Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2008.

Energy harvesting is becoming increasingly important in low-power applications where energy from the environment is used to power the system alone, or to supplement a battery. For example, pulse oximeter sensors inside helmets of road racing cyclists are powered by the sun. These sensors have become smaller and more practical without the limitation of a finite energy supply. Harvested energy from an energy transducer (solar, piezoelectric, etc.) must be maximized to ensure these devices can survive periods where environmental energy is scarce. The conversion process from the transducer to usable power for the device is not perfectly efficient. Specifically, the output voltage of a solar cell is a function of the light intensity, and by extension the load it powers. A small perturbation of the light source quickly diminishes the available power. The wasted power reduces the energy available for the application, and can be improved using an approach called maximum power point tracking (MPPT). This technique maximizes harvesting efficiency by dynamically impedance matching the transducer to its load. This report introduces the Maximum Efficient Solar Harvester (MESH), an MPPT algorithm tuned for a specific Wireless Sensor Network (WSN) application. MESH specifically controls the operation of the DC-DC converter in a solar power management unit (PMU). The control is done by monitoring the available light and feeding that information to choose the optimal operating point DC-DC converter. This operating point has a direct dependency on the overall efficiency of the system. For MESH to be practical, the cost and power overhead of adding this functionality must be assessed. Empirical results indicate that MESH improves the maximum efficiency of the popular Texas Instruments (TI) RF2500-SEH WSN platform by an average of 20%, which far exceeds the power overhead it incurs. The cost is also found to be minimal, as WSN platforms already include a large portion of the hardware required to implement MESH. The report was done in collaboration with Shahil Rais. It covers the hardware components and the bench automation environment; Rais's companion report focuses on software implementation and MESH architecture definition. / text

This thesis which consists of four papers is concerned with estimation methods in factor analysis and structural equation models. New estimation methods are proposed and investigated. In paper I an approximation of the penalized maximum likelihood (ML) is introduced to fit an exploratory factor analysis model. Approximated penalized ML continuously and efficiently shrinks the factor loadings towards zero. It naturally factorizes a covariance matrix or a correlation matrix. It is also applicable to an orthogonal or an oblique structure. Paper II, a simulation study, investigates the properties of approximated penalized ML with an orthogonal factor model. Different combinations of penalty terms and tuning parameter selection methods are examined. Differences in factorizing a covariance matrix and factorizing a correlation matrix are also explored. It is shown that the approximated penalized ML frequently improves the traditional estimation-rotation procedure. In Paper III we focus on pseudo ML for multi-group data. Data from different groups are pooled and normal theory is used to fit the model. It is shown that pseudo ML produces consistent estimators of factor loadings and that it is numerically easier than multi-group ML. In addition, normal theory is not applicable to estimate standard errors. A sandwich-type estimator of standard errors is derived. Paper IV examines properties of the recently proposed polychoric instrumental variable (PIV) estimators for ordinal data through a simulation study. PIV is compared with conventional estimation methods (unweighted least squares and diagonally weighted least squares). PIV produces accurate estimates of factor loadings and factor covariances in the correctly specified confirmatory factor analysis model and accurate estimates of loadings and coefficient matrices in the correctly specified structure equation model. If the model is misspecified, robustness of PIV depends on model complexity, underlying distribution, and instrumental variables.

Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2008.

Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2008.

In traditional forensic DNA casework, the inclusion or exclusion of individuals who may have contributed to an item of evidence may be dependent upon the assumption on the number of individuals from which the evidence arose. Typically, the determination of the minimum number of contributors (NOC) to a mixture is achieved by counting the number of alleles observed above a given analytical threshold (AT); this technique is known as maximum allele count (MAC). However, advances in polymerase chain reaction (PCR) chemistries and improvements in analytical sensitivities have led to an increase in the detection of complex, low template DNA (LtDNA) mixtures for which MAC is an inadequate means of determining the actual NOC. Despite the addition of highly polymorphic loci to multiplexed PCR kits and the advent of interpretation softwares which deconvolve DNA mixtures, a gap remains in the DNA analysis pipeline, where an effective method of determining the NOC needs to be established. The emergence of NOCIt -- a computational tool which provides the probability distribution on the NOC, may serve as a promising alternative to traditional, threshold- based methods. Utilizing user-provided calibration data consisting of single source samples of known genotype, NOCIt calculates the a posteriori probability (APP) that an evidentiary sample arose from 0 to 5 contributors. The software models baseline noise, reverse and forward stutter proportions, stutter and allele dropout rates, and allele heights. This information is then utilized to determine whether the evidentiary profile originated from one or many contributors. In short, NOCIt provides information not only on the likely NOC, but whether more than one value may be deemed probable. In the latter case, it may be necessary to modify downstream interpretation steps such that multiple values for the NOC are considered or the conclusion that most favors the defense is adopted. Phase I of this study focused on establishing the minimum number of single source samples needed to calibrate NOCIt. Once determined, the performance of NOCIt was evaluated and compared to that of two other methods: the maximum likelihood estimator (MLE) -- accessed via the forensim R package, and MAC. Fifty (50) single source samples proved to be sufficient to calibrate NOCIt, and results indicate NOCIt was the most accurate method of the three. Phase II of this study explored the effects of template mass and sample complexity on the accuracy of NOCIt. Data showed that the accuracy decreased as the NOC increased: for 1- and 5-contributor samples, the accuracy was 100% and 20%, respectively. The minimum template mass from any one contributor required to consistently estimate the true NOC was 0.07 ng -- the equivalent of approximately 10 cells' worth of DNA. Phase III further explored NOCIt and was designed to assess its robustness. Because the efficacy of determining the NOC may be affected by the PCR kit utilized, the results obtained from NOCIt analysis of 1-, 2-, 3-, 4-, and 5-contributor mixtures amplified with AmpFlstr® Identifiler® Plus and PowerPlex® 16 HS were compared. A positive correlation was observed for all NOCIt outputs between kits. Additionally, NOCIt was found to result in increased accuracies when analyzed with 1-, 3-, and 4-contributor samples amplified with Identifiler® Plus and with 5-contributor samples amplified with PowerPlex® 16 HS. The accuracy rates obtained for 2-contributor samples were equivalent between kits; therefore, the effect of amplification kit type on the ability to determine the NOC was not substantive. Cumulatively, the data indicate that NOCIt is an improvement to traditional methods of determining the NOC and results in high accuracy rates with samples containing sufficient quantities of DNA. Further, the results of investigations into the effect of template mass on the ability to determine the NOC may serve as a caution that forensic DNA samples containing low-target quantities may need to be interpreted using multiple or different assumptions on the number of contributors, as the assumption on the number of contributors is known to affect the conclusion in certain casework scenarios. As a significant degree of inaccuracy was observed for all methods of determining the NOC at severe low template amounts, the data presented also challenge the notion that any DNA sample can be utilized for comparison purposes. This suggests that the ability to detect extremely complex, LtDNA mixtures may not be commensurate with the ability to accurately interpret such mixtures, despite critical advances in software-based analysis. In addition to the availability of advanced comparison algorithms, limitations on the interpretability of complex, LtDNA mixtures may also be dependent on the amount of biological material present on an evidentiary substrate.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-03-09T18:24:30Z No. of bitstreams: 1 teto completo.pdf: 1474140 bytes, checksum: c2aec33e8cc4c08a3cea64ea7bb18d3c (MD5) / Made available in DSpace on 2017-03-09T18:24:30Z (GMT). No. of bitstreams: 1 teto completo.pdf: 1474140 bytes, checksum: c2aec33e8cc4c08a3cea64ea7bb18d3c (MD5) Previous issue date: 2005-02-14 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Objetivou-se estudar o efeito de diferentes turnos de rega e níveis de irrigação sobre Panicum maximum Jacq. cv. Tanzânia. O capim foi cultivado em recipientes sob condições de ambiente protegido no período de janeiro a outubro de 2004. As irrigações foram realizadas com turnos de rega de 1, 4 e 7 dias, e lâminas de irrigação para restabelecer 50, 75 e 100% da disponibilidade total de água no solo. Aos 46 dias após a semeadura, procedeu-se o corte de uniformização. A partir de então, foram realizados quatro cortes para avaliação. A evapotranspiração da cultura (ETc) foi obtida por meio de quatro lisímetros de drenagem. Foram avaliados durante o experimento a densidade populacional de perfilhos, características morfogênicas, produtividade e teor de matéria seca (MS), eficiência do uso da água (EUA), composição bromatológica, digestibilidade "in vitro" da matéria seca (DIVMS), a distribuição e a profundidade efetiva do sistema radicular. O perfilhamento foi maior para maior nível de irrigação. O clima proporcionou maior efeito nas características morfogênicas que os tratamentos. Turno de rega diário proporcionou maiores taxa de aparecimento de folhas (TApF) no período em que a temperatura e a radiação foram superiores, período esse responsável também pelas maiores taxas de alongamento de colmo (TAlC). A taxa de alongamento de folhas (TAlF) foi superior no tratamento que apresentou o menor consumo de água. Os fatores estudados não proporcionaram efeito expressivo no número de folhas emergentes (NFEm), expandidas (NFEx) e vivas (NFV). A produtividade de MS aumentou à medida que aumentou o nível de irrigação e diminuiu o turno de rega. O teor de MS foi maior conforme se aumentou o nível de irrigação. Os valores de EUA foram menores no corte realizado no período de menores temperaturas, mostrando o efeito da sazonalidade. Existiu uma relação diretamente proporcional entre a EUA e o fator turno de rega. O teor de proteína bruta (PB) foi maior quanto menor foi a quantidade de água aplicada. Os teores de DIVMS foram inversamente proporcionais aos teores de fibra em detergente ácido (FDA). A profundidade efetiva do sistema radicular foi maior quanto maiores o turno de rega e o nível de irrigação. / The aim of this work was to study the effect of different irrigation frequency and levels of irrigation on Panicum maximum Jacq. cv Tanzania. The grass was cultivated in recipients inside greenhouse, in the period of January to October 2004. The irrigations were performed with a frequency of 1, 4 and 7 days, in order to reestablish soil water content to 50, 75 and 100% of the total available water in the soil. Forty-six days after the seeds had been sowed, an unifomization cut was performed, and after that, four cuts for evaluation were accomplished. The crop evapotranspiration (ETc) was obtained by means of four drainage lysimeters. During the experiments the tiller population density, morphogenetical characteristics, yield and the grass dry matter content (DM), water use efficiency (WUE), chemical composition of the grass, in vitro dry matter digestibility (IVDMD), the root distribution and the effective root depth were evaluated. The tillering was bigger for the highest level of irrigation. The climate provided a more significant effect on the morphogenetical characteristics than the treatments. The irrigation frequency provided a larger leaf appearance rate (LAR) in the period when temperature and radiation were higher. This period was also responsible for the biggest steam elongation rate (SER). The leaf elongation rate (LER) was superior in the treatment that showed the least consumption of water. The studied factors did not provide an expressive effect on the emerging leaf numbers (EmLN), expanded leaf numbers (ExLN) and living leaf numbers (ALN). The productivity of DM increased for the irrigations that reestablished higher soil moisture and irrigation frequency. The grass dry matter increased with the irrigation depth. The WUE values were smaller in the cut accomplished in the periods of low temperatures, showing the effect of seasonalness. A proportional relation between the WUE and the irrigation frequency occurred. The crude protein (CD) increased as the irrigation depth decreased. The IVDMD were inversely proportional to the acid detergent fiber (ADF). The effective root depth was larger as the irrigation frequency and the irrigation depth increased. / Dissertação importada do Alexandria

GONÇALVES, Josemir de Souza. Composição química e fracionamento dos carboidratos da biomassa de panicum maximum cv. Tanzânia sob três períodos de descanso. 2006. 82 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Zootecnia, Fortaleza-CE, 2006 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-01T14:52:50Z No. of bitstreams: 1 2006_dis_jsgoncalves.pdf: 500928 bytes, checksum: dfb947038c644cea8d4a1a6e84dfd74a (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-01T14:53:17Z (GMT) No. of bitstreams: 1 2006_dis_jsgoncalves.pdf: 500928 bytes, checksum: dfb947038c644cea8d4a1a6e84dfd74a (MD5) / Made available in DSpace on 2016-08-01T14:53:17Z (GMT). No. of bitstreams: 1 2006_dis_jsgoncalves.pdf: 500928 bytes, checksum: dfb947038c644cea8d4a1a6e84dfd74a (MD5) Previous issue date: 2006 / The experiment was carried out in the advanced field of the Forage Research Sector - NPF (www.npf.ufc.br) located in the Experimental Farm of the Vale do Curu - FEVC, belonging to Federal University of Ceará - UFC. The objective was evaluate the chemical composition and the carbohydrate fractionation of Panicum maximum cv. Tanzânia biomass under three rest periods (RPs) based in the new leaf (L) number expanded for tiller (1.5; 2.5 and 3.5L). Was used the completely randomized design in a factorial arrangement 3x3 (3 fractions and 3 RPs). The harvest of the samples was made before the entrance and after the exit the animals the poles. Later, the samples had been separate in the fractions leaf, culm and death material, being droughts in greenhouse of forced ventilation 65° C for 72 hours, and processed. In the Laboratory of Animal Nutrition of the Animal Science Department of UFC (LNA/DZ/UFC), were determined the levels of Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), Hemi-cellulose (HC), Cellulose (CEL), Lignin (LIG), Etereal Extract (EE), Crude Protein (PB), Insoluble Nitrogen in Neutral Detergent (INND), Insoluble Nitrogen in Acid Detergent (INAD), Total Total Carbohydrates (TC), Non Fiber Carbohydrates (NFC), and of the fractions that compose the TC: A+B1, B2 and C. The levels of NDF and ADF had been raised (P<0.05) with the advance of the RPs. The entire plant (EP) of the grass under bigger RP (3.5L), in the before grazing, presented levels, respectively, of 74.0 and 46.3% being these raising for 77,3 and 50,9% after grazing. The levels of LIG of leaf fraction of the grass under RP 3.5L (4.2%) had suffered rises (P<0.05) after grazing. The LIG levels in the RP were higher (P<0.05) in those submitted to 3.5L RP in comparison to the EPs of the 1.5L RP in such a way in before grazing (4.7 and 5.3%) how much after grazing (4.7 and 5.3%). The biggest levels of PB of the leaf fraction had been found in the grass under 1.5L RP (10,86 and 8.59%), before grazing and after grazing. The levels of CP in the entire plant had varied of 8.8 6.4% (P<0.05) and 6.16 and 4.4% (P<0.05) between 3.5 and 1.5L RPs, respectively before and after grazing. The INAD levels, had been also raised (P<0.05) in the EP of 3.5L RP (20.3 and 28.5%), respectively before and after grazing. The levels of TC of the leaf fraction and the EP had presented average levels (P>0.05) of 75.4 and 77.4% before grazing and 79.2 and 89.2% after grazing. The C carbohydrates fraction presented average between 11.4 11.9%, in the leaf fraction, whereas in the EP of the grass under 3.5L RP, had been observed biggest levels (P<0.05) of this fraction (14.3 and 15.7), in both cases when observed before grazing and pos-grazing. The Tanzânia grass under 1.5L RP presented the best chemical composition of that they had been evaluated. However, it is necessary that information on the chemical composition of the grass are taken in consideration in set with the occured changes in the structure of the grass so that if can have a bigger exactness in the evaluation of the quality of the grass. / O experimento foi conduzido no campo avançado do Núcleo de Pesquisa em Forragicultura - NPF (www.npf.ufc.br) localizado na Fazenda Experimental do Vale do Curu – FEVC, pertencente à Universidade Federal do Ceará – UFC. Objetivou-se avaliar a composição química e o fracionamento dos carboidratos da biomassa de Panicum maximum cv. Tanzânia sob três períodos de descanso (PDs) baseados no número de novas folhas expandidas por perfilho (1,5; 2,5 e 3,5F). Utilizou-se o delineamento inteiramente casualizado em arranjo fatorial 3x3 (3 frações e 3 PDs). A colheita das amostras foi feita antes da entrada e após a saída dos animais dos piquetes. Posteriormente, as amostras foram separadas nas frações folha, colmo e material morto. No Laboratório de Nutrição Animal do Departamento de Zootecnia da UFC (LNA/DZ/UFC), foram determinados os teores de Fibra em Detergente Neutro (FDN), Fibra em Detergente Ácido (FDA), Hemicelulose (HEM), Celulose (CEL), Lignina (LIG), Extrato Etéreo (EE), Proteína Bruta (PB), Nitrogênio Insolúvel em Detergente Neutro (NIDN), Nitrogênio Insolúvel em Detergente Ácido (NIDA), Carboidratos Totais (CT), Carboidratos Não Fibrosos (CNF), e das frações que compõem os CT: A+B1, B2 e C. Os teores de FDN e de FDA foram elevados (P<0,05) com o avanço dos PDs. A planta inteira (PI) do pasto sob maior PD (3,5F), no pré-pastejo, apresentou teores, respectivamente, de 74,0 e 46,3% sendo estes elevados para 77,3 e 50,9% no pós pastejo. Os teores de LIG da fração folha do pasto sob PD 3,5F (4,2%) sofreram elevações (P<0,05) no pré-pastejo. Os teores de LIG na PI foram superiores (P<0,05) naquelas submetidas ao PD 3,5F em comparação às PIs do PD 1,5F tanto no pré-pastejo (4,7 e 5,3%) quanto no pós-pastejo (4,7 e 5,3%). Os maiores teores de PB da fração folha foram encontrados nos pastos sob PD 1,5F (10,9 e 8,6%), no pré e pós-pastejo. Os teores de PB na planta inteira variaram de 8,8 a 6,4% (P<0,05) e 6,2 e 4,4% (P<0,05) entre os PDs 1,5 e 3,5F, respectivamente no pré e pós-pastejo. Os teores de NIDA, também foram elevados (P<0,05) na PI do PD 3,5F (20,3 e 28,5%), respectivamente no pré e pós-pastejo. Os teores de CT da fração folha e da PI apresentaram teores médios (P>0,05) de 75,4 e 77,4% no pré-pastejo e 79,2 e 89,2% no pós pastejo. A fração C dos carboidratos apresentou variação média de 11,4 a 11,9%, na fração folha, enquanto que na PI do pasto sob PD 3,5 F, foram observados os maiores teores (P<0,05) desta fração (14,4 e 15,7%), em ambos os casos quando observados no pré e pós-pastejo. O pasto de capim Tanzânia manejado sob PD 1,5F apresentou a melhor composição química dos que foram avaliados. Contudo é necessário que informações sobre a composição química dos pastos sejam levadas em consideração em conjunto com as mudanças ocorridas na estrutura do pasto para que se possa ter uma maior exatidão na avaliação da qualidade dos pastos.

Made available in DSpace on 2015-03-26T13:54:45Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1035278 bytes, checksum: cd0b4ec2584b32a8c251f36a35369a30 (MD5) Previous issue date: 2008-07-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The trail was conducted with the aim to evaluate the nitrogen and plant density influence on the morphogenetic and structural characteristics of established tanzaniagrass (Panicum maximum Jacq.) plots. The experiment was conducted in the Forage Sector of Animal Science Department of Universidade Federal de Viçosa, from November 2007 to March 2008. The used design was in complete randomized blocks with two replications in a factorial arrangement with four nitrogen supplies (0, 80, 160, 320 kg.ha-1 N) and three plant densities (9, 25 e 49 plant.m-2). The plots were cut at 25 cm from soil level when the canopy reached 95 % of light interception. The response variables evaluated were the leaf appearance rate, phyllochron, leaf elongation rate, stem elongation rate, senescence rate, number of live leafs, leaf life duration and number of total, basilar and aerial tillers per clump. In the tillering dynamics, were evaluated the appearance and mortality rates of total, basilar and aerial tillers. The leaf appearance and stem elongation rate were influenced linear and positively by the nitrogen levels, while the phyllochron and life leaf duration varied linear and negatively. The leaf elongation rate showed exponential response to nitrogen fertilization and quadratic response to plant densities, with bigger rates being observed in the 320 kg.ha-1 N dose and 49 plant.m-2 density. The senescense rate and number of live leafs were not influenced by the factors evaluated, presenting 4.7 leafs.tiller-1 and 0.56 cm.day-1, respectively. The number of total, basilar and aerial tillers per clump showed exponential response to the nitrogen dose and quadratic response to plants density. The nitrogen increased the number in all tiller classes, while the plant density influenced negatively, with less tillers in the 25 and 49 plants.m-2 densities. The tillering dynamics were influenced quadratically by nitrogen, plant density, and by the interaction between these factors. The total and basilar tiller appearance were influenced quadratically by nitrogen dose, with bigger values had been observed on the 160 and 320 kg.ha-1 N doses. The plant density influenced quadratically the total tiller appearance, which was higher in the 25 plant.m-2 density. On the other hand, the aerial tiller appearance rate was not influenced by the nitrogen doses and plant densities. The total tiller mortality rate was influenced quadratically by the nitrogen doses and plant densities, in a way that it was estimated less mortality in 32 plant.m-2 density and highest mortality in 212 kg.ha-1 N dose. In addition, the basilar tiller mortality rate was influenced quadratically by the plant densities, with less mortality observed in 32 plant.m-2 density. The aerial tiller mortality rate was influenced linearly by the nitrogen doses, with highest mortality in the 320 kg.ha-1dose. The nitrogen fertilization increases, in this way, leafs and tiller production in established tanzaniagrass cut on the 95 % canopy light interception. Nevertheless, the density influence on the morphogenetic characteristics is little outstanding, with its main effects on the number of tillers per clump, which decreases under high densities. Either the plant density or the nitrogen supply influence the tiller dynamics of tanzaniagrass. The appearance and mortality rates are increased under high nitrogen levels. The tiller appearance rate is bigger in intermediary densities, while the mortality rate decreases under high plant densities. Thus, pastures established under low and intermediary densities show more intense tiller renovation. / Objetivou-se com este trabalho avaliar o efeito da adubação nitrogenada e da densidade de plantas nas características morfogênicas e estruturais do capim-tanzânia (Panicum maximum Jacq.) estabelecido. O experimento foi conduzido em área pertencente ao Setor Forragicultura do Departamento de Zootecnia da Universidade Federal de Viçosa no período de novembro de 2007 a março de 2008. O delineamento experimental utilizado foi o de blocos completos casualizados, com 12 tratamentos e duas repetições em esquema fatorial 4 × 3, com quatro doses de nitrogênio (ausência de aplicação, 80, 160 e 320 kg.ha-1.ano) e três densidades de plantas (9, 25 e 49 plantas.m-2). O corte das plantas foi realizado a 25 cm do solo quando o dossel interceptava 95% da luz incidente. Foram avaliados a taxa de aparecimento foliar, o filocrono, a taxa de alongamento foliar, a taxa de alongamento de pseudocolmo, a taxa de senescência foliar, o número de folhas vivas, a duração da vida das folhas e o número de perfilhos totais, basilares e aéreos por touceira. Na dinâmica de perfilhamento, foram avaliadas as taxas de aparecimento e mortalidade dos perfilhos totais, basilares e aéreos. As taxas de aparecimento foliar e alongamento de pseudocolmos foram influenciadas linear e positivamente pela adubação com nitrogênio, enquanto o filocrono e a duração da vida das folhas foram influenciados de forma linear negativa. A taxa de alongamento foliar apresentou resposta exponencial à adubação nitrogenada e resposta quadrática às densidades de planta, com maiores taxas sendo observadas na dose de 320 kg.ha-1 e na densidade de 49 plantas.m-2. A taxa de senescência foliar e o número de folhas vivas não foram influenciados pelos fatores avaliados e apresentaram valores médios de 4,7 folhas.perfilho-1 e 0,56 cm.dia-1, respectivamente. Os números de perfilhos totais, basilares e aéreos por touceira foram influenciados de forma exponencial pelas doses de nitrogênio e de forma quadrática pelas densidades de planta. O nitrogênio promoveu aumento no número de perfilhos de todas classes, enquanto a densidade influenciou negativamente essa variável, de modo que os menores números de perfilhos totais, basilares e aéreos foram observados nas densidades de 25 e 49 plantas.m-2. As doses de nitrogênio, a densidade de plantas e a interação entre esses fatores tiveram efeito sobre a dinâmica de perfilhamento. As taxas de aparecimento de perfilhos totais e basilares foram influenciadas quadraticamente pelas doses de nitrogênio, de modo que os maiores valores foram obtidos nas doses de 160 e 320 kg.ha-1. A densidade influenciou de forma quadrática o aparecimento de perfilhos totais, que foi maior na densidade de 25 plantas.m-2. A taxa de aparecimento de perfilhos aéreos, no entanto, não foi influenciada pelas doses de nitrogênio nem pelas densidades de plantas. A taxa de mortalidade de perfilhos totais foi influenciada de forma quadrática pelas doses de nitrogênio e pelas densidades de plantas e foi menor na densidade de 32 plantas.m-2 e maior na dose de 212 kg.ha-1 de nitrogênio. A taxa de mortalidade de perfilhos basilares, por sua vez, foi influenciada de forma quadrática pelas densidades de plantas, e foi menor na densidade de 32 plantas.m-2. As doses de nitrogênio tiveram efeito linear na taxa de mortalidade de perfilhos aéreos, que foi maior na dose de 320 kg.ha-1. A adubação nitrogenada aumenta a produção de folhas e perfilhos em capim-tanzânia submetido ao corte aos 95% de interceptação de luz, todavia, a influência da densidade de plantas sobre as características morfogênicas é pouco acentuada, pois os maiores efeitos foram observados somente sobre o número de perfilhos por touceira, que é reduzido sob altas densidades. Tanto a densidade de plantas como a adubação nitrogenada influenciam a dinâmica de perfilhamento do capim-tanzânia, uma vez que as taxas de aparecimento e mortalidade são estimuladas em altas doses desse nutriente. O aparecimento de perfilhos totais é favorecido em densidades intermediárias, enquanto a mortalidade reduz nas maiores densidades de plantas, assim, pastos implantados em densidades baixas e intermediárias apresentam padrão mais intenso de renovação de perfilhos.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O experimento foi conduzido no campo avanÃado do NÃcleo de Pesquisa em Forragicultura - NPF (www.npf.ufc.br) localizado na Fazenda Experimental do Vale do Curu â FEVC, pertencente à Universidade Federal do Cearà â UFC. Objetivou-se avaliar a composiÃÃo quÃmica e o fracionamento dos carboidratos da biomassa de Panicum maximum cv. TanzÃnia sob trÃs perÃodos de descanso (PDs) baseados no nÃmero de novas folhas expandidas por perfilho (1,5; 2,5 e 3,5F). Utilizou-se o delineamento inteiramente casualizado em arranjo fatorial 3x3 (3 fraÃÃes e 3 PDs). A colheita das amostras foi feita antes da entrada e apÃs a saÃda dos animais dos piquetes. Posteriormente, as amostras foram separadas nas fraÃÃes folha, colmo e material morto. No LaboratÃrio de NutriÃÃo Animal do Departamento de Zootecnia da UFC (LNA/DZ/UFC), foram determinados os teores de Fibra em Detergente Neutro (FDN), Fibra em Detergente Ãcido (FDA), Hemicelulose (HEM), Celulose (CEL), Lignina (LIG), Extrato EtÃreo (EE), ProteÃna Bruta (PB), NitrogÃnio InsolÃvel em Detergente Neutro (NIDN), NitrogÃnio InsolÃvel em Detergente Ãcido (NIDA), Carboidratos Totais (CT), Carboidratos NÃo Fibrosos (CNF), e das fraÃÃes que compÃem os CT: A+B1, B2 e C. Os teores de FDN e de FDA foram elevados (P<0,05) com o avanÃo dos PDs. A planta inteira (PI) do pasto sob maior PD (3,5F), no prÃ-pastejo, apresentou teores, respectivamente, de 74,0 e 46,3% sendo estes elevados para 77,3 e 50,9% no pÃs pastejo. Os teores de LIG da fraÃÃo folha do pasto sob PD 3,5F (4,2%) sofreram elevaÃÃes (P<0,05) no prÃ-pastejo. Os teores de LIG na PI foram superiores (P<0,05) naquelas submetidas ao PD 3,5F em comparaÃÃo Ãs PIs do PD 1,5F tanto no prÃ-pastejo (4,7 e 5,3%) quanto no pÃs-pastejo (4,7 e 5,3%). Os maiores teores de PB da fraÃÃo folha foram encontrados nos pastos sob PD 1,5F (10,9 e 8,6%), no prà e pÃs-pastejo. Os teores de PB na planta inteira variaram de 8,8 a 6,4% (P<0,05) e 6,2 e 4,4% (P<0,05) entre os PDs 1,5 e 3,5F, respectivamente no prà e pÃs-pastejo. Os teores de NIDA, tambÃm foram elevados (P<0,05) na PI do PD 3,5F (20,3 e 28,5%), respectivamente no prà e pÃs-pastejo. Os teores de CT da fraÃÃo folha e da PI apresentaram teores mÃdios (P>0,05) de 75,4 e 77,4% no prÃ-pastejo e 79,2 e 89,2% no pÃs pastejo. A fraÃÃo C dos carboidratos apresentou variaÃÃo mÃdia de 11,4 a 11,9%, na fraÃÃo folha, enquanto que na PI do pasto sob PD 3,5 F, foram observados os maiores teores (P<0,05) desta fraÃÃo (14,4 e 15,7%), em ambos os casos quando observados no prà e pÃs-pastejo. O pasto de capim TanzÃnia manejado sob PD 1,5F apresentou a melhor composiÃÃo quÃmica dos que foram avaliados. Contudo à necessÃrio que informaÃÃes sobre a composiÃÃo quÃmica dos pastos sejam levadas em consideraÃÃo em conjunto com as mudanÃas ocorridas na estrutura do pasto para que se possa ter uma maior exatidÃo na avaliaÃÃo da qualidade dos pastos. / The experiment was carried out in the advanced field of the Forage Research Sector - NPF (www.npf.ufc.br) located in the Experimental Farm of the Vale do Curu - FEVC, belonging to Federal University of Cearà - UFC. The objective was evaluate the chemical composition and the carbohydrate fractionation of Panicum maximum cv. TanzÃnia biomass under three rest periods (RPs) based in the new leaf (L) number expanded for tiller (1.5; 2.5 and 3.5L). Was used the completely randomized design in a factorial arrangement 3x3 (3 fractions and 3 RPs). The harvest of the samples was made before the entrance and after the exit the animals the poles. Later, the samples had been separate in the fractions leaf, culm and death material, being droughts in greenhouse of forced ventilation 65 C for 72 hours, and processed. In the Laboratory of Animal Nutrition of the Animal Science Department of UFC (LNA/DZ/UFC), were determined the levels of Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), Hemi-cellulose (HC), Cellulose (CEL), Lignin (LIG), Etereal Extract (EE), Crude Protein (PB), Insoluble Nitrogen in Neutral Detergent (INND), Insoluble Nitrogen in Acid Detergent (INAD), Total Total Carbohydrates (TC), Non Fiber Carbohydrates (NFC), and of the fractions that compose the TC: A+B1, B2 and C. The levels of NDF and ADF had been raised (P<0.05) with the advance of the RPs. The entire plant (EP) of the grass under bigger RP (3.5L), in the before grazing, presented levels, respectively, of 74.0 and 46.3% being these raising for 77,3 and 50,9% after grazing. The levels of LIG of leaf fraction of the grass under RP 3.5L (4.2%) had suffered rises (P<0.05) after grazing. The LIG levels in the RP were higher (P<0.05) in those submitted to 3.5L RP in comparison to the EPs of the 1.5L RP in such a way in before grazing (4.7 and 5.3%) how much after grazing (4.7 and 5.3%). The biggest levels of PB of the leaf fraction had been found in the grass under 1.5L RP (10,86 and 8.59%), before grazing and after grazing. The levels of CP in the entire plant had varied of 8.8 6.4% (P<0.05) and 6.16 and 4.4% (P<0.05) between 3.5 and 1.5L RPs, respectively before and after grazing. The INAD levels, had been also raised (P<0.05) in the EP of 3.5L RP (20.3 and 28.5%), respectively before and after grazing. The levels of TC of the leaf fraction and the EP had presented average levels (P>0.05) of 75.4 and 77.4% before grazing and 79.2 and 89.2% after grazing. The C carbohydrates fraction presented average between 11.4 11.9%, in the leaf fraction, whereas in the EP of the grass under 3.5L RP, had been observed biggest levels (P<0.05) of this fraction (14.3 and 15.7), in both cases when observed before grazing and pos-grazing. The TanzÃnia grass under 1.5L RP presented the best chemical composition of that they had been evaluated. However, it is necessary that information on the chemical composition of the grass are taken in consideration in set with the occured changes in the structure of the grass so that if can have a bigger exactness in the evaluation of the quality of the grass.