1,578 research outputs found

    Physical optics for oven-plate scattering prediction

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    An oven assembly design is described, which will be used to determine the effects of temperature on the electrical properties of materials which are used as coatings for metal plates. Experimentally, these plates will be heated to a very high temperature in the oven assembly, and measured using a microwave reflectance measurement system developed for the NASA Lewis Research Center, Near-Field Facility. One unknown in this measurement is the effect that the oven assembly will have on the reflectance properties of the plate. Since the oven will be much larger than the plate, the effect could potentially be significant as the size of the plate becomes smaller. Therefore, it is necessary to predict the effect of the oven on the measurement of the plate. A method for predicting the oven effect is described, and the theoretical oven effect is compared to experimental results of the oven material. The computer code which is used to predict the oven effect is also described

    A plant-made cholera toxin B subunit enhances mucosal wound healing and protects against ulcerative colitis and colon cancer.

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    This dissertation describes the previously unidentified effects of a plant-produced recombinant cholera toxin B subunit (CTBp) on the gastrointestinal (GI) tract and its ability to protect against inflammation in a mouse model of colonic injury and ulcerative colitis (UC). To comprehensively analyze CTBp’s impacts on the GI tract, we employed global analysis methodologies based on multi-color flow cytometry to analyze immune cell populations in GI and systemic lymphatic compartments, gene expression microarray to decipher transcript-level changes in the colon and small intestine, and 16S rRNA sequencing to characterize fecal microbiota. Based on a drastic shift observed in the immune cell profile and gene expression pattern in the distal colon, we built a new working hypothesis that CTBp may enhance mucosal protection in the colon. To address this hypothesis, we used the Caco-2 human colonic cell line and the mouse dextran sulfate sodium (DSS) colitis model. After demonstrating the potential of CTBp as a mucosal healing and anti-colitic agent, the dissertation will be summarized and future directions discussed

    Acetaldehyde dehydrogenase 2 (ALDH2) activation protects hepatocytes from mitochondrial damage and death caused by 4-hydroxynonenal.

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    Alcoholic liver disease (ALD) ranks among the major causes of morbidity and mortality in the world and effects millions of patients each year. Progression of ALD is well characterized and is actually a spectrum of liver diseases, which progresses from steatosis, to inflammation and necrosis, to finally fibrosis and cirrhosis. However, the underlying mechanism(s) of ALD are not as well understood, and as a result there is no FDA-approved therapy to prevent or reverse the disease. With a better understanding of the mechanism(s) and risk factors that mediate the initiation and progression of ALD, a targeted therapy can be developed to treat or prevent it. The regenerative capacity of the liver is inhibited in fibrosis and cirrhosis. By enhancing the regenerative ability of the liver we may be able to reverse the effects of ALD. Indeed, recent in vivo studies by this group indicate that activating Aldehyde Dehydrogenase 2 (ALDH2) with Alda-1 (a novel ALDH2 activator) or Ethanol (EtOH) protects against oxidative stress and damage to the liver, as result enhancing regeneration. Because ALDH2 can protect mitochondria from oxidative stress that results from partial hepatectomy, oxidative stress from other sources should be protected against as well. To test this hypothesis, primary hepatocytes were isolated from mice and plated on 96-well plates for analysis via Cellomics High Content Screening. Some mice were administered EtOH for 3 days prior to hepatocyte isolation or exposed to Alda-1 to activate ALDH2. Cells were exposed to 4-Hydroxynonenal (4-HNE; 0-1000 µM) for 0-24 H. Activation of ALDH2, by pretreatment with EtOH or Alda-1 preexposure, clearly protected isolated hepatocytes from 4-HNE toxicity. Mitochondrial membrane potential was significantly increased in cells with activated ALDH2 and membrane permeability was decreased in these cells as well. These changes in hepatocyte viability indicate that activation of ALDH2 protects cells from oxidative stress

    Evidence for Quadratic Tidal Tensor Bias from the Halo Bispectrum

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    The relation between the clustering properties of luminous matter in the form of galaxies and the underlying dark matter distribution is of fundamental importance for the interpretation of ongoing and upcoming galaxy surveys. The so called local bias model, where galaxy density is a function of local matter density, is frequently discussed as a means to infer the matter power spectrum or correlation function from the measured galaxy correlation. However, gravitational evolution generates a term quadratic in the tidal tensor and thus non-local in the density field, even if this term is absent in the initial conditions (Lagrangian space). Because the term is quadratic, it contributes as a loop correction to the power spectrum, so the standard linear bias picture still applies on large scales, however, it contributes at leading order to the bispectrum for which it is significant on all scales. Such a term could also be present in Lagrangian space if halo formation were influenced by the tidal field. We measure the corresponding coupling strengths from the matter-matter-halo bispectrum in numerical simulations and find a non-vanishing coefficient for the tidal tensor term. We find no scale dependence of the bias parameters up to k=0.1 h/Mpc and that the tidal effect is increasing with halo mass. While the Lagrangian bias picture is a better description of our results than the Eulerian bias picture, our results suggest that there might be a tidal tensor bias already in the initial conditions. We also find that the coefficients of the quadratic density term deviate quite strongly from the theoretical predictions based on the spherical collapse model and a universal mass function. Both quadratic density and tidal tensor bias terms must be included in the modeling of galaxy clustering of current and future surveys if one wants to achieve the high precision cosmology promise of these datasets.Comment: 14 pages, 4 figures, 1 tabl

    The origins of species richness in the Hymenoptera: insights from a family-level supertree

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    <p>Abstract</p> <p>Background</p> <p>The order Hymenoptera (bees, ants, wasps, sawflies) contains about eight percent of all described species, but no analytical studies have addressed the origins of this richness at family-level or above. To investigate which major subtaxa experienced significant shifts in diversification, we assembled a family-level phylogeny of the Hymenoptera using supertree methods. We used sister-group species-richness comparisons to infer the phylogenetic position of shifts in diversification.</p> <p>Results</p> <p>The supertrees most supported by the underlying input trees are produced using matrix representation with compatibility (MRC) (from an all-in and a compartmentalised analysis). Whilst relationships at the tips of the tree tend to be well supported, those along the backbone of the tree (e.g. between Parasitica superfamilies) are generally not. Ten significant shifts in diversification (six positive and four negative) are found common to both MRC supertrees. The Apocrita (wasps, ants, bees) experienced a positive shift at their origin accounting for approximately 4,000 species. Within Apocrita other positive shifts include the Vespoidea (vespoid wasps/ants containing 24,000 spp.), Anthophila + Sphecidae (bees/thread-waisted wasps; 22,000 spp.), Bethylidae + Chrysididae (bethylid/cuckoo wasps; 5,200 spp.), Dryinidae (dryinid wasps; 1,100 spp.), and Proctotrupidae (proctotrupid wasps; 310 spp.). Four relatively species-poor families (Stenotritidae, Anaxyelidae, Blasticotomidae, Xyelidae) have undergone negative shifts. There are some two-way shifts in diversification where sister taxa have undergone shifts in opposite directions.</p> <p>Conclusions</p> <p>Our results suggest that numerous phylogenetically distinctive radiations contribute to the richness of large clades. They also suggest that evolutionary events restricting the subsequent richness of large clades are common. Problematic phylogenetic issues in the Hymenoptera are identified, relating especially to superfamily validity (e.g. "Proctotrupoidea", "Mymarommatoidea"), and deeper apocritan relationships. Our results should stimulate new functional studies on the causes of the diversification shifts we have identified. Possible drivers highlighted for specific adaptive radiations include key anatomical innovations, the exploitation of rich host groups, and associations with angiosperms. Low richness may have evolved as a result of geographical isolation, specialised ecological niches, and habitat loss or competition.</p

    A Study of Selected Chemical and Biological Conditions of the Lower Trinity River and the Upper Trinity Bay

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    Concern over the effects of water development projects on coastal nurseries prompted the Department of Wildlife Science of Texas A&M University, with the cooperation of the UO So Bureau of Commercial Fisheries, Galveston, to undertake a study of a threatened nursery in the Galveston Bay System. A long-range program for the development of the Trinity River Drainage Basin includes the construction of several multi-purpose reservoirs along the main river (Fickessen, 1965). Of immediate threat to Galveston Bay nurseries was the reservoir to be constructed at Wallisville, Texas (Trinity River Mile 3.9)0 The site is close to Trinity Bay and the dam will traverse the relatively wide deltaic region of the Trinity River (Figure 2). The completed dam will serve as an effective barrier to salt water. Approximately 12,500 acres of marsh behind the dam will be come a freshwater conservation pool. The marsh area below the dam (8,200 acres) will also be modified through changes in the freshwater flow. It is assumed that tile Wallisville Dam will be completed and that many of the conditions described here for the study area will be drastically changed. The aim of this study was to gather data which would establish file role of the threatened marsh as a nursery for important marine and estuarine species It is recognized that these data will serve in planning and evaluating future water projects of this nature. Data reported here cover the period from March, 1966, through May, 1968. The study was limited to commercially important species with special emphasis given to the shrimps. The Bureau of Commercial Fisheries had maintained collecting stations in trinity Bay and made several preliminary investigations in the area of the proposed Wallisville Reservoir, but the actual extent to which commercially important species were utilizing these threatened wetlands was unknown. This paper attempts to demonstrate the extent to which the marsh has been utilized by the white shrimp (Penaeus setiferus Linnaeus), the brown shrimp (Penaeus aztecus Ives), the blue crab (Callinectes sapidus Rathburl), and the Gulf menhaden (Brevoortia patronus Goode). Some of the information presented here may be pertinent to an understanding of the same species in other low salinity environments

    A network model of language policy and planning: The United Nations as a case study

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    This paper contributes to recent critical discussion of ‘agency’ in LPP research and practice. It argues that whilst scholars have widened their purview to consider the impact of individual actors on LPP in different contexts, the field has not developed or embraced theoretical and methodological frameworks which satisfactorily model or investigate the network of actor impact on LPP. This article analyses the current status of LPP at the United Nations (UN). Taking the ‘Actor-Stage Model’ (Zhao & Baldauf, 2012) as a theoretical point of departure, the paper discusses and analyses the most recent review of LPP within the UN. It becomes apparent that a network of agents is responsible for LPP development, influence and implementation within the organisation. This ‘web of influence’ is schematised using a network model which accounts for the implicit and explicit responsibility of multiple actors/’experts’ within and outside of the organisation. A sub-analysis of institutional LPP goals reveals the ‘polycentric’ and ‘relational’ nature of influence within and across multiple ’nodes’. It is argued that the network model and the concept of ‘web of influence’ is crucial in de- and re-constructing particular LPP goals and serves as a useful heuristic for those investigating or working within similar sites of inter/transnational integration as well as LPP in other macro, meso or micro-contexts

    The SQM/COSMO filter: reliable native pose identification based on the quantum-mechanical description of protein–ligand interactions and implicit COSMO solvation

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    Current virtual screening tools are fast, but reliable scoring is elusive. Here, we present the "SQM/COSMO filter", a novel scoring function featuring a quantitative semiempirical quantum mechanical (SQM) description of all types of noncovalent interactions coupled with implicit COSMO solvation. We show unequivocally that it outperforms eight widely used scoring functions. The accuracy and chemical generality of the SQM/COSMO filter make it a perfect tool for late stages of virtual screening

    An algorithm for the direct reconstruction of the dark matter correlation function from weak lensing and galaxy clustering

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    The clustering of matter on cosmological scales is an essential probe for studying the physical origin and composition of our Universe. To date, most of the direct studies have focused on shear-shear weak lensing correlations, but it is also possible to extract the dark matter clustering by combining galaxy-clustering and galaxy-galaxy-lensing measurements. In this study we develop a method that can constrain the dark matter correlation function from galaxy clustering and galaxy-galaxy-lensing measurements, by focusing on the correlation coefficient between the galaxy and matter overdensity fields. To generate a mock galaxy catalogue for testing purposes, we use the Halo Occupation Distribution approach applied to a large ensemble of N-body simulations to model pre-existing SDSS Luminous Red Galaxy sample observations. Using this mock catalogue, we show that a direct comparison between the excess surface mass density measured by lensing and its corresponding galaxy clustering quantity is not optimal. We develop a new statistic that suppresses the small-scale contributions to these observations and show that this new statistic leads to a cross-correlation coefficient that is within a few percent of unity down to 5 Mpc/h. Furthermore, the residual incoherence between the galaxy and matter fields can be explained using a theoretical model for scale-dependent bias, giving us a final estimator that is unbiased to within 1%. We also perform a comprehensive study of other physical effects that can affect the analysis, such as redshift space distortions and differences in radial windows between galaxy clustering and weak lensing observations. We apply the method to a range of cosmological models and show the viability of our new statistic to distinguish between cosmological models.Comment: 23 pages, 14 figures, accepted by PRD; minor changes to V1, 1 new figure, more detailed discussion of the covariance of the new ADSD statisti

    Context-aware and automatic configuration of mobile devices in cloud-enabled ubiquitous computing

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    This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s00779-013-0698-3. Copyright @ Springer-Verlag London 2013.Context-sensitive (or aware) applications have, in recent years, moved from the realm of possibilities to that of ubiquity. One exciting research area that is still very much in the realm of possibilities is that of cloud computing, and in this paper, we present our work, which explores the overlap of these two research areas. Accordingly, this paper explores the notion of cross-source integration of cloud-based, context-aware information in ubiquitous computing through a developed prototypical solution. Moreover, the described solution incorporates remote and automatic configuration of Android smartphones and advances the research area of context-aware information by harvesting information from several sources to build a rich foundation on which algorithms for context-aware computation can be based. Evaluation results show the viability of integrating and tailoring contextual information to provide users with timely, relevant and adapted application behaviour and content
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