Determination of anaerobic threshold in rats using the lactate minimum test

The break point of the curve of blood lactate vs exercise load has been called anaerobic threshold (AT) and is considered to be an important indicator of endurance exercise capacity in human subjects. There are few studies of AT determination in animals. We describe a protocol for AT determination by the lactate minimum test in rats during swimming exercise. The test is based on the premise that during an incremental exercise test, and after a bout of maximal exercise, blood lactate decreases to a minimum and then increases again. This minimum value indicates the intensity of the AT. Adult male (90 days) Wistar rats adapted to swimming for 2 weeks were used. The initial state of lactic acidosis was obtained by making the animals jump into the water and swim while carrying a load equivalent to 50% of body weight for 6 min (30-s exercise interrupted by a 30-s rest). After a 9-min rest, blood was collected and the incremental swimming test was started. The test consisted of swimming while supporting loads of 4.5, 5.0, 5.5, 6.0 and 7.0% of body weight. Each exercise load lasted 5 min and was followed by a 30-s rest during which blood samples were taken. The blood lactate minimum was determined from a zero-gradient tangent to a spline function fitting the blood lactate vs workload curve. AT was estimated to be 4.95 ± 0.10% of body weight while interpolated blood lactate was 7.17 ± 0.16 mmol/l. These results suggest the application of AT determination in animal studies concerning metabolism during exercise.

Functional and historical determinants of shape in the scapula of Xenarthran mammals: Evolution of a complex morphological structure

The mammalian scapula is a complex morphological structure, composed of two ossification plates that fuse into a single structure. Most studies on morphological differentiation in the scapula have considered it to be a simple, spatially integrated structure, primarily influenced by the important locomotor function presented by this element. We used recently developed geometric morphometric techniques to test and quantify functional and phylogenetic influences on scapular shape variation in fossil and extant xenarthran mammals. The order Xenarthra is well represented in the fossil record and presents a stable phylogenetic hypothesis for its genealogical history. In addition, its species present a large variety of locomotor habits. Our results show that approximately half of the shape variation in the scapula is due to phylogenetic heritage. This is contrary to the view that the scapula is influenced only by functional demands. There are large-scale shape transformations that provide biomechanical adaptation for the several habits (arboreality, terrestriality, and digging), and small scale-shape transformations (mostly related to the coracoid process) that are not influenced by function. A nonlinear relationship between morphometric and phylogenetic distances indicates the presence of a complex mixture of evolutionary processes acting on shape differentiation of the scapula. J. Morphol. 241,251-263, 1999. (C) 1999 Wiley-Liss, Inc.

Caffeine effect on mortality and oviposition in successive generations of Aedes aegypti

OBJETIVO: Experimentos anteriores mostraram que a cafeína bloqueia o desenvolvimento de Aedes aegypti (Diptera, Culicidae) na fase larval, inibindo conseqüentemente a produção de adultos. O objetivo do estudo foi obter dados que pudessem sugerir desenvolvimento de resistência dos mosquitos à cafeína. MÉTODOS: Foi avaliada a produção de adultos em gerações sucessivas, a partir de ovos produzidos na geração anterior e a taxa de oviposição em cada geração, utilizando meios contendo cafeína a 200 e 500 µg/ml e água de torneira proveniente de poço artesiano como controle. Os experimentos foram conduzidos em São José do Rio Preto, entre 2002 e 2005. Nos testes estatísticos foram utilizados a análise exploratória de dados e algoritmos de alisamento. RESULTADOS: Ocorreu redução crescente da produção de adultos, nas duas concentrações, ao longo das gerações, mas apenas no experimento a 200 µg/ml os dados foram estatisticamente significantes. Quanto à oviposição, a análise dos números mostra redução crescente e acentuada na média de ovos por fêmea, no experimento tratado. CONCLUSÕES: Não houve evidência de resistência ao longo das gerações devido ao tratamento com cafeína. Os resultados encontrados podem reforçar a indicação da cafeína como uma alternativa aos principais agentes de controle do Ae. aegypti atualmente usados, contra os quais os mosquitos têm desenvolvido resistência.

The cross-entropy method and its application to minimize the ripple of magnetic levitation forces of a maglev system

This paper explores firstly the potential of a new evolutionary method - the Cross-Entropy (CE) method in solving continuous inverse electromagnetic problems. For this purpose, an adaptive updating formula for the smoothing parameter, some mutation operation, and a new termination criterion are proposed. The proposed CE based metaheuristics is applied to reduce the ripple of the magnetic levitation forces of a prototype Maglev system. The numerical results have shown that the ripple of the magnetic levitation forces of the prototype system is reduced significantly after the design optimization using the proposed algorithm.

SPH simulations of clumps formation by dissipative collision of molecular clouds - I. Non magnetic case

Computer experiments of interstellar cloud collisions were performed with a new smoothed-particle-hydrodynamics (SPH) code. The SPH quantities were calculated by using spatially adaptive smoothing lengths and the SPH fluid equations of motion were solved by means of a hierarchical multiple time-scale leapfrog. Such a combination of methods allows the code to deal with a large range of hydrodynamic quantities. A careful treatment of gas cooling by H, H(2), CO and H II, as well as a heating mechanism by cosmic rays and by H(2) production on grains surface, were also included in the code. The gas model reproduces approximately the typical environment of dark molecular clouds. The experiments were performed by impinging two dynamically identical spherical clouds onto each other with a relative velocity of 10 km s(-1) but with a different impact parameter for each case. Each object has an initial density profile obeying an r(-1)-law with a cutoff radius of 10 pc and with an initial temperature of 20 K. As a main result, cloud-cloud collision triggers fragmentation but in expense of a large amount of energy dissipated, which occurred in the head-on case only. Off-center collision did not allow remnants to fragment along the considered time (similar to 6 Myr). However, it dissipated a considerable amount of orbital energy. Structures as small as 0.1 pc, with densities of similar to 10(4) cm(-3), were observed in the more energetic collision.

Comparação das intensidades correspondentes ao lactato mínimo, limiar de lactato e limiar anaeróbio durante o ciclismo em atletas de endurance

O objetivo deste estudo foi comparar a intensidade de exercício no lactato mínimo (LACmin), com a intensidade correspondente ao limiar de lactato (LL) e limiar anaeróbio (LAn). Participaram do estudo, 11 atletas do sexo masculino (idade, 22,5 + 3,17 anos; altura, 172,3 + 8,2 cm; peso, 66,9 + 8,2kg; e gordura corporal, 9,8 + 3,4%). Os indivíduos foram submetidos, em uma bicicleta eletromagnética (Quinton - Corival 400), a dois testes: 1) exercício contínuo de cargas crescentes - carga inicial de 100W, com incrementos de 25W a cada três min. até a exaustão voluntária; e 2) teste de lactato mínimo - inicialmente os indivíduos pedalaram duas vezes 425W (+ 120%max) durante 30 segundos, com um min. de intervalo, com o objetivo de induzir o acúmulo de lactato. Após oito min. de recuperação passiva, os indivíduos iniciaram um teste contínuo de cargas progressivas, idêntico ao descrito anteriormente. O LL e o LAn foram identificados como sendo o menor valor entre a razão - lactato sanguíneo (mM) / intensidade de exercício (W), e a intensidade correspondente a 3,5mM de lactato sanguíneo, respectivamente. O LACmin foi identificado como sendo a intensidade correspondente a menor concentração de lactato durante o teste de cargas progressivas. Não foi observada diferença significante entre a potência do LL (197,7 + 20,7W) e do LACmin (201,6 + 13,0W), sendo ambas significantemente menores do que do LAn (256,7 + 33,3W). Não foram encontradas também diferenças significantes para o (ml.kg-1.min-1) e a FC (bpm) obtidos no LL (43,2 + 5,01; 152,0 + 13,0) e no LACmin (42,1 + 3,9; 159,0 + 10,0), sendo entretanto significantemente menores do que os obtidos para o LAn (52,2 + 8,2; 174,0 + 13,0, respectivamente). Pode-se concluir que o teste de LACmin, nas condições experimentais deste estudo, pode subestimar a intensidade de MSSLAC (estimada indiretamente pelo LAn), o que concordacom outros estudos que determinaram a MSSLAC diretamente. Assim, são necessários mais estudos que analisem o possível componente tempo-dependente (intensidade inicial) que pode existir no protocolo do LACmin.

O efeito da autocorrelação no planejamento das cartas de controle de x̄ e EWMA

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

Effects of the high-temperature plasma immersion ion-implantation treatment on corrosion behavior of Ti-6Al1-4V

Nitrogen implantation into Ti alloys at higher temperatures improves their mechanical and corrosion resistance properties by forming a thicker nitride layer. In this paper, two different sets of Ti-6Al-4V samples were plasma immersion ion implantation (PIII)-treated using nitrogen plasma, varying the treatment time from 30 to 150 min (800 degrees C) and the process temperature from 400 degrees C to 800 degrees C (t = 60 min). Nanoindentation measurements of the PIII-treated samples at 800 C during 150 min showed the highest hardness value, 24 GPa, which is about four times bigger than untreated sample hardness. The N penetration at these conditions reached approximately 150 nm as analyzed by Auger spectroscopy. on the other hand, the lowest passive current density (3 x 10(-7) A. cm(-2)) was obtained for a PIII-treated sample during 30 min at higher temperature (800 degrees C). The corrosion resistance of this sample is almost the same as for the untreated specimen. Corrosion behavior evidenced that in strong oxidizing media, all PIII-treated samples are more corrosion resistant than the untreated one. PIII processing at higher temperatures promotes smoothing of the sample surface as observed by scanning electron microscopy (SEM). Grazing incidence X-ray diffraction analyses of the untreated samples identified the two typical Ti phases, Ti alpha and Ti beta. After the implantation, Ti2N and TiO2 phases were also detected.

PhotoLin: a program to identify and analyze linear structures in aerial photographs, satellite images and maps

A computer program, PhotoLin, written for an IBM-PC-compatible microcomputer is described which detects linear features in aerial photographs, satellite images and topographic maps. The program accepts images saved to PCX files as input and applies noise correction and smoothing filters and thinning routines. The output consists of a skeleton containing the median lines of linear features which can be represented on a map. The branches of the skeleton can be broken into sections of constant length for which the mean orientations are obtained for the preparation of rose diagrams. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Univariate and bivariate distribution of growth traits in beef buffaloes from Brazil

The aim of this study was to analyze the weight at birth (BW) and adjusted at 205 (W205), 365 (W365) and 550 (W55O) days in beef buffaloes from Brazil, using two approaches: parametric, by normal distribution, and non-parametric, by kernel function, and thus estimating the genetic, environmental and phenotypic correlation among traits. Information of 5,169 animals at birth (BW), 3,792 at 205 days (W205), 3.883 at 365 days (W365) and 1,524 at 550 days of age (W550) were used. The birth weight distribution presented an evident discrepancy in relation to the normal distribution. However, W205, W365 and W550 presented normal distributions. The birth weight presented weak genetic, environmental, and phenotypic associations with the other weight measurements. on the other hand, the weight traits at 205, 365, 550 days of age showed a high genetic correlation.

A well-balanced flow equation for noise removal and edge detection

In this paper, an anisotropic nonlinear diffusion equation for image restoration is presented. The model has two terms: the diffusion and the forcing term. The balance between these terms is made in a selective way, in which boundary points and interior points of the objects that make up the image are treated differently. The optimal smoothing time concept, which allows for finding the ideal stop time for the evolution of the partial differential equation is also proposed. Numerical results show the proposed model's high performance.

Fatores de correção do perímetro escrotal para efeitos de idade e peso ao sobreano de tourinhos nelore

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

Variation in mandible shape in Thrichomys apereoides (Mammalia: Rodentia): Geometric analysis of a complex morphological structure

The model of development and evolution of complex morphological structures conceived by Atchley and Hall in 1991 (Biol. Rev. 66:101-157), which establishes that changes at the macroscopic, morphogenetic level can be statistically detected as variation in skeletal units at distinct scales, was applied in combination with the formalism of geometric morphometrics to study variation in mandible shape among populations of the rodent species Thrichomys apereoides. The thin-plate spline technique produced geometric descriptors of shape derived from anatomical landmarks in the mandible, which we used with graphical and inferential approaches to partition the contribution of global and localized components to the observed differentiation in mandible shape. A major pattern of morphological differentiation in T. apereoides is attributable to localized components of shape at smaller geometric scales associated with specific morphogenetic units of the mandible. On the other hand, a clinal trend of variation is associated primarily with localized components of shape at larger geometric scales. Morphogenetic mechanisms assumed to be operating to produce the observed differentiation in the specific units of the mandible include mesenchymal condensation differentiation, muscle hypertrophy, and tooth growth. Perspectives for the application of models of morphological evolution and geometric morphometrics to morphologically based systematic biology are considered.

Small-angle x-ray scattering study of the structural evolution of the drying of sonogels with the liquid phase exchanged by acetone

The structural evolution on the drying of wet sonogels of silica with the liquid phase exchanged by acetone, obtained from tetraethoxisilane sonohydrolysis, was studied in situ by small-angle x-ray scattering (SAXS). The periods associated to the structural evolution as determined by SAXS are in agreement with those classical ones established on basis of the features of the evaporation rate of the liquid phase in the obtaining of xerogels. The wet gel can be described as formed by primary particles (microclusters), with characteristic length a ∼ 0.67 nm and surface which is fractal, linking together to form mass fractal structures with mass fractal dimension D=2.24 in a length scale ξ∼6.7 nm. As the network collapses while the liquid/vapor meniscus is kept out of the gel volume, the mass fractal structure becomes more compacted by increasing D and decreasing ξ, with smoothing of the fractal surface of the microclusters. The time evolution of the density of the wet gels was evaluated exclusively from the SAXS parameters ξ, D, and a. The final dried acetone-exchanged gel presents Porod's inhomogeneity length of about 2.8 nm and apparently exhibits an interesting singularity D →3, as determined by the mass fractal modeling used to fit the SAXS intensity data for the obtaining of the parameters ξ and D.

Using cubic splines to mitigate systematic errors in GPS relative positioning

Systematic errors can have a significant effect on GPS observable. In medium and long baselines the major systematic error source are the ionosphere and troposphere refraction and the GPS satellites orbit errors. But, in short baselines, the multipath is more relevant. These errors degrade the accuracy of the positioning accomplished by GPS. So, this is a critical problem for high precision GPS positioning applications. Recently, a method has been suggested to mitigate these errors: the semiparametric model and the penalised least squares technique. It uses a natural cubic spline to model the errors as a function which varies smoothly in time. The systematic errors functions, ambiguities and station coordinates, are estimated simultaneously. As a result, the ambiguities and the station coordinates are estimated with better reliability and accuracy than the conventional least square method.