Biomedical subjects

G T Foster

Publications and source records attributed to G T Foster.

5 recordsLinked to original sources

PubMed2007

Atom interferometer measurement of the newtonian constant of gravity.

We measured the Newtonian constant of gravity, G, using a gravity gradiometer based on atom interferometry. The gradiometer measures the differential acceleration of two samples of laser-cooled Cs atoms. The change in gravitational field along one dimension is measured when a well-characterized Pb mass is displaced. Here, we report a value of G = 6.693 x 10(-11) cubic meters per kilogram second squared, with a standard error of the mean of +/-0.027 x 10(-11) and a systematic error of +/-0.021 x 10(-11) cubic meters per kilogram second squared. The possibility that unknown systematic errors still exist in traditional measurements makes it important to measure G with independent methods.

Journal Article↗

PubMed2001

Patient-ventilator asynchrony.

The basic mechanism of patient-ventilator asynchrony is the mismatching between neural inspiratory and mechanical inspiratory time. Alterations in respiratory drive, timing, respiratory muscle pressure, and respiratory system mechanics influence the interaction between the patient and the ventilator. None of the currently available partial ventilatory support modes are exempt from problems with patient-ventilator asynchrony. Ventilator triggering design in the trigger phase and the set variables in the post-trigger phase contribute to patient-ventilator interaction. The set inspiratory flow rate in the post-trigger phase for assist-control volume cycled ventilation affects patient-ventilator asynchrony. Likewise, the initial pressure rise time, the pressure support level, and the flow-threshold for cycling off inspiration for pressure support ventilation are important factors affecting patient-ventilator asynchrony. Current investigations have advanced our understanding in this area; however, its prevalence and the extent to which patient-ventilator asynchrony affect the duration of mechanical ventilation remain unclear.

Humans↗

PubMed2001

Hemoptysis due to migration of a fractured Kirschner wire.

We report a rare complication related to the insertion of Kirschner wires for stabilization of an acromioclavicular separation. Five years after placement of the Kirschner wires, the patient presented with hemoptysis. On review of chest radiographs, a fractured wire was found to have migrated from the acromioclavicular joint, through the hemithorax and into the trachea.

Acromioclavicular Joint↗

PubMed2001

Respiratory alkalosis.

Respiratory alkalosis is an extremely common and complicated problem affecting virtually every organ system in the body. This article reviews the various facets of this interesting problem. Respiratory alkalosis produces multiple metabolic abnormalities, from changes in potassium, phosphate, and calcium, to the development of a mild lactic acidosis. Renal handling of the above ions is also affected. The etiologies may be related to pulmonary or extrapulmonary disorders. Hyperventilation syndrome is a common etiology of respiratory alkalosis in the emergency department setting and is a diagnosis by exclusion. There are many cardiac effects of respiratory alkalosis, such as tachycardia, ventricular and atrial arrhythmias, and ischemic and nonischemic chest pain. In the lungs, vasodilation occurs, and in the gastrointestinal system there are changes in perfusion, motility, and electrolyte handling. Therapeutically, respiratory alkalosis is used for treatment of elevated intracranial pressure. Correction of a respiratory alkalosis is best performed by correcting the underlying etiology.

Alkalosis, Respiratory↗

PubMed2000

Quantum state reduction and conditional time evolution of wave-particle correlations in cavity QED.

We report measurements in cavity QED of a wave-particle correlation function which records the conditional time evolution of the field of a fraction of a photon. Detection of a photon prepares a state of well-defined phase that evolves back to equilibrium via a damped vacuum Rabi oscillation. We record the regression of the field amplitude. The recorded correlation function is nonclassical and provides an efficiency independent path to the spectrum of squeezing. Nonclassicality is observed even when the intensity fluctuations are classical.

Journal Article↗