Tableaux and Systemes : Early French contributions to linear production models

Properly speaking the history of linear production modelling begins in the second half of the 18th century. A comparison between Francois Quesnay's Tableaux economiques and Achilles-Nicolas Isnard’s systèmes des richesses provides insights into the various possible directions within this nascent branch of economic analysis. Quesnay presents an idealised model of the French economy, making a number of limiting assumptions to study phenomena of economic growth and decline. Isnard's approach is more general and abstract and focuses on the interplay between reproduction, prices and distribution. The conceptual difficulties in their works, such as Quesnay's implicit assumption of unchanging prices and Isnard's lack of rules for the distribution of the surplus, were encountered again, and solved in different ways, by later theorists such as Leontief, von Neumann and Sraffa

A time of flight method to measure the speed of sound using a stereo sound card

We present an inexpensive apparatus for measuring the speed of sound, with a time of flight method, using a computer with a stereo sound board. Students measure the speed of sound by timing the delay between the arrivals of a pulse to two microphones placed at different distances from the source. It can serve as a very effective demonstration, providing a quick measurement of the speed of sound in air; we have used it with great success in Open Days in our Department. It can also be used for a full fledged laboratory determination of the speed of sound in air.Comment: Accepted for publication in The Physics Teache

Instanton size distribution in O(3)

We present calculations of the size distribution of instantons in the 2d O(3) non-linear sigma-model, and briefly discuss the effects cooling has upon the configurations and the topological objects. (This preprint is also available via anonymous ftp to suna.amtp.liv.ac.uk in /pub/pss/ as instdist.uue.)Comment: 17 pages, LaTeX, needs cite.sty (appended), with appended uuencoded compressed tarfile of PostScript figures, Liverpool preprint LTH-33

Adjustment of nursing home quality indicators

Background: This manuscript describes a method for adjustment of nursing home quality indicators (QIs) defined using the Center for Medicaid & Medicare Services (CMS) nursing home resident assessment system, the Minimum Data Set (MDS). QIs are intended to characterize quality of care delivered in a facility. Threats to the validity of the measurement of presumed quality of care include baseline resident health and functional status, pattern of comorbidities, and facility case mix. The goal of obtaining a valid facility-level estimate of true quality of care should include adjustment for resident- and facility-level sources of variability. Methods: We present a practical and efficient method to achieve risk adjustment using restriction and indirect and direct standardization. We present information on validity by comparing QIs estimated with the new algorithm to one currently used by CMS. Results: More than half of the new QIs achieved a "Moderate" validation level. Conclusions: Given the comprehensive approach and the positive findings to date, research using the new quality indicators is warranted to provide further evidence of their validity and utility and to encourage their use in quality improvement activities

Adjustment of nursing home quality indicators

Abstract Background This manuscript describes a method for adjustment of nursing home quality indicators (QIs) defined using the Center for Medicaid & Medicare Services (CMS) nursing home resident assessment system, the Minimum Data Set (MDS). QIs are intended to characterize quality of care delivered in a facility. Threats to the validity of the measurement of presumed quality of care include baseline resident health and functional status, pattern of comorbidities, and facility case mix. The goal of obtaining a valid facility-level estimate of true quality of care should include adjustment for resident- and facility-level sources of variability. Methods We present a practical and efficient method to achieve risk adjustment using restriction and indirect and direct standardization. We present information on validity by comparing QIs estimated with the new algorithm to one currently used by CMS. Results More than half of the new QIs achieved a "Moderate" validation level. Conclusions Given the comprehensive approach and the positive findings to date, research using the new quality indicators is warranted to provide further evidence of their validity and utility and to encourage their use in quality improvement activities.http://deepblue.lib.umich.edu/bitstream/2027.42/112501/1/12913_2009_Article_1233.pd

PCR-based genotyping of Helicobacter pylori of Gambian children and adults directly from biopsy specimens and bacterial cultures

<p>Abstract</p> <p>Background</p> <p><it>Helicobacter pylori </it>is an important agent of gastroduodenal disease in Africa and throughout the world. We sought to determine an optimum method for genotyping <it>H. pylori </it>strains from children and adults in The Gambia, West Africa.</p> <p>Results</p> <p>Virulence genes were amplified in 127 of 190 cases tested (121 adults and 6 children); each of 60 bacterial cultures, and 116 from DNA extracted directly from biopsies. The proportion of biopsies that were <it>cagA</it>+, the ratio of <it>vacAs1</it>/<it>s2</it>, and <it>vacAm1</it>/<it>m2</it>, and the proportion of mixed strain populations in individual subjects changed with age. Strains lacking virulence <it>cagA </it>and <it>vacA </it>genes and with apparently homogeneous (one predominant strain) infections were more common among infants than adults.</p> <p>Conclusions</p> <p>In order to detect the range of bacterial genotypes harbored by individual patients, direct PCR proved slightly superior to isolation of <it>H. pylori </it>by biopsy culture, but the techniques were complementary, and the combination of both culture and direct PCR produced the most complete picture. The seemingly higher virulence of strains from adult than infant infections in The Gambia merits further analysis.</p

Elevation of the Basal Sand and Gravel of the Middle Illinois River Valley, Bureau, LaSalle, Marshall, Peoria, Putnam, and Woodford Counties, Illinois

Illinois Department of Transportationpublished or submitted for publicatio

FDTD and FEM/MOM Modeling of EMI Resulting from a Trace Near a PCB Edge

PCB traces routed near board edges and carrying high-speed signals are considered to contribute to EMI problems. Consequently, design maxims state that traces that might have intentional or unintentional high frequency components on them be kept away from board edges. This costs valuable surface area as boards become more densely designed. Further, design maxims concerning traces near board edges are not well quantified. The increase in EMI as a trace is routed increasingly closer to the PCB edge has been studied experimentally and with numerical modeling