Planar-dielectric-wakefield accelerator structure using Bragg-reflector boundaries.

We report experimental measurements of narrow-band, single-mode excitation, and drive beam energy modulation, in a dielectric wakefield accelerating structure with planar geometry and Bragg-reflector boundaries. A short, relativistic electron beam (∼1 ps) with moderate charge (∼100 pC) is used to drive the wakefields in the structure. The fundamental mode of the structure is reinforced by constructive interference in the alternating dielectric layers at the boundary, and is characterized by the spectral analysis of the emitted coherent Cherenkov radiation signal. Data analysis shows a narrow-band peak at 210 GHz corresponding to the fundamental mode of the structure. Simulations in both 2D and 3D provide insight into the propagating fields and reproduction of the electron beams dynamics observables and emitted radiation characteristics.

Generation and characterization of electron bunches with ramped current profiles in a dual-frequency superconducting linear accelerator.

We report on the successful experimental generation of electron bunches with ramped current profiles. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a superconducing radio frequency linear accelerator operating at two frequencies and a current-enhancing dispersive section. The produced ~700-MeV bunches have peak currents of the order of a kilo-Ampère. Data taken for various accelerator settings demonstrate the versatility of the method and, in particular, its ability to produce current profiles that have a quasilinear dependency on the longitudinal (temporal) coordinate. The measured bunch parameters are shown, via numerical simulations, to produce gigavolt-per-meter peak accelerating electric fields with transformer ratios larger than 2 in dielectric-lined waveguides.

Continually improving the health and value of health care for a population of patients: the panel management process.

Today's primary care provider faces the challenge of caring for individual patients as well as caring for populations of patients. This article offers a model--the panel management process--for understanding and managing these activities and relationships. The model integrates some of the lessons learned during the past decade as we have worked to gain an understanding of the continual improvement of health care after we have understood that care as a process and system.

Fostering the leadership of a continually improving healthcare organization.

Governing board members and other healthcare leaders naturally want to see their organizations improve, but they often have difficulty connecting leadership functions to daily work in the organization in order to produce improvement. This article offers a framework, including a series of self-assessment questions, to help leaders foster continual improvement within their organization. Such improvement becomes possible when people join professional knowledge with a new body of knowledge called improvement knowledge. Continual improvement results when leaders enable everyone in the organization to build new knowledge, to test changes in daily work, and to learn from these tests. Essential to building and applying knowledge in this way are a leadership policy that fosters a shared sense of purpose and promotes learning, tools and methods that accelerate the development of new knowledge and improvement, and systematic strategies for building and applying that new knowledge to the process of daily work, and to the functions of leadership itself.

A framework for the continual improvement of health care: building and applying professional and improvement knowledge to test changes in daily work.

We seem to lack a well-defined, comprehensive, and shared understanding of what is required for the continual improvement of health care--at the organizational and the industry levels. This article presents a framework that defines the new body of knowledge which, when joined with the professional knowledge of health care workers, can make continual improvement possible; and gives requirements for building and applying this knowledge to bring about improvement in health care organizations.