Showing papers by "Queensland University of Technology published in 1992"
01 Apr 1992
TL;DR: The concept of instantaneous frequency (IF), its definitions, and the correspondence between the various mathematical models formulated for representation of IF are discussed in this paper, and the extent to which the IF corresponds to the intuitive expectation of reality is also considered.
Abstract: The concept of instantaneous frequency (IF), its definitions, and the correspondence between the various mathematical models formulated for representation of IF are discussed. The extent to which the IF corresponds to the intuitive expectation of reality is also considered. A historical review of the successive attempts to define the IF is presented. The relationships between the IF and the group-delay, analytic signal, and bandwidth-time (BT) product are explored, as well as the relationship with time-frequency distributions. The notions of monocomponent and multicomponent signals and instantaneous bandwidth are discussed. It is shown that these notions are well described in the context of the theory presented. >
1,952 citations
01 Apr 1992
TL;DR: The concept of instantaneous frequency (IF) is extended to discrete-time signals and methods based on a modeling of the signal phase as a polynomial have been introduced.
Abstract: For pt.I see ibid., vol.80, no.4, p.520-38 (1992). The concept of instantaneous frequency (IF) is extended to discrete-time signals. The specific problem explored is that of estimating the IF of frequency-modulated (FM) discrete-time signals embedded in Gaussian noise. Well-established methods for estimating the IF include differentiation of the phase and smoothing thereof, adaptive frequency estimation techniques such as the phase locked loop (PLL), and extraction of the peak from time-varying spectral representations. More recently, methods based on a modeling of the signal phase as a polynomial have been introduced. These methods are reviewed, and their performance compared on both simulated and real data. Guidelines are given as to which estimation method should be used for a given signal class and signal-to-noise ratio (SNR). >
793 citations
TL;DR: Absence of a circadian rhythm in these data does not exclude the possibility that initiation of apoptosis in susceptible spermatogonial clones is synchronous, and that affected clones undergo lag periods of differing duration before expressing morphological apoptosis.
Abstract: In this study we examined the possibility that regular or circadian fluctuations occur in the frequency of spontaneous spermatogonial apoptosis. Apoptosis of A2, A3 and A4 type spermatogonia occurring spontaneously in the normal rat testis was studied by light and electron microscopy. Normal and apoptotic A3 spermatogonia were quantified in 36 animals killed at two-hourly intervals over a 24 h period. Three sequential phases of spermatogonial apoptosis were defined and quantified separately: (i) an early phase in which cells showed margination of nuclear chromatin, (ii) an intermediate phase in which phagocytosed apoptotic bodies were partly degraded and (iii) a late phase in which only debris of degraded apoptotic bodies was evident. Groups of spermatogonia linked by intercellular bridges underwent apoptosis synchronously. Normal and apoptotic A3 spermatogonia occurred at a mean frequency of 33.4 and 9.6 per 10 seminiferous tubule profiles respectively; there was a large variation in these frequencies between animals, but no peaks or circadian periodicity were detected. Progressive degradation of apoptotic bodies was evident, the average ratios of intermediate and late bodies to early bodies being 1.5 and 3.5, respectively. Absence of a circadian rhythm in these data does not exclude the possibility that initiation of apoptosis in susceptible spermatogonial clones is synchronous, and that affected clones undergo lag periods of differing duration before expressing morphological apoptosis.
263 citations
TL;DR: In this article, a study focused on the construct of image to identify the ways in which two student teachers think about themselves as teachers and how this relates to their teaching practice, and the findings are used to suggest some implications for teacher educators.
168 citations
TL;DR: The technique was found to produce quantitative agreement with a clinical diagnosis of lymphoedema and with the currently‐used measure (limb volume calculated from circumferential measurements) of limb size.
Abstract: The value of multiple frequency bioelectric impedence analysis (MFBIA) in the monitoring and management of post-mastectomy lymphoedema of the arm was evaluated in 15 patients and controls. The technique was found to produce quantitative agreement with a clinical diagnosis of lymphoedema and with the currently-used measure (limb volume calculated from circumferential measurements) of limb size. The significance of this finding lies in MFBIA being diagnostically informative: it indicates when an observed change in limb volume is directly, albeit theoretically, attributable to accumulation of extracellular fluid. MFBIA potentially offers the means for earlier definitive diagnosis and more-accurate monitoring of extracellular fluid changes during and after treatment.
132 citations
TL;DR: In the absence of significant differences in MI and LI between the ‘normal’ tissue groups, this finding raises the possibility that reduced epithelial cell apoptosis might be causally associated with the development of fibrocystic change and with an increased risk of development of carcinoma.
Abstract: The aims of this study in 227 premenopausal women were (a) to determine the mitotic index (MI), the thymidine labelling index (LI), and the apoptotic index (AI) within the epithelial cells of histologically ‘normal’ human breast biopsy material removed away from the site of either a fibroadenoma or a carcinoma; and (b) to relate differences in the kinetic indices of the ‘normal’ epithelium to the pathology in the same breast diagnosed as fibroadenoma alone (125 patients), fibroadenoma with accompanying mild fibrocystic change (79 patients), or carcinoma (23 patients). Ratios of the average indices (AI/MI, AI/LI, MI/LI) were also calculated to minimize uncertainties related to the total cell population counted, the denominator in the LI, MI, and AI All indices and ratios of indices were corrected for age, averaged over the cycle, and expressed as log-transformed values for analysis. Significant (P<0.001) reductions in AI and in apoptosis relative to mitosis (reduced AI/MI) were found in ‘normal’ epithelium from breasts having fibrocystic change (AI = 0.17 ± 0.02; AI/MI = 1.01 ± 0.18) and carcinoma (AI = 0.19 ± 0.04; AI/MI=0.8 ± 0.29), compared with breast with fibroadenoma alone (AI = 0.27 ± 0.03; AI/MI = 1.29 ± 0.39). In the absence of significant differences in MI and LI between the ‘normal’ tissue groups, this finding raises the possibility that reduced epithelial cell apoptosis might be causally associated with the development of fibrocystic change and with an increased risk of development of carcinoma. Reduced apoptosis may lead to a shift in tissue kinetics towards expansion of cell numbers, and also to the preservation of genetically aberrant cells, favouring neoplastic development. The indices, however, are complex and must be interpreted with caution.
131 citations
TL;DR: Constriction of the binocular visual field to 40° or less significantly increased time taken to complete the course, reduced the ability to detect and correctly identify road signs, avoid obstacles and lo manoeuvre through limited spaces.
128 citations
TL;DR: The theory of BIA is reviewed, recent progress in the development and validation of swept or multiple frequency BIA used to determine both extracellular water and total body water is discussed in detail.
Abstract: The need for a portable, inexpensive, accurate and safe method for measuring body composition is well established. Bioelectrical impedance analysis (BIA) has the potential to partially meet this need by estimating the water component of body composition. There are still a number of unresolved questions and limitations to the applications of BIA, however. This paper briefly reviews the theory of BIA, its application and its limitations. Recent progress in the development and validation of swept or multiple frequency BIA used to determine both extracellular water and total body water is discussed in detail.
121 citations
TL;DR: In this paper, the power of the eye lens is predicted with a modeling approach to determine how the form of the refractive-index gradient within the lens can change to maintain a constant power in spite of age-related curvature increase.
Abstract: A hypothesis is presented that may explain why the aging eye does not become myopic with age. The power of the eye lens is predicted with a modeling approach to determine how the form of the refractive-index gradient within the lens can change to maintain a constant power in spite of age-related curvature increase. Methods used include published age-dependent data on the optical parameters of the eye, a mathematical model of the lens based on elliptical isoindicial contours, and a refractive-index profile that can be expressed as a power series in the distance from the lens center. The kinds of change in profile required to prevent the eye from becoming myopic as its lens grows are shown.
121 citations
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01 Jan 1992TL;DR: Framing culture brings together cultural studies and policy studies in a lively and innovative way as discussed by the authors and suggests avenues for cultural activism that have been neglected in cultural theory and practice, and it will provoke debates which are long overdue.
Abstract: How is contemporary culture 'framed' - understood, promoted, dissected and defended - in the new approaches being employed in university education today? How do these approaches compare with those seen in the public policy process? What are the implications of these differences for future directions in theory, education, activism and policy?
Framing Culture looks at cultural and media studies, which are rapidly growing fields through which students are introduced to contemporary cultural industries such as television, film and video. It compares these approaches with those used to frame public policy and finds a striking lack of correspondence between them.
Issues such as Australian content on commercial television and in advertising, new technologies and new media, and violence in the media all highlight the gap between contemporary cultural theories and the way culture and communications are debated in public policy. The reasons for this gap must be investigated before closer relations can be established.
Framing Culture brings together cultural studies and policy studies in a lively and innovative way. It suggests avenues for cultural activism that have been neglected in cultural theory and practice, and it will provoke debates which are long overdue.
110 citations
TL;DR: An overview of related research areas is given, notably Distributed Artificial Intelligence (DAI) and Distributed Databases (DDBs), and a generic architecture is presented which views an ICIS as a community of communicating and cooperating intelligent information agents.
Abstract: There is a growing belief that the next generation of information processing systems will be based on the paradigm of Intelligent and Cooperative Information Systems (ICISs). Such systems will involve information agents — distributed over the nodes of a common communication network — which work in a synergistic manner by exchanging information and expertise, coordinating their activities and negotiating how to solve parts of a common information-intensive problem. Along with motivating the importance of such systems the paper gives an overview of related research areas, notably Distributed Artificial Intelligence (DAI) and Distributed Databases (DDBs), and presents a generic architecture which views an ICIS as a community of communicating and cooperating intelligent information agents.
TL;DR: In this paper, the visible absorption spectra of the 5′- and 2′-substituted diynes differ markedly, the former compounds exhibiting split absorption bands and red shifts indicative of extensive chromophore interaction.
TL;DR: The PEPSCAN epitope mapping suggested that all the MAbs react with a region of the dengue 2 virus core protein (9RNTPFNMLKRE19) which is adjacent to a putative nuclear localization sequence (6KKAR9) and spans a possible second site for the initiation of synthesis of coreprotein (12PFN decreases MLKR18).
Abstract: Anti-dengue 2 virus core protein monoclonal antibodies (MAbs) reacted with antigens in the cytoplasm and in, or on, the nucleus of dengue 2 and dengue 4, but not dengue 1, dengue 3, Kunjin or Murray Valley encephalitis virus-infected cells. These MAbs also reacted with the core protein from dengue 1, 2 and 4 virions in Western blots. The antigens detected by these MAbs could not be detected in uninfected or heat-shocked cells, but were first detected in infected cells approximately 32 h post-infection. PEPSCAN epitope mapping suggested that all the MAbs react with a region of the dengue 2 virus core protein (9RNTPFNMLKRE19) which is adjacent to a putative nuclear localization sequence (6KKAR9) and spans a possible second site for the initiation of synthesis of core protein (12PFN↓MLKR18).
TL;DR: The PROLOG program extensively searches for potential attacks in a simple rule-based model of the system and is suggested that this program is capable of extended operations in other areas when security or safety flaws are to be investigated.
TL;DR: It is shown how to construct a perceptron with two hidden layers for multivariate function approximation, which can perform function approximation in the same manner as networks based on Gaussian potential functions, by linear combination of local functions.
Abstract: Mathematical theorems establish the existence of feedforward multilayered neural networks, based on neurons with sigmoidal transfer functions, that approximate arbitrarily well any continuous multivariate function. However, these theorems do not provide any hint on how to find the network parameters in practice. It is shown how to construct a perceptron with two hidden layers for multivariate function approximation. Such a network can perform function approximation in the same manner as networks based on Gaussian potential functions, by linear combination of local functions. >
TL;DR: In this article, the authors demonstrate how action research may be applied to graduate management research programs and discuss issues of conducting action research within a graduate Management Research Program (MRSP).
Abstract: The purpose of this paper is to demonstrate how action research may be applied to graduate management research programs. After distinguishing action research from traditional research and establishing that the former is more appropriate for developing managerial competencies than the latter, the paper discusses issues of conducting action research within a graduate management research program. These issues centre on the key concept of distinguishing between action research project and a thesis action research project. Distinctions between action research projects at Masters and PhD levels are noted. It is argued that ideally the core action research project has to be part of the PhD candidate's full-time work. Future difficulties are canvassed.
TL;DR: The consistency of Prony's method and of related algorithms based on maximum likelihood is discussed as the number of observations n → ∞ by considering the simplest possible models for fitting sums of exponentials to observed data.
Abstract: Modifications of Prony's classical technique for estimating rate constants in exponential fitting problems have many contemporary applications. In this article the consistency of Prony's method and of related algorithms based on maximum likelihood is discussed as the number of observations n → ∞ by considering the simplest possible models for fitting sums of exponentials to observed data. Two sampling regimes are relevant, corresponding to transient problems and problems of frequency estimation, each of which is associated with rather different kinds of behavior. The general pattern is that the stronger results are obtained for the frequency estimation problem. However, the algorithms considered are all scaling dependent and consistency is not automatic. A new feature that emerges is the importance of an appropriate choice of scale in order to ensure consistency of the estimates in certain cases. The tentative conclusion is that algorithms referred to as Objective function Reweighting Algorithms ...
TL;DR: A comparison of the sequence of the dengue-2 16681 virus with that of the candidate vaccine strain derived from it identified 53 of the 10,723 nucleotides which differed between the strains.
TL;DR: Differences were found in gait symmetry measures, with the obese displaying asymmetry in step length and step factor and in all cases, the right limb was favoured.
Abstract: The gait patterns of 10 obese and four normal-weight, prepubertal children were used to evaluate characteristics of varying weight groups. Analyses of temporal and distance parameters were conducted on representative gait cycles at slow, normal and fast speeds of walking. Obese subjects showed longer cycle duration (P less than 0.001), lower cadence (P less than 0.001), lower relative velocity (statures/sec) (P less than 0.001) and a longer stance period (P less than 0.001) than normal-weight subjects. Differences were also found in gait symmetry measures, with the obese displaying asymmetry in step length and step factor. In all cases, the right limb was favoured. Obese subjects displayed greatest instability at the slow speed of walking. Language: en
TL;DR: The Science Laboratory Environment Inventory (SLEI) as discussed by the authors assesses students' or teachers' perceptions of five dimensions of actual or preferred classroom environment, namely, Student Cohesiveness, Open-Endedness, Integration, Rule Clarity, and Material Environment.
Abstract: A strong tradition in educational research has involved several widely-used instruments assessing student or teacher perceptions of characteristics of actual or preferred classroom psychosocial environment. Existing instruments, however, are unsuitable for one of the most important settings in science teaching, namely, the science laboratory class. Consequently, the present research aimed to develop and validate a new instrument, the Science Laboratory Environment Inventory (SLEI), which is specifically suited to science laboratory environments at the higher education level. The SLEI assesses students' or teachers' perceptions of five dimensions of actual or preferred classroom environment, namely, Student Cohesiveness, Open-Endedness, Integration, Rule Clarity, and Material Environment. A distinctive feature of the design of the study was that the instrument was field tested and validated cross-nationally in six different countries, namely, the USA, Canada, Australia, England, Israel, and Nigeria. The total sample consisted of 1720 students in 71 university laboratory classes. Various item and factor analyses guided the evolution of a refined version, and attested to each SLEI scale's internal consistency reliability, discriminant validity, factorial validity, predictive validity (i.e., ability to predict student outcomes), and ability to differentiate between the perceptions of students in different classes. An important finding was that the SLEI is equally valid for use in its actual and preferred versions, and for the individual or the class mean as the unit of analysis. As well, separate within-country analyses confirmed the validity and usefulness of the SLEI in each of the six countries involved in the field testing. Overall, the study attested to the general advantages of employing cross-national designs in learning environment research.
TL;DR: In this paper, the present state of the design of spectacle lenses with respect to minimizing the side effects associated with their wear is considered, including spherical lens design, progressive addition lenses, and material assumptions of conventional lens design.
Abstract: This review considers the present state of the design of spectacle lenses with respect to minimizing the side effects that are associated with their wear. Topics include spherical lens design, aspheric lens design, progressive addition lenses, spectacle lens materials, assumptions of conventional lens design, and practical assessment of spectacle lens design. Future possibilities in the manufacture of spectacle lenses are discussed briefly.
TL;DR: In this paper, the role of radiation-induced apoptosis in MADCaT was discussed, and its role in a MADCAT (Mitosis-opoptosis-differentiation-calcium Toxicity) scheme of Cytotoxicity Mechanisms.
Abstract: (1992). Radiation-induced Apoptosis: Its Role in a MADCaT (Mitosis-opoptosis-differentiation-calcium Toxicity) Scheme of Cytotoxicity Mechanisms. International Journal of Radiation Biology: Vol. 62, No. 2, pp. 145-152.
TL;DR: Routine use of the ELISA would alert authorities to future outbreaks of Chikungunya virus infection and avoid admission to hospital of patients with a non-life-threatening viral disease.
Abstract: During 1984, 1548 children were admitted to the Yangon [Rangoon] Children's Hospital in Myanmar [Burma] with haemorrhagic fever. No evidence of recent dengue infection was found in 577 of the 803 children from whom paired sera were obtained, raising the possibility of reappearance of Chikungunya virus infection in Myanmar. An enzyme-linked immunosorbent assay ( elisa ) for the detection of anti-Chikungunya virus immunoglobulin M (IgM) antibody was prepared and standardized using only reagents which are commercially available or which could be prepared without the use of sophisticated equipment. While there was 90% agreement between haemagglutination inhibition (HI) tests and the IgM elisa in the diagnosis of acute Chikungunya virus infections, 12 additional patients with stationary anti-Chikungunya virus HI antibody titres could be identified as having acute Chikungunya infections using the elisa . Furthermore, the elisa could identify twice as many patients ( 31 103 ) at the time of admission to hospital as the HI test ( 15 103 ). There was no false positive IgM reaction with the elisa which could be attributed to the presence of rheumatoid factor. Using the test, 103 of a sample of 163 children who presented to the Yangon Children's Hospital with fever/haemorrhagic fever were diagnosed as Chikungunya patients, 4 had possible dual Chikungunya and dengue infections, 16 had dengue, 30 had neither Chikungunya nor dengue infections, and a definitive diagnosis could not be made for 10 patients. Routine use of the elisa would alert authorities to future outbreaks of Chikungunya virus infection and avoid admission to hospital of patients with a non-life-threatening viral disease.
TL;DR: In this paper, the locus of spatial inflection points, a twisted cubic curve common to three ruled quadric surfaces, is derived in a coordinate system attached to the fixed axode.
TL;DR: No significant genetic differentiation was observed among most populations from the GBR, consistent with the high gene exchange expected in this highly connected reef system, however, significant differentiation resulting from differences in the frequencies of less common alleles between the North-Central GBR and South GBR (Swain region) were observed.
Abstract: Large genetic differences were observed among the Great Barrier Reef (GBR), Fiji and Philippine populations of Tridacna derasa (Roding) sampled in 1989 and 1990 (Nei's unbiased genetic distance, D,=0.137 to 0.341). This result contrasted strongly with the low genetic distance (D=0.032) reported previously for the giant clam T. maxima over similar geographical scales. No significant genetic differentiation was observed among most populations from the GBR (mean D=0.007), consistent with the high gene exchange expected in this highly connected reef system. However, significant differentiation resulting from differences in the frequencies of less common alleles between the North-Central GBR and South GBR (Swain region) were observed. Historical isolation of blocks of the Central Indo-West Pacific from the GBR and present-day restrictions to gene exchange between the GBR, Fiji and the Philippines as a result of oceanographic current patterns, were thought to be responsible for the high degree of genetic differentiation of T. derasa populations. The relevance of these findings to clam mariculture and reef restocking are briefly discussed.
30 Aug 1992
TL;DR: The author presents a nonlinear type of smoother related to mathematical morphology which meets (modified) ' scale-space axioms' and also generates a 'scale-space' which is full-plane and preserves the positions of features.
Abstract: Scale-space is an important recent concept used in image processing and pattern recognition. Traditional scale-space is generated by a linear smoothing operation. The author presents a nonlinear type of smoother related to mathematical morphology which meets (modified) 'scale-space axioms' and also generates a 'scale-space'. This scale-space is full-plane and preserves the positions of features. >
TL;DR: The results establish the validity, accuracy and precision of MFBIA for the assessment of both TBW and ECW.
TL;DR: Two analytical methods, namely, spectrolluorometry and hydride generation atomic absorption spectrometry (HG-AAS), were used for determining the levels of selenium in food materials.