A Most Fateful Encounter: How Scipio Africanus Defeated Hannibal Barca at the Battle of Zama

This thesis addresses the question of why Hannibal Barca suffered such a decisive defeat at the hands of Scipio Africanus in the Battle of Zama. I begin by conducting a thorough analysis of the two ancient sources that have provided us with the bulk of what is known about the battle and the events leading up to it. My analysis of them primarily concerns itself with determining how objective and trustworthy these accounts are, and as such how much faith can be placed in the details they provide. Using these sources, I then proceed to examine the events leading up to the Battle of Zama itself, specifically Scipio\u27s campaign in North Africa and how his strategic decisions and maneuvers ultimately forced Hannibal to return to North Africa and confront him. I then conduct an analysis of the battle itself and each general\u27s tactical performance. Before drawing my own conclusions as to why Hannibal lost, I review the texts of scholars who have also written on the subject to determine what they believe were the factors responsible for Hannibal\u27s defeat, categorizing them into two major schools of thought. Finally, I choose one side and then add my own contributions as to why Scipio Africanus triumphed in the end

Optical Classification of Gamma-Ray Bursts in the Swift Era

We propose a new method for the classification of optically dark gamma-ray bursts (GRBs), based on the X-ray and optical-to-X-ray spectral indices of GRB afterglows, and utilizing the spectral capabilities of Swift. This method depends less on model assumptions than previous methods, and can be used as a quick diagnostic tool to identify optically sub-luminous bursts. With this method we can also find GRBs that are extremely bright at optical wavelengths. We show that the previously suggested correlation between the optical darkness and the X-ray/gamma-ray brightness is merely an observational selection effect.Comment: 6 pages, 3 figures; accepted for publication in Ap

GRB 030329: 3 years of radio afterglow monitoring

Radio observations of gamma-ray burst (GRB) afterglows are essential for our understanding of the physics of relativistic blast waves, as they enable us to follow the evolution of GRB explosions much longer than the afterglows in any other wave band. We have performed a three-year monitoring campaign of GRB 030329 with the Westerbork Synthesis Radio Telescopes (WSRT) and the Giant Metrewave Radio Telescope (GMRT). Our observations, combined with observations at other wavelengths, have allowed us to determine the GRB blast wave physical parameters, such as the total burst energy and the ambient medium density, as well as investigate the jet nature of the relativistic outflow. Further, by modeling the late-time radio light curve of GRB 030329, we predict that the Low-Frequency Array (LOFAR, 30-240 MHz) will be able to observe afterglows of similar GRBs, and constrain the physics of the blast wave during its non-relativistic phase.Comment: 5 pages, 2 figures, Phil. Trans. R. Soc. A, vol.365, p.1241, proceedings of the Royal Society Scientific Discussion Meeting, London, September 200

Capacity estimation and verification of quantum channels with arbitrarily correlated errors

© 2017 The Author(s). The central figure of merit for quantum memories and quantum communication devices is their capacity to store and transmit quantum information. Here, we present a protocol that estimates a lower bound on a channel's quantum capacity, even when there are arbitrarily correlated errors. One application of these protocols is to test the performance of quantum repeaters for transmitting quantum information. Our protocol is easy to implement and comes in two versions. The first estimates the one-shot quantum capacity by preparing and measuring in two different bases, where all involved qubits are used as test qubits. The second verifies on-the-fly that a channel's one-shot quantum capacity exceeds a minimal tolerated value while storing or communicating data. We discuss the performance using simple examples, such as the dephasing channel for which our method is asymptotically optimal. Finally, we apply our method to a superconducting qubit in experiment

SCUBA Observations of the Host Galaxies of Gamma-Ray Bursts

In recent years, a population of galaxies with huge infrared luminosities and dust masses has been discovered in the submillimetre. Observations suggest that the AGN contribution to the luminosities of these submillimetre-selected galaxies is low; instead their luminosities are thought to be mainly due to strong episodes of star formation following merger events. Our current understanding of GRBs as the endpoints in the life of massive stars suggest that they will be located in such galaxies.We have observed a sample of well-located GRB host galaxies in the submillimetre. Comparing the results with the general submillimetre-selected galaxy population, we find that at low fluxes (S850 ≤ 4 mJy), the two agree well. However, there is a lack of bright GRB hosts in the submillimetre. This finding is reinforced when the results of other groups are included. Possible explanations are discussed. These results help us assess the roles of both GRB host galaxies and submillimetre-selected galaxies in the evolution of the Universe

An Experimental Microarchitecture for a Superconducting Quantum Processor

Quantum computers promise to solve certain problems that are intractable for classical computers, such as factoring large numbers and simulating quantum systems. To date, research in quantum computer engineering has focused primarily at opposite ends of the required system stack: devising high-level programming languages and compilers to describe and optimize quantum algorithms, and building reliable low-level quantum hardware. Relatively little attention has been given to using the compiler output to fully control the operations on experimental quantum processors. Bridging this gap, we propose and build a prototype of a flexible control microarchitecture supporting quantum-classical mixed code for a superconducting quantum processor. The microarchitecture is based on three core elements: (i) a codeword-based event control scheme, (ii) queue-based precise event timing control, and (iii) a flexible multilevel instruction decoding mechanism for control. We design a set of quantum microinstructions that allows flexible control of quantum operations with precise timing. We demonstrate the microarchitecture and microinstruction set by performing a standard gate-characterization experiment on a transmon qubit.Comment: 13 pages including reference. 9 figure