Showing papers on "Accommodation published in 2017"

Accommodation and comfort in head-mounted displays

Abstract: Head-mounted displays (HMDs) often cause discomfort and even nausea. Improving comfort is therefore one of the most significant challenges for the design of such systems. In this paper, we evaluate the effect of different HMD display configurations on discomfort. We do this by designing a device to measure human visual behavior and evaluate viewer comfort. In particular, we focus on one known source of discomfort: the vergence-accommodation (VA) conflict. The VA conflict is the difference between accommodative and vergence response. In HMDs the eyes accommodate to a fixed screen distance while they converge to the simulated distance of the object of interest, requiring the viewer to undo the neural coupling between the two responses. Several methods have been proposed to alleviate the VA conflict, including Depth-of-Field (DoF) rendering, focus-adjustable lenses, and monovision. However, no previous work has investigated whether these solutions actually drive accommodation to the distance of the simulated object. If they did, the VA conflict would disappear, and we expect comfort to improve. We design the first device that allows us to measure accommodation in HMDs, and we use it to obtain accommodation measurements and to conduct a discomfort study. The results of the first experiment demonstrate that only the focus-adjustable-lens design drives accommodation effectively, while other solutions do not drive accommodation to the simulated distance and thus do not resolve the VA conflict. The second experiment measures discomfort. The results validate that the focus-adjustable-lens design improves comfort significantly more than the other solutions.

Accommodation-invariant computational near-eye displays

Abstract: Although emerging virtual and augmented reality (VR/AR) systems can produce highly immersive experiences, they can also cause visual discomfort, eyestrain, and nausea. One of the sources of these symptoms is a mismatch between vergence and focus cues. In current VR/AR near-eye displays, a stereoscopic image pair drives the vergence state of the human visual system to arbitrary distances, but the accommodation, or focus, state of the eyes is optically driven towards a fixed distance. In this work, we introduce a new display technology, dubbed accommodation-invariant (AI) near-eye displays, to improve the consistency of depth cues in near-eye displays. Rather than producing correct focus cues, AI displays are optically engineered to produce visual stimuli that are invariant to the accommodation state of the eye. The accommodation system can then be driven by stereoscopic cues, and the mismatch between vergence and accommodation state of the eyes is significantly reduced. We validate the principle of operation of AI displays using a prototype display that allows for the accommodation state of users to be measured while they view visual stimuli using multiple different display modes.

Chromablur: rendering chromatic eye aberration improves accommodation and realism

Abstract: Computer-graphics engineers and vision scientists want to generate images that reproduce realistic depth-dependent blur. Current rendering algorithms take into account scene geometry, aperture size, and focal distance, and they produce photorealistic imagery as with a high-quality camera. But to create immersive experiences, rendering algorithms should aim instead for perceptual realism. In so doing, they should take into account the significant optical aberrations of the human eye. We developed a method that, by incorporating some of those aberrations, yields displayed images that produce retinal images much closer to the ones that occur in natural viewing. In particular, we create displayed images taking the eye's chromatic aberration into account. This produces different chromatic effects in the retinal image for objects farther or nearer than current focus. We call the method ChromaBlur. We conducted two experiments that illustrate the benefits of ChromaBlur. One showed that accommodation (eye focusing) is driven quite effectively when ChromaBlur is used and that accommodation is not driven at all when conventional methods are used. The second showed that perceived depth and realism are greater with imagery created by ChromaBlur than in imagery created conventionally. ChromaBlur can be coupled with focus-adjustable lenses and gaze tracking to reproduce the natural relationship between accommodation and blur in HMDs and other immersive devices. It may thereby minimize the adverse effects of vergence-accommodation conflicts.

Accommodation in Youth With OCD and Anxiety

Abstract: Accommodation refers to the ways in which family members act to alleviate a child's symptoms and distress. In the context of youth obsessive-compulsive disorder (OCD) and anxiety, accommodation may contribute to the development and maintenance of the disorder. We review the theory and research literature on accommodation, including measures of accommodation. Findings support the idea that accommodation is not a preferred parenting strategy; the sequelae of accommodation are negative and are often associated with both parent and sibling distress. Accommodation should be assessed and targeted in treatment for youth OCD and anxiety. We conclude by identifying several areas for future research, including the development of interventions that specifically target accommodation, the evaluation of potential family factors implicated in accommodation, and the exploration of the construct of accommodation in other childhood disorders.

The importance of destination attractiveness and entrepreneurial orientation in explaining firm performance in the Sardinian accommodation sector

Abstract: Purpose The purpose of this paper is to contribute to the understanding of successful business performance among accommodation firms by focusing on entrepreneurial orientation (EO) and destination attractiveness. Design/methodology/approach A web-based e-mail survey was undertaken in the Sardinian accommodation sector in 2012. The sample included 224 accommodation firms and analyses were performed using ordered logit regressions. Findings The results suggest no differential impact of EO on sales and profit depending on the attractiveness of the location in which the accommodation firm operates. Both EO and destination attractiveness were found to exert independent positive effects on firm performance. Furthermore, EO was found to have a larger effect on firm performance than destination attractiveness. Research limitations/implications The study mainly considered hotels and camping accommodations in Sardinia. Additional investigations across accommodation types and geographic contexts are needed. Practical implications The findings suggest that accommodation firms should focus on implementing entrepreneurial activities and not only, as frequently happens, concentrate on selecting attractive destinations in which to conduct their business. Moreover, the findings also suggest that accommodation firms that are located in less attractive areas may produce good performance if they are managed with an EO. Finally, training programs should be developed to improve the entrepreneurial abilities of accommodation managers. Originality/value The specific topics of this paper have been understudied. The findings hold practical implications for entrepreneurs and managers who are involved in the accommodation sector.

Achieving service recovery through responding to negative online reviews

Abstract: The beginning of the 21st century witnesses a trend for business and leisure travelers to make accommodation decisions by referring to online reviews of hotel accommodation services and the hotel m...

Linguistic Style Accommodation Shapes Impression Formation and Rapport in Computer-Mediated-Communication

Abstract: Communication accommodation theory predicts that social power plays an important role in influencing communicative behaviors. Previous research suggests these effects extend to linguistic style, th...

Is There a Downside of Job Accommodations? An Employee Perspective on Individual Change Processes.

Abstract: By modifying the work environments, work routines, and work tasks of employees with health restrictions, organizations can effectively help them continue to perform their jobs successfully. As such, job accommodations are an effective tool to secure the continued employment of aging workers who develop disabilities across their life span. However, while accommodations tackle health-related performance problems, they might create new challenges on the part of the affected employee. Building on the organizational change and accommodations literatures, we propose a theoretical framework of negative experiences during accommodation processes and apply it to qualitative data from group interviews with 73 manufacturing workers at a German industrial company who were part of the company's job accommodation program. Although problems associated with health-related impairments were mostly solved by accommodation, affected employees with disabilities reported about interpersonal problems and conflicts similar to those that typically occur during organizational change. Lack of social support as well as poor communication and information were raised as criticisms. Furthermore, our findings indicate that discrimination, bullying, and maltreatment appear to be common during accommodation processes. To make accommodation processes more successful, we derive recommendations from the organizational change literature and apply it to the accommodation context. We also emphasize unique characteristics of the accommodation setting and translate these into practical implications.

Pharmacological and physiological manipulation of ocular accommodation

Abstract: The primary aim of this thesis was to investigate in-vivo changes to ocular morphology during ocular accommodation, with particular attention to ciliary muscle changes, using pharmacological agents and physiological stimuli. To determine the optimum target for accommodation studies, accommodative responses to different stimuli were investigated. Insignificant differences in accommodative responses to a letter target and Maltese cross were found. Anterior Segment Optical Coherence Tomography (AS-OCT) and semi-automated software were used for in-vivo investigation of ciliary muscle morphology. As expected, anti-muscarinic agents reduced the accommodative amplitude, the greatest effect evident with cyclopentolate hydrochloride 1%, which was, in turn, associated with a reduced forward movement of the ciliary muscle, possibly due to the restricted movement of radial and longitudinal fibres. Pilocarpine nitrate 2% induced a contractile shortening and anterior thickening of the ciliary muscle in both pre-presbyopic and presbyopic eyes. However, pilocarpine does not seem to be a super-stimulus for accommodation. Comparison between cyclopentolate and pilocarpine ciliary muscle morphology further supported the concept that anterior movement of ciliary muscle mass is essential to elicit higher accommodative amplitudes. Ciliary muscle asymmetry was identified between horizontal and vertical meridians. The findings confirmed a longer ciliary muscle in axial elongated eyes, however, only within the temporal, nasal, and superior muscle quadrants. Nevertheless, during accommodation, anterior thickening and contractile shortening of the muscle was evident for all four quadrants. The effect of accommodation on posterior eye conformation revealed a homogenous elongation of the posterior pole, with the greatest expansion occurring along the inferior-nasal quadrant, rather than the visual axis. The possibility of a vitreous role in accommodation is discussed. The studies presented herein suggest a forward movement of ciliary muscle mass is necessary for accommodation. Further research is required to establish whether a mechanical restriction occurs to the muscle with increasing age, resulting in presbyopia. Moreover, investigations are required to explore the variation in ciliary muscle morphology in eyes with ametropia, as well as the likely role of the vitreous in accommodation.

Operationalizing workplace accommodations for individuals with disabilities: A scoping review.

Abstract: Background The provision of workplace accommodations is a proven strategy in supporting individuals with disabilities at work. Accommodations include a wide range of supports and strategies that are not very well defined beyond the Americans with Disabilities Act in the United States. Understanding the landscape of accommodations is important to measure the impact of programs that support employment of individuals with disabilities. Objective To conduct a scoping review and thematic analysis of research literature to identify how workplace accommodations are operationalized and to identify knowledge gaps in its conceptualization. Methods Keywords searches were conducted in seven electronic databases. Title, abstract, and full text screening was conducted followed by a thematic analysis of the content to identify how workplace accommodations are operationalized. Results Overall, 47 studies were selected for review. 433 different types of accommodations were identified, of which assistive technology and specialized equipment represented the most frequently reported type of accommodation (40%). A very small percentage of studies included policy changes (9%) and human assistance (5%) as an accommodation strategy. Conclusions This scoping review aims to clarify how accommodations are operationalized in the research literature. Key knowledge gaps identified include the systematic exclusion of certain types of supports or disability types.

Small accommodation business growth : patterns, precedents and outcomes observed from rural Zhejiang province of China

Abstract: This thesis is protected by copyright, with all rights reserved. By reading and using the thesis, the reader understands and agrees to the following terms: 1. The reader will abide by the rules and legal ordinances governing copyright regarding the use of the thesis. 2. The reader will use the thesis for the purpose of research or private study only and not for distribution or further reproduction or any other purpose. 3. The reader agrees to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.

Measurement of static convergence and accommodation responses to images of integral photography and binocular stereoscopy

Abstract: Static convergence and accommodation responses were measured by comparing integral photography images, binocular stereoscopic images, and real objects in a measurement range from 450 to 900 mm. The experimental results were evaluated with a multiple comparison test. It was found that six of the ten observers did not have an accommodation-convergence conflict in viewing integral photography in the range. Moreover, the required resolution was found to be 0.7 or more and less than 1.4 cycles per degree for inducing accommodation. In conclusion, integral photography can provide a natural 3D image that looks like a real object.

Accommodation of the human lens capsule using a finite element model based on nonlinear regionally anisotropic biomembranes.

Abstract: Accommodation of the eyes, the mechanism that allows humans to focus their vision on near objects, naturally diminishes with age via presbyopia. People who have undergone cataract surgery, using current surgical methods and artificial lens implants, are also left without the ability to accommodate. The process of accommodation is generally well known; however the specific mechanical details have not been adequately explained due to difficulties and consequences of performing in vivo studies. Most studies have modeled the mechanics of accommodation under assumptions of a linearly elastic, isotropic, homogenous lens and lens capsule. Recent experimental and numerical studies showed that the lens capsule exhibits nonlinear elasticity and regional anisotropy. In this paper we present a numerical model of human accommodation using a membrane theory based finite element approach, incorporating recent findings on capsular properties. This study seeks to provide a novel perspective of the mechanics of accommodation. Such findings may prove significant in seeking biomedical solutions to restoring loss of visual power.

The interaction of pupil response with the vergence system

Abstract: A gaze shift from a target at distance to a target at near leads to pupillary constriction. The regulation of this pupillary near response is ill known. We investigated the impact of accommodation, convergence, and proximity on the pupillary diameter. We recorded pupil size and vergence eye movements with the use of an infrared eye tracker. We determined the pupillary response in four conditions: (1) after a gaze shift from far to near without accommodation, (2) after a gaze shift from far to near with neither accommodation nor convergence, (3) after accommodation alone, and (4) after accommodation with convergence without a gaze shift to near. These responses were compared to the pupil response of a full near response and to a gaze shift from one far target to another. We found a reliable pupillary near response. The removal of both accommodation and convergence in gaze shift from far to near abolished the pupillary near response. Accommodation alone did not induce pupillary constriction, while convergence and accommodation together induced a pupil response similar to the full near response. The main trigger for the pupillary response seems to be convergence. Neither accommodation nor proximity alone induce a significant pupillary constriction. This suggests that the miosis of the near triad is closely coupled to the vergence system rather than being independently regulated.

Variation of axial and oblique astigmatism with accommodation across the visual field.

Abstract: In this study we investigated the impact of accommodation on axial and oblique astigmatism along 12 meridians of the central 30° of visual field and explored the compensation of corneal first-surface astigmatism by the remainder of the eye's optical system. Our experimental evidence revealed no systematic effect of accommodation on either axial or oblique astigmatism for two adult populations (myopic and emmetropic eyes). Although a few subjects exhibited systematic changes in axial astigmatism during accommodation, the dioptric value of these changes was much smaller than the amount of accommodation. For most subjects, axial and oblique astigmatism of the whole eye are both less than for the cornea alone, which indicates a compensatory role for internal optics at all accommodative states in both central and peripheral vision. A new method for determining the eye's optical axis based on visual field maps of oblique astigmatism revealed that, on average, the optical axis is 4.8° temporal and 0.39° superior to the foveal line-of-sight in object space, which agrees with previous results obtained by different methodologies and implies that foveal astigmatism includes a small amount of oblique astigmatism (0.06 D on average). Customized optical models of each eye revealed that oblique astigmatism of the corneal first surface is negligible along the pupillary axis for emmetropic and myopic eyes. Individual variation in the eye's optical axis is due in part to misalignment of the corneal and internal components that is consistent with tilting of the crystalline lens relative to the pupillary axis.

Deep Equality as an Alternative to Accommodation and Tolerance

Abstract: The call to manage religious diversity from various sectors has produced a response that has largely been framed in terms of tolerance and accommodation. It has also produced an over-reliance on law and legal solutions and a tendency to look to top-down, or vertical, solutions rather than the ways in which difference and diversity are negotiated in everyday life. Based on a wide range of data that highlights the themes of respect and similarity, this article proposes the concept of deep equality as an alternative to accommodation and tolerance. The article concludes by reflecting on the objections to and limitations of such an approach, including the objection that focusing on positive narratives is naïve and a possible evolutionary human pre-disposition

Accommodation services for competitive tourism in Sub-Saharan Africa: Historical evidence from Malawi

Abstract: The accommodation services sector is a vital underpinning of the competitiveness of destinations in especially emerging tourism regions of the global economy. Within the environment of Africa building the competitiveness of countries as tourism destinations is inseparable from the challenge of establishing a network of different forms of accommodation at competitive prices and internationally acceptable quality standards. This paper uses a longitudinal approach to analyse the development of the accommodation services sector in one African country – Malawi – which is scaling up its tourism industry. Using historical evidence the objective is to examine the unfolding evolution of accommodation services as a factor in enhancing tourism destination competitiveness. The chequered pathway followed in Malawi to building the country’s network of hotels and small-scale accommodation establishments is traced from the colonial period to post-independence developments. It is argued that in understanding the historical evolution of accommodation services policy re-orientations have been significant drivers of change.

Optical mapping near-eye three-dimensional display with correct focus cues.

Abstract: We present an optical mapping near-eye (OMNI) three-dimensional display method for wearable devices. By dividing a display screen into different subpanels and optically mapping them to various depths, we create a multiplane volumetric image with correct focus cues for depth perception. The resultant system can drive the eye’s accommodation to the distance that is consistent with binocular stereopsis, thereby alleviating the vergence–accommodation conflict, the primary cause for eye fatigue and discomfort. Compared with the previous methods, the OMNI display offers prominent advantages in adaptability, image dynamic range, and refresh rate.

Peer-To-Peer Accommodation: Drivers and User Profiles

Abstract: The tourism industry is currently dealing with the impacts of collaborative consumption, with tourists increasingly using peer-to-peer (P2P) services such as Airbnb and Uber. This study aims to extend our knowledge of why P2P accommodation services are not just succeeding, but thriving, from the consumer perspective, and it contributes to an understanding of the reasons for the popularity of P2P accommodation services and how consumer heterogeneity affects consumer choices. In this study, the drivers of P2P accommodation services are examined in order to better understand consumer characteristics and behaviour. Based on a survey of Internet users in Finland, the major drivers affecting the use of P2P accommodation services are the age of consumers, active use of the Internet and online technologies, and the frequency of international travel. Cluster analysis identified two user profiles corresponding to consumer motivations for using P2P accommodation services. The first consumer group uses P2P accommodation services to make their trips more convenient, while the second uses them mostly for social reasons.

The decision-making process of and the decisive factors in accommodation choice

Abstract: This study examines tourists’ decision-making process of and highlights the decisive factors in accommodation choice, employing the discrete choice (multinomial logit and nested logit) models and using the international tourist data of Taiwan. The results of this study may be indicative of the hierarchical nature of tourists’ decision-making process of accommodation choice. In addition, we find that price is a significant factor in accommodation choice, whereas income has only limited explanatory power. The results also indicate that tourists with a longer length of stay tend to choose hotels of lower quality, and, in contrast, elder people prefer better accommodations.

Adaptive Optics for Autofocusing Eyeglasses

Abstract: Over 1 billion people worldwide including more than 100 million people in the United States of America alone suffer from an age-related eye condition known as presbyopia. Presbyopia is caused by a loss of focal accommodation of the crystalline lens inside the eye as the lens stiffens with age. A presbyopic person has reduced or very limited ability to focus on objects placed at different distances. The utilization of conventional fixed, uniform or graded power eyeglasses for presbyopia correction is generally unsatisfactory as fixed power eyepieces cannot provide any accommodation restoration. In this paper we will discuss an implementation of lightweight adaptive-optics auto-focusing eyeglasses that augment the accommodation range of vision thus partially or fully cancelling the accommodation loss caused by presbyopia and restoring normal vision function.

Assessing the accommodation response after near visual tasks using different handheld electronic devices

Abstract: Purpose: To assess the accommodation response after short reading periods using a tablet and a smartphone as well as determine potential differences in the accommodation response at various stimulus vergences using a Hartmann- Shack aberrometer. Methods: Eighteen healthy subjects with astigmatism of less than 1 D, corrected visual acuity of 20/20 or better, and normal findings in an ophthalmic examination were enrolled. Accommodation responses were obtained under three different conditions: accommodation system of the eye relaxed and visually stressed with a tablet and an smartphone for 10 min, at a distance of 0.25 m from the subject's eyes. Three measurements of accommodation response were monocularly acquired at stimulus vergences ranging from 0 to 4 D (1-D step). Results: No statistically significant differences were found in the accommodation responses among the conditions. A moderate but gradually increasing root mean square, coma-like aberration was found for every condition. Conversely, the spherical aberration decreased as stimulus vergences increased. These outcomes were identified in comparison to the one-to-one ideal accommodation response, implying that a certain lag value was present in all stimulus vergences different from 0 D. Conclusions: The results support the hypothesis that the difference between the ideal and real accommodation responses is mainly attributed to parameters associated with the accommodation process, such as the near visual acuity, depth of focus, pupil diameter, and wavefront aberrations. The wavefront aberrations were dependent on the 3-mm pupil size selected in this study. The accommoda tion response was not dependent on the electronic device employed in each condition, and it was mainly associated with young age and level of amplitude of accommodation of the subjects.

Accommodation based optical correction

Abstract: An auto-focus head-mounted display (HMD) dynamically generates aberration-adjusted images based on measured accommodation of user's eye(s). An aberration-adjusted image is an image distorted to correct aberrations that would otherwise occur at a retina of the user due to image light passing through optics of the HMD. The aberration-adjusted image corrects the aberrations of the HMD and “accounts” for the aberrations of the eye so that the resulting retinal image is free of optical aberrations due to the HMD but preserves correct eye optical aberrations that are correlated with a current accommodative state of the eye.

Multilingual Accommodation in Namibia: An Examination of Six Ethnolinguistic Groups’ Language Use in Intra- and Intergroup Interactions

Abstract: This study examined how six different ethnolinguistic groups in Windhoek, capital of Namibia, adjust their language use during intergroup encounters. Invoking communication accommodation theory, we...