396 research outputs found

    Optimal guidance law development for an advanced launch system

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    The proposed investigation on a Matched Asymptotic Expansion (MAE) method was carried out. It was concluded that the method of MAE is not applicable to launch vehicle ascent trajectory optimization due to a lack of a suitable stretched variable. More work was done on the earlier regular perturbation approach using a piecewise analytic zeroth order solution to generate a more accurate approximation. In the meantime, a singular perturbation approach using manifold theory is also under current investigation. Work on a general computational environment based on the use of MACSYMA and the weak Hamiltonian finite element method continued during this period. This methodology is capable of the solution of a large class of optimal control problems

    Significado paleogeográfico de la presencia de gastrópodos marinos en rocas del Jurásico Temprano (Hettangiano medio) de la Formación Pogibshi, Alaska

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    A middle Hettangian marine gastropod assemblage is reported from the Kenai Peninsula of south-central Alaska supplying new paleontological evidence of this group in Lower Jurassic rocks of North America. Pleurotomaria pogibshiensis sp. nov. is described from the middle Hettangian marine succession informally known as Pogibshi formation, being the first occurrence of the genus in the Kenai Peninsula and the oldest occurrence of the genus in present-day Alaska and North America. One species of the genus Lithotrochus, namely Lithotrochus humboldtii (von Buch), is also reported for the first time from the Kenai Peninsula. Lithotrochus has been considered as endemic to South America for a time range from the early Sinemurian to the late Pliensbachian. The newest occurrence of Lithotrochus in rocks of the Pogibshi formation extends the paleobiogeographical and chronostratigraphical distribution of the genus into the present-day Northern Hemisphere. However, the Southern Hemisphere affinities are consistent with the hypothetical interpretations (although supported both by paleobiogeographical and paleomagnetic data) that the Peninsular terrane of south-central Alaska is far-traveled and may have originated at much more southerly paleolatitudes than its present-day position. Two other Early Jurassic caenogastropods typical of the Andean region of South America and of the Tethyan epicontinental seas are described for the first time in the Pogibshi formation, and these are Pseudomelania sp. and Pictavia sp. The new gastropod assemblage reported here shows close affinities with coeval South American and European gastropod faunas, supplying new evidence to interpret their distribution during the Early Jurassic.Una nueva asociación de gastrópodos del Hettangiano medio reconocida en la región sur central de Alaska, aporta nueva evidencia paleontólogica sobre la presencia de este grupo en el Jurásico Inferior de América del Norte. Pleurotomaria pogibshiensis sp. nov. está presente en depósitos marinos del Hettangiano medio de la unidad informalmente conocida como formación Pogibshi, y es la primera ocurrencia del género en la Península Kenai y el registro más antiguo para Alaska y Norte América. Una especie del género Lithotrochus, Lithotrochus humboldtii (von Buch), también se reporta por primera vez en Alaska. Lithotrochus ha sido considerado hasta el momento un género endémico de América del Sur para un intervalo de tiempo, que se extiende desde el Sinemuriano temprano al Pliensbachiano tardío. El nuevo registro de Lithotrochus en rocas de la Formación Pogibshi permite extender su distribución paleobiogeográfica y cronoestratigráfica en el actual hemisferio Norte. Sin embargo, las afinidades con el hemisferio Sur están en consonancia con la interpretación (apoyada por datos paleobiogeográficos y paleomagnéticos) de que el territorio peninsular del centro-sur de Alaska es alóctono y pudo haberse originado en paleolatitudes mucho más al sur que su posición actual. Otros dos caenogastrópodos típicos de la región andina de América del Sur y de los mares epicontinentales del Tethys, tales como Pseudomelania sp. and Pictavia sp., se describen por primera vez para el Jurásico Inferior de la formación Pogibshi. La nueva asociación de gastrópodos aquí descrita muestra estrechas afinidades con faunas coetáneas de América del Sur y Europa, lo que otorga nuevas evidencias para interpretar sus patrones de distribución paleobiogeográfica durante el Jurásico temprano.Fil: Ferrari, Silvia Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Blodgett, Robert B.. Blodgett and Associates; Estados UnidosFil: Hodges, Montana S.. California State University Sacramento; Estados UnidosFil: Hodges, Christopher L.. California State University Sacramento; Estados Unido

    The endothelial protein C receptor rs867186-GG genotype is associated with increased soluble EPCR and could mediate protection against severe malaria

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    The endothelial protein C receptor (EPCR) appears to play an important role in Plasmodium falciparum endothelial cell binding in severe malaria (SM). Despite consistent findings of elevated soluble EPCR (sEPCR) in other infectious diseases, field studies to date have provided conflicting data about the role of EPCR in SM. To better define this role, we performed genotyping for the rs867186-G variant, associated with increased sEPCR levels, and measured sEPCR levels in two prospective studies of Ugandan children designed to understand immunologic and genetic factors associated with neurocognitive deficits in SM including 551 SM children, 71 uncomplicated malaria (UM) and 172 healthy community children (CC). The rs867186-GG genotype was more frequent in CC (4.1%) than SM (0.6%, P = 0.002). The rs867186-G variant was associated with increased sEPCR levels and sEPCR was lower in children with SM than CC (P < 0.001). Among SM children, those who had a second SM episode showed a trend toward lower plasma sEPCR both at initial admission and at 6-month follow-up compared to those without repeated SM (P = 0.06 for both). The study findings support a role for sEPCR in severe malaria pathogenesis and emphasize a distinct role of sEPCR in malaria as compared to other infectious diseases

    Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)

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    The report of an IUPAC Task Group, formed in 2011 on "Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory" (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann--Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions.Comment: Accepted for publication in Pure and Applied Chemistr

    The Threat of Vector-Borne Diseases in Sierra Leone

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    Sierra Leone is vulnerable to a wide range of vector-borne diseases transmitted by mosquitoes, tsetse flies, black flies, and other vectors. Malaria, lymphatic filariasis, and onchocerciasis have posed the greatest threat and have received the most attention in terms of vector control and capacity for diagnosis. However, malaria infection rates remain high, and there is evidence of circulation of other vector-borne diseases, such as chikungunya and dengue, which may go undiagnosed and unreported. The limited understanding of the prevalence and transmission of these diseases restricts the capacity for predicting outbreaks, and impedes the planning of appropriate responses. We review the available literature and gather expert opinions from those working in the country to report on the status of vector-borne disease transmission and control in Sierra Leone, and present an assessment of the threats of these diseases. Our discussions highlight an absence of entomological testing for disease agents and the need for more investment in surveillance and capacity strengthening

    Recommended Isolated-Line Profile for Representing High-Resolution Spectroscopic Transitions (IUPAC Technical Report)

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    The report of an IUPAC Task Group, formed in 2011 on Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile (pCqSD-HCP) should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann-Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions. © 2014 IUPAC & De Gruyte

    Search for Fractional Charges Produced in Heavy-Ion Collisions at 1.9 GeV/nucleon

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    An experiment was performed to capture fractionally charged particles produced in heavy-ion collisions and to concentrate them in samples suitable for analysis by various techniques. Two of the samples so produced have been searched, with use of an automated version of Millikan\u27s oil-drop apparatus. The beam was 56Fe at 1.9 GeV/nucleon, incident on a lead target. Less than one fractional charge per 1.0× 104 Fe-Pb collisions was found to be produced, and, with further assumptions, less than one per 2.0× 106 collisions

    Ampullary cancers harbor ELF3 tumor suppressor gene mutations and exhibit frequent WNT dysregulation

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    The ampulla of Vater is a complex cellular environment from which adenocarcinomas arise to form a group of histopathologically heterogenous tumors. To evaluate the molecular features of these tumors, 98 ampullary adenocarcinomas were evaluated and compared to 44 distal bile duct and 18 duodenal adenocarcinomas. Genomic analyses revealed mutations in the WNT signaling pathway among half of the patients and in all three adenocarcinomas irrespective of their origin and histological morphology. These tumors were characterized by a high frequency of inactivating mutations of ELF3, a high rate of microsatellite instability, and common focal deletions and amplifications, suggesting common attributes in the molecular pathogenesis are at play in these tumors. The high frequency of WNT pathway activating mutation, coupled with small-molecule inhibitors of β-catenin in clinical trials, suggests future treatment decisions for these patients may be guided by genomic analysis

    Heterogeneity of ubiquitin pathology in frontotemporal lobar degeneration: classification and relation to clinical phenotype

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    We have investigated the extent and pattern of immunostaining for ubiquitin protein (UBQ) in 60 patients with frontotemporal lobar degeneration (FTLD) with ubiquitin-positive, tau-negative inclusions (FTLD-U), 37 of whom were ascertained in Manchester UK and 23 in Newcastle-Upon-Tyne, UK. There were three distinct histological patterns according to the form and distribution of the UBQ pathology. Histological type 1 was present in 19 patients (32%) and characterised by the presence of a moderate number, or numerous, UBQ immunoreactive neurites and intraneuronal cytoplasmic inclusions within layer II of the frontal and temporal cerebral cortex, and cytoplasmic inclusions within granule cells of the dentate gyrus; neuronal intranuclear inclusions (NII) of a “cat’s eye” or “lentiform” appearance were present in 17 of these patients. In histological type 2 (16 patients, 27%), UBQ neurites were predominantly, or exclusively, present with few intraneuronal cytoplasmic inclusions within layer II of the cerebral cortex, while in histological type 3 (25 patients, 42%), UBQ intraneuronal cytoplasmic inclusions either within the cortical layer II or in the granule cells of the dentate gyrus, with few or no UBQ neurites, were seen. In neither of these latter two groups were NII present. The influence of histological type on clinical phenotype was highly significant with type 1 histology being associated clinically with cases of frontotemporal dementia (FTD) or progressive non-fluent aphasia (PNFA), type 2 histology with semantic dementia (SD), and type 3 histology with FTD, or FTD and motor neurone disease (MND)
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