905 resultados para Size effects
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Considering the different potential benefits of divergent fiber ingredients, the effect of 3 fiber sources on energy and macronutrient digestibility, fermentation product formation, postprandial metabolite responses, and colon histology of overweight cats (Felis catus) fed kibble diets was compared. Twenty-four healthy adult cats were assigned in a complete randomized block design to 2 groups of 12 animals, and 3 animals from each group were fed 1 of 4 of the following kibble diets: control (CO; 11.5% dietary fiber), beet pulp (BP; 26% dietary fiber), wheat bran (WB; 24% dietary fiber), and sugarcane fiber (SF; 28% dietary fiber). Digestibility was measured by the total collection of feces. After 16 d of diet adaptation and an overnight period without food, blood glucose, cholesterol, and triglyceride postprandial responses were evaluated for 16 h after continued exposure to food. on d 20, colon biopsies of the cats were collected under general anesthesia. Fiber addition reduced food energy and nutrient digestibility. of all the fiber sources, SF had the least dietary fiber digestibility (P < 0.05), causing the largest reduction of dietary energy digestibility (P < 0.05). The greater fermentability of BP resulted in reduced fecal DM and pH, greater fecal production [g/(cat x d); as-is], and greater fecal concentration of acetate, propionate, and lactate (P < 0.05). For most fecal variables, WB was intermediate between BP and SF, and SF was similar to the control diet except for an increased fecal DM and firmer feces production for the SF diet (P < 0.05). Postprandial evaluations indicated reduced mean glucose concentration and area under the glucose curve in cats fed the SF diet (P < 0.05). Colon mucosa thickness, crypt area, lamina propria area, goblet cell area, crypt mean size, and crypt in bifurcation did not vary among the diets. According to the fiber solubility and fermentation rates, fiber sources can induce different physiological responses in cats, reduce energy digestibility, and favor glucose metabolism (SF), or improve gut health (BP).
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Maternal antibody (MatAb) transfer is important for early chicken survivability. Diet composition and the amount of feed given to breeder pullets during rearing may affect the development of immunity and the transfer of MatAb to progeny, and could affect progeny performance and resistance to disease. The effects of broiler breeder nutrition and feeding management practices were evaluated for the transfer of MatAb to progeny and for spleen and bursa development at hatching in 2 genetic strains (A and B). In this experiment, the levels of MatAb against Newcastle disease virus were assessed by enzyme-linked immunosorbent assays in serum samples taken of pedigreed chicken progeny from hatching to 13 d of age. Chickens were fed corn-and wheat-based diets, as were their parents. The breeder feeding program and diet type altered the Newcastle disease virus MatAb found in progeny at hatching and affected how long these antibodies were maintained in circulation. Bursal follicle size at hatching was influenced by an interaction among all factors evaluated. Percentage of white pulp in the spleen was affected mainly by genetic strain and diet type, but responses varied according to the breeder feeding program. It was concluded that breeder feeding programs influence MatAb transfer and half-life, and may also affect the early development of lymphoid tissues.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Channel catfish, Ictalurus punctatus, fingerlings (mean length: 4.0±0.5 cm) were stocked into sixteen 16-m2 tanks with cement walls and earth bottoms. Four stocking densities were used: 10, 15, 20, and 25 fish/m2. Fish were fed a prepared diet containing 36% protein according to a fish size/water temperature-dependant chart for 120 days. Fish were stocked on January 20, 1992. Average water temperature varied from 19.7°C to 28.5°C. Final mean values of individual fish length and weight were significantly higher (P < 0.05) for the density of 10 fish/m2 and averaged 19.4±2.6 cm and 70.0±16.9 g, respectively. Food conversion ratio was significantly higher (P < 0.05) for fish stocked at rate of 25 fish/m2. Survival rates averaged 91.4%, with no significant differences (P > 0.05) found among treatments. These results demonstrate the viability of channel catfish fingerling growth in southern Brazil.
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Macroecology evaluates the partitioning of physical space and resources among organisms through correlation among ecological variables, such as geographical range size and shape, body size, and population density, measured at large geographical and taxonomic scales. In this article, we analyzed the spatial patterns in worker body size and geographic range size for the 27 described species of honey ants, genus Myrmecocystus Wesmael, in the United States and Mexico, and especially the relationship between these 2 variables after statistically removing their spatial patterns. The 2 variables are correlated, but also displayed significant spatial patterns, as detected by trend surface and spatial autocorrelation analyses. After removing these spatial effects, worker body size and geographic range size were still positively correlated. The relationship, therefore, is not a consequence of spatial effects and it does follow Brown's model, which predicts that the geographic range size will have a positive slope on body size. In this model, the lower population densities caused by foraging activities and local territorial competition are associated with a large geographic range, avoiding stochastic extinction. Although this constraint in local population density does not necessarily hold for small organisms such as insects that could achieve high densities even in very small areas and patchy habitats, it may hold for social insects, especially ants, because of the local competition among colonies.
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The effect of cyclosporine on adriamycin nephropathy was studied over both short (6 weeks) and long (26 weeks) periods. In the short-term study, cyclosporine was introduced 2 weeks after nephritis induction and in the long-term study, 14 weeks after the first adriamycin injection. The animals with adriamycin nephropathy treated with cyclosporine, studied for 6 weeks, developed proteinuria with increased renal size and glomerular area. The nephrotic animals treated with cyclosporine showed less proteinuria than the nephrotic control animals. There were no differences in glomerular area, creatinine clearance or serum creatinine and kidney weight between the treated nephrotic group and the health control group. The nephrotic animals, studied for the longer period, developed intense proteinuria, decreased creatinine clearance, glomerular necrosis and sclerosis, severe tubulointerstitial nephritis, increased hydroxyproline concentration and tubulointerstitial area. No difference was observed between the nephrotic animals treated with cyclosporine and those not treated. In conclusion, Cyclosporine A reduced proteinuria, glomerular hypertrophy and kidney weight in rats with short-term nephropathy but had no effect on the established nephropathy.
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We study signals for the production of superparticles at the Fermilab Tevatron in supergravity scenarios based on the grand unified group SO(10). The breaking of this group introduces extra contributions to the masses of all scalars, described by a single new parameter. We find that varying this parameter can considerably change the size of various expected signals studied in the literature, with different numbers of jets and/or charged leptons in the final state. The ratios of these signals can thus serve as a diagnostic to detect or constrain deviations from the much-studied scenario where all scalar masses are universal at the GUT scale. Moreover, under favorable circumstances some of these signals, and/or new signals involving hard b jets, should be observable at the next run of the Fermilab Tevatron collider even if the average scalar mass lies well above the gluino mass. ©2000 The American Physical Society.
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Sixty adult tats (Rattus norvegicus albinus) of the same age (3 months) and with a mean body weight of 228 g were divided into two experimental groups. The control group received solid diet (Purina rat chow) and tap water ad libitum. The other (alcoholic group), received the same solid diet and was allowed to drink only sugar cane brandy dissolved in 30° Gay Lussac (v/v). At the end of periods of 90, 180 and 270 days of treatment, the animals were anaesthetized with ethyl ether during estrus, weighed and sacrificed. The final mean body weights were similar in the control and alcoholic groups. The results showed intense atrophy on the lining epithelium of the endometrium of uterine horns in the alcoholic group. Important ultrastructural epithelial alterations were also observed in the female alcoholic group, such as: intense lipid droplet accumulation, increased rough endoplasmic reticulum cisternae and mitochondrial size and presence of intraepithelial neutrophils. The secretory activity of these rats was reduced. Therefore, we concluded that alcohol acts as a toxin on the epithelial layer of the rat endometrium.
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Excluded volume effects are incorporated in the quark-meson coupling model to take into account in a phenomenological way the hard-core repulsion of the nuclear force. The formalism employed is thermodynamically consistent and does not violate causality. The effects of the excluded volume on in-medium nucleon properties and the nuclear matter equation of state are investigated as a function of the size of the hard core. It is found that in-medium nucleon properties are not altered significantly by the excluded volume, even for large hard-core radii, and the equation of state becomes stiffer as the size of the hard core increases.
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Background: Lung deposition of intravenous cephalosporins is low. The lung deposition of equivalent doses of ceftazidime administered either intravenously or by ultrasonic nebulization using either nitrogen-oxygen or helium-oxygen as the carrying gas of the aerosol was compared in ventilated piglets with and without experimental bronchopneumonia. Methods: Five piglets with noninfected lungs and 5 piglets with Pseudomonas aeruginosa experimental bronchopneumonia received 33 mg/kg ceftazidime intravenously. Ten piglets with noninfected lungs and 10 others with experimental P. aeruginosa bronchopneumonia received 50 mg/kg ceftazidime by ultrasonic nebulization. In each group, the ventilator was operated in half of the animals with a 65%/35% helium-oxygen or nitrogen-oxygen mixture. Animals were killed, and multiple lung specimens were sampled for measuring ceftazidime lung tissue concentrations by high-performance liquid chromatography. Results: As compared with intravenous administration, nebulization of ceftazidime significantly increased lung tissue concentrations (17 ± 13 vs. 383 ± 84 μg/g in noninfected piglets and 10 ± 3 vs. 129 ± 108 μg/g in piglets with experimental bronchopneumonia; P < 0.001). The use of a 65%/35% helium-oxygen mixture induced a 33% additional increase in lung tissue concentrations in noninfected piglets (576 ± 141 μg/g; P < 0.001) and no significant change in infected piglets (111 ± 104 μg/g). Conclusion: Nebulization of ceftazidime induced a 5- to 30-fold increase in lung tissue concentrations as compared with intravenous administration. Using a helium-oxygen mixture as the carrying gas of the aerosol induced a substantial additional increase in lung deposition in noninfected piglets but not in piglets with experimental bronchopneumonia. © 2005 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.
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The microstructure and dielectric properties of Nb-Mn or Sb-Mn codoped BaTiO3 compositions were investigated. Starting ceramics powders were prepared by Pechini method. The composites were sintered at 1310°C and 1330°C in an air atmosphere for two hours. The microstructure and compositional investigations were done with SEM equipped with EDS. Two distinguish microstructure regions are observed in Nb/0.05Mn doped BaTiO 3 ceramics sintered at low temperature. The first, large one, with grain sizes from 5-40 μm and the second region with small grain sizes from 1 to 5 μm. Sintering at higher temperature, independent of Mn content, enables to achieve a uniform microstructure with grains less than 6 μm. In Sb/Mn doped ceramics, for both sintering temperatures, bimodal microstructures with fine grained matrix and grains up to 10 μm is formed. The highest value of permittivity at room temperature and the greatest change of permittivity in function of temperature are observed in Nb/0.01Mn doped ceramics compared to the same ones in Sb/Mn doped ceramics. The greatest shift of Curie temperature towards lower temperature has been noticed in Sb/Mn BaTiO3 ceramics compared to others samples. In all investigated samples the dielectric loss after initially large values at low frequency maintains a constant value for f>3 kHz.
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An experiment was carried out in order to investigate the behaviors of laying hens due to the environmental factors of: density inside of the cage, aviary type, breed, and age. The experiment was configured as a factorial 4x2x2x2 study, with treatments being four different ages, two different breeds, two different cage densities, and two different aviaries. The birds' behaviors were recorded using video cameras installed in the cages, using samples of 15 minutes recorded from 12 PM to 4 PM. The observed behaviors, frequency and duration of behaviors (measured in seconds) were identified and noted related to each bird. The study was initiated in March 2007, during four non-consecutive weeks. The observed behaviors were: opening wings, stretching, threatening, ruffling feathers, drinking water, aggressive pecking, eating, running, lying down, stretching head out of the cage, preening, mounting, prostrating, and doing nothing (inactivity). Due to the non-normality of the data recorded, the Kruskal-Wallis statistical test of the MINITAB Statistical Software® was used to compare the medians of the variables. For breed factor, only the durations of the eating presented significant differences (p-value< 0.05). For cage density, there was a significant median difference (p-value< 0.05) for almost all behaviors observed. The average length of time of behaviors was higher for the lowest cage density. However, the frequency of behaviors was lmerfor the lowest cage density. The frequency of the behaviors to preen feathers, to lie down, to drink water and to stretch the head were higher in the aviary, where the groups of birds were smaller. The observed behaviors were particularly affected by experimental factors cage density, and aviary type, which directly affects the available space for each bird.
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To evaluate the effects of distinct management of the matrix in which forest fragments are found upon plant populations thriving in forest remnants in south Brazil, we assessed the conservation status of populations of four woody species (Campomanesia rhombea, Diospyros incontans, Myrciaria cuspidata and Sebastiania commersoniana) through analyses of size structure. Analyzes were carried out at two scales. At a local scale, we consider populations in fragments surrounded by pastures or eucalypts forest plantations, and at a regional scale we also consider larger forest tracts taken as reference areas (Rio Grande do Sul Forest Inventory databank). Population size structures were summarized using the symmetry of height distributions. Small individual size classes prevailed at the local scale in fragments surrounded by eucalypts plantations, whereas in areas exposed to cattle ranching, populations of the same species consistently lack small individuals. At the regional scale, populations in fragments surrounded by pastures presented greater skewness (prevalence of small plants) than populations in reference areas, while populations surrounded by eucalypts plantations presented intermediate skewness. These results reinforce the notion that plantations have a higher conservation value for forest ecosystems than other commercial land uses, like cattle ranching. © 2010 Springer Science+Business Media B.V.