441 research outputs found
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
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
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
Realization of the farad from the dc quantum Hall effect with digitally-assisted impedance bridges
A new traceability chain for the derivation of the farad from dc quantum Hall
effect has been implemented at INRIM. Main components of the chain are two new
coaxial transformer bridges: a resistance ratio bridge, and a quadrature
bridge, both operating at 1541 Hz. The bridges are energized and controlled
with a polyphase direct-digital-synthesizer, which permits to achieve both main
and auxiliary equilibria in an automated way; the bridges and do not include
any variable inductive divider or variable impedance box. The relative
uncertainty in the realization of the farad, at the level of 1000 pF, is
estimated to be 64E-9. A first verification of the realization is given by a
comparison with the maintained national capacitance standard, where an
agreement between measurements within their relative combined uncertainty of
420E-9 is obtained.Comment: 15 pages, 11 figures, 3 table
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
Strength of Protection for Geographical Indications: Promotion Incentives and Welfare Effects
We address the question of how the strength of protection for geographical indications (GIs) affects the GI industry\u27s promotion incentives, equilibrium market outcomes, and the distribution of welfare. Geographical indication producers engage in informative advertising by associating their true quality premium (relative to a substitute product) with a specific label emphasizing the GI\u27s geographic origin. The extent to which the names/words of the GI label can be used and/or imitated by competing products—which depends on the strength of GI protection—determines how informative the GI promotion messages can be. Consumers’ heterogeneous preferences (vis-à-vis the GI quality premium) are modeled in a vertically differentiated framework. Both the GI industry and the substitute product industry are assumed to be competitive (with free entry). The model is calibrated and solved for alternative parameter values. Results show that producers of the GI and of the lower-quality substitute good have divergent interests: GI producers are better off with full protection, whereas the substitute good\u27s producers prefer intermediate levels of protection (but they never prefer zero protection because they benefit indirectly if the GI producers’ incentives to promote are preserved). For consumers and aggregate welfare, the preferred level of protection depends on the model\u27s parameters, with an intermediate level of protection being optimal in many circumstances
Incorporating Prediction in Models for Two-Dimensional Smooth Pursuit
A predictive component can contribute to the command signal for smooth pursuit. This is readily demonstrated by the fact that low frequency sinusoidal target motion can be tracked with zero time delay or even with a small lead. The objective of this study was to characterize the predictive contributions to pursuit tracking more precisely by developing analytical models for predictive smooth pursuit. Subjects tracked a small target moving in two dimensions. In the simplest case, the periodic target motion was composed of the sums of two sinusoidal motions (SS), along both the horizontal and the vertical axes. Motions following the same or similar paths, but having a richer spectral composition, were produced by having the target follow the same path but at a constant speed (CS), and by combining the horizontal SS velocity with the vertical CS velocity and vice versa. Several different quantitative models were evaluated. The predictive contribution to the eye tracking command signal could be modeled as a low-pass filtered target acceleration signal with a time delay. This predictive signal, when combined with retinal image velocity at the same time delay, as in classical models for the initiation of pursuit, gave a good fit to the data. The weighting of the predictive acceleration component was different in different experimental conditions, being largest when target motion was simplest, following the SS velocity profiles
Broad-spectrum antibiotics disrupt homeostatic efferocytosis
The clearance of apoptotic cells, termed efferocytosis, is essential for tissue homeostasisand prevention of autoimmunity1. Although past studies have elucidated local molecular signals that regulate homeostatic efferocytosis in a tissue2,3, whether signals arising distally also regulate homeostatic efferocytosis remains elusive. Here, we show that large peritoneal macrophages (LPMs) display impairs efferocytosis in broad-spectrum antibiotics (ABX)-treated, vancomycin treated, and germ-free mice in vivo, all of which have a depleted gut microbiota. Mechanistically, the microbiota-derived short-chain fatty acid butyrate directly boosts efferocytosis efficiency and capacity in mouse and human macrophages, and rescues ABX-induced LPM efferocytosis defects in vivo. Bulk mRNA sequencing of butyrate-treated macrophages in vitro and single cell mRNA sequencing of LPMs isolated from ABX-treated and butyrate-rescued mice reveals regulation of efferocytosis-supportive transcriptional programs. Specifically, we find that the efferocytosis receptor T-cell immunoglobulin and mucin domain containing 4 (TIM-4, Timd4) is downregulated in LPMs of ABX-treated mice but rescued by oral butyrate. We show that TIM-4 is required for the butyrate-induced enhancement of LPM efferocytosis capacity and that LPM efferocytosis is impaired beyond withdrawal of ABX. ABX-treated mice exhibit significantly worse disease in a mouse model of lupus. Our results demonstrate that homeostatic efferocytosis relies on distal metabolic signals and suggest that defective homeostatic efferocytosis may explain the link between ABX use and inflammatory disease4–7
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