985 resultados para logistic model


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Pós-graduação em Biometria - IBB

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

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Pós-graduação em Odontologia Preventiva e Social - FOA

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The knowledge of how animals deposited chemical components as water, protein, fat and ash in the carcass is importance for the formulation of a balanced diet, allowing maximum performance with a low environmental impact. So, the study was carried out to evaluate the influence of different tilapia strains (Chitralada, Commercial, Red and Universidade Federal de Lavras [UFLA]) on the deposition of bodily chemical components in the carcass. The bodily components analyzed were water, protein, fat and ash. For the determination of the bodily chemical deposition curves by age, the exponential, Brody, logistic, Gompertz and von Bertalanffy models were adjusted. The Commercial and UFLA strains deposited water at a faster speed (P<0.05) compared with the remaining strains. As for protein, the Red strain had a lower estimated maturity weight (49.37 g), and was more precocious (202 days) with regard to maximum deposition in comparison to the other strains (Chitralada, UFLA and Commercial) in which there was an estimated maturity weight of 231.5 g and maximum depositionfor 337 days. There were no differences (P>0.05) for the logistic model parameter between Red, UFLA and Commercial strains for fat, which presented a maximum fat deposition (0.23 g) at 310 days of age. Regarding ash deposition, the Commercial strain presented a higher maximum deposition (0.10 g) at 337 days, occurring later than the other strains that presented maximum deposition (0.033g) at 254 days of age. Thus, it was concluded that the genetic strains evaluated differ in chemical deposition curves of water, protein, fat and ash.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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

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The objective of this research was to use non-linear models to describe the growth pattern in Santa Ines sheep and to study the influence of environmental effects on curve parameters with the best-fit model. The models included the Brody, Richards, Von Bertalanffy, Gompertz, and Logistic models. We used 773 field reports on 162 animals ranging in age from 120 to 774 days, including 46 males and 116 females. The statistics used to evaluate the quality of fit included RMS (residual mean square), C% (percentage of convergence), R-2 (adjusted determination coefficient) and MAD (mean absolute deviation). Of the fixed effects studied, the only significant relationship was the effect of sex on parameter A. The Richards model was problematic during the process of convergence. Considering all studied criteria, the Logistic model presented the best fit in describing the growth pattern in Santa Ines sheep. (C) 2011 Elsevier B.V. All rights reserved.

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It is possible to determine the optimum time for permanence of vegetative propagules (mini-cuttings) inside a greenhouse for rooting, and this value can be used to optimize the structure of the nursery. The aim of this study was to determine the dynamics of adventitious rooting in mini-cuttings of three clones of Eucalyptus benthamii x Eucalyptus dunnii. Sprouts of H12, H19 and H20 clones were collected from mini-stumps that were planted in gutters containing sand and grown in a semi-hydroponic system. The basal region of the mini-cuttings was immersed in 2,000 mg L-1 indole-3-butyric acid (IBA) solution for 10 seconds. The rooting percentage of the mini-cuttings, the total length of the root system and the rooting rate per mini-cutting were also evaluated at 0 (time of planting), 7, 14, 21, 28, 35, 42, 49 and 56 days. We used logistic and exponential regression to mathematically model the speed of rhizogenesis. The rooting percentage was best represented as a logistic model, and the total length of the root system was best represented as an exponential model. The clones had different speeds of adventitious rooting. The optimum time for permanence of the mini-cuttings inside the greenhouse for rooting was between 35 and 42 days, and varied depending on the genetic material.

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In order to assess the contribution of different parenteral routes as risk exposure to the hepatitis C virus (HCV), samples from nine surveys or cross-sectional studies conducted in two Brazilian inland regions were pooled, including a total of 3,910 subjects. Heterogeneity among the study results for different risk factors was tested and the results were shown to be homogeneous. Anti-HCV antibodies were observed in 241 individuals, of which 146 (3.7%, 95% CI?=?3.24.4) had HCV exposure confirmed by immunoblot analysis or PCR test. After adjustment for relevant variables, a correlation between confirmed HCV exposure and injection drug use, tattooing, and advance age was observed. In a second logistic model that included exposures not searched in all nine studies, a smaller sample was analyzed, revealing an independent HCV association with past history of surgery and males who have sex with other males, in addition to repeated injection drug use. Overall, these analyses corroborate the finding that injection drug use is the main risk factor for HCV exposure and spread, in addition to other parenteral routes. J. Med. Virol. 84:756762, 2012. (C) 2012 Wiley Periodicals, Inc.

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Background: In a classical study, Durkheim mapped suicide rates, wealth, and low family density and realized that they clustered in northern France. Assessing others variables, such as religious society, he constructed a framework for the analysis of the suicide, which still allows international comparisons using the same basic methodology. The present study aims to identify possible significantly clusters of suicide in the city of Sao Paulo, and then, verify their statistical associations with socio-economic and cultural characteristics. Methods: A spatial scan statistical test was performed to analyze the geographical pattern of suicide deaths of residents in the city of Sao Paulo by Administrative District, from 1996 to 2005. Relative risks and high and/or low clusters were calculated accounting for gender and age as co-variates, were analyzed using spatial scan statistics to identify geographical patterns. Logistic regression was used to estimate associations with socioeconomic variables, considering, the spatial cluster of high suicide rates as the response variable. Drawing from Durkheim's original work, current World Health Organization (WHO) reports and recent reviews, the following independent variables were considered: marital status, income, education, religion, and migration. Results: The mean suicide rate was 4.1/100,000 inhabitant-years. Against this baseline, two clusters were identified: the first, of increased risk (RR = 1.66), comprising 18 districts in the central region; the second, of decreased risk (RR = 0.78), including 14 districts in the southern region. The downtown area toward the southwestern region of the city displayed the highest risk for suicide, and though the overall risk may be considered low, the rate climbs up to an intermediate level in this region. One logistic regression analysis contrasted the risk cluster (18 districts) against the other remaining 78 districts, testing the effects of socioeconomic-cultural variables. The following categories of proportion of persons within the clusters were identified as risk factors: singles (OR = 2.36), migrants (OR = 1.50), Catholics (OR = 1.37) and higher income (OR = 1.06). In a second logistic model, likewise conceived, the following categories of proportion of persons were identified as protective factors: married (OR = 0.49) and Evangelical (OR = 0.60). Conclusions: This risk/ protection profile is in accordance with the interpretation that, as a social phenomenon, suicide is related to social isolation. Thus, the classical framework put forward by Durkheim seems to still hold, even though its categorical expression requires re-interpretation.

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Background Synchronization programs have become standard in the dairy industry in many countries. In Switzerland, these programs are not routinely used for groups of cows, but predominantly as a therapy for individual problem cows. The objective of this study was to compare the effect of a CIDR-Select Synch and a 12-d CIDR protocol on the pregnancy rate in healthy, multiparous dairy cows in Swiss dairy farms. Methods Cows (N = 508) were randomly assigned to CIDR-Select Synch (N = 262) or 12-d CIDR (N = 246) protocols. Cows in the CIDR-Select Synch group received a CIDR and 2.5 ml of buserelin i.m. on d 0. On d 7, the CIDR insert was removed and 5 ml of dinoprost was administered i.m.. Cows in the 12-d CIDR group received the CIDR on d 0 and it was removed on d 12 (the routine CIDR protocol in Swiss dairies). On d 0 a milk sample for progesterone analysis was taken. Cows were inseminated upon observed estrus. Pregnancy was determined at or more than 35 days after artificial insemination. As a first step, the two groups were compared as to indication for treatment, breed, stud book, stall, pasture, and farmer's business using chi square tests or Fisher's exact test. Furthermore, groups were compared as to age, DIM, number of AI's, number of cows per farm, and yearly milk yield per cow using nonparametric ANOVA. A multiple logistic model was used to relate the success of the protocols to all of the available factors; in particular treatment (CIDR-Select Synch/12-d CIDR), milk progesterone value, age, DIM, previous treatment of the uterus, previous gynecological treatment, and number of preceding inseminations. Results The pregnancy rate was higher in cows following the CIDR-Select Synch compared to the 12-d CIDR protocol (50.4% vs. 22.4%; P < 0.0001). Conclusion The CIDR-Select Synch protocol may be highly recommended for multiparous dairy cows. The reduced time span of the progesterone insert decreased the number of days open, improved the pregnancy rate compared to the 12-d CIDR protocol and the cows did not to have to be handled more often.

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A great share of literature on social exclusion has been based mainly on the analysis of official survey data. Whereas these efforts have provided insights into the characteristics and conditions of those people living at the margins of mainstream social relations, they have however failed to encompass those who live beyond these very margins. Meanwhile, research on these hidden subpopulations, such as homeless and other vulnerable groups, remains generally less abundant and is significantly detached from the theoretical core of the debate on social exclusion. The concern about these shortcomings lies at the heart of our research. We seek to bring some light to the area by using data made available by an organization that provides services to people experiencing homelessness in Barcelona (Spain). The data sample contains clients in early stages of exclusion and others in chronic situations. Thus, we attempt to identify some of the variables that operate in preventing the "chronification" of those individuals in situation of social exclusion. Our findings suggest that certain variables such as educational level, income and housing type, which are considered to be central predictors in the analysis of poverty, behave differently when analyzing differences between stages of social exclusion. Although these results cannot be extrapolated to the whole Spanish or European reality, they could provide useful insight for future investigations on this topic.

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The objective was to examine the association between circumcision status and self-reported HIV infection among men who have sex with men (MSM) in Britain who predominantly or exclusively engaged in insertive anal intercourse. In 2007-2008, a convenience sample of MSM living in Britain was recruited through websites, in sexual health clinics, bars, clubs, and other venues. Men completed an online survey which included questions on circumcision status, HIV testing, HIV status, sexual risk behavior, and sexual role for anal sex. The analysis was restricted to 1,521 white British MSM who reported unprotected anal intercourse in the previous 3 months and who said they only or mostly took the insertive role during anal sex. Of these men, 254 (16.7 %) were circumcised. Among men who had had a previous HIV test (n = 1,097), self-reported HIV seropositivity was 8.6 % for circumcised men (17/197) and 8.9 % for uncircumcised men (80/900) (unadjusted odds ratio [OR], 0.97; 95 % confidence interval [95 % CI], 0.56, 1.67). In a multivariable logistic model adjusted for known risk factors for HIV infection, there was no evidence of an association between HIV seropositivity and circumcision status (adjusted OR, 0.79; 95 % CI, 0.43, 1.44), even among the 400 MSM who engaged exclusively in insertive anal sex (adjusted OR, 0.84; 95 % CI, 0.25, 2.81). Our study provides further evidence that circumcision is unlikely to be an effective strategy for HIV prevention among MSM in Britain.