Wendy Wan

© 2015 authors. Published by the American Physical Society.We present a design of superconducting magnets, optimized for application in a gantry for proton therapy. We have introduced a new magnet design concept, called an alternating-gradient canted cosine theta concept, which is compatible with an achromatic layout. This layout allows a large momentum acceptance. The 15 cm radius of the bore aperture enables the application of pencil beam scanning in front of the SC-magnet. The optical and dynamic performance of a gantry based on these magnets has been analyzed using the fields derived from the actual windings of the AG-CCT combined with the full equations of motion. The results show that with appropriate higher order correction, a large 3D volume can be rapidly scanned with little beam shape distortion. A very big advantage is that all this can be done while keeping the AG-CCT fields fixed. This reduces the need for fast field ramping of the superconducting magnets between the successive beam energies used for the scanning in depth and it is important for medical application since this reduces the technical risk associated with fast field changes in superconducting magnets. For proton gantries the corresponding superconducting magnet system holds promise of dramatic reduction in weight. For heavier ion gantries there may furthermore be a significant reduction in size.

© 2015 Biophysical Society. Prions are proteins that adopt self-propagating aberrant folds. The self-propagating properties of prions are a direct consequence of their distinct structures, making the understanding of these structures and their biophysical interactions fundamental to understanding prions and their related diseases. The insolubility and inherent disorder of prions have made their structures difficult to study, particularly in the case of the infectious form of the mammalian prion protein PrP. Many investigators have therefore preferred to work with peptide fragments of PrP, suggesting that these peptides might serve as structural and functional models for biologically active prions. We have used x-ray fiber diffraction to compare a series of different-sized fragments of PrP, to determine the structural commonalities among the fragments and the biologically active, self-propagating prions. Although all of the peptides studied adopted amyloid conformations, only the larger fragments demonstrated a degree of structural complexity approaching that of PrP. Even these larger fragments did not adopt the prion structure itself with detailed fidelity, and in some cases their structures were radically different from that of pathogenic PrPSc.

On one hand, Chinese consumers are well known for conspicuous consumption and the adoption of luxury products and named brands. On the other hand, they also have a bad reputation for buying counterfeit products. Their simultaneous preferences for two contrasting types of product present a paradox that has not been addressed in the literature. This study attempts to present an explanation of this paradox by examining the effects of traditional Chinese cultural values and consumer values on consumers’ deontological judgment of pirated CDs and the amount of social benefits they perceive they gain from them. We interviewed 300 Hong Kong Chinese consumers, and found that face consciousness increased materialism and risk aversion, thereby producing a favorable deontological judgment of pirated CDs. Face consciousness also has a direct effect on the amount of social benefits perceived in pirated CDs. Both favorable deontological judgment and perceived social benefits contributed to a strong intention to buy pirated CDs. The results are discussed in a cultural perspective.