5,369 research outputs found

    Effect of gravity on methane-air combustion

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    Analytical and numerical techniques dealing with the theoretical description of the influence of zero and reduced gravitational acceleration on diffusion flames, with a view to improving understanding of fires in space vehicles, were developed in support of experimental work performed in this area. This was done in order to confirm qualitative understanding of the process, to determine the quantitative accuracy of numerical predictions, and to establish a mathematical model of the process for subsequent use as a predictive and exploratory tool. The following results were accomplished: (1) derivation of differential equations and boundary conditions describing the system, (2) details of the computations, using a FORTRAN computer program, for calculating the flow and heat and mass transfer in two dimensions (both steady and unsteady). It was shown that the experimental behavior can be reproduced with fair accuracy, provided that the time step is sufficiently short

    Mangroves as a sustainable coastal defence

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    Mangroves effectively reduce the height of wind and swell waves over short distances (less than 500 m),\ud and can reduce storm surge water levels over greater distances (several kilometres of mangroves). Thus mangroves can\ud contribute to coastal defence strategies. However, their appropriate use depends on a thorough understanding of the\ud conditions under which they can provide these coastal defence services. Here we present a literature review of this\ud topic. Small wind and swell waves can be reduced in height by between 50 and 100% over 500 m of mangroves. Wave\ud reduction largely depends on water depth and vegetation structure and density. However, few measurements are\ud available for the reduction of bigger waves (> 70 cm in height) in deeper water (> 2 m). Storm surge water levels may\ud be reduced by between 5 cm and 50 cm per kilometre of mangrove, based on field measurements and validated\ud numerical models; water level reduction rates depend on the distance from the edge of the mangrove and the forward\ud speed of the cyclone, amongst other factors. Extreme events may severely damage or destroy mangroves, reducing their\ud effectiveness as a coastal defence. The use of mangroves in hybrid engineering can reduce flood risk: for example, a\ud mangrove foreshore in front of a sea wall/dyke will reduce wave impacts on the wall/dyke. The likelihood of waves\ud overtopping the sea wall or walls being breached is thus reduced, with an associated reduction in sea defence\ud maintenance costs. Therefore mangroves can contribute to coastal risk reduction, alongside other risk reduction\ud measures such as sea walls/dykes, early warning systems and evacuation plans. Additionally, mangroves can respond\ud dynamically to rising sea levels, in some cases maintaining their surface elevation with respect to local sea level; thus\ud they may act as a sustainable coastal defence in the face of rising sea levels and changing climatic patterns

    Video recording true single-photon double-slit interference

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    As normally used, no commercially available camera has a low-enough dark noise to directly produce video recordings of double-slit interference at the photon-by-photon level, because readout noise significantly contaminates or overwhelms the signal. In this work, noise levels are significantly reduced by turning on the camera only when the presence of a photon has been heralded by the arrival, at an independent detector, of a time-correlated photon produced via parametric down-conversion. This triggering scheme provides the improvement required for direct video imaging of Young's double-slit experiment with single photons, allowing clarified versions of this foundational demonstration. Further, we introduce variations on this experiment aimed at promoting discussion of the role spatial coherence plays in such a measurement. We also emphasize complementary aspects of single-photon measurement, where imaging yields (transverse) position information, while diffraction yields the transverse momentum, and highlight the roles of transverse position and momentum correlations between down-converted photons, including examples of "ghost" imaging and diffraction. The videos can be accessed at http://sun.iwu.edu/~gspaldin/SinglePhotonVideos.html online.Comment: 7 pages, 8 figure

    PCN62 Cost Impact Modeling of Targeted Molecular Profiling in the Treatment of Colon Cancer

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    Teores de óleo e proteína em grãos de soja, com diferentes manejos de percevejo, da colheita ao armazenamento, utilizando a espectroscopia no infravermelho próximo (NIR).

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    ABSTRACT: The aim was to determine changes in oil and protein content in soybean grain after different stink bugs field managements, on harvest and after of grain storage, using near infrared spectroscopy (NIR). Three stink bugs control managements were used in the soybean crop season as: 1-soybean producer management area; 2-standard integrated pest management area; 3-control management area (no pesticides applied). After harvest and at 3, 6, 9 and 12 months after storage time, samples of grain were taken to analyze oil and protein content at NIR. The experiment was maintained in a room at 25° C and 60% of relative humidity during one year of storage time. The results showed an increase in protein and a decrease in lipid content during storage. The increase of stink bug attack in the field caused an increase in the protein content during storage, however no changes in lipid content occurred. RESUMO: O objetivo do trabalho foi verificar variação nos teores de óleo e proteína em grãos de soja, com diferentes manejos de percevejo, no momento da colheita e após determinado período de armazenamento, utilizando o NIR. Os tratamentos pesquisados neste estudo foram amostras de grãos de várias lavouras de soja e três condições de tratamentos: 1-área do produtor, 2-área com o MIP e 3-área testemunha. O experimento foi conduzido em BODs, sendo as avaliações no ponto zero (colheita), aos três, seis, nove e doze meses de armazenamento. Em condições ideais de armazenamento (25ºC e umidade relativa de 60%), ocorreu um aumento nos teores de proteína e uma diminuição nos teores de lipídios dos grãos de soja ao longo do armazenamento. O aumento de ataque de percevejos ocasionou aumento nos teores de proteína dos grãos de soja durante o armazenamento, entretanto sem alterar os teores de lipídios dos grãos

    Targeted delivery of C/EBPα -saRNA by pancreatic ductal adenocarcinoma-specific RNA aptamers inhibits tumor growth in vivo

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    The 5-year survival rate for pancreatic ductal adenocarcinoma (PDAC) remains dismal despite current chemotherapeutic agents and inhibitors of molecular targets. As the incidence of PDAC constantly increases, more effective multidrug approaches must be made. Here, we report a novel method of delivering antitumorigenic therapy in PDAC by upregulating the transcriptional factor CCAAT/enhancer-binding protein-α (C/EBPα), recognized for its antiproliferative effects. Small activating RNA (saRNA) duplexes designed to increase C/EBPα expression were linked onto PDAC-specific 2′-Fluropyrimidine RNA aptamers (2′F-RNA) - P19 and P1 for construction of a cell type–specific delivery vehicle. Both P19- and P1-C/EBPα-saRNA conjugates increased expression of C/EBPα and significantly suppressed cell proliferation. Tail vein injection of the saRNA/aptamer conjugates in PANC-1 and in gemcitabine-resistant AsPC-1 mouse-xenografts led to reduced tumor size with no observed toxicity. To exploit the specificity of the P19/P1 aptamers for PDAC cells, we also assessed if conjugation with Cy3 would allow it to be used as a diagnostic tool on archival human pancreatic duodenectomy tissue sections. Scoring pattern from 72 patients suggested a positive correlation between high fluorescent signal in the high mortality patient groups. We propose a novel aptamer-based strategy for delivery of targeted molecular therapy in advanced PDAC where current modalities fail

    International Retrospective Chart Review of Treatment Patterns in Severe Familial Mediterranean Fever, Tumor Necrosis Factor Receptor–Associated Periodic Syndrome, and Mevalonate Kinase Deficiency/Hyperimmunoglobulinemia D Syndrome

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    Objective: Periodic fever syndrome (PFS) conditions are characterized by recurrent attacks of fever and localized inflammation. This study examined the diagnostic pathway and treatments at tertiary centers for familial Mediterranean fever (FMF), tumor necrosis factor receptor–associated periodic syndrome (TRAPS), and mevalonate kinase deficiency (MKD)/hyperimmunoglobulinemia D syndrome (HIDS). Methods: PFS specialists at medical centers in the US, the European Union, and the eastern Mediterranean participated in a retrospective chart review, providing de‐identified data in an electronic case report form. Patients were treated between 2008 and 2012, with at least 1 year of followup; all had clinical and/or genetically proven disease and were on/eligible for biologic treatment. Results: A total of 134 patients were analyzed: FMF (n = 49), TRAPS (n = 47), and MKD/HIDS (n = 38). Fever was commonly reported as severe across all indications. Other frequently reported severe symptoms were serositis for FMF patients and elevated acute‐phase reactants and gastrointestinal upset for TRAPS and MKD/HIDS. A long delay from disease onset to diagnosis was seen within TRAPS and MKD/HIDS (5.8 and 7.1 years, respectively) compared to a 1.8‐year delay in FMF patients. An equal proportion of TRAPS patients first received anti–interleukin‐1 (anti‐IL‐1) and anti–tumor necrosis factor (anti‐TNF) biologic agents, whereas IL‐1 blockade was the main choice for FMF patients resistant to colchicine and MKD/HIDS patients. For TRAPS patients, treatment with anakinra versus anti‐TNF treatments as first biologic agent resulted in significantly higher clinical and biochemical responses (P = 0.03 and P < 0.01, respectively). No significant differences in responses were observed between biologic agents among other cohorts. Conclusion: Referral patterns and diagnostic delays highlight the need for greater awareness and improved diagnostics for PFS. This real‐world treatment assessment supports the need for further refinement of treatment practices

    Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults.

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    New neurons continue to be generated in the subgranular zone of the dentate gyrus of the adult mammalian hippocampus. This process has been linked to learning and memory, stress and exercise, and is thought to be altered in neurological disease. In humans, some studies have suggested that hundreds of new neurons are added to the adult dentate gyrus every day, whereas other studies find many fewer putative new neurons. Despite these discrepancies, it is generally believed that the adult human hippocampus continues to generate new neurons. Here we show that a defined population of progenitor cells does not coalesce in the subgranular zone during human fetal or postnatal development. We also find that the number of proliferating progenitors and young neurons in the dentate gyrus declines sharply during the first year of life and only a few isolated young neurons are observed by 7 and 13 years of age. In adult patients with epilepsy and healthy adults (18-77 years; n = 17 post-mortem samples from controls; n = 12 surgical resection samples from patients with epilepsy), young neurons were not detected in the dentate gyrus. In the monkey (Macaca mulatta) hippocampus, proliferation of neurons in the subgranular zone was found in early postnatal life, but this diminished during juvenile development as neurogenesis decreased. We conclude that recruitment of young neurons to the primate hippocampus decreases rapidly during the first years of life, and that neurogenesis in the dentate gyrus does not continue, or is extremely rare, in adult humans. The early decline in hippocampal neurogenesis raises questions about how the function of the dentate gyrus differs between humans and other species in which adult hippocampal neurogenesis is preserved

    Operational experience, improvements, and performance of the CDF Run II silicon vertex detector

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    The Collider Detector at Fermilab (CDF) pursues a broad physics program at Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron delivered 12 fb-1 of integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics analyses undertaken by CDF require heavy flavor tagging with large charged particle tracking acceptance. To realize these goals, in 2001 CDF installed eight layers of silicon microstrip detectors around its interaction region. These detectors were designed for 2--5 years of operation, radiation doses up to 2 Mrad (0.02 Gy), and were expected to be replaced in 2004. The sensors were not replaced, and the Tevatron run was extended for several years beyond its design, exposing the sensors and electronics to much higher radiation doses than anticipated. In this paper we describe the operational challenges encountered over the past 10 years of running the CDF silicon detectors, the preventive measures undertaken, and the improvements made along the way to ensure their optimal performance for collecting high quality physics data. In addition, we describe the quantities and methods used to monitor radiation damage in the sensors for optimal performance and summarize the detector performance quantities important to CDF's physics program, including vertex resolution, heavy flavor tagging, and silicon vertex trigger performance.Comment: Preprint accepted for publication in Nuclear Instruments and Methods A (07/31/2013
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