Quiescent X-Ray/Optical Counterparts of the Black Hole Transient H 1705-250

We report the result of a new Chandra observation of the black hole X-ray transient H 1705-250 in quiescence. H 1705-250 was barely detected in the new 50 ks Chandra observation. With 5 detected counts, we estimate the source quiescent luminosity to be Lx~9.1e30 erg/s in the 0.5-10 keV band (adopting a distance of 8.6 kpc). This value is in line with the quiescent luminosities found among other black hole X-ray binaries with similar orbital periods. By using images taken with the Faulkes Telescope North, we derive a refined position of H 1705-250. We also present the long-term lightcurve of the optical counterpart from 2006 to 2012, and show evidence for variability in quiescence.Comment: 5 pages, 2 figures; Accepted for publication in MNRA

Mary Doe’s Destiny: How The United States Has Banned Human Embryonic Stem Cell Research In The Absence Of A Direct Prohibition

Mary Doe is a human embryo preserved in liquid nitrogen, in an unnamed in vitro fertilization clinic. Mary Doe’s name was given by an organization dedicated to advocating for equal humanity and personhood of pre-born children, including “children in vitro.” In response to President Clinton’s policy favoring embryonic stem cell [hereinafter ES- cell] research, the organization filed suit on behalf of Mary Doe, and all other frozen human embryos similarly situated, seeking a permanent injunction against any and all plans to undertake human ES-cell experimentation

Non-Commutativity, Teleology and GRB Time Delay

We propose a model in which an energy-dependent time delay of a photon originates from space-time non-commutativity, the time delay is due to a noncommutative coupling between dilaton and photon. We predict that in our model, high energy photons with different momenta can either be delayed or superluminal, this may be related to a possible time delay reported by the Fermi LAT and Fermi GBM Collaborations.Comment: 8 pages, 1 figure, typo revised, contents and reference adde

Accelerating Stochastic Sequential Quadratic Programming for Equality Constrained Optimization using Predictive Variance Reduction

In this paper, we propose a stochastic method for solving equality constrained optimization problems that utilizes predictive variance reduction. Specifically, we develop a method based on the sequential quadratic programming paradigm that employs variance reduction in the gradient approximations. Under reasonable assumptions, we prove that a measure of first-order stationarity evaluated at the iterates generated by our proposed algorithm converges to zero in expectation from arbitrary starting points, for both constant and adaptive step size strategies. Finally, we demonstrate the practical performance of our proposed algorithm on constrained binary classification problems that arise in machine learning.Comment: 41 pages, 5 figures, 4 table

Fast Simulation and a Search for Four-top-quark Production with the ATLAS Experiment

The Standard Model of particle physics is one of the most successful theories in physics. However there is still a range of natural phenomena that it is unable to explain. This thesis presents a measurement of Standard Model production of four top quarks, a rare process that is sensitive to influences from potential beyond Standard Model processes, using data from the ATLAS experiment at CERN's Large Hadron Collider (LHC). This thesis also documents a fast simulation software package that was developed for the ATLAS Fast Tracker system, which will be instrumental in adapting to the coming High-Luminosity LHC era.Thesis (MPhil) -- University of Adelaide, School of Physical Sciences, 202