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Correction factors, termed α-factors, similar to those defined by LaChance and Traill have been generated by the addition of variable, known amounts of individual oxides, or other compounds, to a base cement sample and measuring the x-ray intensities of the elements of interest. The effects of all common constituents of cement on the determination of CaO, SiO2 and Al2O3 were found. Factors for rhodium and chromium primary radiation were determined and, in general, showed small but significant differences. The factors for rhodium at 50kV and 30kV were substantia11y identical. The correction factors were tested through the use of the NBS 1011- 1016 cements as reference standards to analyze the new proposed NBS cement series. The correction factors not only furnished improved calibration curves, but also allowed the determination of CaO, Al2O3 and SiO2 with an average deviation of less than 0.2% (absolute) from the provisional values furnished with the standard samples.
Persecutory delusions are a key psychotic experience. A reasoning style known as ‘jumping to conclusions’ (JTC) – limited information gathering before reaching certainty in decision making – has been identified as a contributory factor in the occurrence of delusions. The cognitive processes that underpin JTC need to be determined in order to develop effective interventions for delusions. In the current study two alternative perspectives were tested: that JTC partially results from impairment in information-processing capabilities and that JTC is a motivated strategy to avoid uncertainty.
A group of 123 patients with persistent persecutory delusions completed assessments of JTC (the 60:40 beads task), IQ, working memory, intolerance of uncertainty, and psychiatric symptoms. Patients showing JTC were compared with patients not showing JTC.
A total of 30 (24%) patients with delusions showed JTC. There were no differences between patients who did and did not jump to conclusions in overall psychopathology. Patients who jumped to conclusions had poorer working memory performance, lower IQ, lower intolerance of uncertainty and lower levels of worry. Working memory and worry independently predicted the presence of JTC.
Hasty decision making in patients with delusions may partly arise from difficulties in keeping information in mind. Interventions for JTC are likely to benefit from addressing working memory performance, while in vivo techniques for patients with delusions will benefit from limiting the demands on working memory. The study provides little evidence for a contribution to JTC from top-down motivational beliefs about uncertainty.
Aeroacoustic power generation due to a self-sustained oscillation by an axisymmetric compact cavity exposed to a low-Mach-number grazing flow is studied both experimentally and numerically. The feedback effect is produced by the velocity fluctuations resulting from a coupling with acoustic standing waves in a coaxial pipe. A numerical methodology that combines incompressible flow simulations with vortex sound theory is used to predict the time-averaged acoustic source power generated by the cavity. The effect of cavity depth on the whistling is addressed. It is observed that the whistling occurs around a peak-whistling Strouhal number which depends on the cavity depth to width ratio. The proposed numerical method provides excellent predictions of the peak-whistling Strouhal number as a function of cavity depth. Given the oscillation amplitude, the numerical method predicts the time-averaged acoustic source power within a factor of two for moderate fluctuation amplitudes. For deep cavities the time-averaged acoustic source power appears to be independent of the cavity depth.
The efficacy of lithium prophylaxis in bipolar affective disorder in clinical practice was investigated. Comparison was made between 41 patients who were prescribed prophylactic lithium after two admissions in two years or three admissions in five years and a group of patients who did not receive lithium. The benefits conferred by the prescription of this drug were modest compared with the results from clinical trials.
Nuclear magnetic resonance images of the brain were obtained in fourteen patients with major depression during a course of ECT. The T1, relaxation time rose immediately after the fit reaching a maximum 4–6 h later. The T1, values then returned to their original level; no long-term increase occurred over the course of treatment. These results are consistent with an extensive but temporary breakdown of the blood-brain barrier during ECT.