Search results for "VELOCITY"
showing 10 items of 881 documents
Changes in accommodative responses with multifocal contact lenses: a pilot study.
2011
Our aim was to evaluate induced changes in pupil and accommodative response for different accommodative stimuli with three different multifocal contact lenses (CLs). Accommodative and pupil responses with three aspheric multifocal CLs of simultaneous focus center near (PureVision Low Add, PureVision High Add and Focus Progressives) for two accommodative stimuli of -2.5 and -4.00 D were recorded in 10 young subjects. Accommodative response, peak velocity, and time constant of accommodation and pupil constriction were assessed. The measurements were evaluated in all the participants with distance-single vision CLs and with the three multifocal CLs. The monocular measurements were performed in…
The preoperative assessment of stroke risk in lesions involving the internal carotid artery.
1995
Patients with vascular or tumourous lesions involving the internal carotid artery are at risk of damage or occlusion of this vessel during surgical or endovascular procedures. To assess the stroke risk transcranial Doppler aided carotid compression tests were performed in 82 patients. Based on changes of blood flow velocity (BFV), pulsatility index, systolic/diastolic ratio and length of transient hyperaemic response three groups could be differentiated. Patients in group A (31%) showed only a slight reaction of BFV and were at minimal risk in case of carotid occlusion. Patients in group B (52%) underwent a distinct decrease of Doppler readings with partial improvement and were considered t…
The influence of ageing on the force-velocity-power characteristics of human elbow flexor muscles.
2003
Abstract The purpose of this study was to quantify the effects of ageing on the maximal power ( P max ) of the elbow flexor muscles and to determine the impact of velocity on the loss of power in older people. Sixteen elderly subjects (7 men and 9 women, age range 61–78 years) and 17 young subjects (11 men and 6 women, age range 18–27 years) participated in this study. Maximal elbow flexions were performed against increasing inertia. The maximal force ( F max ), maximal shortening velocity ( V max ), P max , dynamic constants ( a , b and a / F max ), optimal force ( F opt ), optimal velocity ( V opt ) and V opt / V max were determined from Hill's equation. Myoelectrical activity (EMG) of th…
Central motor conduction time by magnetic stimulation of the cortex and peripheral nerve conduction follow-up studies in Friedreich's ataxia.
1998
A follow-up clinical study, peripheral motor and sensory nerve conduction velocities and central motor conduction by magnetic stimulation of the cortex were performed in 13 patients with classical Friedreich's ataxia (FA) phenotype, for a period of 9-12 years. Clinical worsening was unrelated to peripheral nerve abnormalities. The amplitude of the nerve action potentials and delayed conduction velocity remained unchanged for several years. Central motor conduction times were abnormal in all patients. Clinical conditions worsened significantly between successive examinations with significant increments in threshold and significant decrement of the amplitude of motor evoked potentials. The re…
Measurement of the local aortic stiffness by a non-invasive bioelectrical impedance technique.
2011
International audience; Aortic stiffness measurement is well recognized as an independent predictor of cardiovascular mortality and morbidity. Recently, a simple method has been proposed for the evaluation of the local aortic stiffness (AoStiff) using a non-invasive bioelectrical impedance (BI) technique. This approach relies on a novel interpretation of the arterial stiffness where AoStiff is computed from the measurement of two new BI variables: (1) the local aortic flow resistance (AoRes) exerted by the drag forces onto the flow; (2) the local aortic wall distensibility (AoDist). Herein, we propose to detail and compare these three indices with the reference pulse wave velocity (PWV) mea…
Dose-dependent effects of decaffeinated coffee on endothelial function in healthy subjects
2009
ackground/Objectives: Coffee is known to contain antioxidant substances whose effects may be blunted because of caffeine that may unfavorably affect the cardiovascular system. This study was designed to investigate the acute dose-dependent effects of decaffeinated coffee (DC) on endothelial function measured by the brachial artery flow-mediated dilation (FMD). Subjects/Methods: A total of 15 (8 men and 7 women) healthy nonobese subjects underwent a single-blind, crossover study. Subjects ingested one and two cups of decaffeinated Italian espresso coffee in random order at 5- to 7-day intervals. Results: In the hour following the ingestion of two cups of DC, FMD increased (mean±s.e.m.): 0 mi…
Noninvasive assessment of pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension by high temporal resolution phase-con…
2013
Background— Right heart catheterization is the gold standard for assessment of pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension. To date, MRI has not been able to produce precise measurements of mean pulmonary arterial pressure (mPAP). The purpose of the study was to create a model for estimating mPAP and pulmonary vascular resistance in patients with chronic thromboembolic pulmonary hypertension by high temporal resolution phase-contrast MRI (PC-MRI) and to correlate the results with simultaneously acquired, invasive catheter-based measurements (simultaneously measured mPAP) and with right heart catheterization measurements. Methods and Results— A tota…
Left ventricular diastolic filling alterations in subjects with mitral valve prolapse: A Doppler echocardiographic study
1993
To assess left ventricular diastolic filling in mitral valve prolapse (MVP), we studied 22 patients with idiopathic MVP and 22 healthy controls matched for sex, age, body surface area and heart rate. A two-dimensional, M-mode and Doppler echocardiographic examination was performed to exclude any cardiac abnormalities. The two groups had similar diastolic and systolic left ventricular volumes, left ventricle mass and ejection fraction. Doppler measurements of mitral inflow were: E and A areas (the components of the total flow velocity-time integral in the early passive period of ventricular filling, E; and the late active period of atrial emptying, A), the peak E and A velocities (cm.s-1), a…
Analysis of F-wave in metabolic neuropathies: a comparative study in uremic and diabetic patients.
1987
Motor nerve conduction study along the entire length of the ulnar and tibialis posterior nerves was carried out in 30 diabetics compared with 30 uremic patients and 30 control subjects. The conduction in the proximal and the distal nerve segments was evaluated by the determination of the M and F latencies, MNCV (between the stimulus sites), FWCV (between the spinal cord and the stimulus sites), and F-ratio (conduction time ratio of proximal to distal segment). In both groups of patients the lower limbs appear much more involved than the upper, where the ulnar nerve is more commonly affected in uremic than in diabetic patients. In diabetic neuropathy the motor conduction abnormalities are di…
Impact of environmental temperature on skin thickness and microvascular blood flow in subjects with and without diabetes.
2006
Glucose measurement from different skin areas might be influenced by changes in skin texture due to several environmental confounders. Our study was performed to investigate the effect of changes in ambient temperature on skin thickness and microvascular skin blood flow in subjects with and without diabetes at the lower forearm.Thirteen subjects with diabetes and seven without diabetes participated in the study. The investigations were performed in a temperature- and humidity-controlled climatic chamber (EMPA, St. Gallen, Switzerland). Starting at 25 degrees C, the environmental temperature was changed in 4 degrees C steps every 40 min. Skin thickness was measured by an ultrasonic reflectio…