Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Distance”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources
PubMed1999

Seven years on: distance learning courses for first level registered nurses and midwives.

There is a recognized need to increase the accessibility and flexibility of post-registration course provision for first level registered nurses and midwives. Distance learning courses were developed and implemented at the University of Dundee in response to this need. The courses provide a range of learning opportunities from single module certificate courses to Bachelor, Honours and Masters level studies. The courses are well received by nurses and midwives and experience, over the last 7 years, has highlighted important aspects for distance learning education for both professional groups. Different educational strategies such as Work-based Learning and Problem-based Learning are incorporated into distance learning course design to facilitate the integration of theory and practice and develop cognitive and meta-cognitive skills. The relationship between course assessment and clinical environment is also a key feature of course design, with assessment methods built around work-based learning opportunities in clinical practice. Experience has shown that students require support throughout the learning process. This is achieved through text-based study guides and a range of other support strategies. It is concluded that distance learning can be individualized to meet the professional and personal needs of students and provide quality, flexible learning opportunities for nurses and midwives, facilitating practice development and benefiting patient care.

Education, Distance↗
PubMed1985

Colour constancy with change of viewing distance under water.

Colour constancy is commonly considered to be the product both of high-order (cognitive) and of lower-order (retinal) mechanisms. A study is reported of colour appearance in situations where the spectral radiance of an object changes significantly with viewing distance. Subjects were instructed to match the colour appearance of a number of coloured tiles in air and at various viewing distances in different types of water. Colour-constancy ratios were calculated by comparing the visual data with simultaneously obtained spectroradiometric and photometric data. The obtained constancy ratios were attributed to the role of distance estimation in the determination of colour appearance, an effect that is presumably masked under normal viewing conditions, where long viewpaths are necessary to produce significant radiance changes. A similarity to the size-distance invariance hypothesis is noted.

Adult↗
PubMed1996

The depiction of distance: a Bartelian analysis.

Work by Bartel has shown that observers make systematic errors when attempting to set a receding row of staves at equal intervals, and make even-more-pronounced errors in the same direction when drawing a similar row; consequently, the factors that contribute to this systematic distortion in spatial representation were examined. The results indicate that the tendency to overestimate nearer distances and underestimate further distances in pictorial space may be enhanced both by increasing the size ratio of the nearest and furthest pictorial elements and by increasing the angle of convergence of represented parallel contours. However, it is clear that size ratio is the more powerful independent variable. The reasons for this discrepancy are discussed and an explanation of the pattern of pictorial distortion, in terms of a compromise between an objective representation of the relative estimated distance of the depicted distances and an inaccurately anticipated optical projection, is proffered.

Depth Perception↗
PubMed2003

Judging distance across texture discontinuities.

Sinai et al (1998 Nature 395 497-500) showed that less distance is perceived along a ground surface that spans two differently textured regions than along a surface that is uniformly textured. We examined the effect of texture continuity on judged distance using computer-generated displays of simulated surfaces in five experiments. Discontinuities were produced by using different textures, the same texture reversed in contrast, or the same texture shifted horizontally. The simulated surface was either a ground plane or a frontoparallel plane. For all textures and both orientations, less distance was judged in the discontinuous conditions than in continuous conditions. We propose that when a surface contains a texture discontinuity, a small area adjacent to the perceived boundary is excluded from judged distances.

Adult↗
PubMed2004

Perceiving distance: a role of effort and intent.

Perceiving egocentric distance is not only a function of the optical variables to which it relates, but also a function of people's current physiological potential to perform intended actions. In a set of experiments, we showed that, as the effort associated with walking increases, perceived distance increases if the perceiver intends to walk the extent, but not if the perceiver intends to throw. Conversely, as the effort associated with throwing increases, perceived distance increases if people intend to throw to the target, but not if they intend to walk. Perceiving distance combines the geometry of the world with our behavior goals and the potential of our body to achieve these goals.

Adult↗
PubMed2004

Distance estimation in a dynamic simulated environment: a visual field dependence problem?

Egocentric distance estimation implies that the subject perceives his own location in the environment. In a simulated environment, subjects have to transpose perceptively their own observation point in order to assume their virtual body position. As only visual information specifies this position, their ability to perceive the camera viewpoint should be linked to the field dependence independence factor (FDI). Field-independent subjects underestimated the mid-distance between their own virtual body position and a far-located target; their bisection was located between the projective (2-D) and the simulated (3-D) mid-distance which indicates their difficulty in considering the in-depth simulated spatial references. High correlations between the vertical estimation in the rod-and-frame test and the egocentric-distance-estimation task (with shifted camera) suggest a similar perceptive process in both tasks. This result is confirmed by the better performances of the field-dependent subjects in this condition. In conclusion, we discuss the relationship between FDI and the sense of presence in virtual environments.

Adult↗
PubMed2004

Judging egocentric distance on the ground: occlusion and surface integration.

On the basis of the finding that a common and homogeneous ground surface is vital for accurate egocentric distance judgments (Sinai et al, 1998 Nature 395 497-500), we propose a sequential-surface-integration-process (SSIP) hypothesis to elucidate how the visual system constructs a representation of the ground-surface in the intermediate distance range. According to the SSIP hypothesis, a near ground-surface representation is formed from near depth cues, and is utilized as an anchor to integrate the more distant surfaces by using texture-gradient information as the depth cue. The SSIP hypothesis provides an explanation for the finding that egocentric distance judgment is underestimated when a texture boundary exists on the ground surface that commonly supports the observer and target. We tested the prediction that the fidelity of the visually represented ground-surface reference frame depends on how the visual system selects the surface information for integration. Specifically, if information is selected along a direct route between the observer and target where the ground surface is disrupted by an occluding object, the ground surface will be inaccurately represented. In experiments 1-3 we used a perceptual task and two different visually directed tasks to show that this leads to egocentric distance underestimation. Judgment is accurate however, when the observer selects the continuous ground information bypassing the occluding object (indirect route), as found in experiments 4 and 5 with a visually directed task. Altogether, our findings provide support for the SSIP hypothesis and reveal, surprisingly, that the phenomenal visual space is not unique but depends on how optic information is selected.

Analysis of Variance↗
PubMed1995

Preferred viewing distances for handheld and structurally fixed displays.

This research was conducted to define viewing distance characteristics of individuals engaged in ordinary reading tasks. Specific attention was directed to assessing the potential relationship between observed distance and individual resting point accommodation. Consistent, statistically significant differences were observed across variable handheld and structurally-fixed hardcopy display configuration conditions. Relationships between observed viewing distance and resting point accommodation were not apparent. These findings suggest that simple eye-to-display viewing distance is fundamentally different for handheld text presentations and for the same text presented in a configuration similar to that of a video display terminal.

Accommodation, Ocular↗
PubMed1999

Distance learning for hospital managers.

Telemedicine technology enabled this class to meet. The Chapel Hill instructor could not have traveled to Scotland Neck for the classes, and the class members could not have taken time away from their jobs to travel to Chapel Hill. The technology allowed the participants to fit the classes into their schedules. For the group of managers at this small, isolated hospital, the experience of participating in a management class with an expert was a positive one. They were introduced to standard management practices, learned new skills, and formed a support group/team onsite. The students felt close to the leader, yet the physical distance made her an outsider in a way that encouraged frankness. The technology seemed to foster the best of both worlds--intimacy, yet physical distance and, thus, safety. These new managers were able to take part in a course that taught tangible skills for improving their job performance and, more important, afforded access to resources outside of Halifax County. They were able to step away from their daily routine and interact with outsiders and each other in new ways, without the stress and expense of travel. The results of this pilot study indicate that distance learning is feasible for courses of this kind. Staff burnout and turnover are chronic problems in rural facilities, with isolation contributing to job dissatisfaction. Distance learning offers exciting possibilities for addressing these problems in healthcare settings across the country.

Attitude of Health Personnel↗
PubMed2003

Distractor interference in selective reaching: dissociating distance and grouping effects.

In the present experiment, the authors sought to differentiate between a distance and a grouping explanation for the symmetric versus asymmetric patterns of distractor interference in selective reaching. Participants (N = 16) pointed to a green target that appeared either with or without a red distractor. Target-distractor separation was manipulated within an array of 5 closely grouped stimulus boxes, and distractor interference (difference in performance between trials with and trials without a distractor) was measured in reaction time, movement time, percentage errors, and movement endpoints. Small distances (5 mm) between target and distractor yielded a symmetric pattern of interference, whereas large distances (20 mm) yielded an asymmetric pattern, with more interference from near than from far distractors. Those findings support the distance account of distractor interference and refute the grouping account.

Adult↗
PubMed2005

What makes a route appear longer? An experimental perspective on features, route segmentation, and distance knowledge.

Five experiments performed in a desktop virtual-reality setting investigated the influence of environmental features--that is, noticeable landmarks along the route--on distance estimation. Landmarks were of two types: Either they simply "filled" the route or they "filled" and also segmented it, thereby inducing a hierarchical structuring of the route. Previous research had left the question open of whether a filling or a segmenting feature leads to an overestimation of a distance along the route. Our experiments showed different results dependent on the kind of space: If an environment was learned from a route perspective, filling and segmenting environmental features led to overestimations of distances, while the segmenting of a route induced by a grouping of similar features did not. If the environment was learned from a map that afforded a survey perspective, route structuring induced through a segmenting feature or by phenomenal grouping led to an overestimation of distances, whereas features that merely filled the route did not.

Adult↗
PubMed1990

Buffon's needle and the estimation of migration distances.

"A procedure is suggested for estimating migration distances from data on the proportion of migrants crossing regional boundaries. The method makes use of Buffon's needle, a problem in geometrical probability from the eighteenth century.... The procedure is described for various scenarios that differ in their assumptions about region shape, the spatial distribution of population, and the distribution of migration distances. An application to migration distances in the United States is given, and additional attention is given to the estimation of intraregional migration distances." (SUMMARY IN FRE)

Americas↗
PubMed2004

True three-dimensional displays that allow viewers to dynamically shift accommodation, bringing objects displayed at different viewing distances into and out of focus.

Under natural viewing conditions, viewers do not just passively perceive. Instead, they dynamically scan the visual scene by shifting their eye fixation and focus between objects at different viewing distances. In doing so, the oculomotor processes of accommodation (eye focus) and vergence (angle between lines of sight of two eyes) must be shifted synchronously to place new objects in sharp focus in the center of each retina. Accordingly, nature has reflexively linked accommodation and vergence, such that a change in one process automatically drives a matching change in the other. Conventional stereoscopic displays force viewers to try to decouple these processes, because while they must dynamically vary vergence angle to view objects at different stereoscopic distances, they must keep accommodation at a fixed distance--or else the entire display will slip out of focus. This decoupling generates eye fatigue and compromises image quality when viewing such displays. In an effort to solve this accommodation/vergence mismatch problem, we have built various prototype displays that can vary the focus of objects at different distances in a displayed scene to match vergence and stereoscopic retinal disparity demands and better simulate natural viewing conditions. By adjusting the focus of individual objects in a scene to match their stereoscopic retinal disparity, the cues to ocular accommodation and vergence are brought into agreement. As in natural vision, the viewer brings different objects into focus by shifting accommodation. As the mismatch between accommodation and vergence is decreased, natural viewing conditions are better simulated and eye fatigue should decrease.

Accommodation, Ocular↗
PubMed2003

The right supratemporal plane hears the distance of objects: neuromagnetic correlates of virtual reality.

The neural mechanisms of auditory distance perception, a function of great biological importance, are poorly understood. Where not overruled by conflicting factors such as echoes or visual input, sound intensity is perceived as conveying distance information. We recorded neuromagnetic responses to amplitude variations over both supratemporal planes, with and without auditory spatial simulations. In the absence of other cues for distance, including those provided by auditory virtual reality, amplitude changes elicited enhanced preattentive responses over the right temporal lobe, indicating hemispheric lateralization of the 'where' pathway in the human. Lesion studies in monkeys and humans have shown that the rostral part of the right superior temporal cortex contributes to spatial awareness in the visual domain. Our data indicate that the distance to a sound source is processed within the adjacent right auditory cortex, thus extending the recent model of a right-hemisphere temporal multisensory matrix that subserves the integration of space-related data across visual and auditory modalities.

Adult↗
PubMed2001

Lessons learned from a distance-based consulting program to assist faculty development projects.

Changes in faculty roles and demographics necessitate a re-examination of the types of professional development opportunities offered in academic institutions. A distance-based consulting program was designed to assist faculty development projects as they progress through all stages of faculty development: needs assessment, project design, implementation, and, in particular, program evaluation and dissemination of results (i.e., presentations and published articles). The progress of 17 faculty development projects in primary care educational sites that received assistance in the United States and Canada was tracked over two years. Three factors were identified as having the most impact on the success of faculty development projects: (1) funds committed to and designated for faculty development; (2) funded, protected time for at least one person to implement the faculty development initiative; and (3) an environment capable of supporting faculty development initiatives (e.g., no major budget shortfall, few faculty transitions, a strong mission, no threat of mergers). Only a few of the participating sites reached the stage of evaluating and publishing articles about the outcomes of their projects within the designated 15-month time frame, with many sites reporting environmental impediments to project success. The authors describe the institutional characteristics that facilitated project success, assess the usefulness of distance-based consulting efforts, and offer recommendations for future distance-based consulting programs. They conclude by noting that the personal touch (i.e., one-on-one contact with consultants) is what is most appreciated, and that excellent one-on-one, in-person assistance may be inherently more effective than even the best-run distance-based consulting.

Canada↗
PubMed2000

Measurement of daily walking distance-questionnaire versus pedometer.

PURPOSE: This study compared measurements of daily walking distance on the College Alumnus questionnaire (CAQ) and a pedometer. METHODS: A total of 96 men and women (25-70 yr of age) with a wide range of physical activity habits were studied. Physical activity index was computed from the College Alumnus questionnaire (PAI-CAQ) as the sum of the energy expended in stair climbing, walking, and sports and recreational physical activity. Data on walking distance were compared with values obtained from the Yamax electronic pedometer (DW-500B). Participants wore the pedometer for 7 consecutive days, except when sleeping, showering, or performing sports and recreational activities. RESULTS: Subjects underestimated their daily walking distance on the CAQ, compared with the pedometer (1.43 +/- 1.01 vs 4.17 +/- 1.61 km x d(-1)). The energy expended in walking was correspondingly lower on the CAQ, compared with the pedometer-derived values (555 +/- 405 versus 1608 +/- 640 kcal x wk(-1)). CONCLUSIONS: These findings suggest that electronic pedometers are useful for examining questions about walking distance on physical activity questionnaires.

Adult↗
PubMedDate not supplied

Discovering co-learning with students in distance education sites.

Distance education is promoted as an effective way to reach more students, but how effective are interactive learning strategies in distance nursing courses? The authors discuss how nursing students adjusted to distance technologies and became actively involved in creating an environment that enabled development of supportive co-learning relationships. Learner perspectives on teaching strategies, distance learning, and becoming nurses are described.

Adaptation, Psychological↗
PubMed1980

Accommodation, convergence, and distance perception in low illumination.

The role of oculomotor adjustments for distance perception in dim light was investigated while preserving the natural interactions between accommodation and convergence. The results show that perceived distance in the dark is biased toward an intermediate value that is correlated with the vergence adjustment assumed in darkness but unrelated to the dark focus of accommodation. A subsequent experimient showed that short-term adaptation to base-out prisms and negative lenses of corresponding strength affects perceived distance and dark convergence but has no influence on the dark focus of accommodation. These findings were interpreted as indicating that convergence is a more important distance cue than accommodation under low illumination and that the physiological resting states of convergence and accommodation are relatively independent.

Accommodation, Ocular↗