The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Eli Peli - One of the best experts on this subject based on the ideXlab platform.
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high prevalence of strabismic visual Field Expansion in pediatric homonymous hemianopia
PLOS ONE, 2018Co-Authors: Matthew P Bronstad, Eli Peli, Rui Liu, Amy Doherty, Anne B FultonAbstract:If homonymous hemianopia develops in childhood it is frequently accompanied by strabismus. In some of these cases the strabismus increases the size of the binocular visual Field. We determined how prevalent visual-Field-expanding strabismus is in children who have homonymous hemianopia. Medical records were examined from 103 hemianopic patients with exotropia (XT) or esotropia (ET). For each participant, we determined whether their strabismus was in a direction that resulted in visual Field Expansion (i.e. left exotropia with left homonymous hemianopia). Ages at which hemianopia and strabismus were first noted were compared to determine which developed first. The prevalence of XT (24%) and ET (9%) with homonymous hemianopia were both much higher than in the general population (1.5% and 5%, respectively). More strabismic eyes pointed to the blind than seeing side (62 vs 41, 60% vs. 40%, p = 0.02). Exotropic eyes were five times more likely to point to the blind side than esotropic eyes (85% vs 15%). Strabismus, especially exotropia, is much more common in pediatric homonymous hemianopia than in the general population. The strabismus is significantly more often in a visual Field-expanding direction. These results support an adaptive role for the strabismus. Patients with HH and exotropia or esotropia should be aware that their visual Field could be reduced by strabismus surgery.
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the risk of pedestrian collisions with peripheral visual Field loss
Journal of Vision, 2016Co-Authors: Eli Peli, Henry L. Apfelbaum, Eliot L Berson, Robert B GoldsteinAbstract:Patients with peripheral Field loss complain of colliding with other pedestrians in open-space environments such as shopping malls. Field Expansion devices (e.g., prisms) can create artificial peripheral islands of vision. We investigated the visual angle at which these islands can be most effective for avoiding pedestrian collisions, by modeling the collision risk density as a function of bearing angle of pedestrians relative to the patient. Pedestrians at all possible locations were assumed to be moving in all directions with equal probability within a reasonable range of walking speeds. The risk density was found to be highly anisotropic. It peaked at ≈45° eccentricity. Increasing pedestrian speed range shifted the risk to higher eccentricities. The risk density is independent of time to collision. The model results were compared to the binocular residual peripheral island locations of 42 patients with forms of retinitis pigmentosa. The natural residual island prevalence also peaked nasally at about 45° but temporally at about 75°. This asymmetry resulted in a complementary coverage of the binocular Field of view. Natural residual binocular island eccentricities seem well matched to the collision-risk density function, optimizing detection of other walking pedestrians (nasally) and of faster hazards (temporally). Field Expansion prism devices will be most effective if they can create artificial peripheral islands at about 45° eccentricities. The collision risk and residual island findings raise interesting questions about normal visual development.
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considering apical scotomas confusion and diplopia when prescribing prisms for homonymous hemianopia
Translational Vision Science & Technology, 2013Co-Authors: Henry L. Apfelbaum, Alex R Bowers, Eli Peli, Nicole C RossAbstract:Purpose: While prisms are commonly prescribed for homonymous hemianopia to extend or expand the visual Field, they cause potentially troubling visual side effects, including nonveridical location of perceived images, diplopia, and visual confusion. In addition, the Field behind a prism at its apex is lost to an apical scotoma equal in magnitude to the amount of prism shift. The perceptual consequences of apical scotomas and the other effects of various designs were examined to consider parameters and designs that can mitigate the impact of these effects. Methods: Various configurations of sector and peripheral prisms were analyzed, in various directions of gaze, and their visual effects were illustrated using simulated perimetry. A novel ‘‘percept’’ diagram was developed that yielded insights into the patient’s view through the prisms. The predictions were verified perimetrically with patients. Results: The diagrams distinguish between potentially beneficial Field Expansion via visual confusion and the pericentrally disturbing and useless effect of diplopia, and their relationship to prism power and gaze direction. They also illustrate the nonexpanding substitution of Field segments of some popular prism designs. Conclusions: Yoked sector prisms have no effect at primary gaze or when gaze is directed toward the seeing hemiField, and they introduce pericentral Field loss when gaze is shifted into them. When fitted unilaterally, sector prisms also have an effect only when the gaze is directed into the prism and may cause a pericentral scotoma and/or central diplopia. Peripheral prisms are effective at essentially all gaze angles. Since gaze is not directed into them, they avoid problematic pericentral effects. We derive useful recommendations for prism power and position parameters, including novel ways of fitting prisms asymmetrically. Translational Relevance: Clinicians will find these novel diagrams, diagramming techniques, and analyses valuable when prescribing prismatic aids for hemianopia and when designing new prism devices for patients with various types of Field loss.
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extended wearing trial of triField lens device for tunnel vision
Ophthalmic and Physiological Optics, 2010Co-Authors: Russell L Woods, Robert G Giorgi, Eliot L Berson, Eli PeliAbstract:Severe visual Field constriction (tunnel vision) impairs the ability to navigate and walk safely. We evaluated TriField glasses as a mobility rehabilitation device for tunnel vision in an extended wearing trial. Twelve patients with tunnel vision (5‐22� wide) due to retinitis pigmentosa or choroideremia participated in the 5-visit wearing trial. To expand the horizontal visual Field, one spectacle lens was fitted with two apex-to-apex prisms that vertically bisected the pupil on primary gaze. This provides visual Field Expansion at the expense of visual confusion (two objects with the same visual direction). Patients were asked to wear these spectacles as much as possible for the duration of the wearing trial (median 8, range 6‐60 weeks). Clinical success (continued wear, indicating perceived overall benefit), visual Field Expansion, perceived direction and perceived visual ability were measured. Of 12 patients, nine chose to continue wearing the TriField glasses at the end of the wearing trial. Of those nine patients, at long-term follow-up (35‐78 weeks), three reported still wearing the TriField glasses. Visual Field Expansion (median 18, range 9‐38� ) was demonstrated for all patients. No patient demonstrated adaptation to the change in visual direction produced by the TriField glasses (prisms). For reported difficulty with obstacles, some differences between successful and non-successful wearers were found. TriField glasses provided reported benefits in obstacle avoidance to 7 of the 12 patients completing the wearing trial. Crowded environments were particularly difficult for most wearers. Possible reasons for long-term discontinuation and lack of adaptation to perceived direction are discussed.
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development and evaluation of vision multiplexing devices for vision impairments
International Journal on Artificial Intelligence Tools, 2009Co-Authors: Eli Peli, Alex R Bowers, Gang Luo, Noa M RensingAbstract:We have proposed a novel concept of vision multiplexing for the visually impaired – superimposing contour images over their natural view of a scene or over original images presented on a TV screen. We have implemented the concept using an optical see-through head mounted display to provide either visual Field Expansion to patients with peripheral Field loss or vision enhancement to patients with central vision loss. We have also implemented the concept in a video player with dynamic magnification for patients with central vision loss. Results of initial testing in the lab and on the street are promising.
David A B Miller - One of the best experts on this subject based on the ideXlab platform.
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systematic photonic crystal device design global and local optimization and sensitivity analysis
IEEE Journal of Quantum Electronics, 2006Co-Authors: Yang Jiao, Shanhui Fan, David A B MillerAbstract:We present a set of modeling, sensitivity analysis, and design optimization methods for photonic crystal structures based on Wannier basis Field Expansion and efficient matrix analysis techniques. We develop the sensitivity analysis technique to analyze both refractive index perturbations and dielectric boundary shift perturbations. Our modeling method is /spl sim/1000/spl times/ faster than finite-difference time-domain (FDTD) for searching through a large number of similar device designs. We show that our optimization techniques, relying on the efficiency of the modeling and sensitivity analysis methods, enable systematic global and local optimizations of integrated optical components. We show that our design method can be controlled to favor designs without high-energy build-ups, potentially making them more fabrication-error tolerant. We present design examples and verify our designs with FDTD calculations.
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demonstration of systematic photonic crystal device design and optimization by low rank adjustments an extremely compact mode separator
Optics Letters, 2005Co-Authors: Yang Jiao, Shanhui Fan, David A B MillerAbstract:We present a powerful design and optimization method for devices in a photonic crystal. The method is based on a Wannier basis Field Expansion and efficient matrix analysis techniques for searching through a vast number of designs. The method permits the design of many compact optical devices with complex and novel functions. We present a design example of a very compact mode separator that is 8.2 µm×13.3 µm in size that demultiplexes the three modes of an input photonic crystal multimode waveguide into three single-mode output waveguides. We verify the method with finite-difference time-domain calculations.
David L Hill - One of the best experts on this subject based on the ideXlab platform.
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modifications of gustatory nerve synapses onto nucleus of the solitary tract neurons induced by dietary sodium restriction during development
The Journal of Comparative Neurology, 2008Co-Authors: Olivia L May, Alev Erisir, David L HillAbstract:The terminal Fields of nerves carrying gustatory information to the rat brainstem show a remarkable amount of Expansion in the nucleus of the solitary tract (NTS) as a result of early dietary sodium restriction. However, the extent to which these axonal changes represent corresponding changes in synapses is not known. To identify the synaptic characteristics that accompany the terminal Field Expansion, the greater superficial petrosal (GSP), chorda tympani (CT), and glossopharyngeal (IX) nerves were labeled in rats fed a sodium-restricted diet during pre- and postnatal development. The morphology of these nerve terminals within the NTS region where the terminal Fields of all three nerves overlap was evaluated by transmission electron microscopy. Compared to data from control rats, CT axons were the most profoundly affected. The density of CT arbors and synapses quadrupled as a result of the near life-long dietary manipulation. In contrast, axon and synapse densities of GSP and IX nerves were not modified in sodium-restricted rats. Furthermore, compared to controls, CT terminals displayed more instances of contacts with postsynaptic dendritic protrusions and IX terminals synapsed more frequently with dendritic shafts. Thus, dietary sodium restriction throughout pre- and postnatal development had differential effects on the synaptic organization of the three nerves in the NTS. These anatomical changes may underlie the impact of sensory restriction during development on the functional processing of taste information and taste-related behaviors.
Shuwen Zhang - One of the best experts on this subject based on the ideXlab platform.
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land surface temperature response to irrigated paddy Field Expansion a case study of semi arid western jilin province china
Scientific Reports, 2019Co-Authors: Tingxiang Liu, Shuwen ZhangAbstract:The irrigated paddy Fields have expanded greatly at semi-arid western Jilin province of China in recent over ten years, the sources of which are rain-fed cornFields, swamp meadow and saline alkali land mainly. Based on regional land use data, remote sensing data and meteorological data, this paper evaluates the land surface temperature changes response to land surface biophysical processes changes resulting from land use change (LUC), and dissociates the effect of radiative change (albedo) and non-radiative change (evapotranspiration and turbulent process) quantitatively using the energy redistribution factor. The results show that, the total land surface temperature changes based on energy redistribution factor are consistent with that based on remote sensing data on the whole, which have significant and different seasonal variations for agriculture adjustment of rain-fed cornFields to irrigated paddy Fields and nature land reclamation. Generally, the largest Land surface temperature changes (ΔTs) are most pronounced in May and June for agriculture adjustment of rain-fed cornFields to irrigated paddy Fields, which is −1.85 K averagely. Notable decline of albedo from saline alkali land to irrigated paddy Fields in April to June greatly counteracts the cooling effect of non-radiative processes changes, while the largest ΔTs is found of −2. 54 K in dry summer months of July and August. For swamp meadows to irrigated paddy Fields, non-radiative process is strengthened from June to September, the cooling effect of which is −1.69 K averagely. This study provides a case reference of local temperature change and obvious changes of land surface non-radiative terms at semi-arid area for adjustment of agricultural activities and land use changes.
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paddy Field Expansion and aggregation since the mid 1950s in a cold region and its possible causes
Remote Sensing, 2018Co-Authors: Fengqin Yan, Chaobin Yang, Shuwen ZhangAbstract:Over the last six decades, paddy Fields on the Sanjiang Plain have experienced rapid Expansion and aggregation. In our study, land use and land cover changes related to paddy Fields were studied based on information acquired from topographic maps and remote-sensing images. Paddy Field Expansion and aggregation were investigated through landscape indices and trajectory codes. Furthermore, the possible causes of paddy Field Expansion and aggregation were explored. Results indicated that such Fields have increased by approximately 42,704 ha·y−1 over the past six decades. Approximately 98% of paddy Fields in 2015 were converted from other land use types. In general, the gravity center moved 254.51 km toward the northeast, at a rate of approximately 4.17 km·y−1. The cohesion index increased from 96.8208 in 1954 to 99.5656 in 2015, and the aggregation index grew from 91.3533 in 1954 to 93.4448 in 2015, indicating the apparent aggregation of paddy Fields on the Sanjiang Plain. Trajectory analyses showed that the transformations from marsh as well as from grassland to dry farmland and then into paddy Fields were predominant. Climate warming provided a favorable environment for rice planting. Meanwhile, population growth, technological progress, and government policies drove paddy Field Expansion and aggregation during the study period.
Yang Jiao - One of the best experts on this subject based on the ideXlab platform.
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systematic photonic crystal device design global and local optimization and sensitivity analysis
IEEE Journal of Quantum Electronics, 2006Co-Authors: Yang Jiao, Shanhui Fan, David A B MillerAbstract:We present a set of modeling, sensitivity analysis, and design optimization methods for photonic crystal structures based on Wannier basis Field Expansion and efficient matrix analysis techniques. We develop the sensitivity analysis technique to analyze both refractive index perturbations and dielectric boundary shift perturbations. Our modeling method is /spl sim/1000/spl times/ faster than finite-difference time-domain (FDTD) for searching through a large number of similar device designs. We show that our optimization techniques, relying on the efficiency of the modeling and sensitivity analysis methods, enable systematic global and local optimizations of integrated optical components. We show that our design method can be controlled to favor designs without high-energy build-ups, potentially making them more fabrication-error tolerant. We present design examples and verify our designs with FDTD calculations.
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demonstration of systematic photonic crystal device design and optimization by low rank adjustments an extremely compact mode separator
Optics Letters, 2005Co-Authors: Yang Jiao, Shanhui Fan, David A B MillerAbstract:We present a powerful design and optimization method for devices in a photonic crystal. The method is based on a Wannier basis Field Expansion and efficient matrix analysis techniques for searching through a vast number of designs. The method permits the design of many compact optical devices with complex and novel functions. We present a design example of a very compact mode separator that is 8.2 µm×13.3 µm in size that demultiplexes the three modes of an input photonic crystal multimode waveguide into three single-mode output waveguides. We verify the method with finite-difference time-domain calculations.