Bounding the mass of the graviton using binary pulsar observations

The close agreement between the predictions of dynamical general relativity for the radiated power of a compact binary system and the observed orbital decay of the binary pulsars PSR B1913+16 and PSR B1534+12 allows us to bound the graviton mass to be less than 7.6 x 10^{-20} eV with 90% confidence. This bound is the first to be obtained from dynamic, as opposed to static-field, relativity. The resulting limit on the graviton mass is within two orders of magnitude of that from solar system measurements, and can be expected to improve with further observations.Comment: 16 pages, 1 figure. Added appendix on other choices for mass ter

The Search for Antibiotic Leads: Targeting Pantothenate Kinase in Pseudomonas aeruginosa

Master's Thesis in Biomedical SciencesBMED395MAMD-MEDB

Swift Pointing and Gravitational-Wave Bursts from Gamma-Ray Burst Events

The currently accepted model for gamma-ray burst phenomena involves the violent formation of a rapidly rotating solar-mass black hole. Gravitational waves should be associated with the black-hole formation, and their detection would permit this model to be tested. Even upper limits on the gravitational-wave strength associated with gamma-ray bursts could constrain the gamma-ray burst model. This requires joint observations of gamma-ray burst events with gravitational and gamma-ray detectors. Here we examine how the quality of an upper limit on the gravitational-wave strength associated with gamma-ray bursts depends on the relative orientation of the gamma-ray-burst and gravitational-wave detectors, and apply our results to the particular case of the Swift Burst-Alert Telescope (BAT) and the LIGO gravitational-wave detectors. A result of this investigation is a science-based ``figure of merit'' that can be used, together with other mission constraints, to optimize the pointing of the Swift telescope for the detection of gravitational waves associated with gamma-ray bursts.Comment: iop style, 1 figure, 6 pages, presented at GWDAW 200

Building capacity for policy analysis

This paper attempts to examine the concept and scope of policy analysis and to distill the lessons of experience in building the capacity for policy analysis in a number of developing countries over the past three decades. It concludes that strategies for developing indigenous capabilities for policy analysis will vary from country to country. In countries where non-government clientele and sources of support are limited but government is interested, the initial focus should be on strengthening government capability. Countries where there is demand for policy analysis in both the government and private sector may be ripe for arm's length centers for policy analysis. If such centers are not appropriate, private sector associations could help set up policy analysis units. In countries where the private sector is weak, academic institutions with close links to government may help create some local capability.Poverty Assessment,ICT Policy and Strategies,Geographical Information Systems,Inequality,Achieving Shared Growth

Use of capillary electrophoresis as a method development tool for classical gel electrophoresis

Capillary electrophoresis (CE) was used to optimize the buffer pH, ionic strength and sulfated cyclodextrin concentrations for enantiomeric separation of piperoxan. These enantioseparation conditions were then applied to a classical gel electrophoresis system. Binding constants of the sulfated beta-cyclodextrin–piperoxan couple were approximated using CE and the effects of organic solvents on the system were also investigated

Determination of high temperature strains using a PC based vision system

With the widespread availability of video digitizers and cheap personal computers, the use of computer vision as an experimental tool is becoming common place. These systems are being used to make a wide variety of measurements that range from simple surface characterization to velocity profiles. The Sub-Pixel Digital Image Correlation technique has been developed to measure full field displacement and gradients of the surface of an object subjected to a driving force. The technique has shown its utility by measuring the deformation and movement of objects that range from simple translation to fluid velocity profiles to crack tip deformation of solid rocket fuel. This technique has recently been improved and used to measure the surface displacement field of an object at high temperature. The development of a PC based Sub-Pixel Digital Image Correlation system has yielded an accurate and easy to use system for measuring surface displacements and gradients. Experiments have been performed to show the system is viable for measuring thermal strain

Swift Pointing and the Association Between Gamma-Ray Bursts and Gravitational-Wave Bursts

The currently accepted model for gamma-ray burst phenomena involves the violent formation of a rapidly rotating solar mass black hole. Gravitational waves should be associated with the black-hole formation, and their detection would permit this model to be tested, the black hole progenitor (e.g., coalescing binary or collapsing stellar core) identified, and the origin of the gamma rays (within the expanding relativistic fireball or at the point of impact on the interstellar medium) located. Even upper limits on the gravitational-wave strength associated with gamma-ray bursts could constrain the gamma-ray burst model. To do any of these requires joint observations of gamma-ray burst events with gravitational and gamma-ray detectors. Here we examine how the quality of an upper limit on the gravitational-wave strength associated with gamma-ray burst observations depends on the relative orientation of the gamma-ray-burst and gravitational-wave detectors, and apply our results to the particular case of the Swift Burst-Alert Telescope (BAT) and the LIGO gravitational-wave detectors. A result of this investigation is a science-based ``figure of merit'' that can be used, together with other mission constraints, to optimize the pointing of the Swift telescope for the detection of gravitational waves associated with gamma-ray bursts.Comment: aastex, 14 pages, 2 figure

Between the crowd and the band: Performance experience, creative practice, and wellbeing for professional touring musicians

In some musical genres, professional performers play live shows many times a week. Arduous touring schedules bring encounters with wildly diverse audiences across many different performance ecologies. We investigate the kinds of creativity involved in such repeated live performance, kinds of creativity that are quite unlike songwriting and recording, and examine the central factors that influence musicians’ wellbeing over the course of a tour. The perspective of the professional musician has been underrepresented in research on relations between music and wellbeing, with little attention given to the experience of touring. In this case study, we investigate influences on positive and negative performance experiences for the four professional musicians of Australian pop/rock band Cloud Control. Geeves conducted intensive cognitive ethnographic fieldwork with Cloud Control members over a two-week national Australian tour for their second album, Dream Cave (2013). Adapting a Grounded Theory approach to data analysis, we found the level of wellbeing musicians reported and displayed on tour to be intimately linked to their creative performance experiences through the two emergent, overarching and interdependent themes of Performance Headspace (PH) and Connection with Audience (CA). We explore these themes in detail and provide examples to demonstrate how PH and CA can feed off each other in virtuous ways that positively shape musicians’ wellbeing, or loop in vicious ways that negatively shape musicians’ wellbeing. We argue that their creative practice, in thus re-enacting musical performance afresh in each venue’s distinctive setting, emerges within unique constraints each night, and is in a sense a co-creation of the crowd and the band

Learning from Monte Carlo Rollouts with Opponent Models for Playing Tron

This paper describes a novel reinforcement learning system for learning to play the game of Tron. The system combines Q-learning, multi-layer perceptrons, vision grids, opponent modelling, and Monte Carlo rollouts in a novel way. By learning an opponent model, Monte Carlo rollouts can be effectively applied to generate state trajectories for all possible actions from which improved action estimates can be computed. This allows to extend experience replay by making it possible to update the state-action values of all actions in a given game state simultaneously. The results show that the use of experience replay that updates the Q-values of all actions simultaneously strongly outperforms the conventional experience replay that only updates the Q-value of the performed action. The results also show that using short or long rollout horizons during training lead to similar good performances against two fixed opponents