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At least 991 records · Page 55Linked to original sources

Mechanism of injury from air bag deployment loads.

Loadings induced by deploying currently representative air bags were studied with driver surrogates (anesthetized swine) leaning against the system during inflation. Torso injury mechanisms were studied in a physiologic model, supported against a static steering wheel-mounted air bag system. Severe and extensive chest and abdominal injuries to the swine were observed in the tests. Loading caused by air bag deployment can occur in either of two phases. The first phase represents the initial punch out of the bag from the module; the second phase represents the membrane force of the inflating bag. Statistical analysis indicated that punch out induced injury because of the high rate of loading to the surrogate body region in direct contact with the air bag module. Membrane forces induced injury by high compression over a larger area. Punch-out loading might be reduced by allowing the bag to escape from other parts of the container not in contact with the driver during deployment. Loading by the inflating bag might be reduced by using a compliant steering system to support the module. The amount and rate of generated gas had only marginal effect on the cumulative injury. Even an inflator with inadequate gas output to protect a properly seated occupant had sufficient energy to induce severe injuries in a surrogate in contact with the inflating module. Analysis of the field relevance of the results must consider not only the injury potential given that a driver is in direct contact with the air bag module at the time of deployment, but also the expected field frequency of such an event. Analysis of the field relevance of the results must also consider the correlation of the laboratory test environment with real-world exposure.

Abdominal Injuries↗

Appropriate frontal barrier tests for belted occupants.

Vehicle damage from frontal impacts was classified and investigated together with injuries sustained by belted front seat occupants. The sample consisted of 1872 frontal crashes from the Midlands of England. Analysis focused on impacts with broad objects that might conceivably be simulated by a barrier test. Two asymmetrical front-end damage patterns were commonly identified, and these gave the greatest rates of non-minor (Abbreviated Injury Scale (AIS) > or = 2) injuries in a range of Estimated Test Speeds from 35 to 52km/h which is the regime of current legislative crash tests. The most injurious type involved oblique damage caused by a substantial overlap of the struck object. The other type was from a small overlap. Objects struck and passenger compartment intrusions were compared. Appropriate asymmetrical and deformable barrier concepts were discussed. Other findings were connected with the future role of full face barriers as used in current tests such as Federal Motor Vehicle Safety Standard 208. Fuller overlaps (> 50%) tended to give more torso injuries rated > or = AIS 2 caused by seat belt loads and, at high speeds (53-79km/h), caused the most fatalities. Full overlaps (100%) rarely resulted in symmetrical intrusion into the passenger compartment.

Acceleration↗

Effects of retroreflector positioning on nighttime recognition of pedestrians.

This field study investigated potential effects of retroreflector positioning on recognition of nighttime pedestrians. The subject's task was to press a response button whenever he/she recognized a pedestrian on or alongside the road, while in a car with low-beam lamps on that was driven at a constant speed on a dark road. The results showed that each retroreflector configuration yielded significantly longer recognition distances than the no-retroreflector configuration. More importantly, the retroreflective markings attached to the limbs led to significantly longer (about 60-80%) recognition distances than when the retroreflective markings were attached to the torso. Furthermore, a pedestrian was more recognizable while crossing the road than while approaching the subject vehicle, except for configurations involving no retroreflective markings.

Accidents, Traffic↗

Application of body surface mapping to exercise testing: S-T80 isoarea maps in patients with coronary artery disease.

Body surface electrocardiographic maps were recorded before and after exercise in 25 men with angiographically documented coronary disease. Torso potential distributions at 192 locations were derived from a 32 lead electrode array using methods previously described in our laboratory. The S-T segment was characterized by the spatial distribution of the integral of S-T segment voltage over 80 ms (S-T80). Body surface regions where the S-T80 areas were =8 mV . ms or greater were identified in 18 of 25 patients. The most negative S-T80 site on the map was called the "S-T80 minimum." The S-T80 minima were located 1 or 2 electrode rows away from the standard V4--V6 electrode positions in 6 of 18 patients who developed S-T80 areas of -8 mV . ms or greater. Our data suggest that standard electrocardiographic leads may not be optimal for identifying S-T segment depression in all patients with coronary disease. Furthermore, body surface mapping during exercise provides a more quantitative and qualitative method for characterizing the ischemic response to exercise.

Adult↗

Non-Q-wave acute myocardial infarction: body surface potential map and ventriculographic patterns.

Day 5 body surface map and radionuclide angiographic patterns were compared among 56 patients with first non-Q-wave or Q-wave acute myocardial infarction (AMI). Three radionuclide angiographic patterns were recognized in patients with non-Q infarction: no wall motion abnormalities (n = 8), single-segment wall motion abnormalities (n = 10) and multiple-segment wall motion abnormalities (n = 9). In contrast, only 2 radionuclide angiographic patterns were identified in patients with Q-wave infarction: multiple-segment wall motion abnormalities (n = 25) and single-segment wall motion abnormalities (n = 4). The Q-wave distributions of 14 of 18 patients with non-Q infarction with 0 or 1 wall motion abnormalities were normal; 2 patients had "missed" anterior; 1 patient had inferior; and 1 had posterior AMI patterns. Of 9 patients with non-Q infarction who had multiple-segment wall motion abnormalities, 8 had infarct Q waves on the posterior torso. Q-wave patterns in patients with anterior (n = 17) and inferior (n = 12) Q-wave infarctions were typical and homogeneous for each group. Quantitative analysis of minimum Q-zone integral, sigma Q-wave integrals, ST-integral maximum, wall motion abnormality score and ejection fraction revealed no differences between patients with non-Q-wave and those with inferior Q-wave infarction. In contrast, patients with anterior AMI had significantly more abnormal values of all variables than either of the other groups. Overall, the data support the concept of non-Q-wave AMI as a distinct, if heterogeneous, pathophysiologic entity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Identification of best electrocardiographic leads for diagnosing left ventricular hypertrophy by statistical analysis of body surface potential maps.

In view of the increased risk of cardiovascular mortality associated with left ventricular (LV) hypertrophy, early recognition and quantitation of LV hypertrophy are important clinical goals. The standard 12-lead electrocardiogram is the easiest and most widely used noninvasive method for the diagnosis of LV hypertrophy; unfortunately, the diagnostic accuracy of commonly used electrocardiographic criteria remains unsatisfactory. Body surface potential maps contain diagnostic information not present in conventional lead systems. The present investigation combines the increased information content of surface maps with the power of multivariate statistical techniques in order to identify practical subsets of electrocardiographic leads that would allow improved diagnosis of LV hypertrophy. Discriminant analysis was performed on 120-lead data simultaneously recorded in 250 normal subjects and 214 patients with LV hypertrophy using as features instantaneous voltages on time-normalized P, PR, QRS and ST-T waveforms as well as the duration of these waveforms. Leads and features for optimal separation of 173 normal subjects aged greater than or equal to 30 years from 122 patients with pure LV hypertrophy were selected. A total of 6 features from 5 torso sites accounted for a specificity of 97% and a sensitivity of 94%. The single most potent discriminator was the duration of the P wave; voltages were measured in mid and late P on leads located in the lower left parasternal area, the left precordial region and the upper right back, in mid-QRS on a lead positioned 10 cm below V1 and slightly before the peak of the T wave on a lead in the lower left flank.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Body surface potential maps with low-level exercise in isolated left anterior descending coronary artery disease.

One hundred and twenty-lead body surface potential maps (BSPMs) were recorded at rest, at immediate cessation of exercise and after 1 (early) and 5 minutes (late) of recovery in 14 patients with isolated, critical, left anterior descending (LAD) coronary artery stenosis. Exercise endpoints, at an average peak rate of 98 +/- 13, were usual pain worsening in 13 LAD patients, and diagnostic ST depression in lead V5 in 1 patient. Twelve patients also had positive thallium scans. BSPMs were also recorded in 8 normal subjects who exercised to peak heart rates similar to those of the LAD subjects. Spatially, there were similar exercise changes in QRS and ST-segment integral patterns over the precordium and inferior torso in both groups. These were transient in the control group but persisted to late recovery in the LAD group, particularly for ST integral. Quantitatively, multivariate analysis revealed significant temporal differences between the 2 groups. However, the only independent BSPM variable was the sum of ST integral decrease, averaging --2,323 +/- 1,809 microV.s for normal patients between rest and immediate cessation of exercise, compared with -3,828 +/- 2,329 microV.s for the LAD patients (p less than 0.05). Late recovery minus rest difference averaged -1,264 +/- 1,080 microV.s for normal subjects and -2,575 +/- 1,844 microV.s for LAD patients (p less than 0.01). To control for the physiologic changes of exercise, the ST integral temporal differential maps of the normal subjects were subtracted from those of the LAD patients and the sum of negative intergroup differences was assumed to reflect only ischemia. Correlation of ST integral ischemia values at immediate cessation of exercise and late recovery was high (r = 0.88); however, intertechnique correlations of the BSPM variables with quantitative angiographic scores and thallium perfusion scan scores revealed generally low r values (range 0 to 0.52). These data demonstrate that ischemic repolarization changes are detectable and quantifiable by BSPM at low levels of cardiac stress in patients with 1-vessel disease when the usual electrocardiographic criteria of myocardial ischemia are frequently absent. The data further suggest that ST integral changes reflective of myocardial ischemia persist well after the exercise recovery period and that they are complementary to, rather than substitutionary for, other indirect measures of myocardial ischemia.

Adult↗

Improved prediction of left ventricular mass by regression analysis of body surface potential maps.

Electrocardiographic left ventricular (LV) hypertrophy involving ST-T abnormalities, in addition to high QRS voltages, is associated with increased risk of cardiovascular disease mortality. Unfortunately, conventional electrocardiographic criteria have limited utility in the quantitative assessment of LV hypertrophy. Body surface potential maps, which contain diagnostic information not present in commonly used lead systems, were recorded from 117 thoracic sites and 3 limb electrodes in 72 normal subjects and 84 patients with LV hypertrophy. Multiple regression analysis was performed separately for 54 women and 102 men on 120-lead data, using as features instantaneous voltages on time-normalized P, PR, QRS and ST-T waveforms. Leads and features for optimal prediction of echocardiographically determined LV mass were selected. A total of 6 features from 3 torso sites in men, and from the same 3 sites plus 2 others in women, yielded correlations between echocardiographic and electrocardiographic estimates of LV mass of 0.89 and 0.88, respectively. The standard errors of the estimate (SEE), or average errors in predicting LV mass from the regression equations, were 31 and 22 g, respectively. The single most potent predictor in both sexes was a mid-QRS voltage measured on a lead positioned 10 cm below V1; QRS duration, late QRS and early-to-mid T-wave amplitudes recorded in the lower left flank contributed significantly to the performance of both regression models. The optimal electrode sites for electrocardiographic prediction of LV mass were outside the conventional lead locations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Comparison of a vectorcardiographically derived 12-lead electrocardiogram with the conventional electrocardiogram during wide QRS complex tachycardia, and its potential application for continuous bedside monitoring.

Previous investigators published conflicting reports comparing a vectorcardiographically derived electrocardiogram (ECGD) with the conventional 12-lead one (ECG). Prior comparisons were obtained in adults during sinus rhythm, but never in patients with wide QRS complex tachycardia. The ECGD was evaluated during baseline rhythms in patients with varying cardiac diagnoses, and the diagnostic accuracy of the 2 methods was compared during 64 episodes of wide QRS complex tachycardia in 49 patients during cardiac electrophysiologic study. All leads of the 12-lead ECGD closely resembled the conventional ECG in baseline and tachycardia tracings, except leads V3 and V4. QRS voltages were less in the ECGD, resulting in an inability to detect left ventricular hypertrophy in one third of patients with that diagnosis. There was excellent agreement between the ECGD and ECG in diagnosing prior myocardial infarction (92%), ventricular preexcitation patterns (100%), bundle branch and fascicular blocks (100%), and axis deviation. The ECGD was equally as valuable as the ECG in the diagnosis of wide QRS complex tachycardia. There was perfect agreement between the 2 lead systems in application of the morphologic criteria differentiating supraventricular tachycardia with aberration from ventricular tachycardia in leads V1, V2 and V6, and for criteria requiring axis determination and measurement of RS intervals in the precordial leads. The ECGD tracings contained less muscle artifact during body movements (e.g., after direct-current defibrillation). In conclusion, the ECGD's close correlation with the ECG, and its technical superiority and simple 5 torso-positioned electrode configuration make it worth pursuing as an option for continuous bedside monitoring.

Adult↗

Rhythmical stereotypies in normal human infants.

Naturalistic, longitudinal observations of 20 normal infants biweekly during their first year showed that they performed a great quantity and variety of rhythmical and highly stereotyped behaviours. Forty-seven movement patterns are described involving the legs and feet; the head and face; the arms, hands, and fingers; and the whole torso in various postures. These behaviours showed developmental regularities as well as constancy of form and distribution. Groups of stereotypies involving particular parts of the body or postures had characteristic ages of onset, peak performance, and decline. The onset of particular stereotypy groups was highly correlated with motor development. It is proposed that rhythmical stereotypies are manifestations of incomplete cortical control of endogenous patterning in maturing neuromuscular pathways.

Age Factors↗

Air movement around a worker in a low-speed flow field.

A knowledge of the air movement around a worker in a low-speed airflow is important in a number of areas: containment testing of fume cupboards; testing of personal dust samplers; testing of LEV effectiveness; and measurement of worker exposure. Measurements of velocity vectors around the upper torsos of manikins and a human in low-speed airflows have been made using a laser Doppler anemometer. Both heated and unheated manikins, as well as a 'breathing' manikin were used. The results show that quite distinctive flow patterns develop with heated and unheated bodies. Comparison of the flows around two- and three-dimensional manikins with that around a human shows that only a three-dimensional heated manikin gives good results. The unheated breathing manikin gave results which were unrepresentative of the real situation. A suitable manikin for use in sampling or testing in low-speed airflows would have a heated, rounded, three-dimensional body of reasonably human dimensions and would be non-breathing and clothed.

Air Movements↗

Maximum acceptable lifting loads during seated and standing work positions.

The psychophysical method was used to determine the maximal acceptable load that eight males (age 22-30 years) would lift in each of four different positions: (1) seated, two-handed, symmetrical lift from a table, to a position 38 cm forward of the edge, (2) a seated lift from a position at the subject's side, on to a table in front of the subject involving a 90 degree twist of the torso, (3) standing, two-handed, symmetrical lift from the table, to a position 38 cm forward of the edge, and (4) standing, vertical lift from 86 above the floor. Subsequent to a training period, subjects lifted a tray with slotted handles at the rate of 1 or 4 lifts/min. Each subject chose the weight of the tray which was acceptable to him by adding or removing flat pieces of lead over a 45 min period. The weight of the tray, heart rate, and the perceived exertion were measured at 15, 30 and 45 min. Oxygen consumption was measured during the last 5 min of the 45 min experiment. Statistical analysis revealed a significant frequency and position effect. An increase in frequency from 1 to 4 lifts/min resulted in a decrease of 1.6 to 2.1 kg in the maximum acceptable weight for the various tasks. On average, the maximum acceptable weight of lift for standing positions was 16% greater than for sitting positions. Oxygen consumption and heart rate were significantly higher for 4 lifts/min than for 1 lift/min; however, the rating of perceived exertion did not differ for any factor.

Journal Article↗

Anthropometric contribution to standardising manikins for artificial-head microphones and to measuring headphones and ear protectors.

True-to-size head-torso manikins are required for research in the field of artificial-head stereophony as well as for testing and measuring headphones, soundproof helmets, ear protectors and other headgear. Attempts to design a manikin according to the available anthropometric data available proved to be difficult. By testing 77 men with technical jobs, 15 new quantities have been measured, some of them for comparison and some to complete existing measurements. The tests showed that it is absolutely essential to differentiate manikins of the desired qualities from an ethnic point of view. Manikins of different model dimensions should not be standardised according to percentiles but should represent typical head shapes. To this end, thorough measurements have to be made.

Journal Article↗

Predicting garment pattern dimensions from photographic and anthropometric data.

Traditional linear measurements (lengths and circumferences taken over the body surface with a tape measure) were compared with measurements of frontal and lateral view photographs for usefulness in determining pattern dimensions for the upper torso of the female body form. The statistical regression models developed indicated that, while linear measurements provided slightly more accuracy in predicting a few of the pattern dimensions, the photographic measurements were more accurate in predicting others, particularly pattern angles. Photographic measurements hold promise as an alternative to the more intrusive linear measurements for predicting pattern dimensions.

Journal Article↗

Forces applied to large hand wheels.

This is a report of a study conducted to establish the population isometric strength capabilities of subjects generating force using a hand wheel. Wheel force strength of 125 males and 125 females was measured using two different handgrip configurations: grasping the rim of the wheel and grasping the spoke. In addition, two separate procedures for generating and measuring strength were used: a 3 s average during a 6 s trial, and a ramp to maximum exertion level and then relax. The task simulated setting a handbrake on a typical railroad box car. Results indicated that grip characteristics and grip strength play an important role in isometric wheel force strength capabilities. The average tangential forces ranged from 393 to 614 N for males, and from 235 to 348 N for females, depending upon the grip configuration and the method used to measure strength. Standard whole-body strength measures for the legs, arms, torso and grip were also measured and demonstrated to be effective in predicting the wheel force strength capabilities of the subjects.

Journal Article↗

Three-dimensional uniform grid modeling of electrical defibrillation on a data parallel computer.

Finite element modeling has played an increasingly important role in the study of defibrillation. In order to model well the complex anatomical details, a large number of elements are required in the finite element grid, leading to a large set of equations that often cannot be solved effectively with the computational power of conventional computers. In this paper, we describe the use of a data parallel computer to provide the memory and reduction in solution time for solving these large finite element problems. Using a uniform grid and a nodal assembly technique, the discretized problem domain can be mapped efficiently to the parallel computer, allowing the solution of problems with over two million unknowns. The finite element algorithm for a three-dimensional inhomogeneous anisotropic body is described together with its parallel implementation. Test results for a canine torso model constructed from CT images are also presented.

Algorithms↗

Germline autonomy of maternal-effect mutations altering the embryonic body pattern of Drosophila.

Nine maternal-effect loci Drosophila melanogaster were tested in germline mosaics to determine whether the wildtype gene activity is required in somatic or germline components of the maternal ovary. Mutations in these loci affect the anterior-posterior or dorso-ventral body pattern. In all nine loci (torso, trunk, exuperantia, vasa, valois, staufen, tudor, dorsal, Toll) a mutant genotype in the germ cells is sufficient to produce all aspects of the mutant embryonic phenotype, even when those germ cells are surrounded by wildtype somatic tissues.

Animals↗

Maternal-effect genes that alter the fate map of the Drosophila blastoderm embryo.

The pattern of segmentation in the Drosophila embryo is controlled by at least 25 zygotically active genes and at least 20 maternally active genes. We have examined the pattern of expression of the protein product of the zygotically active segmentation gene fushi tarazu (ftz) at the cellular blastoderm stage in progeny of mutant females homozygous for each of six maternal-effect segmentation genes to observe the early effects of the maternal-effect genes on zygotic gene expression. The genes included exuperantia (a member of the anterior class of maternal-effect segmentation genes); staufen and vasa (members of the posterior class); and torso, trunk, and fs(1)N (members of the terminal class). Mutations in the genes caused a disruption of the normal pattern of ftz stripes in regions of the embryo where gene activity is known to be required. The ftz stripes provide a marker for segmental determination at the cellular blastoderm stage, making it possible to correlate aberrant patterns of ftz protein with defects in cuticle morphology at the end of embryogenesis. ftz protein expression in progeny of females mutant for combinations of the above genes was also examined. The changes in the ftz pattern in progeny of females doubly mutant for genes of the anterior and terminal classes or of the posterior and terminal classes can largely be understood as the result of the additive effects of the single mutations. In contrast, clearly nonadditive effects on the ftz pattern were seen when a mutation in a gene of the anterior class (exuperantia) was combined with mutations in posterior class genes.

Abdomen↗