Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Torso”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 613 records · Page 34Linked to original sources
PubMed2004

Preserved reticular neuronal activity during selective delivery of supra-clinical isoflurane concentrations to brain in goats and its association with spontaneous movement.

We have previously observed spontaneous movement when supra-clinical concentrations of isoflurane were selectively delivered to the in situ goat brain. We presently examined whether neurons in the midbrain reticular formation (MRF) remained active during such delivery. Isoflurane (5.1+/-1.6%) was selectively delivered to the goat cranial circulation while the torso isoflurane was decreased to 0.2-0.3%. At the high cranial/low torso isoflurane combination, spontaneous movement occurred that usually consisted of running motions, stiffening and twitching. Seventeen MRF neurons recorded in six goats exhibited high spontaneous firing (33+/-20 Hz) despite the presence of an isoelectric electroencephalogram. We conclude that some MRF neurons are resistant to the depressant effect of isoflurane, and may contribute to the observed spontaneous movement.

Action Potentials↗
PubMed2006

Touch down: the effect of artificial touch cues on orientation in microgravity.

Orienting oneself in space is not an easy task. On Earth, we combine visual, vestibular and pressure cues into a coherent concept of up and down. Since there are no cues from gravity in space, astronauts have to adjust the way they determine up from down, with the possible risk of space motion sickness. In three tasks performed by one astronaut in the International Space Station (ISS), we examined the effect of artificial touch cues presented to the torso. The role of "natural" touch cues on spatial orientation in microgravity, such as pressure presented to the sole of the feet, has already been shown, but it is not trivial whether the brain can also integrate artificial orientation information that has no real life equivalent. We find that artificial touch information in the form of a localised vibration on the torso that indicates down can make orienting in microgravity faster, better and easier. The importance of the artificial touch information seems to increase over the initial 7 days of staying in microgravity while the weight of visual information decreases over the same period. The results underline the capacity of the brain to adapt to unusual environments and to use and integrate artificial cues. Besides astronauts, pilots, divers and people with a vestibular dysfunction may benefit from this technology.

Cues↗
PubMedDate not supplied

Impact forces following the unexpected removal of a chair while sitting.

This report documents the impact forces measured during trials of dropping an anthropometric dummy (80.3 kg) (Hybrid III, First Technologies Corporation) in three different positions onto it's pelvis (gluteal region) from a seated height, which was meant to simulate a chair being pulled out from an individual in the process of sitting. Peak forces on the pelvis were measured by a force plate covered with industrial carpet. These impact forces were translated to the compressive and shear forces on the lumbar spine. The peak impact forces during the different body postures were 20000-29900 N (torso upright); 13000-22200 N (torso-legs 45 degrees to floor); 6000-15200 N (layout position). The impact forces generated from falling onto the pelvis from a seated height, appear to be sufficient to cause injury as the forces well exceed documented injury tolerance levels.

Accidental Falls↗
PubMed2000

Head restraints--the neglected countermeasure.

In a rear-end crash, if an occupant's head is unsupported it lags behind as the torso is accelerated forward. This causes the neck to change shape, first taking an s-shape and then bending backward in a 'whiplash' motion. This sudden differential movement of the head and torso can cause 'whiplash' injuries to the neck. This paper reviews methods to minimize the differential head/torso movement and reduce the resulting injuries, focusing on the necessary first step for prevention, which is a head restraint that is behind and close to the back of an occupant's head during the crash. The history of head restraints since the 1950s is reviewed, with particular attention to advanced restraint designs that are proving effective in reducing whiplash injury risk in dynamic tests using a new crash test dummy neck and a new neck injury criterion.

Accidents, Traffic↗
PubMed2000

Neck injuries in car collisions--a review covering a possible injury mechanism and the development of a new rear-impact dummy.

A review of a few Swedish research projects on soft tissue neck injuries in car collisions is presented together with some new results. Efforts to determine neck injury mechanisms was based on a hypothesis stating that injuries to the nerve root region in the cervical spine are a result of transient pressure gradients in the spinal canal during rapid neck bending. In experimental neck trauma research on animals, pressure gradients were observed and indications of nerve cell membrane dysfunction were found in the cervical spinal ganglia. The experiments covered neck extension, flexion and lateral bending. A theoretical model in which fluid flow was predicted to cause the transient pressure gradients was developed and a neck injury criterion based on Navier-Stokes Equations was applied on the flow model. The theory behind the Neck Injury Criterion indicates that the neck injury occurs early on in the rearward motion of the head relative to the torso in a rear-end collision. Thus the relative horizontal acceleration and velocity between the head and the torso should be restricted during the early head-neck motion to avoid neck injury. A Bio-fidelic Rear Impact Dummy (BioRID) was developed in several steps and validated against volunteer test results. The new dummy was partly based on the Hybrid III dummy. It had a new articulated spine with curvature and range of motion resembling that of a human being. A new crash dummy and a neck injury criterion will be very important components in a future rear-impact crash test procedure.

Accidents, Traffic↗
PubMed1981

Kicking, rocking, and waving: contextual analysis of rhythmical stereotypies in normal human infants.

I analysed the triggering contexts of over 14,000 bouts of rhythmical stereotypies of the legs, arms, and whole torso observed in 20 normal infants during their first year. Infant stereotypies were elicited by a wide variety of contexts including non-alert states, interactions with the caregiver and other persons, feeding situations, object interest, and kinaesthetic changes. The frequency of stereotypy in all contexts was a function of age. Non-alert states and interactions with the caregiver were disproportionately associated with leg and torso stereotypies. The relationship between these human stereotypies and the function and control of stereotyped behavior in other species is discussed.

Age Factors↗
PubMed2000

Motion times, hand forces, and trunk kinematics when using material handling manipulators in short-distance transfers of moderate mass objects.

The risk of musculoskeletal injury associated with manual materials handling tasks has led in part to the use of material handling manipulators, yet there is limited empirical data to facilitate selection, design, and evaluation of these devices. A laboratory study of two types of mechanical manipulators (articulated arm and overhead hoist) was conducted of short-distance transfers of moderate loads, and the influence of various task parameters and transfer method on motion times, peak hand forces, and torso kinematics was obtained. Use of manipulators increased elemental motion times for symmetric sagittal plane transfers by 36-63%, and asymmetric transfers (in the frontal plane) by 62-115%, compared to similar transfers performed manually. Peak hand forces were significantly lower with both manipulators (40-50%), and approximately 10% higher for asymmetric versus symmetric transfers. Overall torso kinematics were grossly similar with and without a manipulator. These results suggest that for self-paced job tasks, moderate mass objects will be transferred slower over short distances and with lower levels of external (hand) forces when using mechanical aids. These simple effects, however, were influenced by object mass and transfer height.

Adult↗
PubMed1997

A comparison of volume conductor effects on body surface Laplacian and potential ECGS: a model study.

The objective of this investigation is to study, using a computer model, the torso volume conductor effects on body surface potential electrograms and body surface Laplacian electrograms. A spherical volume conductor model was used to approximate the torso and the heart. Myocardial electrical events were approximated by two distributed dipole-layers representing activation wavefronts propagating from the endocardium to the epicardium. The present computer simulation results indicate that the body surface Laplacian maps provide enhanced performance over the body surface potential maps in resolving the configurations of two activation wavefronts over the anterior wall of the heart.

Body Surface Potential Mapping↗
PubMed2000

Back lift versus leg lift: an index and visualization of dynamic lifting strategies.

The description of a lifting strategy is typically provided in qualitative terms. A quantitative static descriptor or index differentiates the starting postures but not the primary moving segments. This technical note proposes an index that quantitatively characterizes different dynamic postural strategies employed during sagittal plane lifting. Dynamic lifting strategies are modeled in the velocity domain as different schemes of partitioning postural changes between the torso and leg segments. The index consists of two parameters, assigned to two leg segments, quantifying their contributions relative to the torso. Given a measured lifting movement, its index parameters values, ranging from 0.1 to 10, are estimated through an enumeration search process with the objective of minimizing the fitting error. The use of this index is illustrated by applying it to 24 lifting movements performed by six subjects assuming either a back-lift or a leg-lift strategy. Results indicate that a lifting strategy, in terms of whether the leg or the back is generally the prime mover, can be differentiated and visualized using this simple two-parameter index. In addition, indistinct intermediate strategies are also discerned, as the involvement of each segment in a lifting movement is quantified. The index is however limited in that it does not accommodate arm motion contributions to a lift nor possible time-dependent strategic changes during a lift. Potential future applications include time-efficient movement prediction and simulation for computerized biomechanical or ergonomic analysis.

Algorithms↗
PubMed2003

Biomechanical simulations of forward fall arrests: effects of upper extremity arrest strategy, gender and aging-related declines in muscle strength.

Computer simulation was used to predict the extent to which age-related muscle atrophy may adversely affect the safe arrest of a forward fall onto the arms. The biomechanical factors affecting the separate risks for wrist fracture or head impact were examined using a two-dimensional, 5-link, forward dynamic model. The hypothesis was tested in older females that age-related loss in muscular strength renders the use of the arms ineffective in arresting a forward fall without either a torso impact exceeding 0.5m/s or distal forearm loads sufficient to fracture the wrist. The results demonstrate that typical age-related decline in arm muscle strength substantially reduces the ability to arrest a forward fall without the elbows buckling and, therefore, a risk of torso and/or head impact. The model predicted that older women with below-average bone strength risk a Colles fracture when arresting typical falls, particularly with an extended arm.

Accidental Falls↗
PubMed1998

Removing swing from a handstand on rings using a properly timed backward giant circle: a simulation solution.

In the rings event in men's gymnastics, marks are deducted if the rings and gymnast are swinging during a held handstand position. The unwanted swing can be reduced in the next handstand position if the gymnast is able to properly time the start of the connecting giant circle. The purpose of this study was to search for the optimal time to commence a backward giant circle in order to attenuate swing in the succeeding handstand. Computer simulations, using a four-segment and a three-segment model which employed two-pulse muscular control strategies, were used to search for the optimal timing solution. Qualitative validation tests between the performance of a world class gymnast and the simulation models indicated that a three-segment model comprising a cables-rings segment, an arms segment with a shoulder torque generator, and a head-torso-legs segment, produced similar results to that of a four-segment model which separated the legs segment from the torso and employed an additional torque generator at the hip joint. The results from the simulation indicated that a gymnast should be advised to initiate a backward giant circle when his swinging handstand has reached the bottom of its swing-arc. For a handstand with an original swing-amplitude of 10 degrees, the simulation results indicate that a properly timed backward giant circle can reduce this amplitude to a negligible 1.5 degrees of swing.

Biomechanical Phenomena↗
PubMed1995

Reconstruction of the standard 12-lead ECG from recordings using nonstandard activity-compatible proximal limb lead positions.

Proximal or torso placement of limb leads in the 12-lead electrocardiogram (ECG) has been shown to influence the appearance of QRS waveforms considerably. A method was developed for computer-based reconstruction of standard-like waveforms from nonstandard torso-recorded waveforms. Reconstruction coefficients required by the method were determined using ECG data obtained from 30 patients. The coefficients were then applied on an independent test set of 100 patients. In 21 of these patients, a second standard EGG was obtained the next day to determine the day-to-day variation in QRS waveforms. R wave amplitudes in leads I and II, and electrical axes in the frontal plane were measured in the standard ECG, the nonstandard ECG, and the reconstructed ECG. It is shown that the reconstruction method yields ECGs that differ less from standard than do two standard ECGs recorded on consecutive days. The performance of the reconstruction method was not influenced by age, sex, height, or weight.

Adult↗
PubMed1994

Remodeling in myocardial infarction and body surface potential maps.

This study deals with the capabilities of body surface integral and departure maps to evaluate the chronic stage of myocardial infarction based on dividing the left ventricle into 12 segments. The effects of ventricular remodeling on electrocardiographic potential distributions are considered. A 61-year-old male patient was examined five times by body surface potential mapping during a period of 9 months after acute myocardial infarction. Integral maps were calculated for 60 ms after QRS onset and compared with mean data from a control group using departure maps. Integral maps showed a continual reduction of negative potentials in the lower half of the torso with time. The negative area covered the lower torso in the departure maps during the whole study, but its form and value changed. According to the location of the departure area, the surface projection of the scar moved from a position corresponding to inferior segments to a position corresponding to posterior segments. Its size also decreased. Echocardiographic examinations showed progressive enlargement of both ventricles with time. Therefore, the authors postulate that the changing pattern of body surface potential maps was mainly influenced by ventricular remodeling after myocardial infarction.

Electrocardiography↗
PubMed1977

The electrocardiographic image surface revisited.

An image torso may be viewed as a one-to-one transform of a physical volume conductor to a geometric form which defines both the axis and sensitivity of any electrocardiographic connection. In this report, the image surfaces of laminar, spherical, rectangular and humanoid physical torsos are explored theoretically and experimentally. All proved to be rounded or spherical in form despite the marked differences in the configuration of the physical conductor. Moderate degrees of dipole eccentricity induced only small departures from this basic circular pattern. Introduction of phase inhomogeneity, however, resulted in more striking deviations from roundness.

Animals↗
PubMed1984

Electrocardiographic effects of myocardial ischemia induced by atrial pacing in dogs with coronary stenosis. II. Comparison of S-T segment and QRS changes in dogs with left circumflex arterial narrowing.

The effects of tachycardia on the QRS complex in the absence and in the presence of coronary arterial constriction are of possible clinical significance. To study the spatial and temporal distributions of these effects, a canine model simulating progressive coronary occlusion was studied. Tachycardia was induced by atrial pacing, coronary narrowing was produced by implantation of an ameroid constrictor about the left circumflex coronary artery and electrocardiographic effects were studied by isopotential mapping techniques at rates of up to 250 beats per minute, one to three weeks after constrictor implant. In five dogs. pacing without coronary constriction demonstrated the spatial and temporal dependence of QRS changes; tachycardia-induced changes varied from one torso site to another at any instant, and from one moment to another at any one torso location. Patterns in ten dogs with constrictors were dependent upon time after ameroid placement. Resting QRS and S-T segment distributions remained unchanged. One week after surgery, QRS and S-T segment patterns during pacing were as in controls. Two weeks after surgery, QRS patterns were as in controls but flat S-T segment depression resulted at high rates. After three weeks, QRS patterns during pacing were abnormal and S-T segment depression was observed. At each of the later times, the QRS response was similar at rates which did and which did not cause S-T depression. Thus, the effects of tachycardia on excitation and recovery forces in the presence of restricted coronary flow are independent of one another. This suggests that the two responses to ischemia may be due to different basic mechanisms and, hence, that their detection may reflect different myocardial abnormalities.

Animals↗
PubMed1988

The effect of variations of ventricular volume on the electrocardiogram. A comparison of two model simulations.

Two previously published models of the electrocardiogram are compared and evaluated to determine the causes and nature of the relationship between variations in ventricular volumes and surface potential. Both models included a relatively high conductivity spherical heart in a spherical torso, but in one the source was a single dipole, while in the other the source was a double-layer spherical cap. Volume conductor effects (that is the change in electrical conductivity of the torso associated with ventricular volume changes) caused a decrease in surface potential with increase in ventricular volume. Changes in position of the heart and of the strength of the activation wavefront with increases in volume may explain the increase in surface potential with ventricular volume observed in experimental studies.

Cardiac Volume↗
PubMed1994

Analysis of PTCA-induced ischemia using an ECG inverse solution or the wavelet transform.

In patients without significant collaterals, percutaneous transluminal coronary angioplasty (PTCA) produces acute transient ischemia that is detectable in both standard electrocardiograms (ECG) and body surface potential maps (BSPMs). Control recordings made before or between inflations provide personalized baselines, which isolate the effects of ischemia from interpatient differences, such as torso shape and electrode location. In this study, two methods of evaluating PTCA-induced ischemia from BSPM recordings are presented. In the first method, an ECG inverse solution that estimates epicardial potentials from body surface signals using a realistic model of torso geometry is applied. The strength of this method lies in its potential ability to localize areas of cardiac ischemia on the epicardial surface. In the second approach, wavelet transforms were used to perform a multiresolution decomposition of the BSPM data into different frequency bands. The basis functions of the wavelet transform are time-limited and narrow band and hence can be expected to be sensitive to features of the BSPM that originate in discrete electrophysiologic events, such as intrusion of the activation front onto regions of ischemia or arrhythmias due to local conduction abnormalities. The method also offers a means of temporal and frequency localization of cardiac events related to the initiation of injury currents and abnormal conduction due to PTCA-induced ischemia. The inverse solution and the wavelet transform each offer new views of the spatial and temporal courses of acute ischemia potentially leading to new diagnostic insights in ECG patient examination.

Angioplasty, Balloon, Coronary↗
PubMed1994

Assessment of spatial and temporal characteristics of ventricular repolarization.

Measurement of dynamics and spatial characteristics of ventricular repolarization is of interest in assessing patients with ischemic heart disease, particularly in relation to the detection and characterization of ischemic events, identification of patients at risk of ventricular arrhythmias, or determination of the efficacy of drugs intended to alter repolarization. The QT interval (QTI) has been the index of choice for assessing repolarization abnormalities. It is a general measure of repolarization duration but lacks the power to assess the spatial aspects of repolarization and the ability to detect localized shortening in the setting of global prolongation. For direct cardiac surface measurement, QRST integrals and activation recovery intervals (ARIs) were used to assess repolarization and its disparity. The use of similar measurements from the body surface was proposed to provide better characterization of repolarization, its disparity, and its dynamics than is possible using the QTI. In one open-chest experiment using an intact canine heart and two experiments using isolated canine hearts suspended in a torso-shaped electrolytic tank, 64 epicardial electrograms and 192 torso surface electrocardiograms were measured simultaneously. Ventricular repolarization was globally altered by varying pacing cycle lengths or tank temperature. Atrial and ventricular pacing were used to assess sensitivity of repolarization indices to activation sequence. At the cardiac surface, (1) QTI tracks global repolarization changes but is affected by activation sequence and insensitive to localized shortening of repolarization; (2) distribution of QRST integrals reflects disparity of repolarization and is largely independent of activation sequence; and (3) ARI measures local repolarization duration and is only weakly affected by activation sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗