Large-scale complementary integrated circuits based on organic transistors

Thin-film transistors based on molecular and polymeric organic materials have been proposed for a number of applications, such as displays and radio-frequency identification tags. The main factors motivating investigations of organic transistors are their lower cost and simpler packaging, relative to conventional inorganic electronics, and their compatibility with flexible substrates. In most digital circuitry, minimal power dissipation and stability of performance against transistor parameter variations are crucial. In silicon-based microelectronics, these are achieved through the use of complementary logic-which incorporates both p- and n-type transistors-and it is therefore reasonable to suppose that adoption of such an approach with organic semiconductors will similarly result in reduced power dissipation, improved noise margins and greater operational stability. Complementary inverters and ring oscillators have already been reported. Here we show that such an approach can realize much larger scales of integration (in the present case, up to 864 transistors per circuit) and operation speeds of approximately 1 kHz in clocked sequential complementary circuits.

Validation of professional licensure examinations. Professions theory, test design, and construct validity.

Although the unitary view of test validity has gained support recently, it has real limitations where professional licensing examinations are concerned. A strategy for validation of professional licensure tests requires modifying conventional approaches in three ways. First, a theory of professions must be incorporated into the test development process so as to acknowledge the social character of professions. Second, the importance of test design in the validation of licensing tests should be enhanced. Third, the concept of construct validation must be expanded to accommodate the special features of content that inhere to professional licensure testing. Methods for accomplishing these three things are described and the implications of these and other views discussed.

Item modelling procedure for constructing content-equivalent multiple choice questions.

Recent research on multiple choice questions has identified deficiencies of inadequate content-equivalence and item-writer bias. Systematic methods of writing multiple choice questions are being advocated as effective responses. This article describes preliminary development of a new item-writing method. Details of the procedure, called item modelling, are provided.

The design of a new physician licensure examination.

Many health professions include written examinations among their licensing procedures, and constructing these examinations poses special difficulties. For physician licensure the central dilemma is manifested by the longstanding tradition of undifferentiated licensure contrasting with the strong specialty orientation of contemporary physician training. This article details the authors' response to this problem and describes the resulting design of a new physician licensure examination. Using a combination of empirical data and expert judgment, descriptions of selected clinical encounters have been assembled as a practice model of a physician licensed for the delivery of general health care of patients. Application of an explicitly situational framework to the design of a physician licensure examination is unusual, and the approach is advocated for use with other health professions.

The structure of competence in health professions.

The past decade has seen widespread research on systematic evaluation of the competence of health professionals. Such activity usually has been carried out in accordance with the prevailing psychological paradigms, in which competence is represented as a trait, or as an intrapsychic factor. However, even when competence has been delimited as problem-solving, the research generally identified a strong situational influence on performance. In this article are assembled a set of diverse but complementary arguments for dispensing with the conventional representations of professional competence. In their place is proposed a relational model in which competence in health professions is seen as the aggregated adaptations of practitioners to the set of special social circumstances that obtain within the situational boundaries of their profession. It is argued that a thorough understanding of the content of professional situations is a necessary prerequisite for successful evaluation of professional competence, since competent behavior is lodged in a network of probabilistic relationships with the surroundings. Also discussed are selected procedural implications of this new model for the conduct of investigations of professional situations.

Criterion-referenced testing in medical technology education: Professional Performance Situation Model.

In applying the Professional Performance Situation Model to the medical technology profession, situations describing actual laboratory performance are used as a basis for defining competence. As these definitions of competence are derived, appropriate criterion-referenced (domain-referenced) assessments are designed to measure the achievement of competence. This paper describes the process by which situations representing clinical practice are derived, the extrapolation of skill and knowledge statements reflecting expected performance, the generation of domains of competence, the design of criterion-referenced assessments, and some examples of prototype instruments used to assess attainment of the competence. The techniques include multiple choice items, checklists for use in the clinical component of the educational experience, and the adaptation of the written simulation for instruction and evaluation in medical laboratory sciences education. Validity of this approach is discussed, as well as possible implications for its use in developing assessments to measure continued competence in the profession beyond the baccalaureate education.

Progress toward development of a general model for competence definition in health professions.

For the past three years a team of educational evaluators and health professionals has worked on development of (1) definitions of competence in occupational therapy, clinical dietetics and medical technology, and (2) associated prototype assessment instruments. This study has also involved an effort to develop a research methodology for pursuing similar investigations in other fields. That methodology, the Professional Performance Situation Model, proved appropriate for occupational therapy. A second application with clinical dietetics brough a number of significant modifications which support the view that PPSM is a valid special model for direct patient contact health professions. The third application, with medical technology, is intended to extend PPSM as a general model for competence definition in health professions. This article concentrates on the application of PPSM in clinical dietetics. It is argued that evidence for the feasibility and validity of PPSM is sufficient to justify confidence in the methodology. Completion of the next phase of development promises to support the authors' contention that they have developed a general paradigm for competence definition and assessment in all health professions.