Generation of a Purely Electrostatic Collisionless Shock during the Expansion of a Dense Plasma through a Rarefied Medium

A two-dimensional numerical study of the expansion of a dense plasma through a more rarefied one is reported. The electrostatic ion-acoustic shock, which is generated during the expansion, accelerates the electrons of the rarefied plasma inducing a superthermal population which reduces electron thermal anisotropy. The Weibel instability is therefore not triggered and no self-generated magnetic fields are observed, in contrast with published theoretical results dealing with plasma expansion into vacuum. The shock front develops a filamentary structure which is interpreted as the consequence of the electrostatic ion-ion instability, consistently with published analytical models and experimental results.

MeV negative ion generation from ultra-intense laser interaction with a water spray

MeV negative oxygen ions are obtained from a water spray target irradiated by high intensity (5 x 10(19) W/cm(2)) and ultrashort (50 fs) laser pulses. Generation of negative ions is ascribed to electron-capture processes that the laser-accelerated high-energy positive ion experiences when it interacts with atoms in the spray. This mechanism implies the existence of a large number of MeV neutral oxygen atoms, which is consistent with indirect experimental evidence. (C) 2011 American Institute of Physics. [doi:10.1063/1.3622664]

Attitudes towards women in politics: Gender, generation and party identification in Ireland

This article analyzes the effects of gender, generation and party support towards a greater inclusion of women in politics in the Republic of Ireland and Northern Ireland. It explores attitudes on this issue using the same question in the Irish National Election Study (INES) and the Northern Ireland Life and Times Survey (NILT). The article documents a consistent gender gap in both polities that persists across the generations, despite controls for socio-demographic factors. It also reveals an unexpected generational effect that we explain as the enduring legacy of politicization to women’s rights during the 1970s. Support among party identifiers for more women in politics follows predictable lines, yet gender and generational patterns persist. The gender gap and generational patterns found in the two polities on the island provide reason for concern among those committed to gender equality in representation.