1,174 research outputs found
Use of the distorted wave Born approximation to predict scattering by inhomogeneous objects : application to squid
Author Posting. © Acoustical Society of America, 2009. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 125 (2009): 73-88, doi:10.1121/1.3021298.A new method has been developed to predict acoustic scattering by weakly scattering objects with three-dimensional variability in sound speed and density. This variability can take the form of inhomogeneities within the body of the scatterer and/or geometries where the acoustic wave passes through part of the scattering body, into the surrounding medium, and back into the body. This method applies the distorted wave Born approximation (DWBA) using a numerical approach that rigorously accounts for the phase changes within a scattering volume. Ranges of validity with respect to material properties and numerical considerations are first explored through comparisons with modal-series-based predictions of scattering by fluid-filled spherical and cylindrical fluid shells. The method is then applied to squid and incorporates high resolution spiral computerized tomography (SCT) scans of the complex morphology of the organism. Target strength predictions based on the SCT scans are compared with published backscattering data from live, freely swimming and tethered squid. The new method shows significant improvement for both single-orientation and orientation-averaged scattering predictions over the DWBA-homogeneous-prolate-spheroid model
What's new in atopic eczema? An analysis of systematic reviews published in 2015. Part 2: prevention and treatment
This review forms part of a series of annual updates that summarize the evidence base for atopic eczema (AE), providing a succinct guide for clinicians and patients. It provides a summary of key findings from 26 systematic reviews that were published during 2015, and focuses on the treatment and prevention of AE. For systematic reviews on the epidemiology and methodological issues, see Part 1 of this update. Topical corticosteroid withdrawal syndrome, ‘steroid addiction’, has been evaluated in a high‐quality systematic review, which helps better define this entity and the risk factors for it. A Cochrane Review has not demonstrated any association between topical corticosteroid use in pregnancy and adverse outcomes, although very large quantities of potent/very potent topical corticosteroids may be associated with reduced birth weight. House dust mite avoidance strategies do not appear to prevent AE. Exposure to probiotics prenatally and in early infancy may help prevent AE, but there is no evidence that maternal diet or supplementation has a preventative effect
11 beta-hydroxysteroid dehydrogenase type 1 regulates glucocorticoid-induced insulin resistance in skeletal muscle
OBJECTIVE: Glucocorticoid excess is characterized by increased adiposity, skeletal myopathy, and insulin resistance, but the precise molecular mechanisms are unknown. Within skeletal muscle, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts cortisone (11-dehydrocorticosterone in rodents) to active cortisol (corticosterone in rodents). We aimed to determine the mechanisms underpinning glucocorticoid-induced insulin resistance in skeletal muscle and indentify how 11beta-HSD1 inhibitors improve insulin sensitivity. \ud
RESEARCH DESIGN AND METHODS: Rodent and human cell cultures, whole-tissue explants, and animal models were used to determine the impact of glucocorticoids and selective 11beta-HSD1 inhibition upon insulin signaling and action. \ud
RESULTS: Dexamethasone decreased insulin-stimulated glucose uptake, decreased IRS1 mRNA and protein expression, and increased inactivating pSer insulin receptor substrate (IRS)-1. 11beta-HSD1 activity and expression were observed in human and rodent myotubes and muscle explants. Activity was predominantly oxo-reductase, generating active glucocorticoid. A1 (selective 11beta-HSD1 inhibitor) abolished enzyme activity and blocked the increase in pSer IRS1 and reduction in total IRS1 protein after treatment with 11DHC but not corticosterone. In C57Bl6/J mice, the selective 11beta-HSD1 inhibitor, A2, decreased fasting blood glucose levels and improved insulin sensitivity. In KK mice treated with A2, skeletal muscle pSer IRS1 decreased and pThr Akt/PKB increased. In addition, A2 decreased both lipogenic and lipolytic gene expression.\ud
CONCLUSIONS: Prereceptor facilitation of glucocorticoid action via 11beta-HSD1 increases pSer IRS1 and may be crucial in mediating insulin resistance in skeletal muscle. Selective 11beta-HSD1 inhibition decreases pSer IRS1, increases pThr Akt/PKB, and decreases lipogenic and lipolytic gene expression that may represent an important mechanism underpinning their insulin-sensitizing action
Evaluation of a Vancomycin Dosing Protocol and Pharmacokinetic Parameters in Burn Patients
Published abstract from the 47th American Burn Association Annual Meeting. Chicago, IL April 2015
Classification of broadband echoes from prey of a foraging Blainville's beaked whale
Author Posting. © Acoustical Society of America, 2008. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 123 (2008): 1753-1762, doi:10.1121/1.2828210.Blainville's beaked whales (Mesoplodon densirostris) use broadband, ultrasonic echolocation signals with a −10 dB bandwidth from 26 to 51 kHz to search for, localize, and approach prey that generally consist of mid-water and deep-water fishes and squid. Although it is well known that the spectral characteristics of broadband echoes from marine organisms vary as a function of size, shape, orientation, and anatomical group, there is little evidence as to whether or not free-ranging toothed whales use spectral cues in discriminating between prey and nonprey. In order to study the prey-classification process, a stereo acoustic tag was deployed on a Blainville's beaked whale so that emitted clicks and the corresponding echoes from targets in the water could be recorded. A comparison of echoes from targets apparently selected by the whale and those from a sample of scatterers that were not selected suggests that spectral features of the echoes, target strengths, or both may have been used by the whale to discriminate between echoes. Specifically, the whale appears to favor targets with one or more nulls in the echo spectra and to seek prey with higher target strengths at deeper depths.Field work was supported by the U.S. National
Oceanographic Partnership Program, the U.S. Office of Naval
Research, and the Canary Islands government.
Analysis of the data was supported by the Office
of the Oceanographer of the U.S. Navy, The Academic Programs
Office at the Woods Hole Oceanographic Institution
and the Danish Natural Science Research Council through a
Steno scholarship to Peter T. Madsen
GMRT Detection of HI 21 cm-line Absorption from the Peculiar Galaxy in Abell 2125
Using the recently completed Giant Meterwave Radio Telescope, we have
detected the HI 21 cm-line absorption from the peculiar galaxy C153 in the
galaxy cluster Abell 2125. The HI absorption is at a redshift of 0.2533, with a
peak optical depth of 0.36. The full width at half minimum of the absorption
line is 100 km/s. The estimated column density of atomic Hydrogen is
0.7e22(Ts/100K) per sq. cm. The HI absorption is redshifted by ~ 400 km/s
compared to the [OIII] emission line from this system. We attribute this to an
in-falling cold gas, or to an out-flowing ionised gas, or to a combination of
both as a consequence of tidal interactions of C153 with either a cluster
galaxy or the cluster potential.Comment: 9 pages, 2 figures, uses jaa.sty (included
The dynamics of S0 galaxies and their Tully-Fisher relation
This paper investigates the detailed dynamical properties of a relatively
homogeneous sample of disc-dominated S0 galaxies, with a view to understanding
their formation, evolution and structure. By using high signal-to-noise ratio
long-slit spectra of edge-on systems, we have been able to reconstruct the
complete line-of-sight velocity distributions of stars along the galaxies'
major axes. From these data, we have derived both model distribution functions
(the phase density of their stars) and the approximate form of their
gravitational potentials. The derived distribution functions are all consistent
with these galaxies being simple disc systems, with no evidence for a complex
formation history. Essentially no correlation is found between the
characteristic mass scale-lengths and the photometric scale-lengths in these
galaxies, suggesting that they are dark-matter dominated even in their inner
parts. Similarly, no correlation is found between the mass scale-lengths and
asymptotic rotation speed, implying a wide range of dark matter halo
properties. By comparing their asymptotic rotation speeds with their absolute
magnitudes, we find that these S0 galaxies are systematically offset from the
Tully-Fisher relation for later-type galaxies. The offset in luminosity is what
one would expect if star formation had been suddenly switched off a few Gyrs
ago, consistent with a simple picture in which these S0s were created from
ordinary later-type spirals which were stripped of their star-forming ISM when
they encountered a dense cluster environment.Comment: 8 pages, 16 figures, accepted by MNRA
Optical and digital phase conjugation techniques for fiber nonlinearity compensation
We discuss recent progress on the use of optical and digital phase conjugation techniques for nonlinearity compensation in optical fiber links. We compare the achievable performance gain of phase conjugated twin wave applied in two polarization states and time segments with mid-link optical phase conjugation and digital back propagation. For multicarrier transmission scheme such as orthogonal frequency division multiplexing, two recently proposed schemes, namely phase-conjugated pilots and phase-conjugated subcarrier coding are reviewed
11 beta-hydroxysteroid dehydrogenase type 1 regulates glucocorticoid-induced insulin resistance in skeletal muscle
OBJECTIVE: Glucocorticoid excess is characterized by increased adiposity, skeletal myopathy, and insulin resistance, but the precise molecular mechanisms are unknown. Within skeletal muscle, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts cortisone (11-dehydrocorticosterone in rodents) to active cortisol (corticosterone in rodents). We aimed to determine the mechanisms underpinning glucocorticoid-induced insulin resistance in skeletal muscle and indentify how 11beta-HSD1 inhibitors improve insulin sensitivity. \ud
RESEARCH DESIGN AND METHODS: Rodent and human cell cultures, whole-tissue explants, and animal models were used to determine the impact of glucocorticoids and selective 11beta-HSD1 inhibition upon insulin signaling and action. \ud
RESULTS: Dexamethasone decreased insulin-stimulated glucose uptake, decreased IRS1 mRNA and protein expression, and increased inactivating pSer insulin receptor substrate (IRS)-1. 11beta-HSD1 activity and expression were observed in human and rodent myotubes and muscle explants. Activity was predominantly oxo-reductase, generating active glucocorticoid. A1 (selective 11beta-HSD1 inhibitor) abolished enzyme activity and blocked the increase in pSer IRS1 and reduction in total IRS1 protein after treatment with 11DHC but not corticosterone. In C57Bl6/J mice, the selective 11beta-HSD1 inhibitor, A2, decreased fasting blood glucose levels and improved insulin sensitivity. In KK mice treated with A2, skeletal muscle pSer IRS1 decreased and pThr Akt/PKB increased. In addition, A2 decreased both lipogenic and lipolytic gene expression.\ud
CONCLUSIONS: Prereceptor facilitation of glucocorticoid action via 11beta-HSD1 increases pSer IRS1 and may be crucial in mediating insulin resistance in skeletal muscle. Selective 11beta-HSD1 inhibition decreases pSer IRS1, increases pThr Akt/PKB, and decreases lipogenic and lipolytic gene expression that may represent an important mechanism underpinning their insulin-sensitizing action
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