Infrared Video System Research Articles

Impacts of dual active-ingredient bed nets on the behavioural responses of pyrethroid resistant Anopheles gambiae determined by room-scale infrared video tracking

BackgroundThe success of insecticide treated bed nets (ITNs) for malaria vector control in Africa relies on the behaviour of various species of Anopheles. Previous research has described mosquito behavioural alterations resulting from widespread ITN coverage, which could result in a decrease in net efficacy. Here, behaviours were compared including timings of net contact, willingness to refeed and longevity post-exposure to two next-generation nets, PermaNet® 3.0 (P3 net) and Interceptor® G2 (IG2 net) in comparison with a standard pyrethroid-only net (Olyset Net™ (OL net)) and an untreated net.MethodsSusceptible and resistant Anopheles gambiae mosquitoes were exposed to the nets with a human volunteer host in a room-scale assay. Mosquito movements were tracked for 2 h using an infrared video system, collecting flight trajectory, spatial position and net contact data. Post-assay, mosquitoes were monitored for a range of sublethal insecticide effects.ResultsMosquito net contact was focused predominantly on the roof for all four bed nets. A steep decay in activity was observed for both susceptible strains when P3 net and OL net were present and with IG2 net for one of the two susceptible strains. Total mosquito activity was higher around untreated nets than ITNs. There was no difference in total activity, the number, or duration, of net contact, between any mosquito strain, with similar behaviours recorded in susceptible and resistant strains at all ITNs. OL net, P3 net and IG2 net all killed over 90% of susceptible mosquitoes 24 h after exposure, but this effect was not seen with resistant mosquitoes where mortality ranged from 16 to 72%. All treated nets reduced the willingness of resistant strains to re-feed when offered blood 1-h post-exposure, with a more pronounced effect seen with P3 net and OL net than IG2 net.ConclusionThese are the first results to provide an in-depth description of the behaviour of susceptible and resistant Anopheles gambiae strains around next-generation bed nets using a room-scale tracking system to capture multiple behaviours. These results indicate that there is no major difference in behavioural responses between mosquito strains of differing pyrethroid susceptibility when exposed to these new ITNs under the experimental conditions used.

A near infra-red video system as a protective diagnostic for electron cyclotron resonance heating operation in the Wendelstein 7-X stellarator.

The Wendelstein 7-X stellarator is a large nuclear fusion device based at Max-Planck-Institut für Plasmaphysik in Greifswald in Germany. The main plasma heating system for steady state operation in W7-X is electron cyclotron resonance heating (ECRH). During operation, part of plama facing components will be directly heated by the non-absorbed power of 1 MW rf beams of ECRH. In order to avoid damages of such components made of graphite tiles during the first operational phase, a near infra-red video system has been developed as a protective diagnostic for safe and secure ECRH operation. Both the mechanical design housing the camera and the optical system are very flexible and respect the requirements of steady state operation. The full system including data acquisition and control system has been successfully tested in the vacuum vessel, including on-line visualization and data storage of the four cameras equipping the ECRH equatorial launchers of W7-X.

Species visitation at free‐choice quail feeders in west texas

AbstractProviding supplemental feed is a common practice for the management of northern bobwhite (Colinus virginianus) and scaled quail (Callipepla squamata). The ecological efficacy and economic efficiency of a feeding program for quail can be evaluated using numerous metrics, including visitation rates by target and non‐target species. We quantified species visitation rates seasonally at free‐choice quail feeders with motion‐sensing cameras at 4 sites in West Texas, USA. Feeders were monitored from autumn 2002 to summer 2003 using both an active‐infrared sensing camera system (TrailMaster 1500®; Goodson & Associates, Inc., Lenexa, KS) and a passive infrared video system (TrophyView®; Wildlife Surveillance Systems, Inc., Kerens, TX). Our camera systems recorded 14 mammal and 18 avian species among 6,558 events observed from 490 days of feeder surveillance. Collectively, northern bobwhite and scaled quail accounted for only 7.3% and 11.3% of all recorded species visitations for the TrophyView and TrailMaster camera systems, respectively. Raccoons (Procyon lotor, 43.2%) and nongame birds (32.5%) comprised the majority of all recorded visitations. Although feeder visitation rates do not necessarily equate to feed consumption, we conclude that the vast majority of the feed in this study was consumed by non‐target species and most notably raccoons. High visitation rates by raccoons at feeders suggest supplemental feeding programs for quail could facilitate targeted removal of a common feed competitor (and potential predator of quail nests) and perhaps improve efficacy of feeding efforts. Managers should consider both direct and indirect effects of providing supplemental feeding efforts. © 2012 The Wildlife Society.

Comparison of Three Different Pelvic Circumferential Compression Devices: A Biomechanical Cadaver Study

Pelvic circumferential compression devices are designed to stabilize the pelvic ring and reduce the volume of the pelvis following trauma. It is uncertain whether pelvic circumferential compression devices can be safely applied for all types of pelvic fractures because the effects of the devices on the reduction of fracture fragments are unknown. The aim of this study was to compare the effects of circumferential compression devices on the dynamic realignment and final reduction of the pelvic fractures as a measure of the quality of reduction. Three circumferential compression devices were evaluated: the Pelvic Binder, the SAM Sling, and the T-POD. In sixteen cadavers, four fracture types were generated according to the Tile classification system. Infrared retroreflective markers were fixed in the different fracture fragments of each pelvis. The circumferential compression device was applied sequentially in a randomized order with gradually increasing forces applied. Fracture fragment movement was studied with use of a three-dimensional infrared video system. Dynamic realignment and final reduction of the fracture fragments during closure of the circumferential compression devices were determined. A factorial repeated-measures analysis of variance with pairwise post hoc comparisons was performed to analyze the differences in pulling force between the circumferential compression devices. In the partially stable and unstable (Tile type-B and C) pelvic fractures, all circumferential compression devices accomplished closure of the pelvic ring and consequently reduced the pelvic volume. No adverse fracture displacement (>5 mm) was observed in these fracture types. The required pulling force to attain complete reduction at the symphysis pubis varied substantially among the three different circumferential compression devices, with a mean (and standard error of the mean) of 43 ± 7 N for the T-POD, 60 ± 9 N for the Pelvic Binder, and 112 ± 10 N for the SAM Sling. The Pelvic Binder, SAM Sling, and T-POD provided sufficient reduction in partially stable and unstable (Tile type-B1 and C) pelvic fractures. No undesirable overreduction was noted. The pulling force that was needed to attain complete reduction of the fracture parts varied significantly among the three devices, with the T-POD requiring the lowest pulling force for fracture reduction.

Editor's Comment and Q&A: Distances between facial landmarks can be measured accurately with a new digital 3-dimensional video system

Introduction The aim of this study was to investigate a new digital 3-dimensional infrared video system to determine its accuracy, precision, and validity in measuring facial distances. Methods Bench experiments were performed by measuring the vertical and diagonal distances of chessboard squares of known length to determine the system's accuracy and precision. To test the system's validity, 16 healthy volunteers participated in this study. Vertical and horizontal distances of the face were measured electronically at rest, and on posed and aggressive smiles. All measurements were repeated after 8 weeks. Direct measurements of the intercanthal distance were obtained twice with calipers. Results A minor systematic error was found in the bench experiments, with the highest absolute error of 0.227 ± 0.39 mm. The analysis with this video system showed good reproducibility of all measured distances when the mean of 2 frames was used to compare distances. Digital measurements of the intercanthal distances showed high agreement with the clinically obtained values. Conclusions This digital video system can measure geometric distances in a 3-dimensional environment with high precision. Facial distances can be measured with good accuracy and precision, allowing applications in research and clinical practice.

Distances between facial landmarks can be measured accurately with a new digital 3-dimensional video system

The aim of this study was to investigate a new digital 3-dimensional infrared video system to determine its accuracy, precision, and validity in measuring facial distances. Bench experiments were performed by measuring the vertical and diagonal distances of chessboard squares of known length to determine the system's accuracy and precision. To test the system's validity, 16 healthy volunteers participated in this study. Vertical and horizontal distances of the face were measured electronically at rest, and on posed and aggressive smiles. All measurements were repeated after 8 weeks. Direct measurements of the intercanthal distance were obtained twice with calipers. A minor systematic error was found in the bench experiments, with the highest absolute error of 0.227 +/- 0.39 mm. The analysis with this video system showed good reproducibility of all measured distances when the mean of 2 frames was used to compare distances. Digital measurements of the intercanthal distances showed high agreement with the clinically obtained values. This digital video system can measure geometric distances in a 3-dimensional environment with high precision. Facial distances can be measured with good accuracy and precision, allowing applications in research and clinical practice.

Surviving in anoxic surroundings: how burrowing aquatic insects create an oxic microhabitat

We used an infrared video system and O2 microelectrodes to record the behavior of 2 widespread burrowing insects, the predatory alderfly Sialis velata and the sediment-feeding mayfly Hexagenia limbata, to determine how they survive in anoxic sediment. Analysis of video recordings showed that both taxa have several common behaviors, including crawling, pushing sediment, turning around, and brushing their legs over their bodies for the purpose of cleaning. In contrast, these taxa differ in how they draw overlying oxic water into their burrows, i.e., H. limbata beats its abdominal gills, whereas S. velata undulates its abdomen. Feeding frequency also differs between the 2 taxa, i.e., the mayfly feeds frequently on sediment within its burrows, whereas S. velata feeds infrequently. Hexagenia limbata nymphs were rarely inactive (<1% of the time) and irrigated their burrows by gill-beating ¾ of the time, whereas S. velata nymphs were usually inactive (60% of the time). By vigorous irrigation of its burrow, H. limbata maintained its surroundings well oxygenated, whereas O2 concentrations fluctuated more widely in burrows of the less-active S. velata. This behavioral difference between the species is consistent with their reported sensitivities to the low O2 concentrations associated with eutrophication; in such situations, H. limbata is likely to be eliminated, whereas S. velata can persist. We estimate that O2 lost from water passing through an H. limbata burrow is taken up mainly by the insect rather than diffusing into the surrounding sediment.

Underwater infrared video system for behavioral studies in lakes

We propose the use of infrared (IR) video systems for the underwater behavioral study of animals at night, at depth, and/or in colored aquatic systems. This system is composed of a black‐and‐white video camera coupled with four projectors, each equipped with 50 IR light‐emitting diodes (LEDs). The use of LEDs is energetically far more efficient than the use of halogen lights equipped with IR filters, and therefore allows automatic long‐term video recording at low cost. Laboratory testing of one LED spot at increasing humic acid concentrations indicates that this system can be used for short‐range underwater observation in colored lakes. We applied this system to the study of scavenger/carcass interactions. Under field conditions, the setup is not easily detected by animals and allows direct and continuous observation of animal interactions during a full daily cycle. Note that, to our knowledge, this video system provides the first published night movies of freshwater fish behavior filmed in highly colored lakes, without using visible light. Our results indicate that this nonintrusive system can be successfully used for scientific studies in freshwater ecology, even in the presence of significant concentrations of light‐absorbing humic substances in the water.

Recording Three-Dimensional Eye Movements: Scleral Search Coils versus Video Oculography

This study compared the performance of a video-based infrared three-dimensional eye tracker device (Chronos) with the scleral search coil method. Three-dimensional eye movements were measured simultaneously with both systems during fixation, saccades, optokinetic stimulation, and vestibular stimulation. Comparison of fixation positions between -15 degrees and +15 degrees showed that horizontal and vertical eye position signals of the two systems were highly correlated (R2 = 0.99). Torsion values measured by coils and the video system were significantly different (P < 0.001). Saccade main sequence parameters of coil and video signals were in good agreement. Gains of torsion in response to optokinetic stimulation (cycloversion and cyclovergence) were not significantly different (P > 0.05). Gain values of the vestibulo-ocular reflex as determined from coil and video signals showed good agreement for rotations. However, there was more variability in the video signals for translations, possibly due to relative motion between the head and cameras. Lower time resolution, possible instability of the head device of the video system, and inherent small instabilities of pupil tracking algorithms make the coil system the best choice when measuring eye movement responses with high precision or when involving high-frequency head motion. For less demanding and for static tests and measurements longer than a half an hour, the latest generation infrared video system is a good alternative to scleral search coils. However, the quality of torsion of the infrared video system is less compared with scleral search coils and needs further technological improvement.

The influence of walking speed on kinetic and kinematic parameters in patients with osteoarthritis of the hip using a force-instrumented treadmill and standardised gait speeds.

It is difficult to identify objective parameters for assessing the joint function when dealing with the evaluation of orthopaedic procedures, especially endoprosthetic hip replacement. Clinical gait analysis enables parameters of force and movement to be quantified. However, the influence of gait speed on these parameters has hardly been taken into consideration so far. The objective of the present study was therefore to investigate the effect of gait speed on gait parameters and to simplify the clinical conditions in patients with osteoarthritis of the hip by determining a standardised gait speed. A total of 28 patients with severe unilateral osteoarthritis of the hip were investigated at different gait speeds. The gait analysis equipment used consisted of an infinitely adjustable treadmill with force plates and an infrared video system. A special control mechanism permitted adjustment of the treadmill speed to a patient's self-determined pace. The mean gait speed of all patients with osteoarthritis of the hip was set at 2.20 km/h (0.61 m/s). Eight of the 10 gait parameters assessed increased significantly with changing gait speed. Pathological changes in gait patterns were found at the three gait speeds investigated, with the changes more accentuated at higher speeds. Dependence of gait parameters on gait speed could be concluded for a group of patients and for control subjects. Use of a force-instrumented treadmill is necessary for the setting of a standard gait speed, which should be set as high as achievable by patients without inducing pain and problems of coordination or balance. With the usage of standardised speeds, clinical gait analysis becomes easier to perform. Furthermore, one can assess the expected biomechanical advantages of newer prostheses, thus providing the surgeon with a basis for further decisions.

Resource distribution and surface activity of adult Lumbricus terrestris L. in an experimental system : The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Lumbricus terrestris L. is noted for activities on the soil surface and descriptions of feeding, movement and mating have previously been recorded. The aim of this study was to investigate the effects of resource availability on these behaviours using an experimental system. The laboratory set-up consisted of an arena with a continuous area of 1 m 2 with soil-filled tubes to a depth of 1 m. Eighteen mature, field-collected L. terrestris were used and fed with dried barley straw on the soil surface, either evenly or in one patch. Both patterns were applied twice over an experimental period of 56 days. An infrared video system was used to provide permanent records of a 12:12 hrs dark : light cycle. Earthworm behaviour was classified into three major groups; foraging/exploration, over-surface movements and mating, with time spent in each activity recorded for all individuals. Seventeen earthworms survived to the end of the experimental period. Surface activity peaked one hour after darkness and diminished steadily until lights up. Foraging activity increased by a factor of 1.6 in a resource-rich area whereas away from the patch it reduced by a factor of 0.8 compared with even straw distribution. Over-surface movement increased by a factor of nine after provision of a patchy straw distribution, with two thirds of movements initiated by individuals in a resource poor area. The majority of matings occurred early in the dark period. During even resource distribution, matings occurred equally in different parts of the arena whereas under patchy distribution, more matings were recorded in the resource-rich area. Presented results suggest that resource availability is an important factor affecting different aspects of surface behaviour in L terrestris .

Resource distribution and surface activity of adult Lumbricus terrestris L. in an experimental systemThe 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Lumbricus terrestris L. is noted for activities on the soil surface and descriptions of feeding, movement and mating have previously been recorded. The aim of this study was to investigate the effects of resource availability on these behaviours using an experimental system. The laboratory set-up consisted of an arena with a continuous area of 1 m 2 with soil-filled tubes to a depth of 1 m. Eighteen mature, field-collected L. terrestris were used and fed with dried barley straw on the soil surface, either evenly or in one patch. Both patterns were applied twice over an experimental period of 56 days. An infrared video system was used to provide permanent records of a 12:12 hrs dark : light cycle. Earthworm behaviour was classified into three major groups; foraging/exploration, over-surface movements and mating, with time spent in each activity recorded for all individuals. Seventeen earthworms survived to the end of the experimental period. Surface activity peaked one hour after darkness and diminished steadily until lights up. Foraging activity increased by a factor of 1.6 in a resource-rich area whereas away from the patch it reduced by a factor of 0.8 compared with even straw distribution. Over-surface movement increased by a factor of nine after provision of a patchy straw distribution, with two thirds of movements initiated by individuals in a resource poor area. The majority of matings occurred early in the dark period. During even resource distribution, matings occurred equally in different parts of the arena whereas under patchy distribution, more matings were recorded in the resource-rich area. Presented results suggest that resource availability is an important factor affecting different aspects of surface behaviour in L terrestris .

Comparison of scotopic pupil measurement with slitlamp-based cobalt blue light and infrared video-based system

Purpose To determine the accuracy and reproducibility of scotopic pupil measurements with a slitlamp-based cobalt blue light. Setting University of Texas Health Science Center−San Antonio, San Antonio, Texas, USA. Methods In a prospective experimental study, 2 independent observers measured 16 subjects’ pupils with a standard slitlamp-based cobalt blue light. In the same setting, the accuracy and reproducibility of the measurements were compared with those obtained with an infrared video-based system. Results Measurements of pupil size using the infrared video−computer system were highly reproducible. With the slitlamp-based cobalt blue light, the 2 measurements obtained by observer 2 (n = 16) were very close to each other (mean difference 0.09 mm ± 0.23 [SD]; P = .12), whereas those obtained by observer 1 (n = 16) were slightly different from each other (mean difference 0.18 ± 0.33 mm; P = .043). The mean pupil diameter measured with cobalt blue light was not significantly different between the 2 observers ( P > .05), and the measurements were highly correlated with each other ( r = 0.96, P < .01). The mean difference between the measurements using cobalt blue light and the infrared video−computer system was 0.21 ± 0.54 mm for observer 1 ( P = .47) and 0.06 ± 0.47 mm for observer 2 ( P = .85). Good correlation was noted between the measurements taken from each measuring device for both observers ( r = 0.87 and 0.90, P < .01). Conclusion Slitlamp-based cobalt blue light provided a reasonably good measurement of scotopic pupil size. It correlated well with the infrared video system when used at the lowest setting by experienced personnel. However, the observed difference between the measurements obtained by the 2 devices indicates that the cobalt blue light should be used cautiously in the refractive surgery preoperative evaluation of patients with large pupils.

Scleral search coils influence saccade dynamics.

The scleral search coil technique is commonly used for recording eye movements. The goal of this paper is to investigate to what extent the placement of scleral search coils onto the eyes influences the kinematics of saccades. To that end saccadic eye movements of human subjects were recorded with an infrared video system, while they wore coils and we compared the main sequence properties with recordings in which no coils were mounted on the eyes. It was found that saccades last longer (by about 8%) and become slower (by about 5%) when both eyes wear coils. This is truly due to the fact that the coils are on the eyes and not due to other factors that are part of this method, such as the scleral anesthesia. The influence of coils in both eyes was also observed when one coil was mounted on one eye only. Therefore the effect that the coils have on the eye movements cannot be attributed to purely mechanical factors, such as inertial load on the eyeball or increased friction. Rather the coils appear to change the oculomotor command signals that drive the saccadic eye movements.

Baseline respiration and spontaneous activity of sluggish marine tropical fish of the family Scorpaenidae

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 219:229-239 (2001) - doi:10.3354/meps219229 Baseline respiration and spontaneous activity of sluggish marine tropical fish of the family Scorpaenidae Christopher Zimmermann1,2,*, Andreas Kunzmann1,3 1Institut für Polarökologie der Universität Kiel, Wischhofstr. 1-3, Geb. 12, 24148 Kiel, Germany 2Institut für Seefischerei, Bundesforschungsanstalt für Fischerei, Palmaille 9, 22767 Hamburg, Germany 3Zentrum für Marine Tropenökologie, Universität Bremen, Fahrenheitstr. 6, 28359 Bremen, Germany *E-mail: czimmermann@ipoe.uni-kiel.de ABSTRACT: Baseline respiration and spontaneous activity were determined simultaneously for 6 specimens of tropical scorpionfishes, belonging to 2 different genera: Scorpaenopsis oxycephalus and S. diabolus (false stonefish) and Parascorpaena sp. and P. aurita. The experiments were conducted in an intermittent-flow respirometer at 24°C, at ambient light regime (12 h dark: 12 h light) and salinity (S = 32). Permanent measurements of fish activity by an infrared video system (number of movements) and oxygen consumption were coupled allowing the calculation of a standard oxygen consumption (SOC) rate. The experimental set-up allowed quantification of spontaneous activity. Relative SOC values varied between 32.3 mg O2 h-1 kg-1 wet mass (wm) for a large S. oxycephalus (82 g WM) and 68.9 mg O2 h-1 kg-1 WM for the smallest investigated specimen, a P. aurita (16 g WM). The latter also showed the highest spontaneous activity rate (mean 98 movements h-1; max.: 870 h-1), while the values for the most sluggish individual did not exceed 24.6 h-1 (mean) and 480 h-1 (max.), respectively. Absolute SOC for a standard mass of 50 g was calculated to be 2.0 mg O2 h-1, using a wet mass versus oxygen consumption relationship of SOC (mg O2 h-1) = 0.26 x WM(g)0.527. The tropical scorpionfish investigated are some of the most sluggish fish found on coral reefs, with activity levels (means and variance) similar to that of boreal or polar scorpaenids (e.g. sculpins). In this respect, there was no indication for any specific adaptation to temperature. Baseline oxygen consumption values of the fish in this study were the lowest recorded for marine tropical species, and a first rough comparison of the resting metabolism of scorpaenid fish over a wide range of environmental temperatures might indicate a reduced thermal sensitivity of the tropical fish investigated. KEY WORDS: Respiration · Standard oxygen consumption · Spontaneous activity · Coral reefs · Scorpionfishes · Scorpaenidae Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 219. Online publication date: September 10, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

Kinematic, Aerodynamic and Anatomical Mechanisms in the Slow, Maneuvering Flight of Pigeons

ABSTRACT A high-speed (200 Hz) infrared video system was used in a three-dimensional analysis of pigeon wing and body kinematics to determine the aerodynamic and anatomical mechanisms they use to produce force asymmetries to effect a turn during slow (3 m s−1) flight. Contrary to our expectations, pigeons used downstroke velocity asymmetries, rather than angle of attack or surface area asymmetries, to produce the disparities in force needed for directional changes. To produce a bank, a velocity asymmetry is created early in the downstroke and, in the majority of cases, then reversed at the end of the same downstroke, thus arresting the rolling angular momentum. When the velocity asymmetry was not reversed at the end of downstroke, the arresting force asymmetry was produced during upstroke, with velocity asymmetries creating disparate drag forces on the wings. Rather than using subtle aerodynamic variables to produce subtle downstroke force asymmetries, pigeons constantly adjust their position using a series of large alternating and opposing forces during downstroke and upstroke. Thus, a pigeon creates a precise ‘average’ body position (e.g. bank angle) and flight path by producing a series of rapidly oscillating movements. Although the primary locomotor event (downstroke) is saltatory, maneuvering during slow flight should be considered as a product of nearly continuous, juxtaposed force generation throughout the wingbeat cycle. Further, viewing upstroke as more than stereotypical, symmetrical wing recovery alters the evolutionary and functional context of investigations into the musculoskeletal mechanisms and the associated neural control involved in this unique kinematic event.

垂直半規管刺激性回転後眼振 健常耳での外側半規管刺激との比較

To test vertical semicircular canal function, we developed a new and convenient type of rotation-chair, in which subjects sat with their heads and backs tilting backward 60°and with their heads rolling laterally 45°. A CCD camera and infrared video system was used to record eye movement in the dark. Normal subjects were rotated with an acceleration of 2°/sec2 until the angular velocity reached 60°/sec. The rotation was then stopped with a deceleration of 100°/sec2 after per-rotation nystagmus subsided. The maximal slow phase eye velocity (MSPEV) of vertical components of vertical semicircular canal (VSCC)-induced post-rotatory nystagmus (PRN) were analysed.Subjects were first rotated with laterally rolling head angles of 30°, 45° and 60°to examine the optimal angle for stimulating VSCC.MSPEV of posterior semicircular canal (PSCC)-induced PRN was largest with a head angle of 60°. While MSPEV of anterior semicircular canal (ASCC)-induced PRN did not vary with the laterally rolling head angle. MSPEV of the vertical components of VSCC-induced PRN was then compared with that of the horizontal components of lateral semicircular canal (LSCC)-induced PRN. MSPEV of both PSCC- and ASCC-induced PRN were significantly smaller than that of LSCC-induced PRN.MSPEV of ASCC-induced PRN was slightly smaller than that of PSCC-induced PRN, though individual differences varied widely. However, there were very small leftright differences in MSPEV of both PSCC- and ASCC-induced PRN. Therefore, it is suggested that our PRN function test involving VSCC can diagnose vestibular diseases.

Absence of adaptive plasticity after voluntary vergence and accommodation

Subjects maintained their eyes crossed (verged) for a period of 8 min in darkness with monitoring provided by an infrared video system. Changes in resting vergence (RV) and resting focus (RF) were examined. Results showed: (i) visual stimulation was not necessary for adaptation of either RV or RF, but (ii) these purely motor effects were significantly smaller and more dissipative than those attributable to visually driven adaptation, and (iii) voluntary vergence amplitude was negatively correlated with pupil size. Assuming that voluntary vergence is driven by accommodation, then the voluntary signal must enter the oculomotor control system prior to the cross links between channels, but beyond the site of the visually driven adaptive elements.

Effects of optical pitch on oculomotor control and the perception of target elevation.

In two experiments, we used an ISCAN infrared video system to examine the influence of a pitched visual array on gaze elevation and on judgments of visually perceived eye level. In Experiment 1, subjects attempted to direct their gaze to a relaxed or to a horizontal orientation while they were seated in a room whose walls were pitched at various angles with respect to gravity. Gaze elevation was biased in the direction in which the room was pitched. In Experiment 2, subjects looked into a small box that was pitched at various angles while they attempted simply to direct their gaze alone, or to direct their gaze and place a visual target at their apparent horizon. Both gaze elevation and target settings varied systematically with the pitch orientation of the box. Our results suggest that under these conditions, an optostatic response, of which the subject is unaware, is responsible for the changes in both gaze elevation and judgments of target elevation.

Detection of Cracks and Measurement of Stress Intensity Factors by Infrared Video System

Detection of Cracks and Measurement of Stress Intensity Factors by Infrared Video System