813 resultados para eye tracking
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The ability to appropriately interact with the environment is crucial to an organism’s survival. The establishment of functional sensory systems, such as the bristles and eyes in Drosophila, is a critical event during the development of the organism. The transcription factor D Pax2 is involved in the differentiation of the shaft and glial cells in the developing bristle (Kavaler et al., Dev, 126:2261-2272, 1999) and of the cone and primary pigment cells in the developing eye (Fu and Noll, Genes Dev, 11:389-405, 1997). How D-Pax2 contributes to distinct differentiative pathways in different cell types is not known. Recent work by Anna Czechowski and Katherine Harmon (personal communication) identified a mutation in the D-Pax2 gene that introduced a stop codon at the end of exon 9, effectively truncating the protein. This mutation affects bristle, but not eye, development. We thus suspected regions after exon 9 are required for D-Pax2 function only in the bristles and may also be associated with alternative splicing of the D Pax2 transcript. We plan to assess the role of the carboxy terminal region of the protein by establishing transgenic lines bearing rescue constructs of D-Pax2 with either the complete coding sequence or with deletions of specific exons. To date, we have generated the first rescue construct bearing the complete coding region of the gene driven by a 3 KB upstream regulatory region of D-Pax2 and are currently generating transgenic fly lines with this construct.
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In the last years the number of industrial applications for Augmented Reality (AR) and Virtual Reality (VR) environments has significantly increased. Optical tracking systems are an important component of AR/VR environments. In this work, a low cost optical tracking system with adequate attributes for professional use is proposed. The system works in infrared spectral region to reduce optical noise. A highspeed camera, equipped with daylight blocking filter and infrared flash strobes, transfers uncompressed grayscale images to a regular PC, where image pre-processing software and the PTrack tracking algorithm recognize a set of retro-reflective markers and extract its 3D position and orientation. Included in this work is a comprehensive research on image pre-processing and tracking algorithms. A testbed was built to perform accuracy and precision tests. Results show that the system reaches accuracy and precision levels slightly worse than but still comparable to professional systems. Due to its modularity, the system can be expanded by using several one-camera tracking modules linked by a sensor fusion algorithm, in order to obtain a larger working range. A setup with two modules was built and tested, resulting in performance similar to the stand-alone configuration.
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O Brasil se tornou nos últimos anos uma importante economia no cenário global. O país sempre foi visto basicamente como um exportador de commodities; no entanto, devido ao crescimento de investimentos e ao desenvolvimento de diversos setores econômicos, essa imagem mudou e está em processo de reconstrução. As empresas para poderem se diferenciarem e ganharem competitividade, precisam entender profundamente como consumidores percebem e avaliam os produtos brasileiros atualmente. É de extrema importância para o Brasil entender o potencial competitivo para posicionar-se corretamente contra as nações desenvolvidas e altamente industrializadas, bem como contra as gigantes economias emergentes como Rússia, China e Índia. Este estudo explora como um grupo de respondentes italianos avaliam a categoria de cosméticos brasileiros. Foi conduzida uma pesquisa exploratória com o objetivo de identificar dentre quarto categorias diferentes de produtos qual seria analisada em detalhe posteriormente por meio de entrevistas em profundidade. Das 4 categorias diferentes de produtos (vestuário, cosméticos, frutas frescas e carnes) foi selecionada a categoria cosméticos que obteve a menor avaliação geral no estudo exploratório. Após a escolha da categoria a ser analisada, uma pesquisa qualitativa com 7 entrevistas em profundidade com consumidores italianos residentes no Brasil foram realizadas. Das pesquisas realizadas são obtidas as percepções de um grupo de consumidores sobre os atributos e associações psicológicas sobre a categoria de cosméticos brasileiros. A análise será conduzida utilizando 3 componentes para explicar a atitude de consumo: a cognitiva, a conativa e a emocional. Deste modo, os resultados e conclusões são apresentados e explorados. Ademais, um mapa psicológico das atitudes sobre a categoria analisada perante o público estudado será desenvolvido, com o objetivo de pontuar suas forças e fraquezas. Desta análise final será possível ter uma visão ampla das características, bem como dos pontos críticos que precisam ser melhorados no futuro para que o Brasil seja uma nação competitiva na indústria de cosméticos e também algumas questões que podem ser estendidas a outros setores da economia brasileira.
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Indexing is a passive investment strategy in which the investor weights bis portfolio to match the performance of a broad-based indexo Since severaI studies showed that indexed portfolios have consistently outperformed active management strategies over the last decades, an increasing number of investors has become interested in indexing portfolios IateIy. Brazilian financiaI institutions do not offer indexed portfolios to their clients at this point in time. In this work we propose the use of indexed portfolios to track the performance oftwo ofthe most important Brazilian stock indexes: the mOVESPA and the FGVIOO. We test the tracking performance of our modeI by a historical simulation. We applied several statistical tests to the data to verify how many stocks should be used to controI the portfolio tracking error within user specified bounds.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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A method of determining spectral parameters p (slope of the phase PSD) and T (phase PSD at 1 Hz) and hence tracking error variance in a GPS receiver PLL from just amplitude and phase scintillation indices and an estimated value of the Fresnel frequency has been previously presented. Here this method is validated using 50 Hz GPS phase and amplitude data from high latitude receivers in northern Norway and Svalbard. This has been done both using (1) a Fresnel frequency estimated using the amplitude PSD (in order to check the accuracy of the method) and (2) a constant assumed value of Fresnel frequency for the data set, convenient for the situation when contemporaneous phase PSDs are not available. Both of the spectral parameters (p, T) calculated using this method are in quite good agreement with those obtained by direct measurements of the phase spectrum as are tracking jitter variances determined for GPS receiver PLLs using these values. For the Svalbard data set, a significant difference in the scintillation level observed on the paths from different satellites received simultaneously was noted. Then, it is shown that the accuracy of relative GPS positioning can be improved by use of the tracking jitter variance in weighting the measurements from each satellite used in the positioning estimation. This has significant advantages for scintillation mitigation, particularly since the method can be accomplished utilizing only time domain measurements thus obviating the need for the phase PSDs in order to extract the spectral parameters required for tracking jitter determination.
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Importance of the field: The use of topical agents poses unique and challenging hurdles for drug delivery. Topical steroids effectively control ocular inflammation, but are associated with the well-recognized dilemma of patient compliance. Although administration of topical antimicrobials as prophylaxis is acceptable among ophthalmologists, this common practice has no sound evidence base Developing a new antimicrobial agent or delivery strategy with enhanced penetration by considering the anatomical and physiological constraints exerted by the barriers of the eye is not a commonly perceived strategy. Exploiting the permeability of the sclera, subconjunctival routes may offer a promising alternative for enhanced drug delivery and tissue targeting.Area covered in this review: Ocular drug delivery strategies were reviewed for ocular inflammation and infections clinically adopted for newer class of antimicrobials, which use a multipronged approach to limit risks of endophthalmitis.What the reader will gain: The analysis substantiates a new transscleral drug delivery therapeutic approach for cataract surgery.Take home message: A new anti-inflammatory and anti-infective paradigm that frees the patient from the nuisance of topical therapeutics is introduced, opening a large investigative avenue for future improved therapies.
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This article aims to analyse the introduction of environmental issues in the context of the production function, which has been referred to as the organisational area to lead corporate environmental management. With that purpose, the theoretical references for corporate environmental management and the necessary alterations in production function have been organised to include environmental aspects, especially in terms of product and process development, quality management, and logistics. Considering that this research field still lacks empirical evidence for Brazilian companies, four case studies were conducted using companies located in the country. The environmental management maturity level of those companies tends to follow the rate with which the environmental issue is introduced in production sub-areas, especially in the product development process. However, in most cases we found that the companies had difficulties in structuring the insertion of the environmental dimension in logistics. The final notes point out the distance observed between what is recommended by international literature and the reality of Brazilian companies in the challenge of making the production function environmentally friendly.
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The problem of signal tracking, in the presence of a disturbance signal in the plant, is solved using a zero-variation methodology. A state feedback controller is designed in order to minimise the H-2-norm of the closed-loop system, such that the effect of the disturbance is attenuated. Then, a state estimator is designed and the modification of the zeros is used to minimise the H-infinity-norm from the reference input signal to the error signal. The error is taken to be the difference between the reference and the output signals, thereby making it a tracking problem. The design is formulated in a linear matrix inequality framework, such that the optimal solution of the stated control problem is obtained. Practical examples illustrate the effectiveness of the proposed method.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Purpose: To investigate the dynamics of ocular eyelid movements in newborn infants and preschool-age children.Methods: Fifty newborn infants and 200 preschool children aged 4-6 years were examined. Images of each child, with his or her eyes in the primary eye position looking at an object placed at the child's height, were recorded with a digital videocamera for 3 mins. Complete and incomplete blink rates, opening, closing and complete blink times were calculated.Results: Newborn infants presented a lower number of incomplete movements than preschool children. The complete blink rate was lower in newborn infants (6.2 blinks/min) than in preschool children (8.0 blinks/minute). Eyelid closing, opening and compete blink times were longer in newborn infants than in preschool children at all observation times.Conclusions: Newborn infants had a different pattern of eyelid movement compared with preschool children. Specific characteristics that are found in this group of children particularly, such as immaturity of the neural system and more resistant tear film, may explain these findings in part.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)