Double-resonant fast particle-wave interaction

In future fusion devices fast particles must be well confined in order to transfer their energy to the background plasma. Magnetohydrodynamic instabilities like Toroidal Alfv\'en Eigenmodes or core-localized modes such as Beta Induced Alfv\'en Eigenmodes and Reversed Shear Alfv\'en Eigenmodes, both driven by fast particles, can lead to significant losses. This is observed in many ASDEX Upgrade discharges. The present study applies the drift-kinetic HAGIS code with the aim of understanding the underlying resonance mechanisms, especially in the presence of multiple modes with different frequencies. Of particular interest is the resonant interaction of particles simultaneously with two different modes, referred to as 'double-resonance'. Various mode overlapping scenarios with different q profiles are considered. It is found that, depending on the radial mode distance, double-resonance is able to enhance growth rates as well as mode amplitudes significantly. Surprisingly, no radial mode overlap is necessary for this effect. Quite the contrary is found: small radial mode distances can lead to strong nonlinear mode stabilization of a linearly dominant mode.Comment: 12 pages, 11 figures; Nuclear Fusion 52 (2012

Firm Size and the Information Content of Over-the-Counter Common Stock Offerings

We examine the announcement period of stock returns for 179 over-the-counter (OTC) firms that issue common stock to reduce nonconvertible debt. We find that small OTC firms experience returns that are significantly more negative than large OTC firms. Regression tests reveal that firm size is a significant factor in accounting for stock returns. Other tests establish as firm size a dominant effect. Our support for a firm size effect is consistent with a differential information effect given that firm size is positively related to the amount of information available about firms

Alfvén Eigenmodes in shear reversed plasmas

Experiments on JT-60U and JET have shown that plasma configurations with shear reversal are prone to the excitation of unusual Alfvén eigenmodes by energetic particles. These modes emerge outside the TAE frequency gap, where one might expect them to be strongly damped. The modes often appear in bunches and they exhibit a quasi-periodic pattern of predominantly upward frequency sweeping (Alfvén Cascades) as the safety factor q changes in time. This work presents a theory that explains the key features of the observed unusual modes including their connection to TAE’s as well as the modifications of TAE’s themselves near the shear reversal point. The developed theory has been incorporated into a reduced numerical model and verified with full geometry codes. JET experimental data on Alfvén spectroscopy have been simulated to infer the mode numbers and the evolution of qmin in the discharge. This analysis confirms the values of q that characterize the internal transport barrier triggering in reversed shear plasmas

Diasporic Dreams, Middle Class Moralities and Migrant Domestic Workers among Muslim Filipinos in Saudi Arabia

This paper is about middle-class Muslim Filipinos in Saudi Arabia and their discourses about and relationships with migrant domestic workers. Saudi Arabia is not simply a temporary stopping point to a better future elsewhere, but is also a place where the middle-class aspirations of Muslim Filipinos may be realised and where their religious affiliations as Muslims may be seen as enhancing rather than detracting from those dreams and imaginings. As part of a large and diverse diasporic community, middle-class Filipinos routinely interact and socialise with working-class Filipinos. They often provide succour and support for their compatriots who labour under difficult and legally unprotected conditions. Some employ migrant domestic workers in their homes, many of whom are irregular or takas (escapees). At the same time, they reproduce and reinforce many of the gendered stereotypes of domestic workers that often suggest moral failings of one sort or another. The simultaneous embracing of and distancing from domestic workers reflects the anxieties of those, particularly women, whose tenuous hold of middle-class status is accomplished through, but also put at risk by, the precariousness of their sojourns abroad in the Kingdom