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Biomedical subjects

J B Willis

Publications and source records attributed to J B Willis.

16 recordsLinked to original sources
PubMed1994

Synaptic integration of NMDA and non-NMDA receptors in large neuronal network models solved by means of differential equations.

Alpha functions are commonly used to describe different receptor channel kinetics (non-NMDA, GABAA and GABAB). In this paper we show that they may be represented as solutions to simple ordinary differential equations. This alternative method is compared with the commonly used direct summation of the alpha function conductances in a high-level neuronal circuit model. A parametric study shows that the differential equation method greatly speeds up the previous summation method. The forward Euler method used to solve this differential equation is shown to be accurate for this type of simulation. The modelling of NMDA receptor channel kinetics is also discussed.

Animals↗
PubMed1993

Underutilization of physician assistants in physical medicine and rehabilitation.

This study was undertaken to determine the utilization of physician assistants (PAs) in physical medicine and rehabilitation (PM&R). Survey questionnaires were sent to members of the American Academy of Physical Medicine and Rehabilitation, members of the American Academy of Physician Assistants, and administrators of free-standing rehabilitation facilities. One hundred thirty-seven of 1,082 physiatrists (13% of those responding) reported PAs employed in their practice settings, 83 of 549 PAs (15% of those responding) identified PM&R as their specialty, and 17 of 65 hospital administrators, (27% of those responding) reported PAs working at their facility. Seventy-nine percent (713 of 903) of physicians and 77% (50 of 65) of administrators were unaware that PA services provided in inpatient settings are reimbursed by Medicare. Eighty-four percent (108 of 129) of physiatrists employing PAs indicated that they would continue to do so even if the supply of physiatrists were adequate. PA responsibilities were concentrated in inpatient clinical areas. It is concluded that PAs are an underutilized source of health care for rehabilitation patients. Increased professional visibility and formal specialty training are recommended to enhance their contribution to the field.

Adult↗
PubMed1993

Simulation of epileptiform activity in the hippocampus using transputers.

Transputer technology is exploited to provide fast and interactive simulations of the electrical behaviour in large networks of neurones derived from experimental data of individual neurones and their connections. A synchronous numerical integration routine and an efficient communication scheme have been developed to run on toroidally configured transputer arrays of any sizes. A population of neurones up to 6400 from the hippocampus has been simulated on 19 Inmos T800 transputers. The activity of individual cells has been modelled using a similar approach to that of Traub; but the non-linear dynamics of the Na(+)-K+ channels is emphasised to explain intrinsic bursting. This model includes a description of the cellular channel currents INa, IK(DR), IK(C), ICa and IAHP. Preliminary studies indicate that this anatomically based model can be used to study the dynamic properties of neurones in the hippocampus, including monitoring the behaviour of subpopulation of cells that contribute to epileptiform activity.

Animals↗
PubMed1986

The future of Medicare policy reform: priorities for research and demonstrations.

The Medicare program, the largest health insurance program in the United States, is clearly at a crossroads as it enters its third decade. Historical increases in health care expenditures, plus a changing political and economic landscape, have set the groundwork for policy reform. Basic reform strategies, most notably reimbursement arrangements, are discussed. In 1983, Congress enacted the prospective payment system (PPS), which initiated a fundamental change in the way hospitals are paid for care delivered to Medicare beneficiaries. But PPS is only a steppingstone to broader reforms such as capitation and evolving organizational models in the delivery of care. Policymakers' considerations of coverage of services, such as long-term care and organ transplants, are also discussed. Within the context of these policy reforms, the authors shape an agenda for research and demonstrations--the blueprint for taking us from "here to there."

Health Services Research↗
PubMed1986

1985 physician assistant role delineation study: ten years later.

A major task of the American Academy of Physician Assistants has been to safeguard the PA's place in today's health care system. Given continued growth of the profession and the diversity of PA employment in specialty settings, periodic review of PA role delineation has been mandatory. To date, three such studies have been conducted: by the National Board of Medical Examiners in 1971 and by the AAPA in 1976 and 1985. This Special Article highlights data collected on practice specialty and performance of individual tasks from the 1985 study. The results show that regardless of practice specialty, PAs are responsible for a broad range of primary care tasks; most primary care tasks performed are fundamental and common to all PAs; and a significant difference exists among specialties, particularly responsibility level and the frequency of performing a specific task. The data do not address ability or expertise in performing those tasks.

Data Collection↗
PubMed1985

Resident tracking health information system. Inpatient setting.

The tracking of residents' patient care activities in the hospital setting is valuable to the residency program directors for consideration of curricular changes and to the resident for documentation of experience. Furthermore, the cost-effective method of using patient data generated by hospital billing systems eliminates the need for double entry and assures a high degree of accuracy. This article discusses the use of a computerized tracking system, providing examples of data displays and interpretations.

Area Health Education Centers↗
PubMed1983

A preliminary analysis of accreditation criteria for surgical procedures by orthopedic residents.

The study reported here represented a preliminary evaluation of the accreditation criteria for orthopedic operative procedures. Because selection of the criteria has not been guided by empirical data, the extent to which they accurately reflect resident clinical experience is of concern. To examine this question, residents in an orthopedic residency program were tracked for one year, and their activities were compared with the procedure requirements established by the Residency Review Committee (RRC) for Orthopaedic Surgery. The results indicated that the RRC categories unduly emphasized activities for which there was little patient demand and failed to distinguish or require some frequently performed procedures. In their present form, therefore, the designated categories were not found to cover adequately the content of current clinical practice and thus may not appropriately reflect educational needs.

Accreditation↗
PubMed1980

On the interaction between spinal locomotor generators in quadrupeds.

(1) The spinal locomotor generator of Miller and Scott may be regarded as a circuit of 4 neural 'elements' two of which are composite (i.e. they comprise two neurones). An analysis of all 4-element circuits with inhibitory interconnections reveals only one suitable arrangement. In that sense Miller and Scott's model is unique. (2) A set of simple but non-linear differential equations is proposed to describe the behaviour of 4 interacting populations of elements. The resulting system exhibits stable oscillatory behaviour under suitable conditions. (3) A set of 4 such oscillators, suitably coupled, is proposed as a model for the spinal control of corresponding joint muscles in each of 4 limbs. (4) The resulting system exhibits 4 types of oscillatory behaviour which correspond to the Trot, Pace, Gallop and Bound gaits of quadruped locomotion. (5) Mechanisms are suggested to account for transitions between gaits.

Animals↗