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Biomedical subjects

M Borland

Publications and source records attributed to M Borland.

9 recordsLinked to original sources
PubMed2002

Evidence for microbunching "sidebands" in a saturated free-electron laser using coherent optical transition radiation.

We report the first measurements of z-dependent coherent optical transition radiation (COTR) due to electron-beam microbunching at high gains ( >10(4)) including saturation of a self-amplified spontaneous emission free-electron laser (FEL). In these experiments the fundamental wavelength was near 530 nm, and the COTR spectra exhibit the transition from simple spectra to complex spectra ( 5% spectral width) after saturation. The COTR intensity growth and angular distribution data are reported as well as the evidence for transverse spectral dependencies and an "effective" core of the beam being involved in microbunching.

Journal Article↗
PubMed2001

Exponential gain and saturation of a self-amplified spontaneous emission free-electron laser.

Self-amplified spontaneous emission in a free-electron laser has been proposed for the generation of very high brightness coherent x-rays. This process involves passing a high-energy, high-charge, short-pulse, low-energy-spread, and low-emittance electron beam through the periodic magnetic field of a long series of high-quality undulator magnets. The radiation produced grows exponentially in intensity until it reaches a saturation point. We report on the demonstration of self-amplified spontaneous emission gain, exponential growth, and saturation at visible (530 nanometers) and ultraviolet (385 nanometers) wavelengths. Good agreement between theory and simulation indicates that scaling to much shorter wavelengths may be possible. These results confirm the physics behind the self-amplified spontaneous emission process and forward the development of an operational x-ray free-electron laser.

Journal Article↗
PubMed2001

First Observation of z-Dependent Electron-Beam Microbunching Using Coherent Transition Radiation.

We report the first measurements of the electron-beam microbunching z dependence in a self-amplified spontaneous-emission (SASE) free-electron laser (FEL) experiment by the observation of visible wavelength coherent transition radiation (CTR). In this case the fundamental SASE wavelength was at 537 nm, and the CTR exhibited an exponential intensity growth similar to the SASE radiation. In addition, we observed for the first time structure in the CTR angular distribution patterns that may be useful for optimizing SASE FEL performance.

Journal Article↗
PubMed2000

Observation of self-amplified spontaneous emission and exponential growth at 530 nm

Experimental evidence for self-amplified spontaneous emission (SASE) at 530 nm is reported. The measurements were made at the low-energy undulator test line facility at the Advanced Photon Source, Argonne National Laboratory. The experimental setup and details of the experimental results are presented, as well as preliminary analysis. This experiment extends to shorter wavelengths the operational knowledge of a linac-based SASE free-electron laser and explicitly shows the predicted exponential growth in intensity of the optical pulse as a function of length along the undulator.

Journal Article↗
PubMed1994

A community quality initiative for health care reform.

In 1989, the Madison Area Employers Health Care Coalition conducted a feasibility study for the purpose of finding solutions to common health care concerns. The study revealed three conclusions: (1) there was little or no price competition among providers; (2) employers lacked useful data and information regarding health care costs and outcomes; and (3) employers and employees lacked basic health care consumerism. These conclusions led to the development of a health care purchasing group in the spring of 1990 with the formation of the Employers Health Care Alliance Cooperative (The Alliance). The conclusions outlined above became the cornerstone of the services offered by The Alliance, which include provider contracting, data collection, and consumer education and advocacy. The Alliance also developed the community quality initiative, a partnership of employers, health care consumers, and providers committed to using continuous quality improvement methods.

Community Health Services↗
PubMed1990

Vaginal cones for the treatment of genuine stress incontinence.

The value of vaginal cones for genuine stress incontinence was assessed in 34 women with this condition. Subjective and objective assessments were made before and after 6 weeks of treatment using urinary diaries, perineometry, 'home' pad test and cone weights with and without voluntary pelvic floor contraction. There was a subjective improvement in 23 of the 34 women (68%) after 6 weeks of cone use with 16 (47%) deciding that no additional treatment other than cone therapy was required at this time. Statistical analyses showed that there were significant improvements in the objective indices. There were no side-effects observed with cone use. When followed up 12-24 (mean 15.8) months from the start of the study, 14 women (41%) were still improved with either cone or pelvic floor exercises. Vaginal cones would seem to be a simple and practical means of improving both pelvic floor strength and genuine stress incontinence.

Adult↗
PubMed1987

Application of a frequency definition of ventricular proarrhythmia.

To differentiate spontaneous variability from proarrhythmia in patients with benign or potentially lethal ventricular arrhythmias, 495 patients with 2 or more Holter tracings during placebo therapy were evaluated. The Holter session with the highest frequency of ventricular premature complexes (VPCs) and ventricular tachycardia was compared with the first placebo recording. Patients were segregated by their baseline frequency of VPCs. The percent of patients taking placebo in this trial who had the same increase in VPC frequency as has been ascribed to those with proarrhythmia varied from 0 of 470 patients with a baseline frequency of ventricular arrhythmia of 10 to 50 VPCs/hour, 3 of 44 (7%) with 51 to 100 VPCs/hour, 1 of 139 (0.7%) with 101 to 300 VPCs/hour and 1 of 265 (0.04%) with more than 300 VPCs/hour. Overall, 5 of 496 (1%) patients would have been classified as having proarrhythmia using the algorithm although only placebo was given. A 10-fold or greater increase in ventricular tachycardia beats in patients taking placebo occurred in 9 of 274 patients (3%). Thus, a simple algorithm to define proarrhythmia in patients with mixed cardiac disease and chronic ventricular arrhythmias can be defined and differentiated from spontaneous variability. This arbitrary algorithm defines proarrhythmia as an increase of more than 3 times when baseline VPC frequency is more than 100 VPCs/hour and more than 10 times when that frequency is less than 100 VPCs/hour with a false-positive rate of only 1%.

Algorithms↗