Showing papers by "University of Adelaide published in 2000"

Neural networks for the prediction and forecasting of water resources variables: a review of modelling issues and applications

Abstract: Artificial Neural Networks (ANNs) are being used increasingly to predict and forecast water resources variables. In this paper, the steps that should be followed in the development of such models are outlined. These include the choice of performance criteria, the division and pre-processing of the available data, the determination of appropriate model inputs and network architecture, optimisation of the connection weights (training) and model validation. The options available to modellers at each of these steps are discussed and the issues that should be considered are highlighted. A review of 43 papers dealing with the use of neural network models for the prediction and forecasting of water resources variables is undertaken in terms of the modelling process adopted. In all but two of the papers reviewed, feedforward networks are used. The vast majority of these networks are trained using the backpropagation algorithm. Issues in relation to the optimal division of the available data, data pre-processing and the choice of appropriate model inputs are seldom considered. In addition, the process of choosing appropriate stopping criteria and optimising network geometry and internal network parameters is generally described poorly or carried out inadequately. All of the above factors can result in non-optimal model performance and an inability to draw meaningful comparisons between different models. Future research efforts should be directed towards the development of guidelines which assist with the development of ANN models and the choice of when ANNs should be used in preference to alternative approaches, the assessment of methods for extracting the knowledge that is contained in the connection weights of trained ANNs and the incorporation of uncertainty into ANN models.

Angiopoietin-1 Is an Antipermeability and Anti-Inflammatory Agent In Vitro and Targets Cell Junctions

Abstract: Inflammation is a basic pathological mechanism that underlies many diseases. An important component of the inflammatory response is the passage of plasma components and leukocytes from the blood vessel into the tissues. The endothelial monolayer lining blood vessels reacts to stimuli such as thrombin or vascular endothelial growth factor by changes in cell-cell junctions, an increase in permeability, and the leakage of plasma components into tissues. Other stimuli, such as tumor necrosis factor-alpha (TNF-alpha), are responsible for stimulating the transmigration of leukocytes. Here we show that angiopoietin-1, a cytokine essential in fetal angiogenesis, not only supports the localization of proteins such as platelet endothelial cell adhesion molecule-1 (PECAM-1) into junctions between endothelial cells and decreases the phosphorylation of PECAM-1 and vascular endothelial cadherin, but it also strengthens these junctions, as evidenced by a decrease in basal permeability and inhibition of permeability responses to thrombin and vascular endothelial growth factor. Furthermore, angiopoietin-1 inhibits TNF-alpha-stimulated leukocyte transmigration. Angiopoietin-1 may thus have a major role in maintaining the integrity of endothelial monolayers.

Evolutionary Computation 2 : Advanced Algorithms and Operators

Abstract: Evolutionary Computation 2: Advanced Algorithms and Operators expands upon the basic ideas underlying evolutionary algorithms. The focus is on fitness evaluation, constraint-handling techniques, population structures, advanced techniques in evolutionary computation, and the implementation of evolutionary algorithms. It is intended to be used by individual researchers and students in the expanding field of evolutionary computation.

Soil testing for heavy metals.

Abstract: Soil testing for metal contaminants is a continually evolving process aimed at improving the assessment of environmental and human health hazards associated with heavy metals in soils and plants. A number of challenges present themselves before accurate, reliable and precise contaminant hazard assessment criteria for soils and plants can be made. These include: sampling, extraction and analytical obstacles associated with the determination of trace levels of metals in environmental media; quality assurance and quality control issues associated with both extraction and analytical procedures (especially for metals where non‐compliance with regulatory standards may be penalised); and confounding environmental effects (e.g. rooting depth, soil salinity, Eh, pH, plant species, metal species) which limit the usefulness of the relationship between the current tests and actual hazards. These difficulties have combined to produce soil tests for heavy metals often poorly correlated with hazardwhether this ...

Changes in muscle responses to stimulation of the motor cortex induced by peripheral nerve stimulation in human subjects.

Abstract: The aim of this study was to determine whether prolonged, repetitive mixed nerve stimulation (duty cycle 1 s, 500 ms on-500 ms off, 10 Hz) of the ulnar nerve leads to a change in excitability of primary motor cortex in normal human subjects. Motor-evoked potentials (MEPs) generated in three intrinsic hand muscles [abductor digiti minimi (ADM), first dorsal interosseous (FDI) and abductor pollicis brevis (APB)] by focal transcranial magnetic stimulation were recorded during complete relaxation before and after a period of prolonged repetitive ulnar nerve stimulation at the wrist. Transcranial magnetic stimuli were applied at seven scalp sites separated by 1 cm: the optimal scalp site for eliciting MEPs in the target muscle (FDI), three sites medial to the optimal site and three sites lateral to the optimal stimulation site. The area of the MEPs evoked in the ulnar-(FDI, ADM) but not the median-innervated (APB) muscles was increased after prolonged ulnar nerve stimulation. Centre of gravity measures demonstrated that there was no significant difference in the distribution of cortical excitability after the peripheral stimulation. F-wave responses in the intrinsic hand muscles were not altered after prolonged ulnar nerve stimulation, suggesting that the changes in MEP areas were not the result of stimulus-induced increases in the excitability of spinal motoneurones. Control experiments employing transcranial electric stimulation provided no evidence for a spinal origin for the excitability changes. These results demonstrate that in normal human subjects the excitability of the cortical projection to hand muscles can be altered in a manner determined by the peripheral stimulus applied.

Health risks caused by freshwater cyanobacteria in recreational waters.

Abstract: Toxic cyanobacteria are increasingly being perceived as a potential health hazard, particularly in waters used for recreation. A few countries are developing regulations to protect human health from these toxins, and the World Health Organization (WHO) has published both a guideline value for one cyanotoxin in drinking water and a procedural guideline for recreational waters. This article presents an overview of the currently known cyanotoxins and of documented cases of human illnesses attributed to them. It further discusses exposure pathways and approaches to risk management. In this context, the WHO guideline for recreational waters is presented, and monitoring approaches are outlined.

Plant uptake of radiocaesium: a review of mechanisms, regulation and application.

Abstract: Soil contamination with radiocaesium (Cs) has a long-term radiological impact because it is readily transferred through food chains to human beings. Plant uptake is the major pathway for the migration of radiocaesium from soil to human diet. The plant-related factors that control the uptake of radiocaesium are reviewed. Of these, K supply exerts the greatest influence on Cs uptake from solution. It appears that the uptake of radiocaesium is operated mainly by two transport pathways on plant root cell membranes, namely the K(+) transporter and the K(+) channel pathway. Cationic interactions between K and Cs on isolated K-channels or K transporters are in agreement with studies using intact plants. The K(+) transporter functioning at low external potassium concentration (often <0.3 mM) shows little discrimination against Cs(+), while the K(+) channel is dominant at high external potassium concentration with high discrimination against Cs(+). Caesium has a high mobility within plants. Although radiocaesium is most likely taken up by the K transport systems within the plant, the Cs:K ratio is not uniform within the plant. Difference in internal Cs concentration (when expressed on a dry mass basis) may vary by a factor of 20 between different plant species grown under similar conditions. Phytoremediation may be a possible option to decontaminate radiocaesium-contaminated soils, but its major limitation is that it takes an excessively long time (tens of years) and produces large volumes of waste.

Dynamics of grape berry growth and physiology of ripening.

Abstract: Data from two experiments on development of grape berries is re-examined with emphasis on partitioning of berry weight into non-solutes per berry (largely water) and solutes per berry (largely sugar), using weight times juice °Brix. This approach is based on the thought that, since xylem flow is blocked after veraison, time curves of solutes per berry indicate the activity of phloem transport into the berry during ripening growth. Experiment 1: Measurements of Muscat Gordo Blanco berries from inflorescences with a spread of flowering times showed typical double-sigmoid volume/time curves but with divergent rates and amounts of volume increase. Despite this divergence, °Brix curves after veraison were almost coincident because, in each case, the rate of increase in solutes per berry was proportional to that of berry volume. These results indicate that sugar and water increments after veraison are linked and depend on the same source, namely, phloem sap. Experiment 2: An irrigation experiment on cv. Shiraz also showed divergent berry weight curves between treatments and years but with the difference that all berries shrank after a maximum berry weight was attained at 91 days after flowering (at about 20 °Brix). At this point, the curves of solutes per berry slowed then plateaued, indicating that inflow of phloem sap had become impeded. Prior to shrinkage these berries accumulated primary metabolites (mainly phloem sugar) but, during shrinkage, when berries were apparently isolated from vascular transport, non-anthocyanin glycosides accumulated. These results have implications for the study of berry flavour build-up and berry composition, and also for the understanding of sink competition within the vine, fresh and dried yield, and juice °Brix levels.

Canopy microclimate and berry composition: The effect of bunch exposure on the phenolic composition of Vitis vinifera L cv. Shiraz grape berries

Abstract: Studies on the effect of light exposure on specific phenolic compounds of berries from Shiraz vines grown in a hot climate are reported. Berries that had developed on bunches receiving high levels of ambient light generally had the highest relative levels of quercetin-3-glucoside and a lower proportion of their malvidin anthocyanins as the coumarate derivative, compared to berries that had developed on bunches in shaded canopy conditions. The response of total anthocyanin levels to treatment conditions was variable and depended on the degree of bunch shading and the resultant berry temperature. It appears that a high degree of bunch exposure in hot climates is not conducive to optimal anthocyanin accumulation in berries. The interactive effects of light and temperature on berry phenolic content and concentration are discussed.

Major Racial Differences in Coronary Constrictor Response Between Japanese and Caucasians With Recent Myocardial Infarction

Abstract: Background—Enhanced coronary vasomotion may contribute to acute coronary occlusion during the acute phase of myocardial infarction (AMI). Japanese have a higher incidence of variant angina than Caucasian patients, but racial differences in vasomotor reactivity early after AMI are controversial. Methods and Results—The same team studied 15 Japanese and 19 Caucasian patients within 14 days of AMI by acetylcholine injection into non–infarct-related (NIRA) and infarct-related (IRA) coronary arteries followed by nitroglycerin. Incidence of vasodilation, vasoconstriction, spasm, and basal tone were assessed in proximal, middle, and distal segments after each drug bolus by quantitative angiography. Japanese patients had much lower cholesterol levels than Caucasians (183±59 versus 247±53 mg/dL, P<0.006) but showed a lower incidence of vasodilation (2% versus 9% of coronary segments) and a greater incidence of spasm after acetylcholine (47% versus 15% of arteries, P<0.00001). Incidence of spasm was higher in IRAs ...

Acute coronary findings at autopsy in heart failure patients with sudden death: results from the assessment of treatment with lisinopril and survival (ATLAS) trial.

Abstract: Background—Sudden unexpected death frequently occurs in chronic heart failure. The importance of acute coronary events in triggering sudden death (SD) is unclear. Methods and Results—We evaluated at autopsy the prevalence of acute coronary findings (coronary thrombus, ruptured plaque, or myocardial infarction [MI]) and their relation to SD. Autopsy results in 171 patients in the randomized ATLAS trial were reviewed. The prevalence of acute coronary findings was 33%: in 54% of patients with significant coronary artery disease (CAD) who died suddenly, 32% who died of myocardial failure, but in non-CAD patients, they were present in only 5% and 10% respectively. The percentage of patients classified as dying of MI was 28% in the autopsy group versus 4% in the nonautopsied group (P<0.0001). Of the autopsied group with acute MI, 97% (31 of 32 patients) with SD and 40% (6 of 15 patients) with myocardial failure did not have the MI diagnosed during life. When undiagnosed MI was classified as “sudden unexpected” ...

Breeding for Trace Mineral Density in Rice

Abstract: In 1992 the International Rice Research Institute (IRRI) began to examine the effect of certain soil characteristics on the iron content of rice grains. As part of the Consultative Group for Intern...

Cosmic ray bound for models of extragalactic neutrino production

Abstract: We obtain the maximum diffuse neutrino intensity predicted by hadronic photoproduction models of the type which have been applied to the jets of active galactic nuclei or gamma ray bursts. For this, we compare the proton and gamma ray fluxes associated with hadronic photoproduction in extragalactic neutrino sources with the present experimental upper limit on cosmic ray protons and the extragalactic gamma ray background, employing a transport calculation of energetic protons traversing cosmic photon backgrounds. We take into account the effects of the photon spectral shape in the sources on the photoproduction process, cosmological source evolution, the optical depth for cosmic ray ejection, and discuss the possible effects of magnetic fields in the vicinity of the sources. For photohadronic neutrino sources which are optically thin to the emission of neutrons we find that the cosmic ray flux imposes a stronger bound than the extragalactic gamma ray background in the energy range between 10^5 GeV and 10^11 GeV, as previously noted by Waxman & Bahcall (1999). We also determine the maximum contribution from the jets of active galactic nuclei, using constraints set to their neutron opacity by gamma-ray observations. This present upper limit is consistent with the jets of active galactic nuclei producing the extragalactic gamma ray background hadronically, but we point out future observations in the GeV-to-TeV regime could lower this limit. We also briefly discuss the contribution of gamma ray bursts to ultra-high energy cosmic rays as it can be inferred from possible observations or limits on their correlated neutrino fluxes.

A Proton Synchrotron Blazar Model for Flaring in Markarian~501

Abstract: (abr.) The spectral energy distribution (SED) of blazars typically has a double-humped appearance usually interpreted in terms of synchrotron self-Compton models. In proton blazar models, the SED is instead explained in terms of acceleration of protons and subsequent cascading. We discuss a variation of the Synchrotron Proton Blazar model, first proposed by Mucke & Protheroe (1999), in which the low energy part of the SED is mainly synchrotron radiation by electrons co-accelerated with protons which produce the high energy part of the SED mainly asproton synchrotron radiation. Using a Monte Carlo/numerical technique to simulate the interactions and subsequent cascading of the accelerated protons, we are able to fit the observed SED of Markarian 501 during the April 1997 flare. We find that the emerging cascade spectra initiated by gamma-rays from $\pi^0$ decay and by $e^\pm$ from $\mu^\pm$ decay turn out to be relatively featureless. Synchrotron radiation produced by $\mu^\pm$ from $\pi^\pm$ decay, and even more importantly by protons, and subsequent synchrotron-pair cascading, is able to reproduce well the high energy part of the SED. For this fit we find that synchrotron radiation by protons dominates the TeV emission, pion photoproduction being less important with the consequence that we predict a lower neutrino flux than in other proton blazar models.

Body mass and probability of pregnancy during assisted reproduction treatment: retrospective study.

Abstract: Being underweight or overweight has an adverse effect on reproduction.1,2 Overweight women have a higher incidence of menstrual dysfunction and anovulation, possibly because of altered secretion of pulsatile gonadotropin releasing hormone, sex hormone binding globulin, ovarian and adrenal androgen, and luteinising hormone and also because of altered insulin resistance. The prevalence of obesity in infertile women is high, but there is no conclusive evidence that extremes of weight are associated with a low rate of pregnancy in women receiving assisted reproduction treatment. This study examined whether body mass index (weight (kg)/(height (m)2)) is associated with reduced fecundity (the probability of achieving at least one pregnancy during treatment) in women receiving assisted reproduction treatment.

Spatial differences in acquisition of soil phosphate between two arbuscular mycorrhizal fungi in symbiosis with Medicago truncatula

Abstract: Responses of Medicago truncatula to colonization by two arbuscular mycorrhizal fungi, Scutellospora calospora isolate WUM 12(2) and Glomus caledonium isolate RIS 42, were compared in the light of previous findings that the former fungus can be ineffective as a beneficial microsymbiont with some host plants. The plants were grown individually in two-compartment systems in which a lateral side arm containing soil labelled with 33P was separated from the main soil compartment by a nylon mesh that prevented penetration by roots but not fungal hyphae. Fungal inoculum was applied as a root–soil mixture in a band opposite the side arm. Nonmycorrhizal controls were set up similarly, without inoculum. There were harvests at 28, 35, 42 and 49 d. Both sets of mycorrhizal plants grew better than nonmycorrhizal plants and initially had higher concentrations of P in shoots and roots. Plants grown with S. calospora grew better than plants grown with G. caledonium, and this was associated with somewhat greater fungal colonization in terms of intraradical hyphae and numbers of arbuscules. Scutellospora calospora formed denser hyphae at root surfaces than G. caledonium. By 28 d there were extensive hyphae of both fungi in the side arms, and after 35 d S. calospora produced denser hyphae there than G. caledonium. Nevertheless, there was very little transfer of 33P via S. calospora to the plant at 28 d, and thereafter its transfer increased at a rate only c. 33% of that via G. caledonium. The results showed that plants colonized by S. calospora preferentially obtained P from sites in the main soil chamber relatively close to the roots, compared with plants colonized by G. caledonium. Hence formation of a highly beneficial arbuscular mycorrhizal symbiosis does not necessarily depend on development of hyphae at a distance from the roots or on large-scale translocation of P from distant sites. The results are discussed in relation to previous studies with compartmented systems that have involved the same fungi. Possible causes of the variable effects of S. calospora in symbiosis with different host plants are briefly assessed. Differences in spatial abilities of individual arbuscular mycorrhizal fungi to acquire P might have strong ecological implications for plant growth in soils low in P.

Breeding for Trace Minerals in Wheat

Abstract: In the search for genetic material with high iron and zinc concentration in wheat grain, a significant positive correlation has been found between iron and zinc concentrations, suggesting that these two traits may be combined relatively easily during breeding. In future research, the very high values of iron and zinc in the grain seen in wild types and landraces need to be confirmed in trials in which all the best material is planted in the same location and year. In addition, it is important to determine if these high levels of iron and zinc in the grain can be maintained in high-yielding material.The production of semi-dwarf wheat through the introduction of the rht genes has resulted in substantial yield increases. However, this is associated with a reduction in iron and zinc concentrations in some bread wheat genotypes, but not in durum wheat. The presence of the 1B/1R translocation in the wheat germplasm of the Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT) to increase leaf rust resist...

Factors associated with hospital admissions and repeat emergency department visits for adults with asthma

Abstract: BACKGROUND—A small proportion of patients with asthma account for a disproportionate number of acute health service events. To identify whether factors other than severity and low socioeconomic status were associated with this disproportionate use, a prospective study was undertaken to examine management and psychosocial factors associated with increased risk for admission to hospital with asthma and repeat visits to the emergency department over a 12month period. METHODS—A total of 293 patients with moderate or severe asthma managed at least in part at two teaching hospitals completed surveys of clinical status, acute events, sociodemographic, and psychological variables. RESULTS—Twenty three percent had a single admission to hospital and 16% had two or more hospital admissions. Twenty six percent had one emergency department visit and 32% had two or more visits to the emergency department. In a multiple logistic regression model, adjusted for age, sex, education and income, odds ratios (95% CI) for baseline factors associated with hospital admissions over the next 12 months were: moderate severity compared with severe asthma 0.6 (0.2 to 0.9); no hospital admissions in the past 12 months 0.1 (0.01 to 0.2); not possessing a written asthma action plan 4.0 (1.5 to 10.7); less use of an avoidance coping style 0.4 (0.3 to 0.7); lower preferences for autonomy in asthma management decisions 1.4 (0.96 to 2.0). Adjusted odds ratios (95% CI) for repeat emergency department visits were: moderate asthma severity 0.3 (0.1 to 0.8); current regular use of oral corticosteroids 10.0 (3.1 to 32.4); a hospital admission in the past 12 months 2.9 (1.8 to 4.8); not possessing a written asthma action plan 2.2 (1.1 to 5.6); less dislike of asthma medications 0.7 (0.5to 0.9). CONCLUSIONS—In addition to factors relating to severity, not possessing a written asthma action plan, avoidance coping, and attitudes to self-management were related to acute use of health services in this at risk group. Interventions need to address or take these factors into account to reduce asthma morbidity.

Leak Detection and Calibration Using Transients and Genetic Algorithms

Abstract: Leak detection and calibration of pipe internal roughnesses in a water distribution network are significant issues for water authorities around the world. Computer simulation of water distribution systems to determine the location and size of leaks is emerging as an important tool. A major uncertainty in developing computer models is the condition of the interior of the pipes in the network, especially if they are old. An innovative technique for leak detection and calibration called the inverse transient technique has been recently developed. This paper uses the genetic algorithm (GA) technique in conjunction with the inverse transient method to detect leaks and friction factors in water distribution systems. A continuous variable representation has been developed for the GA coding scheme in this paper. Two new GA operators for crossover and mutation are also introduced. The inverse transient method using the GA technique is effective at finding leakage locations and magnitudes while simultaneously findi...

The antibiotic and anticancer active aurein peptides from the Australian Bell Frogs Litoria aurea and Litoria raniformis the solution structure of aurein 1.2.

Abstract: Seventeen aurein peptides are present in the secretion from the granular dorsal glands of the Green and Golden Bell Frog Litoria aurea, and 16 from the corresponding secretion of the related Southern Bell Frog L. raniformis. Ten of these peptides are common to both species. Thirteen of the aurein peptides show wide-spectrum antibiotic and anticancer activity. These peptides are named in three groups (aureins 1-3) according to their sequences. Amongst the more active peptides are aurein 1.2 (GLFDIIKKIAESF-NH2), aurein 2.2 (GLFDIVKKVVGALGSL-NH2) and aurein 3.1 (GLFDIVKKIAGHIAGSI-NH2). Both L. aurea and L. raniformis have endoproteases that deactivate the major membrane-active aurein peptides by removing residues from both the N- and C-termini of the peptides. The most abundant degradation products have two residues missing from the N-terminal end of the peptide. The solution structure of the basic peptide, aurein 1.2, has been determined by NMR spectroscopy to be an amphipathic alpha-helix with well-defined hydrophilic and hydrophobic regions. Certain of the aurein peptides (e.g. aureins 1.2 and 3.1) show anticancer activity in the NCI test regime, with LC50 values in the 10-5-10-4 M range. The aurein 1 peptides have only 13 amino-acid residues: these are the smallest antibiotic and anticancer active peptides yet reported from an anuran. The longer aurein 4 and 5 peptides, e.g. aurein 4.1 (GLIQTIKEKLKELAGGLVTGIQS-OH) and aurein 5. 1 (GLLDIVTGLLGNLIVDVLKPKTPAS-OH) show neither antibacterial nor anticancer activity.

Virus-Induced Silencing of a Plant Cellulose Synthase Gene

Abstract: Specific cDNA fragments corresponding to putative cellulose synthase genes (CesA) were inserted into potato virus X vectors for functional analysis in Nicotiana benthamiana by using virus-induced gene silencing. Plants infected with one group of cDNAs had much shorter internode lengths, small leaves, and a “dwarf” phenotype. Consistent with a loss of cell wall cellulose, abnormally large and in many cases spherical cells ballooned from the undersurfaces of leaves, particularly in regions adjacent to vascular tissues. Linkage analyses of wall polysaccharides prepared from infected leaves revealed a 25% decrease in cellulose content. Transcript levels for at least one member of the CesA cellulose synthase gene family were lower in infected plants. The decrease in cellulose content in cell walls was offset by an increase in homogalacturonan, in which the degree of esterification of carboxyl groups decreased from ∼50 to ∼33%. The results suggest that feedback loops interconnect the cellular machinery controlling cellulose and pectin biosynthesis. On the basis of the phenotypic features of the infected plants, changes in wall composition, and the reduced abundance of CesA mRNA, we concluded that the cDNA fragments silenced one or more cellulose synthase genes.

A "Mouth-feel Wheel": terminology for communicating the mouth-feel characteristics of red wine

Abstract: A hierarchically structured vocabulary of mouth-feel sensations elicited by red wines has been produced. Represented as a wheel, this structured vocabulary should assist tasters in their interpretation and use of terminology relating to 'in mouth' sensations produced by red wines. These terms and their definitions were generated by consulting the opinions of experienced wine tasters following exposure to an extensive range of commercial red wines. Logical relationships among the derived terms were formulated by analysis of 'sorting data' provided by a combined group of experienced winemakers and wine-tasters.