University of Iowa

About: University of Iowa is a education organization based out in Iowa City, Iowa, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 49229 authors who have published 109171 publications receiving 5021465 citations. The organization is also known as: UI & The University of Iowa.

Task Group 142 report: quality assurance of medical accelerators.

Abstract: The task group (TG) for quality assurance of medical accelerators was constituted by the American Association of Physicists in Medicine's Science Council under the direction of the Radiation Therapy Committee and the Quality Assurance and Outcome Improvement Subcommittee. The task group (TG-142) had two main charges. First to update, as needed, recommendations of Table II of the AAPM TG-40 report on quality assurance and second, to add recommendations for asymmetric jaws, multileaf collimation (MLC), and dynamic/virtual wedges. The TG accomplished the update to TG-40, specifying new test and tolerances, and has added recommendations for not only the new ancillary delivery technologies but also for imaging devices that are part of the linear accelerator. The imaging devices include x-ray imaging, photon portal imaging, and cone-beam CT. The TG report was designed to account for the types of treatments delivered with the particular machine. For example, machines that are used for radiosurgery treatments or intensity-modulated radiotherapy (IMRT) require different tests and/or tolerances. There are specific recommendations for MLC quality assurance for machines performing IMRT. The report also gives recommendations as to action levels for the physicists to implement particular actions, whether they are inspection, scheduled action, or immediate and corrective action. The report is geared to be flexible for the physicist to customize the QA program depending on clinical utility. There are specific tables according to daily, monthly, and annual reviews, along with unique tables for wedge systems, MLC, and imaging checks. The report also gives specific recommendations regarding setup of a QA program by the physicist in regards to building a QA team, establishing procedures, training of personnel, documentation, and end-to-end system checks. The tabulated items of this report have been considerably expanded as compared with the original TG-40 report and the recommended tolerances accommodate differences in the intended use of the machine functionality (non-IMRT, IMRT, and stereotactic delivery).

What teachers say and do to support students' autonomy during a learning activity.

Abstract: Teachers with an autonomy-supportive style rely on different instructional behaviors to motivate their students than do teachers with a controlling style. In the present investigation, the authors tested which of these instructional behaviors actually correlated positively or negatively with students' autonomy. The authors used Deci, Spiegel, Ryan, Koestner, & Kauffman's (1982) teacher-student laboratory paradigm to randomly assign 72 pairs of same-sex preservice teachers into the role of either teacher or student. From videotapes of the 10-min instructional episode, raters scored 11 hypothesized autonomy-supportive behaviors and 10 hypothesized controlling behaviors. Correlational analyses confirmed that students perceived the functional significance of 8 instructional behaviors as autonomy supports and 6 instructional behaviors as autonomy thwarts. The discussion focuses on the interpretation and classroom implications of these data.

Growth, beta and agency costs as determinants of dividend payout ratios

Abstract: A model of optimal dividend payout is presented in which increased dividends lower agency costs but raise the transactions cost of external financing. The optimal dividend payout minimizes the sum of these two costs. A cross-sectional test of the model relates dividend payout to the fraction of equity held by insiders, the past and expected future revenue growth of the firm, the firm's beta coefficient, and the number of common stockholders. The coefficients of all variables are significant in the predicted directions. The results indicate that investment policy influences dividend policy.

Bilateral Deep Brain Stimulation vs Best Medical Therapy for Patients With Advanced Parkinson Disease: A Randomized Controlled Trial

Abstract: Context Deep brain stimulation is an accepted treatment for advanced Parkinson disease (PD), although there are few randomized trials comparing treatments, and most studies exclude older patients. Objective To compare 6-month outcomes for patients with PD who received deep brain stimulation or best medical therapy. Design, Setting, and Patients Randomized controlled trial of patients who received either deep brain stimulation or best medical therapy, stratified by study site and patient age ( Intervention Bilateral deep brain stimulation of the subthalamic nucleus (n = 60) or globus pallidus (n = 61). Patients receiving best medical therapy (n = 134) were actively managed by movement disorder neurologists. Main Outcome Measures The primary outcome was time spent in the “on” state (good motor control with unimpeded motor function) without troubling dyskinesia, using motor diaries. Other outcomes included motor function, quality of life, neurocognitive function, and adverse events. Results Patients who received deep brain stimulation gained a mean of 4.6 h/d of on time without troubling dyskinesia compared with 0 h/d for patients who received best medical therapy (between group mean difference, 4.5 h/d [95% CI, 3.7-5.4 h/d]; P Conclusion In this randomized controlled trial of patients with advanced PD, deep brain stimulation was more effective than best medical therapy in improving on time without troubling dyskinesias, motor function, and quality of life at 6 months, but was associated with an increased risk of serious adverse events. Trial Registration clinicaltrials.gov Identifier: NCT00056563