Digital Imaging of Gamma-Ray Sources with Depth Information

A digital method for imaging gamma-ray emitting organs recorded through a Fresnel zone plate (FZP) aperture is described. This technique can be used in an almost real-time recording and imaging system to yield quantitative and qualitative cross-section and depth information of the source. Furthermore, this method avoids some of the problems introduced by the usual method of optical reconstruction. Experimental results of the recording of a multiplane gamma-ray source and the reconstruction of digitally and optically formed images are also presented.     

White-light holographic system to compensate phase distortion

A compact, passive, holographic system is proposed which compensates arbitrary phase distortion in an incoherently illuminated imaging system.     

The economic cost of the medical-legal tort system

OBJECTIVE: Our goal was to evaluate the financial expenditures of the medical-legal tort system on the single largest medical campus in the United States. STUDY DESIGN: The true financial expenditures directed to the medical-legal system were determined and related to the total revenue and expenses of the Detroit Medical Center. All costs were determined, including malpractice premiums, paid claims information, accrual expense information, and risk management administrative expenses for the fiscal years 1992, 1993, and 1994. RESULTS: The total medical-legal expenses for the years 1992, 1993, and 1994 were $73,732,000, $70,490,000, and $79,043,000, respectively. The claims paid to plaintiffs were 35.9%, 28.1%, and 28.1% for the same years. CONCLUSION: The medical-legal system process in the United States is very long and fraught with many inequities and inefficiencies. It was found that approximately 12% of the medical-legal expenditures of the Detroit Medical Center go to the individual alleged victim after defense and plaintiff attorney fees and costs and administrative costs. The failure of the American health care system could be in jeopardy if the nation's leaders do not reform the process to provide a more cost-effective system.     

The connection function–theory and application

An approach to circuit theory is presented wherein the connections are modelled as a system valued function of a system valued variable. It is shown that for a large class of circuits and systems that this nonlinear function can be viably represented by four matrices through which it may be readily manipulated, both theoretically and computationally. The elementary properties of the connection function are derived and the approach is illustrated through a number of applications. In particular, an explicit formula for the sensitivity of a circuit in terms of the sensitivity of its components is obtained; and a semi-analytic solution to a class of CAD problems is formulated.     

An adsorption study of hydrogen on iron and its relation to hydrogen embrittlement

The chemical reactions of hydrogen gas on iron surfaces have been determined by simultaneously measuring the volume of gas adsorbed and the corresponding magnetization change. The combination of these experimental results as well as the kinetics of the reactions is used to explain the temperature dependence observed in crack growth studies performed in gaseous hydrogen. The reaction is shown to be a two step process involving the formation of an adsorbed molecular precursor prior to the formation of the embrittling hydrogen ion. The adsorption isotherm and magnetizationadsorption isotherm for H₂ on Fe at 77 K were determined to be Langmuirian. This, plus a first order adsorption rate are given as evidence for the existence of a chemisorbed molecular H ₂ ⁺ precursor at this temperature. The mechanical test data of other investigators for slow crack growth in gaseous H₂, which show a nonmonotonic change of crack growth rate with temperature, become explainable based on a measured decrease in the adsorption of H₂ at temperature above 300 K and the two step adsorption process. At temperatures below 300 K the formation of an H^- ion from the adsorbed precursor H ₂ ⁺ ion is the rate controlling process in gaseous hydrogen embrittlement. At temperatures above 300 K, the decreasing net adsorption rate of H ₂ ⁺ becomes the limiting process. Formerly Graduate Student, Syracuse University.