Dancing with the Stars: Formation of the Fomalhaut triple system and its effect on the debris disks

Fomalhaut is a triple system, with all components widely separated (~1E5 au). Such widely separated binaries are thought to form during cluster dissolution, but that process is unlikely to form such a triple system. We explore an alternative scenario, where A and C form as a tighter binary from a single molecular cloud core (with semimajor axis ~1E4 au), and B is captured during cluster dispersal. We use N-body simulations augmented with the Galactic tidal forces to show that such a system naturally evolves into a Fomalhaut-like system in about half of cases, on a timescale compatible with the age of Fomalhaut. From initial non-interacting orbits, Galactic tides drive cycles in B's eccentricity that lead to a close encounter with C. After several close encounters, typically lasting tens of millions of years, one of the stars is ejected. The Fomalhaut-like case with both components at large separations is almost invariably a precursor to the ejection of one component, most commonly Fomalhaut C. By including circumstellar debris in a subset of the simulations, we also show that such an evolution usually does not disrupt the coherently eccentric debris disk around Fomalhaut A, and in some cases can even produce such a disk. We also find that the final eccentricity of the disk around A and the disk around C are correlated, which may indicate that the dynamics of the three stars stirred C's disk, explaining its unusual brightness.Comment: Accepted to MNRA

Exploratory Research on MEMS Technology for Air-Conditioning and Heat-Pumps

This report details the efforts to exploit micro-electrical-mechanical-systems (MEMS) and micro device technologies to improve control of multi-channel evaporators by reducing maldistribution among channels, and increase capacity and efficiency of current vapor-compression refrigeration chillers and heat-pumps. Besides summarizing the market potential of MEMS technology for use in evaporators and micro-heat-pumps, the report describes the accomplishments of an experimental investigation of refrigerant-side maldistribution in multi-channel plate heat exchangers (PHE's). A special test facility designed for the purpose of studying the maldistribution of refrigerant in evaporators is described in the report. The facility allows maldistribution caused by either normal superheat temperature control, or induced by the user in controlled amounts, to be measured and quantified. Four different techniques were used to detect the presence of liquid droplets in the stream of superheated vapor at the evaporator exit, an indication of maldistributed flow. They are: Helium-Neon laser, beaded thermocouple, static mixer and newly designed heated MEMS sensor. Comparison of the four techniques shows that the MEMS sensor designed and fabricated in this project has the highest potential for indicating maldistribution, manifested by entrained liquid droplets, in multi-channel evaporators. A complete set of test results in the time and frequency domain is show in graphical form in the appendices. The design, fabrication, calibration, and testing of the MEMS serpentine resistance sensor is also reported, along with a control scheme and strategy for implementing the MEMS sensor in multi-channel evaporator systems

The construction of high-performance virtual machines for dynamic languages

Dynamic languages, such as Python and Ruby, have become more widely used over the past decade. Despite this, the standard virtual machines for these languages have disappointing performance. These virtual machines are slow, not because methods for achieving better performance are unknown, but because their implementation is hard. What makes the implementation of high-performance virtual machines difficult is not that they are large pieces of software, but that there are fundamental and complex interdependencies between their components. In order to work together correctly, the interpreter, just-in-time compiler, garbage collector and library must all conform to the same precise low-level protocols. In this dissertation I describe a method for constructing virtual machines for dynamic languages, and explain how to design a virtual machine toolkit by building it around an abstract machine. The design and implementation of such a toolkit, the Glasgow Virtual Machine Toolkit, is described. The Glasgow Virtual Machine Toolkit automatically generates a just-in-time compiler, integrates precise garbage collection into the virtual machine, and automatically manages the complex inter-dependencies between all the virtual machine components. Two different virtual machines have been constructed using the GVMT. One is a minimal implementation of Scheme; which was implemented in under three weeks to demonstrate that toolkits like the GVMT can enable the easy construction of virtual machines. The second, the HotPy VM for Python, is a high-performance virtual machine; it demonstrates that a virtual machine built with a toolkit can be fast and that the use of a toolkit does not overly constrain the high-level design. Evaluation shows that HotPy outperforms the standard Python interpreter, CPython, by a large margin, and has performance on a par with PyPy, the fastest Python VM currently available

3D Bioprinted Engineered Living Materials for Continuous Organophosphorus Compound Detoxification

Engineered living materials (ELMs) are a rapidly emerging class of materials, demonstrating a wide range of functionalities, including responsive morphing, self-healing, and bio-catalysis. 3D bioprinted hydrogels have been used for the fabrication of high resolution, compartmentalised, and load-bearing structures suitable for hosting microbial metabolism, and accordingly represent an ideal environment for ELMs. The interactions between material frameworks, such as hydrogels, and encapsulated life are now beginning to be investigated.Herein, by 3D printing a hydrogel-encapsulated population of Escherichia coli, a chemically inducible, metabolically active, microbial ELM was fabricated. The material was characterised using a wide range of techniques, including fluorescence microscopy and cryogenic electron microscopy. Toxic organophosphorus compound (OPC) detoxifying capabilities were conveyed to the material through inducible expression of Agrobacterium radiobacter phosphotriesterase (arPTE). The reaction diffusion process occurring at the interface of the OPC detoxifying ELM was investigated using continuous fluorescence imaging of Coumaphos hydrolysis.. Principal component analysis was then used to uncover spatial and temporal features within this data, with relevance for future optimisation of catalytic microbial ELMstructures. To further demonstrate the applicability of this 3D printable microbial ELM, the material was incorporated into an entirely 3D printed flow reactor, demonstrating effective, cyclical detoxification of an OPC solution at high flow rate.Looking towards the future of ELM design, a novel, 3D printable, contractile-thermosensitive,double-network hydrogel was used to create thermo-responsive OPC degrading bioreactors, capable of autonomously controlling their performance

Cardiac Tissue Mapping Electrode Array to Determine Pro-Arrhythmic Tissue Substrates

Myocardial infarction (MI), commonly known as a heart attack, is the irreparable necrosis of the cardiac tissue due to sustained ischemia. MI may lead to heart failure. Despite advances in treatments, the number of patients with heart failure is increasing. Engineered heart tissue, EHT, could offer an innovative approach to treating areas of infarcted cardiac tissue. Ideally, EHT should integrate and function with the native heart without causing a higher risk for complications. The purpose of this study is to design a system to identify potentially arrhythmogenic sites in EHT. Specifically, an electrode array complete with DAQ system and data analysis program was developed to record electrical propagation and interpret conduction velocity (CV) speeds to identify areas of slow conduction. This system has the ability to analyze the activation times, calculate CV vector fields, and identify areas within the mapping window that display slow CV speeds and are considered arrhythmic-prone

Investigations of chiral effects in molecular spectroscopy

A consequence of the chiral weak interaction is that the enantiomers of a chiral molecule will differ in energy by the minute parity-violating energy difference (PVED). The enantiomers of a chiral iron complex were prepared and characterized with various spectroscopies, including x-ray photoelectron spectroscopy and x-ray diffraction. Measurements of the Mossbauer spectra show a small difference in the energy of the two enantiomers (~10-10 eV). This energy difference nears the expected order of magnitude of the parity-violating energy difference for a molecule in which the chiral center is a high Z atom. Sodium chlorate has been known to form chiral crystals from achiral aqueous solutions for over one hundred years. Typically, equal numbers of right- and left-handed crystals are produced in unstirred crystallizations. Data has been taken that show an excess of right-handed crystals are produced when crystallizations occur under the influence of a beta source. The beta particles are spin polarized due to the chiral weak interaction which is responsible for beta decay. Preliminary results indicate that the influence of positrons (which are spin polarized oppositely to beta particles) is in the opposite direction. Finally, measurements of mass resolved resonant and non-resonant multiphoton ionization of the chiral 2-butylamine entrained in a nozzle jet expansion into a linear time-of-flight mass spectrometer constructed in house were obtained using right- and left-circularly polarized laser light. In addition, ratios of ionization rates for linearly and circularly polarized light were measured

Three Rock Music Compositions and the Groups that Inspired Them: The Beatles, Yes, and Led Zeppelin, From 1967 to 1972

This thesis presents three of my popular music compositions and places these works in their historical context. The discussion spans the years 1967 to 1972, when British popular music in general and the Beatles in particular reached their zenith of creativity. In this era, the Beatles absorbed and reflected their cultural environment while exercising a strong influence on younger musicians. While social context is important to any discussion of the Beatles and their rivals, my primary focus will be the music and the process of making it. Using the Beatles and psychedelic rock in 1967 as a point of departure, I will explore two alternative genres that emerged: progressive rock and progressive blues-rock. Yes and Led Zeppelin will be emphasized as the groups that best illustrate these genres and are most relevant to my original compositions

Synthesis and Characterization of K and Eu Binary Phosphides.

The synthesis, structural characterization, and optical properties of the binary Zintl phases of α-EuP₃, β-EuP₃, EuP₂, and α-K₄P₆ are reported in this study. These crystal structures demonstrate the versatility of P fragments with dimensionality varying from 0D (P₆ rings in α-K₄P₆) to 1D chains (EuP₂) to 2D layers (both EuP₃). EuP₂ is isostructural to previously reported SrP₂ and BaP₂ compounds. The thermal stabilities of the EuP₂ and both EuP₃ phases were determined using differential scanning calorimetry (DSC), with melting temperatures of 1086 K for the diphosphide and 1143 K for the triphosphides. Diffuse reflectance spectroscopy indicated that EuP₂ is an indirect semiconductor with a direct bandgap of 1.12(5) eV and a smaller indirect one, less than 1 eV. Both EuP₃ compounds had bandgaps smaller than 1 eV