John E. Barnes

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Xenon computerized tomography (Xe CT) blood flow studies were conducted in 25 patients referred for a possible extracranial-intracranial bypass procedure for occlusive vascular disease in one or more extra- or intracranial vessels. These studies were helpful in selecting eight candidates for surgery. The Xe CT studies were performed at one or two brain(More)
The pattern of photosynthetic carbon metabolism was determined in tissue cultures of Portulaca oleracea. Four-carbon acids are the most heavily labeled photosynthetic products during short term exposure to (14)CO(2), containing greater than 40% of the total radioactivity incorporated. Phosphoglyceric acid and sugars account for only 10% of the label after(More)
Ionization chambers often exhibit a stem effect, caused by interactions of radiation with air near the chamber end, or with dielectric in the chamber stem or cable. These interactions contribute to the apparent measured exposure. To determine the stem efffect for several common ionization chamber systems, exposures were measured with TLD capsules placed at(More)
We have developed a Fabry-Perot interferometer and image-plane detector system to be used as a receiver for a Doppler lidar. This system incorporates the latest technology in multichannel detectors, and it is an important step toward the development of operational wind profiler systems for the atmosphere (troposphere, stratosphere, and lower mesosphere).(More)
Computed tomography (CT) using metrizamide is a valuable tool in the neuroradiologic evaluation of the spinal cord, but CT must be used with care when measuring object size because size may vary with different window center (level) settings. A simple method to determine appropriate window center (level) settings during CT object measurement is described. A(More)
—The Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit/Humidity Sounder for Brazil (AIRS/AMSU/HSB) instrument suite onboard Aqua observes infrared and microwave radiances twice daily over most of the planet. AIRS offers unprecedented radiometric accuracy and signal to noise throughout the thermal infrared. Observations from the combined suite of(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Abstract Understanding the cooling effect of recent volcanoes is of(More)