539 research outputs found
Structure, Biochemistry and Comparative Aspects of Mammalian Seminal Plasma Acrosin Inhibitors
SN 2013df, a double-peaked IIb supernova from a compact progenitor and an extended H envelope
Optical observations of the type IIb SN 2013df from a few days to about 250
days after explosion are presented. These observations are complemented with UV
photometry taken by \textit{SWIFT} up to 60 days post-explosion. The
double-peak optical light curve is similar to those of SNe 1993J and 2011fu
although with different decline and rise rates. From the modelling of the
bolometric light curve, we have estimated that the total mass of synthesised
Ni in the explosion is M, while the ejecta mass is
M and the explosion energy erg. In
addition, we have estimated a lower limit to the progenitor radius ranging from
. The spectral evolution indicates that SN 2013df had a
hydrogen envelope similar to SN 1993J ( M). The line
profiles in nebular spectra suggest that the explosion was asymmetric with the
presence of clumps in the ejecta, while the [O\,{\sc i}]
, luminosities, may indicate that the progenitor
of SN 2013df was a relatively low mass star ( M).Comment: 18 pages, 11 figures, 9 tables, accepted for publication in MNRA
Sonoelastography of the Common Flexor Tendon of the Elbow with Histologic Agreement: A Cadaveric Study.
Purpose To determine the correlation of the results of conventional B-mode ultrasonography (US) and compression sonoelastography with histologic results in common flexor tendons of the elbow in human cadavers. Materials and Methods Twenty-five common flexor tendons were evaluated in 16 fresh, unembalmed cadavers of 11 women with a median age of 85 years (range, 71-101 years) and five men with a median age of 78 years (range, 70-88 years). Informed consent was provided according to the last will of the donors. B-mode US results were classified as grade 1, normal tendon with homogeneous fibrillar pattern; grade 2, tendon thickening or hypoechoic areas and/or calcifications in less than 30% of the tendon; or grade 3, hypoechoic areas and/or calcifications greater than 30% of the tendon. Sonoelastographic results were grade 1, blue (hardest) to green (hard); grade 2, yellow (soft); and grade 3, red (softest). The intraclass correlation coefficient was calculated to determine agreement with histologic findings for each B-mode US, sonoelastographic, and combined B-mode US and sonoelastographic examination. Histologic results were grade 1, normal, with parallel fibrillar pattern; grade 2, mild tendinopathy, with cellular infiltration, angiogenesis, or fatty vacuoles; or grade 3, severe tendinopathy, with loss of parallel collagen structure and necrosis. Results Histologic alterations were detected in 44% (11 of 25) of biopsy specimens. Intraclass correlation with histologic results was 0.57 for B-mode US, 0.68 for sonoelastography, and 0.84 for the combination of the two approaches. Conclusion The addition of sonoelastography to B-mode US provided statistically significant improvement in correlation with histologic results compared with the use of B-mode US alone (P \u3c .02). (©) RSNA, 2016 Online supplemental material is available for this article
Theory of excitons in cubic III-V semiconductor GaAs, InAs and GaN quantum dots: fine structure and spin relaxation
Exciton fine structures in cubic III-V semiconductor GaAs, InAs and GaN
quantum dots are investigated systematically and the exciton spin relaxation in
GaN quantum dots is calculated by first setting up the effective exciton
Hamiltonian. The electron-hole exchange interaction Hamiltonian, which consists
of the long- and short-range parts, is derived within the effective-mass
approximation by taking into account the conduction, heavy- and light-hole
bands, and especially the split-off band. The scheme applied in this work
allows the description of excitons in both the strong and weak confinement
regimes. The importance of treating the direct electron-hole Coulomb
interaction unperturbatively is demonstrated. We show in our calculation that
the light-hole and split-off bands are negligible when considering the exciton
fine structure, even for GaN quantum dots, and the short-range exchange
interaction is irrelevant when considering the optically active doublet
splitting. We point out that the long-range exchange interaction, which is
neglected in many previous works, contributes to the energy splitting between
the bright and dark states, together with the short-range exchange interaction.
Strong dependence of the optically active doublet splitting on the anisotropy
of dot shape is reported. Large doublet splittings up to 600 eV, and even
up to several meV for small dot size with large anisotropy, is shown in GaN
quantum dots. The spin relaxation between the lowest two optically active
exciton states in GaN quantum dots is calculated, showing a strong dependence
on the dot anisotropy. Long exciton spin relaxation time is reported in GaN
quantum dots. These findings are in good agreement with the experimental
results.Comment: 22+ pages, 16 figures, several typos in the published paper are
corrected in re
Detection of vascularity in wrist tenosynovitis: power doppler ultrasound compared with contrast-enhanced grey-scale ultrasound
Brain connectivity alterations in early psychosis: from clinical to neuroimaging staging.
Early in the course of psychosis, alterations in brain connectivity accompany the emergence of psychiatric symptoms and cognitive impairments, including processing speed. The clinical-staging model is a refined form of diagnosis that places the patient along a continuum of illness conditions, which allows stage-specific interventions with the potential of improving patient care and outcome. This cross-sectional study investigates brain connectivity features that characterize the clinical stages following a first psychotic episode. Structural brain networks were derived from diffusion-weighted MRI for 71 early-psychosis patients and 76 healthy controls. Patients were classified into stage II (first-episode), IIIa (incomplete remission), IIIb (one relapse), and IIIc (two or more relapses), according to the course of the illness until the time of scanning. Brain connectivity measures and diffusion parameters (fractional anisotropy, apparent diffusion coefficient) were investigated using general linear models and sparse linear discriminant analysis (sLDA), studying distinct subgroups of patients who were at specific stages of early psychosis. We found that brain connectivity impairments were more severe in clinical stages following the first-psychosis episode (stages IIIa, IIIb, IIIc) than in first-episode psychosis (stage II) patients. These alterations were spatially diffuse but converged on a set of vulnerable regions, whose inter-connectivity selectively correlated with processing speed in patients and controls. The sLDA suggested that relapsing-remitting (stages IIIb, IIIc) and non-remitting (stage IIIa) patients are characterized by distinct dysconnectivity profiles. Our results indicate that neuroimaging markers of brain dysconnectivity in early psychosis may reflect the heterogeneity of the illness and provide a connectomics signature of the clinical-staging model
The radial and ulnar collateral ligaments of the wrist are true ligaments
PURPOSEOur hypothesis in this study is that the radial and ulnar collateral ligaments of the wrist exist and are true ligaments which can be visualized by high-resolution ultrasonography (US).METHODSHigh-resolution US examination of the radial and ulnar collateral ligaments of the wrist was performed on 56 fresh cadaveric wrists. The visibility of these ligaments was assessed by four observers who classified the ligaments in consensus as well seen, adequately seen, or not seen. Surgical dissections of 12 radial collateral ligaments and 12 ulnar collateral ligaments were then performed and the ligaments were classified as present or absent. The US and dissection results were then compared. To confirm that the dissected structures represent true ligaments a histologic examination of the ligaments was performed.RESULTSRESULTSAll examined radial and ulnar collateral ligaments were seen on the US examination. The radial collateral ligament was seen between the radial styloid and radial aspect of the scaphoid. The ulnar collateral ligament was seen between ulnar styloid process and the triquetrum. On all surgical dissections, the radial collateral ligament was present at the floor of the first extensor compartment and the ulnar collateral ligament was at the floor of the sixth extensor compartment. Both ligaments were proven to be true capsular ligaments on both dissection and histologic examinations.CONCLUSIONThe radial and ulnar collateral ligaments of the wrist are true ligaments and can be seen at the floor of the first and the sixth extensor compartments, respectively, using high-resolution US. Based on their anatomic location, they most likely provide static stability to the wrist joint
Equipment specification for a space rated radar altimeter Final technical report
Equipment specifications for GEOS C mission altimeter
Swapping and entangling hyperfine coupled nuclear spin baths
We numerically study the hyperfine induced nuclear spin dynamics in a system
of two coupled quantum dots in zero magnetic field. Each of the electron spins
is considered to interact with an individual bath of nuclear spins via
homogeneous coupling constants (all coupling coefficients being equal). In
order to lower the dimension of the problem, the two baths are approximated by
two single long spins. We demonstrate that the hyperfine interaction enables to
utilize the nuclear baths for quantum information purposes. In particular, we
show that it is possible to swap the nuclear ensembles on time scales of
seconds and indicate that it might even be possible to fully entangle them. As
a key result, it turns out that the larger the baths are, the more useful they
become as a resource of quantum information. Interestingly, the nuclear spin
dynamics strongly benefits from combining two quantum dots of different
geometry to a double dot set up.Comment: 6 pages, 7 figure
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