The use of algorithms to predict surface seawater dimethyl sulphide concentrations in the SE Pacific, a region of steep gradients in primary productivity, biomass and mixed layer depth

Dimethyl sulphide (DMS) is an important precursor of cloud condensation nuclei (CCN), particularly in the remote marine atmosphere. The SE Pacific is consistently covered with a persistent stratocumulus layer that increases the albedo over this large area. It is not certain whether the source of CCN to these clouds is natural and oceanic or anthropogenic and terrestrial. This unknown currently limits our ability to reliably model either the cloud behaviour or the oceanic heat budget of the region. In order to better constrain the marine source of CCN, it is necessary to have an improved understanding of the sea-air flux of DMS. Of the factors that govern the magnitude of this flux, the greatest unknown is the surface seawater DMS concentration. In the study area, there is a paucity of such data, although previous measurements suggest that the concentration can be substantially variable. In order to overcome such data scarcity, a number of climatologies and algorithms have been devised in the last decade to predict seawater DMS. Here we test some of these in the SE Pacific by comparing predictions with measurements of surface seawater made during the Vamos Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) in October and November of 2008. We conclude that none of the existing algorithms reproduce local variability in seawater DMS in this region very well. From these findings, we recommend the best algorithm choice for the SE Pacific and suggest lines of investigation for future work

Climate change and the Great Barrier Reef: a vulnerability assessment

The combination of sensitivity and exposure to climate change render the GBR ecosystem highly vulnerable to climate change. While the components and processes that comprise the ecosystem vary in their vulnerability, the implications of climate change are far-reaching and, in many cases, severe. Overall, the GBR ecosystem has features that will afford it some protection from climate change compared with tropical marine reef ecosystems. These features include its immense size, its location adjacent to a relatively sparsely populated and developed country, and its protection under a management regime that is recognised as the best in the world. However, coral reefs are one of the most vulnerable of all of the earth’s ecosystems to climate change, and the GBR will continue to be affected. Even under the most optimistic climate change scenarios, the GBR is destined for significant change over this century; under pessimistic scenarios, catastrophic impacts are possible. In this section, we provide an overview of the exposure of the GBR to climate factors, including a summary of predicted changes to the GBR climate, followed by a review of the reasons for the sensitivity of the GBR to climate change. We then provide a synopsis of current and emerging knowledge about the vulnerability of GBR species groups and habitats to climate change.This is Chapter 24 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/137 ID: 7

Calibration of a novel microstructural damage model for wire bonds

In a previous paper, a new time-domain damage-based physics model was proposed for the lifetime prediction of wire bond interconnects in power electronic modules. Unlike cycle-dependent life prediction methodologies, this model innovatively incorporates temperature- and time-dependent properties so that rate-sensitive processes associated with the bond degradation can be accurately represented. This paper presents the work on the development and calibration of the damage model by linking its core parameter, i.e., “damage,” to the strain energy density, which is a physically quantifiable materials property. Isothermal uniaxial tensile data for unbonded pure aluminum wires (99.999%) have been used to develop constitutive functions, and the model has been calibrated by the derived values of the strain energy density

Reliability of thick Al wire: a study of the effects of wire bonding parameters on thermal cycling degradation rate using non-destructive methods

The effect of bonding parameters on the reliability of thick Al wire bond is investigated. Samples were prepared with 25 different designs with 5 different bonding parameters such as time, ultrasonic power, begin- force, end-force and touch-down steps (pre-compression) with 5 levels. The bond signals of ultrasonic generator were collected during bonding in order to obtain prior quality information of bonded wires. 3D x-ray tomography was then used to evaluate bond quality during passive thermal cycling between -55 °C and 125 °C. Tomography datasets were obtained from the as-bonded condition and during cycling. The results clearly show ultrasonic power, appropriate levels of begin-force and touch-down steps are all important for achieving a well attached and reliable bond. Analysis of the virtual cross-sections indicates a good correlation between the bond signal (i.e. the initial bond quality) and wire bond damage/ degradation rate. An improved understanding of the wire bonding process was achieved by observing the effect of the complex interaction of bonding parameters on the ultrasonic generator signals and degradation rate under thermal cycling

Climate change and the Great Barrier Reef: a vulnerability assessment

The Great Barrier Reef is renowned internationally for its ecological importance and the beauty of its seascapes and landscapes. These natural values also provide important ecosystem services, which underpin Australian $6.9 billion worth of economic activity and incalculable social values. In combination, the social-ecological system centred on the reef is extraordinary in its importance, and in its complexity. Understanding the vulnerability of such a large and intricate system to climate change is a particularly difficult challenge. A first step in meeting this challenge is to describe the general characteristics of the system and the environment in which they interact. Toward this end, this chapter introduces the Great Barrier Reef and the human systems that interact with it, providing a context for the detailed chapters that follow.This is Chapter 1 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/13

Sub-wavelength diffraction-free imaging with low-loss metal-dielectric multilayers

We demonstrate numerically the diffraction-free propagation of sub-wavelength sized optical beams through simple elements built of metal-dielectric multilayers. The proposed metamaterial consists of silver and a high refractive index dielectric, and is designed using the effective medium theory as strongly anisotropic and impedance matched to air. Further it is characterised with the transfer matrix method, and investigated with FDTD. The diffraction-free behaviour is verified by the analysis of FWHM of PSF in the function of the number of periods. Small reflections, small attenuation, and reduced Fabry Perot resonances make it a flexible diffraction-free material for arbitrarily shaped optical planar elements with sizes of the order of one wavelength.Comment: 5 pages, 4 figure

Effects of Amino Acid and Branched-Chain Volatile Fatty Acid Additions on in Vitro Fermentation of Dormant Range Grasses

Two-stage in vitro fermentation was used to screen five amino acids and three branched-chain volatile fatty acids as potential additions to a grain urea supplement for cows grazing dormant winter range. Urea addition alone increased dry matter and fiber digestibility of dormant cool season grasses. Methionine addition improved fiber digestibility and rate of fermentation of cool season grasses over urea alone. Compared to urea addition, the branched-chain volatile fatty acids did not increase dry matter or fiber disappearance or improve rate of fermentation of dormant range grasses. None of the buffer additions tested or urea increased digestibility of the dormant warm season grasses. This preliminary laboratory study indicates that methionine offers the greatest potential for addition to a grain urea supplement to increase utilization of dormant range grasses

Two-Electron Quantum Dot in Magnetic Field: Analytical Results

Two interacting electrons in a harmonic oscillator potential under the influence of a perpendicular homogeneous magnetic field are considered. Analytic expressions are obtained for the energy spectrum of the two- and three-dimensional cases. Exact conditions for phase transitions due to the electron-electron interaction in a quantum dot as a function of the dot size and magnetic field are calculated.Comment: 22 pages (Latex file), 3 Postscript figures, to be published in Phys. Rev.B 55, N 20 (1997