PubMed · 10250250
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E W Lambert. 1981. Program evaluation data: who needs it? Assessing the need for evaluation.. https://doi.org/10.1007/bf02828487
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The application of solvent microextraction to the analysis of nitroaromatic explosives is presented. Extraction of 11 nitroaromatics was achieved by suspending 1 microl of organic solvent to the tip of a microsyringe in a stirred aqueous solution. Parameters such as extraction solvent, stirring rate, salt concentration and sampling time were studied and optimized. The limits of detection using bench-top quadrupole mass spectrometry and short extraction times (15 min) were found to be between 0.08 and 1.3 microg/l and the relative standard deviations ranged between 4.3 and 9.8%. Although precision and accuracy of quantification of the method are still needed, solvent microextraction proved to be a fast, simple and inexpensive tool for preconcentration and matrix isolation of nitroaromatics on a microscale.
Dr. Firth-Cozens begins her paper by reviewing a broad range of research related to physicians' stress, depression, and alcoholism (Firth-Cozens, 2001, Social Science and Medicine, 52, 215-222). She then argues that these psychological problems have a negative impact on patient care and describes the possible causes of these problems. Finally, she proposes a system of organizational and individual interventions to address these problems. Before accepting her conclusions and proposed system of interventions, an important issue should be considered. Is physicians' well-being an important goal in and of itself, or do we need strong evidence that physician stress, depression, and alcoholism lead to poor patient care and outcomes?
PURPOSE: To evaluate the imaging characteristics of an amorphous silicon flat-panel detector (FPD) for digital chest radiography. MATERIALS AND METHODS: The 41 x 41-cm digital FPD is constructed on a single monolithic glass substrate with a structured cesium iodide scintillator layer and an amorphous silicon thin-film transistor array for image readout. Basic imaging characteristics of the FPD and associated image processing system were assessed on acquired images, including linearity, repeatability, uniformity of response, modulation transfer function (MTF), noise power spectrum, detective quantum efficiency (DQE), contrast sensitivity, and scatter content. Results with the FPD system were compared to those with a storage phosphor computed radiography (CR) system. RESULTS: Images obtained with the FPD demonstrated excellent uniformity, repeatability, and linearity, as well as MTF and DQE that were superior to those with the storage phosphor CR system. The contrast and scatter content of images acquired with the FPD were equivalent to those acquired with the storage phosphor system. CONCLUSION: The FPD provides radiographic images with excellent inherent physical image quality.