The Effect of Different Magnetospheric Structures on Predictions of Gamma-ray Pulsar Light Curves

The second pulsar catalogue of the Fermi Large Area Telescope (LAT) will contain in excess of 100 gamma-ray pulsars. The light curves (LCs) of these pulsars exhibit a variety of shapes, and also different relative phase lags with respect to their radio pulses, hinting at distinct underlying emission properties (e.g., inclination and observer angles) for the individual pulsars. Detailed geometric modelling of the radio and gamma-ray LCs may provide constraints on the B-field structure and emission geometry. We used different B-field solutions, including the static vacuum dipole and the retarded vacuum dipole, in conjunction with an existing geometric modelling code, and constructed radiation sky maps and LCs for several different pulsar parameters. Standard emission geometries were assumed, namely the two-pole caustic (TPC) and outer gap (OG) models. The sky maps and LCs of the various B-field and radiation model combinations were compared to study their effect on the resulting LCs. As an application, we compared our model LCs with Fermi LAT data for the Vela pulsar, and inferred the most probable configuration in this case, thereby constraining Vela's high-altitude magnetic structure and system geometry.Comment: 6 pages, 4 figures, conference article, appears in Proceedings of SAIP2012, the 57th Annual Conference of the South African Institute of Physics, edited by Johan Janse van Rensburg, ISBN: 978-1-77592-070-

Maternal Environments

This article explores the creation of ‘maternal environments’ in my work alongside my infants in Kyrgyzstan, Central Asia as a practice conducive to socially engaged performance towards peacemaking. Sara Ruddick defines peacemaking as ‘a way of living in which it is possible to learn and to practice nonviolent resistance and strategies of reconciliation. This description of peacemaking is a description of mothering’ (Ruddick 1990: 244). I use the term maternal environments to conceptualise the kind of human relationships and social systems that are forged through mothering as a ‘socially constructed set of activities and relationships involved in nurturing and caring for people’ (Forcey, 1994: 357). My own experiences of mothering while working as a lead consultant and applied performance facilitator with my infants and partner, James Forrester, for the Youth Theatre for Peace (YTP) project in Kyrgyzstan for the International Research and Exchanges Board (IREX) in addition to training workshops for the United Nations International Children’s Fund (UNICEF) and Foundation Tolerance International (FTI) between 2010 and 2016 are used as case studies to explore maternal environments. This article will process these deeply personal accounts of working alongside my infants to advocate for positive role-balance, institutional structural support, health-promoting lifestyles and family-friendly policies and programmes

Resistant acts in post-genocide Rwanda

Performances of justice and human rights have served as international platforms for truth-telling and nation-building both in the aftermath of apartheid in South Africa, and genocide in the case of Rwanda. There are moments of overlap between actual court proceedings, which can in their own right be deemed as a performance, and the use of theatre for dialogic negotiations between past atrocities and present juridical systems for reconstruction. 1 Within the messy context of post-conflict reconstruction, speech often falters. Articulations of identities and speech acts become disjointed between personal and collective memories and identities; but are forced into the construction of juridical speech in the case of Rwanda’s gacaca courts. This essay will analyze how micro and macro socio- political dynamics are articulated in the gacaca courts used to adjudicate crimes linked to the 1994 genocide against Tutsi during which over 1 million Tutsi and Hutu moderates were massacred. I will illustrate how these different levels of power interact with each other through social performances (Alexander, 2011) and to extend the concept of faltered speech as artistic resistance (Scott, 1990)

Performing the Nation: Theatre in Post-Genocide Rwanda

While grassroots theatre brings together perpetrators and survivors of the Rwandan genocide, government-driven campaigns can manipulate theatre for reconciliation to serve its own nationalist agenda. The Mutabaruka company use their performances in Burundi to resurrect/construct the identity of a precolonial Rwanda; the Mashirika theatre focus on reconciling the Hutu, Tutsi, and Twa

Targeted capture to assess neutral genomic variation in the narrow-leaf hopbush across a continental biodiversity refugium

The Adelaide geosyncline, a mountainous region in central southern Australia, is purported to be an important continental refugium for Mediterranean and semi-arid Australian biota, yet few population genetic studies have been conducted to test this theory. Here, we focus on a plant species distributed widely throughout the region, the narrow-leaf hopbush, Dodonaea viscosa ssp. angustissima, and examine its genetic diversity and population structure. We used a hybrid-capture target enrichment technique to selectively sequence over 700 genes from 89 individuals across 17 sampling locations. We compared 815 single nucleotide polymorphisms among individuals and populations to investigate population genetic structure. Three distinct genetic clusters were identified; a Flinders/Gammon ranges cluster, an Eastern cluster, and a Kangaroo Island cluster. Higher genetic diversity was identified in the Flinders/Gammon Ranges cluster, indicating that this area is likely to have acted as a refugium during past climate oscillations. We discuss these findings and consider the historical range dynamics of these populations. We also provide methodological considerations for population genomics studies that aim to use novel genomic approaches (such as target capture methods) on non-model systems. The application of our findings to restoration of this species across the region are also considered.Matthew J. Christmas, Ed Biffin, Martin F. Breed & Andrew J. Low

On the occurrence and motion of decametre-scale irregularities in the sub-auroral, auroral, and polar cap ionosphere

International audienceThe statistical occurrence of decametre-scale ionospheric irregularities, average line-of-sight (LOS) Doppler velocity, and Doppler spectral width in the sub-auroral, auroral, and polar cap ionosphere ( - 57°L to - 88°L) has been investigated using echoes recorded with the Tasman International Geospace Environment Radar (TIGER), a SuperDARN radar located on Bruny Island, Tasmania (147.2° E, 43.4° S geographic; - 54.6 °L). Results are shown for routine soundings made on the magnetic meridian beam 4 and the near zonal beam 15 during the sunspot maximum interval December 1999 to November 2000. Most echoes were observed in the nightside ionosphere, typically via 1.5-hop propagation near dusk and then via 0.5-hop propagation during pre-midnight to dawn. Peak occurrence rates on beam 4 were often > 60% near magnetic midnight and ~ - 70 °L. They increased and shifted equatorward and toward pre-midnight with increasing Kp (i.e. Bz southward). The occurrence rates remained very high for Kp > 4, de-spite enhanced D-region absorption due to particle precipitation. Average occurrence rates on beam 4 exhibited a relatively weak seasonal variation, consistent with known longitudinal variations in auroral zone magnetic activity (Basu, 1975). The average echo power was greatest between 23 and 07 MLT. Two populations of echoes were identified on both beams, those with low spectral width and a mode value of ~ 9 ms-1 (bin size of 2 ms-1) concentrated in the auroral and sub-auroral ionosphere (population A), and those with high spectral width and a mode value of ~ 70 ms-1 concentrated in the polar cap ionosphere (population B). The occurrence of population A echoes maximised post-midnight because of TIGER's lower latitude, but the subset of the population A echoes observed near dusk had characteristics reminiscent of "dusk scatter" (Ruohoniemi et al., 1988). There was a dusk "bite out" of large spectral widths between ~ 15 and 21 MLT and poleward of - 67 °L, and a pre-dawn enhancement of large spectral widths between ~ 03 and 07 MLT, centred on ~ - 61 °L. The average LOS Doppler velocities revealed that frequent westward jets of plasma flow occurred equatorward of, but overlapping, the diffuse auroral oval in the pre-midnight sector