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At least 1,747 records · Page 97Linked to original sources
PubMed1992

Influence of windshield tint and tilt on recognition distance under mesopic conditions.

The influence of the angle of inclination and tint of windshields on recognition distance was tested in 94 subjects aged 20-83 years. Both clear and tinted (heat-absorbing) windshields were tested. Light transmission (in the vertical position) was 90.3% for the clear windshield and 81.0% for the tinted windshield. The windshields could be set at angles of 0 degree (vertical), 30 degrees, 50 degrees and 70 degrees of inclination. The tests were performed at night with low-beam headlights (mesopic conditions). A Landolt ring (diameter 43.5 cm; contrast 1:1.5) served as a test stimulus; it was painted on a disc 87 cm in diameter that could be rotated in steps of 45 degrees. The mean recognition distance without the windshield was 32.2 m +/- 5.5 m (mean +/- SD). It decreased to 31.0 m +/- 5.6 m (29.0 m +/- 5.3 m) by using a clear windshield in the vertical position (values for the tinted windshield are shown in parentheses): 30.1 m +/- 5.6 m (27.9 m +/- 5.3 m) with a 50 degrees angle of tilt, and 28.5 m +/- 5.4 m (26.9 m +/- 5.1 m) with a 70 degrees angle. The differences between the recognition distances obtained using the various tilts and tints were small but statistically significant (P < 0.01 in all cases: Student's paired t-test). Since the performance of the human eye is stressed to its limits during nighttime driving, our study suggests that extreme tilt of the windshield should be avoided and that the option of delivering cars equipped with a heat-absorbing but clear front windshield should be provided.

Accidents, Traffic↗
PubMed2004

Developing an interaction-centered evaluation tool for distance education.

Web-based distance instruction is growing in popularity. As more courses and programs go online, instructional methods and technologies are changing to meet new demands. These courses and instructional methods need be evaluated to determine their quality and to aid in their development. An instrument that measures the quality of student interaction within courses could play a useful role in this evaluation. The objective of this project was to produce an interaction-centered evaluation tool for distance education. We developed items for the evaluation tool based on a review of the literature and interviews with distance education faculty. We then conducted a measurement study to determine the instrument's validity and reliability. Fifty-five students in seven medical informatics courses participated in this study. Questionnaire items were included or rejected based on their fit with underlying theoretical constructs. In conclusion, the Web-based evaluation tool developed in this project measures student perception of quality of course interactions with demonstrated validity and reliability.

Computer-Assisted Instruction↗
PubMedDate not supplied

R.T.s' interest in advanced-level certification and distance learning.

OBJECTIVE: To determine the interest of radiologic technologists in obtaining advanced-level certification and their acceptance of distance learning as an educational method to pursue advanced-level certification. METHODS: Researchers surveyed a random sample of 1300 registered technologists (R.Ts) certified in radiography. Data were analyzed using basic univariate statistics and logistic regression calculations. RESULTS: The majority of respondents (72%) expressed an interest in obtaining an advanced-level certification. Furthermore, 93% of those respondents indicated that distance learning was an acceptable method for obtaining the necessary course work. Interest in certification for computed tomography (CT) or magnetic resonance (MR) imaging was selected by nearly 25% of the respondents. Most plan to begin course work within the next 1 to 2 years, are willing to dedicate 4 to 6 hours per week and up to dollar 250 per year to obtain their goals. Although most employers (63%) do not contribute any financial assistance, most R.Ts (53%) indicated that employer support did not influence their decision to pursue a certification. CONCLUSION: This study supports the need for quality distance learning programs, particularly in the areas of CT and MR.

Adult↗
PubMedDate not supplied

Distance learning: investing in employees' futures.

The compassion and overall efficiency of those technologists with whom the patient interacts impacts the patient's decision to utilize the facility in the future. Because employee interaction largely influences patient satisfaction, the radiology administrator is challenged to recruit, but more importantly, retain quality employees. Benefit options designed to provide employees the latitude to achieve personal goals as well as professional obligations can be valuable recruitment and retention tools. Ultimately, the purpose of an employee benefit is to promote employee satisfaction, leading to employee retention and culminating in greater patient satisfaction. Since the "ability to influence their career" is reported to be a major area of difference in perceived agreement between the technologist and administrator, it is important to consider avenues for attaining education and skills to meet employee goals far advance. ment within the organization. Distance education, described as a method to provide educational offerings without displacing the learner from the workfarce and his or her community setting, has been successfully implemented in many allied health specialties. Distance learning farmat options include, but not limited to, written correspondence courses, audiotapes, video, Internet, and satellite. These options provide educational access to those with employment and family constraints. The funds that would be spent on recruitment or temporary help can be applied toward training or retraining current employees. Typically, one year of service is required for each year of schooling funded. In some cases, if the training is offered via distance learning, the clinical training portion of the educational program can be conducted at the facility sponsoring the student. Providing clinical training at a facility reduces the student's learning curve associated with transitioning into the open position.

Education, Distance↗
PubMed2005

General practice supervision at a distance--is it remotely possible?

BACKGROUND: The Remote Vocational Training Scheme (RVTS) trains GPs while in solo rural or remote practice. General practice registrars choose an experienced rural or remote practitioner as their distant supervisor. METHOD: During a teacher training telephone tutorial series RVTS general practice supervisors discussed the unique features of this model of general practice training, and shared their perspectives on how to make this distance supervision effective. RESULTS: This paper outlines the unique qualities of general practice registrars, the registrar-supervisor relationship and the content of tutorials, in the context of remote supervision. This paper suggests ways to provide educational support despite geographical distance. DISCUSSION: Experienced rural and remote GPs can provide effective supervision at a distance. The RVTS provides an innovative, alternative model for training GPs for rural and remote practice. Further qualitative research on this topic is required.

Australia↗
PubMed1985

Scales for perceived egocentric distance in a large open field: comparison of three psychophysical methods.

Scales for perceived egocentric distance produced by three psychophysical methods in four ranges of distances were compared. It was found that (a) the exponents produced by ratio and fractionation methods are in good agreement; (b) the exponents of both these methods were larger than those produced by magnitude estimation; (c) an increase in range of distance was associated with a decrease in exponent, but this diminution seems to interact with the method used; (d) for all the psychophysical methods used, there was large variability in the individual exponent; (e) the exponent was smaller than 1.0 for approximately 78% of the pooled sample, with all adult observers (N = 612) considered; and (f) an arithmetic mean exponent equal to 0.90 represents fairly all the results obtained.

Adult↗
PubMed1995

The right questions to assess materials. Selecting distance learning material.

1. Distance learning provides real educational opportunities, equal to and complementary with, traditional taught programme approaches. 2. Important questions to ask about distance learning include relevance to practice, accessibility, quality assurance, assessment and value for money. 3. Distance learning need not be lonely and isolating, and can provide education that travels with students--important in today's professional context.

Distance Perception↗
PubMed1993

Mental comparison: P300 component of the ERP reflects the symbolic distance effect.

The symbolic distance effect was studied in a numerical comparison task by means of behavioural measures and event-related potentials (ERP). Two numbers in the range from 11 to 20 were presented simultaneously and the subjects had to indicate if the right side number was smaller or larger than the left side number. Reaction time, error rate and ERPs were selectively averaged according to the numerical differences between the two numbers. The symbolic distance effect was confirmed: Reaction times and error rates decreased significantly with increasing difference between the two numbers. A significant distance effect was also found for both P300 amplitude and latency. The larger the numerical difference the larger the P300 amplitude and the P300 latency tended to be shorter. This finding suggests that the numerical difference is effective already during stimulus encoding.

Adult↗
PubMed1997

Marriage: distance between birthplaces and age difference between mates.

The methodology of potential mate analysis can be used to obtain information about the determinants of marriage. This study investigates the influence of the distance between birthplaces and of age difference between mates. We use a new method of potential mate analysis that involves a sample of potential mates simulated from a sequence of actual mates. The differences between actual and potential mates are investigated using a logistic model and by direct comparison of distributions. The logistic model gives a poor fit. The comparison of distributions reveals no significant difference in distance between birthplaces for actual and potential mates or, at any rate, no difference large enough to be demonstrated by our small sample. A marked difference is observed for marriages in which the male is slightly older. The distance between birthplaces in our sample is shorter than in Great Britain.

Adult↗
PubMed1976

The adjustment of reaching behavior to object distance in early infancy.

The prehensile activity and looking behavior of 2- and 5-month-old infants were videotaped in the presence of objects placed within and beyond possible contact distance. There was only a consistent adjustment of reaching behavior to stimulus distance in the case of the 5-month-old group. The distance discrimination evident in the prehensile activity of the older infants was paralleled by a reduction in the amount of attention paid to far objects.

Attention↗
PubMed1998

The distance angle to target in surgery for intermittent exotropia.

BACKGROUND: Patients with intermittent exotropia may have an increase in their angle of strabismus in the distance when the angle is measured either after 1 hour of monocular occlusion or while the patients fixate on a distant target outdoors. The hypothesis that surgery should be performed for this larger deviation has been suggested but not tested. OBJECTIVES: To test the hypothesis that surgery should be performed for the increased angle of strabismus in the distance in patients with intermittent exotropia and to investigate the factors that influence the angle of misalignment. METHODS: A prospective, clinical trial was conducted of patients with intermittent exotropia in whom the angle of misalignment in the distance increased after 1 hour of monocular occlusion or while the patients fixated on an outdoor target. The study group underwent surgery for the largest deviation measured; the control group underwent surgery for the initial angle measured at 6 m. All patients in whom the angle of misalignment increased while the patients were looking at an outdoor target were additionally measured in indoor illumination at 24 m and also at 6 m under floodlights that simulated outdoor illumination. Ninety patients undergoing surgery were randomized. RESULTS: Forty-three (86.0%) of the 50 patients undergoing surgery for the largest angle measured had a satisfactory outcome vs 25 (62.5%) of the 40 patients in the control group (P<.001). The mechanism for the increase in exotropia while fixating on an outdoor target was studied in 76 patients, and the results were variable. CONCLUSIONS: The angle of strabismus in patients with intermittent exotropia undergoing surgery should be measured while the patients fixate on an outdoor target and after 1 hour of monocular occlusion. Surgery should be performed for the largest angle measured.

Accommodation, Ocular↗
PubMed2003

Using test dummy experiments to investigate pediatric injury risk in simulated short-distance falls.

BACKGROUND: Short-distance falls, such as from a bed, are often falsely reported scenarios in child abuse. In attempting to differentiate between abusive and nonabusive injury, knowledge of factors that affect injury risk in falls could prove useful. OBJECTIVES: To assess the biomechanics associated with simulated short-distance falls in children (one fall scenario, without attempting to maximize injury potential) and to investigate the effect of impact surface type on injury risk. METHODS: Repeatable fall experiments from bed height (0.68 m) onto different surfaces were conducted using an instrumented side-lying Hybrid II 3-year-old test dummy. Biomechanical measures assessed in falls included head acceleration, pelvis acceleration, femur loading, and head injury criteria. RESULTS: Fall dynamics resulted in the pelvis or legs making first contact. Biomechanical measures assessed in simulated bed falls were below known head injury criteria and lower extremity injury thresholds. The impact surface type had a significant effect on head injury risk and lower extremity loading. Playground foam proved to have the lowest associated injury risk of all the tested surfaces. CONCLUSIONS: The biomechanics of a child falling from a short distance, such as from a bed, were investigated using an experimental laboratory mock-up and an instrumented test dummy. Despite the impact surface having an effect on injury risk, rolling from a 0.68-m (27-in) horizontal surface from a side-lying posture presented low risk of contact-type head injury and leg injury on all tested impact surfaces.

Accidental Falls↗
PubMed1998

Early synaptogenesis in vitro: role of axon target distance.

In contrast to some previous reports suggesting a delay in synapse formation in vitro, we found that under ideal conditions, most hippocampal and hypothalamic rat neurons were synaptically coupled after 3 or 4 days in vitro. Synaptophysin immunocytochemistry revealed strongly stained presynaptic boutons by 3 days in vitro. Studies with time-lapse laser confocal imaging of FM1-43 revealed that axonal boutons were recycling their synaptic vesicles, an indication of synapse formation, as early as 3 days after plating. To test the hypothesis that neurite outgrowth was enhanced in high-density cultures, thereby increasing the probability of synapse formation, neurons were transfected with the jellyfish green fluorescent protein (GFP) gene. After 2 days in high-density cultures, green fluorescent neurites were about three times longer than in sister neurons plated in low-density cultures. Even in single dishes, GFP-transfected cells in contact with other neurons had neurites that were at least three times longer and grew faster than more isolated cells. Neurons grew longer neurites (+51%) when growing on surface membranes of heat-killed neurons than on polylysine, underlining the importance of plasma membrane contact. Calcium imaging with fura-2 and whole cell recording showed that both GABA and glutamate presynaptic release occurred after 3 or 4 days in vitro in high-density cultures but was absent in low-density cultures at this time. Together, these morphological, cytochemical, and physiological data suggest that the distance an axon must grow to find a postsynaptic partner plays a substantial role in the timing of synapse formation. Although other factors in vitro may also play a role, the distance to a postsynaptic target, which defines the interval during which an axon grows to its target, can probably account for much of the difference in timing of synapse formation previously reported in vitro. A short intercell distance may increase the concentration of limited amounts of trophic factors available to a nearby cell, and once contact is made, a neuronal membrane provides a superior substrate for neuritic elongation.

2-Amino-5-phosphonovalerate↗
PubMed2000

Facilitated tip-positioning and applications of non-electrode tips in scanning electrochemical microscopy using a shear force based constant-distance mode.

In scanning electrochemical microscopy (SECM) a microelectrode is usually scanned over a sample without following topographic changes (constant-height mode). Therefore, deconvolution of effects from distance variations arising from non-flat sample surface and electrochemical surface properties is in general not possible. Using a shear force-based constant distance mode, information about the morphology of a sample and its localized electrochemical activity can be obtained simultaneously. The setup of the SECM with integrated constant-distance mode and its application to non-flat or tilted surfaces, as well as samples with three-dimensional surface structures are presented and discussed. The facilitated use of non-amperometric tips in SECM like enzyme-filled glass capillaries is demonstrated.

Electrochemistry↗
PubMed2001

Influence of solvent and configuration of residues at positions 2 and 3 on distance and mobility of pharmacophore groups at positions 1 and 4 in cyclic enkephalin analogues.

The analgesic activity of opioid peptides is mainly connected with their affinity and selectivity for the mu-receptors. The biological activity of cyclic opioid analogues depends on mutual orientation and conformational freedom of aromatic pharmacophore groups at positions 1 and 4. The distance and distance distributions between chromophores at positions 1 [Phe(p-NO(2)), p-nitrophenylalanine] and 4 [Nal, beta-(2-naphthyl)alanine], which constitute an energy donor-acceptor pair, were calculated based on measured fluorescence intensity decays of a donor (Nal). The influence of the solvent and configuration of the residues at position 2 and 3 on donor-acceptor distance distribution and mobility of pharmacophore groups at position 1 and 4 in cyclic enkephalin analogues are discussed.

Enkephalins↗
PubMed2000

Resistance to sliding of orthodontic appliances in the dry and wet states: influence of archwire alloy, interbracket distance, and bracket engagement.

Having established dimensional and mechanical characteristics, the resistances to sliding (RS) were measured in vitro for various archwires against stainless steel brackets. Using stainless steel ligatures, a constant normal force (300g) was maintained while second-order angulation (straight theta) was varied from -12 degrees to +12 degrees. Using miniature bearings to simulate contiguous teeth, five experiments each were run in the dry or wet states with human saliva at 34 degrees C as a function of four archwire alloys, five interbracket distances, and two bracket engagements. Outcomes were objectively analyzed to establish when theta=0, and the relative contact angles ( theta(r)) were replotted. Critical contact angles (theta(c)) that were determined via experimentation were in good agreement with theory. Slopes and y-intercepts were tabulated from linear regression equations of RS against theta plots in both the passive (theta < or = theta (c)) and active ( theta > or = theta(c)) configurations, for which theta = theta(c) identified the boundary between classical friction and binding phenomena. Stiffer archwires and shorter interbracket distances exacerbated binding, whereas, once corrected for differing bracket engagement, RS was independent of slot dimension. Unlike earlier results in the passive configuration, in the active configuration couples comprised of titanium alloys (NiTi and (beta-Ti) had higher RS values in the wet versus the dry state. For those archwire alloys evaluated, two empirical expressions were adduced that comprise the binding component, the yield strength or elastic limit, and the beam length, which implicitly represent the stiffness, flexibility, and interbracket distance.

Dental Alloys↗
PubMed1983

Failure of linguistic relationships to predict genetic distances between the Waiãpi and other tribes of lower Amazonia.

Data on blood group, serum protein, erythrocyte enzyme, and histocompatibility antigen (HLA) traits are presented for the Waiãpi, a Tupi-speaking tribe of the Brazilian and French Guianas. Intra- and intertribal comparisons have been made between these data, and previously published data from French Guiana, from another Tupi tribe and from other tribes of neighboring areas, and from the continent as a whole. For this purpose, we have modified the usual measure of genetic distance to obtain a value which is independent of the number of loci being considered. The intertribal genetic distances do not correlate with linguistic affinity. Social differences, which may have affected the rate of drift from the continental mean, correlate better with genetic distances.

Blood Group Antigens↗
PubMed1984

Relationship between heterozygosity and genetic distance in the three major races of man.

In pairwise comparisons of gene frequency data from the three major races of man, the single locus measures of the heterozygosity within and the genetic distance between races are shown to be strongly correlated across the loci coding for red cell proteins and enzymes. The intercept of the regression line of genetic distance on heterozygosity in protein enzyme loci is statistically insignificant. These findings suggest that the genetic variability at the enzyme and protein loci in man is probably maintained by a balance of mutation and random genetic drift. At the blood group loci, however, the observed relationship between genetic distance and heterozygosity does not follow the expectation of the neutral mutation hypothesis. These observations are discussed in terms of the changes in probability of identical monomorphism in two populations during the process of gene differentiation.

Blood Group Antigens↗