5,066 research outputs found

    Kinematic, coordinative and efficiency parameters of physically impaired swimmers at maximum aerobic power speed

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    In paralympic swimming, the biomechanical parameters related to performance are effectively determined according to the potentialities and peculiarities of each athlete. However, a clear integrated approach to these parameters for swimmers with physical disabilities at the speed of maximum oxygen uptake (vV̇O2max) is still practically non-existent. Objective: The purpose of this study was twofold: (i) to assess kinematic, coordinative and efficiency parameters measured at vV̇O2max in swimmers with physical impairments; and (ii) to correlate these biomechanical parameters with the time for a 200 m maximum test. Methods: Eleven swimmers with physical disabilities (seven males and four females) were assessed at vV̇O2max with support from a three-dimensional kinematic method. The performance parameters analysed were: (i) kinematic - stroke rate (SR), stroke length (SL), average swimming speed (SS) and intra-cyclic velocity variation (IVV); (ii) coordinative - index of coordination (IdC) and adapted index of coordination (IdCadapt); and (iii) swimming efficiency - propelling efficiency (çp). Results: The overall results showed high dispersion and wide confidence intervals for the kinematic and coordinative variables. The mean and standard deviation of vV̇O2max and V̇O2 at the same intensity were 0.90 ± 0.13 m/s and 38.2 ± 8.3 ml/kg/min, respectively. Conclusion: Swimmers with less significant impact of physical disability on specific swimming tasks presented higher SL, SS and çp. The IVV was higher in swimmers with a greater impact of disability on conducting specific competitive swimming tasks. In general, the catch-up inter-arm coordination model is adopted

    ESTIMATION OF CORROSION RATES BY RUN COMPARISON: A STOCHASTIC SCORING METHODOLOGY

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    ABSTRACT Pipeline operators used to map and quantify corrosion damage along their aging pipeline systems by carrying out periodical in-line metal-loss inspections. Comparison with the data sets from subsequent runs of such inspections is one of the most reliable techniques to infer representative corrosion growth rates throughout the pipeline length, within the period between two inspections. Presently there are two distinct approaches to infer corrosion rates based on multiple in-line inspections: individual comparison of the detected defective areas (quantified by more than one inspection), and comparison between populations. The former usually requires a laborious matching process between the run-data sets, while the drawback of the latter is that it often fails to notice hot-spot areas. The object of this work is to present a new methodology which allows quick data comparison of two runs, while still maintaining local distinct characteristics of the corrosion process severity. There are three procedures that must be performed. Firstly, ILI metal-loss data set should be submitted to a filtering/adjustment process, taking into consideration the reporting threshold consistency; the possible existence of systematic bias and corrosion mechanisms similarity. Secondly, the average metal-loss growth rate between inspections should be determined based on the filtered populations. Thirdly, the defects reported by the latest inspection should have their corrosion growth rates individually determined as a function of the mean depth values of the whole population and in the defect neighborhood. The methodology allows quick and realistic damage-progression estimates, endeavoring to achieve more cost-effective and reliable strategies for the integrity management of aged corroded systems. Model robustness and general feasibility is demonstrated in a real case study

    New approaches for growth improvement in pejerrey Odontesthes bonariensis (Valenciennes, 1835) culture (Atherinomorpha: Atherinopsidae)

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    The pejerrey is the most important recreational species in shallow temperate lakes and reservoirs of Argentina and the attempts to develop its culture have started a century ago. A common constraint of pejerrey aquaculture is its poor growth under traditional intensive rearing methods. The aim of this study was to assess by innovative culture methods for pejerrey if the species might maintain high growth rates, and to discuss if growth rate is a critical constraint for the species culture. Four floating cages were installed at La Salada de Monasterio lake and each one was stocked with 300 juveniles. From January through March all fish were exposed to natural zooplankton as food source, whereas from April to September two cages were supplied daily with artificial food. The fish exposed to artificial supplementary diets exhibited significantly higher growth rates than those in the control cages, and exceeded the values known in pejerrey culture. The results suggest that the species potential growth is not fully exploited by common intensive methods and it can be improved by semi-intensive techniques. Indeed, if a better understanding of the species nutritional requirements is achieved, pejerrey culture could be enhanced.El pejerrey es la especie de mayor importancia deportiva en lagos someros templados y embalses de Argentina y el desarrollo de su acuicultura data de cien años atrás. Un impedimento común para el desarrollo de la acuicultura del pejerrey es el pobre crecimiento que manifiesta bajo cultivo intensivo. El objetivo de este estudio fue evaluar la posibilidad de alcanzar y mantener altas tasas de crecimiento en el pejerrrey mediante cultivo semi-intensivo. Se instalaron cuatro jaulas flotantes en la laguna La Salada de Monasterio, sembrándose cada una con 300 juveniles (10.22 ±0.38cm; 6.52 ±0.82g). Desde enero hasta marzo los peces se alimentaron con el zooplancton natural de la laguna, mientras que desde abril hasta septiembre dos jaulas fueron suplementadas diariamente con alimento balanceado, dejándose las otras dos como controles. Los peces bajo dietas suplementadas mostraron crecimientos significativamente superiores (17.5 ±0.98cm; 41.05 ±8.55g) a los de las jaulas control (15.02 ±0cm ; 23.5 ±0.84g), excediendo incluso los conocidos en el cultivo de pejerrey en períodos similares. Los resultados obtenidos sugieren que el potencial de crecimiento del pejerrey no está siendo explotado en su totalidad bajo las técnicas de cultivo tradicionales y puede mejorarse mediante el cultivo semi-intensivo. En consecuencia es necesaria una mejor comprensión de los requerimientos nutricionales del pejerrey para incrementar sus tasas de crecimiento y así mejorar su cultivo.Fil: Solimano, Patricio José. Universidad Nacional de Rio Negro. Sede Andina. Escuela de Producción, Tecnología y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garcia de Souza, Javier Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Maiztegui, Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Baigún, Claudio Rafael M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Colautti, Dario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

    Population responses of common carp Cyprinus carpio to floods and droughts in the Pampean wetlands of South America

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    Common carp (Cyprinus carpio) is a global invader that exhibits a wide distribution in Argentina, particularly in shallow lakes and wetlands of the Pampean region. The hydrological conditions of these environments are driven by variations in annual precipitation that determine inter annual changes in water levels leading to flood-drought cycles. The present study focused on understanding the C. carpio population responses to annual rainfall regime and long-term flood and drought events in the Ajó wetlands located in the east of the Pampean region. The results of a two-year biological sampling program showed that C. carpio feeding rate, reproduction, condition, and recruitment were associated with the hydrological cycle. Otolith derived age structure of the population and back-calculated recruitment strength revealed that extraordinary flooding events generated strong cohorts while dry years resulted in low recruitment. Its long-life span (maximum 14 years in Ajó) coupled with a high fecundity, and broad diet allows C. carpio to persist in refugia during dry years and capitalize on wet years when inundation of the floodplain enhances recruitment and facilitates spread. Management and control strategies for this invader should therefore incorporate hydrological variability by promoting intensive removal campaigns during dry years when populations are dominated by large fish confined in remnant water-bodies and, during wet years, carp harvest fisheries should be promoted to reduce population density when increased connectivity is likely to facilitate spread.Fil: Maiztegui, Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentina. South African Institute For Aquatic Biodiversity; SudáfricaFil: Baigún, Claudio Rafael M.. Universidad Nacional de San Martín. Instituto de Investigación en Ingeniería Ambiental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garcia de Souza, Javier Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Weyl, Olaf L. F.. South African Institute for Aquatic Biodiversity; SudáfricaFil: Colautti, Dario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

    Evaluación de modelos del crecimiento en diferentes condiciones de cultivo de pejerrey (Odontesthes bonariensis)

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    The pejerrey is one of the most important temperate native freshwater species of Argentina. Its culture is mainly done intensively and in recent years is being developed in floating cages in several Pampean lakes under semi-intensive and extensive conditions. To evaluate the growth of fish under different culture methodologies several models are used, most of which are based on the specific growth rate (SGR). The objective of this study is to compare how the SGR of pejerrey responds under different culture methods and generate a theoretical model to predict the growth that the species can reach. To carry out the models a data base was made with the available data of intensive, extensive and semi-intensive culture, to which an exponential and polynomial models were adjusted by the method of least squares and then the expected growth was simulated using the model that better fits. From the results it was observed that the polynomial model presented the best fit to different methods of culture. In all cases the models reflected the seasonality in the growth rates exhibited by the species, where SGR was lowest in winter and highest in spring. The growth simulation models also show that the semi-intensive culture could produce greater weight than other methods. Under these conditions, fish obtain zooplankton from the environment incorporating essential elements from its natural food source. This suggests that it is possible to improve the sizes of fish by using techniques that also incorporate natural food or its equivalent in the composition of the artificial diets.Fil: Solimano, Patricio José. Universidad Nacional de Rio Negro. Sede Atlantica. Escuela de Producción, Tecnología y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garcia de Souza, Javier Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Maiztegui, Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Bazzani, Julia Lucia. Universidad Nacional de Rio Negro. Sede Atlantica. Escuela de Producción, Tecnología y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Baigún, Claudio Rafael M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Colautti, Dario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

    Tympanic paragangliomas: case reports

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    Glomus tumors, also called paragangliomas, originate from nonchromaffin cells. The tumor is typically vascular and grows from capillary and pre-capillary vessels in-between epithelial cells. It is worth mentioning that the most common symptoms are pulsating tinnitus and hearing loss. Imaging studies (CT and MRI) are necessary for diagnosis. This paper shows five patients seen at the Hospital between 1995 and 2001 presenting glomus tympanicum. Women were most commonly affected, and the age ranged from 48 to 60 years (mean age of 50 years). The most common complaints were pulsating tinnitus and hearing loss. All patients were treated surgically.Os tumores glômicos, também chamados de paragangliomas, são formados por células não cromafins. O tumor é tipicamente vascular formado por vasos capilares e pré-capilares, interposto por células epiteliais. Para a sua abordagem inicial, deve-se ressaltar que os sintomas mais comumentes encontrados são o zumbido pulsátil e hipoacusia. A investigação através de imagem (tomografia computadorizada e ressonância magnética) se faz necessária. Apresentaremos neste trabalho 5 pacientes portadores de paragangliomas timpânicos atendidos no Hospital (de 1995 a 2001). O sexo predominante foi o feminino, a idade variou de 48 a 60 anos, com média de 50 anos. A queixa predominante foi o zumbido pulsátil e a hipoacusia. A conduta foi cirúrgica em todos os casos.Hospital Paulista de OtorrinolaringologiaUNIFESP-EPMUNIFESP, EPMSciEL

    Los peces de las lagunas de la ecorregión Pampeana

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    La ecorregión Pampeana se caracteriza por la presencia de numerosas lagunas. Éstas son el hábitat de una abundante comunidad de peces cuyas dinámicas poblacionales están estrechamente vinculadas a los inestables eventos hídricos de los sistemas, que imponen condiciones de vida gobernadas por amplias variaciones físico-químicas del medio y una disponibilidad de recursos muy variable. El funcionamiento de muchos de estos lagos someros tiene una estrecha relación con los ríos que atraviesan la región, principalmente el río Salado, no sólo en lo referente a su hidrología sino también en lo biológico. En el caso del río Salado, se trata del principal curso de agua de la región pampeana, y sirve de vía de circulación para las especies acuáticas entre el Río de la Plata y muchas de las lagunas que conforman el sistema; otra gran cantidad de lagunas como La Barrancosa no se conectan directamente con este río pero durante períodos de inundación suelen vincularse a otros cuerpos de agua generándose vías de intercambio de flora y fauna entre ellos.Fil: Colautti, Dario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Garcia de Souza, Javier Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Baigún, Claudio Rafael M.. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Instituto de Investigación en Ingeniería Ambiental; Argentin

    Effects of partial root-zone drying irrigation on cluster microclimate and fruit composition of field-grown Castelão grapevines

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    The partial root-zone drying (PRD) irrigation technique has been proposed for viticulture as a possible way to save water without compromising yield. Half of the plant root system is slowly dehydrating whereas the other half is irrigated; after about two weeks the opposite side of vines is irrigated. A PRD irrigation system (50 % of the crop evapotranspiration - ETc) was installed in a vineyard (Vitis vinifera L. cv. Castelão) in Southern Portugal and compared with two other irrigation systems, deficit irrigation, DI (50 % ETc) and full irrigation, FI (100 % ETc), as well as with non-irrigated vines (NI). Water was applied twice a week, from fruit set (mid-June) until one week before harvest (September 3). While FI vines remained well watered during the ripening period, a severe water stress developed in NI plants. PRD and DI vines exhibited mild water deficits during the same period. A significant decrease in vegetative growth (shoot weight, pruning weight, leaf layer number and percentage of water shoots) was observed in NI and PRD vines when compared to DI and FI. In denser canopies (FI and DI) berry temperature was always lower than that of the more open ones (NI and PRD). The higher degree of cluster exposition in PRD and NI had a positive influence on berry composition due to temperature and incident radiation, leading to higher concentrations of anthocyanins and total phenols in the berry skin compared to DI and FI vines. Irrigation did not significantly affect berry sugar accumulation and pH in berries. Compared to FI, PRD and DI treatments water use efficiency (the amount of fruit produced per unit of water applied) was doubled since at the same yield the amount of water applied, was reduced by 50 %.
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