Performance of a lead glass spectrometer at high energies

The performance of a photon detector consisting of two lead glass arrays and three planes of proportional tubes is reported. The detector was designed to measure the energies and positions of photons in the energy range 3–50 GeV. An energy resolution of $\text{1.0\% +}\text{5.0\%}\text{√E}$ (standard deviation) and a spatial resolution approaching 3 mm (standard deviation) were achieved during calibration with a low intensity positron beam. The energy resolution was degraded during use with a high intensity hadron beam whereas the spatial resolution was only slightly affected.     

Noisy image restoration by cost function minimization

Implementation of a new approach to the nonlinear noisy image restoration problem, which is feasible for large images, is described. The approach is based on a vector space representation of images and on using the conjugate gradient algorithm to solve a least squares minimization problem. Computer simulations yield good results with relatively little computational cost.     

Logic Programming and Prolog: A Tutorial

Logic programming offers significant advantages for the massively parallel computer systems of tomorrow. This tutorial examines the potential of Prolog to implement those advantages.     

Environmental and adhesive durability of aluminium-polymer systems protected with organic corrosion inhibitors

The protection of pretreated aluminium against environmental corrosion has been accomplished in varying degrees by incorporating selected organophosphonates and organosilanes on the metal surface. lonizable phosphonates, such as nitrilo-tris methylene phosphonic acid (NTMP), adsorbed at monolayer concentrations, are effective inhibitors against hydration and are compatible with a nitrile-modified epoxy adhesive material. Aqueous 0.1 vol% solutions of selected organosilane compounds containing reactive side chains (e.g. epoxy, mercapto) exhibit protection against both hydration corrosion and the action of an aggressive species (Cl^–) and provide good adhesive bond durability with both nitrile-modified and polyamide (primer) epoxy resin systems. Wedge test results suggest that the curing process (e.g. the percentage crosslinking) of the epoxy-polyamide primer system is not affected by the addition of organosilanes, but may be affected by NTMP. The results of substrate surface characterization, adsorption behaviour of applied films, and evaluation of candidate inhibitors by chemical, mechanical, and electrochemical test methods are presented. Mechanisms to explain the observed behaviour of the phosphonate and silane systems are discussed.     

Job-shop development model: a case study

Traditional effort-estimation models can be frustrating, especially when staff are divided among multiple projects. The authors evaluate a model based on dividing activities into jobs. It accounts for divided time and more accurately categorizes rework costs. The model lets organizations represent software development in more detail than they can with many existing models. By breaking each project into batches and each batch into jobs, the model recognizes that, at any point in time, parts of the software may be at different stages of completion     

Pattern recognition properties of various feature spaces for higherorder neural networks

The authors explore alternatives that reduce the number of network weights while maintaining geometric invariant properties for recognizing patterns in real-time processing applications. This study is limited to translation and rotation invariance. The primary interest is in examining the properties of various feature spaces for higher-order neural networks (HONNs), in correlated and uncorrelated noise, such as the effect of various types of input features, feature size and number of feature pixels, and effect of scene size. The robustness of HONN training is considered in terms of target detectability. The experimental setup consists of a 15×20 pixel scene possibly containing a 3×10 target. Each trial used 500 training scenes plus 500 testing scenes. Results indicate that HONNs yield similar geometric invariant target recognition properties to classical template matching. However, the HONNs require an order of magnitude less computer processing time compared with template matching. Results also indicate that HONNs could be considered for real-time target recognition applications     

Cryptosporidiosis in Wisconsin: a case-control study of post-outbreak transmission

During March-April 1993, an estimated 403000 residents of the 5-county greater Milwaukee, Wisconsin area developed cryptosporidiosis after drinking contaminated municipal water. Although the number of cases dropped precipitously after the implicated water plant closed on 9 April, cases continued to occur. To investigate risk factors for post-outbreak cryptosporidiosis, 33 Milwaukee-area residents who had laboratory-confirmed Cryptosporidium infection with onset of diarrhoea between 1 May and 27 June 1993 were interviewed by telephone. Of these, 28 (85%) had onset of diarrhoea during May, 12 (36%) had watery diarrhoea during the outbreak, and 5(15%) were HIV-infected. In a neighbourhood-matched case-control study, immunosuppression (matched odds ratio (MOR) not calculable, 95% confidence interval (CI) 3.0, infinity) and having a child less than 5 years old in the household (MOR = 17.0, CI 2.0, 395.0) were independently associated with infection. When persons who had diarrhoea during the outbreak were excluded, immunosuppression remained significantly associated with illness (MOR not calculable, CI 1.6, infinity). Cryptosporidium transmission continued after this massive waterborne outbreak but decreased rapidly within 2 months.