The preparation, identification and properties of chlorophyll derivatives

In the investigation of 10-hydroxy chlorophylls a and b novel techniques included modification of chromatography and the use of fully-deuterated compounds isolated from fully-deuterated autotropic algae to determine the molecular structure of the chlorophylls

Hair radioactivity as a measure of exposure to radioisotopes

Since many radioisotopes accumulate in hair, this tropism was investigated by comparing the radioactivity of shaved with plucked hair collected from rats at various time intervals up to 24 hrs after intravenous injection of the ecologically important radioisotopes, iodine-131, manganese-54, strontium-85, and zinc-65. The plucked hair includes the hair follicles where biochemical transformations are taking place. The data indicate a slight surge of each radioisotpe into the hair immediately after injection, a variation of content of each radionuclide in the hair, and a greater accumulation of radioactivity in plucked than in shaved hair. These results have application not only to hair as a measure of exposure to radioisotopes, but also to tissue damage and repair at the hair follicle

Control sideband generation for dual-recycled laser interferometric gravitational wave detectors

We present a discussion of the problems associated with generation of multiple control sidebands for length sensing and control of dual-recycled, cavity-enhanced Michelson interferometers and the motivation behind more complicated sideband generation methods. We focus on the Mach–Zehnder interferometer as a topological solution to the problem and present results from tests carried out at the Caltech 40 m prototype gravitational wave detector. The consequences for sensing and control for advanced interferometry are discussed, as are the implications for future interferometers such as Advanced LIGO

Hilbert Expansion from the Boltzmann equation to relativistic Fluids

We study the local-in-time hydrodynamic limit of the relativistic Boltzmann equation using a Hilbert expansion. More specifically, we prove the existence of local solutions to the relativistic Boltzmann equation that are nearby the local relativistic Maxwellian constructed from a class of solutions to the relativistic Euler equations that includes a large subclass of near-constant, non-vacuum fluid states. In particular, for small Knudsen number, these solutions to the relativistic Boltzmann equation have dynamics that are effectively captured by corresponding solutions to the relativistic Euler equations.Comment: 50 page

Nonlinear effects in silicon waveguides

In this work, we modelled the nonlinear effects in silicon waveguides which are crucial for many applications, including all-optical signal processing, switching, wavelength conversion. I have developed the model for ultrafast all-optical switching using split-step Fourier method and calculated the nonlinear phase shift due to the Kerr effect and including the nonlinear losses (i.e. two-photon absorption, free carrier absorption and free carrier index)

Experimental demonstration of coupled optical springs

Optical rigidity will play an important role in improving the sensitivity of future generations of gravitational wave (GW) interferometers, which employ high laser power in order to reach and exceed the standard quantum limit. Several experiments have demonstrated the combined effect of two optical springs on a single system for very low-weight mirror masses or membranes. In this paper we investigate the complex interactions between multiple optical springs and the surrounding apparatus in a system of comparable dynamics to a large-scale GW detector. Using three 100 g mirrors to form a coupled cavity system capable of sustaining two or more optical springs, we demonstrate a number of different regimes of opto-mechanical rigidity and measurement techniques. Our measurements reveal couplings between each optical spring and the control loops that can affect both the achievable increase in sensitivity and the stability of the system. Hence this work establishes a better understanding of the realisation of these techniques and paves the way to their application in future GW observatories, such as upgrades to Advanced LIGO

Demonstration of detuned dual recycling at the Garching 30m laser interferometer

Dual recycling is an advanced optical technique to enhance the signal-to-noise ratio of laser interferometric gravitational wave detectors in a limited bandwidth. To optimise the center of this band with respect to Fourier frequencies of expected gravitational wave signals detuned dual recycling has to be implemented. We demonstrated detuned dual recycling on a fully suspended 30m prototype interferometer. A control scheme that allows to tune the detector to different frequencies will be outlined. Good agreement between the experimental results and numerical simulations has been achieved.Comment: 9 page

Analysis of a four-mirror cavity enhanced Michelson interferometer

We investigate the shot noise limited sensitivity of a four-mirror cavity enhanced Michelson interferometer. The intention of this interferometer topology is the reduction of thermal lensing and the impact of the interferometers contrast although transmissive optics are used with high circulating powers. The analytical expressions describing the light fields and the frequency response are derived. Although the parameter space has 11 dimensions, a detailed analysis of the resonance feature gives boundary conditions allowing systematic parameter studies

The systemic microcirculation in dialysis populations

In a rapidly expanding population of patients with chronic kidney disease, including 2 million people requiring renal replacement therapy, cardiovascular mortality is 15 times greater than the general population. In addition to traditional cardiovascular risk factors, more poorly defined risks related to uremia and its treatments appear to contribute to this exaggerated risk. In this context, the microcirculation may play an important early role in cardiovascular disease associated with chronic kidney disease. Experimentally, the uremic environment and dialysis have been linked to multiple pathways causing microvascular dysfunction. Coronary microvascular dysfunction is reflected in remote and more easily studied vascular beds such as the skin. There is increasing evidence for a correlation between systemic microvascular dysfunction and adverse cardiovascular outcomes. Systemic microcirculatory changes have not been extensively investigated across the spectrum of chronic kidney disease. Recent advances in non-invasive techniques studying the microcirculation in vivo in man are increasing the data available particularly in patients on hemodialysis. Here, we review current knowledge of the systemic microcirculation in dialysis populations, explore whether non-invasive techniques to study its function could be used to detect early stage cardiovascular disease, address challenges faced in studying this patient cohort and identify potential future avenues for research.This article is freely available via Open Access. Click on the publisher URL to access it via the publisher's site.Jennifer Williams is funded by a Kidney Research UK Training Fellowship TF_013_20151127.pre-print, post-print (12 month embargo

Experimental test of higher-order Laguerre–Gauss modes in the 10 m Glasgow prototype interferometer

Brownian noise of dielectric mirror coatings is expected to be one of the limiting noise sources, at the peak sensitivity, of next generation ground based interferometric gravitational wave (GW) detectors. The use of higher-order Laguerre–Gauss (LG) beams has been suggested to reduce the effect of coating thermal noise in future generations of gravitational wave detectors. In this paper we describe the first test of interferometry with higher-order LG beams in an environment similar to a full-scale gravitational wave detector. We compare the interferometric performance of higher-order LG modes and the fundamental mode beams, injected into a 10 m long suspended cavity that features a finesse of 612, a value chosen to be typical of future gravitational wave detectors. We found that the expected mode degeneracy of the injected LG3, 3 beam was resolved into a multiple peak structure, and that the cavity length control signal featured several nearby zero crossings. The break up of the mode degeneracy is due to an astigmatism (defined as |Rcy − Rcx|) of 5.25 ± 0.5 cm on one of our cavity mirrors with a radius of curvature (Rc) of 15 m. This observation agrees well with numerical simulations developed with the FINESSE software. We also report on how these higher-order mode beams respond to the misalignment and mode mismatch present in our 10 m cavity. In general we found the LG3, 3 beam to be considerably more susceptible to astigmatism and mode mismatch than a conventional fundamental mode beam. Therefore the potential application of higher-order Laguerre–Gauss beams in future gravitational wave detectors will impose much more stringent requirements on both mode matching and mirror astigmatism