Showing papers by "Queensland University of Technology published in 1990"

Cell death induced in a murine mastocytoma by 42-47°C heating in vitro: Evidence that the form of death changes from apoptosis to necrosis above a critical heat load

Abstract: SummaryThe pathogenesis of heat-induced cell death is controversial. Categorizing the death occurring after various heat loads as either apoptosis or necrosis might help to elucidate this problem, since it has been shown that these two processes differ in their mode of initiation as well as in their morphological and biochemical features. Log-phase cultures of mastocytoma P-815 × 2·1 were heated at temperatures ranging from 42 to 47°C for 30 min. After 42°C heating a slight increase in apoptosis was observed morphologically. However, after heating at 43, 43.5 and 44°C, there was marked enhancement of apoptosis, and electrophoresis of DNA showed characteristic internucleosomal cleavage. With heating at 45°C both apoptosis and necrosis were enhanced, whereas at 46 and 47°C only necrosis was produced. DNA extracted from the 46 and 47°C cultures showed virtually no degradation, which contrasts with the random DNA breakdown observed in necrosis produced by other types of injury; lysosomal enzymes released duri...

Saccadic oscillations facilitate ocular perfusion from the avian pecten

Abstract: THE evolution of the eye is constrained by two conflicting requirements—good vascular perfusion of the retina, and an optical path through the retina that is unobstructed by blood vessels. Birds are interesting in that they have higher metabolic rates and thicker retinas than mammals, but have no retinal blood vessels. Nutrients and oxygen must thus reach the neurons of the inner retina either from the choroid through 300 μm of metabolically very active retina, or from the pecten, a pleated vascular structure protruding from the head of the optic nerve into the vitreous chamber, and more than a centimetre away from some retinal neurons. Despite the diffusional distance involved, several lines of evidence indicate that the pecten is the primary source of nutrients for the inner retina: the presence of an oxygen gradient from pecten to retina1, the large surface area produced by macroscopic folds2,3 and by microscopic infoldings of the luminal and external surfaces of the capillary endothelium4–6, extrusion of circulating fluorescein7, high content of carbonic anhydrase and alkaline phosphatase8,9, and retinal impairments after pecten ablation1. Another peculiarity of birds, their saccadic oscillations, occur with a large cyclotor-sional component during every saccadic eye movement11. In different species, saccades, which occur at intervals of 0.5–40 s, have up to 13 oscillations with frequencies of 15–30 Hz and amplia-tudes of about 10° (ref. 12). Therefore, as much as 12% of some birds' total viewing time may be subject to the image instability caused by the oscillations13. Using fluorescein angiography, we show here that during every saccade, the pecten acts as an agitator which propels perfusate towards the central retina much more effectively than is observed during intersaccadic intervals.

An in vitro technique for the production de novo of multiple shoots in cotyledon explants of cucumber (Cucumis sativus L.)

Abstract: A technique is described for the production de novo of cucumber (Cucumis sativus L.) shoots in the presence of cytokinin using cotyledon explants. The shoots, which arose from adventitious buds and not from enhanced axillary branching, are confined to a specific region at the base of the cotyledon. Concentrations (4 mgl−1 or less) of the cytokinins 6-benzylaminopurine, kinetin and N6-(2-isopentenyl)adenine, are all effective in producing adventitious buds. It is possible to achieve a yield of 23 shoots per cotyledon by removal of the axillary bud. The yield is increased to 50 shoots per cotyledon by cutting the basal region of the cotyledon into small pieces prior to culturing. These techniques may be useful for transformation studies in cucumber.

Reactions of gallium hydrides with 1,4-di-t-butyl-1,4-diazabutadiene; subvalent and hydrometallation products

Abstract: Reaction of LiGaH4 and gallium metal with 1,4-di-t-butyl-1,4-diazabutadiene (dbdab) in diethyl ether at room temperature yields the monomeric, formally gallium(II) species [Ga(dbdab)2], (1), previously prepared using metal vapours, and GaH3·NMe3 with dbdab in hexane at –80 °C yields the novel hydrogallation product [{H2Ga}2{µ-N(But)CH2}2], (2) which has magnetically distinct geminal hydrides (2JHH 44 Hz) in agreement with the crystal structure ( 2.013A, 1.56A) and IR data (νGa–H 1920, 1870 cm–1).

The effects of impurity elements on the reduction of wustite and magnetite to iron in Co/Co2 and H2/H2O gas mixtures

Abstract: The reduction of dense wustite and magnetite samples in CO/CO2 and H2/H2O gas mixtures has shown that impurity elements in solid solution in the oxides can significantly affect the reaction mechanisms operative during reduction and the conditions for porous iron growth. In general, the presence of P, Mg, Ti, Si, Ca, K, and Na in wustite favors, in order of increasing strength, the formation of the porous iron product morphology. Aluminum, on the other hand, significantly reduces the range of gas conditions over which the porous iron microstructure may be obtained.

Lipid classes and fatty acid composition of the eggs of some Australian fish

Abstract: 1. 1. Wax esters, triglycerides, sterols and their esters and phospholipids were found in the eggs of six species of Australian fish. 2. 2. The high proportion of wax ester in golden perch eggs is interpreted as an adaptation to provide bouyancy rather than an additional energy source. 3. 3. Fatty acids of both the ( n -3) and the ( n -6) series were found in the eggs of all species, but the relative proportions of the two fatty acid series indicated a greater dependence on the ( n -3) than on the ( n -6) series in barramundi and golden perch than in the other species.

The life circumstances of aged people with an intellectual disability

Abstract: This paper reports the results of a survey of people over the age 50 years who have a mild or moderate intellectual disability as their primary disability. The objective of the study was to depict ...

Sediment-water interaction as a control on geochemical evolution of playa lake systems in the Australian arid interior

Abstract: Saline playa lakes represent major geomorphic and hydrologic components of internal drainage basins in the arid to semiarid interior of Australia. These lakes mark the outcrop areas of regional shallow groundwater; thus, they are effective hydro-chemical sinks for elemental concentration and authigenic formation of carbonate, evaporite, and silica/silicate minerals.

Optical design of poly{methyl methacrylate) intraocular lenses

Abstract: The effect of poly(methyl methacrylate) intraocular lens shape on optical performance of pseudophakic eyes was investigated. Image quality criteria included wave aberrations, spot diagrams, longitudinal aberrations, the modulation transfer function, and an optimization procedure. For eyes with corneal asphericities encompassing most of the population, the optimum lens form for on-axis vision is close to plano-convex, with the more curved surface facing the cornea. This applies whether lenses are correctly centered, tilted, or decentered. For small off-axis angles, optimum lens shape varies with the ocular parameters. Good intraocular lens shapes range from the plano-convex to the equi-convex. Plano-convex lenses with the curved surface facing the retina are not recommended.

Behaviour of CAPM Anomalies in Smaller Firms: Australian Evidence

Abstract: This study considers the behaviour of the size, price earnings and book value anomalies in smaller firms. It does so by first separately, and then simultaneously, examining the effect of all three firm variables in the Australian stock market, where large firms are no bigger than the smaller firms in the United States. Of the three effects only the book value and (previously confirmed) small firm main effect, but not the P/E effect, is present for Australian stocks. This result suggests that the P/E effect reported in the U.S. literature may disappear in (very) small U.S. stocks. With regard to possible subsumptions and interactions between the effects, our results indicate, though inconclusively, that the small firm effect is driving the book value main effect.

Comparison of Block Ciphers

Abstract: Several DES replacement block ciphers have been published. In this paper a report will be given on the development of a package for analysis and comparison of block ciphers. Experimental results are presented on applying this package to DES, FEAL-N, and Madryga ciphers.

Investigation of central visual fields in patients with age-related macular changes.

Abstract: The effect of early macular pigmentary and drusen changes on the central visual field was investigated in elderly patients with normal visual acuities. Visual field measurements were taken with the Humphrey Field Analyser using its 24-2 and 10-2 full threshold programs. No significant differences were found between two patients groups, one with and one without the macular changes. We conclude that fine pigmentary changes and hard drusen do not cause changes in visual functioning and can be accepted as normal age-related changes.

Speech encryption in the transform domain

Abstract: A comparison has been made of the use of five discrete orthogonal transforms in speech encryption systems. Four objective measures were used to grade the encryption systems with respect to residual intelligibility and recovered voice quality. A figure of merit based on all the objective measures was formed which gave good correlation to the subjective results of residual intelligibility and recovered speech quality.

Symptoms associated with VDT use

Abstract: only Symptoms associated with the eyes were recorded by a group of 92 video display terminal (VDT) users over five years. A diary was maintained for the symptoms and other task related factors such as the type of work performed. Diary entries were recorded approximately every two hours. Symptoms were classified as either ocular (a range of discomfort symptoms), visual (blur or double vision) and systemic (headache or postural symptoms).Tired eyes and headaches were the most frequently reported symptoms. Comparing the symptoms reported during VDT work sessions and the clerical (non-VDT) work sessions, there was a small but consistent trend towards more frequent symptoms during VDT sessions. Almost all types of symptoms showed a significant increase in frequency over the day (time of day effect).

Vision screening and symptoms among VDT users

Abstract: We conducted eye examinations on 79 subjects who used visual display terminals (VDTs) for a significant portion of their normal working day. The examination included the detection of ocular pathology, near and intermediate visual acuity, accommodative facility, fusional vergences, near point of convergence, fixation disparity, near horizontal heterophoria and colour vision. Each subject maintained a diary over five working days in which they recorded the frequency and intensity of symptoms experienced. Symptoms were classed as either ocular (discomfort) or visual (blur) symptoms. Multiple regression analysis techniques were used to investigate the relationship between symptoms and eye examination results and demographic characteristics of subject gender, age and experience with VDTs. None of the eye examination findings were significantly associated with symptoms and of the demographic variables, only VDT experience was significantly associated with symptom rates. Statistical associations were limited in a number of measures by the relatively small population of VDT users sampled.

Vision screening and symptoms among VDT users

Abstract: We conducted eye examinations on 79 subjects who used visual display terminals (VDTs) for a significant portion of their normal working day. The examination included the detection of ocular pathology, near and intermediate visual acuity, accommodative facility, fusional vergences, near point of convergence, fixation disparity, near horizontal heterophoria and colour vision. Each subject maintained a diary over five working days in which they recorded the frequency and intensity of symptoms experienced. Symptoms were classed as either ocular (discomfort) or visual (blur) symptoms. Multiple regression analysis techniques were used to investigate the relationship between symptoms and eye examination results and demographic characteristics of subject gender, age and experience with VDTs. None of the eye examination findings were significantly associated with symptoms and of the demographic variables, only VDT experience was significantly associated with symptom rates. Statistical associations were limited in a number of measures by the relatively small population of VDT users sampled.

Age-related maculopathy. I: A review of its morphology and effects on visual function

Abstract: Age-related maculopathy (ARM) is a leading cause of permanent vision loss in elderly people. ARM therefore constitutes an important public health problem which will increase in magnitude as the number of aged people in the general population becomes greater. The consequences of this condition are exacerbated by the fact that treatment, especially of the atrophic form of the disease, is ineffective. While laser photocoagulation may be helpful in the exudative form of ARM, there is often an inexorable progression towards severe vision loss in these patients. Therefore considerable attention needs to be paid to the aetiology of ARM, the potential for its prevention or delayed onset and its recognition through functional disturbances. This is the first of three papers dealing with ARM and its effects on visual function. We review its morphology and the visual disturbances that may ensue. The second and third papers will discuss the nature and detection of the central visual field loss due to ARM.

Two dimensional modelling of three core cable transient temperature rise

Abstract: A study of the transient temperature rise of a three-core cable is described. A literature search was unable to uncover any reference on this topic since a paper by F.O. Wollaston (Trans. AIEE, vol.68, pt.11, p.1284-97, 1949). Results from a computer program that models the two-dimensional heat flow are compared with those obtained using the normally applied one-dimensional model. The modeling technique is an alternative to the finite-difference and finite-element methods. It develops the concept of a thermal resistance/capacitance analog, as can be done using the finite-difference method, but does so more directly without the need to use the partial-differential equation. In addition, it provides the flexibility of the finite-element method when modeling a complex geometry and material combination, such as that found in a three-core cable, without the complexity of its mathematics. >

Analysing ordered categorical data from two independent samples

Abstract: BrMedJ 1990;301:971-3 Medical journals now require point estimates and confidence intervals in addition to p values.1 Statistics with Confidence provides advice on calculating confi? dence intervals for many types of data2 but not for ordered categorical data. Nevertheless, as much as 20% of reported medical research produces data in ordered categories.3 The Apgar score, the Glasgow coma scale, quality of life and severity of illness indexes, and several methods for staging tumours and grading the severity of disorders such as congestive heart failure are some of the many methods used in clinical medicine which produce data in ordered cate? gories.4 Moreover, current interest in quality assurance in hospitals is likely to result in an increase in the use of methods which produce data in ordered categories.5 Finally, it is often useful to place continuous data in ordered categories as the resulting tabulations aid in their interpretation. In this paper we describe estimators which are appropriate for comparing data in which there are two independent exposure groups and an ordered categorical outcome. Because they offer familiar, prac? tically useful interpretations they should prove suitable to communicate information to clinicians and other health workers. These estimators are related to the rank sum test, which can be used to obtain significance levels. In addition, bootstrapping,6 7 a computer based method, can be used to calculate confidence intervals.

A study of vertical velocity distributions in the planetary boundary layer

Abstract: Until recently, pollution dispersion models have made predictions on the basis that the pollutant concentration is Gaussian. Such is not the case for convective conditions where the observed vertical velocity distribution is skewed towards the updraught portion of the distribution. One recent dispersion model assumes that the observed distribution can be synthesized by superimposing two Gaussians of appropriate means, variances and amplitudes. In the current paper, two techniques for deriving the constituent distributions are investigated. The first technique is based on conditionally sampling the vertical velocity time series and partitioning the vertical velocity samples into two sets — one set recorded when the sensor was experiencing an updraught and the other when the sensor was experiencing a downdraught. The second method consists of fitting two Gaussian distributions to the observed data and adjusting these using an iterative procedure until a specified tolerance is achieved. Both techniques give similar results which compare favourably with results obtained by other researchers. Assumptions, as well as advantages and disadvantages of each technique are also discussed.

Speech encryption using discrete orthogonal transforms

Abstract: The performances of five discrete orthogonal transforms in speech encryption systems are compared. The transforms considered are the discrete Fourier transform, discrete cosine transform, Walsh-Hadamard transform, Karhunen-Loeve transform, and discrete prolate spheroidal transform. Four objective measures are used to grade the encryption systems with respect to residual intelligibility and recovered voice quality. A figure of merit based on all the four objective measures is formed. It gives good correlation to the subjective results of residual intelligibility and recovered speech quality. >

Research into the environment of science laboratory classes in australian schools

Abstract: Existing instruments for assessing student or teacher perceptions of characteristics of actual or preferred classroom psychosocial environment are unsuitable for one of the most important settings in science teaching, namely, the science laboratory class. Consequently, the Science Laboratory Environment Inventory (SLEI), was designed to assess student or teacher perceptions of seven scales:Teacher Supportiveness, Student Cohesiveness, Open-Endedness, Integration, Organization, Rule Clarity andMaterial Environment. An important feature of the design of the study was that the new instrument was field tested simultaneously in six countries: Australia, USA, Canada, England, Nigeria and Israel. This paper is based on a sample of 4643 students in 225 individual laboratory classes, together with the teachers of most of these classes. Preliminary analyses were used to shed light on various important research questions including the differences between Actual and Preferred environments, gender differences in perceptions of Actual and Preferred environment, the relationship between the science laboratory environment and attitude towards science laboratory work, differences between school and university laboratory classes, differences between teachers’ and students’ perceptions of the same laboratory classes, and differences between laboratory classes in different science subjects (Physics, Chemistry, Biology).

A survey of symptoms and eye safety practices among welders

Abstract: Welding is a task which is potentially hazardous to the eyes. In this study we have administered a questionnaire to 128 welders to investigate ocular symptoms and eye safety practices when welding. The welders demonstrated high levels of discomfort symptoms which were correlated with the length of unprotected exposure to nearby welding, the number of welding flashes received and the length of time spent welding. Dust and fumes in the workplace were also a frequent cause of ocular discomfort. Foreign body injuries were common among the welders, many of whom also reported after-images persisting following welding.