different environments in which they are grown introduces the possibility of release errors and nonârelease errors in the decisions made on the basis of the trial results. In this article a model is developed that accounts for the economic costs of those errors as well as the costs of operating the trials, and enables the features of the optimal cultivar testing program to be identified. The model is illustrated by application to wheat cultivar trials in central and southern NSW.Crop Production/Industries,
Mifepristone reduces insulin resistance in patient volunteers with adrenal incidentalomas that secrete low levels of cortisol : a pilot study
Background: Incidental adrenal masses are commonly detected during imaging for other pathologies. 10% of the elderly
population has an âadrenal incidentalomaâ, up to 20% of these show low-grade autonomous cortisol secretion and 60% of
patients with autonomous cortisol secretion have insulin resistance. Cortisol excess is known to cause insulin resistance, an
independent cardiovascular risk marker, however in patients with adrenal incidentalomas it is unknown whether their
insulin resistance is secondary to the excess cortisol and therefore potentially reversible. In a proof of concept study we
examined the short-term effects of glucocorticoid receptor (GR) antagonism in patients with an adrenal incidentaloma to
determine whether their insulin resistance was reversible.
Methodology/Principal Findings: In a prospective open-label pilot study, six individuals with adrenal incidentalomas and
autonomous cortisol secretion were treated with mifepristone (a GR antagonist) 200 mg twice daily and studied for 4 weeks
on a Clinical Research Facility. Insulin resistance at four weeks was assessed by insulin resistance indices, lnHOMA-IR and
lnMatsuda, and AUC insulin during a 2-hour glucose tolerance test. Biochemical evidence of GR blockade was shown in all
individuals and across the group there was a significant reduction in insulin resistance: lnHOMA-IR (1.0vs0.6; p = 0.03),
lnHOMA-%beta (4.8vs4.3; p = 0.03) and lnMatsuda (1.2vs1.6; p = 0.03). Five out of six individuals showed a reduction in
insulin AUC .7237 pmol/l.min, and in two patients this showed a clinically significant cardiovascular benefit (as defined by
the Helsinki heart study).
Conclusions: Short-term GR antagonism is sufficient to reduce insulin resistance in some individuals with adrenal
incidentalomas and mild cortisol excess. Further assessment is required to assess if the responses may be used to stratify
therapy as adrenal incidentalomas may be a common remediable cause of increased cardiovascular risk
Non-isotropy in the CMB power spectrum in single field inflation
Contaldi et al. [1] have suggested that an initial period of kinetic energy
domination in single field inflation may explain the lack of CMB power at large
angular scales. We note that in this situation it is natural that there also be
a spatial gradient in the initial value of the inflaton field, and that this
can provide a spatial asymmetry in the observed CMB power spectrum, manifest at
low multipoles. We investigate the nature of this asymmetry and comment on its
relation to possible anomalies at low multipoles.Comment: 25 pages, 12 figures. In this revised version, we include the
Integrated Sachs-Wolfe effect, which was missing from the original. This
modifies some results in the low multipoles. The comparison with experiment
is slightly better but the change is not statistically significan
Gait analysis in a <i>Mecp2</i> knockout mouse model of Rett syndrome reveals early-onset and progressive motor deficits
Rett syndrome (RTT) is a genetic disorder characterized by a range of features including cognitive impairment, gait abnormalities and a reduction in purposeful hand skills. Mice harbouring knockout mutations in the <i>Mecp2</i> gene display many RTT-like characteristics and are central to efforts to find novel therapies for the disorder. As hand stereotypies and gait abnormalities constitute major diagnostic criteria in RTT, it is clear that motor and gait-related phenotypes will be of importance in assessing preclinical therapeutic outcomes. We therefore aimed to assess gait properties over the prodromal phase in a functional knockout mouse model of RTT. In male <i>Mecp2</i> knockout mice, we observed alterations in stride, coordination and balance parameters at 4 weeks of age, before the onset of other overt phenotypic changes as revealed by observational scoring. These data suggest that gait measures may be used as a robust and early marker of <i>Mecp2</i>-dysfunction in future preclinical therapeutic studies
Factors affecting patient valuations of caries prevention:using and validating the willingness to pay method
Probing the Structure of the Pomeron
We suggest that the pseudo-rapidity cut dependence of diffractive deep-inelastic scattering events at HERA may provide a sensitive test of models of diffraction. A comparison with the experimental cross section shows that the Donnachie-Landshoff model and a simple two-gluon exchange model of the pomeron model are disfavoured. However a model with a direct coupling of the pomeron to quarks is viable for a harder quark--pomeron form factor, as is a model based on the leading-twist operator contribution. We also consider a direct-coupling scalar pomeron model. We comment on the implications of these results for the determination of the partonic structure of the pomeron.We suggest that the pseudo-rapidity cut dependence of diffractive deep-inelastic scattering events at HERA may provide a sensitive test of models of diffraction. A comparison with the experimental cross section shows that the Donnachie-Landshoff model and a simple two-gluon exchange model of the pomeron model are disfavoured. However a model with a direct coupling of the pomeron to quarks is viable for a harder quark--pomeron form factor, as is a model based on the leading-twist operator contribution. We also consider a direct-coupling scalar pomeron model. We comment on the implications of these results for the determination of the partonic structure of the pomeron
Anomalous Excitation Spectra of Frustrated Quantum Antiferromagnets
We use series expansions to study the excitation spectra of spin-1/2
antiferromagnets on anisotropic triangular lattices. For the isotropic
triangular lattice model (TLM) the high-energy spectra show several anomalous
features that differ strongly from linear spin-wave theory (LSWT). Even in the
Neel phase, the deviations from LSWT increase sharply with frustration, leading
to roton-like minima at special wavevectors. We argue that these results can be
interpreted naturally in a spinon language, and provide an explanation for the
previously observed anomalous finite-temperature properties of the TLM. In the
coupled-chains limit, quantum renormalizations strongly enhance the
one-dimensionality of the spectra, in agreement with experiments on Cs_2CuCl_4.Comment: 4 pages, 5 figures. New Fig. 3 with higher-order series data, paper
shortened, references updated, one added (Ref. 28), minor changes otherwise.
Published versio
The impact of General Dental Council registration and continuing professional development on UK dental care professionals:(2) dental technicians.
Excitation spectra of the spin-1/2 triangular-lattice Heisenberg antiferromagnet
We use series expansion methods to calculate the dispersion relation of the
one-magnon excitations for the spin-1/2 triangular-lattice nearest-neighbor
Heisenberg antiferromagnet above a three-sublattice ordered ground state.
Several striking features are observed compared to the classical (large-S)
spin-wave spectra. Whereas at low energies the dispersion is only weakly
renormalized by quantum fluctuations, significant anomalies are observed at
high energies. In particular, we find roton-like minima at special wave-vectors
and strong downward renormalization in large parts of the Brillouin zone,
leading to very flat or dispersionless modes. We present detailed comparison of
our calculated excitation energies in the Brillouin zone with the spin-wave
dispersion to order 1/S calculated recently by Starykh, Chubukov, and Abanov
[cond-mat/0608002]. We find many common features but also some quantitative and
qualitative differences. We show that at temperatures as low as 0.1J the
thermally excited rotons make a significant contribution to the entropy.
Consequently, unlike for the square lattice model, a non-linear sigma model
description of the finite-temperature properties is only applicable at
extremely low temperatures.Comment: 14 pages, 11 figure
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