Search results for "eye"

Sensorimotor aspects of high-speed artificial gravity: I. Sensory conflict in vestibular adaptation

2003

Short-radius centrifugation offers a promising and affordable countermeasure to the adverse effects of prolonged weightlessness. However, head movements made in a fast rotating environment elicit Coriolis effects, which seriously compromise sensory and motor processes. We found that participants can adapt to these Coriolis effects when exposed intermittently to high rotation rates and, at the same time, can maintain their perceptual-motor coordination in stationary environments. In this paper, we explore the role of inter-sensory conflict in this adaptation process. Different measures (vertical nystagmus, illusory body tilt, motion sickness) react differently to visual-vestibular conflict a…

Treatment of Specific Types of Nystagmus

2007

■ The function of the ocular motor system is to hold images stable on the fovea. The vestibular system and the vestibulo-ocular reflex (VOR) also play an important role in this function. The VOR connects the peripheral vestibular endorgans – the semicircular canals and otoliths – with their appropriate pair of eye muscles via a three-neuronal arc.

General remarks on the role of the vestibular system in weightlessness

1987

Different methods are described to experimentally achieve weightlessness. Since the function of the otolith system depends on the presence of contact forces opposing gravity, it is disabled in weightlessness and may send misleading positional information to the brain. Without the contributions of the otolith system it is difficult in space to distinguish self-motion from object motion. Furthermore, the disintegration of information from the neck position receptors from those of the otolith system can lead to additional illusory positional sensations. Since the function of the semicircular canal system in previous space flights was found to be essentially undisturbed, the vestibular experime…

Threshold-based vestibular adaptation to cross-coupled canal stimulation

2008

Prior experiments have demonstrated that people are able to adapt to cross-coupled accelerations associated with head movements while spinning at high rotation rates (e.g., 23 rpm or 138°/s). However, while adapting, subjects commonly experience serious side effects, such as motion sickness, non-compensatory eye movements, and strong and potentially disorienting illusory body tilt or tumbling sensations. In the present study, we investigated the feasibility of adaptation using a threshold-based method, which ensured that the illusory tilt sensations remained imperceptible or just barely noticeable. This was achieved by incrementally increasing the angular velocity of the horizontal centrifu…

Evidence of enhanced bacterial invasion during Diplostomum spathaceum infection in European grayling, Thymallus thymallus (L.)

2006

Farmed grayling, Thymallus thymallus (L.), are susceptible to atypical Aeromonas salmonicida (aAS) infections. Interactions between bacteria and parasites were studied using grayling subjected to concomitant exposure to aAS bacteria and the digenean parasite Diplostomum spathaceum. Atypical AS was detected from fish by a combination of bacterial cultivation and polymerase chain reaction techniques. A detection level of 17 aAS cells per 100 mg intestine tissue sample was obtained. Concomitant bacterial exposure did not enhance the severity of grayling eye rupture and nuclear extrusion induced by D. spathaceum, but D. spathaceum invasion into grayling increased the proportion of fish carrying…

Serological Evidence for Multiple Strains of Canine Norovirus in the UK Dog Population

2013

International audience; Noroviruses are associated with intestinal disease in humans, cows, pigs, mice, and, more recently, dogs. In 2007, the first canine norovirus (CNV) was identified and characterized in Italy. Subsequent studies have identified CNV in stools of dogs from Portugal, Greece, and the United States. To investigate the prevalence of CNV in the UK dog population, 228 canine stool samples were screened for CNV by qPCR, and 396 serum samples were screened for anti-CNV antibodies. qPCR of RNA extracted from canine stool samples did not reveal any CNV-positive samples, based on samples collected from diarrhoeic and control dogs in 2012-2013. CNV virus-like particles to three diff…

Transmission, infectivity and survival of Diplostomum spathaceum cercariae

2003

The transmission dynamics of the cercariae of Diplostomum spathaceum were investigated under laboratory conditions using cercariae collected from naturally infected Lymnaea stagnalis. Cercariae were kept in a constant temperature of 20 °C and the survival and infectivity to naïve young rainbow trout recorded at 3-h intervals until few cercariae were alive. Mortality initially remained constant but increased rapidly after 20 h. While a model of constant mortality fitted the survival data, an age-dependent model provided a better fit and implied that cercariae tended to carry similar quantities of resources and once these were exhausted the cercariae died. Cercarial infectivity also showed an…

La representación de las victorias y conquistas en la medallística de Luis XIV

2005

El arte medallístico tuvo uno de sus más importantes mecenas en la figura de Luis XIV de Francia. En el presente artículo se estudia parte del corpus metálico del monarca galo, en concreto, parte de las medallas que conmemoraron las victorias y conquistas del Rey Sol, aquellas piezas que, por su iconografía, significado e ideología, se destacaron como las predilectas de la corte absoluta más importante de la Europa seiscientista. (A)

2018

Recently, two forms of virtue-related humor, benevolent and corrective, have been introduced. Benevolent humor treats human weaknesses and wrongdoings benevolently, while corrective humor aims at correcting and bettering them. Twelve marker items for benevolent and corrective humor (the BenCor) were developed, and it was demonstrated that they fill the gap between humor as temperament and virtue. The present study investigates responses to the BenCor from 25 samples in 22 countries (overall N = 7,226). The psychometric properties of the BenCor were found to be sufficient in most of the samples, including internal consistency, unidimensionality, and factorial validity. Importantly, benevolen…

Hybrid foveated vision system for video surveillance and robotic navigation

2014

The primary goal of this thesis is to elaborate a binocular vision system using two different types of camera. The system studied here is composed of one omnidirectional camera coupled with a PTZ camera. This heterogeneous association of cameras having different characteristics is called a hybrid stereo-vision system. The couple composed of these two cameras combines the advantages given by both of them, that is to say a large field of view and an accurate vision of a particular Region of interest with an adjustable level of details using the zoom. In this thesis, we are presenting multiple contributions in visual tracking using omnidirectional sensors, PTZ camera self calibration, hybrid v…