Developments in GRworkbench

The software tool GRworkbench is an ongoing project in visual, numerical General Relativity at The Australian National University. Recently, GRworkbench has been significantly extended to facilitate numerical experimentation in analytically-defined space-times. The numerical differential geometric engine has been rewritten using functional programming techniques, enabling objects which are normally defined as functions in the formalism of differential geometry and General Relativity to be directly represented as function variables in the C++ code of GRworkbench. The new functional differential geometric engine allows for more accurate and efficient visualisation of objects in space-times and makes new, efficient computational techniques available. Motivated by the desire to investigate a recent scientific claim using GRworkbench, new tools for numerical experimentation have been implemented, allowing for the simulation of complex physical situations.Comment: 14 pages. To appear A. Moylan, S.M. Scott and A.C. Searle, Developments in GRworkbench. Proceedings of the Tenth Marcel Grossmann Meeting on General Relativity, editors M. Novello, S. Perez-Bergliaffa and R. Ruffini. Singapore: World Scientific 200

Network sensitivity to geographical configuration

Gravitational wave astronomy will require the coordinated analysis of data from the global network of gravitational wave observatories. Questions of how to optimally configure the global network arise in this context. We have elsewhere proposed a formalism which is employed here to compare different configurations of the network, using both the coincident network analysis method and the coherent network analysis method. We have constructed a network model to compute a figure-of-merit based on the detection rate for a population of standard-candle binary inspirals. We find that this measure of network quality is very sensitive to the geographic location of component detectors under a coincident network analysis, but comparatively insensitive under a coherent network analysis.Comment: 7 pages, 4 figures, accepted for proceedings of the 4th Edoardo Amaldi conference, incorporated referees' suggestions and corrected diagra

Property-based welfare and the search for generational equality

In many countries, the demographic shift towards an ageing population is occurring against a backdrop of welfare state restructuring. The paradigm of asset-based welfare may become increasingly central to these developments as individualised welfare is touted as part of the response to the challenge of funding the care of an ageing population. This article focuses on the framing of housing wealth as a form of asset-based welfare in the UK context. We consider the strengths and weaknesses of housing as a form of asset-based welfare, both in terms of equity between generations and equality within them. We argue that housing market gains have presented many homeowners with significant, and arguably unearned, wealth and that policy-makers could reasonably expect that some of these assets be utilised to meet welfare needs in later life. However, the suitability of asset-based welfare as a panacea to the fiscal costs of an ageing population and welfare state retraction is limited by a number of potential practical and ethical concerns

Targeted search for continuous gravitational waves: Bayesian versus maximum-likelihood statistics

We investigate the Bayesian framework for detection of continuous gravitational waves (GWs) in the context of targeted searches, where the phase evolution of the GW signal is assumed to be known, while the four amplitude parameters are unknown. We show that the orthodox maximum-likelihood statistic (known as F-statistic) can be rediscovered as a Bayes factor with an unphysical prior in amplitude parameter space. We introduce an alternative detection statistic ("B-statistic") using the Bayes factor with a more natural amplitude prior, namely an isotropic probability distribution for the orientation of GW sources. Monte-Carlo simulations of targeted searches show that the resulting Bayesian B-statistic is more powerful in the Neyman-Pearson sense (i.e. has a higher expected detection probability at equal false-alarm probability) than the frequentist F-statistic.Comment: 12 pages, presented at GWDAW13, to appear in CQ

Host Community Voices and Community Experiences: Tanzanian Perspectives on a Teacher Education International Service-Learning Project

Teacher education programs are increasingly integrating aspects of international service-learning (ISL) into student experience. While studies about teacher-candidate experiences are published, less is known about the effects of these ISL initiatives on the host communities. There is a need to hear from and integrate host community voices into all dimensions of the ISL experiences. We honor the voices of ISL host participants by turning our attention to those involved in an ongoing ISL project in Tanzania. Our analysis is grounded in our experiences as ISL practitioners and teacher educators. We utilize the concepts of Freire and Dewey to provide an understanding of ISL in teacher education that emphasizes how dialogue with host participants increases understanding of local contexts and promotes reciprocity as a form of learning from one another. This study concludes with the implications, both negative and positive, associated with integrating ISL into teacher education programs

Deciphering the epitranscriptome: a green perspective

The advent of high-throughput sequencing technologies coupled with new detection methods of RNA modifications has enabled investigation of a new layer of gene regulation - the epitranscriptome. With over 100 known RNA modifications, understanding the repertoire of RNA modifications is a huge undertaking. This review summarizes what is known about RNA modifications with an emphasis on discoveries in plants. RNA ribose modifications, base methylations and pseudouridylation are required for normal development in Arabidopsis, as mutations in the enzymes modifying them have diverse effects on plant development and stress responses. These modifications can regulate RNA structure, turnover and translation. Transfer RNA and ribosomal RNA modifications have been mapped extensively and their functions investigated in many organisms, including plants. Recent work exploring the locations, functions and targeting of N6 -methyladenosine (m6 A), 5-methylcytosine (m5 C), pseudouridine (Ψ), and additional modifications in mRNAs and ncRNAs are highlighted, as well as those previously known on tRNAs and rRNAs. Many questions remain as to the exact mechanisms of targeting and functions of specific modified sites and whether these modifications have distinct functions in the different classes of RNAs.Alice Burgess, Rakesh David, Iain Robert Searl