Voluntary intake of Tanzania grass (Panicum maximum) under rotational grazing by lactating cows

The study was conducted at Nucleo de Pesquisas Zootecnicas Nordeste of the Instituto de Zootecnia, Ribeirao Preto, SP, in a rotational grazing area of Tanzania grass (Panicum maximum), to estimate the dry matter intake by lactanting cows. The estimation of dry matter intake was calculated from the feces production estimated using extrusa Chromium-mordent and the in vitro digestibility of diet. The three treatments were crossbreed cows fed 3 kg.day(-1) of concentrate, crossbred cows without concentrate suplementation and pure Gir cows also without concentrate supplementation. The milk production was 11.98, 6.53 and 5.46 kg per cow per day, the grass intake was 8.26 +/- 5.66, 11.01 +/- 5.37 and 9.55 +/- 2.31 kg of dry matter per day or 2.15%, 2.37% and 2.34% of live weight for the three experimental groups respectively. The milk production was higher (P<0.01) for cows fed with concentrate. No difference was found for dry matter intake.

Densification and residual stresses induced in glass surfaces by Vickers indentations

Images and profiles of Vickers impressions produced on as-received float-glass were obtained using atomic force microscopy (AFM). The images show that the impression edges undergo elastic recovery parallel to surface. The profiles made it possible to measure vertical elastic recovery, ev(r). For a 40 g nominal load, maximum penetration depth of indenter was (2.20 ± 0.03) μm, and recovery at the impression center was ev(0) = (0.98 ± 0.03) μm. Vertical elastic recovery was non-uniform along profiles. Permanent impressions produced resulted from glass mass displacement downward, producing an increase in glass density in impression vicinity, which is discussed in terms of changes in O-Si-O and Si-O-Si bond angles and Si-O bond length. Near impression edges, pileup was observed for which a simplified model is proposed taking into account the compaction and stresses near the impressions. © 2000 Elsevier Science B.V. All rights reserved.

Efeito da densidade de plantas de Panicum maximum Jacq. sobre o crescimento inicial de Eucalyptus grandis W.Hill ex Maiden

In order to verify the effect of Panicum maximum plant density on the initial growth of Eucalyptus grandis plants, one assay was conducted under semi-controlled conditions of soil fertility and humidity. Dark red Latossol, collected from the arable layer, was used as substrate in 50 liters amianthus cement boxes. One seedling of Eucalyptus was planted in each box. Fifteen days later, seedlings of P. maximum were transplanted on the same box. The treatments consisted of 0, 4, 8, 12, 16 and 20 plants of P. maximum per m 2. The experimental design was the complete randomized design, with six treatments and eight replicates for P. maximum. One hundred and ten and 190 days after transplanting, Eucalyptus plants grown among P. maximum showed an average reduction of 30.80 and 46.55% stem diameter, 25.10 and 22.50 plant high, 40.18 and 31.29% stem dry weight, 61.32 and 54.06% branch dry weight, 53.72 and 51.82% root dry weight, 44.62 and 38.50% leaf dry weight, 22.51 and 23.16 branch number, 20.72 and 19.97% leaf number, and 33.88 and 17.05% leaf area, respectively.

Synthesis and crystal phase evaluation of hydroxylapatite using the rietveld-maximum entropy method

Bioceramic systems based on hydroxylapatite (HAP) are an important class of bioactive materials that may promote bone regeneration. The aim of this research was to evaluate how the stoichiometry of HAP influences its microstructural properties when diagnosed using the combined Rietveld method and Maximum entropy method (MEM). The Rietveld Method (RM) is recognizably a powerful tool used to obtain structural and microstructural information of polycrystalline samples analyzed by x-ray diffraction. Latterly have combined the RM with the maximum entropy method (MEM), with the goal of improve structural refinement results. The MEM provides high resolution maps of electron density and their analysis leave the accurate localization of atoms inside of unit cell. Like that, cycles Rietveld-MEM allow an excellent structural refinement In this work, a hydroxylapatite sample obtained by emulsion method had its structure refined using one cycle Rietveld-MEM with x-ray diffraction data. The indices obtained in initial refinement was Rwp = 7.50%, Re = 6.56%, S - 1.14% e RB = 1.03%. After MEM refinement and electron densities maps analysis to correction of atomics positions, the news indicators of Rietveld refinement quality was Rwp = 7.35%, Re = 6.56%, S = 1.12% and RB = 0.75%. The excellent result obtained to RB shows the efficiency of MEM as auxiliary in the refinement of structure of hydroxylapatite by RM.

Characteristics of the double-torsion test to determine the R-curve of ceramic materials

Double-torsion tests were carried out on a commercial ceramic floor tile to verify whether this test is suitable for determining the R-curve of ceramics. The instantaneous crack length was obtained by means of compliance calibration, and it was found that the experimental compliance underestimates the real crack length. The load vs. displacement curves were also found to drop after maximum loading, causing the stress intensity factor to decline. The R-curves were calculated by two methods: linear elastic fracture mechanics and the energetic method. It was obtained that the average values of crack resistance, R, and the double of the work of fracture, 2 · γwof, did not depend on notch length, a0, which is a highly relevant finding, indicating that these parameters were less dependent on the test specimen's geometry. The proposal was to use small notches, which produce long stable crack propagation paths that in turn are particularly important in the case of coarse microstructures.

Reliability of timber bridges using nailed plywood box beams

The Nailed Box Beam structural efficiency is directly dependent of the flange-web joint behavior, which determines the partial composition of the section, as the displacement between elements reduces the effective rigidity of the section and changes the stress distribution and the total displacement of the section. This work discusses the use of Nailed Plywood Box Beams in small span timber bridges, focusing on the reliability of the beam element. It is presented the results of tests carried out in 21 full scale Nailed Plywood Box Beams. The analysis of maximum load tests results shows that it presents a normal distribution, permitting the characteristic values calculation as the normal distribution theory specifies. The reliability of those elements was analyzed focusing on a timber bridge design, to estimate the failure probability in function of the load level.

Bone mineralization in Brazilian adolescents: The years of maximum bone mass incorporation

Puberty is the fundamental period for bone mass (BM) acquisition. In this period mineralization is found to increase with levels of high bone formation. The critical years of intense bone anabolism deserve special attention, as adequate gain could minimize fracture risk in later years. The objective of this work was to study bone mineral content (BMC) and bone mineral density (BMD) in male adolescents with age bracket and maturation level. Sixty-one healthy male 10 to 19 year-olds were evaluated for calcium intake, weight, stature, BMI, puberty stage and BMC and BMD in the lumbar spine and femur. BM was measured by bone densitometry (DXA). Calcium intake was calculated by recording 3 days diet. Puberty stage was defined as per Tanner. Descriptive statistics was used with means and standard deviations, linear correlation, and analysis of variance for comparison between age groups, and the Tukey test (p<0.05). Linear correlation was positive and indicated body weight as the main correlation variable with BMD in both studied locations (p<0.01). BMC and BMD increased with age, differences were significant from 14 to 15 years, and when adolescents reached Tanner stage G4. These results showed a pronounced increase in bone mineralization, with the years after 14 to 15 being critical for BM acquisition in Brazilian adolescents.

Anatomical study on domestical fowl (Gallus domesticus) reproductive system

Lately, researchers have taken into consideration studies on birds since they represent an excellent nutritional source. There are several classical descriptions of the male reproductive tract, always aiming at establishing a correlation with shape, testicular size, age and sexual maturity. This study analyzed 50 male Gallus domesticus, 1 to 64 weeks old. The birds were collected with 10 days and then weekly until 24 weeks, following 37, 48, 59 and 64 weeks, and sacrificed by cervical displacement. It was observed the sintopies of testis with the other organs. Further, it was done the testicular measurement and then the statistical analysis by following the model of testis weight variation due to the animal age. Our results showed that the maximum weight of the right and left testes occurred with 167 and 210 days, respectively, what made us infer this species sexual maturity in this period.

Electromyographic evaluation of masseter and anterior temporalis muscles in resting position and during maximum tooth clenching of edentulous patients before and after new complete dentures.

The aim of this study was to assess the electrical activity of the masseter and anterior temporal muscles in patients with severe bone resorption, with complete dentures worn for over ten years, and five months after having new dentures put in place. The RDC questionnaire was applied to twelve asymptomatic patients, before and five months after new dentures were put in place. The electrical activity recordings were made in the mandibular position at rest, and during maximum tooth clenching. The electrical activity of the masseter and anterior temporal muscles in the position at rest presented no statistically significant difference after five months of wearing the new complete dentures. Electrical activity during tooth clenching exhibited a statistically significant reduction only in the right temporal muscle. A period longer than five months of wearing the new complete dentures is required for adaptation and the acquisition of functional capacity.

Produção de Brachiaria brizantha e Panicum maximum com milho e adubação nitrogenada

In places characterized with high temperatures and rain occurrence in great intensity in the summer, but with dry winter, the major limitations for the sustainability of no tillage systems are low production of straw during fall-spring period and the fast decomposition during the rain season. To try to solve the problem, intercropped cultures of grains with forage species has presented reliable results; because offer vegetal covering to the next sowing, giving sustainability to the no tillage system. However, being a recent technology, its needed further studies in different areas involved for this system of production. Thus, this study had the objective 1) to evaluate the production of corn grain at different periods of intercropping with Brachiaria brizantha and Panicum maximum in no tillage system, and 2) aimed to evaluate the performance of forage at different periods of intercropping and the responses to nitrogen fertilization after the harvest of the corn, assessing mass productivity and quality. The experiment was carried out at the Lageado experimental farm, School of Agricultural Sciences, Botucatu campus belonged to São Paulo State University (UNESP) in structuralized Red Nitosol (Afisol). The experimental design was randomized blocks with four replications. The treatments were composed for four systems of no tillage involving corn: 1) single corn; 2) corn with Brachiaria brizantha cv. Marandu intercropped in the sowing; 3) corn with Brachiaria brizantha cv. Marandu intercropped with the fertilization of covering; 4) corn with Panicum maximum cv. Mombaça intercropped in the sowing and 5) corn with Panicum maximum cv. Mombaça intercropped with the fertilization of covering. After the harvest of the corn, it was applied, in equivalent quantities of nitrogen, ammonium nitrate in covering in doses of 0, 30, 60 and 120 kg ha-1, determining the forage mass productivity and quality. The simultaneous tillage of corn with P. maximum cv. Mombaça in the sowing compromises the grain productivity. When sowed in intercropping, B. brizantha presents a fiber concentration reduction and greater TDN concentration during the fall-spring period. Regarding benefits of intercropped cultures seeking to use in systems of production like agriculture-pasture integration, the best intercropping to be utilized is corn sown simultaneously with B. brizantha cv. Marandu.

Analysis of mandibular position using different methods of location.

There has been much discussion regarding the ideal position of the condyle in the mandibular fossa. Although the centric relation position (CR) is used as a reference, some authors do not believe that it is physiologic. Thus, the aim of this study was to evaluate in a group of asymptomatic individuals the position of the condyle in the mandibular fossa at maximum intercuspation (MI), with a occlusal splint and with a Lucia jig between the teeth. It was analyzed by means of magnetic resonance imaging (MRI), transcranial radiography imaging and analysis of horizontal axis of rotation from casts mounted on an articulator. The results showed that even if patients had mandibular displacement in positions of CR, habitual maximum intercuspation and with the occlusal splint, confirmed by means of the analysis of the horizontal axis of rotation, the images showed no statistically significant differences among condylar positions. It can therefore be concluded that the positions analyzed were similar and that transcranial radiography seems to be a reliable method for analyzing condylar position.

A maximum principle for infinite time asymptotically stable impulsive dynamic control systems

We consider an infinite horizon optimal impulsive control problems for which a given cost function is minimized by choosing control strategies driving the state to a point in a given closed set C ∞. We present necessary conditions of optimality in the form of a maximum principle for which the boundary condition of the adjoint variable is such that non-degeneracy due to the fact that the time horizon is infinite is ensured. These conditions are given for conventional systems in a first instance and then for impulsive control problems. They are proved by considering a family of approximating auxiliary interval conventional (without impulses) optimal control problems defined on an increasing sequence of finite time intervals. As far as we know, results of this kind have not been derived previously. © 2010 IFAC.

On the undamped free vibration of a mass interacting with a Hertzian contact stiffness

Three methods are used to determine the natural frequency of undamped free vibration of a mass interacting with a Hertzian contact stiffness. The exact value is determined using the first integral of motion. The harmonic balance method is used on a transformed equation for an approximate solution, and the multiple scales method is used on an approximate equation. The maximum initial displacement avoiding contact loss is also determined, and the corresponding exact natural frequency is also obtained analytically. The methods are evaluated by studying the free vibration of an elastic sphere on a flat rigid surface. © 2011 Elsevier Ltd © 2011 Elsevier Ltd. All rights reserved.

A maximum principle for constrained infinite horizon dynamic control systems

This article presents and discusses a maximum principle for infinite horizon constrained optimal control problems with a cost functional depending on the state at the final time. The main feature of these optimality conditions is that, under reasonably weak assumptions, the multiplier is shown to satisfy a novel transversality condition at infinite time. It is also shown that these conditions can also be obtained for impulsive control problems whose dynamics are given by measure driven differential equations. © 2011 IFAC.