Frequency-Domain Stochastic Modeling of Stationary Bivariate or Complex-Valued Signals

There are three equivalent ways of representing two jointly observed real-valued signals: as a bivariate vector signal, as a single complex-valued signal, or as two analytic signals known as the rotary components. Each representation has unique advantages depending on the system of interest and the application goals. In this paper we provide a joint framework for all three representations in the context of frequency-domain stochastic modeling. This framework allows us to extend many established statistical procedures for bivariate vector time series to complex-valued and rotary representations. These include procedures for parametrically modeling signal coherence, estimating model parameters using the Whittle likelihood, performing semi-parametric modeling, and choosing between classes of nested models using model choice. We also provide a new method of testing for impropriety in complex-valued signals, which tests for noncircular or anisotropic second-order statistical structure when the signal is represented in the complex plane. Finally, we demonstrate the usefulness of our methodology in capturing the anisotropic structure of signals observed from fluid dynamic simulations of turbulence.Comment: To appear in IEEE Transactions on Signal Processin

Space-based geoengineering: challenges and requirements

The prospect of engineering the Earth's climate (geoengineering) raises a multitude of issues associated with climatology, engineering on macroscopic scales, and indeed the ethics of such ventures. Depending on personal views, such large-scale engineering is either an obvious necessity for the deep future, or yet another example of human conceit. In this article a simple climate model will be used to estimate requirements for engineering the Earth's climate, principally using space-based geoengineering. Active cooling of the climate to mitigate anthropogenic climate change due to a doubling of the carbon dioxide concentration in the Earth's atmosphere is considered. This representative scenario will allow the scale of the engineering challenge to be determined. It will be argued that simple occulting discs at the interior Lagrange point may represent a less complex solution than concepts for highly engineered refracting discs proposed recently. While engineering on macroscopic scales can appear formidable, emerging capabilities may allow such ventures to be seriously considered in the long term. This article is not an exhaustive review of geoengineering, but aims to provide a foretaste of the future opportunities, challenges, and requirements for space-based geoengineering ventures

A Power Variance Test for Nonstationarity in Complex-Valued Signals

We propose a novel algorithm for testing the hypothesis of nonstationarity in complex-valued signals. The implementation uses both the bootstrap and the Fast Fourier Transform such that the algorithm can be efficiently implemented in O(NlogN) time, where N is the length of the observed signal. The test procedure examines the second-order structure and contrasts the observed power variance - i.e. the variability of the instantaneous variance over time - with the expected characteristics of stationary signals generated via the bootstrap method. Our algorithmic procedure is capable of learning different types of nonstationarity, such as jumps or strong sinusoidal components. We illustrate the utility of our test and algorithm through application to turbulent flow data from fluid dynamics

Autologous Chondrocyte Implantation: Scaffold-Based Solutions

Autologous chondrocyte implantation is a surgical technique utilized for repair of articular cartilage defects. The originally described technique for autologous chondrocyte implantation involves applying a liquid suspension of the cultured chondrocytes to a cartilage defect and sealing the defect with a periosteum or collagen patch. Scaffolds for housing chondrocytes were introduced to allow for increased ease of delivery and application, to avoid leakage of chondrocytes out of the defect, and to allow for an implant that more closely mimics the non-uniform tissue architecture of healthy articular cartilage. In this chapter we describe the design, clinical outcomes, and commercial availability of various scaffolds reported in the clinical literature for autologous chondrocyte implantation

Evolution of pulmonary inflammation and nutritional status in infants and young children with cystic fibrosis

Introduction Improved nutrition is the major proven benefit of newborn screening programmes for cystic fibrosis (CF) and is associated with better clinical outcomes. It was hypothesised that early pulmonary inflammation and infection in infants with CF is associated with worse nutrition. Methods Weight, height and pulmonary inflammation and infection in bronchoalveolar lavage (BAL) were assessed shortly after diagnosis in infants with CF and again at 1, 2 and 3 years of age. Body mass index (BMI) was expressed as z-scores. Inflammatory cells and cytokines (interleukin 1b (IL-1b), IL-6, IL-8 and tumour necrosis factor a (TNFa)), free neutrophil elastase activity and myeloperoxidase were measured in BAL. Mixed effects modelling was used to assess longitudinal associations between pulmonary inflammation, pulmonary infection (Staphylococcus aureus and Pseudomonas aeruginosa) and BMI z-score after adjusting for potential confounding factors. Results Forty-two infants were studied (16 (38%) male; 39 (93%) pancreatic insufficient); 36 were diagnosed by newborn screening (at median age 4 weeks) and six by early clinical diagnosis (meconium ileus). Thirty-one (74%) received antistaphylococcal antibiotics. More than two-thirds were asymptomatic at each assessment. Mean BMI z-scores wer

Theoretical and Experimental Investigation of Heat Conduction in Air, Including Effects of Oxygen Dissociation

Solutions are presented for the conduction of beat through a semi-infinite gas medium having a uniform initial temperature and a constant boundary temperature. The coefficients of thermal conductivity and diffusivity are treated as variables, and the solutions are extended to the case of air at temperatures where oxygen dissociation occurs. These solutions are used together with shock-tube measurements to evaluate the integral of thermal conductivity for air as a function of temperature

Estimating the Economic Value of Australian Stock Herding Dogs

This study aimed to estimate the value of the typical Australian herding dog in terms of predicted return on investment. This required an assessment of the costs associated with owning herding dogs and estimation of the work they typically perform. Data on a total of 4,027 dogs were acquired through The Farm Dog Survey which gathered information from 812 herding dog owners around Australia. The median cost involved in owning a herding dog was estimated to be a total of AU$7,763 over the period of its working life. The work performed by the dog throughout this time was estimated to have a median value of AU$40,000. So, herding dogs typically provided their owners with a 5.2-fold return on investment. When respondents were asked to nominate the maximal, one-off, veterinary expenditure they would consider to remedy an illness or injury for an especially valued dog, the median response was AU$1,001–2,000 which is not concordant with the dogs’ calculated median lifetime value. The current findings equip working dog owners with useful information to make financially appropriate expenditure decisions related to their working dogs. This is expected to increase farm profitability and improve welfare for farm dogs

Valuable Behavioural Phenotypes in Australian Farm Dogs

This report presents findings regarding the ways to optimise the performance of livestock working dogs in Australia. The methods available to optimise dog performance include both environmental and genetic factors. The objectives of this study were to identify objective measures of desirable behavioural phenotypes in Australian livestock working dogs and explore genetic parameters of these \u27quality of working life\u27 traits within the Kelpie breed. The document reports on genotyping that reveals gene-behaviour associations and describes heritability estimates that underpin a database for potential estimated breeding value (EBV) calculations

Valuable Behavioural Phenotypes in Australian Farm Dogs

This report presents findings regarding the ways to optimise the performance of livestock working dogs in Australia. The methods available to optimise dog performance include both environmental and genetic factors. The objectives of this study were to identify objective measures of desirable behavioural phenotypes in Australian livestock working dogs and explore genetic parameters of these \u27quality of working life\u27 traits within the Kelpie breed. The document reports on genotyping that reveals gene-behaviour associations and describes heritability estimates that underpin a database for potential estimated breeding value (EBV) calculations

Estimating the Economic Value of Australian Stock Herding Dogs

This study aimed to estimate the value of the typical Australian herding dog in terms of predicted return on investment. This required an assessment of the costs associated with owning herding dogs and estimation of the work they typically perform. Data on a total of 4,027 dogs were acquired through The Farm Dog Survey which gathered information from 812 herding dog owners around Australia. The median cost involved in owning a herding dog was estimated to be a total of AU$7,763 over the period of its working life. The work performed by the dog throughout this time was estimated to have a median value of AU$40,000. So, herding dogs typically provided their owners with a 5.2-fold return on investment. When respondents were asked to nominate the maximal, one-off, veterinary expenditure they would consider to remedy an illness or injury for an especially valued dog, the median response was AU$1,001–2,000 which is not concordant with the dogs’ calculated median lifetime value. The current findings equip working dog owners with useful information to make financially appropriate expenditure decisions related to their working dogs. This is expected to increase farm profitability and improve welfare for farm dogs