194 research outputs found

    The Foveal Confluence in Human Visual Cortex

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    The human visual system devotes a significant proportion of its resources to a very small part of the visual field, the fovea. Foveal vision is crucial for natural behavior and many tasks in daily life such as reading or fine motor control. Despite its significant size, this part of cortex is rarely investigated and the limited data have resulted in competing models of the layout of the foveal confluence in primate species. Specifically, how V2 and V3 converge at the central fovea is the subject of debate in primates and has remained “terra incognita” in humans. Using high-resolution fMRI (1.2 × 1.2 × 1.2 mm3) and carefully designed visual stimuli, we sought to accurately map the human foveal confluence and hence disambiguate the competing theories. We find that V1, V2, and V3 are separable right into the center of the foveal confluence, and V1 ends as a rounded wedge with an affine mapping of the foveal singularity. The adjacent V2 and, in contrast to current concepts from macaque monkey, also V3 maps form continuous bands (∼5 mm wide) around the tip of V1. This mapping results in a highly anisotropic representation of the visual field in these areas. Unexpectedly, for the centermost 0.75°, the cortical representations for both V2 and V3 are larger than that of V1, indicating that more neuronal processing power is dedicated to second-level analysis in this small but important part of the visual field

    Visual art inspired by the collective feeding behavior of sand-bubbler crabs

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    Sand--bubblers are crabs of the genera Dotilla and Scopimera which are known to produce remarkable patterns and structures at tropical beaches. From these pattern-making abilities, we may draw inspiration for digital visual art. A simple mathematical model is proposed and an algorithm is designed that may create such sand-bubbler patterns artificially. In addition, design parameters to modify the patterns are identified and analyzed by computational aesthetic measures. Finally, an extension of the algorithm is discussed that may enable controlling and guiding generative evolution of the art-making process

    Preference for fractal-scaling properties across synthetic noise images and artworks

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    A large number of studies support the notion that synthetic images within a certain intermediate fractal-scaling range possess an intrinsic esthetic value. Interestingly, the fractal-scaling properties that define this intermediate range have also been found to characterize a vast collection of representational, abstract, and graphic art. While some have argued that these statistic properties only serve to maximize the visibility of the artworks' spatial structure, others argue that they are intrinsically tied to the artworks' esthetic appeal. In this study, we bring together these two threads of research and make a direct comparison between visual preference for varying fractal-scaling characteristics in both synthetic images and artworks. Across two studies, viewers ranked and rated sets of synthetic noise images and artworks that systematically varied in fractal dimension for liking, pleasantness, complexity, and interestingness. We analyzed both average and individual patterns of preference between the two image classes. Average preference peaked for intermediate fractal dimension values for both categories, but individual patterns of preferences for both high and low values also emerged. Correlational analyses indicated that individual preferences between the two image classes remained moderately consistent and were improved when the fractal dimensions between synthetic images and artworks were more closely matched. Overall, these findings further support the role of fractal-scaling statistics both as a key determinant of an object's esthetic value and as a valuable predictor of individual differences in esthetic preference

    Orion Handling Qualities During ISS Rendezvous and Docking

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    The Orion spacecraft was designed to rendezvous with multiple vehicles in low earth orbit (LEO) and beyond. To perform the required rendezvous and docking task, Orion must provide enough control authority to perform coarse translational maneuvers while maintaining precision to perform the delicate docking corrections. While Orion has autonomous docking capabilities, it is expected that final approach and docking operations with the International Space Station (ISS) will initially be performed in a manual mode. A series of evaluations was conducted by NASA and Lockheed Martin at the Johnson Space Center to determine the handling qualities (HQ) of the Orion spacecraft during different docking and rendezvous conditions using the Cooper-Harper scale. This paper will address the specifics of the handling qualities methodology, vehicle configuration, scenarios flown, data collection tools, and subject ratings and comments. The initial Orion HQ assessment examined Orion docking to the ISS. This scenario demonstrates the Translational Hand Controller (THC) handling qualities of Orion. During this initial assessment, two different scenarios were evaluated. The first was a nominal docking approach to a stable ISS, with Orion initializing with relative position dispersions and a closing rate of approximately 0.1 ft/sec. The second docking scenario was identical to the first, except the attitude motion of the ISS was modeled to simulate a stress case ( 1 degree deadband per axis and 0.01 deg/sec rate deadband per axis). For both scenarios, subjects started each run on final approach at a docking port-to-port range of 20 ft. Subjects used the THC in pulse mode with cues from the docking camera image, window views, and range and range rate data displayed on the Orion display units. As in the actual design, the attitude of the Orion vehicle was held by the automated flight control system at 0.5 degree deadband per axis. Several error sources were modeled including Reaction Control System (RCS) jet angular and position misalignment, RCS thrust magnitude uncertainty, RCS jet force direction uncertainty due to self plume impingement, and Orion center of mass uncertainty

    Political Marketing Activity in Simultaneous Regional Elections 2015

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    Regional head election system was change in 2015. It has impact on political marketing strategy to all stake holders, such as political party and candidatures.The purposes of this research is to analyzeashifting ofpolitical marketing issueson regional election 2015. The research approach uses the mix method with the type of sequential explanatory. The subjects of this research are the candidates, election successful teams or supporting team, and young voters. Location of research based on cluster system district and sub district in Bandung, Cianjur, Magelang, Sleman, and Medan. The data are collected through techniques of questionnaires to young voters; interview to candidates, election successful teams and young voters, as well as the documentation of media and data on Regional General Elections Commission (KPUD). There are also triangular data techniqueinterviews with the General Elections Commission (KPU), the community and supporting team, and documentation and questionnaire form. The result shows that the system of political marketing has already started shifting from product, promotion, price, place, and people known as the 5Ps from mostly dominated by Political Partyinto the role of PEOPLE as candidature in influensing the voters. The Result also tells that shifting from using convetional media into almost using digital media was powerfull

    The effect of image fractal properties and its interaction with visual discomfort on gait kinematics

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    Exposure to images of urban environments affords higher cognitive processing demands than exposure to images of nature scenes; an effect potentially related to differences in low-level image statistics such as fractals. The aim of the current study was to investigate whether the fractal dimensions of an abstract scene affect cognitive processing demands, using gait kinematics as a measure of cognitive demand. Participants (n = 40) were asked to walk towards different types of synthetic images which were parametrically varied in their fractal dimensions. At the end of each walk, participants rated each image for its visual discomfort (n = 20) or for its likability (n = 20) as potential confounding factors. Fractal dimensions were predictors of walking speed. Moreover, the interaction between fractal dimensions and subjective visual discomfort but not liking predicted velocity. Overall, these data suggest that fractal dimensions indeed contribute to environmentally induced cognitive processing demands

    Nature in motion: The tuning of the visual system to the spatiotemporal properties of natural scenes

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    Natural scenes contain several statistical regularities despite their superficially diverse appearances (e.g., mountains, rainforests, deserts). First, they exhibit a unique distribution of luminance intensities decreasing across spatial frequency, known as the 1/fα amplitude spectrum (α ≈ 1). Additionally, natural scenes share consistent geometric properties, comprising similar densities of structure across multiple scales—a property classifying them as fractal (e.g., how the branching patterns of rivers and trees appear similar irrespective of scale). These two properties are intimately related and correlate strongly in natural scenes. However, research using thresholded noise images suggests that spatially, the human visual system is preferentially tuned to natural scene structure more so than 1/fα spectra. It is currently unclear whether this dependency on natural geometry extends to the temporal domain.We used a psychophysics task to measure discrimination sensitivity toward two types of synthetic noise movies: gray scale and thresholded (N = 60). Each movie type shared the same geometric properties (measured fractal D), but substantially differing spectral properties (measured α). In both space and time, we observe a characteristic dependency on stimulus structure across movie types, with sensitivity peaking for stimuli with natural geometry despite having altered 1/fα spectra. Although only measured behaviorally, our findings may developed to be sensitive to the most stable signal in our natural environment—structure (e.g., the structural properties of a tree are consistent from morning to night despite illumination changes across time points

    Andean grain crop introduction to the Brazilian savannah.

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    Agricultural history of the Brazilian savannah dates back 150 years, beginning with extensive cattle ranching on native grassland, eventually developing into a rice-pasture system, followed by today’s modern grain production on 10 million ha. For the past 20 years the cropping system has been soybean and maize in the rainy season, with little agricultural activity during the long dry season. A recent trend toward growing crops as a source of mulch has been limited to a few species of two botanical families: Gramineae such as maize, millet, and sorghum; and Leguminosae such as soybean. Such highly specialized monocrop systems, which are becoming common in Brazil, threaten the sustainability of the region, because of increased pests, diseases and weeds problems, loss of soil organic matter content due to excessive soil preparation, nutrient loss, soil compaction and erosion, increased production cost due to excessive/unbalanced use of fertilizers and pesticides, yield reduction, and negative environmental impacts. Introduction of new crops is essential to improve the sustainability of the system, serving as break-crops to increase soil fertility and provide additional income to farmers. The selection criteria for new species are drought resistance, rapid growth, nutrient improvement, and diversified uses. Two species that meet these characteristics are the Andean grain crops quinoa (Chenopodium quinoa Willd.) and amaranth (Amaranthus spp.). They are characterized by a high quality protein and a high vitamin and mineral content. In the low-altitude tropical savannah, locally selected genotypes of quinoa, originating from hybrid populations in Cambridge, England, have been evaluated in Brazil in Planaltina, DF (1000 masl; 15o S latitude) and in Rio Verde, GO (700 masl; 18o S latitude) in the winter dry season from May to September, following the main crop. Yields were nearly 7.0 t dry matter/ha and 3.0 t seed/ha, with a growth period varying between 90 and 130 days. In preliminary yield trials amaranth accessions gave similar results. Further research to determine improved production practices for optimal, sustainable cultivation of quinoa and amaranth, and to evaluate their market potential, is needed. It is expected that these novel crops can contribute to the development of the Brazilian savannah to benefit farmers and the environment, making this important ecological region less prone to degradation
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