Single-trial multiwavelet coherence in application to neurophysiological time series

A method of single-trial coherence analysis is presented, through the application of continuous muldwavelets. Multiwavelets allow the construction of spectra and bivariate statistics such as coherence within single trials. Spectral estimates are made consistent through optimal time-frequency localization and smoothing. The use of multiwavelets is considered along with an alternative single-trial method prevalent in the literature, with the focus being on statistical, interpretive and computational aspects. The multiwavelet approach is shown to possess many desirable properties, including optimal conditioning, statistical descriptions and computational efficiency. The methods. are then applied to bivariate surrogate and neurophysiological data for calibration and comparative study. Neurophysiological data were recorded intracellularly from two spinal motoneurones innervating the posterior,biceps muscle during fictive locomotion in the decerebrated cat

Asymmetric synthesis 1,2,3-triazoles utilising the copper-catalysed azide-alkyne cycloaddition

The copper-catalysed azide-alkyne cycloaddition (CuAAC) is a highly efficient reaction and is the cornerstone of “click” chemistry. However, unlike many common metal-mediated transformations asymmetric CuAAC variants are relatively sparse. This thesis details asymmetric “click” reactions with Chapter 1 introducing the CuAAC and the asymmetric variants already present in the literature. Chapter 2 outlines research demonstrating the first example of kinetic resolution of an alkyne via a CuAAC reaction. Selectivity factors of up to 22.1 ± 0.5 were obtained and triazoles and alkynes were obtained in ≤ 80% enantiomeric excess (ee). This chapter also contains a study on the simultaneous kinetic resolution of azides and alkynes; azides were obtained in >30% $e$$e$, alkynes in >40% $e$$e$ and a triazolic diastereomeric product was obtained in up to 90% $e$$e$. In Chapter 3 the Bull-James three-component boronic acid assembly is successfully employed for the kinetic resolution of primary amine alkynes with selectivity factors of up to 4.1 obtained. The principle behind the assembly is also elaborated upon in this chapter leading to its use in both dynamic combinatorial chemistry and as a pedagogical tool. Chapter 4 details work on atropisomerism in triazolic systems. A series of novel triazoles, iodotriazoles and triazolium salts were successfully synthesised and their atropisomeric stability probed. Chapter 5 presents feasibility studies towards the asymmetric synthesis of 5,5’-bis(triazoles) and ruthenium olefin metathesis catalysts in the formation of 1,5-triazoles

Post-Outburst Observations of V1647 Ori: Detection of a Brief Warm, Molecular Outflow

We present new observations of the fundamental ro-vibrational CO spectrum of V1647 Ori, the young star whose recent outburst illuminated McNeil's Nebula. Previous spectra, acquired during outburst in 2004 February and July, had shown the CO emission lines to be broad and centrally peaked-similar to the CO spectrum of a typical classical T Tauri star. In this paper, we present CO spectra acquired shortly after the luminosity of the source returned to its pre-outburst level (2006 February) and roughly one year later (2006 December and 2007 February). The spectrum taken in 2006 February revealed blue-shifted CO absorption lines superimposed on the previously observed CO emission lines. The projected velocity, column density, and temperature of this outflowing gas was 30 km/s, 3^{+2}_{-1}E18 cm^{-2$, and 700^{+300}_{-100} K, respectively. The absorption lines were not observed in the 2006 December and 2007 February data, and so their strengths must have decreased in the interim by a factor of 9 or more. We discuss three mechanisms that could give rise to this unusual outflow.Comment: 14 pages, 2 figures, accepted for publication in ApJ

Coping with cognitive impairment in people with Parkinson’s disease and their carers: a qualitative study

Cognitive impairment is common in Parkinson’s disease (PD). However, the psychosocial impact of living and coping with PD and cognitive impairment in people with PD and their carers have not been explored. This paper draws on a qualitative study that explores the subjective impact of cognitive impairment on people with PD and their carers. Thirty-six one-to-one interviews were completed; people with PD were from three groups: normal cognition, mild cognitive impairment and dementia. Data collection and analysis were iterative and verbatim transcripts were analysed using thematic analysis. Themes were interpreted in consultation with coping and adaptation theory. The analysis revealed four main themes: threats to identity and role, pre-death grief and feelings of loss in carers, success and challenges to coping in people with PD, and problem focused coping and finding meaning in caring. Our data highlights how cognitive impairment can threaten an individual’s self-perception and their perceived role; the ostensible effects depended on the impact individual’s perceived cognitive impairment on their daily lives. For carers, cognitive impairment had a greater emotional impact compared to the physical symptoms of PD. The discussion that developed around protective factors provides possible opportunities for future interventions, such as psychological therapies to improve successful adjustment

The Gas/Dust Ratio of Circumstellar Disks: Testing Models of Planetesimal Formation

We present high-resolution, near-infrared NIRSPEC observations of CO absorption toward six class II T Tauri stars: AA Tau, DG Tau, IQ Tau, RY Tau, CW Tau, and Haro 6–5b. 12CO overtone absorption lines originating from the circumstellar disk of each object were used to calculate line-of-sight gas column densities toward each source. We measured the gas/dust ratio as a function of disk inclination, utilizing measured visual extinctions and inclinations for each star. The majority of our sources show further evidence for a correlation between the gas/dust columndensity ratio and disk inclination similar to that found by Rettig et al

Dust Stratification in Young Circumstellar Disks

We present high-resolution infrared spectra of four YSOs (T Tau N, T Tau S, RNO 91, and HL Tau). The spectra exhibit narrow absorption lines of 12CO, 13CO, and C18O as well as broad emission lines of gas phase12CO. The narrow absorption lines of CO are shown to originate from the colder circumstellar gas. We find that the line of sight gas column densities resulting from the CO absorption lines are much higher than expected for the measured extinction for each source and suggest the gas to dust ratio is measuring the dust settling and/or grain coagulation in these extended disks. We provide a model of turbulence, dust settling and grain growth to explain the results. The techniques presented here allow us to provide some observationally-motivated bounds on accretion disk alpha in protostellar systems

Microbial Diffraction Gratings as Optical Detectors for Heavy Metal Pollutants

As a significant industrial pollutant, cadmium is implicated as the cause of itai-itai disease. For biological detection of cadmium toxicity, an assay device has been developed using the motile response of the protozoa species, Tetrahymena pyriformis. This mobile protozoa measures 50 microns in diameter, swims at 10 body lengths per second, and aggregates into macroscopically visible patterns at high organism concentrations. The assay demonstrates a Cd(+2) sensitivity better than 1 micro-M and a toxicity threshold to 5 micro-M, thus encouraging the study of these microbial cultures as viable pollution detectors. Using two-dimensional diffraction patterns within a Tetrahymena culture, the scattered light intensity varies with different organism densities (population counts). The resulting density profile correlates strongly with the toxic effects at very low dosages for cadmium (less than 5 ppm) and then for poison protection directly (with nickel and copper antagonists competing with cadmium absorption). In particular, copper dosages as low as 0.1-0.5 mM Cu have shown protective antagonism against cadmium, have enhanced density variability for cultures containing 1 mM Cd(+2) and therefore have demonstrated the sensitivity of the optical detection system. In this way, such microbial diffraction patterns give a responsive optical measure of biological culture changes and toxicity determination in aqueous samples of heavy metals and industrial pollutants

Case report: a diagnostically challenging conjunctival mass caused by the Epstein-Barr virus.

We present a paediatric case of infectious mononucleosis in a 13-year old, manifesting with follicular conjunctivitis and a conjunctival mass in one eye with no evidence of leucocytosis on the blood count. The diagnosis was confirmed following surgical excision and biopsy. The case represented a diagnostic challenge due to its atypism and given the steady increase in the prevalence of EBV-related ocular diseases in the last years, this report can serve as an example to prompt earlier serological tests to identify the aetiology in similar cases. This is important because EBV can be treated with acyclovir early in the active viral phase