155 research outputs found

    Analysis and methodology for aeronautical systems technology program planning

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    A structured methodology was developed that allows the generation, analysis, and rank-ordering of system concepts by their benefits and costs, indicating the preferred order of implementation. The methodology is supported by a base of data on civil transport aircraft fleet growth projections and data on aircraft performance relating the contribution of each element of the aircraft to overall performance. The performance data are used to assess the benefits of proposed concepts. The methodology includes a computer program for performing the calculations needed to rank-order the concepts and compute their cumulative benefit-to-cost ratio. The use of the methodology and supporting data is illustrated through the analysis of actual system concepts from various sources

    Innate immunity glycoprotein gp-340 variants may modulate human susceptibility to dental caries

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    <p>Abstract</p> <p>Background</p> <p>Bacterial adhesion is an important determinant of colonization and infection, including dental caries. The salivary scavenger receptor cysteine-rich glycoprotein gp-340, which mediates adhesion of <it>Streptococcus mutans </it>(implicated in caries), harbours three major size variants, designated gp-340 I to III, each specific to an individual saliva. Here we have examined the association of the gp-340 I to III polymorphisms with caries experience and adhesion of <it>S. mutans</it>.</p> <p>Methods</p> <p>A case-referent study was performed in 12-year-old Swedish children with high (n = 19) or low (n = 19) caries experiences. We measured the gp-340 I to III saliva phenotypes and correlated those with multiple outcome measures for caries experience and saliva adhesion of <it>S. mutans </it>using the partial least squares (PLS) multivariate projection technique. In addition, we used traditional statistics and 2-year caries increment to verify the established PLS associations, and bacterial adhesion to purified gp-340 I to III proteins to support possible mechanisms.</p> <p>Results</p> <p>All except one subject were typed as gp-340 I to III (10, 23 and 4, respectively). The gp-340 I phenotype correlated positively with caries experience (VIP = 1.37) and saliva adhesion of <it>S. mutans </it>Ingbritt (VIP = 1.47). The gp-340 II and III phenotypes tended to behave in the opposite way. Moreover, the gp-340 I phenotype tended to show an increased 2-year caries increment compared to phenotypes II/III. Purified gp-340 I protein mediated markedly higher adhesion of <it>S. mutans </it>strains Ingbritt and NG8 and <it>Lactococcus lactis </it>expressing AgI/II adhesins (SpaP or PAc) compared to gp-340 II and III proteins. In addition, the gp-340 I protein appeared over represented in subjects positive for Db, an allelic acidic PRP variant associated with caries, and subjects positive for both gp-340 I and Db tended to experience more caries than those negative for both proteins.</p> <p>Conclusion</p> <p>Gp-340 I behaves as a caries susceptibility protein.</p

    Фоточувствительные структуры с каскадными концентраторами излучения на основе коллоидных квантовых точек халькогенидов металлов

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    Introduction. The problem of increasing the efficiency of existing photodetectors and creating their new types attracts much research attention. Among new photodetector types are photosensitive structures based on cascade concentrators, whose operational principle involves the absorption of optical radiation followed by its reemission at a longer wavelength and radiation concentration onto a highly efficient small-area photodetector. The absorption and re-emission spectra of each cascade layer depend on the characteristics of the material used. Сolloidal quantum dots are among the most promising materials for cascade layers due to their manufacturing technology, which provides for accurate control over the photoluminescence maximum position. It seems highly relevant to develop and to study photosensitive structures with cascade concentrators of various shapes based on CdS, CdSe/ZnS, and PbS colloidal quantum dots.Aim. To develop photosensitive structures with a wide-range sensitivity spectrum based on concentrators containing arrays of metal chalcogenide CQDs and to study their characteristics.Materials and methods. Cascade photosensitive structures were manufactured based on layers made of polymethyl methacrylate and layers of colloidal quantum dots embedded in a polystyrene matrix.Results. Three-layer concentrators were manufactured with different colloidal quantum dots in each concentrator layers. A 22 % increase in the output power was observed for a three-layer cascade structure based on different cascade layer materials compared to a similar structure using a single layer concentrator.Conclusion. The conducted studies showed an increase in the efficiency of photosensitive structures with a cascade concentrator based on colloidal quantum dots of various types (CdS, CdSe/ZnS, and PbS) in the cascade layers.Введение. В настоящее время актуально повышение эффективности существующих и создание новых типов фотоприемников. К таким фотоприемникам относятся фоточувствительные структуры на основе каскадных концентраторов, принцип действия которых основан на поглощении оптического излучения с последующим переизлучением на большей длине волны и концентрировании излучения на высокоэффективный фотоприемник малой площади. Спектры поглощения и переизлучения каждого слоя каскада зависят от характеристик используемого материала. Одним из наиболее перспективных материалов для слоев каскада являются коллоидные квантовые точки (ККТ), технология производства которых позволяет точно управлять положением максимума фотолюминесценции. Актуальным является создание и исследование фоточувствительных структур с каскадными концентраторами различной формы на основе ККТ CdS, CdSe/ZnS и PbS.Цель работы. Создание и исследование фоточувствительных структур со спектром чувствительности в широком диапазоне на основе концентраторов, содержащих массивы ККТ халькогенидов металлов, и исследование их характеристик.Материалы и методы. Каскадные фоточувствительные структуры изготовлены на основе слоев, выполненных из полиметилметакрилата и слоев ККТ, заключенных в матрицу из полистирола.Результаты. Приведены результаты исследования изготовленных трехслойных концентраторов с различными коллоидными квантовыми точками в каждом из слоев концентратора. Показано увеличение выходной мощности на 22 % для структуры трехслойного каскада, в котором использовались различные материалы слоев, по сравнению с аналогичной структурой, использующей однослойный концентратор.Заключение. Исследования показали повышение эффективности фоточувствительных структур с каскадным концентратором на основе ККТ различного типа (CdS, CdSe/ZnS и PbS) в слоях каскада

    Metal Ion-dependent Heavy Chain Transfer Activity of TSG-6 Mediates Assembly of the Cumulus-Oocyte Matrix

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    The matrix polysaccharide hyaluronan (HA) has a critical role in the expansion of the cumulus cell-oocyte complex (COC), a process that is necessary for ovulation and fertilization in most mammals. Hyaluronan is organized into a cross-linked network by the cooperative action of three proteins, inter-α-inhibitor (IαI), pentraxin-3, and TNF-stimulated gene-6 (TSG-6), driving the expansion of the COC and providing the cumulus matrix with its required viscoelastic properties. Although it is known that matrix stabilization involves the TSG-6-mediated transfer of IαI heavy chains (HCs) onto hyaluronan (to form covalent HC·HA complexes that are cross-linked by pentraxin-3) and that this occurs via the formation of covalent HC·TSG-6 intermediates, the underlying molecular mechanisms are not well understood. Here, we have determined the tertiary structure of the CUB module from human TSG-6, identifying a calcium ion-binding site and chelating glutamic acid residue that mediate the formation of HC·TSG-6. This occurs via an initial metal ion-dependent, non-covalent, interaction between TSG-6 and HCs that also requires the presence of an HC-associated magnesium ion. In addition, we have found that the well characterized hyaluronan-binding site in the TSG-6 Link module is not used for recognition during transfer of HCs onto HA. Analysis of TSG-6 mutants (with impaired transferase and/or hyaluronan-binding functions) revealed that although the TSG-6-mediated formation of HC·HA complexes is essential for the expansion of mouse COCs in vitro, the hyaluronan-binding function of TSG-6 does not play a major role in the stabilization of the murine cumulus matrix

    Reporting Recommendations for Tumor Marker Prognostic Studies (REMARK): Explanation and Elaboration

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    The REMARK “elaboration and explanation” guideline, by Doug Altman and colleagues, provides a detailed reference for authors on important issues to consider when designing, conducting, and analyzing tumor marker prognostic studies

    Trophic Ecology of Atlantic Bluefin Tuna (Thunnus thynnus) Larvae from the Gulf of Mexico and NW Mediterranean Spawning Grounds: A Comparative Stable Isotope Study

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    The present study uses stable isotopes of nitrogen and carbon (δ15Nandδ13C) as trophic indicators for Atlantic bluefin tuna larvae (BFT) (6–10mm standard length) in the highly contrasting environmental conditions of the Gulf of Mexico (GOM) and the Balearic Sea (MED). These regions are differentiated by their temperature regime and relative productivity, with the GOM being significantly warmer and more productive. MED BFT larvae showed the highest δ15N signatures, implying an elevated trophic position above the underlyingmicrozooplankton baseline. Ontogenetic dietary shifts were observed in the BFT larvae from the GOM and MED which indicates early life trophodynamics differences between these spawning habitats. Significant trophic differences between the GOM and MED larvae were observed in relation to δ15N signatures in favour of the MED larvae, which may have important implications in their growth during their early life stages. These low δ15N levels in the zooplankton from the GOM may be an indication of a shifting isotopic baseline in pelagic food webs due to diatrophic inputs by cyanobacteria. Lack of enrichment for δ15N in BFT larvae compared to zooplankton implies an alternative grazing pathway from the traditional food chain of phytoplankton— zooplankton—larval fish. Results provide insight for a comparative characterization of the trophic pathways variability of the two main spawning grounds for BFT larvaeVersión del editor4,411

    Electron-microscopic demonstration of proline-rich proteins, statherin, and histatins in acquired enamel pellicles in vitro.

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    Proline-rich proteins (PRPs), histatins, and statherin are salivary proteins that exhibit high affinities for hydroxyapatite surfaces. In vitro experiments with parotid submandibular/sublingual or whole saliva have shown these proteins to adsorb selectively to tooth surfaces. This investigation focuses on the histo-morphological identification of PRPs, histatins, and statherin in acquired enamel pellicles. Synthetic hydroxyapatite or bovine enamel were exposed to glandular secretions, and whole saliva and pellicle precursor proteins were identified immunohistologically by electron microscopy. Results obtained by back-scattered scanning electron microscopy showed these proteins to be present in pellicles. Pellicles displayed a distinct structure consisting of a sponge-like meshwork of microglobules. Interconnections between structural elements were identified in submandibular/sublingual and whole saliva pellicles only. Transmission electron microscopy of pellicles formed on bovine enamel surfaces revealed a tendency for preferential localization of precursor proteins within the protein film. Since the data showed the presence of pellicle precursors in pellicles derived both from glandular secretions and from whole saliva, it is likely that PRPs, histatins, and statherin are integral components of acquired enamel pellicles in vivo

    A Comparison of Sampling Methods for Larvae of Medium and Large Epipelagic Fish Species during Spring Seamap Ichthyoplankton Surveys in the Gulf of Mexico

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    Annual ichthyoplankton surveys have been conducted in the Gulf of Mexico during spring since 1982 by the National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service (NMFS) Southeast Area Monitoring and Assessment Program (SEAMAP). Historically, ichthyoplankton has been assessed using bongo and surface neuston nets. A new sampling gear, the S-10 net, was tested between 2009 and 2011. This is a 1 × 2 m frame fitted with a 0.505 mm mesh net, towed in a yo-yo fashion between the surface and 10 m. Sampling effectiveness of the three gears was compared by examining the abundance and length of larvae of bluefin tuna (Thunnus thynnus) and seven co-occurring pelagic taxa (Auxis spp., Euthynnus alleteratus, Coryphaena spp., Katsuwonus pelamis, other Thunnus spp., family Istiophoridae, and Xiphias gladius) and vertical distributions of scombrid taxa were examined using MOCNESS samples. Permutational multivariate analysis of variance (PERMANOVA) of net type and time of sampling (day/night) indicated that net type was a significant factor in assessing abundance and length for all taxa. Highest abundances for seven of eight taxa were in S-10 samples, and MOCNESS samples confirm highest scombrid abundance between the surface and 20 m. Our results show sampling effectiveness strongly depends on the depth fished by the net and that the S-10 net was more effective than standard SEAMAP bongo and neuston nets. Thus, future sampling with the S-10 net may improve the annual index of larval abundance for the western population of Atlantic bluefin tuna, traditionally based on abundance from bongo samples
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