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Biomedical subjects

W Barfield

Publications and source records attributed to W Barfield.

14 recordsLinked to original sources
PubMed1999

Cost consequences of implementation of an early obstetrical discharge programme in a military teaching hospital.

We evaluate the cost consequence of a voluntary early obstetrical discharge programme in a military teaching hospital. The study involved a control group of routine obstetrical discharge patients with uncomplicated vaginal delivery from March 1 to August 31, 1994 and the study group of early obstetrical discharge (24-48 hours) patients with uncomplicated vaginal delivery from March 1 to August 31, 1996. There were 1,042 total control patients with routine vaginal delivery totalling 2,668 hospital days with a mean number of hospital days of 2.56 per patient. The study group of early obstetrical discharge patients with uncomplicated vaginal delivery encompassed 1,050 patients with 1,965 hospital days with mean hospital days of 1.87 per patient (p < 0.05) without an increase in postpartum clinic or emergency room visits. The total cost of admissions (cost calculation of $1,221 per hospital day) fell from $3,257,628 in the routine discharge group to $2,399,625 in the early discharge cohort showing a total cost savings of $858,003 over the 6-months study period. The average cost per obstetrical admission for routine vaginal delivery fell from $3,126 per day to $2,285 per day without an increase in the postpartum paediatric adverse outcomes. Maternal postpartum readmission rates were statistically significantly increased (p < 0.05) in the study group at 0.6% with an OR[2.32(2.17, 6.92)] but all readmissions fell outside the 48-hour early discharge window. This programme showed significant cost savings without concomitant increase in paediatric or maternal adverse outcomes.

Aftercare↗
PubMed1999

Some virtual reality and telemedicine applications useful for long duration spaceflight from a systems engineering perspective.

This paper presents a review of virtual reality, telemedicine, and systems engineering design concepts that relate to the human performance of mission tasks during long duration spaceflight. A Mini-Case Study of the MIR/Progress collision is discussed and serves to highlight some of the key issues. We review some physiologic changes which occur as a result of long duration spaceflight, discuss issues associated with performing required mission tasks, and integrate concepts from telemedicine and virtual reality as possible methods and technologies to alleviate some of the deleterious effects of extended space missions.

Disasters↗
PubMed1998

Cost consequences of implementation of an early obstetrical discharge program in a military teaching hospital.

Objective: To evaluate the cost consequence of an early obstetrical discharge program in a military teaching hospital.Methods: The study involved a control group of routine obstetrical discharge patients with uncomplicated vaginal delivery from March to August 1994 and the study group of early obstetrical discharge (24-48 hours) patients with uncomplicated vaginal delivery from March to August 1996.Results: There were 1,042 total control patients with routine vaginal delivery from March to August 1994 totaling 2,668 hospital days with a mean number of hospital days of 2.56 per patient. The study group of early obstetrical discharge patients from March to August 1996 with uncomplicated vaginal delivery encompassed 1,050 patients with 1,965 days with mean hospital days of 1.87 per patient. The total cost of admissions (cost calculation of $1,221/hospital day) fell from $3,257,628 in the routine discharge group to $2,399,625 in the early discharge cohort showing a total cost savings of $858,003 over the 6-month study period. The average cost per admission fell from $3,126/day to $2,285/day without an increase in the postpartum pediatric or maternal adverse outcomes.Conclusion: An early obstetrical discharge program at a military teaching hospital showed significant cost savings without concomitant increase in pediatric or maternal adverse outcomes.

Journal Article↗
PubMed1997

Skilled performance on software as a function of domain expertise and program organization.

As part of a study on the recall of skilled and novice programmers, 23 subjects each viewed a 25-line BASIC program organized in one of three ways, executable order, random chunks, and random lines. Subjects performed a perceptual task in which they recopied a 25-line BASIC program on an answer sheet while the program remained in plain view, and a memory task, in which they recalled the BASIC program after a 4-min. exposure to it. For the perceptual task, the number of glances and amount of time per glance between the answer sheet and stimulus material were used as indices of recall. For the memory task, the number of lines recalled as a function of program organization and level of programming skill measured performance. Analysis indicated that skilled programmers encoded more lines of a program per glance and also spent less time examining each line of code than novices when the program was presented in executable order or random chunks. Further, skilled programmers recalled more lines of code than novices when the program was presented in executable order or random chunks but not in random lines. Implication of the results for the design of human-computer interfaces is discussed.

Educational Status↗
PubMed1996

Statistical analysis of accident severity on rural freeways.

The growing concern about the possible safety-related impacts of Intelligent Transportation Systems (ITS) has focused attention on the need to develop new statistical approaches to predict accident severity. This paper presents a nested logit formulation as a means for determining accident severity given that an accident has occurred. Four levels of severity are considered: (1) property damage only, (2) possible injury, (3) evident injury, and (4) disabling injury or fatality. Using 5-year accident data from a 61 km section of rural interstate in Washington State (which has been selected as an ITS demonstration site), we estimate a nested logit model of accident severity. The estimation results provide valuable evidence on the effect that environmental conditions, highway design, accident type, driver characteristics and vehicle attributes have on accident severity. Our findings show that the nested logit formulation is a promising approach to evaluate the impact that ITS or other safety-related countermeasures may have on accident severities.

Accidents, Traffic↗
PubMed1995

Effect of roadway geometrics and environmental factors on rural freeway accident frequencies.

This paper explores the frequency of occurrence of highway accidents on the basis of a multivariate analysis of roadway geometrics (e.g. horizontal and vertical alignments), weather, and other seasonal effects. Based on accident data collected in the field, a negative binomial model of overall accident frequencies is estimated along with models of the frequency of specific accident types. Interactions between weather and geometric variables are proposed as part of the model specifications. The results of the analysis uncover important determinants of accident frequency. By studying the relationship between weather and geometric elements, this paper offers insight into potential measures to counter the adverse effects of weather on highway sections with challenging geometrics.

Accidents, Traffic↗
PubMed1995

Judgments of azimuth and elevation as a function of monoscopic and binocular depth cues using a perspective display.

The purpose of this study was to investigate the use of three-dimensional display formats for judgments of spatial information using an exocentric frame of reference. Eight subjects judged the azimuth and elevation that separated two computer-generated objects using either a perspective or stereoscopic display. Errors, which consisted of the difference in absolute value between the estimated and actual azimuth or elevation, were analyzed as the response variable. The data indicated that the stereoscopic display resulted in more accurate estimates of elevation, especially for images aligned approximately orthogonally to the viewing vector. However, estimates of relative azimuth direction were not improved by use of the stereoscopic display. Furthermore, it was shown that the effect of compression resulting from a 45-deg computer graphics eye point elevation produced a response bias that was symmetrical around the horizontal plane of the reference cube, and that the depth cue of binocular disparity provided by the stereoscopic display reduced the magnitude of the compression errors. Implications of the results for the design of spatial displays are discussed.

Adult↗
PubMed1991

Effect of geometric parameters of perspective on judgements of spatial information.

15 university students performed an exocentric judgement task in which they estimated the azimuth and elevation separating two computer-generated cubes, using a perspective display. The perspective displays were created by varying two geometric parameters of perspective, the geometric field of view and station-point distance. Further, the radial distance separating the computer-generated images was varied. Analysis indicated that azimuth errors varied as a function of geometric field of view, radial distance, and station-point distance, while elevation errors varied as a function of geometric field of view and radial distance.

Adult↗
PubMed1990

Eccentricity, contrast, and angular extent as factors in the perception of peripheral apparent motion.

Two experiments were performed to investigate the perception of peripherally presented apparent motion as a function of eccentricity of the stimulus, ambient illumination, sex, stimulus pattern, and angular extent of stimulus presentation. The experimental task for both studies was to judge the direction of apparent motion for a stimulus target lighter than the background and presented on a Braumbach perimeter. The results from Exps. 1 and 2 indicated main effects for subjects and eccentricity. The combined results of Exps. 1 and 2 indicated main effects for eccentricity and angular separation of the apparent motion, however, the interaction between the two was not significant.

Adult↗
PubMed1987

Discriminating the structure of rotated three-dimensional figures.

Visualizing the structure of transformed (by rotation) three-dimensional (3-D) figures is an important aspect of information processing for computer-graphics tasks. However, little research exists to establish the speed and accuracy in which subjects perform discrimination tasks for transformed images and the effects of rotation variables on perceiving transformed images. This research tests the effects of figural complexity, angles and axes of rotation on the speed and accuracy in which subjects discriminate the structure of rotated 3-D wireframe images. Results show that response times are affected more by angles than axes of rotation, the specific form of the image affects error rates, and the number of 90 degrees bends which determine the structure of an image may be an inadequate measure of form complexity for the task described here.

Cues↗
PubMedDate not supplied

Relationship of factors affecting age of onset of independent ambulation.

Despite the standard available pediatric developmental scales and popular lore that girls walk at an earlier age than boys, no large-scale evaluation of the age of onset of independent ambulation has been previously published. The purpose of this study was the prospective epidemiologic evaluation of a large heterogeneous group of normal children to determine the effect of gender, race, birth order, and socioeconomic status on the age of onset of independent ambulation. The study cohort consisted of 986 children (575 male, 471 female). A multivariable analysis of covariance model was used to examine the effects of race, gender, income, and birth order on age at ambulation. After controlling for the other variables in the model, race was the only statistically significant predictor of age at ambulation (p < 0.0001), with black children walking at a younger age (10.9 +/- 2.1 months) than white children (11.6 +/- 2.3 months). Overall, the independent variables included in the model were only able to explain 2.5% of the variance of age at ambulation.

Black or African American↗
PubMedDate not supplied

The importance of extreme prematurity and low birthweight to US neonatal mortality patterns: implications for prenatal care and women's health.

OBJECTIVE: In order to frame the appropriateness of neonatal mortality reduction efforts that begin only after pregnancy is recognized, this study examined the relative contributions of different gestational age and birthweight groups to total neonatal mortality and to racial disparities in neonatal mortality in the United States. METHODS: Using the national linked birth/infant death data set for the 1988 cohort, the relative contributions of different birthweight and gestational age groups to national neonatal mortality rates were calculated. The relative contributions of these groups to the racial disparity in neonatal mortality were also assessed. RESULTS: Very low birthweight infants (< 1,500 g) accounted for 1.2% of all births, but 64.2% of all neonatal deaths. The very low birthweight rate for whites was 0.93%, while that for blacks was 2.79% with the contribution of this group to neonatal mortality higher for blacks than whites. Infants less than 1,000 g contributed more than 80% of the racial disparity in neonatal mortality. CONCLUSION: Neonatal mortality patterns in the United States have become highly dependent on infants with gestational ages that approach the second trimester. Preventing neonatal mortality by enhancing care only after pregnancy has been recognized, therefore, may be limited. Strategies that link prenatal care to broader initiatives to improve the health of women regardless of pregnancy status may be more effective.

Cohort Studies↗