388 research outputs found

    Reduced lipoperoxidation in high-performance athletes with mental retardation by a mixed protocol based on exercise and supplementation

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    Individuals with mental retardation generally present high levels of oxidative stress. Further it is widely accepted that high physical performance may be associated to oxidative damage. The present study was undertaken to ascertain the influence of a mixed protocol based on regular exercise and antioxidant supplementation in lipoperoxidation in athletes with mental retardation. Fifty-five high-performance athletes with mental retardation from Special Olympics volunteered for this study (21.6±1.8 years-old). Fourty were randomly included in experimental group to perform a 6-weeks protocol, including exercise (low-moderate intensity aerobic exercise before breakfast 3 times per week) and supplementation (1g ascorbic acid + 400 UI α-tocopherol 6 times per week). Control group included 15 age, sex, trained and BMI-matched athletes with mental retardation who did not perform the mixed protocol. Written informed consent was obtained. The protocol was approved by an institutional ethic committee. Plasmatic (please first define the abbreviation) MDA were determined by high performance liquid chromatography (HPLC) with fluorimetric detection as described elsewhere, 72-hours before starting the protocol (pre-test) and after its ending (post-test). When compared to baseline MDA levels were decreased significantly after our 6-weeks protocol (0.50±0.12 vs 0.36±0.09 μmol·l-1; p\u3c0.05). No changes were reported in controls. It was concluded that a 6-weeks mixed protocol improved significantly lipoperoxidation in athletes with mental retardation. Further studies on this topic are highly required

    Estimation and comparison of benefits due to feeding hay and silage during the dry season on commercial dual-purpose cattle production systems in Honduras and Costa Rica

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    Smallholders with dual-purpose cattle production systems in most Central America experience a shortage of forages during the dry season (4-8 month. As a result, substantially lower milk production and weight gain occurs. Dual-purpose operations seeking to maximize milk and beef production in the dry season can produce and feed hay or silage to their livestock. The increase in milk and beef production due to feeding hay or silage during the dry season on commercial dual-purpose cattle productions systems, the production costs of making silage or hay and the benefits as a result of feeding silage or hay are estimated and compared in Honduras and Costa Rica. Due to feeding silage or hay, farmers in Honduras and Costa Rica have increased milk production during the dry season. The costs of feeding hay are lower in both countries, although farmers feed a higher amount (kg DM/cow/ day) than silage. Feeding silage or hay to milking cows is profitable in both countries. The income-cost ratio and the net benefit ($/ cow/day) due to feeding these feedstuffs are positive. Farmers with milking cows in Honduras realise a higher income-cost ratio and net benefit due to feeding silage and hay than farmers in Costa Rica. Likewise, beef cows or young livestock supplemented with these feeding alternatives don't loose weight during the dry season. In Honduras as well in Costa Rica, it is profitable to feed silage or hay to beef cows or young livestock. Currently, no silage and a small hay market exist in Honduras. Possibly, these will develop due to an increasing demand for these profitable feedstuffs. In Costa Rica thanks to the efforts of agricultural organisations, a hay market of different qualities is developing

    Coincidence measurement of residues and light particles in the reaction 56Fe+p at 1 GeV per nucleon with SPALADIN

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    The spallation of 56^{56}Fe in collisions with hydrogen at 1 A GeV has been studied in inverse kinematics with the large-aperture setup SPALADIN at GSI. Coincidences of residues with low-center-of-mass kinetic energy light particles and fragments have been measured allowing the decomposition of the total reaction cross-section into the different possible de-excitation channels. Detailed information on the evolution of these de-excitation channels with excitation energy has also been obtained. The comparison of the data with predictions of several de-excitation models coupled to the INCL4 intra-nuclear cascade model shows that only GEMINI can reasonably account for the bulk of collected results, indicating that in a light system with no compression and little angular momentum, multifragmentation might not be necessary to explain the data.Comment: 4 pages, 5 figures, revised version accepted in Phys. Rev. Let

    8-weeks of aerobic training program decreases Malondialdehyde concentration in stressed rats

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    In recent years it has been shown that psychological stress induced by immobilization changes the balance between pro-oxidant and antioxidant factors inducing oxidative damage. Fortunately several studies have reported that regular exercise may reduce oxidative damage. Consequently, the present work was designed to assess the influence of an 8-week moderate intensity swimming training program in psychological stressed rats. To get this goal, sixty 6-8-weeks-old male albino Wistar rats weighing 145-155 g were used in this experimental study. They were divided into three groups: control (lot A; n=20), stressed (lot B; n=20) and stressed & exercised (lot C; n=20). Rats were stressed by placing animals in a 25x7 cm plastic bottle 1 h/day, 5 day/week for 8 weeks. The policy statement of the American College of Sports Medicine on Research with Experimental Animals was followed. Malondialdehyde (MDA) content values in liver homogenates were significantly decreased in stressed & exercised animals (29.4±3.6 vs 21.8±2.7; p\u3c0.001) when compared with stressed rats. It can be concluded that an 8-week moderate intensity training program reduced lipoperoxidation induced by psychological stress

    Ensayos normativos para la caracterización de patologías en pizarras para cubiertas

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    The pathologies formed in slate roofs are mainly due to the presence of potentially unstable minerals (iron sulfides, carbonates and organic matter). These minerals may become altered by the effect of environmental agents, once the slate roof is finished. The pathologies are mainly associated with oxidation and gypsification processes of the cited mineral phases. In this work, the potential pathologies of several Spanish roofing slates are identified, using the tests defined in the European Norms EN 12326:2005, 14147:2004 and 11597:2007.Las patologías que se originan en pizarra para cubiertas son debidas fundamentalmente a la presencia de materiales alterables (sulfuros de hierro, carbonatos y materia orgánica). Estos minerales pueden llegar a alterarse por efecto de los agentes medioambientales, una vez que la pizarra es puesta en obra. Las patologías están principalmente asociadas a procesos de oxidación y yesificación de las citadas fases minerales. En este trabajo se determinan las patologías potenciales de varias pizarras para cubiertas españolas, utilizando los ensayos definidos en las normas UNE-EN 12326:2005, 14147:2004 y 11597:2007

    Analyzing Explosive Volcanic Deposits From Satellite‐Based Radar Backscatter, Volcán de Fuego, 2018

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    Satellite radar backscatter has the potential to provide useful information about the progression of volcanic eruptions when optical, ground-based, or radar phase-based measurements are limited. However, backscatter changes are complex and challenging to interpret: explosive deposits produce different signals depending on pre-existing ground cover, radar parameters and eruption characteristics. We use high temporal- and spatial-resolution backscatter imagery to examine the emplacement and alteration of pyroclastic density currents (PDCs), lahar and ash deposits from the June 2018 eruption of Volcán de Fuego, Guatemala, using observatory reports and rainfall gauge data to ground truth our observations. We use a temporally dense time series of backscatter data to reduce noise and extract deposit areas. We observe backscatter changes in six drainages, the largest deposit was 11.9-km-long that altered an area of 6.3 urn:x-wiley:21699313:media:jgrb55183:jgrb55183-math-0001 and had a thickness of 10.5 urn:x-wiley:21699313:media:jgrb55183:jgrb55183-math-00022 m in the lower sections as estimated from radar shadows. The 3 June eruption also produced backscatter signal over an area of 40 urn:x-wiley:21699313:media:jgrb55183:jgrb55183-math-0003, consistent with reported ashfall. We use transient patterns in backscatter time series to identify nine periods of high lahar activity in a single drainage system between June and October 2018. We find that the characterisation of subtle backscatter signals associated with explosive eruptions are best observed with (1) radiometric terrain calibration, (2) speckle correction, and (3) consideration of pre-existing scattering properties. Our observations demonstrate that SAR backscatter can capture the emplacement and subsequent alteration of a range of explosive deposits, allowing the progression of an explosive eruption to be monitored

    Spallation Residues in the Reaction 56Fe + p at 0.3, 0.5, 0.75, 1.0 and 1.5 A GeV

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    The spallation residues produced in the bombardment of 56}Fe at 1.5, 1.0, 0.75, 0.5 and 0.3 A GeV on a liquid-hydrogen target have been measured using the reverse kinematics technique and the Fragment Separator at GSI (Darmstadt). This technique has permitted the full identification in charge and mass of all isotopes produced with cross-sections larger than 10^{-2} mb down to Z=8. Their individual production cross-sections and recoil velocities at the five energies are presented. Production cross-sections are compared to previously existing data and to empirical parametric formulas, often used in cosmic-ray astrophysics. The experimental data are also extensively compared to different combinations of intra-nuclear cascade and de-excitation models. It is shown that the yields of the lightest isotopes cannot be accounted for by standard evaporation models. The GEMINI model, which includes an asymmetric fission decay mode, gives an overall good agreement with the data. These experimental data can be directly used for the estimation of composition modifications and damages in materials containing iron in spallation sources. They are also useful for improving high precision cosmic-ray measurements.Comment: Submited to Phys. Rev. C (10/2006

    Fisiología reproductiva del pez Betta splendens en condiciones de laboratorio, Piedemonte Andino Amazónico (Colombia)

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    Las estrategias reproductivas (cortejo, fecundación, fertilización e incubación) del pez Betta splendens, así como su desarrollo embrionario (cigoto, mórula, blástula, gástrula, organogénesis y eclosión) fueron observados y registrados en 100 huevos previamente fecundados bajo condiciones de laboratorio (temperatura 27,8ºC, pH 6,8) en la Universidad de la Amazonia (Florencia, Caquetá, Colombia), con el fin de obtener información que genere ventajas para la producción y comercialización de esta especie. Se utilizó el programa Toup View versión 2.1 con el cual se midieron las estructuras morfológicas de 32 ovocitos cada 5 minutos hasta la organogénesis y después cada cuatro horas hasta la eclosión. Se obtuvo una tasa de fertilidad de los desoves de 83±2,0%. El tiempo transcurrido desde la fecundación hasta la eclosión fue de 36,13 h. El tamaño del disco germinal fue de 529,39 μm, el radio de 5,64 μm y el saco vitelino de 679,43 μm. Después de la fecundación, el huevo sufrió una serie de cambios muy rápidos (±36 h) del desarrollo embrionario, incluyendo la segmentación (40 min), ciclaje (50 min), gastrulación (55 min), segmentación y organogénesis (16 min), morfogénesis (21 h), eclosión y estado larvario (13 h). Se concluye que el desarrollo embrionario de B. splendens es más corto (36.13 h) que el de otros peces teleósteos, dato que servirá como información base para estudios encauzados a la reproducción de esta especie con fines comerciales.
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