2,145 research outputs found

    Oceanographic Data Collected in the Chesapeake Bight of the Virginian Sea from 1966 though 1969

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    This report is intended to make unsynthesized oceanographic data readily available to the scientific community. 3 Similar reports are envisioned which will include physical, chemical, biological and geological data collected by personnel of the Virginia Institute ·of Marine Science in areas of the continental shelf, and coastal zone to include beaches, wetlands, estuaries and tidal rivers - areas in which the Commonwealth of Virginia has a vested interest

    Strain-driven elastic and orbital-ordering effects on thickness-dependent properties of manganite thin films

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    We report on the structural and magnetic characterization of (110) and (001) La2/3Ca1/3MnO3 (LCMO) epitaxial thin films simultaneously grown on (110) and (001)SrTiO3 substrates, with thicknesses t varying between 8 nm and 150 nm. It is found that while the in-plane interplanar distances of the (001) films are strongly clamped to those of the substrate and the films remain strained up to well above t=100 nm, the (110) films relax much earlier. Accurate determination of the in-plane and out-of-plane interplanar distances has allowed concluding that in all cases the unit cell volume of the manganite reduces gradually when increasing thickness, approaching the bulk value. It is observed that the magnetic properties (Curie temperature and saturation magnetization) of the (110) films are significantly improved compared to those of (001) films. These observations, combined with 55Mn-nuclear magnetic resonance data and X-ray photoemission spectroscopy, signal that the depression of the magnetic properties of the more strained (001)LCMO films is not caused by an elastic deformation of the perovskite lattice but rather due to the electronic and chemical phase separation caused by the substrate-induced strain. On the contrary, the thickness dependence of the magnetic properties of the less strained (110)LCMO films are simply described by the elastic deformation of the manganite lattice. We will argue that the different behavior of (001) and (110)LCMO films is a consequence of the dissimilar electronic structure of these interfaces.Comment: 16 pages, 15 figure

    Effect of growth pressure on coalescence thickness and crystal quality of GaN deposited on 4H-SiC

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    Cataloged from PDF version of article.The influence of growth pressure on the coalescence thickness and the crystal quality of GaN deposited on 4H-SiC by low pressure metalorganic vapor phase epitaxy was studied. It was shown that growth pressure has an impact on the surface roughness of epilayers and their crystal quality. GaN coalescence thicknesses were determined for the investigated growth pressures. The GaN layers were characterized by AFM and HRXRD measurements. HEMT structures were also fabricated and characterized. Among the growth pressures studied, 50, 125 and 200 mbar, 200 mbar was found to be most suitable for GaN/SiC epitaxy. (C) 2010 Elsevier B.V. All rights reserved

    Plasma Proteomic Profiles of Cerebrospinal Fluid-Defined Alzheimer's Disease Pathology in Older Adults.

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    Cerebrospinal fluid (CSF) biomarkers of the beta-amyloid and microtubule associated protein tau metabolism have proven the capacity to improve classification of subjects developing Alzheimer's disease (AD). The blood plasma proteome was characterized to further elaborate upon the mechanisms involved and identify proteins that may improve classification of older adults developing an AD dementia. Identify and describe plasma protein expressions that best classify subjects with CSF-defined presence of AD pathology and cerebral amyloidosis. We performed a cross-sectional analysis of samples collected from community-dwelling elderly with (n = 72) or without (n = 48) cognitive impairment. CSF Aβ1-42, tau, and phosphorylated tau (P-tau181) were measured using ELISA, and mass spectrometry quantified the plasma proteomes. Presence of AD pathology was defined as CSF P-tau181/Aβ1-42 > 0.0779, and presence of amyloidosis was defined as CSF Aβ1-42 < 724 pg/mL. Two hundred and forty-eight plasma proteins were quantified. Plasma proteins did not improve classification of the AD CSF biomarker profile in the whole sample. When the analysis was separately performed in the cognitively impaired individuals, the diagnosis accuracy of AD CSF profile was 88.9% with 19 plasma proteins included. Within the full cohort, there were 16 plasma proteins that improved diagnostic accuracy of cerebral amyloidosis to 92.4%. Plasma proteins improved classification accuracy of AD pathology in cognitively-impaired older adults and appeared representative of amyloid pathology. If confirmed, those candidates could serve as valuable blood biomarkers of the preclinical stages of AD or risk of developing AD

    Electronic self-doping of Mo-states in A2FeMoO6 (A=Ca, Sr and Ba) half-metallic ferromagnets - a Nuclear Magnetic Resonance study

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    A systematic study of (A,A')2FeMoO6 (A,A'=Ca, Sr, Ba) ferromagnetic oxides with double perovskite structure has been performed using 95,97Mo and 57Fe NMR spectroscopy. These oxides are isoelectronic but have substantially different Curie temperatures. The NMR analysis provides clear evidence that the magnetic moment at Mo sites is not constant but varies sensitively with the ionic size of the alkaline ions. The 95,97Mo frequency, and thus the electronic charge at Mo ions, is found to be smaller in Ba and Ca than in Sr-based oxides. The charge release from Mo sites is accompanied by an uptake at Fe sites, and thus a self-doping Fe-Mo process is observed. This process is controlled by relevant structural parameters: the Fe-O-Mo bond length and bending. A clear relationship between the Curie temperature and the magnetic moment and thus electron density at Mo sites has been disclosed. The relevance of these findings for the understanding of ferromagnetic coupling in double perovskites is discussed.Comment: 26 pages, 8 figure

    Ammonia Measurements and Emissions from a California Dairy Using Point and Remote Sensors

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    Ammonia (NH3) is an important trace gas species in the atmosphere that can have negative impacts on human, animal, and ecosystem health. Agriculture has been identified as the largest source of NH3, specifically livestock operations. NH3 emissions from a commercial dairy in California were investigated during June 2008. Cattle were held in open-lot pens, except for young calves in hutches with shelters. Solid manure was stored in the open-lot pens. Liquid manure from feed lanes was passed through a solids settling basin and stored in a holding pond. Passive sensors and openpath Fourier transform infrared spectrometers (OP-FTIR) were deployed around the facility to measure NH3 concentrations. Emissions from pens and the liquid manure system (LMS) were estimated using inverse modeling. Mean emission factors (EFs) for the entire facility were 140.5 ±42.5 g d-1 animal-1 from the passive sampler data and 199.2 ±22.0 g d-1 animal-1 from the OP-FTIR data, resulting in the facility’s summer emissions calculated at 265.2 ±80.2 kg d-1 and 375.4 ±27.1 kg d-1, respectively. These EFs are within the range of values reported in the literature. Both concentrations and emissions exhibited a strong diurnal cycle, peaking in the late afternoon. Total facility emissions exhibited significant positive correlations with temperature and wind speed. The findings of this study show that NH3 emissions from a commercial dairy can vary by a factor of 10 or more throughout the day, and EFs can vary by two orders of magnitude when compared to other U.S. dairies, based on literature values

    Markers of neuroinflammation associated with Alzheimer's disease pathology in older adults.

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    In vitro and animal studies have linked neuroinflammation to Alzheimer's disease (AD) pathology. Studies on markers of inflammation in subjects with mild cognitive impairment or AD dementia provided inconsistent results. We hypothesized that distinct blood and cerebrospinal fluid (CSF) inflammatory markers are associated with biomarkers of amyloid and tau pathology in older adults without cognitive impairment or with beginning cognitive decline. To identify blood-based and CSF neuroinflammation marker signatures associated with AD pathology (i.e. an AD CSF biomarker profile) and to investigate associations of inflammation markers with CSF biomarkers of amyloid, tau pathology, and neuronal injury. Cross-sectional analysis was performed on data from 120 older community-dwelling adults with normal cognition (n=48) or with cognitive impairment (n=72). CSF Aβ1-42, tau and p-tau181, and a panel of 37 neuroinflammatory markers in both CSF and serum were quantified. Least absolute shrinkage and selection operator (LASSO) regression was applied to determine a reference model that best predicts an AD CSF biomarker profile defined a priori as p-tau181/Aβ1-42 ratio >0.0779. It was then compared to a second model that included the inflammatory markers from either serum or CSF. In addition, the correlations between inflammatory markers and CSF Aβ1-42, tau and p-tau181 levels were assessed. Forty-two subjects met criteria for having an AD CSF biomarker profile. The best predictive models included 8 serum or 3 CSF neuroinflammatory markers related to cytokine mediated inflammation, vascular injury, and angiogenesis. Both models improved the accuracy to predict an AD biomarker profile when compared to the reference model. In analyses separately performed in the subgroup of participants with cognitive impairment, adding the serum or the CSF neuroinflammation markers also improved the accuracy of the diagnosis of AD pathology. None of the inflammatory markers correlated with the CSF Aβ1-42 levels. Six CSF markers (IL-15, MCP-1, VEGFR-1, sICAM1, sVCAM-1, and VEGF-D) correlated with the CSF tau and p-tau181 levels, and these associations remained significant after controlling for age, sex, cognitive impairment, and APOEε4 status. The identified serum and CSF neuroinflammation biomarker signatures improve the accuracy of classification for AD pathology in older adults. Our results suggest that inflammation, vascular injury, and angiogenesis as reflected by CSF markers are closely related to cerebral tau pathology

    'Surely the most natural scenario in the world’: Representations of ‘Family’ in BBC Pre-school Television

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    Historically, the majority of work on British children’s television has adopted either an institutional or an audience focus, with the texts themselves often overlooked. This neglect has meant that questions of representation in British children’s television – including issues such as family, gender, class or ethnicity - have been infrequently analysed in the UK context. In this article, we adopt a primarily qualitative methodology and analyse the various textual manifestations of ‘family’, group, or community as represented in a selected number of BBC pre-school programmes. In doing so, we question the (limited amount of) international work that has examined representations of the family in children’s television, and argue that nuclear family structures do not predominate in this sphere
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