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56 results on '"Jeremy Stewart"'

51. High speed numerical integration of Fermi Dirac integrals

Author

Thompson, Jeremy Stewart., Luscombe, James H., Walters, Donald Lee, Naval Postgraduate School, and Department of Physics

Subjects
Fermi Dirac integrals solved by numerical methods
Abstract

In this thesis we present an algorithm for the precise determination of Fermi-Dirac (FD) integral functions, for arbitrary values of the parameter and the argument. The FD integrals are a class of functions that are used extensively in the modeling of semiconductor devices, e.g., when the charge carriers are in a strongly quantum, degenerate regime, such as in heavily doped semiconductors. The determination of FD integrals has a long history. Our approach to evaluating these functions is two-fold. First, we develop exact power series expansions of the integral. These series, however, converge too slowly to be a practical means of evaluating the integral. The second aspect of our approach is to apply numerical series acceleration methods to improve significantly the rate of convergence of these series expansions. The result is a computer program that provides efficient, accurate values of the FD integral. http://archive.org/details/highspeednumeric109458472 Lieutenant, United States Navy Approved for public release; distribution is unlimited.

Published
1996

53. High speed numerical integration of Fermi Dirac integrals

Author

Luscombe, James H., Walters, Donald Lee, Naval Postgraduate School, Department of Physics, Thompson, Jeremy Stewart., Luscombe, James H., Walters, Donald Lee, Naval Postgraduate School, Department of Physics, and Thompson, Jeremy Stewart.

Abstract

In this thesis we present an algorithm for the precise determination of Fermi-Dirac (FD) integral functions, for arbitrary values of the parameter and the argument. The FD integrals are a class of functions that are used extensively in the modeling of semiconductor devices, e.g., when the charge carriers are in a strongly quantum, degenerate regime, such as in heavily doped semiconductors. The determination of FD integrals has a long history. Our approach to evaluating these functions is two-fold. First, we develop exact power series expansions of the integral. These series, however, converge too slowly to be a practical means of evaluating the integral. The second aspect of our approach is to apply numerical series acceleration methods to improve significantly the rate of convergence of these series expansions. The result is a computer program that provides efficient, accurate values of the FD integral.

Published
1996

54. Multiplexing a High-Throughput Liability Assay to Leverage Efficiencies.

Author

John Herbst, Monique Anthony, Jeremy Stewart, David Connors, Taosheng Chen, Martyn Banks, Edward W. Petrillo, and Michele Agler

Subjects
HIGH throughput screening (Drug development), BIOLOGICAL assay, CYTOCHROME P-450, DRUG metabolism, DRUG development, NUCLEAR receptors (Biochemistry), CELL lines, LIVER cells, CANCER cells
Abstract

In order to identify potential cytochrome P-450 3A4 (drug-metabolizing enzyme) inducers at an early stage of the drug discovery process, a cell-based transactivation high-throughput luciferase reporter assay for the human pregnane X receptor (PXR) in HepG2 cells has been implemented and multiplexed with a viability end point for data interpretation, as part of a Lead Profiling portfolio of assays. As a routine part of Lead Profiling operations, assays are periodically evaluated for utility as well as for potential improvements in technology or process. We used a recent evaluation of our PXR-transactivation assay as a model for the application of Lean Thinking-based process analysis to lab-bench assay optimization and automation. This resulted in the development of a 384-well multiplexed homogeneous assay simultaneously detecting PXR transactivation and HepG2 cell cytotoxicity. In order to multiplex fluorescent and luminescent read-outs, modifications to each assay were necessary, which included optimization of multiple assay parameters such as cell density, plate type, and reagent concentrations. Subsequently, a set of compounds including known cytotoxic compounds and PXR inducers were used to validate the multiplexed assay. Results from the multiplexed assay correlate well with those from the singleplexed assay formats measuring PXR transactivation and viability separately. Implementation of the multiplexed assay for routine compound profiling provides improved data quality, sample conservation, cost savings, and resource efficiencies. [ABSTRACT FROM AUTHOR]

Published
2009
Full Text
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55. Salvinorin A, an active component of the hallucinogenic sage salvia divinorum is a highly efficacious kappa-opioid receptor agonist: structural and functional considerations.

Author

Charles, Chavkin, Sumit, Sud, Wenzhen, Jin, Jeremy, Stewart, K, Zjawiony Jordan, J, Siebert Daniel, Ann, Toth Beth, J, Hufeisen Sandra, and L, Roth Bryan

Abstract

The diterpene salvinorin A from Salvia divinorum has recently been reported to be a high-affinity and selective kappa-opioid receptor agonist (Roth et al., 2002). Salvinorin A and selected derivatives were found to be potent and efficacious agonists in several measures of agonist activity using cloned human kappa-opioid receptors expressed in human embryonic kidney-293 cells. Thus, salvinorin A, salvinorinyl-2-propionate, and salvinorinyl-2-heptanoate were found to be either full (salvinorin A) or partial (2-propionate, 2-heptanoate) agonists for inhibition of forskolin-stimulated cAMP production. Additional studies of agonist potency and efficacy of salvinorin A, performed by cotransfecting either the chimeric G proteins Gaq-i5 or the universal G protein Ga16 and quantification of agonist-evoked intracellular calcium mobilization, affirmed that salvinorin A was a potent and effective kappa-opioid agonist. Results from structure-function studies suggested that the nature of the substituent at the 2-position of salvinorin A was critical for kappa-opioid receptor binding and activation. Because issues of receptor reserve complicate estimates of agonist efficacy and potency, we also examined the agonist actions of salvinorin A by measuring potassium conductance through G protein-gated K(+) channels coexpressed in Xenopus oocytes, a system in which receptor reserve is minimal. Salvinorin A was found to be a full agonist, being significantly more efficacious than (trans)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl] benzeneacetamide methane-sulfonate hydrate (U50488) or (trans)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl] benzeneacetamide methane-sulfonate hydrate (U69593) (two standard kappa-opioid agonists) and similar in efficacy to dynorphin A (the naturally occurring peptide ligand for kappa-opioid receptors). Salvinorin A thus represents the first known naturally occurring non-nitrogenous full agonist at kappa-opioid receptors.

Published
2004

56. High speed numerical integration of Fermi Dirac integrals

Author

Luscombe, James H., Walters, Donald Lee, Naval Postgraduate School, Department of Physics, Thompson, Jeremy Stewart., Luscombe, James H., Walters, Donald Lee, Naval Postgraduate School, Department of Physics, and Thompson, Jeremy Stewart.

Abstract

In this thesis we present an algorithm for the precise determination of Fermi-Dirac (FD) integral functions, for arbitrary values of the parameter and the argument. The FD integrals are a class of functions that are used extensively in the modeling of semiconductor devices, e.g., when the charge carriers are in a strongly quantum, degenerate regime, such as in heavily doped semiconductors. The determination of FD integrals has a long history. Our approach to evaluating these functions is two-fold. First, we develop exact power series expansions of the integral. These series, however, converge too slowly to be a practical means of evaluating the integral. The second aspect of our approach is to apply numerical series acceleration methods to improve significantly the rate of convergence of these series expansions. The result is a computer program that provides efficient, accurate values of the FD integral., http://archive.org/details/highspeednumeric109458472, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

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