1,720,957 research outputs found
METODO PER IMPARTIRE COMANDI PER MEZZO DI MOVIMENTI OCULARI
No full textMetodo per impartire comandi per mezzo di movimenti oculari, caratterizzato dal fatto di comprendere le seguenti fasi: rilevazione di un fotogramma della pupilla e rilevamento di una posizione iniziale di fissazione del centro della pupilla (O); posizionamento del centro di un fascio discreto di rette in corrispondenza del centro della pupilla (O) e partizione del piano del fotogramma in regioni discrete; posizionamento in corrispondenza del centro della pupilla (O) del centro di un fascio discreto di semirette orientate; associazione di ciascuna regione discreta ad una specifica semiretta orientata appartenente al fascio discreto di semirette orientate; rilevazione di una posizione finale di fissazione assunta dal centro della pupilla (O) dopo uno spostamento rispetto alla posizione iniziale di fissazione; individuazione di un primo vettore di spostamento del centro della pupilla (O) avente origine nella posizione iniziale del centro della pupilla (O) e vertice nella posizione finale del centro della pupilla (O); associazione ad una delle semirette orientate del fascio discreto alla direzione e al verso di un primo vettore di spostamento assegnabile ad un oggetto da muoversi (P); attribuzione al primo vettore di spostamento dell’oggetto (P) associato alla detta semiretta orientata del fascio discreto, di un modulo uguale al modulo del primo vettore di spostamento del centro della pupilla (O) moltiplicato per un fattore di guadagno predeterminato
Development of a low cost eye gaze tracker
No full textEye gaze tracker is a device for monitoring and recording eye motion and related eye data. It is a hands-off, not intrusive, remote human-computer interface that can be used to track a user's gazepoint. It allows an operator to interact with their environment using only their eyes. During 2 decades of development, hundreds of eyegaze, eye-controlled, computer/communication systems have been sold around the world, primarily as an assistive device for people with disabilities and as a tool for human factors research. Gaze information plays an important role in identifying a person's focus of attention. The information can provide useful communication cues to a multimodal interface. A person's gaze direction is determined by two factors: the orientation of the head, and the orientation of the eyes. While the orientation of the head determines the overall direction of the gaze, the orientation of the eyes determines the exact gaze direction and is limited by the head orientation. To be applied in general computer interfaces, an ideal eye tracker should: be precise to minutes of arc; have repetitive behaviour; work under different conditions such as lighting fluctuations, operator with glasses and contact etc; allow for free head motion; be easy to use on a variety of subjects. This paper regards the development of an economic and ergonomic eye gaze tracker using time compression techniques. A low cost and custom fit approach is used in the development of this Eye gaze tracker: a single low-cost B/W mini-camera (Table 1) is used to acquire video images. A good image contrast is obtained using one IR LED, positioned in proximity of the camera, with orientation suitable to produce the dark-pupil effect: this setup allows an easy pupil image identification. The device shape is designed on a head virtual model obtained from the digitalization of a physical pattern; the point cloud of the head physical model is acquired using a laser scanner. The functional prototypes are produced using the fused deposition modelling (ABS) and selective laser sintering techniques(aluminium/polyammide). Fifty users (students) tested the functional prototypes, complete of all components to evaluate the functional and ergonomic device characteristics. The final cost of the prototype obtained is about 10% of the cost of the product available in the market
Optical and electrical recording of neural activity evoked by graded contrast visual stimulus
Full text linkAbstract Background Brain activity has been investigated by several methods with different principles, notably optical ones. Each method may offer information on distinct physiological or pathological aspects of brain function. The ideal instrument to measure brain activity should include complementary techniques and integrate the resultant information. As a "low cost" approach towards this objective, we combined the well-grounded electroencephalography technique with the newer near infrared spectroscopy methods to investigate human visual function. Methods The article describes an embedded instrumentation combining a continuous-wave near-infrared spectroscopy system and an electroencephalography system to simultaneously monitor functional hemodynamics and electrical activity. Near infrared spectroscopy (NIRS) signal depends on the light absorption spectra of haemoglobin and measures the blood volume and blood oxygenation regulation supporting the neural activity. The NIRS and visual evoked potential (VEP) are concurrently acquired during steady state visual stimulation, at 8 Hz, with a b/w "windmill" pattern, in nine human subjects. The pattern contrast is varied (1%, 10%, 100%) according to a stimulation protocol. Results In this study, we present the measuring system; the results consist in concurrent recordings of hemodynamic changes and evoked potential responses emerging from different contrast levels of a patterned stimulus. The concentration of [HbO2] increases and [HHb] decreases after the onset of the stimulus. Their variation shows a clear relationship with the contrast value: large contrast produce huge difference in concentration, while low contrast provokes small concentration difference. This behaviour is similar to the already known relationship between VEP response amplitude and contrast. Conclusion The simultaneous recording and analysis of NIRS and VEP signals in humans during visual stimulation with a b/w pattern at variable contrast, demonstrates a strong linear correlation between hemodynamic changes and evoked potential amplitude. Furthermore both responses present a logarithmic profile with stimulus contrast.</p
Combining Near-Infrared Spectroscopy and Electroencephalography to Monitor Brain Function
No full textWe propose to embed a continuous-wave near-infrared spectroscopy system within an electroencephalography system to perform functional hemodynamic and neural response simultaneously. In this study, we present the measuring system and the results consisting in changes of oxyhemoglobin and deoxyhemoglobin derived from continuous-wave near-infrared spectroscopy data and the evoked potential responses derived from the electroencephalography recordings. A checkerboard stimulus was adopted to elicit a response signal from the visual cortex. The results collected demonstrate that near infrared spectroscopy can detect task-induced changes in hemodynamics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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