A study of the interactions between ylidic phosphorus species and s-blockmetals

This thesis details the synthesis and characterisation of alkaline earth metal complexes of phosphonium ylides and iminophosphoranes, together with some related phosphine oxide species. This thesis also contains the synthesis and structural characterisation of a number of novel phosphonium ylides and iminophosphoranes. Chapter 1 provides an introduction to the field of phosphonium ylides and related compounds, describing their preparation and subsequent reactivity. Chapter 2 contains an explanation of the experimental techniques and analytical tools used, whilst Chapter 3 details the syntheses and analyses for all of the complexes discussed in the thesis. Chapter 4 discusses novel alkaline earth metal phosphonium ylide complexes. The chapter contains the first structurally characterised neutral phosphonium ylide complexes of calcium, strontium and barium with the general formula (Ph(_3)PCH(_2))(_2) M[N(SiMe(_3))(_2)](_2), where M = Ca, Sr and Ba. The analogous iminophosphorane and phosphine oxide complexes are discussed in detail in chapter 5. Complexes of the general formula (Ph(_3)PNH)(_2) M[0C(_6)H2(Me)(^1)Bu(_2)](_2),(Ph(_3)P0)(_2) M[0C(_6)H(_2)(Me)’Bu(_2)](_2) and (Ph(_3)PO)(_2) M[N(SiMe(_3))(_2)](_2), are described where M =Ca, Sr and Ba. Chapter 6 details the synthesis of novel litbiated iminophosphoranes and related compounds as well as the synthesis of a novel dianion [Ph(_2)(PhCH')PN"] for use in synthetic organic chemistry. The final Chapter (7) details the synthesis and structural characterisation of a number of novel phosphonium ylides Ph(_2)R'PCHR" and iminophosphoranes Ph(_2)R’’’PNH and their corresponding salts e.g Ph(_2)R'PTH(_2)R"X and Ph(_2)R 'P+NH(_2)X

The Australia Telescope 20 GHz (AT20G) Survey: The Bright Source Sample

The Australia Telescope 20 GHz (AT20G) Survey is a blind survey of the whole Southern sky at 20 GHz (with follow-up observations at 4.8 and 8.6 GHz) carried out with the Australia Telescope Compact Array (ATCA) from 2004 to 2007. The Bright Source Sample (BSS) is a complete flux-limited subsample of the AT20G Survey catalogue comprising 320 extragalactic (|b|>1.5 deg) radio sources south of dec = -15 deg with S(20 GHz) > 0.50 Jy. Of these, 218 have near simultaneous observations at 8 and 5 GHz. In this paper we present an analysis of radio spectral properties in total intensity and polarisation, size, optical identifications and redshift distribution of the BSS sources. The analysis of the spectral behaviour shows spectral curvature in most sources with spectral steepening that increases at higher frequencies (the median spectral index \alpha, assuming S\propto \nu^\alpha, decreases from \alpha_{4.8}^{8.6}=0.11 between 4.8 and 8.6 GHz to \alpha_{8.6}^{20}=-0.16 between 8.6 and 20 GHz), even if the sample is dominated by flat spectra sources (85 per cent of the sample has \alpha_{8.6}^{20}>-0.5). The almost simultaneous spectra in total intensity and polarisation allowed us a comparison of the polarised and total intensity spectra: polarised fraction slightly increases with frequency, but the shapes of the spectra have little correlation. Optical identifications provided an estimation of redshift for 186 sources with a median value of 1.20 and 0.13 respectively for QSO and galaxies.Comment: 34 pages, 19 figures, tables of data included, replaced with version published in MNRA

First radial velocity results from the MINiature Exoplanet Radial Velocity Array (MINERVA)

The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA's unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA's robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph's intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional "sum-of-Gaussians" instrumental profile: 1.8 m s$^{-1}$ over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.Comment: 22 pages, 9 figures, submitted to PASP, Peer-Reviewed and Accepte

Symbol Nomenclature for Graphical Representations of Glycans

ISSN:0959-665

Inflation and Dark Energy from spectroscopy at z > 2

The expansion of the Universe is understood to have accelerated during two epochs: in its very first moments during a period of Inflation and much more recently, at z < 1, when Dark Energy is hypothesized to drive cosmic acceleration. The undiscovered mechanisms behind these two epochs represent some of the most important open problems in fundamental physics. The large cosmological volume at 2 < z < 5, together with the ability to efficiently target high-$z$ galaxies with known techniques, enables large gains in the study of Inflation and Dark Energy. A future spectroscopic survey can test the Gaussianity of the initial conditions up to a factor of ~50 better than our current bounds, crossing the crucial theoretical threshold of $\sigma(f_{NL}^{\rm local})$ of order unity that separates single field and multi-field models. Simultaneously, it can measure the fraction of Dark Energy at the percent level up to $z = 5$, thus serving as an unprecedented test of the standard model and opening up a tremendous discovery space

Jupiter’s auroras during the Juno approach phase as observed by the Hubble Space Telescope

We present movies of the Hubble Space Telescope (HST) observations of Jupiter’s FUV auroras observed during the Juno approach phase and first capture orbit, and compare with Juno observations of the interplanetary medium near Jupiter and inside the magnetosphere. Jupiter’s FUV auroras indicate the nature of the dynamic processes occurring in Jupiter’s magnetosphere, and the approach phase provided a unique opportunity to obtain a full set of interplanetary data near to Jupiter at the time of a program of HST observations, along with the first simultaneous with Juno observations inside the magnetosphere. The overall goal was to determine the nature of the solar wind effect on Jupiter’s magnetosphere. HST observations were obtained with typically 1 orbit per day over three intervals: 16 May – 7 June, 22-30 June and 11-18 July, i.e. while Juno was in the solar wind, around the bow shock and magnetosphere crossings, and in the mid-latitude middle-outer magnetospheres. We show that these intervals are characterised by particularly dynamic polar auroras, and significant variations in the auroral power output caused by e.g. dawn storms, intense main emission and poleward forms. We compare the variation of these features with Juno observations of interplanetary compression regions and the magnetospheric environment during the intervals of these observations

Long-term cognitive outcomes in tuberous sclerosis complex.

AIM: To investigate the interdependence between risk factors associated with long-term intellectual development in individuals with tuberous sclerosis complex (TSC). METHOD: The Tuberous Sclerosis 2000 Study is a prospective longitudinal study of individuals with TSC. In phase 1 of the study, baseline measures of intellectual ability, epilepsy, cortical tuber load, and mutation were obtained for 125 children (63 females, 62 males; median age=39mo). In phase 2, at an average of 8 years later, intellectual abilities were estimated for 88 participants with TSC and 35 unaffected siblings. Structural equation modelling was used to determine the risk pathways from genetic mutation through to IQ at phase 2. RESULTS: Intellectual disability was present in 57% of individuals with TSC. Individuals without intellectual disability had significantly lower mean IQ compared to unaffected siblings, supporting specific genetic factors associated with intellectual impairment. Individuals with TSC who had a slower gain in IQ from infancy to middle childhood were younger at seizure onset and had increased infant seizure severity. Structural equation modelling indicated indirect pathways from genetic mutation, to tuber count, to seizure severity in infancy, through to IQ in middle childhood and adolescence. INTERPRETATION: Early-onset and severe epilepsy in the first 2 years of life are associated with increased risk of long-term intellectual disability in individuals with TSC, emphasizing the importance of early and effective treatment or prevention of epilepsy. WHAT THIS PAPER ADDS: Intellectual disability was present in 57% of individuals with tuberous sclerosis complex (TSC). Those with TSC without intellectual disability had significantly lower mean IQ compared to unaffected siblings. Earlier onset and greater severity of seizures in the first 2 years were observed in individuals with a slower gain in intellectual ability. Risk pathways through seizures in the first 2 years predict long-term cognitive outcomes in individuals with TSC

A Population Genetic Approach to Mapping Neurological Disorder Genes Using Deep Resequencing

Deep resequencing of functional regions in human genomes is key to identifying potentially causal rare variants for complex disorders. Here, we present the results from a large-sample resequencing (n = 285 patients) study of candidate genes coupled with population genetics and statistical methods to identify rare variants associated with Autism Spectrum Disorder and Schizophrenia. Three genes, MAP1A, GRIN2B, and CACNA1F, were consistently identified by different methods as having significant excess of rare missense mutations in either one or both disease cohorts. In a broader context, we also found that the overall site frequency spectrum of variation in these cases is best explained by population models of both selection and complex demography rather than neutral models or models accounting for complex demography alone. Mutations in the three disease-associated genes explained much of the difference in the overall site frequency spectrum among the cases versus controls. This study demonstrates that genes associated with complex disorders can be mapped using resequencing and analytical methods with sample sizes far smaller than those required by genome-wide association studies. Additionally, our findings support the hypothesis that rare mutations account for a proportion of the phenotypic variance of these complex disorders

Effects of sleep disturbance on dyspnoea and impaired lung function following hospital admission due to COVID-19 in the UK:a prospective multicentre cohort study

BACKGROUND: Sleep disturbance is common following hospital admission both for COVID-19 and other causes. The clinical associations of this for recovery after hospital admission are poorly understood despite sleep disturbance contributing to morbidity in other scenarios. We aimed to investigate the prevalence and nature of sleep disturbance after discharge following hospital admission for COVID-19 and to assess whether this was associated with dyspnoea. METHODS: CircCOVID was a prospective multicentre cohort substudy designed to investigate the effects of circadian disruption and sleep disturbance on recovery after COVID-19 in a cohort of participants aged 18 years or older, admitted to hospital for COVID-19 in the UK, and discharged between March, 2020, and October, 2021. Participants were recruited from the Post-hospitalisation COVID-19 study (PHOSP-COVID). Follow-up data were collected at two timepoints: an early time point 2-7 months after hospital discharge and a later time point 10-14 months after hospital discharge. Sleep quality was assessed subjectively using the Pittsburgh Sleep Quality Index questionnaire and a numerical rating scale. Sleep quality was also assessed with an accelerometer worn on the wrist (actigraphy) for 14 days. Participants were also clinically phenotyped, including assessment of symptoms (ie, anxiety [Generalised Anxiety Disorder 7-item scale questionnaire], muscle function [SARC-F questionnaire], dyspnoea [Dyspnoea-12 questionnaire] and measurement of lung function), at the early timepoint after discharge. Actigraphy results were also compared to a matched UK Biobank cohort (non-hospitalised individuals and recently hospitalised individuals). Multivariable linear regression was used to define associations of sleep disturbance with the primary outcome of breathlessness and the other clinical symptoms. PHOSP-COVID is registered on the ISRCTN Registry (ISRCTN10980107). FINDINGS: 2320 of 2468 participants in the PHOSP-COVID study attended an early timepoint research visit a median of 5 months (IQR 4-6) following discharge from 83 hospitals in the UK. Data for sleep quality were assessed by subjective measures (the Pittsburgh Sleep Quality Index questionnaire and the numerical rating scale) for 638 participants at the early time point. Sleep quality was also assessed using device-based measures (actigraphy) a median of 7 months (IQR 5-8 months) after discharge from hospital for 729 participants. After discharge from hospital, the majority (396 [62%] of 638) of participants who had been admitted to hospital for COVID-19 reported poor sleep quality in response to the Pittsburgh Sleep Quality Index questionnaire. A comparable proportion (338 [53%] of 638) of participants felt their sleep quality had deteriorated following discharge after COVID-19 admission, as assessed by the numerical rating scale. Device-based measurements were compared to an age-matched, sex-matched, BMI-matched, and time from discharge-matched UK Biobank cohort who had recently been admitted to hospital. Compared to the recently hospitalised matched UK Biobank cohort, participants in our study slept on average 65 min (95% CI 59 to 71) longer, had a lower sleep regularity index (-19%; 95% CI -20 to -16), and a lower sleep efficiency (3·83 percentage points; 95% CI 3·40 to 4·26). Similar results were obtained when comparisons were made with the non-hospitalised UK Biobank cohort. Overall sleep quality (unadjusted effect estimate 3·94; 95% CI 2·78 to 5·10), deterioration in sleep quality following hospital admission (3·00; 1·82 to 4·28), and sleep regularity (4·38; 2·10 to 6·65) were associated with higher dyspnoea scores. Poor sleep quality, deterioration in sleep quality, and sleep regularity were also associated with impaired lung function, as assessed by forced vital capacity. Depending on the sleep metric, anxiety mediated 18-39% of the effect of sleep disturbance on dyspnoea, while muscle weakness mediated 27-41% of this effect. INTERPRETATION: Sleep disturbance following hospital admission for COVID-19 is associated with dyspnoea, anxiety, and muscle weakness. Due to the association with multiple symptoms, targeting sleep disturbance might be beneficial in treating the post-COVID-19 condition. FUNDING: UK Research and Innovation, National Institute for Health Research, and Engineering and Physical Sciences Research Council