Possible Optical/Infrared Jet Emission in 4U 1543-47

We have taken optical and infrared observations during the 2002 outburst of the soft X-ray transient, 4U 1543-47. A secondary maximum occurs in the lightcurves during the outburst decline. This feature is much stronger at infrared wavelengths than optical. We have applied single blackbody, multicolor blackbody and broken-power law models to the optical/infrared spectral energy distribution of the secondary maximum and find that the broken power-law provides the best fit. We therefore conclude that the secondary maximum emission originates from a jet. We also show the most recent lightcurves of the 2002/2003 outburst of GX 339-4 in which a secondary maximum appears. This leads us to the conclusion that secondary maxima may be a common occurrence in soft X-ray transients during outburst decline which appear after the object transitions into the low-hard state. Infrared observations of such phenomena will give reliable triggers for multiwavelength observations, allowing us to greatly improve our knowledge of jet formation and behavior, and how this relates to the accretion geometry.Comment: 4 pages, to appear in ``X-Ray Timing 2003: Rossi and Beyond'' conference proceedings, references now visibl

Does young motherhood put the family ‘in crisis’? An ethnographic investigation into the impact of young motherhood on intergenerational relations within families

Young motherhood is often framed as a ‘social problem’ by policy, society and media, posing a threat to established ideas about ‘the family’. This framing focuses on young mothers as individual (stereo)types, and does not capture the intergenerational relationships that provide an important context for young motherhood, forming a significant source of tension and/or support. This thesis contributes to an underresearched area, by focussing on relationships between young mothers and their own mothers, in the context of the wider social and moral circumstances of families, reasons behind young motherhood, and the role played by stigma in the construction of young mothers’ identities. This is a qualitative study based on focus group narratives by women who had a child under the age of 21, and their mothers, across the Isle of Thanet. The findings from the MA thesis suggest that intergenerational relationships evolved prior to and following pregnancy, with the child becoming the locus for reimagining life courses. ‘Family’ was reconstructed as ‘new nuclear’, moving away from traditional family constructs, with intimate daily practices crucial to its recasting. Young motherhood is thus considered as an individual experience, where a child can be the reason as a turning point for young women, which can be enhanced by a strong intergenerational support network. The study highlights the importance of family support networks, and contributes to existing research challenging assumptions and young motherhood outcomes and experiences

A lattice spring model of heterogeneous materials with plasticity

A three-dimensional lattice spring model of a heterogeneous material is presented. For small deformations, the model is shown to recover the governing equations for an isotropic elastic medium. The model gives reasonable agreement with theoretical predictions for the elastic fields generated by a spherical inclusion, although for small particle sizes the discretization of the underlying lattice causes some departures from the predicted values. Plasticity is introduced by decreasing the elastic moduli locally whilst maintaining stress continuity. Results are presented for a spherical inclusion in a plastic matrix and are found to be in good agreement with the predictions of Wilner (1988 J. Mech. Phys. Solids 36 141-65).</p

A novel method of combining blood oxygenation and blood flow sensitive magnetic resonance imaging techniques to measure the cerebral blood flow and oxygen metabolism responses to an unknown neural stimulus.

Simultaneous implementation of magnetic resonance imaging methods for Arterial Spin Labeling (ASL) and Blood Oxygenation Level Dependent (BOLD) imaging makes it possible to quantitatively measure the changes in cerebral blood flow (CBF) and cerebral oxygen metabolism (CMRO(2)) that occur in response to neural stimuli. To date, however, the range of neural stimuli amenable to quantitative analysis is limited to those that may be presented in a simple block or event related design such that measurements may be repeated and averaged to improve precision. Here we examined the feasibility of using the relationship between cerebral blood flow and the BOLD signal to improve dynamic estimates of blood flow fluctuations as well as to estimate metabolic-hemodynamic coupling under conditions where a stimulus pattern is unknown. We found that by combining the information contained in simultaneously acquired BOLD and ASL signals through a method we term BOLD Constrained Perfusion (BCP) estimation, we could significantly improve the precision of our estimates of the hemodynamic response to a visual stimulus and, under the conditions of a calibrated BOLD experiment, accurately determine the ratio of the oxygen metabolic response to the hemodynamic response. Importantly we were able to accomplish this without utilizing a priori knowledge of the temporal nature of the neural stimulus, suggesting that BOLD Constrained Perfusion estimation may make it feasible to quantitatively study the cerebral metabolic and hemodynamic responses to more natural stimuli that cannot be easily repeated or averaged

Understanding the fidelity effect when evaluating games with children

There have been a number of studies that have compared evaluation results from prototypes of different fidelities but very few of these are with children. This paper reports a comparative study of three prototypes ranging from low fidelity to high fidelity within the context of mobile games, using a between subject design with 37 participants aged 7 to 9. The children played a matching game on either an iPad, a paper prototype using screen shots of the actual game or a sketched version. Observational data was captured to establish the usability problems, and two tools from the Fun Toolkit were used to measure user experience. The results showed that there was little difference for user experience between the three prototypes and very few usability problems were unique to a specific prototype. The contribution of this paper is that children using low-fidelity prototypes can effectively evaluate games of this genre and style