The distributions of stellar remnants in disk galaxies

This thesis presents an account of work on the distribution of supernova remnants in galaxies. It consists of 3 parts, the identification of runaway stars in galaxies and then the modelling of the expected distribution of these stars around a galaxy and their expected dispersion over time. The first part of the thesis is a thorough survey of supernovae in the Asiago database and identification of those that are located away from the plane of the galaxy. He investigated their height and radial distribution relative to the galaxy and confirmed previous work with a larger sample size. The rest of the work involved computer modelling of the distribution of star remnants and runaway objects in galaxies and the time evolution of their distribution. It concluded that the radial distribution of remnants would be similar to thar of the stars in the galaxy but their height distribution would be larger indicating sufficient velocity to escape from the disk. Despite their larger velocity relative to surrounding stars, the time evolution of the HMXB spatial distribution shows a similar pattern to that of the stars in the galaxy

Resonant Orbits and the High Velocity Peaks Towards the Bulge

We extract the resonant orbits from an N-body bar that is a good representation of the Milky Way, using the method recently introduced by Molloy et al. (2015). By decomposing the bar into its constituent orbit families, we show that they are intimately connected to the boxy-peanut shape of the density. We highlight the imprint due solely to resonant orbits on the kinematic landscape towards the Galactic centre. The resonant orbits are shown to have distinct kinematic features and may be used to explain the cold velocity peak seen in the APOGEE commissioning data (Nidever at al., 2012). We show that high velocity peaks are a natural consequence of the motions of stars in the 2:1 orbit family and that stars on other higher order resonances can contribute to the peaks. The locations of the peaks vary with bar angle and, with the tacit assumption that the observed peaks are due to the 2:1 family, we find that the locations of the high velocity peaks correspond to bar angles in the range 10 < theta_bar < 25 (deg). However, some important questions about the nature of the peaks remain, such as their apparent absence in other surveys of the Bulge and the deviations from symmetry between equivalent fields in the north and south. We show that the absence of a peak in surveys at higher latitudes is likely due to the combination of a less prominent peak and a lower number density of bar supporting orbits at these latitudes.Comment: 7 Figures, 1 Table, Now includes figures & discussion of higher order resonances, Minor revisions to text throughout, Conclusions unchange

Resonant Clumping and Substructure in Galactic Discs

We describe a method to extract resonant orbits from N-body simulations exploiting the fact that they close in a frame rotating with a constant pattern speed. Our method is applied to the N-body simulation of the Milky Way by Shen et al. (2010). This simulation hosts a massive bar, which drives strong resonances and persistent angular momentum exchange. Resonant orbits are found throughout the disc, both close to the bar itself and out to the very edges of the disc. Using Fourier spectrograms, we demonstrate that the bar is driving kinematic substructure even in the very outer parts of the disc. We identify two major orbit families in the outskirts of the disc that make significant contributions to the kinematic landscape, namely the m:l = 3:-2 and 1:-1 families resonating with the pattern speed of the bar. A mechanism is described that produces bimodal distributions of Galactocentric radial velocities at selected azimuths in the outer disc. It occurs as a result of the temporal coherence of particles on the 3:-2 resonant orbits, which causes them to arrive simultaneously at pericentre or apocentre. This resonant clumping, due to the in-phase motion of the particles through their epicycle, leads to both inward and outward moving groups which belong to the same orbital family and consequently produce bimodal radial velocity distributions. This is a possible explanation of the bimodal velocity distributions observed towards the Galactic anti-Centre by Liu et al. (2012). Another consequence is that transient overdensities appear and dissipate (in a symmetric fashion) on timescales equal to the their epicyclic period resulting in a periodic pulsing of the disc's surface density.Comment: 11 Figures, 1 Table. Accepted for publication in ApJ. Version 2 reflects minor changes to the text. Animation referenced in Figure 7 is available at http://hubble.shao.ac.cn/~shen/resonantclumping/DensMovie.mp

A framework for enhancing process understanding using multivariate tools on commercial batch process data

EngD ThesisA lot of effort is made by pharmaceutical companies on the research and development of new pharmaceutical products and processes using the latest in quality by design tools, and process analytical technologies. Older pharmaceutical processes that were developed without the use of these tools are, however, somewhat neglected. Significant quantities of process data are routinely collected and stored but the information contained within this data is not extracted. Extensive literature on multivariate statistical process monitoring and control exists for exploring both batch and continuous process data. However, these methodologies rely on data from processes that are relatively well understood or controlled. Many industrial processes show batch to batch variability, which may be tolerated as it is not detrimental to the quality of the product, and the impact of this variability is not fully understood. The thesis presents a framework for exploring historical batch process data, to extract insights on where process control can be improved. The challenges presented with commercial process data are discussed. Multivariate tools such as multi-way principal component analysis are used to investigate variability in process data. The framework presented discusses the pre-processing steps necessary with batch process data, followed by outlier detection, and finally multivariate modelling of the data to identify where the process could benefit from improved understanding and control. This framework is demonstrated through the application to commercial process data from the active pharmaceutical drug substance manufacturing process of spironolactone at Piramal Healthcare, Morpeth, UK. In this case study, the process exhibits variability in drying times which traditional univariate data analysis has not been able to solve. The results demonstrated some of the challenges the use of the available data from commercial processes. Although the results from the multivariate data analysis did not show a significant statistical difference between the batches with long and short drying times, small differences were observed between these two groups. Further analysis of the crystallization process using infrared spectroscopic techniques which identified a potential root cause to the extended drying time.This EngD project was supported by the Engineering and Physical Sciences Research Council (EPSRC) and Piramal Healthcare, Morpeth

Reactivity of a syn-bimetallic pentalene titanium complex: synthesis of alkyl complexes and related adducts

The introductory chapter of this thesis shall discuss the structure, binding modes and practical application of the pentalene ligand in organometallic chemistry. The synthesis and properties of the bimetallic titanium pentalene compound [Ti(μ:η5,η5-Pn†)]2 1.1 shall be focused upon in particular, as this compound is an important component of many of the experiments performed in this work. Examples of established transition metal cyclopentadienyl complex chemistry will also be discussed with a view to how the rationale behind these reactions may be applied to further the field of pentalene chemistry. The second chapter of this thesis focuses entirely upon the dehydrogenation of amineboranes, a process that 1.1 was found to catalyse. A discussion of the significance of this reaction and its real world applications will be presented, followed by a brief summary of existing catalytic species reported in the literature. The characterisation data obtained for a novel pentalene complex isolated from the reaction mixture will be analysed in detail. Chapter Three describes the synthesis of a variety of titanium pentalene metal halide compounds with the objective of providing synthetic precursors for the isolation of further novel pentalene compounds. Efforts expended towards the optimisation of these synthetic routes shall also be discussed. Chapter Four chronicles the further development of the chemistry discussed in Chapter Three, with the targeted synthesis of pentalene titanium metal alkyl complexes from pentalene titanium halides. The characterisation of these compounds, their stability and their reactivity is documented. Chapter Five provides a summary of reactions performed between compound 1.1 and neutral L-type ligands. Highlights include the reaction of 1.1 with ethylene, butadiene and xylylisocyanide

Offshore wind farm service vessel, hull design optimisation

Access to a wind turbine is a major issue, currently there is a 1.5m significant wave height (Hs) limit for the standard “step over” method for transferring personnel to an offshore wind turbine. According to the Carbon Trust being able to access, wind turbines at a wave height of 3m would be worth ₤3 billion to the offshore wind industry. The current research addresses this issue by examining a novel multihull design concept for an Offshore Wind Farm Service Vessel. The objective of this work is to carry out a feasibility study of the proposed design as previous research indicated that the design reduces the heave and pitch motions by dampening its response to the wave motion. The proposed design is analysed with both hydrostatic and hydrodynamic analysis using the computational fluid dynamic (CFD) package ANSYS CFX. Also to be undertaken is physical model testing of the analysed design in the National Ocean Test Facility’s wave basin to determine the accuracy of the computational analysis

Kansas v. Boettger: On Petition for a Writ of Certiorari to the Supreme Court of the State of Kansas

This amicus brief in support of Kansas’ petition for certiorari in Kansas v. Boettger discusses the important issue of whether the First Amendment require proof of specific intent to criminally punish violent threats. The brief argues that the First Amendment does not contain any such requirement and that creating any such requirement would interfere with effective prosecution of domestic violence. The Kansas Supreme Court’s decision over which review is being sought required the state to prove that an abuser had a specific intent to cause fear. If allowed to stand, the decision will make prosecuting and preventing domestic violence even more challenging, without any corresponding benefit. In domestic violence cases, there is rarely direct evidence of specific intent, and domestic-violence victims often struggle to confront their abusers in court. Indeed, the impact of abusers’ psychological, emotional, and physical abuse is often so severe that victims frequently struggle even to seek help. The Kansas Supreme Court’s decision to impose a specific intent requirement in a case involving violent threats is inconsistent with decisions from other courts, the law in over a dozen states, the Model Penal Code, and the history and tradition of the First Amendment. This amicus brief concludes that the Supreme Court should grant certiorari to review the decision below and reverse it

Mothers in the Military: Effect of Maternity Leave Policy on Take-Up

DRAFT VersionThe article of record as published may be found at https://doi.org/10.1215/00703370-9816044The United States remains the only OECD nation without national paid maternity leave. This paper exploits changes in paid maternity leave offered by one of its largest employers, the U.S. Department of Defense. Since 2015, the U.S. Marine Corps has shifted their maternity leave policy from six to 18 to 12 weeks. Leave expansions increased leave duration while contractions decreased leave taken by active-duty service members. However, the policy changes crowded out other forms of leave: with an increase in maternity leave available, mothers increased use of maternity leave and stopped supplementing with additional annual leave. Though all mothers used the full six weeks of leave in the early period, it is the less advantaged mothers—in the enlisted ranks, first-time, and single mothers—who disproportionately used more of the additional leave than officers, experienced mothers, and married mothers. Pregnant officers, experienced mothers, and single women use less leave than non-pregnant women in the months leading up to birth, but expecting additional post-birth leave did not change average pre-birth leave-taking. Our results highlight the importance of optimally sizing family leave policies and provide evidence that the true cost of such programs may be lower than the raw count of weeks provided by additional maternity leave allowances

Bromoform-assisted aqueous free radical polymerisation: a simple, inexpensive route for the preparation of block copolymers

In the quest for commercially relevant block copolymer additives, for which overall average molecular composition is key but molar mass distribution is of little importance, we present a straightforward, sulfur- and metal-free aqueous route to block copolymers using commercially available starting materials. Based on synthetic techniques first described in the 1950s for hydrophobic monomers in organic solvents, we have shown that bromoform (CHBr3) can be used to create block copolymers. Unlike common bromine-containing chain transfer agents such as carbon tetrabromide (CBr4), bromoform is partially water-miscible and relatively inexpensive. Herein, we demonstrate this new aqueous-based technology using N,N-dimethylacrylamide (DMA) and N-isopropylacrylamide (NIPAM) as exemplar monomers to synthesise PDMA-b-PNIPAM block copolymers of varying composition directly in water. This study demonstrates the potential for such a simple, inexpensive route to functional block copolymers where further research to decipher the detailed mechanism and true potential of this technique will be of great value