An investigation of the Eigenvalue Calibration Method (ECM) using GASP for non-imaging and imaging detectors

Polarised light from astronomical targets can yield a wealth of information about their source radiation mechanisms, and about the geometry of the scattered light regions. Optical observations, of both the linear and circular polarisation components, have been impeded due to non-optimised instrumentation. The need for suitable observing conditions and the availability of luminous targets are also limiting factors. GASP uses division of amplitude polarimeter (DOAP) (Compain and Drevillon) to measure the four components of the Stokes vector simultaneously, which eliminates the constraints placed upon the need for moving parts during observation, and offers a real-time complete measurement of polarisation. Results from the GASP calibration are presented in this work for both a 1D detector system, and a pixel-by-pixel analysis on a 2D detector system. Following Compain et al. we use the Eigenvalue Calibration Method (ECM) to measure the polarimetric limitations of the instrument for each of the two systems. Consequently, the ECM is able to compensate for systematic errors introduced by the calibration optics, and it also accounts for all optical elements of the polarimeter in the output. Initial laboratory results of the ECM are presented, using APD detectors, where errors of 0.2% and 0.1{\deg} were measured for the degree of linear polarisation and polarisation angle respectively. Channel-to-channel image registration is an important aspect of 2-D polarimetry. We present our calibration results of the measured Mueller matrix of each sample, used by the ECM. A set of Zenith flat-field images were recorded during an observing campaign at the Palomar 200 inch telescope in November 2012. From these we show the polarimetric errors from the spatial polarimetry indicating both the stability and absolute accuracy of GASP.Comment: Accepted for publication in Experimental Astronom

Chapter 13: Vulnerability of chondrichthyan fishes of the Great Barrier Reef to climate change

This chapter addresses the potential impact of climate change on the chondrichthyan fauna of the Great Barrier Reef, that is, the sharks, rays, skates and holocephalans that occur within the Great Barrier Reef region. The terms ‘sharks and rays’ or ‘sharks’ are used throughout this chapter to describe this diverse group of fishes.This is Chapter 13 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/13

The use of monosaccharides in metal-catalyzed coupling reactions

The addition of monosaccharides to metal-catalyzed coupling reactions can be beneficial in terms of decreasing the time required, chemical waste products and overall cost of the process. Monosaccharides are used in a number of different ways, including: (a) acting as a ligand for the metal, (b) providing the appropriate reduction potential for a chemical process and (c) acting as a reducing agent for the formation and stabilization of catalytically active metal nanoparticles. Recently, there has been a significant amount of research in this growing field and there is thus the potential for the addition of monosaccharides to coupling reactions to have significant impact on the synthesis of the important small molecules on which we have all come to rely. This Perspectives Article will cover recent developments in the addition of monosaccharides to metal-catalyzed coupling reactions with an emphasis on their utility and limitations in order to facilitate the further development of this exciting area of research

CHIMERA: a wide-field, multi-color, high-speed photometer at the prime focus of the Hale telescope

The Caltech HIgh-speed Multi-color camERA (CHIMERA) is a new instrument that has been developed for use at the prime focus of the Hale 200-inch telescope. Simultaneous optical imaging in two bands is enabled by a dichroic beam splitter centered at 567 nm, with Sloan u' and g' bands available on the blue arm and Sloan r', i' and z_s' bands available on the red arm. Additional narrow-band filters will also become available as required. An Electron Multiplying CCD (EMCCD) detector is employed for both optical channels, each capable of simultaneously delivering sub-electron effective read noise under multiplication gain and frame rates of up to 26 fps full frame (several 1000 fps windowed), over a fully corrected 5 x 5 arcmin field of view. CHIMERA was primarily developed to enable the characterization of the size distribution of sub-km Kuiper Belt Objects via stellar occultation, a science case that motivates the frame-rate, the simultaneous multi-color imaging and the wide field of view of the instrument. In addition, it also has unique capability in the detection of faint near-Earth asteroids and will be used for the monitoring of short duration transient and periodic sources, particularly those discovered by the intermediate Palomar Transient Factory (iPTF), and the upcoming Zwicky Transient Facility (ZTF).Comment: Accepted to Mon. Not. R. Astron. Soc. (MNRAS), 15 pages, 9 figures, 3 table

One-pot near-ambient temperature syntheses of aryl(difluoroenol) derivatives from trifluoroethanol

Difluoroalkenylzinc reagents prepared from 1-(2’-methoxy-ethoxymethoxy)-2,2,2-trifluoroethane and 1-(N,N-diethylcarbamoyloxy)-2,2,2-trifluoroethane at ice bath temperatures, underwent Negishi coupling with a range of aryl halides in a convenient one pot procedure. While significant differences between the enol acetal and carbamate reagents were revealed, the Negishi protocol compared very favourably with alternative coupling procedures in terms of overall yields from trifluoroethanol