Micro-computed tomography beamline of the Australian synchrotron: Density measurements.

The Micro-Computed Tomography (MCT) beamline at the Australian Synchrotron (ANSTO) offers superior capabilities in micrometer-scale spatial resolution and three-dimensional x-ray imaging. MCT is the first of the eight new BRIGHT beamlines and has been operating successfully with users for approximately two years. It is a bending magnet beamline capable of delivering a white beam, a pink beam, or a monochromatic beam in the 8-40 keV energy range using a Double Multilayer Monochromator (DMM).

Precise phase retrieval for propagation-based images using discrete mathematics.

The ill-posed problem of phase retrieval in optics, using one or more intensity measurements, has a multitude of applications using electromagnetic or matter waves. Many phase retrieval algorithms are computed on pixel arrays using discrete Fourier transforms due to their high computational efficiency. However, the mathematics underpinning these algorithms is typically formulated using continuous mathematics, which can result in a loss of spatial resolution in the reconstructed images.

Higher CPAP levels improve functional residual capacity at birth in preterm rabbits.

Background: Preterm infants are commonly supported with 4-8 cm HO continuous positive airway pressures (CPAP), although higher CPAP levels may improve functional residual capacity (FRC).

Methods: Preterm rabbits delivered at 29/32 days (~26-28 weeks human) gestation received 0, 5, 8, 12, 15 cm HO of CPAP or variable CPAP of 15 to 5 or 15 to 8 cm HO (decreasing ~2 cm HO/min) for up to 10 min after birth.

Results: FRC was lower in the 0 (6.

Increasing Respiratory Effort With 100% Oxygen During Resuscitation of Preterm Rabbits at Birth.

Spontaneous breathing is essential for successful non-invasive respiratory support delivered by a facemask at birth. As hypoxia is a potent inhibitor of spontaneous breathing, initiating respiratory support with a high fraction of inspired O may reduce the risk of hypoxia and increase respiratory effort at birth. Preterm rabbit kittens (29 days gestation, term ~32 days) were delivered and randomized to receive continuous positive airway pressure with either 21% ( = 12) or 100% O ( = 8) via a facemask.

Ring artifact suppression in X-ray computed tomography using a simple, pixel-wise response correction.

We present a pixel-specific, measurement-driven correction that effectively reduces errors in detector response that give rise to the ring artifacts commonly seen in X-ray computed tomography (CT) scans. This correction is easy to implement, suppresses CT artifacts significantly, and is effective enough for use with both absorption and phase contrast imaging. It can be used as a standalone correction or in conjunction with existing ring artifact removal algorithms to further improve image quality.

Chaotic Sensing.

We propose a sparse imaging methodology called Chaotic Sensing (ChaoS) that enables the use of limited yet deterministic linear measurements through fractal sampling. A novel fractal in the discrete Fourier transform is introduced that always results in the artefacts being turbulent in nature. These chaotic artefacts have characteristics that are image independent, facilitating their removal through dampening (via image denoising) and obtaining the maximum likelihood solution.

Spiral scanning X-ray fluorescence computed tomography.

Scanning X-ray fluorescence tomography was once considered impractical due to prohibitive measurement time requirements but is now common for investigating metal distributions within small systems. A recent look-ahead to the possibilities of 4-generation synchrotron light sources [J. Synchrotron.

Validation of a Geant4 model of the X-ray fluorescence microprobe at the Australian Synchrotron.

A Geant4 Monte Carlo simulation of the X-ray fluorescence microprobe (XFM) end-station at the Australian Synchrotron has been developed. The simulation is required for optimization of the scan configuration and reconstruction algorithms. As part of the simulation process, a Gaussian beam model was developed.

Annular electron energy-loss spectroscopy in the scanning transmission electron microscope.

We study atomic-resolution annular electron energy-loss spectroscopy (AEELS) in scanning transmission electron microscopy (STEM) imaging with experiments and numerical simulations. In this technique the central part of the bright field disk is blocked by a beam stop, forming an annular entry aperture to the spectrometer. The EELS signal thus arises only from electrons scattered inelastically to angles defined by the aperture.

Texture control in a pseudospin Bose-Einstein condensate.

We describe a wave function engineering approach to the formation of textures in nonrotated multicomponent Bose-Einstein condensates. With numerical simulations of a viable two-component condensate experiment, we demonstrate the formation of a ballistically expanding regular lattice texture, composed of half-quantum vortices and spin-2 textures. The formation is described by a linear interference process in which the geometry and phase of three initially separated wave packets provide deterministic control over the resulting lattice texture.

Phase vortices from a Young's three-pinhole interferometer.

An analysis is presented of the phase vortices generated in the far field by an arbitrary arrangement of three monochromatic point sources of complex spherical waves. In contrast with the case of three interfering plane waves, in which an infinitely extended vortex lattice is generated, the spherical sources generate a finite number of phase vortices. Analytical expressions for the vortex core locations are developed and shown to have a convenient representation in a discrete parameter space.