16 research outputs found
The design and use of the Bioethics Consultation Form
The emergence of the ethics consultation as a means to resolve moral crises in clinical medicine has revealed the need for a worksheet that would facilitate intake and analysis. The author developed the “Bioethics Consultation Form” as an attempt to remedy this need. The form is arranged in an outline format and is a useful asset to ethics committee discussions and record keeping. The first section covers basic intake data concerning the patient's medical and personal information, advance directives, and values, as well as the values of the physician and family. After the intake section is completed with the above data, the ethics consultant then turns to the analysis section. This second section allows for (1) the discussion of conflicting values, (2) the identification of priorities, and (3) the elucidation of ethical norms relevant to the case.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43229/1/11017_2004_Article_BF00489215.pd
Construction of a Mean Square Error Adaptive Euler--Maruyama Method with Applications in Multilevel Monte Carlo
A formal mean square error expansion (MSE) is derived for Euler--Maruyama
numerical solutions of stochastic differential equations (SDE). The error
expansion is used to construct a pathwise a posteriori adaptive time stepping
Euler--Maruyama method for numerical solutions of SDE, and the resulting method
is incorporated into a multilevel Monte Carlo (MLMC) method for weak
approximations of SDE. This gives an efficient MSE adaptive MLMC method for
handling a number of low-regularity approximation problems. In low-regularity
numerical example problems, the developed adaptive MLMC method is shown to
outperform the uniform time stepping MLMC method by orders of magnitude,
producing output whose error with high probability is bounded by TOL>0 at the
near-optimal MLMC cost rate O(TOL^{-2}log(TOL)^4).Comment: 43 pages, 12 figure
G protein-coupled receptor-mediated calcium signaling in astrocytes
Astrocytes express a large variety of G~protein-coupled receptors (GPCRs)
which mediate the transduction of extracellular signals into intracellular
calcium responses. This transduction is provided by a complex network of
biochemical reactions which mobilizes a wealth of possible calcium-mobilizing
second messenger molecules. Inositol 1,4,5-trisphosphate is probably the best
known of these molecules whose enzymes for its production and degradation are
nonetheless calcium-dependent. We present a biophysical modeling approach based
on the assumption of Michaelis-Menten enzyme kinetics, to effectively describe
GPCR-mediated astrocytic calcium signals. Our model is then used to study
different mechanisms at play in stimulus encoding by shape and frequency of
calcium oscillations in astrocytes.Comment: 35 pages, 6 figures, 1 table, 3 appendices (book chapter
A Test Set for Molecular Dynamics Algorithms
This article describes a collection of model problems for aiding numerical analysts, code developers and others in the design of computational methods for molecular dynamics (MD) simulation. Common types of calculations and desirable features of algorithms are surveyed, and these are used to guide selection of representative models. By including essential features of certain classes of molecular systems, but otherwise limiting the physical and quantitative details, it is hoped that the test set can help to facilitate cross-disciplinary algorithm and code development efforts