867 resultados para Crystal growth-theory and techniques
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
Non-linear mathematical functions proposed by Brody, Gompertz, Richards, Bertalanffy and Verhulst were compared in several buffalo production systems in Colombia. Herds were located in three provinces: Antioquia, Caldas, and Cordoba. Growth was better described by the curves proposed by Brody and Gompertz. Using the datasets from herds from Caldas, heritabilities for traits such as weaning weight (WW), weight and maturity at one year of age (WY and MY, respectively), age at 50% and 75% of maturity (A50% and A75%, respectively), adult weight (beta(0)), and other characteristics, were also estimated. Direct and maternal heritabilities for WW were 0.19 and 0.12, respectively. Direct heritabilities for WY, MY, A50%, A75% and beta(0) were 0.39, 0.15, 0.09, 0.20 and 0.09, respectively. The genetic correlation for beta(0) and WY was -0.47, indicating that selection for heavy weight at one year of age will lead to lower weight at adult age. These data suggest that selection based on maturity traits can generate changes in characteristics of economic importance in beef-type buffalo farms.
Resumo:
We tested the effects of monochromatic light on the specific growth rate (SGR), feed intake and feed efficiency (FE) of juvenile pikeperch, Sander lucioperca (L.). Pikeperch were reared individually for 42 days in aquaria covered with blue, green, yellow or red gelatin filters or white paper (control; n=5). Linear regression analysis indicated a significant positive effect of longer wavelengths of light on the condition factor (CF), FE and SGR. The final weight, SGR and CF were significantly higher in fish reared under red than under white light, and FE was better under green, yellow and red light than under white light (Dunnett's post hoc test, P < 0.05) while blue was comparable to white light in terms of the measured parameters. After the growth trial, the spectral sensitivity of photoreceptor cells in the retina was tested using microspectrophotometry, which revealed the presence of rods with lambda(max) at ca. 530 nm and two cone classes, absorbing maximally at ca. 535 and 603 nm, all containing a porphyropsin-based pigment. These results suggest that the presence of mid and long wavelength-sensitive cones enhances visual sensitivity under mid-wavelength and long-wavelength environments, and thus supports the finding that longer wavelengths of incoming light can improve FE and SGR of the cultivated pikeperch.
Resumo:
Angelonia salicariifolia is an herbaceous perennial native to Brazil with ornamental potential as garden plant, cut-flower and potted plant. It has blue flowers 1.0 to 1.4 cm long, in 10-30 cm long terminal racemes. In previous studies seeds of A. salicariifolia showed a positive photoblastic behavior under constant temperatures of 10, 15, 20, 25, 30 and 35 degrees C. The present study evaluated the effects of growth regulators (100, 200, 300, 400, 500 mg L-1 of gibberellic acid and 2.25, 11.3, 22.5 mg L-1 of 6-benzylamino-purine) and potassium nitrate (0.2 and 1.0 %) on promoting its seed germination. The experiment was conducted in a completely randomized design with six replications of 25 seeds, for each treatment. Seeds from dehiscent capsules were sown on one layer of filter paper and moistened with growth regulators or KNO3 solutions. Germination was carried out at 25 degrees C +/- 1 degrees C, under continuous light or darkness. Germination (protusion of the radicle) was observed daily for 20 days. In the dark, only gibberellic acid promoted seed germination. The percentage of germination and the speed of germination index at 400 mg L-1 (47.3%; 0.86) and 500 mg L-1 (52.0%; 0.95) were significantly higher compared to 100 mg L-1 (27.8%; 0.38) and 200 mg L-1 (32.3%; 0.49). The mean germination time at 500 mg L-1 (10.0 days) was significantly smaller compared to 100 mg L-1 (11.9 days) and 200 mg L-1 (11.5 days). Under light, treatments did not differ among each other or from the control, except for 22.5 mg L-1 of 6-benzylamino-purine and potassium nitrate (1.0%), which decreased the percentage of germination and the speed of germination index compared to control. The application of growth regulators or potassium nitrate under light condition is not necessary, since these treatments did not improve germination percentage or the speed of germination index.
Resumo:
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Resumo:
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Resumo:
Seven male broiler strains (Arbor Acres, Avian Farms, Cobb-500, Hubbard-Peterson, ISA, Naked Neck, and Ross) were compared for their growth rate, feed efficiency, and mortality due to sudden death and ascites. In addition, weekly plasma levels of thyroid hormones [3,3′,5-triiodothyronine (T3) thyroxine (T4), T3: T4 ratio, growth hormone (GH), and insulin-like growth factor-I (IGF-I)] were determined. The highly productive, commercial strains were very similar in their endocrine profiles but differed markedly from the Naked Neck chickens. Naked Neck chickens were characterized by higher plasma T3 and lower T4 levels at similar ages as well as when compared on the same body weight basis. The present findings support the hypothesis that the slightly hypothyroid state of high productive broilers renders them more sensitive to metabolic disorders. Naked Neck chickens also had higher plasma GH levels than those of their age-matched commercial broilers. The coefficient of variation for GH was highest for Naked Neck chickens, which is indicative for an amplified GH burst amplitude. It may be stated that changes in plasma thyroid hormone concentration in indirect response to selection for low feed conversion and fast growth may be causatively linked to susceptibility for metabolic disturbances such as sudden death syndrome and ascites.
Resumo:
In order to evaluate growth characteristics, adaptability, biomass production, nutrient recycling, nutrient distribution and the ability to regenerate degraded land, a trial using four multipurpose tree species (Leucaena leucocephala, Leucaena diversifolia, Acacia melanoxylon and Mimosa scabrella) was undertaken over two years in a distrophic red yellow latosol (oxisol) following a randomized block experimental design with four replications. At the age of two years, A. melanoxylon and L. diversifolia were the tallest species (5.25 and 4.97 m, respectively) and A. melanoxylon and M. scabrella had the largest diameters at 20 cm from tree base. Mimosa scabrella and A. melanoxylon had the highest dry matter production and quantity of nutrients in the above ground biomass. In all species, the highest nutrient contents were found in the leaves, followed by branches and stems. From all species, the highest Nutrient Utilization Efficiency Indexes were obtained for sulphur, phosphorous, and magnesium; L. diversifolia was the most efficient for nitrogen, potassium, calcium, sulphur, and manganese, while A. melanoxylon was the most efficient for phosphorus, magnesium, boron, iron, and zinc. Litter production levels over a three month period were as follows: M. scabrella > A. melanoxylon > L. diversifolia > L. leucocephala. Litter nutrient content was higher in M. scabrella than in the other species.
Resumo:
Some properties of the higher grading integrable generalizations of the conformal affine Toda systems are studied. The fields associated to the non-zero grade generators are Dirac spinors. The effective action is written in terms of the Wess-Zumino-Novikov-Witten (WZNW) action associated to an affine Lie algebra, and an off-critical theory is obtained as the result of the spontaneous breakdown of the conformal symmetry. Moreover, the off-critical theory presents a remarkable equivalence between the Noether and topological currents of the model. Related to the off-critical model we define a real and local lagrangian provided some reality conditions are imposed on the fields of the model. This real action model is expected to describe the soliton sector of the original model, and turns out to be the master action from which we uncover the weak-strong phases described by (generalized) massive Thirring and sine-Gordon type models, respectively. The case of any (untwisted) affine Lie algebra furnished with the principal gradation is studied in some detail. The example of s^l(n) (n = 2, 3) is presented explicitly. © SISSA/ISAS 2003.
Resumo:
Analysis of variance and covariance was preformed on growth traits (stem girth, bark thickness, total height gain and rubber yield) of 22 open-pollinated progenies of the rubber tree Hevea brasiliensis from an Asian Hevea collection introduced to Agronomic Institute (Instituto Agronômico, Campinas, São Paulo, Brazil; IAC) in 1952. This progeny trial was replicated at three sites in São Paulo state and it was found that at three years from sowing there was statistically significant variation for girth, bark thickness, height and rubber yield. An individual test sites, values of individual plant heritability for girth ranged from ĥ i 2 = 0.36 to ĥ i 2 = 0.89 whereas values for heritability for progeny means ranged from ĥ i 2 = 0.77 to ĥ i 2 = 0.87. These moderate and high heritabilities suggest that a combination of progeny and within-progeny selection would be effective at increasing girth in this population at individual sites. Across sites, values of individual-plant heritability for girth ranged from ĥ i 2 = 0.36 to ĥ i 2 = 0.47, whereas values for heritability of progeny means girth ranged from ĥ x̄ 2 = 0.77 to ĥ x̄ 2 = 0.87. There were high positive genetic correlations between increased girth and bark thickness suggesting that breeding aimed at increasing girth would also increase bark thickness and possibly height. Copyright by the Brazilian Society of Genetics.
Resumo:
Includes bibliography