6,937 research outputs found

    Development of a PCR-RFLP marker to genetically distinguish Prosorhynchus crucibulum and Prosorhynchus aculeatus

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    The cercariae stages of Prosorhynchus crucibulum and Prosorhynchus aculeatus are morphologically indistinguishable. However, the differentiation of these two species is crucial to understand the transmission dynamics between these primary hosts (mussels) and the secondary hosts (fish). In this way, the objective of this study is to develop an accurate molecular identification too] to differentiate the cercariae stage of P. crucibulum and P. aculeatus. We targeted the 18S nuclear ribosomal DNA region by PCR amplification and sequenced this amplicon. By generating these sequences, we developed a RFLP tool with the use of the enzymes Hincll and FokI that produced different restriction profiles between P. crucibulum and P. aculeatus. Each enzyme generated different-sized fragments specific to the species examined and no cross-reaction between the species was detected in their restriction pattern. By sequencing, no intraspecific-polymorphism was detected since there is 100% homology among A aculeatus or A crucibulum. These results indicate that PCR-linked restriction analysis of the 18S rDNA region provided us with rapid and reliable molecular tools for distinction of the cercariae of these species. The sequences generated were deposited in GenBank accession numbers for P. crucibulum cercariae (FJ463407, FJ463408 and FJ463409) and adult worm (FJ429096, FJ429097), and for A aculeatus adult (FJ429094 and FJ429095). (C) 2009 Elsevier Ireland Ltd. All rights reserved

    Seroprevalence of Toxoplasmosis in Blood Donors: An Investigation from the Endemicity. Non-systematic Review

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    Toxoplasma gondii is an intracellular protozoan that causes toxoplasmosis, the most common parasitic disease in the world, which infects humans and animals. It is transmitted through cat feces through the process of excretion and ingestion of oocysts. Humans become infected by eating improperly washed vegetables, raw or undercooked meat, contaminated water, the soil or area where the cat defecates, or by transfusing infected blood. The study aims to identify, through scientific evidence, the seroprevalence of T. gondii in blood donors, considering its global endemicity. A non-systematic documentary review was used for searching articles worldwide on the topic of T. gondii seroprevalence in blood donors, in different databases such as SciELO, Google Academics, etc. A total of 27 articles that had the required information; grouping the seroprevalence results by region, obtained positive IgG and IgG + IgM. Calculating the prevalence, it was identified in Asia at 7.8%, America 32.8%, Africa 40.7%, Oceania 34%, and Europe 38.1%. In conclusion, it is convenient to carry out this type of study in each country to verify the prevalence and, in addition, to determine the incidence of infection in blood donors to calculate the risk of transmission. Keywords: Toxoplasma, seroepidemiologic studies, antibodies, immunoglobulin G, immunoglobulin M, blood donors. Resumen Introducción: Toxoplasma gondii en un protozoo intracelular causante de la toxoplasmosis, la enfermedad parasitaria más frecuente del mundo la cual infecta a humanos y animales, se trasmite por medio de las heces de los gatos mediante el proceso de excreción e ingestión de los ooquistes. Los humanos se infectan al ingerir vegetales mal lavados, carne cruda o poco cocida, agua contaminada, el suelo o área donde defeca el gato, o al transfundir sangre infectada. Objetivo: identificar mediante evidencias científicas la seroprevalencia de T. gondii en donantes de sangre, considerando su endemicidad global. Metodología: se empleó una revisión no sistemática, documental realizando la búsqueda de artículos a nivel mundial del tema seroprevalencia de T. gondii en donantes de sangre, en diferentes bases como SciELO, Google Academics, etc. Resultados: un total de 27 artículos que contaron con la información requerida; agrupando los resultados de seroprevalencia por región, anticuerpos positivos IgG e IgG + IgM. Calculando la prevalencia se identificó, en Asia 7,8%; América 32,8%; África 40,7%; Oceanía 34% y Europa 38,1%. Conclusión: es conveniente realizar este tipo de estudio en cada país para comprobar la prevalencia y, además, determinar la incidencia de la infección en donantes de sangre para calcular el riesgo de transmisión. Palabras Clave: Toxoplasma, estudios seroepidemiológicos, anticuerpos, inmunoglobulina G, inmunoglobulina M, donantes de sangre

    The Performance of Lag Selection and Detrending Methods for HEGY Seasonal Unit Root Tests

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    This paper analyzes two key issues for the empirical implementation of parametric seasonal unit root tests, namely generalized least squares (GLS) versus ordinary least squares (OLS) detrending and the selection of the lag augmentation polynomial. Through an extensive Monte Carlo analysis, the performance of a battery of lag selection techniques is analyzed, including a new extension of modified information criteria for the seasonal unit root context. All procedures are applied for both OLS and GLS detrending for a range of data generating processes, also including an examination of hybrid OLS-GLS detrending in conjunction with (seasonal) modified AIC lag selection. An application to quarterly U.S. industrial production indices illustrates the practical implications of choices made

    Semi-parametric seasonal unit root tests

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    We extend the M class of unit root tests introduced by Stock (1999, Cointegration, Causality and Forecasting. A Festschrift in Honour of Clive W.J. Granger. Oxford University Press), Perron and Ng (1996, Review of Economic Studies 63, 435–463) and Ng and Perron (2001, Econometrica 69, 1519–1554) to the seasonal case, thereby developing semi-parametric alternatives to the regression-based augmented seasonal unit root tests of Hylleberg, Engle, Granger, and Yoo (1990, Journal of Econometrics 44, 215–238). The success of this class of unit root tests to deliver good finite sample size control even in the most problematic (near-cancellation) case where the shocks contain a strong negative moving average component is shown to carry over to the seasonal case as is the superior size/power trade-off offered by these tests relative to other available tests

    Vestibular loss disrupts visual reactivity in the alpha EEG rhythm.

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    The alpha rhythm is a dominant electroencephalographic oscillation relevant to sensory-motor and cognitive function. Alpha oscillations are reactive, being for example enhanced by eye closure, and suppressed following eye opening. The determinants of inter-individual variability in reactivity in the alpha rhythm (e.g. changes with amplitude following eye closure) are not fully understood despite the physiological and clinical applicability of this phenomenon, as indicated by the fact that ageing and neurodegeneration reduce reactivity. Strong interactions between visual and vestibular systems raise the theoretical possibility that the vestibular system plays a role in alpha reactivity. To test this hypothesis, we applied electroencephalography in sitting and standing postures in 15 participants with reduced vestibular function (bilateral vestibulopathy, median age = 70 years, interquartile range = 51-77 years) and 15 age-matched controls. We found participants with reduced vestibular function showed less enhancement of alpha electroencephalography power on eye closure in frontoparietal areas, compared to controls. In participants with reduced vestibular function, video head impulse test gain - as a measure of residual vestibulo-ocular reflex function - correlated with reactivity in alpha power across most of the head. Greater reliance on visual input for spatial orientation ('visual dependence', measured with the rod-and-disc test) correlated with less alpha enhancement on eye closure only in participants with reduced vestibular function, and this was partially moderated by video head impulse test gain. Our results demonstrate for the first time that vestibular function influences alpha reactivity. The results are partly explained by the lack of ascending peripheral vestibular input but also by central reorganisation of processing relevant to visuo-vestibular judgements

    Experimental study of formwork tightness as a function of rheological properties of SCC

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    Several studies relating formwork pressure to rheology exist, however the relationship between rheology and leakage through formwork joints remains to be investigated. In practice, standard documents are used to define formwork tightness requirements, typically using a qualitative approach. To try bridge this gap in knowledge, we developed a test set-up to study tightness of formwork joints under pressure as a function of varying rheological properties. Coupled with standard rheology tests, this new test set-up provides means of linking flow rate, formwork pressure, flow area, and the rheological properties. The study seeks to provide insight on measurable governing parameters and thus inform formwork tightness requirements in a more quantifiable manner. This paper presents a test set-up designed to study the flow of fresh paste through small openings. It highlights a preliminary study on the pressure-driven flow of limestone paste through a bottom orifice in a cylindrical container. While this new device may not be directly representative of the actual conditions in formwork, it provides a good base for a fundamental study that can then be extrapolated to a more representative test operation. Preliminary results show a linear relationship between the flow rate and the applied pressure. The results also show that increasing the flow area by a factor of 2.33 had a higher impact than an increase in yield stress and viscosity by a factor of 2.54 and 3.80 respectively. However, more tests need to be carried out to obtain clear trends

    A novel multivariate STeady-state index during general ANesthesia (STAN)

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    The assessment of the adequacy of general anesthesia for surgery, namely the nociception/anti-nociception balance, has received wide attention from the scientific community. Monitoring systems based on the frontal EEG/EMG, or autonomic state reactions (e.g. heart rate and blood pressure) have been developed aiming to objectively assess this balance. In this study a new multivariate indicator of patients' steady-state during anesthesia (STAN) is proposed, based on wavelet analysis of signals linked to noxious activation. A clinical protocol was designed to analyze precise noxious stimuli (laryngoscopy/intubation, tetanic, and incision), under three different analgesic doses; patients were randomized to receive either remifentanil 2.0, 3.0 or 4.0 ng/ml. ECG, PPG, BP, BIS, EMG and [Formula: see text] were continuously recorded. ECG, PPG and BP were processed to extract beat-to-beat information, and [Formula: see text] curve used to estimate the respiration rate. A combined steady-state index based on wavelet analysis of these variables, was applied and compared between the three study groups and stimuli (Wilcoxon signed ranks, Kruskal-Wallis and Mann-Whitney tests). Following institutional approval and signing the informed consent thirty four patients were enrolled in this study (3 excluded due to signal loss during data collection). The BIS index of the EEG, frontal EMG, heart rate, BP, and PPG wave amplitude changed in response to different noxious stimuli. Laryngoscopy/intubation was the stimulus with the more pronounced response [Formula: see text]. These variables were used in the construction of the combined index STAN; STAN responded adequately to noxious stimuli, with a more pronounced response to laryngoscopy/intubation (18.5-43.1 %, [Formula: see text]), and the attenuation provided by the analgesic, detecting steady-state periods in the different physiological signals analyzed (approximately 50 % of the total study time). A new multivariate approach for the assessment of the patient steady-state during general anesthesia was developed. The proposed wavelet based multivariate index responds adequately to different noxious stimuli, and attenuation provided by the analgesic in a dose-dependent manner for each stimulus analyzed in this study.The first author was supported by a scholarship from the Portuguese Foundation for Science and Technology (FCT SFRH/BD/35879/2007). The authors would also like to acknowledge the support of UISPA—System Integration and Process Automation Unit—Part of the LAETA (Associated Laboratory of Energy, Transports and Aeronautics) a I&D Unit of the Foundation for Science and Technology (FCT), Portugal. FCT support under project PEst-OE/EME/LA0022/2013.info:eu-repo/semantics/publishedVersio

    Fractional Schr\"odinger equation and time dependent potentials

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    We investigate the solutions for a time dependent potential by considering two scenarios for the fractional Schr\"odinger equation. The first scenario analyzes the influence of the time dependent potential in the absence of the kinetic term. We obtain analytical and numerical solutions for this case by considering the Caputo fractional time derivative, which extends Rabi's model. In the second scenario, we incorporate the kinetic term in the Schr\"odinger equation and consider fractional spatial derivatives. For this case, we analyze the spreading of the Gaussian wave package under the action of the time and spatial fractional differential operators

    Intermittent Pringle Maneuver and Hepatic Function: Perioperative Monitoring by Noninvasive ICG-Clearance

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    BACKGROUND: Intermittent Pringle maneuver or selective portal clamping often are used to control inflow during parenchymal liver transection. This study was designed to determinate whether these maneuvers are associated with adverse hepatic function. METHODS: Resection was performed without portal clamping in 17 patients (group 1). Selective continuous portal clamping was performed in 11 patients (group 2) and the remaining 33 patients (group 3) had intermittent nonselective portal clamping (occlusion of the main portal trunk). The centers' protocol for total portal occlusion is 15-min occlusion alternated with 5-min reperfusion in patients with normal liver parenchyma or 10 min alternated with 5 min in patients with abnormal parenchyma. ICG elimination tests were conducted concurrently using a noninvasive monitor that tracks the plasma disappearance rate (PDR-ICG-%/min) and 15-min retention rate after administration (ICG-R15-%). RESULTS: There was no statistically difference between the three studied groups in terms of sequential changes of ICG-PDR (p < 0.625) or ICG-R15 (p < 0.398). CONCLUSIONS: Our study indicates that 15 min of intermittent Pringle maneuver or selective hemihepatic continuous portal clamping are safe methods of vascular control during liver resection, with no adverse effects on hepatocellular function

    Conical Defects in Higher Spin Theories

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    We study conical defect geometries in the SL(N) Chern-Simons formulation of higher spin gauge theories in AdS_3. We argue that (for N\geq 4) there are special values of the deficit angle for which these geometries are actually smooth configurations of the underlying theory. We also exhibit a gauge in which these geometries can be viewed as wormholes interpolating between two distinct asymptotically AdS_3 spacetimes. Remarkably, the spectrum of smooth SL(N,C) solutions, after an appropriate analytic continuation, exactly matches that of the so-called "light primaries" in the minimal model W_N CFTs at finite N. This gives a candidate bulk interpretation of the latter states in the holographic duality proposed in [1].Comment: 38 page
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