4,856 research outputs found

    Making On-Demand Routing Efficient with Route-Request Aggregation

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    In theory, on-demand routing is very attractive for mobile ad hoc networks (MANET), because it induces signaling only for those destinations for which there is data traffic. However, in practice, the signaling overhead of existing on-demand routing protocols becomes excessive as the rate of topology changes increases due to mobility or other causes. We introduce the first on-demand routing approach that eliminates the main limitation of on-demand routing by aggregating route requests (RREQ) for the same destinations. The approach can be applied to any existing on-demand routing protocol, and we introduce the Ad-hoc Demand-Aggregated Routing with Adaptation (ADARA) as an example of how RREQ aggregation can be used. ADARA is compared to AODV and OLSR using discrete-event simulations, and the results show that aggregating RREQs can make on-demand routing more efficient than existing proactive or on-demand routing protocols

    Differential transcription profiles inAedes aegyptidetoxification genes after temephos selection

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    The mosquito Aedes aegypti is the main vector of Dengue and Yellow Fever flaviviruses. The organophosphate insecticide temephos is a larvicide that is used globally to control Ae. aegypti populations; many of which have in turn evolved resistance. Target site alteration in the acetylcholine esterase of this species has not being identified. Instead, we tracked changes in transcription of metabolic detoxification genes using the Ae. aegypti ‘Detox Chip’ microarray during five generations of temephos selection. We selected for temephos resistance in three replicates in each of six collections, five from Mexico, and one from Peru. The response to selection was tracked in terms of lethal concentrations. Uniform upregulation was seen in the epsilon class glutathione-S-transferase (eGST) genes in strains from Mexico prior to laboratory selection, while eGSTs in the Iquitos Peru strain became upregulated after five generations of temephos selection. While expression of many carboxyl/cholinesterase esterase (CCE) genes increased with selection, no single esterase was consistently upregulated and this same pattern was noted in the cytochrome P450 monooxygenase (CYP) genes and in other genes involved in reduction or oxidation of xenobiotics. Bioassays using glutathione-S-transferase (GST), CCE and CYP inhibitors suggest that various CCEs instead of GSTs are the main metabolic mechanism conferring resistance to temephos. We show that temephos-selected strains show no cross resistance to permethrin and that genes associated with temephos selection are largely independent of those selected with permethrin in a previous study

    Effect of microencapsulated phenolic compound extracts of Maclura tinctoria (L.) Steud on growth performance and humoral immunity markers of white leg shrimp (Litopenaeus vannamei, Boone, 1931) juveniles

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    Aim of study: The effect of microencapsulated phenolic compound extracts of Maclura tinctoria (MTBE) on growth performance and humoral immunity markers of the white leg shrimp Litopenaeus vannamei juveniles (0.5 ± 0.2 g initial weight) was studied.Area of study: M. tinctoria was collected from Hampolol, Campeche, and Arroyo del Agua, Culiacan, Sinaloa, Mexico.Material and methods: Three MTBE inclusions (0.5, 1, and 2.5 g MTBE/kg, PurinaŸ) were compared with a control commercial feed (PurinaŸ) during 30 days. Nine phenolic acids, nine flavonols, four dihydro-flavonoids, four flavones, and seven unidentified phenolic compounds were determined fin the MTBE using a Perkin ElmerŸ HPLC chromatograph and diode array-detection.Main results: The mean concentrations of total phenolic compounds, total flavonoid compounds, and condensed tannins were 198.05 ± 5.59 mg gallic acid equivalent (GAE) g-1 dw, 78.57 ± 1.80 quercetin equivalent g-1, and 28.32 ± 0.33 mg epicatechin equivalent g-1, respectively. The ferric reducing antioxidant power and the total antioxidant capacity, respectively, averaged 28.32 mg GAE mL-1 and 10.9 mg ascorbic acid equivalent mL-1. Survival, weight gain, and specific growth rate of L. vannamei were similar among the experimental diets. The dietary inclusion of MTBE at 0.5 g/kg of food showed significant higher (p < 0.05) plasma hemocyte lysate protein (1.35 ± 0.055 ”g mL-1), prophenoloxidase (0.47 ± 0.15, Abs. 492 nm), and superoxide anion (O2.-) activity (0.21 ± 0.07, Abs. 630 nm).Research highlights: The supplementation of MTBE at 0.5 g/kg of food could be considered as a potential alternative additive for L. vannamei diet in the juvenile production, since it improved the response of the humoral immunity markers at post larval life stages, when cultivated shrimp are more susceptible to be infected by pathogens

    BUSINESS PRESENTATIONS, LABELING AND INGREDIENTS OF PRODUCTS SOLD AS HUMAN FOOD RATION

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    A Ração Humana (RH) foi um produto formulado no Brasil e destinado aos consumidores que desejam benefĂ­cios Ă  saĂșde providos por alimentos. Este trabalho teve como objetivo caracterizar apresentaçÔes comerciais, rotulagem e ingredientes de produtos comercializados como RH. Uma unidade de cada RH disponĂ­vel em Curitiba-PR (Brasil) foi adquirida e analisada individualmente por dois avaliadores. Foram identificadas apresentaçÔes industriais e artesanais, ofertadas com diversas nomenclaturas, como: combinação de cereais integrais, mistura Ă  base de cereais, mistura para preparo de bebida, alĂ©m de apresentaçÔes artesanais que nĂŁo denominavam o produto. A maioria das RH omitia informaçÔes sobre registro ou indicavam sua isenção. TrĂȘs amostras apresentaram alegaçÔes terapĂȘuticas ou medicamentosas vetadas para alimentos (maior saciedade, regulação intestinal e melhor desempenho fĂ­sico). Amostras artesanais nĂŁo informavam sobre prazo de validade e armazenamento. Somadas, as apresentaçÔes de RH totalizaram 23 ingredientes demonstrando falta de padronização. Foram observados componentes proibidos em alimentos (Ginko biloba, ginseng e isoflavonas) e uso de novos ingredientes (farinhas de casca de maracujĂĄ, feijĂŁo branco, cenoura e banana verde). A maioria das RH (H) continha açĂșcar mascavo limitando seu uso por diabĂ©ticos. A diversidade de ingredientes resulta em variação na composição quĂ­mica e valor calĂłrico, entre 64 e 124 Kcal/porção, alĂ©m de impossibilitar a classificação do produto segundo a legislação. A oferta da RH deve ser acompanhada pelas agĂȘncias reguladoras objetivando evitar prejuĂ­zos Ă  saĂșde e o consumo estimulado por alegaçÔes de saĂșde incoerentes para alimentos, sobretudo produtos isentos de registro

    Naturally light right-handed neutrinos in a 3-3-1 Model

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    In this work we show that light right-handed neutrinos, with mass in the sub-eV scale, is a natural outcome in a 3-3-1 model. By considering effective dimension five operators, the model predicts three light right-handed neutrinos, weakly mixed with the left-handed ones. We show also that the model is able to explain the LSND experiment and still be in agreement with solar and atmospheric data for neutrino oscillation.Comment: About 5 pages, no-figure

    Primary Angioplasty in a Catastrophic Presentation: Acute Left Main Coronary Total Occlusion—The ATOLMA Registry

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    Objectives. To determine the outcome predictors of in-hospital mortality in acute total occlusion of the left main coronary artery (ATOLMA) patients referred to emergent angioplasty and to describe the clinical presentation and the long-term outcome of these patients.Background. ATOLMA is an uncommon angiographic finding that usually leads to a catastrophic presentation. Limited and inconsistent data have been previously reported regarding true ATOLMA, yet comprehensive knowledge remains scarce.Methods. This is a multicenter retrospective cohort that includes patients presenting with myocardial infarction due to a confirmed ATOLMA who underwent emergency percutaneous coronary intervention (PCI).Results. In the period of the study, 7930 emergent PCI were performed in the five participating centers, and 46 of them had a true ATOLMA (0.58%). At admission, cardiogenic shock was present in 89% of patients, and cardiopulmonary resuscitation was required in 67.4%. All the patients had right dominance. Angiographic success was achieved in 80.4% of the procedures, 13 patients (28.2%) died during the catheterization, and the in-hospital mortality rate was 58.6% (27/46). At one-year and at the final follow-up, 18 patients (39%) were alive, including four cases successfully transplanted. Multivariate analysis showed that postprocedural TIMI flow was the only independent predictor of in-hospital mortality (OR 0.23, (95% CI 0.1-0.36),p<0.001).Conclusions. Our study confirms that the clinical presentation of ATOLMA is catastrophic, presenting a high in-hospital mortality rate; nevertheless, primary angioplasty in this setting is feasible. Postprocedural TIMI flow resulted as the only independent predictor of in-hospital mortality. In-hospital survivors presented an encouraging outcome. ATOLMA and left dominance could be incompatible with life

    Gold nanoparticle coated silicon tips for Kelvin probe force microscopy in air

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    Abstract The tip apex dimensions and geometry of the conductive probe remain the major limitation to the resolution of Kelvin probe force microscopy (KPFM). One of the possible strategies to improve the spatial resolution of surface potential images consists in the development of thinner and more durable conductive tips. In an effort to improve the lateral resolution of topography and surface potential maps, we have evaluated high aspect ratio conductive tips created by depositing gold nanoparticles on standard silicon tips. Besides the already known general topographic resolution enhancement offered by these modified tips References [1] L

    A survey of performance enhancement of transmission control protocol (TCP) in wireless ad hoc networks

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    This Article is provided by the Brunel Open Access Publishing Fund - Copyright @ 2011 Springer OpenTransmission control protocol (TCP), which provides reliable end-to-end data delivery, performs well in traditional wired network environments, while in wireless ad hoc networks, it does not perform well. Compared to wired networks, wireless ad hoc networks have some specific characteristics such as node mobility and a shared medium. Owing to these specific characteristics of wireless ad hoc networks, TCP faces particular problems with, for example, route failure, channel contention and high bit error rates. These factors are responsible for the performance degradation of TCP in wireless ad hoc networks. The research community has produced a wide range of proposals to improve the performance of TCP in wireless ad hoc networks. This article presents a survey of these proposals (approaches). A classification of TCP improvement proposals for wireless ad hoc networks is presented, which makes it easy to compare the proposals falling under the same category. Tables which summarize the approaches for quick overview are provided. Possible directions for further improvements in this area are suggested in the conclusions. The aim of the article is to enable the reader to quickly acquire an overview of the state of TCP in wireless ad hoc networks.This study is partly funded by Kohat University of Science & Technology (KUST), Pakistan, and the Higher Education Commission, Pakistan
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