Showing papers by "University of Sydney published in 1992"

C4.5: Programs for Machine Learning

Abstract: From the Publisher: Classifier systems play a major role in machine learning and knowledge-based systems, and Ross Quinlan's work on ID3 and C4.5 is widely acknowledged to have made some of the most significant contributions to their development. This book is a complete guide to the C4.5 system as implemented in C for the UNIX environment. It contains a comprehensive guide to the system's use , the source code (about 8,800 lines), and implementation notes. The source code and sample datasets are also available on a 3.5-inch floppy diskette for a Sun workstation. C4.5 starts with large sets of cases belonging to known classes. The cases, described by any mixture of nominal and numeric properties, are scrutinized for patterns that allow the classes to be reliably discriminated. These patterns are then expressed as models, in the form of decision trees or sets of if-then rules, that can be used to classify new cases, with emphasis on making the models understandable as well as accurate. The system has been applied successfully to tasks involving tens of thousands of cases described by hundreds of properties. The book starts from simple core learning methods and shows how they can be elaborated and extended to deal with typical problems such as missing data and over hitting. Advantages and disadvantages of the C4.5 approach are discussed and illustrated with several case studies. This book and software should be of interest to developers of classification-based intelligent systems and to students in machine learning and expert systems courses.

Recent Developments in Expressed Emotion and Schizophrenia

Abstract: Expressed emotion (EE) has substantial scientific support as a predictor of relapse of positive symptoms. The median relapse rate in a high-EE environment is 48%, compared with 21% in a low-EE environment. This effect does not seem to be due to confounding with other variables, but it is subject to limitations in its scope of application. EE probably determines relapse through its effect on emotions and symptom control. A stress-vulnerability model of relapse is advanced that incorporates biological factors as well as cycles of mutual influence between symptomatic behaviour, life events, and EE. Aversive types of behaviour in patients and their relatives are seen as understandable reactions to stress that are moderated by social perceptions and coping skills. Families have made positive achievements, including the provision of non-invasive support.

Recent developments in expressed emotion and schizophrenia.

Abstract: Reviews outcome studies on the course of schizophrenia as predicted by expressed emotion (EE) and considers methodological issues. The nature of EE and the mechanism for the predictive results are explored. EE probably determines relapse through its effect on emotions and symptom control. A stress-vulnerability model of relapse is advanced that incorporates biological factors and cycles of mutual influence between symptomatic behavior, life events, and EE. A social interaction model of schizophrenia may help to alleviate concerns that EE represents an attempt to blame families for schizophrenic relapse. Aversive types of behavior in patients and their relatives are seen as understandable reactions to stress that are moderated by social perceptions and coping skills. Families have made positive achievements, including the provision of noninvasive support.

Anti‐nutritive effect of wheat pentosans in broiler chickens: Roles of viscosity and gut microflora

Abstract: 1 The mechanism of the anti-nutritive activity of isolated wheat pentosans was investigated by examining the roles of digesta viscosity and gut microflora in broiler chickens 2 Wheat pentosans were isolated by alkaline extraction and purified by sequential treatment with pancreatin, alpha-amylase and lichenase, and high-speed centrifugation Some of the pentosans were depolymerised using a beta-xylanase, which reduced the relative viscosity of the polysaccharides 4 fold 3 Inclusion of 35 g alkali-extractable pentosans (containing 854 g arabinoxylans/kg DM) per kg diet significantly (P less than 005) depressed broiler performance and the viscosity of the digesta of these birds was significantly (P less than 005) higher than that of controls Addition of the same amount of depolymerised pentosans had no significant effect on bird performance and had less effect on digesta viscosity 4 Supplementation of the diet containing wheat pentosans (30 g/kg) with procaine penicillin (150 mg/kg) did not improve bird performance 4 It is concluded that the wheat pentosans elicit their anti-nutritive activity predominantly through increasing the viscosity of digesta

Why do female adders copulate so frequently

Abstract: MALES of most animal species will enhance their reproductive success if they mate often and with many different partners, whereas promiscuous mating is unlikely to increase a female's reproductive success. Why then is multiple copulation by females so common1–6? Many theoreticians have suggested that multiple copulations might enhance the viability of a female's offspring, either because of inadequate quantities of sperm from the first mating1,7, additional nutrients derived from the seminal fluid7,8 or some genetic advantage9–14. Our field studies on Swedish adders provide the first empirical evidence that multiple copulations, with different partners each time, increase offspring viability. This advantage apparently results from more intense sperm competition in the female's reproductive tract, resulting in a higher proportion of her ova being fertilized by genetically superior males.

The emotional motor system.

Abstract: A large number of new descending motor pathways to caudal brainstem and spinal cord have been recognized recently. Nevertheless all the new pathways seem to belong to one of three motor systems in the central nervous system (CNS). This survey gives an overview of the pathways belonging to the so-called emotional motor system or the third motor system as defined by Holstege. The similarities and differences with the core, median and lateral paracore areas of the CNS as defined by Nieuwenhuys are discussed.

The inhibition of nutrient digestion by wheat pentosans

Abstract: Two pentosan-rich fractions (water-extractable, WEP, and alkali-extractable, AEP) were isolated from a wheat milling by-product. When both WEP and AEP were added to a commercial-type broiler diet the apparent metabolizable energy (AME), nitrogen retention, feed utilization and growth of broilers were significantly (P less than 0.001) depressed. These depressions were closely correlated (P less than 0.001) to the level of pentosans in the diets. At the highest level of inclusion of pentosans (equivalent to 40 g arabinoxylans as AEP/kg) the ileal digestibilities of starch, protein and lipid were decreased by 14.6, 18.7 and 25.8% respectively.

Toward a definition of asthma for epidemiology.

Abstract: Because there is no “gold standard” for defining asthma for epidemiology, we have defined current asthma as bronchial hyperresponslveness (BHR) plus recent wheeze (in the 12 months prior to study). To describe the characteristics of groups categorized by these measurements, we studied two samples of children aged 7 to 12 yr: 210 from a population sample and 142 self-identified asthmatics. Bronchial responsiveness to histamine was measured by the rapid method, respiratory symptom history, and asthma medication use by self-administered questionnaire to parents and atopy by skin prick tests to 14 allergens. Children recorded daily Airflometer readings and symptom scores for 2 wk. Children with current asthma had more severe bronchial responsiveness, greater Airflometer variability, more symptoms, more atopy (particularly to house dust mites), and used more asthma medication than children with BHR or recent wheeze alone. Children with BHR, but not with recent wheeze, were intermediate between the current asth...

The epidemiology of fractures and fracture-dislocations of the cervical spine.

Abstract: A total of 717 fractures and fracture-dislocations of the cervical spine occurred in 657 patients in a 13-year period. Injury was commonest in the third decade of life. The levels most frequently injured were the second, fifth, and sixth. Injuries of the first and second cervical vertebrae commonly occurred together, and injuries involving the upper and lower cervical spine in the same individual occurred in 9 per cent of patients with fractures of C1 and C2. Odontoid fractures were the most frequent fractures in patients over 70 years of age, and formed the majority of fractures in patients over 80 years of age. It is recommended that if a fracture of the upper cervical spine is seen on radiographs, another fracture in the upper or lower cervical spine should be excluded. Patients aged 70 years and above who complain of neck pain after trauma should be suspected of having an odontoid fracture, until proven otherwise.

Comparison of cognitive-behavioral group treatment and an alternative non-psychological treatment for chronic low back pain.

Abstract: This study was designed to investigate the relative efficacy of cognitive-behavioral group treatment, including relaxation training, in comparison with a control condition in a sample of 20 outpatients with chronic low back pain. Subjects in both conditions also received the same physiotherapy back-education and exercise program. The control condition included a control for the attention of the therapist in the cognitive-behavioral treatment. The combined psychological treatment and physiotherapy condition displayed significantly greater improvement than the attention-control and physiotherapy condition at post-treatment on measures of other-rated functional impairment, use of active coping strategies, self-efficacy beliefs, and medication use. These differences were maintained at 6 month follow-up on use of active coping strategies and, to a lesser degree, on self-efficacy beliefs and other-rated functional impairment.

The peripheral myelin gene PMP-22/GAS-3 is duplicated in Charcot-Marie-Tooth disease type 1A.

Abstract: Charcot-Marie-Tooth disease type 1A (CMT1A) is associated with a DNA duplication at chromosome 17p11.2. In view of the point mutation in the gene for peripheral myelin protein pmp-22/gas-3 in Trembler mice, a murine model for CMT1A, we have analysed whether this gene is altered in CMT1A. Here we show that the human homologue of the murine pmp-22 gene is located within the CMT1A DNA duplication, which is a direct repeat and does not interrupt the coding region of PMP-22. Expression of PMP-22 in CMT1A fibroblasts is similar to expression in control fibroblasts. Increased gene dosage or altered PMP-22 expression in the peripheral nervous system are therefore possible mechanisms by which PMP-22 is involved in CMT1A.

Insulin-like growth factor II acts through an endogenous growth pathway regulated by imprinting in early mouse embryos.

Abstract: We present evidence that insulin-like growth factor II (IGF-II) mediates growth in early mouse embryos and forms a pathway in which imprinted genes influence development during preimplantation stages. mRNA and protein for IGF-II were expressed in preimplantation mouse embryos, but the related factors IGF-I and insulin were not. IGF-I and insulin receptors and the IGF-II/mannose-6-phosphate receptor were expressed. Exogenous IGF-II or IGF-I increased the cell number in cultured blastocysts, but a mutant form of IGF-II that strongly binds only the IGF-II receptor did not. Reduction of IGF-II expression by antisense IGF-II oligonucleotides decreased the rate of progression to the blastocyst stage and decreased the cell number in blastocysts. Preimplantation parthenogenetic mouse embryos expressed mRNA for the IGF-II receptor but not for either IGF-II ligand or the IGF-I receptor, indicating that the latter genes are not expressed when inherited maternally. These data imply that some growth factors and receptors, regulated by genomic imprinting, may control cell proliferation from the earliest stages of embryonic development.

A continuum approach to soil classification by modified fuzzy k‐means with extragrades

Abstract: SUMMARY The need for a more continuous approach to soil classification is discussed, and methods based on the mathematical constructs known as fuzzy sets are considered most appropriate for this. A centroidal grouping method, fuzzy k-means with extragrades, which quantifies the intragrading and extragrading of soil individuals is described. An example of the application of this technique to an area of 4800 ha at Wesepe in The Netherlands is presented. The results show that the technique could create a classification that reflects the main pedological features of the area in a continuous way. Although there may be problems in selecting the optimal number of groups and degree of fuzziness, we conclude that the method is most promising and worthy of consideration when any type of quantitative soil classification is required.

Weight perturbation: an optimal architecture and learning technique for analog VLSI feedforward and recurrent multilayer networks

Abstract: Previous work on analog VLSI implementation of multilayer perceptrons with on-chip learning has mainly targeted the implementation of algorithms such as back-propagation. Although back-propagation is efficient, its implementation in analog VLSI requires excessive computational hardware. It is shown that using gradient descent with direct approximation of the gradient instead of back-propagation is more economical for parallel analog implementations. It is shown that this technique (which is called 'weight perturbation') is suitable for multilayer recurrent networks as well. A discrete level analog implementation showing the training of an XOR network as an example is presented. >

The complexity of multiway cuts (extended abstract)

Abstract: In the Multiway Cut problem we are given an edge-weighted graph and a subset of the vertices called terminals, and asked for a minimum weight set of edges that separates each terminal from all the others. When the number k of terminals is two, this is simply the min-cut, max-flow problem, and can be solved in polynomial time. We show that the problem becomes NP-hard as soon as k = 3, but can be solved in polynomial time for planar graphs for any fixed k. The planar problem is NP-hard, however, if k is not fixed. We also describe a simple approximation algorithm for arbitrary graphs that is guaranteed to come within a factor of 2–2/k of the optimal cut weight.

Patterns of Survival, Growth, and Maturation in Snakes and Lizards

Abstract: We review published data to determine whether squamate reptiles show a specific series of quantitative relationships among life-history characteristics, as predicted by mathematical models and obse...

Nasal mask for CPAP having ballooning/moulding seal with wearer's nose and facial contours

Abstract: A nasal mask which is suitable for use in a continuous positive airway pressure system. The mask has a face contacting portion mounted to a shell which is sized and shaped to overfit the nose region of an intended wearer, and the face contacting portion is in the form of a distendable membrane which is moulded from an elastic plastics material. The distendable membrane and the shell together define a chamber, and pressurised gas admitted to the chamber causes the membrane to distend outwardly from the shell. When placed in contact with the face of the wearer, the distendable membrane is caused to overlay the covered facial regions and, under the influence of the pressurised gas, to conform three-dimensionally with the contours of the overlayed regions. An orifice is formed within the membrane and is shaped and positioned to admit gas from the chamber to the nasal passages of the wearer.

World Bank Financing of Education: Lending, Learning and Development

Abstract: Based on detailed analysis of thousands of confidential World Bank documents, this book demonstrates that the World Bank lies at the centre of the major changes in global education of our time. It outlines the evolution of World Bank lending policies in education, and assesses the policy impact of the Bank's educational projects, looking at how it has: * shaped the economic and social policies of many governments, including policies that affect education * been an influential proponent of the rapid expansion of formal education systems around the world, financing much of that expansion * been instrumental in forging those policies that see education as a precursor to modernisation * served as a major purveyor of Western ideas about how education and the economy are, or should be, related. Following on from the success of the first edition, this revised edition covers topical issues of globalisation and looks into the political debate concerning aid to developing countries. It will be of enormous value to those studying, or working in, educational policy in developing countries, international organisations and financial institutions, and aid agencies.

Fracture energy and fracture process zone

Abstract: The fracture energy Gf can be determined following a RILEM recommendation. However, it has been found that fracture energy depends on both size and geometry of the test specimen. The underlying fictitious crack model postulates that fracture energy, tensile strength, the critical opening of the fictitious crack, and the shape of the softening curve (softening factor) are constants for a given type of concrete. Here it is shown that a local fracture energy ccan be introduced. This local fracture energy varies with the width of the fracture process zone. As the crack approaches the back end of a specimen the fracture process zone becomes more and more confined and hence the local fracture energy decreases. Theoretical predictions are compared with experimental results obtained with the wedge splitting technique described earlier. It is shown that a local variation of the fracture energy leads to a size dependence of the global specific fracture energy.

Factors associated with bronchial hyperresponsiveness in Australian adults and children.

Abstract: To accurately assess putative risk factors for bronchial hyperresponsiveness (BHR), we have used multivariate models to analyse data from 4,366 children living in four regions and from 878 adults. A standard protocol was used to measure bronchial responsiveness to histamine. The prevalence of BHR was high at 7-9 yrs (16-18%), decreased significantly at 11-14 yrs (7-8%), and then increased in adults (12-14%). Atopy was the most important risk factor for BHR at all ages. In children, parental asthma, early respiratory illness and being born in Australia also had a significant influence, and eating fish more than once a week had a protective effect. No effect of parental smoking, gender or race was found. In adults, BHR was associated with being female and with smoking history. It appears that many factors have a significant influence on the presence of BHR, with environmental factors, particularly atopy, birthplace and diet, being the most important.

Characteristics of the Inflammation in Biopsies from Large Airways of Subjects with Asthma and Subjects with Chronic Airflow Limitation

Abstract: Although the characteristics of the histopathologic changes present in subjects who die with status asthmaticus are well documented, the structural changes present in subjects with mild to moderately severe asthma are not well described and the inflammatory changes in the large airways of subjects with chronic airflow limitation (CAL) and asthma have not been compared. Ten subjects with asthma, five taking inhaled corticosteroids and five taking β2-agonist aerosols, five subjects with CAL, and four subjects with no respiratory illness had four biopsies taken from airways 10 mm in diameter. The length of intact epithelium, thickness of basement membrane, and number of lymphocytes, neutrophils, eosinophils, plasma cells, monocytes, and mast cells in the lamina propria, bronchial smooth muscle, and submucosa were measured. Intact epithelium was present along 56% of the basement membrane in the asthmatic subjects, along 54% in the subjects with CAL, and along 84% in the control subjects. In the asthmatic subj...

Grain-Size-Dependent Transformation Behavior in Polycrystalline Tetragonal Zirconia

Abstract: In this paper experimental observations of the tetragonal phase transformation behavior in polycrystalline zirconias and the related toughening contribution are presented. An analysis which considers transformation thermodynamics and residual stresses is developed to describe the influence of grain size on tetragonal-to-monoclinic transformation temperature. The model is based on the promotion of the transformation by local internal tensile stress concentrations whose effects scale with grain size. The analysis is supported by observations of the martensite start temperature---grain size behavior in polycrystalline tetragonal zirconia containing 12 mol% ceria (12 CeTZP). Next, the analysis considers the grain-size-dependent behavior of the transformation-toughening contribution, {Delta}K{sup T}, and the transformation zone size, r{sup T}.

Evolution of sex determination and the Y chromosome: SRY -related sequences in marsupials

Abstract: IN mammals, testis determination is under the control of the testis-determining factor borne by the Y chromosome1,2. SRY, a gene cloned from the sex-determining region of the human Y chromosome, has been equated with the testis-determining factor in man3–5 and mouse6,7. We have used a human SRY probe to identify and clone related genes from the Y chromosome of two marsupial species. Comparisons of eutherian and metatherian Y-located SRY sequences suggest rapid evolution of these genes, especially outside the region encoding the DNA-binding HMG box. The SRY homologues, together with the mouse Ubely homologues8, are the first genes to be identified on the marsupial Y chromosome.