Neural extrapolation of motion for a ball rolling down an inclined plane

It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions) and slope (30°, 45° or 60°). In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1). However, even when participants punched an imaginary moving ball (Experiment 2) or drew in air the imaginary trajectory (Experiment 3), they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion

Coherence of structural visual cues and pictorial gravity paves the way for interceptive actions

Dealing with upside-down objects is difficult and takes time. Among the cues that are critical for defining object orientation, the visible influence of gravity on the object's motion has received limited attention. Here, we manipulated the alignment of visible gravity and structural visual cues between each other and relative to the orientation of the observer and physical gravity. Participants pressed a button triggering a hitter to intercept a target accelerated by a virtual gravity. A factorial design assessed the effects of scene orientation (normal or inverted) and target gravity (normal or inverted). We found that interception was significantly more successful when scene direction was concordant with target gravity direction, irrespective of whether both were upright or inverted. This was so independent of the hitter type and when performance feedback to the participants was either available (Experiment 1) or unavailable (Experiment 2). These results show that the combined influence of visible gravity and structural visual cues can outweigh both physical gravity and viewer-centered cues, leading to rely instead on the congruence of the apparent physical forces acting on people and objects in the scene

Perceptual judgments of duration of parabolic motions

In a 2-alternative forced-choice protocol, observers judged the duration of ball motions shown on an immersive virtual-reality display as approaching in the sagittal plane along parabolic trajectories compatible with Earth gravity effects. In different trials, the ball shifted along the parabolas with one of three different laws of motion: constant tangential velocity, constant vertical velocity, or gravitational acceleration. Only the latter motion was fully consistent with Newton's laws in the Earth gravitational field, whereas the motions with constant velocity profiles obeyed the spatio-temporal constraint of parabolic paths dictated by gravity but violated the kinematic constraints. We found that the discrimination of duration was accurate and precise for all types of motions, but the discrimination for the trajectories at constant tangential velocity was slightly but significantly more precise than that for the trajectories at gravitational acceleration or constant vertical velocity. The results are compatible with a heuristic internal representation of gravity effects that can be engaged when viewing projectiles shifting along parabolic paths compatible with Earth gravity, irrespective of the specific kinematics. Opportunistic use of a moving frame attached to the target may favour visual tracking of targets with constant tangential velocity, accounting for the slightly superior duration discrimination

Genetic variability of garlic accessions as revealed by agro-morphological traits evaluated under different environments.

The cultivated garlic (Allium sativum L.) displays a wide phenotypic diversity, which is derived from natural mutations and phenotypic plasticity, due to dependence on soil type, moisture, latitude, altitude and cultural practices, leading to a large number of cultivars. This study aimed to evaluate the genetic variability shown by 63 garlic accessions belonging to Instituto Agronômico de Campinas and the Escola Superior de Agricultura ?Luiz de Queiroz? germplasm collections. We evaluated ten quantitative characters in experimental trials conducted under two localities of the State of São Paulo: Monte Alegre do Sul and Piracicaba, during the agricultural year of 2007, in a randomized blocks design with five replications. The Mahalanobis distance was used to measure genetic dissimilarities. The UPGMA method and Tocher?s method were used as clustering procedures. Results indicated significant variation among accessions (P < 0.01) for all evaluated characters, except for the percentage of secondary bulb growth in MAS, indicating the existence of genetic variation for bulb production, and germplasm evaluation considering different environments is more reliable for the characterization of the genotypic variability among garlic accessions, since it diminishes the environmental effects in the clustering of genotypes

Diversidade genética entre plantas sexuais de Panicum maximum Jacq. acessada por marcadores RAPD.

O objetivo deste trabalho foi avaliar a diversidade genética entre plantas sexuais tetraploides de Panicum maximum do banco de germoplasma da Embrapa Gado de Corte, utilizando a técnica de polimorfismos de DNA amplificados ao acaso (RAPD). Quatroze plantas foram avaliadas com 17 primers. A similaridade genética foi calculada usando o coeficiente de Jaccard e o agrupamento foi feito pelo método de médias aritméticas dos pares de grupos não-balanceados (UPGMA) com base nas dissimilaridades. Uma análise de bootstrap foi feita para avaliar a consistência dos grupos formados. Um total de 145 bandas de DNA foi obtido, sendo que 128 (~88,3%) delas foram polimórficas entre as plantas estudadas. Os valores de similaridade variaram de 0,34 a 0,69. Quatro grupos foram formados e as plantas S16 e S13 não foram agrupadas com as plantas restantes, apresentando maior divergência genética. Os resultados mostram moderada diversidade genética entre as 14 plantas sexuais tetraploides de P. maximum estudadas. Os resultados obtidos podem subsidiar a escolha de progenitores para cruzamentos visando melhoramento genético da espécie.bitstream/item/71880/1/BP30.pd

Differences and similarities of postprandial lipemia in rodents and humans

The rat has been a mainstay of physiological and metabolic research, and more recently mice. This study aimed at characterizing the postprandial triglyceride profile of two members of the Muridae family: the Wistar rats (Rattus norvegicus albinus) and C57BL/6 mice (Mus musculus) plus comparing them to the profile obtained in humans. Thirty-one male and twelve female Wistar rats, ten C57BL/6 male and nine female mice received a liquid meal containing fat (17%), protein (4%) and carbohydrates (4%), providing 2 g fat/Kg. Thirty-one men and twenty-nine women received a standardized liquid meal containing fat (25%), dextromaltose (55%), protein (14%), and vitamins and minerals (6%), and providing 40 g of fat per square meter of body surface. Serial blood samples were collected at 2, 4, 6, 8 and 10 h after the ingestion in rats, at 1, 2, 3, 4, 5 and 6 h in mice and in humans at 2, 4, 6 and 8 h. Wilcoxon and Mann-Whitney tests were used. The triglyceride responses were evaluated after the oral fat loads. Fasting and postprandial triglyceridemia were determined sequentially in blood sample. AUC, AUIC, AR, RR and late peaks were determined. Rats are prone to respond in a pro-atherogenic manner. The responses in mice were closer to the ones in healthy men. This study presents striking differences in postprandial triglycerides patterns between rats and mice not correlated to baseline triglycerides, the animal baseline body weight or fat load in all animal groups.101CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão temNão te

Dysgraphia in patients with primary lateral sclerosis: a speech-based rehearsal deficit?

The present study aims to demonstrate that errors when writing are more common than expected in patients affected by primary lateral sclerosis (PLS) with severe dysarthria or complete mutism, independent of spasticity. Sixteen patients meeting Pringle's et al. [34] criteria for PLS underwent standard neuropsychological tasks and evaluation of writing. We assessed writing abilities in spelling through dictation in which a set of words, non-words and short phrases were presented orally and by composing words using a set of preformed letters. Finally, a written copying task was performed with the same words. Relative to controls, PLS patients made a greater number of spelling errors in all writing conditions, but not in copy task. The error types included: omissions, transpositions, insertions and letter substitutions. These were equally distributed on the writing task and the composition of words with a set of preformed letters. This pattern of performance is consistent with a spelling impairment. The results are consistent with the concept that written production is critically dependent on the subvocal articulatory mechanism of rehearsal, perhaps at the level of retaining the sequence of graphemes in a graphemic buffer. In PLS patients a disturbance in rehearsal opportunity may affect the correct sequencing/assembly of an orthographic representation in the written process

Synchronization to a bouncing ball with a realistic motion trajectory

Daily music experience involves synchronizing movements in time with a perceived periodic beat. It has been established for over a century that beat synchronization is less stable for the visual than for the auditory modality. This auditory advantage of beat synchronization gives rise to the hypotheses that the neural and evolutionary mechanisms underlying beat synchronization are modality-specific. Here, however, we found that synchronization to a periodically bouncing ball with a realistic motion trajectory was not less stable than synchronization to an auditory metronome. This finding challenges the auditory advantage of beat synchronization, and has important implications for the understanding of the biological substrates of beat synchronization

Morphological diversity of cassava accessions of the south-central mesoregion of the State of Mato Grosso, Brazil.

Genetic variability of cassava (Manihot esculenta Crantz) in Brazil is wide, being this the result of natural and cultural selection during pre- and post-domestication of the species in different environments. Given the number of species of the genus found in the region (38 of a total of 98 species), the central region of Brazil was defined as the primary center of cassava diversity. Therefore, genetic diversity characterization of cassava accessions is fundamental, both for farmers and for plant breeders, because it allows the organization of genetic resources and better utilization of available genetic diversity. This research aims to assess genetic divergence of cassava accessions from the south-central region of the State of Mato Grosso, based on multi-categorical morphological traits. For this purpose, 38 qualitative and quantitative morphological descriptors were used. Genetic diversity was expressed by the genetic similarity index, with subsequent clustering of accessions by the modified Tocher?s procedure and UPGMA. Of 38 descriptors, only growth habit of stem showed no variability. Tocher and UPGMA methods were efficient and corroborated on group composition. Both methods were able to group accessions of different localities in distinct group consistency

Avaliação de acessos de mandioca quanto ao teor de ácido cianídrico em raízes frescas.

A mandioca é considerada a espécie cianogênica mais importante do Brasil, sendo classificada pela taxonomia popular em bravas e mansas dependendo do teor de ácido cianídrico encontrado nas raízes. Este componente varia substancialmente em razão da variedade, mas pode variar também, em menor escala, em relação as condições de cultivo, época de colheita e condições ambientais. As mandiocas consideradas bravas têm sabor amargo, e elevado teor de glicosídeos cianogênicos, e podem ser consumidas após o processamento. As consideradas mansas não têm sabor amargo, contêm baixo teor de glicosídeos cianogênicos e podem ser consumidas com ou sem qualquer processamento. Com a finalidade de colaborar na seleção de novas cultivares de mandioca para o consumo ?in natura?, seja na alimentação animal ou humana, esta pesquisa objetivou analisar o teor de ácido cianídrico de 159 acessos de mandioca, pertencentes à coleção de mandioca da Embrapa Agrosilvipastoril e Unemat/Cáceres. As amostras de raiz foram colhidas aos 12 meses após o plantio. Para determinar o teor de ácido cianídrico livre foi utilizada a metodologia de cromatografia iônica proposta por Caliamannis et al. (2000) modificada. Os padrões para classificar o acesso de mandioca como mansa ou brava seguiu o proposto por Bolhuis (1954), que classifica mandiocas mansas, com teor abaixo de 100 mg kg-1 de ácido cianídrico e bravas, com teor maior que 100 mg kg-1. Os teores de ácido cianídrico dos acessos variaram de 2.03 mg kg-1 para o acesso UNRO-15 a 487,26 mg kg-1, registrado no acesso ENJA-43. Dos acessos avaliados, 52% apresentaram teor de ácido cianídrico abaixo de 100 mg kg-1, sendo consideradas mansas e recomendadas para o consumo ?in natura?. Já os acessos considerados como mandioca brava somaram 48%, podendo estes ser destinados à indústria, uma vez que o processamento da raiz baseia-se na dissolução e volatilização dos princípios tóxicos. A identificação de variedades de mandioca com baixos teores HCN em raízes frescas é importante para o respaldo e segurança nas recomendações de cultivares destinada a alimentação humana ou animal. Por isso, destaca-se a relevância de programas de melhoramento genético que visam à identificação e seleção de novas variedades de mandioca para consumo na forma de raízes frescas com baixos teores de ácido cianídrico