87 resultados para Least squares learning


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Objetivou-se, no presente estudo, avaliar a produção de leite de caprinos leiteiros da região sudeste do Brasil, com intuito de verificar os fatores de meio e estimar os parâmetros genéticos pelo método dos mínimos quadrados (MMQ). Os controles de 1336 lactações foram inicialmente ajustados pela função multifásica (difásica) e calculou-se a produção de leite total (PLT). Os dados foram provenientes de sete propriedades e três raças (Parda Alpina, Saanen e Toggenburg). A média e o erro-padrão da PLT estimados pelo MMQ foram de 635,31 ±39,75 kg. A interação ano x estação do parto influenciou a PLT. em um dos anos estudados, a PLT foi menor para as cabras paridas no final da estação. Nas três estações de parto, observou-se comportamento quadrático da PLT, em função dos anos de parto. Para as três estações, a PLT aumentou de 1986 até meados de 1990, decrescendo em seguida. A idade de máxima PLT foi observada aos 46,65 meses. Das três raças estudadas, observou-se que as raças Parda Alpina e Saanen apresentaram alternância de superioridade na PLT em algumas fazendas, porém maiores que a Toggenburg. Os coeficientes de herdabilidade e repetibilidade da PLT estimados pelo MMQ foram de 0,296 ± 0,079 e 0,277 ± 0,033, respectivamente. Estes resultados revelam baixa confiabilidade em poucas observações dessas características ou na inconsistência das estimativas da função multifásica. Como a PLT é uma característica limitada ao sexo, sugere-se o teste de progênie como método de seleção mais eficiente para os reprodutores e uso de inseminação artificial como processo de disseminação do material genético selecionado.

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Two experiments were designed to evaluate strategies to increase fertility of Bos indicus postpubertal heifers and nonlactating cows submitted to a fixed-time artificial insemination (TAI) protocol consisting of an intravaginal device containing 1.9 g of progesterone (CIDR) insertion + estradiol benzoate on Day 0, CIDR withdrawal + estradiol cypionate on Day 9, and TAI on Day 11. In Experiment 1, heifers (n = 1153) received a new or an 18-d previously used CIDR and, on Day 9, prostaglandin F(2 alpha) (PGF(2 alpha)) + 0, 200, or 300 IU equine chorionic gonadotropin (eCG). Heifers treated with a new CIDR had greater (least squares means +/- SEM) serum concentration of progesterone on Day 9 (3.06 +/- 0.09 ng/mL vs. 2.53 +/- 0.09 ng/mL; P < 0.05) and a smaller follicle at TAI (11.61 +/- 0.11 nim vs. 12.05 +/- 0.12 mm; P < 0.05). Heifers with smaller follicles at TAI had lesser serum progesterone, concentrations on Day 18 and reduced rates of ovulation, conception, and pregnancy (P < 0.05). Treatment with eCG improved (P < 0.05) follicle diameter at TAI (11.50 +/- 0.10 mm, 11.90 +/- 0.11 mm, and 12.00 +/- 0.10 mm, for 0, 100, and 200 IU, respectively), serum progesterone concentration on Day 18 (2.77 +/- 0.11 ng/mL, 3.81 +/- 0.11 ng/mL, and 4.87 +/- 0.11 ng/mL), and rates of ovulation (83.8%, 88.5%, and 94.3%) and pregnancy (41.3%, 47.0%, and 46.7%). In Experiment 2, nonlactating Nelore cows (n = 702) received PGF(2 alpha) treatment on Days 7 or 9 and, on Day 9, 0 or 300 IU cCG. Cows receiving PGF(2 alpha) on Day 7 had lesser serum progesterone concentrations on Day 9 (3.05 +/- 0.21 ng/mL vs. 4.58 +/- 0.21 ng/mL; P < 0.05), a larger follicle at TAI (11.54 +/- 0.21 mm vs. 10.84 +/- 0.21 mm; P < 0.05), and improved (P < 0.05) rates of ovulation (85.4% vs. 77.0%), conception (60.9% vs. 47.2%), and pregnancy (52.0% vs. 36.4%). Treatment with eCG improved (P < 0.05) serum progesterone concentration on Day 18 (3.24 +/- 0.14 ng/mL vs. 4.55 +/- 0.14 ng/mL) and the rates of ovulation (72.4% vs. 90.0%) and pregnancy (37.5% vs. 50.8%). In conclusion, giving PGF(2 alpha) earlier in the protocol in nonlactating cows and eCG treatment in postpubertal heifers and nonlactating cows improved fertility in response to a TAI (progesterone + estradiol) protocol. (C) 2009 Elsevier B.V. All rights reserved.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Several Brazilian commercial gasoline physicochemical parameters, such as relative density, distillation curve (temperatures related to 10%, 50% and 90% of distilled volume, final boiling point and residue), octane numbers (motor and research octane number and anti-knock index), hydrocarbon compositions (olefins, aromatics and saturates) and anhydrous ethanol and benzene content was predicted from chromatographic profiles obtained by flame ionization detection (GC-FID) and using partial least square regression (PLS). GC-FID is a technique intensively used for fuel quality control due to its convenience, speed, accuracy and simplicity and its profiles are much easier to interpret and understand than results produced by other techniques. Another advantage is that it permits association with multivariate methods of analysis, such as PLS. The chromatogram profiles were recorded and used to deploy PLS models for each property. The standard error of prediction (SEP) has been the main parameter considered to select the "best model". Most of GC-FID-PLS results, when compared to those obtained by the Brazilian Government Petroleum, Natural Gas and Biofuels Agency - ANP Regulation 309 specification methods, were very good. In general, all PLS models developed in these work provide unbiased predictions with lows standard error of prediction and percentage average relative error (below 11.5 and 5.0, respectively). (C) 2007 Elsevier B.V. All rights reserved.

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Este trabalho teve o objetivo de estudar a influência de efeitos não genéticos sobre o peso ao desmame de 105.465 bezerros da raça Nelore, nascidos em oito diferentes regiões brasileiras, no período de 1978 a 1994. A análise estatística foi realizada utilizando-se o método dos quadrados mínimos, procedimento GLM (SAS, 1996), com um modelo estatístico contendo como fontes de variação os efeitos fixos de sexo, mês e ano de nascimento do bezerro, região, fazenda dentro de região, grupo de idade da vaca e, como efeitos aleatórios, touro e o erro. Todas as fontes de variação do modelo foram significativas (P<0,0001). A importância desses efeitos não genéticos sobre o peso aos 205 dias de idade de bezerros da raça Nelore evidenciam a necessidade de se fazer ajustes para os mesmos, visto que estes influenciaram sobre a característica estudada.

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Conselho Nacional do Desenvolvimento Científico e Tecnológico (CNPq)

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Este trabalho foi conduzido com o objetivo de avaliar o efeito de fatores de meio sobre a infestação de bovinos Caracu pelo carrapato Boophilus microplus (Canestrini, 1887) e estimar parâmetros genéticos do grau de infestação por esse ectoparasita. Foram realizadas contagens em fêmeas de dois rebanhos, nas quatro estações, por dois anos consecutivos (setembro/1998 a julho/2000). Contou-se o número de carrapatos (NC) em um dos lados do animal e atribuiu-se escore visual (EC) de acordo com a quantidade de carrapatos no animal. Foram feitas de uma a oito avaliações, totalizando-se 4.079 e 3.994 observações de NC e EC, respectivamente, em 718 animais. Os dados foram analisados pelo método dos quadrados mínimos com um modelo que incluiu efeitos de rebanho (R), cor do animal (C), R x C, animal dentro de R x C como erro a, ano e estação da avaliação, espessura de pelame e idade do animal como covariável. As estimativas dos componentes de variância foram obtidas pelo método da máxima verossimilhança restrita livre de derivadas, utilizando-se um modelo que incluiu os efeitos fixos de grupo de contemporâneos (fazenda-ano-época), espessura do pelame e idade do animal como covariável e os efeitos aleatórios aditivos diretos e de ambiente permanente. Antes das análises, a variável NC foi transformada para log10 (n + 1) e EC para (x + 0,5)½, em que n é o número de carrapatos contados no animal e x, o escore (0 a 4). A incidência de carrapatos foi maior no verão e, quanto maior a espessura do pelame, maior o nível de infestação. As estimativas de herdabilidade e repetibilidade foram, respectivamente, 0,22 e 0,29 para NC e 0,15 e 0,21 para EC; a correlação genética entre NC e EC foi igual a 1,00. Os resultados sugerem que é possível obter progresso genético para resistência a carrapato pela seleção.

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An improved meshless method is presented with an emphasis on the detailed description of this new computational technique and its numerical implementations by investigating the usefulness of a commonly neglected parameter in this paper. Two approaches to enforce essential boundary conditions are also thoroughly investigated. Numerical tests on a mathematical function is carried out as a means of validating the proposed method. It will be seen that the proposed method is more robust than the conventional ones. Applications in solving electromagnetic problems are also presented.

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For data obtained from horizontal soil column experiments, the determination of soil-water transport characteristics and functions would be aided by a single-form equation capable of objectively describing water content theta vs. time t at given position x(f). Our study was conducted to evaluate two such possible equations, one having the form of the Weibull frequency distribution, and the other being called a bipower form. Each equation contained three parameters, and was fitted by nonlinear least squares to the experimental data from three separate columns of a single soil. Across the theta range containing the measured data points obtained by gamma-ray attenuation, the two equations were in close agreement. The resulting family of theta(x(f),t) transients, as obtained from either equation, enabled the evaluation of exponent n in the t(n) dependence of the positional advance of a given theta. Not only was n found to be <0.5 at low theta values, but it also increased with theta and tended toward 0.5 as theta approached its sated (near-saturated) value. Some quantitative uncertainty in n(theta) does arise due to the reduced number of data points available at the higher water contents. Without claiming non-Boltzmann behavior (n < 0.5) as necessarily representative of all soils, we nonetheless consider n(theta) to be worthy of further study for evaluating its significance and implications.

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Effects of sire breed-grazing system and environmental factors on the first activities of high grade Nellore and crossbred Canchim x Nellore, Angus x Nellore, and Simmental x Nellore calves raised in intensive production systems and high grade Nellore calves raised in an extensive production system, after birth, were studied. During 2 years, 185 calves were observed from birth until the end of first suckling, and the following variables were estimated: duration of maternal attention (cow to calf) during the first 15 min after calving, latency to first attempt to stand up, latency to stand up, latency to first suckling, duration of first suckling and the interval from standing to suckling. Data were analyzed by least squares methods, with models that included fixed effects of year and time of the year of birth (March-April (early autumn) and May-June (late autumn)), sire breed-grazing system (Sy), sex of calf (Se), category of cow (primiparous and pluriparous), time of birth, Sy x Se, year x Sy and year x time of the year interactions and the covariates weight of calf, rainfall, air temperature and relative humidity in the day of birth. Calves born from 6:00 to 8:00 h presented the longest latencies to first stand up (40.3 +/- 5.1 min) and the shortest occur from 14:00 to 16:00 h (15.8 +/- 2.7 min) (P < 0.01). Primiparous cows provided longer attention toward the calf in the first 15 min after birth than pluriparous cows (13.0 +/- 0.7 min versus 11.1 +/- 0.5 min; P < 0.05). This attention was also shorter in earlier autumn (11.0 +/- 0.5 min) and longer in late autumn (13.1 +/- 0.8 min) (P < 0.05). Relative to sire breed-grazing system, Nellore calves raised intensively did take longer to stand and to suckle after birth as compared to crossbred calves also raised intensively (P < 0.01). However, grazing system did not affect (P > 0.05) any behaviour variable studied. As regard to sex differences, female calves did take less (P < 0.01) time to suckle after standing than male calves. Results showed that even purebred or crossbred Bos indicus calves in subtropical environmental need extra care when born on rainy days, especially during the first hours of the day. (C) 2006 Elsevier B.V. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The crystal structure of benzoyl-histidine monohydrate (BYLH hereafter), C-13H-12N-3O-3. H2O was determined from three dimensional data of 3012 independent reflections measured on a Enraf-Nonius (CAD4) single crystal diffractometer. The compound crystallizes in the orthorhombic space group P2(1)2(1)2(1) with cell dimensions alpha = 7.102(1) angstrom, b = 13.783(3) angstrom, c = 14.160(4) angstrom, V = 1385.92 angstrom-3, F.W. = 277.28, F(000) = 584 Q(calc) = 1.32 g cm-3 and Z = 4.The structure was solved with direct methods. All positional and anisotropic thermal parameters were refined by full-matrix least-squares calculations. The final reliability factor was R = 0.040, while the weighted one was Rw = 0.034. The H atoms found in the difference Fourier map were refined isotropically.The compound consists of a histidine molecule bound to a benzoyl group. There is also a cocrystallized water molecule stabilized through a hydrogen bridge.The 5-membered ring of the histidine has its tautomeric form, after the transfer of the H atom from the N(delta) to the N(epsilon) atom of the ring. There is an sp2 conformation around C6 while the conformation around C3 is that of sp3. The histidine ring forms with the benzene ring a dihedral angle of 109.8(1)-degree.All angle values and bond distances agree very well with the expected values in the literature.

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Cassava starch has been shown to make transparent and colorless flexible films without any previous chemical treatment. The functional properties of edible films are influenced by starch properties, including chain conformation, molecular bonding, crystallinity, and water content. Fourier-transform infrared (FTIR) spectroscopy in combination with attenuated total reflectance (ATR) has been applied for the elucidation of the structure and conformation of carbohydrates. This technique associated with chemometric data processing could indicate the relationship between the structural parameters and the functional properties of cassava starch-based edible films. Successful prediction of the functional properties values of the starch-based films was achieved by partial least squares regression data. The results showed that presence of the hydroxyl group on carbon 6 of the cyclic part of glucose is directly correlated with the functional properties of cassava starch films.

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The element-free Galerkin method (EFGM) is a very attractive technique for solutions of partial differential equations, since it makes use of nodal point configurations which do not require a mesh. Therefore, it differs from FEM-like approaches by avoiding the need of meshing, a very demanding task for complicated geometry problems. However, the imposition of boundary conditions is not straightforward, since the EFGM is based on moving-least-squares (MLS) approximations which are not necessarily interpolants. This feature requires, for instance, the introduction of modified functionals with additional unknown parameters such as Lagrange multipliers, a serious drawback which leads to poor conditionings of the matrix equations. In this paper, an interpolatory formulation for MLS approximants is presented: it allows the direct introduction of boundary conditions, reducing the processing time and improving the condition numbers. The formulation is applied to the study of two-dimensional magnetohydrodynamic flow problems, and the computed results confirm the accuracy and correctness of the proposed formulation. (C) 2002 Elsevier B.V. All rights reserved.