930 research outputs found

    Aluminum-titanium hydride-boron carbide composite provides lightweight neutron shield material

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    Inexpensive lightweight neutron shield material has high strength and ductility and withstands high internal heat generation rates without excessive thermal stress. This composite material combines structural and thermal properties of aluminum, neutron moderating properties of titanium hydride, and neutron absorbing characteristics of boron carbide

    Legislation and Education as Strategies to Reduce Behavioral Health Risk Factors in the State of Nebraska

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    In the interest of improving health care planning and practice, this paper exami~es legislation and educational strategies designed to reduce behavioral health risk factors in the state of Nebraska and the United States. The growing problem of modifying health behavior in the nation and Nebraska is reviewed, including trends in seat belt use, drinking and driving, smoking, hypertension, obesity, and sedentary lifestyle. Nebraska\u27s rate of death associated with these risk factors is higher than the national average. Several of the strategies which Nebraska and the United States have implemented are reviewed. Legislation to reduce the prevalence of seat belt nonuse, drinking and driving, and smoking, is one prevention strategy which has been developed and implemented in both Nebraska and the United States, although levels of enforcement and type of penalties vary. Despite legislative action, many people still find ways to violate the laws without punishment; therefore, education plays a critical role in prevention. If programs are targeted to the right demographic groups with the right methodology, legislation may become less important in controlling or modifying human behavior. The most recent national goals and objectives (Healthy People, 1991) developed by the federal government indicated that, although the rate of increase in the number of deaths which can be attributed to poor health behavior is rising more slowly than in previous years, there is still an increase, which ideally should be reversed by the year 2000. Over the last few decades, both legislative and educational strategies have produced some moderate changes in the overall health of our nation, but with more resources devoted to planning and implementing legislative and educational strategies, Nebraska and the nation overall demonstrate potential for successfully addressing the problems and achieving the goal of preventing deaths due to poor health behavior. Since the financial impact on our health care system and the economy is a very critical issue at the present time, improvements in health care planning and practice, as well as further research and evaluation are warranted. Adviser: Professor Gordon Schol

    Task 3.8 spent fuel storage and cooling requirements

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    Spitzer observations of a gravitationally lensed quasar, QSO 2237+0305

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    The four-image gravitationally lensed quasar QSO 2237+0305 is microlensed by stars in the lens galaxy. The amplitude of microlensing variability can be used to infer the relative size of the quasar as a function of wavelength; this provides a test of quasar models. Toward this end, we present Spitzer Space Telescope Infrared Spectrograph and Infrared Array Camera (IRAC) observations of QSO 2237+0305, finding the following. (1) The infrared (IR) spectral energy distribution (SED) is similar to that of other bright radio-quiet quasars, contrary to an earlier claim. (2) A dusty torus model with a small opening angle fits the overall shape of the IR SED well, but the quantitative agreement is poor due to an offset in wavelength of the silicate feature. (3) The flux ratios of the four lensed images can be derived from the IRAC data despite being unresolved. We find that the near-IR fluxes are increasingly affected by microlensing toward shorter wavelengths. (4) The wavelength dependence of the IRAC flux ratios is consistent with the standard quasar model in which an accretion disk and a dusty torus both contribute near 1 micron in the rest frame. This is also consistent with recent IR spectropolarimetry of nearby quasars

    Alternative mechanism for bacteriophage adsorption to the motile bacterium Caulobacter crescentus

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    2D and 3D cryo-electron microscopy, together with adsorption kinetics assays of Ï•Cb13 and Ï•CbK phage-infected Caulobacter crescentus, provides insight into the mechanisms of infection. Ï•Cb13 and Ï•CbK actively interact with the flagellum and subsequently attach to receptors on the cell pole. We present evidence that the first interaction of the phage with the bacterial flagellum takes place through a filament on the phage head. This contact with the flagellum facilitates concentration of phage particles around the receptor (i.e., the pilus portals) on the bacterial cell surface, thereby increasing the likelihood of infection. Phage head filaments have not been well characterized and their function is described here. Phage head filaments may systematically underlie the initial interactions of phages with their hosts in other systems and possibly represent a widespread mechanism of efficient phage propagation

    Electronic shielding by closed shells in salts of thulium

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    Electronic shielding by closed electron shells has been investigated in salts of trivalent thulium, by measuring the temperature dependence of the nuclear quadrupole splitting of the 8.42-keV gamma transition in Tm169. The measurements were performed by using the technique of recoilless nuclear resonance absorption. The nuclear quadrupole interaction was studied for Tm3+ ions in thulium ethyl sulfate, thulium oxide, and thulium trifluoride within a temperature range from 9.6 to 1970°K. The interpretation of the experimental data in terms of the contributions of distorted closed electron shells to the quadrupole interaction yields values for electronic shielding factors. The results lead to amounts of 10% or less for the atomic Sternheimer factor RQ. The experiments also reveal substantial shielding of the 4f electrons from the crystal electric field, expressed by the shielding factor σ2. Values of 250 and 130 are obtained for the ratio (1-γ∞)/(1-σ2) for thulium ethyl sulfate and thulium oxide, respectively, where γ∞ is the lattice Sternheimer factor

    Arecoline induced disruption of expression and localization of the tight junctional protein ZO-1 is dependent on the HER 2 expression in human endometrial Ishikawa cells

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    <p>Abstract</p> <p>Background</p> <p>Approximately 600 million people chew Betel nut, making this practice the fourth most popular oral habit in the world. Arecoline, the major alkaloid present in betel nut is one of the causative agents for precancerous lesions and several cancers of mouth among those who chew betel nut. Arecoline can be detected in the human embryonic tissue and is correlated to low birth weight of newborns whose mothers chew betel nut during pregnancy, suggesting that arecoline can induce many systemic effects. However, few reports exist as to the effects of arecoline in human tissues other than oral cancer cell lines. Furthermore, in any system, virtually nothing is known about the cellular effects of arecoline treatment on membrane associated signaling components of human cancer cells.</p> <p>Results</p> <p>Using the human Ishikawa endometrial cancer cell line, we investigated the effects of arecoline on expression, localization and functional connections between the ZO-1 tight junction protein and the HER2 EGF receptor family member. Treatment of Ishikawa cells with arecoline coordinately down-regulated expression of both ZO-1 and HER2 protein and transcripts in a dose dependent manner. Biochemical fractionation of cells as well as indirect immunofluorescence revealed that arecoline disrupted the localization of ZO-1 to the junctional complex at the cell periphery. Compared to control transfected cells, ectopic expression of exogenous HER2 prevented the arecoline mediated down-regulation of ZO-1 expression and restored the localization of ZO-1 to the cell periphery. Furthermore, treatment with dexamethasone, a synthetic glucocorticoid reported to up-regulate expression of HER2 in Ishikawa cells, precluded arecoline from down-regulating ZO-1 expression and disrupting ZO-1 localization.</p> <p>Conclusion</p> <p>Arecoline is known to induce precancerous lesions and cancer in the oral cavity of betel nut users. The arecoline down-regulation of ZO-1 expression and subcellular distribution suggests that arecoline potentially disrupts cell-cell interactions mediated by ZO-1, which may play a role in arecoline-mediated carcinogenesis. Furthermore, our study has uncovered the dependency of ZO-1 localization and expression on HER2 expression, which has therefore established a new cellular link between HER2 mediated signaling and apical junction formation involving ZO-1.</p

    Upregulation of Defensins in Burn Sheep Small Intestine

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    Objective: The aim of this study was to visualize and localize the sheep antimicrobials, β-defensins 1, 2, and 3, (SBD-1, SBD-2, SBD-3), sheep neutrophil defensin alpha (SNP-1), and the cathelicidin LL-37 in sheep small intestine after burn injury, our hypothesis being that these compounds would be upregulated in an effort to overcome a compromised endothelial lining. Response to burn injury includes the release of proinflammatory cytokines and systemic immune suppression that, if untreated, can progress to multiple organ failure and death, so protective mechanisms have to be initiated and implemented. Methods: Tissue sections were probed with antibodies to the antimicrobials and then visualized with fluorescently labeled secondary antibodies and subjected to fluorescence deconvolution microscopy and image reconstruction. Results: In both the sham and burn samples, all the aforementioned antimicrobials were seen in each of the layers of small intestine, the highest concentration being localized to the epithelium. SBD-2, SBD-3, and SNP-1 were upregulated in both enterocytes and Paneth cells, while SNP-1 and LL-37 showed increases in both the inner circular and outer longitudinal muscle layers of the muscularis externa following burn injury. Each of the defensins, except SBD-1, was also seen in between the muscle layers of the externa and while burn caused slight increases of SBD-2, SBD-3, and SNP-1 in this location, LL-37 content was significantly decreased. Conclusion: That while each of these human antimicrobials is present in multiple layers of sheep small intestine, SBD-2, SBD-3, SNP-1, and LL-37 are upregulated in the specific layers of the small intestine
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