Design and simulation of waveguide electrooptic beam deflectors

Numerical simulation based on the scalar beam propagation method, was used to investigate the performance of waveguide electrooptic beam deflectors. The deflectors under investigation consist of a stack of electrooptically controlled prisms in a waveguide. The results were compared to earlier simplified analysis. It was found that for given overall device dimensions, the number of interfaces between prisms in a prism-type electrooptic deflector has significant influence on the device performance when it is small. To avoid wavefront distortion, unwanted reflection from the interfaces, and asymmetry in the deflection angles caused by small number of interfaces, one should use more than about ten interfaces in a typical deflector. Additional insights of device operation and design issues are discussed     

An economic evaluation of the use of rare earth screens to reduce the radiation dose from diagnostic X-ray procedures in Israel

In Israel the diffusion of rare earth screen technology has been limited. These screens could halve the radiation dose to the patient from diagnostic X-ray radiography, with little managerial effort and without being detrimental to the quality of the diagnostic image. We estimated the total effective dose from diagnostic film radiography capable of reduction by the use of rare earth screens, based on the number of hospital and ambulatory diagnostic X-ray procedures. This number was multiplied by the computed radiation dose per body site for a series of diagnostic procedures. The annual dose was approximately 0.53 mSv per head, approximately half of which could be averted by the introduction of rare earth screen technology. Based on a fatality risk of 3% Sv-1, it is estimated that the adoption of rare earth screen technology might reduce the annual incidence of cancer by some 93 cases, half of which would be fatal after an average latency period of 18.4 years. The cost of purchasing rare earth screens on a nationwide basis is approximately $3.0 million. This cost is outweighed by a saving of $9.6 million in X-ray tube replacement costs over the period 1997-2006. Government legislation enforcing the use of rare earth screens is essential, because of the lack of prestige associated with acquiring rare earth technology, as well as institutional reluctance to accept the external benefits of reduced morbidity and mortality and/or to extend budgetary time horizons.     

Mycobacterium tuberculosis and the complement system

Accumulated evidence to date confirms the importance of the C3-CR pathway in the phagocytosis of pathogenic mycobacteria. Detailed receptor-ligand studies for phagocytosis are creating the framework to test the hypothesis that the entry pathway for these bacteria influences the immediate host cell response and their intracellular fate. These types of study are particularly important for improving our understanding of the outcome of primary infection in humans, where the number of bacilli is presumed to be very low.     

Phase diagram prediction of Δf G 0 for inter metallic compounds: A ‘sensitivity’ analysis

The prediction of the free energies of formation of intermetallic phases in binary systems typically involves assuming that the liquidus (or solvus) compositions in equilibrium with the phase are correct, that the measured thermodynamic properties of the adjacent solution are reliable enough to be extrapolated to different compositions and temperatures, that the thermodynamic solution model is of sufficient complexity to make such extrapolations accurate, and that the solid- solubility range of the intermetallic phase is negligible. These assumptions often conflict with the actual circumstances for a given system,leading to some question of how these errors would affect model-predicted Δ _f G ⁰ values. Analysis of four binary systems (Ca- Zn, Al- Au, Ni- Ti, and Co-Sn) shows that poor-quality thermodynamic data has an especially strong impact on predictions, which can be exacerbated by the use of more sophisticated thermodynamic models. Compound nonstoichiometry and controversial liquidus compositions have less impact on modeling results.     

Three-Chromophore Compounds I. Reductive Transformations of the 3,5-diaryl-2-cyclohexen-1-ones

The preparation of three 3,5-diarylcyclohexanones by rhodiumchlorotris(triphenyl-phosphine)—catalyzed reduction of the parent olefines (IIa—IIc) is described. Other reducing agents produced several intermediate products of the total hydrogenolysis.     

Thermodynamic properties of alumina-saturated iron-carbon-bismuth alloys

Using direct and indirect equilibration methods, the solubilities of iron in molten bismuth and those of bismuth in molten iron-carbon alloys have been measured over the temperature range 1473-1873 K. The Henrian behaviour of bismuth in molten ferrous alloys allows the calculation of its activity coefficient, which in turn facilitates modelling as a function of temperature and carbon content, using the unified interaction parameter formalism developed by Pelton and Bale. The modelling results generate the expression: . A model has also been developed expressing bismuth content in molten iron-carbon alloys as a function of temperature and composition: .     

Creative mythconceptions: A closer look at the evidence for the "mad genius" hypothesis.

Many people believe that the “mad genius” notion, which has been a favorite cultural fixture for centuries, is based on established scientific fact. Much of the evidence for the connection between great creativity and great pathology, particularly affective disorder, comes from the writings of psychiatrists Nancy Andreasen and Arnold K. Ludwig and psychologist Kay Redfield Jamison. For two decades, their studies and books have been widely referenced in both the popular and professional press without critique or comment and often without much detail, suggesting that few people have spent much time with the originals. This article examines their most influential works, encouraging readers to evaluate this evidence for themselves, because the author believes that many of their claims have had unfortunate implications for the perception of creativity and the credibility of psychological research in general. The author considers the inherent difficulties of generating any scientific findings in this area, and concludes by discussing the signs of a hopeful trend to celebrate, rather than pathologize, people with exceptional gifts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)