Study of transmission line attenuation in broad band millimeter wave frequency range.

Broad band millimeter wave transmission lines are used in fusion plasma diagnostics such as electron cyclotron emission (ECE), electron cyclotron absorption, reflectometry and interferometry systems. In particular, the ECE diagnostic for ITER will require efficient transmission over an ultra wide band, 100 to 1000 GHz. A circular corrugated waveguide transmission line is a prospective candidate to transmit such wide band with low attenuation. To evaluate this system, experiments of transmission line attenuation were performed and compared with theoretical loss calculations. A millimeter wave Michelson interferometer and a liquid nitrogen black body source are used to perform all the experiments. Atmospheric water vapor lines and continuum absorption within this band are reported. Ohmic attenuation in corrugated waveguide is very low; however, there is Bragg scattering and higher order mode conversion that can cause significant attenuation in this transmission line. The attenuation due to miter bends, gaps, joints, and curvature are estimated. The measured attenuation of 15 m length with seven miter bends and eighteen joints is 1 dB at low frequency (300 GHz) and 10 dB at high frequency (900 GHz), respectively.

Confinement of plasma along shaped open magnetic fields from the centrifugal force of supersonic plasma rotation.

Interferometric density measurements in plasmas rotating in shaped, open magnetic fields demonstrate strong confinement of plasma parallel to the magnetic field, with density drops of more than a factor of 10. Taken together with spectroscopic measurements of supersonic E × B rotation of sonic Mach 2, these measurements are in agreement with ideal MHD theory which predicts large parallel pressure drops balanced by centrifugal forces in supersonically rotating plasmas.

Evaluation of a pharmacy-managed warfarin-monitoring service to coordinate inpatient and outpatient therapy.

The effects of implementing a warfarin-monitoring service for inpatients were evaluated. The pharmacy-managed service includes chart review, laboratory interpretation, recommendations for warfarin dosage adjustments, physician and patient education, and coordination of follow-up in the outpatient anticoagulation clinic. In a before-after trial, 52 patients monitored by the warfarin-monitoring service were compared with 97 patients who received warfarin before the service was implemented. Significantly fewer determinations of prothrombin time (PT) and partial thromboplastin time (PTT) were ordered for after-trial patients compared with before-trial patients. PT stability at hospital discharge was significantly improved in after-trial patients. After-trial patients were 12.2 times more likely to be referred to the anticoagulation clinic. No difference was found between the before and after groups in overall compliance with follow-up; however, among patients with no history of substance abuse, after-trial patients were 6.7 times more likely to be compliant. The warfarin-monitoring service had no significant effect on the number of hospital visits and readmissions related to toxicity and recurrence of thrombosis. After-trial patients were 5.4 times more likely to have a therapeutic PT at the initial follow-up appointment. The warfarin-monitoring service improved warfarin dose determination, improved PT stability, and increased referrals to the anticoagulation clinic; among patients with no history of substance abuse, it also improved clinic compliance.

Inhaled albuterol and oral prednisone therapy in hospitalized adult asthmatics. Does aminophylline add any benefit?

STUDY OBJECTIVE: To determine the efficacy of intravenous aminophylline in the treatment of adult patients hospitalized for exacerbation of asthma. DESIGN: Randomized, double-blind, placebo-controlled trial throughout the study. SETTING: University Hospital Clinical Research Center. PATIENTS: Forty-four patients admitted from the emergency room with a primary diagnosis asthma; 39 patients completed the study. INTERVENTIONS: Patients received either intravenous aminophylline or placebo in addition to frequent nebulized albuterol; prednisone 0.5 mg/kg body weight every 6 h orally; and supplemental oxygen. Aminophylline infusion rates were adjusted to achieve serum theophylline concentrations of 10 to 20 micrograms/ml. Changes were made in placebo infusion rates to maintain the double blind design. MEASUREMENTS AND RESULTS: Forced expiratory volume in 1 s (FEV1) and other spirometric measurements every 8 h by a blinded investigator or trained respiratory therapist. Subjective patient response and duration of hospitalization were compared. No difference in spirometric measurements was observed between the two groups at any time point. On admission to the study, FEV1 in the placebo group was 41.5 (+/- 2.9) percent predicted and in the aminophylline group 34.7 (+/- 2.3) percent predicted (p = 0.08). At discharge, FEV1 was 70.4 (+/- 2.9) percent predicted in the placebo group and 63.7 (+/- 2.8) percent predicted in the theophylline group (p = 0.10). There was no difference in subjective patient rating or duration of hospitalization between the two groups (placebo 1.95 days and aminophylline 1.78 days, p = 0.51). CONCLUSIONS: Our results suggest that aminophylline therapy does not add significant benefit to other standard therapies in hospitalized adult asthmatic patients. Because of the risks and cost of aminophylline treatment in the hospital setting, further research is needed to determine if there are subgroups of adult asthmatics who may benefit from the addition of aminophylline to other standard optimal therapies.

Is theophylline use justified in acute exacerbations of asthma?

Despite widespread use of theophylline in the hospital management of asthma, supportive data justifying its use are sparse. Clinical research in the 1980s has forced a serious new examination of the drug's role in acute exacerbations of asthma. Because of the morbidity, mortality, questionable value, and overall cost of theophylline therapy, this reevaluation is of particular importance. Enhanced knowledge of the value of treatment with intensive inhaled beta agonists, systemic glucocorticoids, and inhaled ipratropium should prompt elimination of the routine, initial use of theophylline in emergency room care of most asthmatics. Further research is necessary to justify the routine, initial use of the drug in hospitalized asthmatics.

Early use of oral theophylline in hospitalized chronic obstructive pulmonary disease patients: cost-containment through medical education.

This study measured the impact of an education program conducted by a clinical pharmacist on early conversion from intravenous to oral theophylline in hospitalized chronic obstructive pulmonary disease patients. Two separate two-month audit periods were conducted on the pulmonary medicine service (PMS) of a teaching hospital. During the first audit period (pre-ed), no education was provided. Prior to each month of the second two-month audit period (post-ed), an education program and handout outlining the rationale for early conversion from intravenous to oral theophylline was presented to medicine residents rotating onto the PMS. The results of this preliminary study suggest that the education program was responsible for a statistically significant decrease in intravenous aminophylline therapy from three days (pre-ed) to one day (post-ed). As a result of the reduction in length of intravenous therapy, both drug costs and patient charges were reduced by a statistically significant amount.

The Northwestern University Multihospital Twin Study. II. Mortality of first versus second twins.

The results of a multihospital study involving a total of 588 twin pairs born in Chicago in 1970-1975 are reported, with special respect to differences in mortality between first and second twins by time as well as by cause of death. Mortality was higher in second than in first twins and most commonly occurred after delivery and was the result of immaturity and of respiratory distress syndrome.