Improved lithium-drifted silicon solid-state detectors allow detection and energy dispersion of x-rays of about 3 to 30 kiloelectron volts in the electron-microprobe x-ray analyzer. Energy resolution is sufficient to separate peaks of characteristic x-rays of elements adjacent in the periodic system at atomic number 20 and higher. The detected x-ray spectrum emitted from an unknown sample can be recorded with a multichannel analyzer in approximately 60 seconds.

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This study compares the antipsychotic efficacy and the tolerability of risperidone and clozapine in patients with schizophrenia. Patients were randomized to double-blind treatment with risperidone, 4 mg (N = 20), risperidone, 8 mg (N = 19), or clozapine, 400 mg (N = 20), daily for 28 days. Efficacy was assessed by improvement of psychotic symptoms, measured on the Brief Psychiatric Rating Scale, and Clinical Global Impression. The tolerability was assessed by the Simpson and Angus scale for extrapyramidal side effects (EPS), the Association for Methodology and Documentation in Psychiatry (AMDP) scale for somatic side effects, spontaneous reports of adverse events, clinical laboratory assessments, and vital signs. All treatments reduced psychotic symptoms. The global tolerability was significantly better in the risperidone than in the clozapine-treated patients (p < 0.01). There were no differences between treatments on the AMDP scale. The most frequent spontaneously reported adverse effects were dizziness, fatigue, accommodation disturbance, and EPS in all treatment groups and increased salivation, mainly in the clozapine-treated patients. Although there were no changes in vital signs during risperidone treatment, clozapine was associated with a mean reduction in heart rate of 10 beats/minute. Risperidone tolerability at endpoint was classified as "very good" by 60 and 47% of patients treated with risperidone, 4 and 8 mg daily, respectively; the corresponding figure in clozapine-treated patients was 30%. The results suggest that risperidone is at least as effective as an antipsychotic as clozapine, providing a valuable new approach for the treatment of schizophrenia.

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Part of the mission of NBS is to disseminate knowledge in the scientific and technical community.To aid in reaching this objective, the Analytical Chemistry Division has sponsored a series of workshops on various topics in analytical chemistry. The workshop topics are chosen to fulfill current needs for detailed discussions on sharply defined subjects in a wide variety of specialist areas.The objective is to bring together specialists from throughout the world to concentrate intensively on a particular subject in order to advance the state-of-the-art.It is often very difficult to achieve this goal at large international meetings where the size and diversity of topics presented often limits detailed discussion of special subjects.Past topics of these workshops and the published proceedings include:Quantitative The workshop format consisted of a keynote talk on each topic followed by extensive discussions. The papers in this volume are based on the keynote talks augmented with some points raised in the discussion.The extensive development of electron beam instrumentation for the microscopy and analysis of samples of diverse scientific interest has resulted in a need for detailed studies of the origin and characteristics of the signals involved. This publication provides a detailed view of one approach to the study of such signals, namely the Monte Carlo technique for electron trajectory calculation.The publication should be of value to the numerous workers who utilize the scanning electron microscope and electron probe microanalyzer. The utility of electron probe microanalysis and scanning electron microscopy is demonstrated by the fact that more than 2500 such instruments costing from $25,000 to $200,000 are now in use worldwide, and more instruments are constantly being added. Moreover, the instruments are at work in fields as diverse as biology, metallurgy, electronics, chemistry, and forensic science.Simultaneously with the development and distribution of the instrumentation, much work has been devoted to the study of electron interactions with solids with the purpose of characterizing the signals which are utilized in microscopy and analysis.One approach which has proven especially useful in both qualitative and quantitative studies of electron interactions is that of Monte Carlo electron trajectory simulation.Monte Carlo calculations have enabled scientists to visualize the electron interaction volume in solids as to size and shape, to predict the parameters characterizing the secondary and back-scattered electrons, the x-rays, and the Auger electrons, and to analyze factors which determine resolution in micrographs.The purpose of the present workshop was to bring together a number of workers in Monte Carlo trajectory techniques to assess the current state of development and to look for areas of future development.The list of participants in the meeting does not include all active workers in the field, but we hope that this document contains a reasonably complete description of the subject.By examining the a...

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LITERATURE CITEDMore detailed discussion of the -ray interferences is given in earlier work (78).3) As already mentioned above, the possibilities of nuclear interferences are few at 10 MeV. It may be seen in column 3, Table I, that the only interference is between Li and B, 7Be is produced by 7Li(p,n)7Be and by 10B(p,o:)7Be.No other interference was detected by direct -ray spectrometry of elements irradiated at 10 MeV. With chemical separations, it would probably be possible to observe some ( , ) reactions on the lighter elements. Anyhow, if one considers all the Q-values for the nuclear reactions and the relative positions of the stable and of the radioactive isotopes for the studied elements, one sees that for all of them it is possible to find a suitable and interference free (p,n) reaction (except for Li and B). CONCLUSIONS 10-MeV proton activation may be used for the determination of trace concentrations of the 22 elements studied in this work; 47 radioisotopes and over 100 associated -rays are obtained via (p,n) reactions, thus offering a great choice to perform the analysis and a great selectivity (except for Li and B).This study was complemented by an application to the analysis of trace elements in 19 different matrices. In the case of these 19 matrices, 10-MeV proton activation is a powerfull technique because it is sensitive, selective, and also nondestructive.

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