Analysis of soil wetting and solute transport in subsurface trickle irrigation

The increased use of trickle or drip irrigation is seen as one way of helping to improve the sustainability of irrigation systems around the world. However, soil water and solute transport properties and soil profile characteristics are often not adequately incorporated in the design and management of trickle systems. In this paper, we describe results of a simulation study designed to highlight the impacts of soil properties on water and solute transport from buried trickle emitters. The analysis addresses the influence of soil hydraulic properties, soil layering, trickle discharge rate, irrigation frequency, and timing of nutrient application on wetting patterns and solute distribution. We show that (1) trickle irrigation can improve plant water availability in medium and low permeability fine-textured soils, providing that design and management are adapted to account for their soil hydraulic properties, (2) in highly permeable coarse-textured soils, water and nutrients move quickly downwards from the emitter, making it difficult to wet the near surface zone if emitters are buried too deep, and (3) changing the fertigation strategy for highly permeable coarse-textured soils to apply nutrients at the beginning of an irrigation cycle can maintain larger amounts of nutrient near to and above the emitter, thereby making them less susceptible to leaching losses. The results demonstrate the need to account for differences in soil hydraulic properties and solute transport when designing irrigation and fertigation management strategies. Failure to do this will result in inefficient systems and lost opportunities for reducing the negative environmental impacts of irrigation.

An analysis of valve re-replacement after aortic valve replacement with biologic devices

Biologic valve re-replacement was examined in a series of 1343 patients who underwent aortic valve replacement at The Prince Charles Hospital, Brisbane, with a cryopreserved or 4 degrees C stored allograft valve or a xenograft valve, A parametric model approach was used to simultaneously model the competing risks of death without re-replacement and re-replacement before death, One hundred eleven patients underwent a first re-replacement for a variety of reasons (69 patients with xenograft valves, 28 patients with 4 degrees C stored allograft valves, and 14 patients with cryopreserved allograft valves), By multivariable analysis younger age at operation was associated with xenograft, 4 degrees C stored allograft, and cryopreserved allograft valve re-replacement, However, this effect was examined in the context of longer survival of younger patients, which increases their exposure to the risk of re-replacement as compared with that in older patients whose decreased survival reduced their probability of requiring valve re-replacement, In patients older than 60 years at the time of aortic valve replacement, the probability of re-replacement (for any reason) before death was similar for xenografts and cryopreserved allograft valves but higher for 4 degrees C stored valves, However, in patients younger than 60 years, the probability of re-replacement at any time during the remainder of the life of the patient was lower with the cryopreserved allograft valve compared with the xenograft valve and 4 degrees C stored allografts.

Notes on market failure and the Paretian (Kaldor-Hicks) relevance and irrelevance of unfavourable externalities

The following are notes that have been distributed by me over the last few years to students in Environmental Economics at The University of Queensland. They give particular attention to whether externalities are Pareto or Kaldor-Hicks relevant from a policy point of view. Externalities are Kaldor-Hicks or Pareto irrelevant if no change is possible for which gainers could compensate losers. Both absolute and marginal externalities may be Kaldor-Hicks relevant. Infra-marginal negative externalities are often, but not always, Kaldor-Hicks irrelevant. There are at least two cases where such externalities can be relevant. First, the absolute impact of the negative externality may be so great that the source of the externality should be eliminated. Secondly, if the externality arises from production, its nature may depend on the type of production technique adopted. Although for the technique adopted, an infra-marginal negative externality occurs. That is Paretian irrelevant given that choice of this technique is the only available possibility, alternative techniques may actually be available in practice. Some of these may generate even smaller total external effects and be socially preferable. Both cases are outlined and illustrated in these notes. The analysis reveals the dangers of relying on marginalism for deciding on environmental policy. Total (external) effects are often of great social and economic importance and appropriate social choices cannot be made on the basis of marginalism alone.

The Environment and the Selection of Aquaculture Species and Systems: An Economic Analysis

Environmental conditions play a significant role in the economic success of aquaculture. This article classifies environmental factors in a way that facilitates economic analysis of their implications for the selection of aquaculture species and systems. The implication of on-farm as on-site environmental conditions for this selection are considered first using profit-possibility frontiers and taking into account the biological law of environmental tolerance. However, in selecting, recommending and developing aquaculture species and systems, it is often unrealistic to assume the degree of managerial efficiency implied by the profit-possibility function. It is appropriate to take account of the degree of managerial inefficiency that actually exists, not all of which may be capable of being eliminated. Furthermore, experimental R&D should be geared to on-farm conditions, and the variability of these conditions needs to be taken into account. Particularly in shared water bodies, environmental spillovers between aquaculturalists can be important and as shown theoretically, can influence the socially optimal selection of aquaculture species and systems. Similarly, aquaculture can have environmental consequences for the rest of the community. The social economic implications of this for the selection of aquaculture species and systems are analyzed. Some paradoxical results are obtained. For example, if the quality of social governance of aquaculture is poor, aquaculture species and systems that cause a slow rate of environmental deterioration may be socially less satisfactory than those that cause a rapid rate of such deterioration. Socially optimal choice of aquaculture species and systems depends not only on their biophysical characteristics and market conditions but also on the prevailing state of governance of aquaculture. Failure to consider the last aspect can result in the introduction of new aquaculture species (and systems) doing more social harm than good.

Analysis of the gate capacitance measurement technique and its application for the evaluation of hot-carrier degradation in submicrometer MOSFETs

The use of gate-to-drain capacitance (C-gd) measurement as a tool to characterize hot-carrier-induced charge centers in submicron n- and p-MOSFET's has been reviewed and demonstrated. By analyzing the change in C-gd measured at room and cryogenic temperature before and after high gate-to-drain transverse field (high field) and maximum substrate current (I-bmax) stress, it is concluded that the degradation was found to be mostly due to trapping of majority carriers and generation of interface states. These interface states were found to be acceptor states at top half of band gap for n-MOSFETs and donor states at bottom half of band gap for p-MOSFETs. In general, hot electrons are more likely to be trapped in gate oxide as compared to hot holes while the presence of hot holes generates more interface states. Also, we have demonstrated a new method for extracting the spatial distribution of oxide trapped charge, Q(ot), through gate-to-substrate capacitance (C-gb) measurement. This method is simple to implement and does not require additional information from simulation or detailed knowledge of the device's structure. (C) 2001 Elsevier Science Ltd. All rights reserved.

Quantitative analysis of the speed and accuracy of tongue movements in dysarthria subsequent to traumatic brain injury using electromagnetic articulography

It has been recognised that in order to study the displacement, timing and co-ordination of articulatory components (i.e., tongue. lips, jaw) in speech production it is desirable to obtain high-resolution movement data on multiple structures inside and outside the vocal tract. Until recently, with the exception of X-ray techniques such as cineradiography, the study 0. speech movements has been hindered by the inaccessibility of the oral cavity during speech. X-ray techniques are generally not used because of unacceptable radiation exposure. The aim of the present study was to demonstrate the use of a new physiological device, the electromagnetic articulograph, for assessing articulatory dysfunction subsequent to traumatic brain injury. The components of the device together with the measuring principle are described and data collected from a single case presented. A 19 year-old male who exhibited dysarthria subsequent to a traumatic brain injury was fitted wit 2 the electromagnetic articulograph (Carstens AG-100) and a kinematic analysis of his tongue movements during production of the lingual consonants it, s, k/ within single syllable words was performed. Examination of kinematic parameters including movemmt trajectories, velocity, and acceleration revealed differences in the speed and accuracy of his tongue movements compared to those produced by a non-neurologically impaired adult male. It was concluded that the articulograph is a useful device for diagnosing speed and accuracy disorders in tongue movements during speech and that the device has potential for incorporation into physiologically based rehabilitation programs as a real-time biofeedback instrument.

Phenotypic and genotypic analysis of Helicoverpa armigera nucleopolyhedrovirus serially passaged in cell culture

Rapid accumulation of few polyhedra (FP) mutants was detected during serial passaging of Helicoverpa armigera nucleopolyhedrovirus (HaSNPV) in cell culture. 100% FP infected cells were observed by passage 6. The specific yield decreased from 178 polyhedra per cell at passage 2 to two polyhedra per cell at passage 6. The polyhedra at passage 6 were not biologically active, with a 28-fold reduction in potency compared to passage 3. Electron microscopy studies revealed that very few polyhedra were produced in an FP infected cell (< 10 polyhedra per section) and in most cases these polyhedra contained no virions. A specific failure in the intranuclear nucleocapsid envelopment process in the FP infected cells, leading to the accumulation of naked nucleocapsids, was observed. Genomic restriction endonuclease digestion profiles of budded virus DNA from all passages did not indicate any large DNA insertions or deletions that are often associated with such FP phenotypes for the extensively studied Autographa californica nucleopolyhedrovirus and Gaileria mellonella nucleopolyhedrovirus. Within an HaSNPV 25K FP gene homologue, a single base-pair insertion (an adenine residue) within a region of repetitive sequences (seven adenine residues) was identified in one plaque-purified HaSNPV FP mutant. Furthermore, the sequences obtained from individual clones of the 25KFP gene PCR products of a late passage revealed point mutations or single base-pair insertions occurring throughout the gene. The mechanism of FP mutation in HaSNPV is likely similar to that seen for Lymantria dispar nucleopolyhedrovirus, involving point mutations or small insertions/deletions of the 25K FP gene.

An EM-based Semi-Parametric Mixture Model Approach to the Regression Analysis of Competing-Risks Data

We consider a mixture model approach to the regression analysis of competing-risks data. Attention is focused on inference concerning the effects of factors on both the probability of occurrence and the hazard rate conditional on each of the failure types. These two quantities are specified in the mixture model using the logistic model and the proportional hazards model, respectively. We propose a semi-parametric mixture method to estimate the logistic and regression coefficients jointly, whereby the component-baseline hazard functions are completely unspecified. Estimation is based on maximum likelihood on the basis of the full likelihood, implemented via an expectation-conditional maximization (ECM) algorithm. Simulation studies are performed to compare the performance of the proposed semi-parametric method with a fully parametric mixture approach. The results show that when the component-baseline hazard is monotonic increasing, the semi-parametric and fully parametric mixture approaches are comparable for mildly and moderately censored samples. When the component-baseline hazard is not monotonic increasing, the semi-parametric method consistently provides less biased estimates than a fully parametric approach and is comparable in efficiency in the estimation of the parameters for all levels of censoring. The methods are illustrated using a real data set of prostate cancer patients treated with different dosages of the drug diethylstilbestrol. Copyright (C) 2003 John Wiley Sons, Ltd.

Etiology of ovarian failure in blepharophimosis ptosis epicanthus inversus syndrome: FOXL2 is a conserved, early-acting gene in vertebrate ovarian development

Blepharophimosis ptosis epicanthus inversus syndrome (BPES) is a human disorder caused by mutations in the forkhead transcription factor gene FOXL2 and is characterized by facial dysmorphology combined in some cases with ovarian failure. To better understand the role of FOXL2 in the etiology of ovarian failure in BPES, we examined its expression in embryonic ovaries of mice, chickens, and red-eared slider turtles, representatives of three phylogenetically distant vertebrate groups that have different mechanisms of sex determination. Expression of Foxl2 was detected in early ovaries of all three species around the time of sex determination and was associated with both somatic and germ cell populations in mice. Expression was sexually dimorphic in all cases. Sequence analysis of turtle and chicken FoxL2 orthologues indicated an unusually high degree of structural conservation during evolution. FoxL2 was found to be autosomal in chickens, and therefore unlikely to represent the dominant ovarian-determining gene that has been postulated to exist as a possible explanation for female heterogamety in birds. Our observations suggest that BPES may result from early abnormalities in regulating the development of the fetal ovary, rather than premature degeneration of the postnatal or adult ovary. Further, our results suggest that FOXL2 is a highly conserved early regulator of vertebrate ovarian development.

Biaxial failure model for fiber reinforced concrete

Steel fiber reinforced concrete (SFRC) is widely applied in the construction industry. Numerical elastoplastic analysis of the macroscopic behavior is complex. This typically involves a piecewise linear failure curve including corner singularities. This paper presents a single smooth biaxial failure curve for SFRC based on a semianalytical approximation. Convexity of the proposed model is guaranteed so that numerical problems are avoided. The model has sufficient flexibility to closely match experimental results. The failure curve is also suitable for modeling plain concrete under biaxial loading. Since this model is capable of simulating the failure states in all stress regimes with a single envelope, the elastoplastic formulation is very concise and simple. The finite element implementation is developed to demonstrate the conciseness and the effectiveness of the model. The computed results display good agreement with published experimental data.

In situ characterization of stickiness of sugar-rich foods using a linear actuator driven stickiness testing device

A stickiness testing device based on the probe tack test has been designed and tested. It was used to perform in situ characterization of drying hemispherical drops with an initial radius 3.5 mm. Tests were carried out in two drying temperatures, 63 and 95 degreesC. Moisture and temperature histories of the drying drops of fructose, honey, sucrose, maltodextrin and sucrose-maltodextrin mixtures were determined. The rates of moisture evaporation of the fructose solution was the fastest while those of the maltodextrin solution was the lowest. A profile reversal was observed when the temperature profiles of these materials were compared. Different modes of failure were observed during the stickiness tests. Pure fructose and honey solutions remained completely sticky and failed cohesively until the end of drying. Pure sucrose solution remained sticky and failed cohesively until complete crystallization occurred. The surface of the maltodextrin drops formed a skin shortly after the start of drying. It exhibited adhesive failure and reached a state of non-adhesion. Addition of maltodextrin significantly altered the stickiness of sucrose solution. (C) 2002 Elsevier Science Ltd. All rights reserved.

Bubble load measurement in the pulp zone of industrial flotation machines - a new device for determining the froth recovery of attached particles

A new device has been developed to directly measure the bubble loading of particle-bubble aggregates in industrial flotation machines, both mechanical flotation cells as well as flotation column cells. The bubble loading of aggregates allows for in-depth analysis of the operating performance of a flotation machine in terms of both pulp/collection zone and froth zone performance. This paper presents the methodology along with an example showing the excellent reproducibility of the device and an analysis of different operating conditions of the device itself. (C) 2004 Elsevier B.V All rights reserved.

Cost of an emerging epidemic: an economic analysis of atrial fibrillation in the UK

Objective: To evaluate the cost of atrial fibrillation (AF) to health and social services in the UK in 1995 and, based on epidemiological trends, to project this estimate to 2000. Design, setting, and main outcome measures: Contemporary estimates of health care activity related to AF were applied to the whole population of the UK on an age and sex specific basis for the year 1995. The activities considered ( and costs calculated) were hospital admissions, outpatient consultations, general practice consultations, and drug treatment ( including the cost of monitoring anticoagulant treatment). By adjusting for the progressive aging of the British population and related increases in hospital admissions, the cost of AF was also projected to the year 2000. Results: There were 534 000 people with AF in the UK during 1995. The direct'' cost of health care for these patients was pound 244 million (similar toE350 million) or 0.62% of total National Health Service ( NHS) expenditure. Hospitalisations and drug prescriptions accounted for 50% and 20% of this expenditure, respectively. Long term nursing home care after hospital admission cost an additional pound46.4 million (similar toE66 million). The direct cost of AF rose to pound459 million (similar toE655 million) in 2000, equivalent to 0.97% of total NHS expenditure based on 1995 figures. Nursing home costs rose to pound111 million (similar toE160 million). Conclusions: AF is an extremely costly public health problem.

Minimal instrumentation may compromise failure diagnosis with an ecological interface

Interfaces designed according to ecological interface design (EID) display higher-order relations and properties of a work domain so that adaptive operator problem solving can be better supported under unanticipated system conditions. Previous empirical studies of EID have assumed that the raw data required to derive and communicate higher-order information would be available and reliable. The present research examines the relative advantages of an EID interface over a conventional piping-and-instrumentation diagram (PID) when instrumentation is maximally or only minimally adequate. Results show an interaction between interface and the adequacy of the instrumentation. Failure diagnosis performance with the EID interface with maximally adequate instrumentation is best overall. Performance with the EID interface drops more drastically from maximally to minimally adequate instrumentation than does performance with the PID interface, to the point where the EID interface with minimally adequate instrumentation supports nonsignificantly worse performance than does the equivalent PID interface. Actual or potential applications of this research include design of instrumentation and displays for complex industrial processes.

Coherent analysis of quantum optical sideband modes

We demonstrate a device that allows for the coherent analysis of a pair of optical frequency sidebands in an arbitrary basis. We show that our device is quantum noise limited, and hence applications for this scheme may be found in discrete and continuous variable optical quantum information experiments. (c) 2005 Optical Society of America.