Decision under Uncertainty : the Classical Models

This chapiter of a collective book is dedicated to classical decision models under uncertainty, i.e. under situations where events do not have "objective" probabilities with which the Decision Marker agrees. We present successively the two main theories, their axiomatic, the interpretation and the justification of their axioms and their main properties : first, the general model of Subjective Expected Utility due to Savage (Savage, 1954), second, the Anscombe-Aumann (1963) theory, in a different framework. Both theories enforce the universal use of a probabilistic representation. We then discuss this issue in connection with the experimental result known as the Ellsberg paradox.Uncertainty, subjective probability, Subjective Expected Utility, Savage, Anscombe and Aumann, Ellsberg paradox.

Regular updating

We study the Full Bayesian Updating rule for convex capacities. Following a route suggested by Jaffray (1992), we define some properties one may want to impose on the updating process, and identify the classes of (convex and strictly positive) capacities that satisfy these properties for the Full Bayesian updating rule.

Physical Factors Influencing The Quality Of Megavoltage Radiographs

It has been recognized that improved methods of verifying radiation field placement in external beam radiotherapy are required in order to make frequent checks of field placement feasible. As a result, a large number of electronic portal imaging systems have been developed as possible replacements for film. These developments have produced digital systems with faster acquisition and display (few seconds), but the quality of the images acquired with such systems is still disappointing. The reasons for this are not well known, possibly because relatively few studies of the fundamental physics of imaging at megavoltage energies have been made.;This thesis examines many of the fundamental factors which limit the quality of radiographs obtained with a megavoltage radiotherapy beam. The size and shape of the radiation sources in ten radiotherapy machines were measured using a CT reconstruction technique. A novel technique was also developed to measure the extra-focal source in medical linear accelerators. It was found that the focal spots of modern medical linear accelerators should not influence significantly image quality if reasonable radiographic magnifications (1.2-1.4) are used. The extra-focal source measurements demonstrate that the x-ray source of a medical linear accelerator is composed of two components: a small focal spot surrounded by a large extra-focal component. While the extra-focal source does not influence significantly image quality, it does have important implications for radiotherapy dosimetry. In addition, a detailed Monte Carlo simulation of x-ray interactions within the patient determined that a significant fraction of the x-ray scatter generated in the patient is due to bremsstrahlung and positron annihilation and that the scatter fractions found in megavoltage imaging are lower (0.3-0.5) than those found in diagnostic imaging (0.8-0.9). The impact of the scatter fluence on the contrast and the signal-to-noise characteristics of a therapy image is presented for a variety of therapy imaging detectors. Finally, the interaction of x-rays within typical fluoroscopic imaging detectors (metal plate/phosphor screen) is examined using Monte Carlo techniques. This study shows that failure to include electron transport in determining the quantum absorption efficiency of metal plate/phosphor detectors can lead to gross (factor of 2) inaccuracies. In addition, our study demonstrates that x-ray absorption noise at megavoltage energies can reduce the detective quantum efficiency of these detectors by a factor of 2

Expression of alphaA crystallin: A human lens protein

One of the leading causes of serious visual impairment in young children is congenital cataracts (1). Cataracts and subsequent reductions in vision are the result of opacification of the lens. The human lens is primarily made up of water-soluble proteins called crystallins, which are divided into three groups, alpha, beta, and gamma (2). Mutations in all three of the types have been found to cause the formation of cataracts, although the exact mechanisms remain elusive (3). An autosomal dominant mutation in human alphaA crystallin was discovered to be the cause of one type of congenital cataract in humans (3). In order to study the mechanism by which this mutation results in cataract formation it is necessary to first study the normal form of human alphaA crystallin. This project accomplishes the expression, isolation, and purification of human alphaA crystallin

David Jaffray, PhD, Oral History Interview, July 07, 2021

Interview Chapters Chapter 01: Personal and Educational Background Chapter 02: Navigating a Pandemic Chapter 03: Digital Transformationshttps://openworks.mdanderson.org/mda2020_interviewsessions/1033/thumbnail.jp

Nursing Competencies Needed for Electronic Advance Care Planning in Community

Advance care planning implementation occurs acrossthe world using different legislative frameworks, differentlanguage to describe both the process and the outcome, anddifferent models to develop these plans. Many countries are inthe process of developing personally controlled electronic healthrecords. Including advance care plans as part of this record isproposed in Australia. The Electronic Advance Care Plan(eACP) in Community project aimed to develop a model that willengage community dwelling older adults with chronic lifelimitingillnesses in the process of advance care planning that isperson-centred, evidence-based and has a focus of dignity of life.A systematic review was conducted to identify models of advancecare planning information sharing and to examine the nurses’role. A realist review comprising a metasynthesis of 8 qualitativestudies and 9 quantitative studies was conducted. Nursingcompetencies need to be developed to include the medico-legalframework around advance care plan development, as well asinformation technology competencies and communicationcompetencies so that nurses around the world are betterinformed for end-of-life care planning and practice in a digitalworl