Atmosphere-Ocean Ozone Exchange – A Global Modeling Study of Biogeochemical, Atmospheric and Water-Side Turbulence Dependencies

The significance of the removal of tropospheric ozone by the oceans, covering ~2/3 of the Earth's surface, has only been addressed in a few studies involving water tank, aircraft, and tower flux measurements. On the basis of results from these few observations of the ozone dry deposition velocity (VdO3), atmospheric chemistry models generally apply an empirical, constant ocean uptake rate of 0.05 cm s-1. This value is substantially smaller than the atmospheric turbulent transport velocity for ozone. On the other hand, the uptake is higher than expected from the solubility of ozone in clean water alone, suggesting that there is an enhancement in oceanic ozone uptake, e.g., through a chemical destruction mechanism. We present an evaluation of a global-scale analysis with a new mechanistic representation of atmosphere-ocean ozone exchange. The applied atmosphere chemistry-climate model includes not only atmospheric but also waterside turbulence and the role of waterside chemical loss processes as a function of oceanic biogeochemistry. The simulations suggest a larger role of biogeochemistry in tropical and subtropical ozone oceanic uptake with a relative small temporal variability, whereas in midlatitude and high-latitude regions, highly variable ozone uptake rates are expected because of the stronger influence of waterside turbulence. Despite a relatively large range in the explicitly calculated ocean uptake rate, there is a surprisingly small sensitivity of simulated Marine Boundary Layer ozone concentrations compared to the sensitivity for the commonly applied constant ocean uptake approach. This small sensitivity points at compensating effects through inclusion of the process-based ocean uptake mechanisms to consider variability in oceanic O3 deposition consistent with that in atmospheric and oceanic physical, chemical, and biological processe

Elemental bio-imaging : in situ analysis of trace elements in tissue by laser ablation-inductively coupled plasma-mass spectrometry

University of Technology, Sydney. Faculty of Science.Elemental bio-imaging is a new application of laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS) that determines in situ trace element concentrations in thin sections of biological tissues. This project developed a LA-ICP-MS method for creating colour images of the regional distribution of both metals and non-metals in a variety of biological samples. The developed method was capable of producing images with a lateral resolution as low as 30 µm. This was achieved using a 30 µm laser spot that was rastered across the sample at a rate of 30 µm s⁻¹. It was found that a laser fluence of 0.22-0.28 J cm⁻² was best suited for soft tissue sections with minimal particle redeposition and fracturing of the surrounding sample. Evaluation of the octopole reaction system (ORS) fitted to the Agilent 7500 ce instrument found that the use of a collision gas for interference removal was inadvisable for imaging experiments. Experiments were carried out to determine the significance of potential polyatomic interferences in the ablation of tissue. It was found that the 'dry' nature of the plasma in LA-ICP-MS significantly reduced the occurrence of O and H based polyatomics, and the small sample load in each ablation reduced the effect of other matrix-based interferences on elements in the mg kg⁻¹ concentration range. Application of the method to sections of human lymph nodes impregnated with malignant melanoma found imaging of ³¹P was able to accurately discern healthy cells from cancerous tissue. Measurement of the ratio between ³¹P and other elements improved the contrast between the two types of cells. Three-dimensional models of imaged lymph nodes further improved the distinction between the melanoma cells and normal tissue. A method was developed for producing matrix-matched tissue standards by homogenising chicken tissue with known amounts of added elemental standards. Digestion of the tissue standards was performed and analysis by solution nebulisation ICP-MS confirmed the concentration of each added element. The standards were frozen and cut to the desired thickness for ablation and construction of multi-point calibration curves. An Fe-fed mouse model for Parkinson's disease (PD) was used to demonstrate the characteristics of the technique. C57BL6 mice were fed a diet high in Fe during development and were treated with both clioquinol (CQ) and L-DOPA, both of which are thought to chelate Fe in the brain. Results showed a decrease in Fe in the treated animals within the region of the brain called the substantia nigra (SN), which is adversely affected in PD. A 6-hydroxydopamine (6-OHDA) model for PD was also examined. 6-OHDA is directly injected into the rodent brain, stimulating the loss of cells within the SN. Imaging of sections taken from 6-OHDA lesioned animals showed a significant increase in Fe within the SN bilaterally when compared to control animals. In summary, elemental bio-imaging is a new method that can be applied to tissue sections from many sources, including humans. The technique has the potential to assist biologists in identifying possible new biomarkers for disease, related specifically to trace elements

Extremal sequences of polynomial complexity

The joint spectral radius of a bounded set of $d \times d$ real matrices is defined to be the maximum possible exponential growth rate of products of matrices drawn from that set. For a fixed set of matrices, a sequence of matrices drawn from that set is called \emph{extremal} if the associated sequence of partial products achieves this maximal rate of growth. An influential conjecture of J. Lagarias and Y. Wang asked whether every finite set of matrices admits an extremal sequence which is periodic. This is equivalent to the assertion that every finite set of matrices admits an extremal sequence with bounded subword complexity. Counterexamples were subsequently constructed which have the property that every extremal sequence has at least linear subword complexity. In this paper we extend this result to show that for each integer $p \geq 1$, there exists a pair of square matrices of dimension $2^p(2^{p+1}-1)$ for which every extremal sequence has subword complexity at least $2^{-p^2}n^p$.Comment: 15 page

Activity Identification and Local Linear Convergence of Douglas--Rachford/ADMM under Partial Smoothness

Convex optimization has become ubiquitous in most quantitative disciplines of science, including variational image processing. Proximal splitting algorithms are becoming popular to solve such structured convex optimization problems. Within this class of algorithms, Douglas--Rachford (DR) and alternating direction method of multipliers (ADMM) are designed to minimize the sum of two proper lower semi-continuous convex functions whose proximity operators are easy to compute. The goal of this work is to understand the local convergence behaviour of DR (resp. ADMM) when the involved functions (resp. their Legendre-Fenchel conjugates) are moreover partly smooth. More precisely, when both of the two functions (resp. their conjugates) are partly smooth relative to their respective manifolds, we show that DR (resp. ADMM) identifies these manifolds in finite time. Moreover, when these manifolds are affine or linear, we prove that DR/ADMM is locally linearly convergent. When $J$ and $G$ are locally polyhedral, we show that the optimal convergence radius is given in terms of the cosine of the Friedrichs angle between the tangent spaces of the identified manifolds. This is illustrated by several concrete examples and supported by numerical experiments.Comment: 17 pages, 1 figure, published in the proceedings of the Fifth International Conference on Scale Space and Variational Methods in Computer Visio

A Study of the Actuarial Profession

The aim of this thesis is to educate the reader about the career of an actuary and will put into practice some of the rigorous mathematical applications that are used. There will also be an emphasis on the financial and business applications of the previous information, which encompasses the well roundedness of the profession. The actuarial profession is ranked one of the best in the country and rightfully so because of the skill and time it takes to perform it well. This thesis will guide the reader in understanding more clearly the high rank of the actuarial profession and the details of the statistical mathematics that are used

Movement disorders and syndromic autism: a systematic review

Movement disorders are reported in idiopathic autism but the extent to which comparable movement disorders are found in syndromic/co-morbid autism is unknown. A systematic search of Medline, Embase, PsychINFO and CINAHL on the prevalence of specific movement disorder in syndromic autism associated with specific genetic syndromes identified 16 papers, all relating to Angelman syndrome or Rett syndrome. Prevalence rates of 72.7–100% and 25.0–27.3% were reported for ataxia and tremor, respectively, in Angelman syndrome. In Rett syndrome, prevalence rates of 43.6–50% were reported for ataxia and 27.3–48.3% for tremor with additional reports of dystonia, rigidity and pyramidal signs. However, reliable assessment measures were rarely used and recruitment was often not described in sufficient detail

Psychopathy and the DSM-IV criteria for antisocial personality disorder.

The Axis II Work Group of the Task Force on Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) has expressed concern that antisocial personality disorder (APD) criteria are too long and cumbersome and that they focus on antisocial behaviors rather than personality traits central to traditional conceptions of psychopathy and to international criteria. R. D. Hare et al describe an alternative to the approach taken in the DSM-III—Revised (DSM-III—R; American Psychiatric Association, 1987), namely, the revised Psychopathy Checklist. The authors also discuss the multisite APD field trials designed to evaluate and compare 4 criteria sets: the DSM-III—R criteria, a shortened list of these criteria, the criteria for dyssocial personality disorder from the 10th edition of the International Classification of Diseases (World Health Organization, 1990), and a 10-item criteria set for psychopathic personality disorder derived from the revised Psychopathy Checklist. (PsycINFO Database Record (c) 2015 APA, all rights reserved

Elemental bio-imaging of trace elements in teeth using laser ablation-inductively coupled plasma-mass spectrometry

Objectives: In this study we present the application of a novel laboratory method that employs laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to construct two-dimensional maps of trace elements in teeth. Methods: Teeth were sectioned longitudinally, embedded in resin and polished to a smooth surface. Data were generated by laser ablating the entire sectioned tooth surface. Elemental images were constructed using custom-built software. Results: Quantified images of 66Zn, 88Sr, 111Cd and 208Pb, with a spatial resolution of 30 μm2, were generated from three teeth. Concentrations were determined by single-point calibration against NIST SRM 1486 (bone meal). Zn and Sr concentrations were determined in the μg g-1 range and Cd and Pb in the ng g -1 range. Concentrations of Pb, Zn and Cd were higher in dentine particularly in regions adjacent the pulp. Conclusions: Elemental bio-imaging employing LA-ICP-MS is a novel method for constructing μm-scale maps of trace elements in teeth. This simple imaging method displays the heterogeneity of trace elements throughout the tooth structure that correspond to specific structural and developmental features of teeth. As a preliminary study, this work demonstrates the capabilities of LA-ICP-MS imaging in dental research. © 2011 Elsevier Ltd. All rights reserved