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This report compares experimentally-obtained headlamp visibility distances with stopping distances from 88 km/hr. The results indicate that low-beam headlamps are inadequate for safely revealing low-contrast objects at legal driving speeds.
The partial transmission zone (PTZ) measured in air and its radiation shadow components are identified quantitatively and qualitatively for both cuboid and beam-divergence-shaped blocks. Source-block distance (SBD) and source-surface distance (SSD) are varied to produce SBD/SSD ratios from 0.71 to 0.86. The variation of the magnitude of the radiation shadow components as a function of SBD/SSD is explained in terms of a radiation shadow model. The clinical significance of PTZ minimization and a comparison between PTZs of 'shaped' and 'nonshaped' blocks is discussed. For small ratios of SBD/SSD the beam-divergence-shaped blocks produce smaller medial and lateral PTZs, whereas for larger ratios in the order of 0.9 the medial PTZ is also small for the cuboid blocks. Both PTZs, in general, decrease with increasing SBD/SSD ratios and for both cuboid and beam-divergence-shaped blocks.
Eyeball protrusion is one characteristic that must be assessed/predicted in craniofacial identification methods of skull-face superimposition and facial approximation. Previously it has been suggested that average exophthalmometry values, as measured on living individuals, should be used. However, it is unknown if proptosis prediction can be improved beyond the accuracy obtained when using mean values. Some authors have suggested that relationships between exophthalmos, height, interpupillary distance, and interorbital distance exist and it has been reported that these latter variables can be used to estimate eyeball projection. However, crucial tests are yet to be conducted. This study measures these variables and tests the accuracy of exophthalmometry means, a previously proposed prediction equation, and newly derived regression equations to determine which methods provide the best results. Data indicate that variation in exophthalmos is fairly small and as such prediction from other variables, like body height, are weak; thus, exophthalmometry means currently offer the best practical method of prediction. It should be noted that up to 2 mm error from either side of the mean is expected for 68% of cases.
BACKGROUND AND RATIONALE: Preoperative evaluation is important in the detection of patients at risk for difficult tracheal intubation. Thyromental distance (TMD) is often used for these purposes, but its value as an indicator for difficult intubation is questionable, as it varies with patient size and body proportions. The purpose of the present study was to evaluate and compare the accuracies of the ratio of patient's height to TMD (ratio of height to TMD = RHTMD) and TMD alone in the prediction of difficult tracheal intubation in Thai patients. MATERIAL AND METHODS: The authors collected data on 382 consecutive patients scheduled to receive general anesthesia requiring endotracheal intubation for elective surgery. Thyromental distance and RHTMD were evaluated preoperatively. Difficult intubation was defined in the present study by Cormack and Lehane grade 3 or 4. The optimal predictive value was chosen using a receiver operating characteristic (ROC) curve. The areas under the ROC curves (AUC) of TMD and RHTMD were compared to determine the performance of the different predictive tests used. The sensitivity, specificity, and positive and negative predictive values of each of the predictive tests were calculated according to standard formulae. RESULTS: Difficult intubation occurred in 42 patients (10.9 %). The predictive advantage of RHTMD has a similar specificity with improved sensitivity in comparison with TMD. The AUC of RHTMD was significantly greater than the AUC of TMD (p = 0.00). The authors concluded that RHTMD had better accuracy in predicting difficult intubation than TMD.
Estimated are the distances between the nasolacrimal duct and the Canalis palatinus major on the side-wall of the nose cavity. Included are measurements of distances of the Ostium pharyngeum tubae auditivae to the Canalis palatinus major and the upper surface of the Palatum molle.
The ABO and Rh systems of the population in 26 residential units in the province of Ferrara were studied to detect the effect of genetic drift on the differentiation of gene frequencies. Results obtained from principal components analysis and dendrograms were similar. A significant correlation between genetic and geographic distance was found. It was therefore hypothesized that in the area of Ferrara children born to parents originating from different communes were heterozygous at more loci than children born to parents originating from the same commune. It was also thought that it may be possible to use geographic distance between birthplaces of parents as an indicator of hybridity in their children.
In three experiments, we independently manipulated the angular disparity between objects to be compared and the angular distance between the central axis of the objects and the vertical axis in a mental rotation paradigm. There was a linear increase in reaction times that was attributable to both factors. This result held whether the objects were rotated (with respect to each other and to the upright) within the frontal-parallel plane (Experiment 1) or in depth (Experiment 2), although the effects of both factors were greater for objects rotated in depth than for objects rotated within the frontal-parallel plane (Experiment 3). In addition, the factors interacted when the subjects had to search for matching ends of the figures (Experiments 1 and 2), but they were additive when the ends that matched were evident (Experiment 3). These data may be interpreted to mean that subjects normalize or reference an object with respect to the vertical upright as well as compute the rotational transformations used to determine shape identity.
INTRODUCTION: Assessment of students at distance, in a course with over 20 units (subjects), provides special challenges in providing timely, accurate and detailed feedback both formatively and summatively. METHOD: A description of assessment practices including reflective journals, essays, critical appraisal of literature, case studies or teaching presentations in video and written format, clinical audits, and large research projects is provided. The impact of a multitude of criterion-referenced methods of students, teachers and administrative services as well as quality assurance issues are measured. CONCLUSION: Students preferred multiple levels of formative and summative assessment using criterion referencing to exams. These methods were thought to be contextually relevant to clinical practice and examined knowledge, cognition and performance appropriately. Length of assessment task, difficulty with English as a second language and lack of detail or clarity on written feedback posed problems for a number of students. Quality assurance procedures have been put into place to rectify some of these problems.
Fields such as medicine, biomechanics or ergonomics need to measure the positions and the rotational movements of body segments. The aim of this article is to underscore the problem of imperfection on angle measurement using a three-dimensional television system. First, the error on a single angle value is assessed through the classical Taylor's formula and through a simulating approach. Then the error is considered for an entire signal through either an experimental design or a simulating approach. To take into account such an error when comparing two angle multidimensional signals, a specific coding technique is suggested. Finally, two graphical patterns are proposed to show globally the distance between the signals with regard to the error.
The distance between the area pterionalis and the optic nerve, the depth of the recess of for the temporal pole and the form of the lateral part of the sphenoidal wing are described.
Radiation beam characteristics are usually obtained by scanning in a water phantom. Central axis depth dose data, beam profiles, and isodose curves are derived from these measurements. Certain treatment planning systems require that beam profiles be scanned isocentrically rather than at a constant source-surface distance. We have looked at profiles taken both ways, with appropriate field-size correction, and find no significant difference between them. This should simplify data acquisition in many cases.
In 215 outpatients suffering from occlusive arterial disease of the lower limbs the authors compared the decrease in the ratio of ankle systolic pressure to brachial systolic pressure according to whether the treadmill exercise was limited to one minute or extended until pain forced the patient to stop. After a one-minute walk the pressure index always decreased significantly, especially when walking was restricted. The decrease in the pressure index was generally greater when the exercise was continued until the absolute walking distance, and the recovery time was usually twice as long. The fall in the pressure index was significantly greater for patients with single and multiple iliac stenoses than for those with stenoses at lower levels. In patients having a diastolic blood flow velocity on Doppler curves at rest, not modified by walking, a maximum drop in peripheral pressure was recorded after walking for one minute. In this instance there was no intensification of the decrease in peripheral pressure, unlike in patients without a diastolic blood flow velocity at rest. This one-minute test is not a maximal hemodynamic response, but it is sufficient for the appreciation of ischemia during exercise, according to the different parameters measured.
The velocity of a 15-meter walk and walking endurance (distance covered in 6 minutes) are considered distinct outcomes in clinical trials of stroke rehabilitation. Comfortable velocities used for each task in 24 subjects with chronic hemiparesis were not significantly different, however. Although speed and endurance did not reflect different domains of efficacy in outpatients whose usual speed was >0.5 m/s, the fastest feasible 15-meter velocity augmented these measures.
Quality of the environment is crucial for human health. Environmental hazards may lead to adverse health effects, while a sound environment can support of enable health. It has been clear that health and environment must be understood within the context of social and economic development, which was stressed especially in the Earth Summit held in Rio de Janeiro, Brazil, in 1992. Investing in improvement of people's health and their environment is a prerequisite for sustainable development. The telecommunication revolution enables distance learning without frontiers in a reansparent and interactive environment. Applying the Internet and other telecommunication into public health including environmental health holds the greatest promise for global health. A wide application and access would facilitate and expedite the reduction of inequity prevailing between the south and north in an unprecedented speed. This proposed course is thus designed to provide an overview on health and environment in sustainable development through the Internet.
In this study erythrocytes drawn from well-trained athletes (middle- and long-distance runners) and from sedentary subjects have been compared for their adenine nucleotide contents. ADP and AMP appeared to be significantly (p less than 0,001) increased only in red cells from athletes in the rest state. After athletes' race this difference with control subjects become insignificant. Nevertheless, the observed ADP and AMP modifications are not great enough to influence the energy charge (CE) of the compared erythrocytes.
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INTRODUCTION: Course evaluation is essential for continuous enhancement of teaching. This evaluation aimed to assess the impact of the Graduate Diploma of Family Medicine on the clinical practices, community activities, learning styles and personal lives of its graduates. METHODS: Cross-sectional postal questionnaire survey of all 1993 to 1997 graduates of the Graduate Diploma in Family Medicine (n = 233). RESULTS: A response rate of 70% was achieved. Male respondents felt that they treated a greater variety of conditions (p = 0.04), had undertaken more procedural work (p = 0.03), and had increased procedural confidence (p = 0.009) compared to female respondents, while the female respondents referred more (p = 0.03). Solo practitioners tended to look for evidence in clinical decision making (p = 0.006) and applied critical appraisal techniques when reading medical information provided by pharmaceutical representatives (p = 0.04). Group practitioners tended to participate in more research projects (other than drug trials) than solo practitioners (p = 0.03). There was a difference between full and part time general practitioners, even after controlling for gender, with the former more certain that general practice is where they wanted to be (p = 0.005), they also felt more competent in interpreting data, e.g. ECGs (p = 0.013). More male students indicated they preferred a reflective learning style than females (p = 0.04). CONCLUSION: The clinical electives of the Graduate Diploma in Family Medicine had the most significant impact on the clinical practices of full time GPs who were predominantly male graduates. Gender differences were apparent in styles of practice as males tended to conduct more procedural work, while female graduates preferred the gatekeeper role and referred more. The course also impacted on the students' approach to evidence in their clinical decision making. They were more critical of medical information provided by pharmaceutical representatives who are one of the major sources of CME for many GPs. Future evaluations should be based on experimental and quasi-experimental designs in order to measure changes in student perceptions and clinical practice, as well as more objective measures of learning styles.
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