Completeness Rules for Spin Observables in Pseudoscalar Meson Photoproduction

The number and type of measurements needed to ascertain the amplitudes for pseudoscalar meson photoproduction are analyzed in this paper. It is found that 8 carefully selected measurements can determine the four transversity amplitudes without discrete ambiguities. That number of measurements is one less than previously believed. We approach this problem in two distinct ways: (1) solving for the amplitude magnitudes and phases directly; and (2) using a bilinear helicity product formulation to map an algebra of measurements over to the well-known algebra of the $4\times 4$ Gamma matrices. It is shown that the latter method leads to an alternate proof that 8 carefully chosen experiments suffice for determining the transversity amplitudes completely. In addition, Fierz transformations of the Gamma matrices are used to develop useful linear and nonlinear relationships between the spin observables. These relationships not only help in finding complete sets of experiments, but also yield important constraints between the 16 observables for this reaction.Comment: 32 pages, no figures, LaTeX/REVTeX, submitted to Phys. Rev. C, typos correcte

Giant Magnons and Spiky Strings on S^3 with B-field

We study solutions for a rotating string on S^3 with a background NS-NS B-field and show the existence of spiky string and giant magnon as two limiting solutions. We make a connection to the sine-Gordon model via the Polyakov worldsheet action and study the effect of B-field. In particular, we find the magnon solution can be mapped to the excitation of a fractional spin chain. We conjecture a B-deformed SYM to be the gauge theory dual to this background.Comment: 22 pages, 3 figures, more references adde

Analysis of Cultural Factors in Leadership and Succession Practices in Taiwan Businesses

The purpose of this study was to examine Taiwanese leadership styles and succession practices, by reviewing current theory and practice and by conducting interviews with ten leaders of Taiwanese enterprises. The discussion with these leaders focused on their personal characteristics and behaviors related to their leadership styles, their leadership approaches, their relationship with their subordinates, the effects of their leadership styles and their succession practices. The interview data were also analyzed within the context of the literature review’s discussion on the characteristics of Chinese leadership and the traditional Chinese family enterprise. The analysis of the data indicated that the leadership styles and succession practices of Chinese business enterprises differ radically from their Western counterparts. The study showed that even though these ten Taiwanese businesses share common cultural traits, they have adopted different leadership approaches and succession practices. Finally, this research concludes that contemporary Taiwanese business enterprises could improve their leadership approaches by integrating Eastern and Western values

Streamlining the Design and Use of Array Coils for In Vivo Magnetic Resonance Imaging of Small Animals

Small-animal models such as rodents and non-human primates play an important pre-clinical role in the study of human disease, with particular application to cancer, cardiovascular, and neuroscience models. To study these animal models, magnetic resonance imaging (MRI) is advantageous as a non-invasive technique due to its versatile contrast mechanisms, large and flexible field of view, and straightforward comparison/translation to human applications. However, signal-to-noise ratio (SNR) limits the practicality of achieving the high-resolution necessary to image the smaller features of animals in an amount of time suitable for in vivo animal MRI. In human MRI, it is standard to achieve an increase in SNR through the use of array coils; however, the design, construction, and use of array coils for animal imaging remains challenging due to copper-loss related issues from small array elements and design complexities of incorporating multiple elements and associated array hardware in a limited space. In this work, a streamlined strategy for animal coil array design, construction, and use is presented and the use for multiple animal models is demonstrated. New matching network circuits, materials, assembly techniques, body-restraining systems and integrated mechanical designs are demonstrated for streamlining high-resolution MRI of both anesthetized and awake animals. The increased SNR achieved with the arrays is shown to enable high-resolution in vivo imaging of mice and common marmosets with a reduced time for experimental setup