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PubMed2004

Semantic distance norms computed from an electronic dictionary (WordNet).

WordNet, an electronic dictionary (or lexical database), is a valuable resource for computational and cognitive scientists. Recent work on the computing of semantic distances among nodes (synsets) in WordNet has made it possible to build a large database of semantic distances for use in selecting word pairs for psychological research. The database now contains nearly 50,000 pairs of words that have values for semantic distance, associative strength, and similarity based on co-occurrence. Semantic distance was found to correlate weakly with these other measures but to correlate more strongly with another measure of semantic relatedness, featural similarity. Hierarchical clustering analysis suggested that the knowledge structure underlying semantic distance is similar in gross form to that underlying featural similarity. In experiments in which semantic similarity ratings were used, human participants were able to discriminate semantic distance. Thus, semantic distance as derived from WordNet appears distinct from other measures of word pair relatedness and is psychologically functional. This database may be downloaded from www.psychonomic.org/archive/.

Cognitive Science↗
PubMed2000

Temporal and spatial distance in situation models.

In two experiments, we investigated how readers use information about temporal and spatial distance to focus attention on the more important parts of the situation model that they create during narrative comprehension. Effects of spatial distance were measured by testing the accessibility in memory of objects and rooms located at differing distances from the protagonist's current location. Before the test probe, an intervening episode was inserted in the narrative. Story time distance was manipulated by stating that the intervening episode lasted for either minutes or hours. Discourse time--that is, time spent reading from prime to test--was manipulated by describing the intervening episode either briefly or at length. Clear effects of story time distance and spatial distance on accessibility were found, whereas discourse time distance did not affect accessibility. The results are interpreted as supporting constructionist theories of text comprehension.

Adult↗
PubMed2000

A new cut-off point of thyromental distance for prediction of difficult airway.

BACKGROUND: Difficult intubation, often unexpected, remains a primary concern for the anesthesiologist. None of the bedside tests have proven to be efficacious and highly predictive. The prupose of this study was to correlate the full range of thyromental distance with both the Cormack grade and the Mallampati score. METHODS: One hundred and sixty patients undergoing general anesthesia were included in the study. Patients with abnormal atlanto-occipital extension, small chin size and mouth opening were excluded from the study. The thyromental distance, the Mallampati score, and the Cormack grade were determined in all patients. The correlation between the thyromental distance and each of the Cormack grade and the Mallampati score was determined, as well as the correlation between the Mallampati score and the Cormack grade. The cut-off value of the tyromental distance that discriminated best between patients with easy glottic visualization (Cormack grade 1,2) vs. difficult visualization (Cormack grade 3,4) was derived. RESULTS: A significant and high correlation was observed between the thyromental distance and the Cormack grade (r = -0.72). In contrast, a lower correlation was observed between the thyromental distance and the Mallampati score (r = -0.41) and the Mallampati score and the Cormack grade (r = 0.47). A cut-off value for the TMD of 4 cm was the best in discriminating between patients with difficult and easy glottic visualization. The combination of TMD < or = 4 cm and Mallampati score of 3,4 predicted the patients with the most difficult glottic visualization. CONCLUSION: Patients with a thyromental distance greater than 4 cm can be easily intubated. In contrast, when the TMD < or = 4 cm, tracheal intubation is difficult in 48% of patients if the Mallampati score is 1,2 and in 79% if the Mallampati score is 3 or 4.

Adolescent↗
PubMed2002

Inner canthal distance and geometric progression as a predictor of maxillary central incisor width.

STATEMENT OF PROBLEM: Estimating the mesiodistal width of maxillary central incisors may be difficult when artificial teeth are selected for edentulous subjects. PURPOSE This study examined the relationship between inner canthal distance and maxillary central incisor mesiodistal width in terms of the geometric progression popularly known as the golden proportion. MATERIAL AND METHOD: Two hundred twenty-nine dentate Saudi subjects (120 males, 109 females; mean age 21.46 years) free from facial and dental deformities were examined. The mesiodistal width of each maxillary central incisor was measured between its interproximal contact points. The inner canthal distance was measured from medial angle to medial angle of the palpebral fissures of the eyes. The common ratios of geometric progression are 0.618 and 1.618. The inner canthal distance of each subject was multiplied by a decreasing function value of the geometric progression term (0.618) to provide the combined width of 2 central incisors. The product was then divided by 2 to obtain the width of a single maxillary central incisor. A t test was used to identify any significant differences in mesiodistal tooth width and inner canthal distance by gender. Agreement between the measured and calculated central incisor widths was evaluated with Pearson's correlation coefficients, as was intraexaminer reliability. Significance was set at alpha=.05. RESULTS: The mean inner canthal distance of male and female subjects was 28.7 +/- 1.7 mm and 27.9 +/- 2.1 mm, respectively. The mean maxillary central incisor width of male and female subjects was 8.87 +/- 0.5 mm and 8.68 mm +/- 0.4 mm, respectively. Differences between the mean values for both measurements were significant (P =.002). The actual and calculated widths of the natural maxillary central incisors were found to be highly correlated (r =.943). CONCLUSION: Within the population tested, a significantly higher mean inner canthal distance and maxillary central incisor width were recorded for male subjects. Inner canthal distance, when multiplied by a decreasing function value of the geometric progression term and then divided by 2, was a reliable predictor of maxillary central incisor width.

Adult↗
PubMedDate not supplied

A systematic review of the quality of research on hands-on and distance healing: clinical and laboratory studies.

PURPOSE: To systematically review the quality of published experimental clinical and laboratory research involving hands-on healing and distance healing between 1955 and 2001. DATA SOURCES: Studies were identified through comprehensive literature searches on spiritual healing in MEDLINE, PSYCH LIT, EMBASE, CISCOM, and the Cochrane Library from their inceptions to December 2001. STUDY SELECTION: We selected published randomized, controlled trials of spiritual healing (hands-on healing and distance healing) done in clinical and laboratory settings, all of which had been peer reviewed. DATA EXTRACTION: Independent quality assessment of internal validity was conducted on all identified studies using the comprehensive Likelihood of Validity Evaluation scale. Clinical and laboratory studies were analyzed separately and then subdivided into hands-on healing or distance healing interventions. RESULTS: A total of 45 laboratory and 45 clinical studies published between 1956 and 2001 met the inclusion criteria. Of the clinical studies, 31 (70.5%) reported positive outcomes as did 28 (62%) of the laboratory studies; 4 (9%) of the clinical studies reported negative outcomes as did 15 (33%) of the laboratory studies. The mean percent overall internal validity for clinical studies was 69% (65% for hands-on healing and 75% for distance healing) and for laboratory studies 82% (82% for hands-on healing and 81% for distance healing). Major methodological problems of these studies included adequacy of blinding, dropped data in laboratory studies, reliability of outcome measures, rare use of power estimations and confidence intervals, and lack of independent replication. CONCLUSIONS: When laboratory studies were compared to clinical studies in the areas of hands-on healing and distance healing across the quality criteria for internal validity, distance healing studies scored better than hands-on healing studies, and laboratory studies fared better than clinical studies. Many studies of healing contained major problems that must be addressed in any future research.

Clinical Trials as Topic↗
PubMed1978

Effect of the distance of optokinetic stimuli from the eyes on certain parameters of the optokinetic nystagmus.

The above effect was studied in 65 subjects with normal vision (mean age 20 years) in investigations in which the following factors were successively changed: distance of optokinetic stimuli from the eyes; this distance and angular velocity of stimuli; distance and frequency of stimuli or finally distance and accommodation level. The angular velocity of the pursuit nystagmus phase was found to be by far the highest and simultaneously the closest to the angular velocity of optokinetic stimuli when the latter are 1.5m from the eyes. With shorter distances, the velocity of the pursuit movements lags steadily behind that of stimulus velocity. This change is conditioned by changes in OKN amplitude since its frequency as a whole does not change. Even though the accommodation level significantly affects the velocity of the pursuit nystagmus phase, the dependence on the distance of optokinetic stimuli from the eyes persists even after atropinization. The interpretation of these findings must take into account sepcifically the demands on accommodation, convergence, and on visual attention which are increased with shorter distances.

Accommodation, Ocular↗
PubMed2005

Using anovaginal distance at the beginning of labor to predict the likelihood of instrumental delivery.

OBJECTIVE: To investigate whether anovaginal distance in parturients has an impact on the instrumental delivery rate. STUDY DESIGN: In this study with prospective data collection and a convenience sample, 400 parturients planning for vaginal delivery at term with a singleton fetus in vertex presentation were enrolled. Anovaginal distance was measured in the lithotomy position during the latent phase of labor or early first stage. This distance is thought to reflect the angle of inclination of the birth canal axis. RESULTS: At the cutoff point of 25 mm for anovaginal distance, the odds ratio for instrumental delivery was 2.5 (95% CI 1.48-6.6, p<0.05). A final model of instrumental delivery, controlling for various confounding variables, correctly predicted 91.38% of the instrumental deliveries (p<0.0001). The variables anovaginal distance >25 mm (OR 2.9, 95% CI 1.2-6.7, p=0.01), parity (OR 0.54, 95% CI 0.29-0.99, p=0.046) and duration of second stage of labor (OR 1.01, 95% CI 1.004-1.01, p=0.001) significantly contributed to the prediction of instrumental delivery after controlling for the other parameters. CONCLUSION: Women with an anovaginal distance of >25 mm at the beginning of labor was 2.5 more likely to undergo instrumental delivery than were women with an anovaginal distance of <25 mm.

Adult↗
PubMed2005

Effect of starting distance on vertical ground reaction forces in the normal dog.

The purpose of this study was to evaluate the effect of starting distance on the peak vertical force (PVF) and associated vertical impulses (VI) of normal dogs. Five dogs of similar weight and body type were trotted at a velocity of 1.6-2.2 m/s from each of three starting distances; 2, 4, and 6 m, from the first plate in a two plate test field. A total of ten trials were recorded from each starting distance, five left first contacts and five right first contacts. Each ground reaction force (GRF) of interest was evaluated both within and between the three starting distances using a complete block ANOVA. There was not any significant effect of distance found on peak vertical forces in our study. However, distance did affect VI. Forelimb VI generated at a 2 m trot was significantly less than VI generated at a 6 m trot. Neither extreme distance was found to be significantly different than the 4 m VI. The VI of the hind limb was not significantly affected.

Animals↗
PubMed1987

Responses of distance runners and sprinters to exercise in a hot environment.

The responses of highly trained distance runners and track sprinters and age-matched untrained men were compared during bicycle ergometry in a 40 degree temperature-controlled environmental chamber. There were no differences among groups in rectal temperature following the 90 min exercise bout. Distance runners had a lower heart rate than either sprinters or untrained subjects. There was no difference in heart rate between sprinters and untrained subjects. Distance runners and sprinters had a much greater sweat rate than untrained subjects and dissipated a greater proportion of their total heat load by evaporation of sweat. Sprinters, however, had a lower sweat rate than distance runners in the hot environment and could only maintain as low a skin temperature as distance runners for 75 min of the 90 min session. Both aerobic training and anaerobic training confer some degree of protection from heat injury during exercise in a hot environment. However, sprinters have a higher heart rate and cannot sustain a low skin temperature as long as distance runners. Sprinters lost their advantage over untrained subjects in skin temperature after 75 min of exercise in a hot environment and did not have a lower heart rate than untrained subjects. Distance runners had a significantly lower heart rate and maintained a lower skin temperature than untrained subjects for the entire 90 min exercise bout.

Acclimatization↗
PubMed1986

Distance measurements between metal-binding sites of calmodulin and from these sites to Cys-133 of troponin I in the binary complex.

Distances between the four Ca2+-binding sites of calmodulin (CaM) have been measured by fluorescence energy transfer techniques using Eu3+ and Tb3+ as energy donors and a number of other lanthanide ions (Ln3+) as acceptors. It was shown previously that lanthanide ions preferentially bind to sites I and II of CaM with an affinity higher than that for sites III and IV (Kilhoffer, M.-C., Demaille, J. G., and Gerald, D. (1980) FEBS Lett. 116, 269-272; Wang, C.-L. A., Aquaron, R. R., Leavis, P. C., and Gergely, J. (1982) Eur. J. Biochem. 124, 7-12). Thus upon direct excitation with a laser the luminescence lifetimes of Eu1Ln1CaM and Tb1Ln1CaM provide information on the distance between sites I and II. On the other hand, since Tb3+ ions bound to sites III and IV are sensitizable through tyrosine residues, lifetime measurements of Tb2Ln2CaM excited by UV light yield the distance between sites III and IV. Both pairs of sites were found to be separated by a distance of 1.05 +/- 0.07 nm. Binding of Ca2+ to sites III and IV does not alter the distance between sites I and II. We have also attached a chromophoric label, dimethylaminophenylazobenzene, to Cys-133 of skeletal troponin I and carried out distance measurements on its complex with CaM by both direct and indirect excitation. The averaged distances from sites I and II in the N-terminal half and from sites III and IV in the C-terminal half of the CaM molecule to the label on troponin I are 2.7 and 2.5 nm, respectively.

Animals↗
PubMed1993

How far is it to the nearest hospital? Calculating distances using the Statistics Canada Postal Code Conversion File.

This report demonstrates how to calculate distances between points described in terms of latitude and longitude, using the Postal Code Conversion File (PCCF) and other files available from the Geography Division of Statistics Canada. Examples based on hospital data show how the results can be summarized in the form of tables, figures, or maps. Aerial distance to the nearest hospital is a crude but objective indicator of geographic accessibility to hospital services. Distances were calculated between enumeration area centroids for the population and blockface or enumeration area centroids for the hospitals. The median aerial distance to the nearest hospital facility in Canada was less than 3 km, while the mean distance was about 6 km. For teaching hospitals, the median aerial distance was a little less than 30 km, while the mean distance was a little more than 90 km. As most health files for administrative and research purposes contain postal codes, these techniques have potentially wide application.

Abstracting and Indexing↗
PubMed1993

Isolation by distance, trend surface analysis, and spatial autocorrelation.

The isolation by distance model is both a population process and a surface model. In this model the surface is, on average, flat in every direction. By contrast, probably most observed genetic surfaces exhibit trends generated by complex long-distance populational processes. When one estimates the parameters of a Malécot-Morton equation for those surfaces, the isolation by distance model does not fit. In the simplest case, in first-order trends (two-dimensional clines) the genetic differentiation increases dramatically, faster per unit distance than it would by isolation by distance alone. When isolation by distance takes place but is hidden through the apparent and complicated relief of a surface, another surface model incorporating trend spatial analysis can bypass the difficulty of estimating the isolation by distance process if approached through the Malécot-Morton equation or through a measure of spatial autocorrelation.

ABO Blood-Group System↗
PubMed1997

Fixation disparity and accommodation as a function of viewing distance and prism load.

Fixation disparity was measured with dichoptically presented nonius lines at viewing distances of 20, 30, 40, 60, and 100 cm, so that both vergence and accommodation were stimulated adequately as in normal vision. As the viewing distance was shortened, mean fixation disparity changed monotonically from 1 min arc eso (i.e., the eyes converged in front of the target) to 3 min arc exo. The average standard deviation of the psychometric function of fixation disparity, which is a measure of the temporal variability of vergence, was smallest at 100 cm (when fixation disparity was eso) and increased as viewing distance decreased. Fixation disparity itself and the change of fixation disparity with distance differed reliably among subjects with normal binocular vision, but neither was related to the momentary degree of accommodation. Fixation disparity was also measured at a constant distance of 40 cm, but with prisms in front of the eyes that induced the same vergence angles as viewing distances between 20 and 100 cm. The slope of these conventional fixation disparity curves as a function of prism load was generally larger than the slope of fixation disparity as a function of viewing distance (which can be explained by accommodative vergence), but the slopes of the two types of curves were correlated (r = 0.39, P = 0.02, n = 25).

Accommodation, Ocular↗
PubMed1996

Duration, distance, and speed judgments of two moving objects by 4- to 11-year olds.

Four- to 11-year-old children (N = 133) made duration, distance, and speed judgments on a Piagetian task where two cars ran on two parallel tracks. Special effort was made to make duration judgment tasks and distance judgment tasks comparable. Among younger children, difficulties of duration judgments and distance judgments were approximately the same. Additionally, temporal attributes had nearly the same effects on duration judgments as spatial attributes had on distance judgments, and spatial attributes had nearly the same effects on duration judgments as temporal attributes had on distance judgments. Among older children, distance judgments were easier than duration judgments, and the above-mentioned symmetry in effects of temporal and spatial attributes decreased somewhat. Temporal and spatial attributes affected speed judgments equally, across age groups.

Acceleration↗
PubMed1993

The effects of size, clutter, and complexity on vanishing-point distances in visual imagery.

The portrayal of vanishing-point distances in visual imagery was examined in six experiments. In all experiments, subjects formed visual images of squares, and the squares were to be oriented orthogonally to subjects' line of sight. The squares differed in their level of surface complexity, and were either undivided, divided into 4 equally sized smaller squares, or divided into 16 equally sized smaller squares. Squares also differed in stated referent size, and ranged from 3 in. to 128 ft along each side. After subjects had formed an image of a specified square, they transformed their image so that the square was portrayed to move away from them. Eventually, the imaged square was portrayed to be so far away that if it were any further away, it could not be identified. Subjects estimated the distance to the square that was portrayed in their image at that time, the vanishing-point distance, and the relationship between stated referent size and imaged vanishing-point distance was best described by a power function with an exponent less than 1. In general, there were trends for exponents (slopes on log axes) to increase slightly and for multiplicative constants (y intercepts on log axes) to decrease as surface complexity increased. No differences in exponents or in multiplicative constants were found when the vanishing-point was approached from either subthreshold or suprathreshold directions. When clutter in the form of additional imaged objects located to either side of the primary imaged object was added to the image, the exponent of the vanishing-point function increased slightly and the multiplicative constant decreased. The success of a power function (and the failure of the size-distance invariance hypothesis) in describing the vanishing-point distance function calls into question the notions (a) that a constant grain size exists in the imaginal visual field at a given location and (b) that grain size specifies a lower limit in the storage of information in visual images.

Adult↗
PubMed1999

The use of optical velocities for distance discrimination and reproduction during visually simulated self motion.

Successful navigation through an environment requires precise monitoring of direction and distance traveled ("path integration" or "dead reckoning"). Previous studies in blindfolded human subjects showed that velocity information arising from vestibular and somatosensory signals can be used to reproduce passive linear displacements. In these studies, visual information was excluded as sensory cue. Yet, in our everyday life, visual information is very important and usually dominates vestibular and somatosensory cues. In the present study, we investigated whether visual signals can be used to discriminate and reproduce simulated linear displacements. In a first set of experiments, subjects viewed two sequences of linear motion and were asked in a 2AFC task to judge whether the travel distance in the second sequence was larger or shorter than in the first. Displacements in either movement sequence could be forward (f) or backward (b). Subjects were very accurate in discriminating travel distances. Average error was less than 3% and did not depend on displacements being into the same (ff, bb) or opposite direction (fb, bf). In a second set of experiments, subjects had to reproduce a previously seen forward motion (passive condition), either in light or in darkness, i.e., with or without visual feedback. Passive displacements had different velocity profiles (constant, sinusoidal, complex) and speeds and were performed across a textured ground plane, a 2-D plane of dots or through a 3-D cloud of dots. With visual feedback, subjects reproduced distances accurately. Accuracy did not depend on the kind of velocity profile in the passive condition. Subjects tended to reproduce distance by replicating the velocity profile of the passive displacement. Finally, in the condition without visual feedback, subjects reproduced the shape of the velocity profile, but used much higher speeds, resulting in a substantial overshoot of travel distance. Our results show that visual, vestibular, and somatosensory signals are used for path integration, following a common strategy: the use of the velocity profile during self-motion.

Adult↗
PubMed2003

A stingless bee (Melipona seminigra) uses optic flow to estimate flight distances.

Foragers of a stingless bee, Melipona seminigra, are able to use the optic flow experienced en route to estimate flight distance. After training the bees to collect food inside a flight tunnel with black-and-white stripes covering the side walls and the floor, their search behavior was observed in tunnels lacking a reward. Like honeybees, the bees accurately estimated the distance to the previously offered food source as seen from the sections of the tunnel where they turned around in search of the food. Changing the visual flow by decreasing the width of the flight tunnel resulted in the underestimation of the distance flown. The removal of image motion cues either in the ventral or lateral field of view reduced the bees' ability to gauge distances. When the feeder inside the tunnel was displaced together with the bees feeding on it while preventing the bee from seeing any image motion during the displacement the bees experienced different distances on their way to the food source and during their return to the nest. In the subsequent test the bees searched for the food predominantly at the distance associated with their return flight.

Animal Communication↗
PubMed2005

Prey size selection and distance estimation in foraging adult dragonflies.

To determine whether perching dragonflies visually assess the distance to potential prey items, we presented artificial prey, glass beads suspended from fine wires, to perching dragonflies in the field. We videotaped the responses of freely foraging dragonflies (Libellula luctuosa and Sympetrum vicinum-Odonata, suborder Anisoptera) to beads ranging from 0.5 mm to 8 mm in diameter, recording whether or not the dragonflies took off after the beads, and if so, at what distance. Our results indicated that dragonflies were highly selective for bead size. Furthermore, the smaller Sympetrum preferred beads of smaller size and the larger Libellula preferred larger beads. Each species rejected beads as large or larger than their heads, even when the beads subtended the same visual angles as the smaller, attractive beads. Since bead size cannot be determined without reference to distance, we conclude that dragonflies are able to estimate the distance to potential prey items. The range over which they estimate distance is about 1 m for the larger Libellula and 70 cm for the smaller Sympetrum. The mechanism of distance estimation is unknown, but it probably includes both stereopsis and the motion parallax produced by head movements.

Animals↗