Entropia conjunta de espaço e reqüência espacial estimada através da discriminação de estímulos espaciais com luminância e cromaticidade moduladas por funções de Gábor: implicações para o processamento paralelo de informação no sistema visual humano

O objetivo deste estudo foi estimar a entropia conjunta do sistema visual humano no domínio do espaço e no domínio das freqüências espaciais através de funções psicométricas. Estas foram obtidas com testes de discriminação de estímulos com luminância ou cromaticidade moduladas por funções de Gábor. A essência do método consistiu em avaliar a entropia no domínio do espaço, testando-se a capacidade do sujeito em discriminar estímulos que diferiam apenas em extensão espacial, e avaliar a entropia no domínio das freqüências espaciais, testando-se a capacidade do sujeito em discriminar estímulos que diferiam apenas em freqüência espacial. A entropia conjunta foi calculada, então, a partir desses dois valores individuais de entropia. Três condições visuais foram estudadas: acromática, cromática sem correção fina para eqüiluminância e cromática com correção para eqüiluminância através de fotometria com flicker heterocromático. Quatro sujeitos foram testados nas três condições, dois sujeitos adicionais foram testados na condição cromática sem eqüiluminância fina e um sétimo sujeito também fez o teste acromático. Todos os sujeitos foram examinados por oftalmologista e considerados normais do ponto de vista oftálmico, não apresentando relato, sintomas ou sinais de disfunções visuais ou de moléstias potencialmente capazes de afetar o sistema visual. Eles tinham acuidade visual normal ou corrigida de no mínimo 20/30. O trabalho foi aprovado pela Comissão de Ética em Pesquisa do Núcleo de Medicina Tropical da UFPA e obedeceu às recomendações da Declaração de Helsinki. As funções de Gábor usadas para modulação de luminância ou cromaticidade compreenderam redes senoidais unidimensionais horizontais, moduladas na direção vertical, dentro de envelopes gaussianos bidimensionais cuja extensão espacial era medida pelo desvio padrão da gaussiana. Os estímulos foram gerados usando-se uma rotina escrita em Pascal num ambiente Delphi 7 Enterprise. Foi utilizado um microcomputador Dell Precision 390 Workstation e um gerador de estímulos CRS VSG ViSaGe para exibir os estímulos num CRT de 20”, 800 x 600 pixels, 120 Hz, padrão RGB, Mitsubishi Diamond Pro 2070SB. Nos experimentos acromáticos, os estímulos foram gerados pela modulação de luminância de uma cor branca correspondente à cromaticidade CIE1931 (x = 0,270; y = 0,280) ou CIE1976 (u’ = 0,186; v’= 0,433) e tinha luminância média de 44,5 cd/m2. Nos experimentos cromáticos, a luminância média foi mantida em 15 cd/m2 e foram usadas duas series de estímulos verde-vermelhos. Os estímulos de uma série foram formados por duas cromaticidades definidas no eixo M-L do Espaço de Cores DKL (CIE1976: verde, u’=0,131, v’=0,380; vermelho, u’=0,216, v’=0,371). Os estímulos da outra série foram formados por duas cromaticidades definidas ao longo de um eixo horizontal verde-vermelho definido no Espaço de Cores CIE1976 (verde, u’=0,150, v’=0,480; vermelho, u’=0,255, v’=0,480). Os estímulos de referência eram compostos por redes de três freqüências espaciais diferentes (0,4, 2 e 10 ciclos por grau) e envelope gaussiano com desvio padrão de 1 grau. Os estímulos de testes eram compostos por uma entre 19 freqüências espaciais diferentes em torno da freqüência espacial de referência e um entre 21 envelopes gaussianos diferentes com desvio padrão em torno de 1 grau. Na condição acromática, foram estudados quatro níveis de contraste de Michelson: 2%, 5%, 10% e 100%. Nas duas condições cromáticas foi usado o nível mais alto de contraste agregado de cones permitidos pelo gamut do monitor, 17%. O experimento consistiu numa escolha forçada de dois intervalos, cujo procedimento de testagem compreendeu a seguinte seqüência: i) apresentação de um estímulo de referência por 1 s; ii) substituição do estímulo de referência por um fundo eqüiluminante de mesma cromaticidade por 1 s; iii) apresentação do estímulo de teste também por 1 s, diferindo em relação ao estímulo de referência seja em freqüência espacial, seja em extensão espacial, com um estímulo sonoro sinalizando ao sujeito que era necessário responder se o estímulo de teste era igual ou diferente do estímulo de referência; iv) substituição do estímulo de teste pelo fundo. A extensão espacial ou a freqüência espacial do estímulo de teste foi mudada aleatoriamente de tentativa para tentativa usando o método dos estímulos constantes. Numa série de 300 tentativas, a freqüencia espacial foi variada, noutra série também de 300 tentativas, a extensão espacial foi variada, sendo que cada estímulo de teste em cada série foi apresentado pelo menos 10 vezes. A resposta do indivíduo em cada tentativa era guardada como correta ou errada para posterior construção das curvas psicométricas. Os pontos experimentais das funções psicométricas para espaço e freqüência espacial em cada nível de contraste, correspondentes aos percentuais de acertos, foram ajustados com funções gaussianas usando-se o método dos mínimos quadrados. Para cada nível de contraste, as entropias para espaço e freqüência espacial foram estimadas pelos desvios padrões dessas funções gaussianas e a entropia conjunta foi obtida multiplicando-se a raiz quadrada da entropia para espaço pela entropia para freqüência espacial. Os valores de entropia conjunta foram comparados com o mínimo teórico para sistemas lineares, 1/4π ou 0,0796. Para freqüências espaciais baixas e intermediárias, a entropia conjunta atingiu níveis abaixo do mínimo teórico em contrastes altos, sugerindo interações não lineares entre dois ou mais mecanismos visuais. Este fenômeno occorreu em todas as condições (acromática, cromática e cromática eqüiluminante) e foi mais acentuado para a frequência espacial de 0,4 ciclos / grau. Uma possível explicação para este fenômeno é a interação não linear entre as vias visuais retino-genículo-estriadas, tais como as vias K, M e P, na área visual primária ou em níveis mais altos de processamento neural.

Division of labor between M and P visual pathways: different visual pathways minimize joint entropy differently

Visual perception and action are strongly linked with parallel processing channels connecting the retina, the lateral geniculate nucleus, and the input layers of the primary visual cortex. Achromatic vision is provided by at least two of such channels formed by the M and P neurons. These cell pathways are similarly organized in primates having different lifestyles, including species that are diurnal, nocturnal, and which exhibit a variety of color vision phenotypes. We describe the M and P cell properties by 3D Gábor functions and their 3D Fourier transform. The M and P cells occupy different loci in the Gábor information diagram or Fourier Space. This separation allows the M and P pathways to transmit visual signals with distinct 6D joint entropy for space, spatial frequency, time, and temporal frequency. By combining the M and P impacts on the cortical neurons beyond V1 input layers, the cortical pathways are able to process aspects of visual stimuli with a better precision than it would be possible using the M or P pathway alone. This performance fulfils the requirements of different behavioral tasks.

Percepção visual da cidade: iconografias da natureza urbana de Belém (1808 – 1908)

Este estudo propõe uma análise das iconografias urbanas de Belém, produzidas no decorrer do século XIX e início do XX. A tese tem por objetivo, então, analisar a representação da natureza em Belém, especificamente nos anos de 1808 a 1908. O compromisso inicial desse estudo se concentrou em pesquisar os diversos tipos de iconografias sobre Belém no decorrer dos Oitocentos. As questões que se procurou evidenciar tratam sobre a forma como os viajantes apreenderam a cidade, em sua passagem por Belém, tanto sob o ponto de vista narrativo quanto o visual, até os anos de 1890. A partir de então, também identificar como os governantes promoveram a cidade para além da região Amazônica. Observa-se que a natureza brasileira passou a ser representada, a partir do século XIX, por meio de linguagem escrita e iconográfica, isto graças à influência do cientificismo e da sensibilidade artística romântica, que perpassaram pelo conhecimento do país. A sensibilidade romântica realizou a aproximação entre ciência e estética ao apreender e representar a natureza, numa visão totalizante, inaugurando uma nova concepção de paisagem e a tentativa de “inventar” e visualizar uma natureza urbana, a qual é tema principal desse estudo; representa o fenômeno da urbanização que foi registrado, especialmente, por meio da fotografia. Nesse tipo de fotografias, a natureza aparece domesticada, adaptada ao desenho urbano, sua forma artificiosa e geométrica é valorizada. A fotografia urbana do final do século XIX reintroduz o “belo ideal” nas imagens da natureza ordenada segundo o modelo dos jardins franceses, ingleses e italianos. Parto do pressuposto de que a contemplação da natureza é adaptada para a realidade da região Amazônica, embora estivessem presentes modelos provenientes da Europa, mas encontram as suas especificidades a partir de uma natureza exuberante da Amazônia A percepção de natureza na Amazônia da segunda metade do século XIX e a influência de novas formas de conceber a natureza foram projetadas para as cidades na reformulação dos espaços para constituir a área verde, especialmente de Belém. Pensar historicamente a representação da natureza é refletir sobre a sua apropriação pela ação humana ao mesmo tempo em que diferentes indivíduos e grupos sociais circularam e deixaram suas marcas específicas nos lugares construídos a partir de uma natureza domesticada na paisagem urbana.

Limits of Visual Detection for Finasteride Polymorphs in Prepared Binary Mixtures: Analysis by X-ray Powder Diffraction

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

Automatic visual dictionary generation through optimum-path forest clusteringautomatic visual dictionary generation through optimum-path forest clustering

Image categorization by means of bag of visual words has received increasing attention by the image processing and vision communities in the last years. In these approaches, each image is represented by invariant points of interest which are mapped to a Hilbert Space representing a visual dictionary which aims at comprising the most discriminative features in a set of images. Notwithstanding, the main problem of such approaches is to find a compact and representative dictionary. Finding such representative dictionary automatically with no user intervention is an even more difficult task. In this paper, we propose a method to automatically find such dictionary by employing a recent developed graph-based clustering algorithm called Optimum-Path Forest, which does not make any assumption about the visual dictionary's size and is more efficient and effective than the state-of-the-art techniques used for dictionary generation.

Programa para gerenciamento de rebanho leiteiro

With the advent of technology, many repetitive processes before now was be simplified with the support of a simple computer. Therefore programming has been developed and new softwares appear every day. For the development of this project was used the Microsoft Visual Studio 2010, and with it the program was made in C # Windows Form mode. This work aims to develop a program that can read, send and receive data via the Universal Serial Bus (USB) to the computer, and thereby perform the processing. Thus the milk producer will possess the knowledge of the amount of milk produced by the animal. With the processing of data it is possible to generate graphs of herd production or a specific animal and you can also generate the required report date

Programa de equoterapia: intervenção com um praticante com deficiência visual

The hippotherapy is a therapeutic and educational method that uses the horse within an interdisciplinary approach in the areas of health, education and riding, seeking the biopsychosocial development of people with disabilities and/or special needs. The method generates the practitioner positive effects, such as physical, social and psychological benefits. The goal of this study was to investigate alterations with a practitioner with visual impairment during their participation in a hippotherapy program. The study is characterized by a qualitative and descriptive research, in the form of case study. Data were collected through interviews with the mother of the practitioner and filming, photographs and systematic observation of the sessions. Improvements were found in the behavior of practicing at home, and there was progress in motor performance, and self-confidence generated by the domain horse. It is concluded that the hippotherapy program generated physical, psychological and social benefits to the practitioner.

Um estudo sobre a intervenção com o professor de educação física para a inclusão educacional do aluno com deficiência visual

It was aimed to identify how the physical education teachers worked to include a student with visual impairment; intervene with the teacher from the identified necessities and assess the intervention. Data were collected in three stages: 1) Weekly monitoring and filming the classes, 2) intervention by the reflection of videos coming from the previous step and suggesting new actions, 3) development of filming for evaluating the intervention. Before the intervention, it was identified that the explanation of the activities happened collectively. It was held the physical help as the first form of instruction, the student with visual impairment participation occurred depending on the company of a classmate who held hands and did the activities together. Along the intervention it was reflected about the structure of the classes, the ways of explanation of the activities and the strategies and the resources to assure an enjoyable participation of students with visual impairments. The training of peer tutors was a strategy used. After the intervention it was identified in the classroom the assistance of the trained peer tutors; the maintenance of oral explanation and demonstration, though, the first way to explanation for the student with visual impairment started to be the oral tip.

Diretrizes para análise e desenvolvimento de identidade visual: contribuições para o design ergonômico

Currently, too much visual information present in all media is form vehemently, for example, in print media and interfaces used for publicity in conjunction with informational design. This visual information has great influence in the lives of human beings, since the vision of these individuals is the sense most used. Studies on visual identity have not explored this issue in a satisfactory manner, favoring thus the subject of this little development projects in the area. Note the need for analyzes to enable implementation principles of projective, making them accessible to the understanding of most individuals. This study aimed to propose an evaluation of visual identities, which were analyzed by means of visual concepts of usability, design methodologies and Gestalt. We contacted design firms specializing in visual identity projects, places where interviews were conducted to collect the marks allowed for analysis. The results point to a frequent demand the employment of visual usability principles, design methodologies and design in Gestalt visual identities.

Ensino de Física para alunos com deficiência visual: o processo de ensino-aprendizagem nos ambientes escolares das salas de aula regular e de recursos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A equoterapia como auxiliar no processo de inclusão do aluno com deficiência visual: estudo de caso

This study examines the hippotherapy related to school inclusion. Inclusive education, given the diversity of human kind, seeks to understand and meet the educational needs of all students. Visual impairment is defined as a reduction or complete loss of ability to see with the better eye and after the best possible optical correction, and may be perceived by the focus when the individual educational needs of Braille for their learning. Hippotherapy is a therapeutic and educational method that uses the horse in an interdisciplinary approach in health, education and riding, searching for the biopsychosocial development of people with disabilities and/or special needs. The general objectives were: to follow a Hippotherapy program applied to a student with visual disabilities included in regular education from the practice sessions of hippotherapy and the student's school routine, and specific: to verify changes to a student with visual impairment during their participation in an equine therapy program, to check the commitment, involvement and interest in school activities the student practicing hippotherapy inserted into the regular school system. The methodology was a qualitative research, in the form of case study. The instruments of data collection were interviews, video recordings, photographs, school information and the subject of systematic observations of the sessions of hippotherapy. Interviews were conducted at three different times during the course of the program. First we used a strategy for succeeding in increasing the involvement of practicing with the school. Later, another strategy was established, consisting of the effective presence of the researcher in the school to carry out activities on the hippotherapy within the school environment. The analysis of the first interview showed no changes in school interest, however, occurred in the family environment. In analyzing the results of the second interview was seen as a...

The Perception of Natural, Cell Phone, and Computer-Synthesized Speech During The Performance Of Simultaneous Visual-Motor Tasks

This study investigated the influence of top-down and bottom-up information on speech perception in complex listening environments. Specifically, the effects of listening to different types of processed speech were examined on intelligibility and on simultaneous visual-motor performance. The goal was to extend the generalizability of results in speech perception to environments outside of the laboratory. The effect of bottom-up information was evaluated with natural, cell phone and synthetic speech. The effect of simultaneous tasks was evaluated with concurrent visual-motor and memory tasks. Earlier works on the perception of speech during simultaneous visual-motor tasks have shown inconsistent results (Choi, 2004; Strayer & Johnston, 2001). In the present experiments, two dual-task paradigms were constructed in order to mimic non-laboratory listening environments. In the first two experiments, an auditory word repetition task was the primary task and a visual-motor task was the secondary task. Participants were presented with different kinds of speech in a background of multi-speaker babble and were asked to repeat the last word of every sentence while doing the simultaneous tracking task. Word accuracy and visual-motor task performance were measured. Taken together, the results of Experiments 1 and 2 showed that the intelligibility of natural speech was better than synthetic speech and that synthetic speech was better perceived than cell phone speech. The visual-motor methodology was found to demonstrate independent and supplemental information and provided a better understanding of the entire speech perception process. Experiment 3 was conducted to determine whether the automaticity of the tasks (Schneider & Shiffrin, 1977) helped to explain the results of the first two experiments. It was found that cell phone speech allowed better simultaneous pursuit rotor performance only at low intelligibility levels when participants ignored the listening task. Also, simultaneous task performance improved dramatically for natural speech when intelligibility was good. Overall, it could be concluded that knowledge of intelligibility alone is insufficient to characterize processing of different speech sources. Additional measures such as attentional demands and performance of simultaneous tasks were also important in characterizing the perception of different kinds of speech in complex listening environments.

A equoterapia como auxiliar no processo de inclusão do aluno com deficiência visual: estudo de caso

This study examines the hippotherapy related to school inclusion. Inclusive education, given the diversity of human kind, seeks to understand and meet the educational needs of all students. Visual impairment is defined as a reduction or complete loss of ability to see with the better eye and after the best possible optical correction, and may be perceived by the focus when the individual educational needs of Braille for their learning. Hippotherapy is a therapeutic and educational method that uses the horse in an interdisciplinary approach in health, education and riding, searching for the biopsychosocial development of people with disabilities and/or special needs. The general objectives were: to follow a Hippotherapy program applied to a student with visual disabilities included in regular education from the practice sessions of hippotherapy and the student's school routine, and specific: to verify changes to a student with visual impairment during their participation in an equine therapy program, to check the commitment, involvement and interest in school activities the student practicing hippotherapy inserted into the regular school system. The methodology was a qualitative research, in the form of case study. The instruments of data collection were interviews, video recordings, photographs, school information and the subject of systematic observations of the sessions of hippotherapy. Interviews were conducted at three different times during the course of the program. First we used a strategy for succeeding in increasing the involvement of practicing with the school. Later, another strategy was established, consisting of the effective presence of the researcher in the school to carry out activities on the hippotherapy within the school environment. The analysis of the first interview showed no changes in school interest, however, occurred in the family environment. In analyzing the results of the second interview was seen as a...

Psychophysical analysis of contrast processing segregated into magnocellular and parvocellular systems in asymptomatic carriers of 11778 Leber`s hereditary optic neuropathy

We examined achromatic contrast discrimination in asymptomatic carriers of 11778 Leber`s hereditary optic neuropathy (LHON 18 controls) and 18 age-match were also tested. To evaluate magnocellular (MC) and Parvocellular (PC) contrast discrimination, we used a version of Pokorny and Smith`s (1997) Pulsed/steady-pedestal paradigms (PPP/SPP) thought to be detected via PC and MC pathways, respectively. A luminance pedestal (four 1 degrees x 1 degrees squares) was presented on a 12 cd/m(2) surround. The luminance of one of the squares (trial square, TS) was randomly incremented for either 17 or 133 ms. Observers had to detect the TS, in a forced-choice task, at each duration, for three pedestal levels: 7, 12, 19 cd/m(2). In the SPP, the pedestal was fixed, and the TS was modulated. For the PPP, all four pedestal squares pulsed for 17 or 133 ms, and the TS was simultaneously incremented or decremented. We found that contrast discrimination thresholds of LHON carriers were significantly higher than controls` in the condition with the highest luminance of both paradigms, implying impaired contrast processing with no evidence of differential sensitivity losses between the two systems. Carriers` thresholds manifested significantly longer temporal integration than controls in the SPP, consistent with slowed MC responses. The SPP and PPP paradigms can identify contrast and temporal processing deficits in asymptomatic LHON carriers, and thus provide an additional tool for early detection and characterization of the disease.

Construção e Evidências Psicométricas de uma Escala de Avaliação da Percepção Visual

Este estudo teve como objetivo construir e conhecer os parâmetros psicométricos de um instrumento para análise da percepção visual de adultos. Para a construção da escala participaram 295 adultos saudáveis, sem déficits cognitivos ou perceptivo-visuais. Nesta etapa foi formulada uma escala tetrafatorial constituída por 20 itens que avaliam quatro dimensões referentes à percepção visual: constância da forma, figurafundo, posição e relação espacial. Para obter evidências de validade foi utilizada uma amostra de 183 voluntários com boa saúde física e mental e acuidade visual normal ou corrigida. Os dados obtidos relatam a existência de concordância interjuízes, adequação semântica e significância no teste-reteste do instrumento. Os coeficientes de fidedignidade variaram de 0,84 a 0,93. Os quatro fatores esperados foram encontrados, cada um contendo 5 itens, e juntos explicaram 57,52% da variância do constructo. O instrumento apresentou parâmetros psicométricos adequados, o que pode justificar sua utilidade em pesquisas básicas e na prática clínica.