Materials processing using radio-frequency ion-sources: Ion-beam sputter-deposition and surface treatment.

The capabilities of ion-beam techniques for thin-film processing, i.e., for materials deposition by ion-beam sputtering and surface treatment, are reviewed. The basic interaction mechanisms between ions and solids are summarized and related to materials processing by ion sources. Typical geometries of ion sources, targets, and samples are discussed for corresponding experimental apparatus. The versatility of ion-beam techniques in the preparation of thin films and multilayer structures is illustrated by several examples: ion-beam sputter-deposition of various binary oxide materials (including crystalline MgO, NiO, ZnO, SnxOy, and CuxOy) as well as combinatorial growth of materials libraries of amorphous ternary oxides. Furthermore, controlled ion-beam etching of surfaces is discussed.

Absorption characteristics of EC-MPS--an enteric-coated formulation of mycophenolic sodium.

UNLABELLED: Enteric-coated mycophenolate sodium is an advanced formulation delivering mycophenolic acid (MPA), designed to improve MPA-related upper gastrointestinal adverse events by delaying MPA release until the small intestine. OBJECTIVE: Two studies were undertaken to identify the absolute bioavailability and dose-proportionality of enteric-coated mycophenolate sodium in stable renal transplant patients receiving cyclosporine. METHODS: Study 1: The mean MPA AUC(0-t) was shown to be greater after MPA infusion than after oral enteric-coated mycophenolate sodium (42.1 vs. 28.9 microg x h/ml). Mean absolute bioavailability was 0.71 +/- 0.21 (SD). Study 2: The AUC(0-t) and C(max) for MPA were proportional to the dose of enteric-coated mycophenolate sodium, similarly mean AUC(0-infinity) and C(max) for MPA glucuronide were proportional to dose administered. RESULTS AND CONCLUSIONS: In patients receiving cyclosporine the absolute bioavailability of MPA provided by enteric-coated mycophenolate sodium is equivalent to that provided by mycophenolate mofetil when administered in combination with cyclosporine, and exhibits dose-proportionality. Enteric-coated mycophenolate sodium was well tolerated from 180 - 2,160 mg with no serious adverse events reported.

Creating a peaceful school learning environment: a controlled study of an elementary school intervention to reduce violence.

OBJECTIVE: The impact of a manual-based antiviolence program on the learning climate in an elementary school over 4 years was compared with the outcome in a control school. METHOD: The two schools were matched for demographic characteristics. The intervention in the experimental school was based on zero tolerance for bullying; the control school received only regular psychiatric consultation. Disciplinary and academic achievement data were collected in both schools. RESULTS: The experimental school showed significant reductions in discipline referrals and increases in scores on standardized academic achievement measures. CONCLUSIONS: A low-cost antiviolence intervention that does not focus on individual pathology or interfere with the educational process may improve the learning environment in elementary schools.

Dose reduction in CT by anatomically adapted tube current modulation. I. Simulation studies.

Tube current modulation governed by x-ray attenuation during CT (computed tomography) acquisition can lead to noise reduction which in turn can be used to achieve patient dose reduction without loss in image quality. The potential of this technique was investigated in simulation studies calculating both noise amplitude levels and noise distribution in CT images. The dependence of noise on the inodulation function, amplitude of modulation, shape and size of the object, and possible phase shift between attenuation and modulation function were examined. Both sinusoidal and attenuation-based control functions were used to modulate tube current. Noise reduction was calculated for both ideal systems and for real systems with limited modulation amplitude. Dose reductions up to 50% can be achieved depending on the phantom geometry and tube current modulation function. Attenuation-based tube current modulation yields substantially higher reduction than fixed-shape modulation functions. Optimal results are obtained when the current is modulated as a function of the square root of attenuation. A modulation amplitude of at least 90% should be available to exploit the potential of these techniques.

Dose reduction in CT by on-line tube current control: principles and validation on phantoms and cadavers.

We investigated approaches to reducing the dose in CT without impairing image quality. Dose can be reduced for non-circular object cross-sections without a significant increase in noise if X-ray tube current is reduced at angular tube positions where the X-ray attenuation by the patients is small. We investigated different schemes of current modulation during tube rotation by simulation and phantom measurements. Both pre-programmed sinusoidal modulation functions and attenuation-based on-line control of the tube current were evaluated. All relevant scan parameters were varied, including constraints such as the maximum modulation amplitude. A circular, an elliptical and two oval water phantoms were used. Results were validated on six cadavers. Dose reduction of 10-45% was obtained both in simulations and in measurements for the different non-circular phantom geometries and current modulation algorithms without an increase in pixel noise values. On-line attenuation-based control yielded higher reductions than modulation by a sinusoidal curve. The maximal dose reduction predicted any simulations could not be achieved due to limits in the modulation amplitude. In cadaver studies, a reduction of typically 20-40% was achieved for the body and about 10% for the head. Variations of our technique are possible; a slight increase in nominal tube current for high-attenuation projections combined with attenuation-based current modulation still yields significant dose reduction, but also a reduction in the structured noise that may obscure diagnostic details. We conclude that a significant reduction in dose can be achieved by tube current modulation without compromising image quality. Attenuation-based on-line control and a modulation amplitude of at least 90% should be employed.

A trial of structured implicit review of randomly selected peer review organization cases.

OBJECTIVE: In order to learn more about peer review's acceptability, efficiency, and reliability, we performed structured implicit review with and without use of a structured case review form on a random selection of peer review organization cases. METHODS: We compared the results between methods and with previously obtained review results. Twenty-five charts with physician review completed during the Health Care Financing Administration's Third Scope of Work were randomly selected for rereview. Eight physician advisors, none of whom had seen any of these charts previously, were divided into two groups. Both groups received identical formal instruction in the structured implicit review method. Half of the physicians used a structured review form when performing chart review. The other half did not use this form but completed their reviews using the previously used reporting form. Participating physicians were instructed in the structured review method as described by Rand Corporation. The review process was examined regarding acceptability and efficiency. Review results were analyzed for reliability regarding identification of adverse and potential adverse effects and identification of the source of quality concerns. RESULTS: Instructions regarding structured implicit review methods were understood easily and accepted by physician advisors. Use of the structured review form was less efficient, averaging 50% longer per review. There was no difference in the rate at which adverse events were detected. Potentially serious adverse events were found less often using structured review than in the original review. There was greater agreement among reviewers using the structured form than among those using the historic worksheet, but structured review using the Rand form identified fewer potentially significant adverse events than did the reviewers using the historic worksheets. CONCLUSIONS: Application of structured implicit review methods is clearly feasible for peer review organization case review. Use of a simple worksheet was more time efficient than use of a highly structured form. There was not only less variation in review results but also identification of fewer potentially significant adverse events when the highly structured form was used. Teaching the structured approach to chart review may be more important to obtaining good results than using a structured review form.