Mostrando recursos 1 - 20 de 39.923

  1. Navigating without vision: Basic and applied research

    Jack M. Loomis; Roberta L. Klatzky; Reginald G. Golledge
    ABSTRACT: We describe some of the results of our program of basic and applied research on navigating without vision. One basic research topic that we have studied extensively is path integration, a form of navigation in which perceived self-motion is integrated over time to obtain an estimate of current posilion and orientation. In experiments on pathway completion, one test of path integration ability, we have found that subjects who are passively guided over the outbound path without vision exhibit significant errors when attempting to return to the origin but are nevertheless sensitive to turns and segment lengths in the stimulus...

  2. A wearable attitude measurement system using a fiber optic gyroscope

    Masayuki Okihara; Tokimec Inc
    An attitude-measurement system (TISS-5-40) has been developed to achieve a wearable sensor for individuals. This equipment is one of the inertial sensor systems having three �beroptic gyroscopes and three accelerometers. Heading stability of 1 deg./hr. (1s) and attitude accuracy of 60.5 deg. have been demonstrated. At present, some of the attitude-measurement Systems have been applied in the �eld of mixed-reality technology, and the users con�rm and report its effectiveness

  3. Estimating Coloured 3D Face Models from Single Images: An Example Based Approach

    Thomas Vetter; Volker Blanz
    Abstract. In this paper we present a method to derive 3D shape and surface texture of a human face from a single image. The method draws on a general flexible 3D face model which is “learned ” from examples of individual 3D-face data (Cyberware-scans). In an analysis-by-synthesis loop, the flexible model is matched to the novel face image. From the coloured 3D model obtained by this procedure, we can generate new images of the face across changes in viewpoint and illumination. Moreover, nonrigid transformations which are represented within the flexible model can be applied, for example changes in facial expression....

  4. Compact and Temperature Independent Electro-optic Switch Based on Slotted Silicon Photonic Crystal Directional Coupler

    Hassan Aghababaeian; Mohammad-hashem Vadjed-samiei
    In this paper, we have proposed a principle to design a compact and temperature independent electro-optic switch based on a slotted photonic crystal directional coupler (SPCDC). Infiltration of the slotted silicon photonic crystal with polymer enhances the slow light and decreases the switching length, whereas the different signs of thermo-optic coefficients of the polymer and silicon make the proposed switch stable within 25 ℃ to 85 ℃ temperature range. The SPCDC structure is modified to increase poling efficiency of the polymer in the slot and to flatten the dispersion diagram of the even mode to minimize the switching length.

  5. $rec.titulo


    examination revealed ptosis and medial rectus palsy in both eyes. The pupils were bilaterally symmetrical with normal reaction to light and accommodation. The examina-tion of the optic fundi revealed papilledema stage 2 (early papilledema per Frisen scale). However, no abnormalities were noted during the examination of the motor and sen-sory systems. She had no signs of meningeal involvement. The examination of the other systems was within normal limits. The relevant hematological investigations, including erythrocyte sedimentation rate, were normal. Her lumbar puncture showed an increased opening pressure (280 mm of water). The cerebrospinal fluid was clear with normal cell count and...

  6. Correspondence to

    Dean M. Wingerchuk; Brenda Banwell Md; Jeffrey L. Bennett; William Carroll Md; Tanuja Chitnis Md; Benjamin Greenberg; Michael Levy; Jack H. Simon; Silvia Tenembaum Md; Anthony L. Traboulsee; Patrick Waters Phd; Kay E. Wellik; Brian G. Weinshenker
    Editorial, page 118 Supplemental data at Neurology.org International consensus diagnostic criteria for neuromyelitis optica spectrum disorders Neuromyelitis optica (NMO) is an inflammatory CNS syndrome distinct from multiple sclerosis (MS) that is associated with serum aquaporin-4 immunoglobulin G antibodies (AQP4-IgG). Prior NMO diagnostic criteria required optic nerve and spinal cord involvement but more restricted or more extensive CNS involvement may occur. The International Panel for NMO Diagnosis (IPND) was convened to develop revised diagnostic criteria using systematic literature reviews and elec-tronic surveys to facilitate consensus. The new nomenclature defines the unifying term NMO spectrum disorders (NMOSD), which is stratified further by...

  7. Predicting multiple sclerosis at optic neuritis onset

    Yp Jin; J De Pedro-cuesta; Yh Huang
    Using multivar iate analyses, individual risk of clinically definite multiple sclero sis (CDMS) after monosymptomatic optic neur itis (MON) was quantified in a pro spective study with clinical MON onset dur ing 1990 /95 in Stockho lm, Sweden. During amean follow-up time of 3.8 years, the presence of MS-like brain magnetic resonance imaging (MRI) lesions and o ligoclonal immunoglobulin (Ig) G bands in cerebro spinal fluid (CSF) were strong prognostic markers o f CDMS, with relative hazard ratio s of 4.68 {95 % confidence interval (C I) 2.21 /9.91} and 5.39 (95 % C I 1.56 /18.61), respectively. Age and...

  8. $rec.titulo

    A. Charles
    Included in the proceedings of a 1973 workshop on the education of deaf blind children are four papers on aspects of diagnosis and remediation. Roger Seelye discusses vision, visual anomalies, and the implications of low vision conditions such as cataracts, glaucoma, retrolental fibroplasia, and optic atrophy. The low vision aids workshop is summarized by George Gore who reported the demonstration of assessment and simulation role playing techniques. Mary Clare Boroughs considers issues of testing and provides a list of tests appropriate for multiply-handicapped children. Mary Gray reviews growth and development in terms of biogenetic, psychodynamic, behaviorist, sociological, ecological, and developmental...

  9. Journal ofNeurology, Neurosurgery, and Psychiatry 1989;52:115-117 Short report Multiple sclerosis following optic neuritis in Chile

    Gonzalo Alvarez; Manuel Cardenas
    SUMMARY Twenty three unselected cases of optic neuritis were re-examined between 2 and 18 years after the onset of the disease, with a mean of 9 7 years. Only 8/23 (35%) had unilateral non-recurrent disease. One patient only (4-3%) went on to develop multiple sclerosis. These findings support the impression that demyelinating disease varies considerably in Latin America compared with northem industrialised countries. The prevalence of multiple sclerosis in South America is unknown. Its geoclimatic and ethnic heterogeneity makes generalisations hazardous but in the northern hemisphere Mexico, whose cultural similarities to South American societies are obvious, has been repor-ted to...

  10. $rec.titulo


    in children can also be developed from- growing cataract, juvenile glaucoma, optic atrophy, hereditary macular degeneration etc.1-3 Transmission of reduced vision is generally

  11. 418 PUBLICATIONS 4,227 CITATIONS SEE PROFILE

    Luis Ferreira; José Luis Santos; Faramarz Farahi
    Polarization-induced noise in a fiber-optic

  12. DOI: 10.13189/ujpa.2014.020206 Two-Element Phased-Array Acousto-Optic Deflector at High Diffraction Efficiency: Scanning Range Broadening

    Sergey Antonov; Valery Proklov; Yuri Rezvov; Er Vainer
    Abstract An acousto-optic deflector with a two-element phased-array piezoelectric transducer is investigated at high diffraction efficiency (close to 100%). Significant broadening of the frequency band (and, thus, the angular scanning range) relative to the well-known low efficiency regime is theoretically predicted and experimentally demonstrated. Experiments with an off-axis deflector based on paratellurite (TeO2), a 1.06 µm light radiation and 6 mm interaction length gave frequency band from 17 to 48 MHz at an efficiency of no less than 94 % of the maximum value.

  13. Micro Grinding Technique of Mutilcore Fiber Endface Using 3D Flock-structured Film

    L. B. Zheng; J. Xie; Tee Koon Na; H. F. Xie
    Abstract. In order to control the 1~2-um protrusion height of mutilcore (MT) fiber endface in optic connectors, a micro grinding approach was developed using a 3D flock-structured film. The objective is to replace traditional lapping with loose-abrasive slurry. Experimental result shows that to achieve its height requirement and good quality, this approach requires 5-steps grinding processes with normal coated lapping film and three-dimensional coated flock lapping film. It is found that using 3-um-size silicon carbide flock lapping film, the grinding time and the pressure are the key factors to control he 1~2-um protrusion height of fiber endface. Moreover, the endface...

  14. $rec.titulo

    Pesqui Odontol Bras; Luiz Felipe; Rodrigues Graziottin; Nilza Pereira Da Costa; Ivori Dutra Da Silveira; Elaine Bauer Veeck
    Measurement of the optical density of packable composites – comparison between direct and indirect digital systems Mensuração da densidade óptica de compósitos compactáveis – comparação entre sistemas digitais direto e indireto

  15. Volumetric Assessment of Optic Nerve Sheath and Hypophysis

    In Idiopathic Intracranial Hypertension; J. Hoffmann; C. Schmidt; H. Kunte; R. Klingebiel; L. Harms; E. Wiener
    BACKGROUND AND PURPOSE: Idiopathic intracranial hypertension is a headache syndrome characterized by increased CSF pressure. Compression of the hypophysis and distension of the optic nerve sheath are reliable imaging signs. The purpose of the study was to validate, in patients with idiopathic intracranial hypertension, MR imaging–based volumetric measurements of the optic nerve sheath and hypophysis as an objective observation method for more accurate diagnosis and posttreatment follow-up. MATERIALS AND METHODS: Twenty-three patients with idiopathic intracranial hypertension as well as age-, sex-, and body mass index–matched controls underwent volumetric measurements of the optic nerve, optic nerve sheath, and hypophysis on high-resolution...

  16. Distinct mechanisms of impairment in cognitive ageing and Alzheimer's disease

    Mark Mapstone; Kathryn Dickerson; Charles J. Duffy
    Similar manifestations of functional decline in ageing and Alzheimer’s disease obscure differences in the under-lying cognitive mechanisms of impairment.We sought to examine the contributions of top-down attentional and bottom-up perceptual factors to visual self-movement processing in ageing and Alzheimer’s disease. We administered a novel heading discrimination task requiring subjects to determine direction of simulated self-movement from left or right offset optic flow fields of several sizes (25u, 40u or 60u in diameter) to 18 Alzheimer’s disease subjects (mean age = 75.3, 55 % female), 21 older adult control subjects (mean age=72.4, 67 % female), and 26 younger control subjects (mean...

  17. JUVENILE SYSTEMIC LUPUS ERYTHEMATOSUS NEUROLOGICAL INVOLVEMENT

    Maria Odetehilário; Charlesk Naspitz
    ABSTRACT- With the purpose of analyzing the neurological involvement due to systemic lupus erythematosus (SLE), we evaluated 17 female patients who were seen regularly at the hospital and had been diagnosed as having SLE according to classification criteria proposed by the American College of Rheumatology revised in 1982, before the age of 16. Neurological involvement was detected in 12 patients(71%): headache (35%), extrapyramidal syndrome (35%), epileptic syndrome (24%) pyramidal syndrome (24%), peripheral neuropathy (12%) and optic neuritis (6%). The findings of CT scan (58%) and cerebrospinal fluid (50%) were most closely correlated to clinical neurological involvement. KEY WORDS: juvenile systemic...

  18. Histopathologic Validation of Angioscopy and

    Intravascular Ultrasound; Jang-seong Chae
    Background. To establish a histopathologic basis for angioscopic and ultrasound image interpretation we studied 70 postmortem human arterial segments in vitro. Methods and Results. We used 7- to 9-French fiber-optic angioscopes and 20- to 30-MHz intravascular ultrasound imaging catheters. Three observers assigned an angioscopic and ultrasound image classification to each vessel segment. The image and histological classifica-tion categories were then compared. The sensitivity, specificity, and accuracy of both methods separately or in combination for normal vessels were each greater than or equal to 95%. The predictive value was better for angioscopy than for ultrasound due to incorrect ultrasound interpretations of...

  19. Effect of Ischemia on Calcium-Dependent Fluorescence Transients in Rabbit Hearts Containing Indo 1 Correlation with Monophasic Action Potentials and Contraction

    Michael R. Franz; William T. Clusin
    The effects of acute global ischemia on cytosolic calcium transients were studied in perfused rabbit hearts loaded with the fluorescent calcium indicator indo 1. Indo 1-loaded hearts were illuminated at 360 nm, and fluorescence was recorded simultaneously at 400 and 550 nm from the epicardial surface of the left ventricle. The F4m/F550 ratio was calculated by an analog circuit, which allowed cancellation of optical motion artifact. Resulting calcium transients demon-strated a rapid upstroke and slow decay similar to those recorded in isolated ventricular myocytes. Global ischemia rapidly suppressed contraction, but it produced a concurrent increase in the systolic and diastolic...

  20. Performance of Embedded Fiber Optic Sensors in Composite Structures

    Falah M. Wegian; Falah A. Almottiri
    The technology of fiber optic sensors, initially developed for use in aerospace industry, is currently investigated for its applicability in civil engineering. Advances in the structural application of this technology will facilitate the use of built-in monitoring capability in reinforced concrete members, and consequently enable the production of smart structures. This paper investigates the development of a Fiber Optic Bragg Grating Sensor (FOBGS) for embedding in concrete members to measure strain and monitor cracks. Tests were carried out on a steel plate subjected to flexural stress and reinforced concrete beams subjected to axial tensile stress and temperature change. The FOBGS...

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.