The Spectral Variability of Astronomical PAHs

Polycyclic aromatic hydrocarbons (PAHs) are highly abundant molecules found throughout the universe. Illuminated by ultraviolet photons, they can emit up to 10% of the total power output of star-forming galaxies and are involved in many important physical and chemical processes (e.g., gas heating). They produce prominent emission bands between 3-20 μm which vary strongly in intensity and spectral profile. The origins of these variations are not fully understood, which limits the use of PAHs as (ubiquitous) diagnostic tracers of physical conditions. To characterize their variability, we studied the relative intensities and profiles of the 10-20 μm PAH bands in a varied sample of objects, including several extended Galactic sources. Our overarching conclusion is that charge is the dominant parameter in determining the strengths and/or shapes of the 10-20 μm bands. While some bands are due to a single charge state, others exhibit mixed contributions--the mixing ratios of which determine the overall band shape and thus drive the profile variations. We also investigate the nature of the surprisingly strong PAH emission observed in lines of sight toward the Galactic bulge. These sight lines are not associated with any known stellar sources. We use forbidden emission lines and spectral energy distributions to determine the physical conditions and relate these to the observed variability of the PAH emission bands, hypothesizing about possible origins of the excitation

The Molecular Biology of Sickle Cell Anaemia

Sickle cell anaemia (SCA) is a haemolytic anaemia that reduces life expectancy and places a great burden on healthcare systems worldwide. Despite being a monogenic disorder, the phenotypic severity varies greatly between patients, ranging from patients that experience multiple strokes and organ failure during childhood, to those that live largely unaffected lives. Some genetic variants that affect globin gene expression are known to influence phenotype severity, but most of this variation remains unaccounted for. We conducted whole exome sequencing analyses, comparing SCA patients with mild and severe clinical phenotypes, with the aim of identifying novel genetic modifiers of the disease. SCA patient exomes were sequenced from a cohort at King’s College Hospital, and combined with publicly available SCA exomes recruited in the United States. Nine candidate variants were identified in genes with plausible mechanisms to influence the pathophysiology of the disease. The genes identified in this study affected nitric oxide signalling, haematopoietic regulation, globin gene expression and recovery from ischaemic injury. In order to evaluate these variants, a CRISPR genomic editing pipeline was established and tested on two previously identified candidate modifiers of SCA, in the genes ASH1L and KLF1. These variants were successfully introduced into erythroleukaemic cells and provide a pathway for testing the novel modifier genes identified in the exome sequencing analysis. Preliminary studies indicate that both ASH1L and KLF1 variants alter globin gene expression. In addition to genetic factors, we also hypothesised that epigenetic factors affect the SCA phenotype, and play a role in the therapeutic mechanism of hydroxyurea treatment. We optimised a method for isolating CD45+CD71+GPA- nucleated erythroid progenitors from small volumes of SCA peripheral blood. This was undertaken to evaluate the role of the epigenome in SCA phenotype severity and drug action, but for which patient sample collection proved too challenging within our clinical cohort

New organometallic catalysts for process-friendly redox neutral alkylations

Borrowing hydrogen chemistry is a convenient method of carrying out alkylation reactions, by forming carbonyl compounds from alcohols in situ, creating more reactive intermediates. These aldehydes or ketones react and the resulting product is reduced by return of the hydrogen abstracted from the alcohol starting material. Previous work within the Marsden group led to the development of a new family of catalysts for N-alkylation borrowing hydrogen reactions, featuring a Cp* ligand functionalised with an amine tether. The possibility for expanding the scope of these catalysts to polyfunctionalised compounds was investigated, including protected and unprotected diamines and diols, and the synthesis of pharmaceutically relevant compounds. Optimisation studies were carried out to reach the highest turnover number for our catalyst, reaching a maximum turnover number of 2250 for our model reaction of the alkylation of piperidine with benzyl alcohol. After a brief investigation into the synthesis of new catalysts bearing modified tethers was unsuccessful, methodology was developed for the synthesis of our original catalyst under conditions more viable for scale-up. Experiments were carried out to determine the catalyst’s potential for carrying out C-alkylation reactions. In particular, carbonyl alkylations via an aldol pathway were successful, and were shown to be viable for a series of substituted acetophenones and benzyl alcohols, as well as various heteroaromatic compounds. A one-pot procedure for alkylation and subsequent reduction to the respective alcohol compound was developed and utilised to synthesise a series of compounds based on the taccabulin natural products, which were tested for anti-cancer activity. Finally, the possibility of these reactions being carried out to a lower yield in the absence of catalyst was investigated. The scope of these uncatalyzed reactions was determined to include only aromatic ketones, while our catalyst was shown to be able to carry out alkylations onto alkyl ketones with either aromatic or alkyl alcohols

“They are kids, they’re making bad choices, but they are not bad kids” : Motivations and deterrents for joyriding amongst Australian youth

Car theft and joyriding are becoming increasingly common in regional areas of Australia. Whilst the consequences of these actions can be fatal, surprisingly little is known about the motivations for young people who engage in these behaviours. This exploratory study draws from 17 in-depth interviews that were conducted as part of a pilot intervention program aimed at adolescents either already engaged or susceptible to car theft and joyriding behaviours. The findings suggest that joyriding predominately attracts disenfranchised youth who lack opportunities for education, employment, and leisure. For these adolescents, joyriding emerges to counterbalance disadvantage and alleviate the monotony in their lives. Interviewees also provide suggestions for deterring joyriding, such as providing young people with occupational opportunities that allow them to serve as role models to themselves and others and adrenaline-based activities to replace the thrills of joyriding

Anti-Human TraffickingA Descriptive Study of Adult Education Programs in Relationship to Policy and Funding (Empirical)

In this study, I describe anti-human trafficking organizations with an educational mission. Organizations vary based on educational approach, location, gender, and age served, and founder’s gender. I categorize the organizations using these factors and illustrate organizations’ characteristics and their impact on funding through descriptive statistics

The Alt-Right Movement and National Security

Identifying the January 6 insurrection at the US Capitol as an inflection point, this article analyzes the historical relationship between White supremacy and the US military from Reconstruction after the Civil War to the present. The article posits causes for the disproportionate number of current and former members of the military associated with White power groups and proposes steps the Department of Defense can take to combat the problems posed by the association of the US military with these groups

The relative efficacy of cues for two-dimensional shape perception

AbstractThe visual system uses a variety of cues for form perception, including motion, color, binocular disparity, texture, and luminance. Physiological evidence suggests that these cues are processed by different neural mechanisms. Do the cues processed by some mechanisms convey any advantage for form perception when compared to cues processed by another? In response to this question we assessed the relative efficiency of several cues in conveying two-dimensional form from background noise. For the sake of comparison, every cue type used the same experimental design and stimulus set. Our results confirm that movement is one of the most efficient cues for shape perception. Also, a simple transient cue (an instantaneous flashing on or off) is equally useful. In comparison, local dot density (a type of texture cue) was the least efficient. The efficiencies of most other cues, such as color, stereopsis, and relative movement in noise, were conspicuously similar