7,502 research outputs found
Hadronic contribution to the muon g-2: a theoretical determination
The leading order hadronic contribution to the muon g-2, , is
determined entirely from theory using an approach based on Cauchy's theorem in
the complex squared energy s-plane. This is possible after fitting the
integration kernel in with a simpler function of . The
integral determining in the light-quark region is then split
into a low energy and a high energy part, the latter given by perturbative QCD
(PQCD). The low energy integral involving the fit function to the integration
kernel is determined by derivatives of the vector correlator at the origin,
plus a contour integral around a circle calculable in PQCD. These derivatives
are calculated using hadronic models in the light-quark sector. A similar
procedure is used in the heavy-quark sector, except that now everything is
calculable in PQCD, thus becoming the first entirely theoretical calculation of
this contribution. Using the dual resonance model realization of Large
QCD to compute the derivatives of the correlator leads to agreement with the
experimental value of . Accuracy, though, is currently limited by the
model dependent calculation of derivatives of the vector correlator at the
origin. Future improvements should come from more accurate chiral perturbation
theory and/or lattice QCD information on these derivatives, allowing for this
method to be used to determine accurately entirely from theory,
independently of any hadronic model.Comment: Several additional clarifying paragraphs have been added. 1/N_c
corrections have been estimated. No change in result
Hypomagnesemia and increased risk of new-onset diabetes mellitus after transplantation in pediatric renal transplant recipients
Background: New onset diabetes after transplantation (NODAT) is a significant co-morbidity following kidney transplantation. Lower post-transplant serum magnesium levels have been found to be an independent risk factor for NODAT in adult kidney transplant recipients. / Methods: We undertook a retrospective analysis of risk factors for NODAT in pediatric renal transplant recipients at our institution with the aim of determining if hypomagnesemia confers a significant risk of developing NODAT in children. / Results: One hundred and seventy three children with median age at transplantation 7.0 (range: 1.3 – 17.5) years were included. Hypomagnesemia was a significant independent risk factor for NODAT (p = 0.01). High trough tacrolimus levels were also independently associated with NODAT (p < 0.001). There was no significant association between NODAT and children’s BMI at the time of transplantation, monthly cumulative steroid dose or post transplant CMV viremia (p = 0.9, 0.6 and 0.7 respectively). / Conclusions: This study identifies hypomagnesemia as a significant independent risk factor for developing NODAT in pediatric renal transplant recipients. Given the clear association between hypomagnesemia and NODAT in both adults and children following renal transplantation, further studies are merited to clarify the etiology of this association, and to examine the effect of magnesium supplementation on NODAT
Labelling and Diagnosis
This is the author accepted manuscript. The final version is available from the British Psychological SocietyGuest editoria
Quantum Spin Hall Effect and Enhanced Magnetic Response by Spin-Orbit Coupling
We show that the spin Hall conductivity in insulators is related with a
magnetic susceptibility representing the strength of the spin-orbit coupling.
We use this relationship as a guiding principle to search real materials
showing quantum spin Hall effect. As a result, we theoretically predict that
bismuth will show the quantum spin Hall effect, both by calculating the helical
edge states, and by showing the non-triviality of the Z_2 topological number,
and propose possible experiments.Comment: 5 pages, 2 figures, accepted for publication in Phys. Rev. Let
Mechanisms of growth inhibition of primary prostate epithelial cells following gamma irradiation or photodynamic therapy including senscence, necrosis, and autophagy, but not apoptosis
In comparison to more differentiated cells, prostate cancer stem-like cells are radioresistant, which could explain radio-recurrent prostate cancer. Improvement of radiotherapeutic efficacy may therefore require combination therapy. We have investigated the consequences of treating primary prostate epithelial cells with gamma irradiation and photodynamic therapy (PDT), both of which act through production of reactive oxygen species (ROS). Primary prostate epithelial cells were cultured from patient samples of benign prostatic hyperplasia and prostate cancer prior to treatment with PDT or gamma irradiation. Cell viability was measured using MTT and alamar blue assay, and cell recovery by colony-forming assays. Immunofluorescence of gamma-H2AX foci was used to quantify DNA damage, and autophagy and apoptosis were assessed using Western blots. Necrosis and senescence were measured by propidium iodide staining and beta-galactosidase staining, respectively. Both PDT and gamma irradiation reduced the colony-forming ability of primary prostate epithelial cells. PDT reduced the viability of all types of cells in the cultures, including stem-like cells and more differentiated cells. PDT induced necrosis and autophagy, whereas gamma irradiation induced senescence, but neither treatment induced apoptosis. PDT and gamma irradiation therefore inhibit cell growth by different mechanisms. We suggest these treatments would be suitable for use in combination as sequential treatments against prostate cancer
The IRAS 1-Jy Survey of Ultraluminous Infrared Galaxies: I. The sample and Luminosity Function
A complete flux-limited sample of 118 ultraluminous infrared galaxies (ULIGs)
has been identified from the IRAS Faint Source Catalog (FSC). The selection
criteria were a 60 micron flux density greater than 1 Jy in a region of the sky
delta > -40 deg, |b| > 30 deg. All sources were subsequently reprocessed using
coadded IRAS maps in order to obtain the best available flux estimates in all
four IRAS wavelength bands. The maximum observed infrared luminosity is L_ir =
10^{12.90} L_{sun}, and the maximum redshift is z = 0.268. The luminosity
function for ULIGs over the decade luminosity range L_ir = 10^{12} - 10^{13}
L_{sun} can be approximated by a power law Phi (L) ~= L^{-2.35} Mpc^{-3}
mag^{-1}. In the local Universe z < 0.1, the space density of ULIGs appears to
be comparable to or slightly larger than that of optically selected QSOs at
comparable bolometric luminosities. A maximum likelihood test suggests strong
evolution for our sample; assuming density evolution proportional to
(1+z)^{alpha} we find alpha = 7.6+/-3.2. Examination of the two-point
correlation function shows a barely significant level of clustering, xi (r) =
1.6 +/- 1.2, on size scales r ~= 22 h^{-1} Mpc.Comment: 18 pages of text, 10 pages of figures 1 to 6, 6 pages of tables 1 to
3, ApJS accepte
Extrapolating gravitational-wave data from numerical simulations
Two complementary techniques are developed for obtaining the asymptotic form
of gravitational-wave data at large radii from numerical simulations, in the
form of easily implemented algorithms. It is shown that, without extrapolation,
near-field effects produce errors in extracted waveforms that can significantly
affect LIGO data analysis. The extrapolation techniques are discussed in the
context of Newman--Penrose data applied to extrapolation of waveforms from an
equal-mass, nonspinning black-hole binary simulation. The results of the two
methods are shown to agree within error estimates. The various benefits and
deficiencies of the methods are discussed.Comment: Added missing references; refined data. Version accepted in Phys.
Rev.
Intra-session and inter-day reliability of the Myon 320 electromyography system during sub-maximal contractions
Electromyography systems are widely used within the field of scientific and clinical practices. The reliability of these systems are paramount when conducting research. The reliability of Myon 320 Surface Electromyography System is yet to be determined. This study aims to determine the intra-session and inter-day reliability of the Myon 320 Surface Electromyography System. Muscle activity from fifteen participants was measured at the anterior deltoid muscle during a bilateral front raise exercise, the vastus lateralis muscle during a squat exercise and the extensor carpi radialis brevis (ECRB) muscle during an isometric handgrip task. Intra-session and inter-day reliability was calculated by intraclass correlation coefficient, standard error of measurement and coefficient of variation (CV). The normalized root mean squared (RMS) surface electromyographic signals produced good intra-session and inter-day testing intraclass correlation coefficient values (range: 0.63-0.97) together with low standard error of measurement (range: 1.49-2.32) and CV (range: 95% Confidence Interval = 0.36-12.71) measures for the dynamic-and-isometric contractions. The findings indicate that the Myon 320 Surface Electromyography System produces good to fair reliability when examining intra-session and inter-day reliability. Findings of the study provide evidence of the reliability of electromyography between trials which is essential during clinical testing.</p
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