Showing papers by "La Trobe University published in 1999"

Optical dating of single and multiple grains of quartz from jinmium rock shelter, northern australia: part i, experimental design and statistical models*

Abstract: Jinmium rock shelter is famous for the claims made by Fullagar et al. (1996) for the early human colonization and ancient rock art of northern Australia. These claims were based on thermo-luminescence ages obtained for the artefact-bearing quartz sediments that form the floor deposit at the site. In this paper, we outline the background to the optical dating programme at Jinmium, and describe the experimental design and statistical methods used to obtain optical ages from single grains of quartz sand. The results, interpretations, and implications of this dating programme are reported in a companion paper (Roberts et al. 1999, this volume).

Relations between teachers' approaches to teaching and students' approaches to learning

Abstract: This paper reports on an empirical study which shows that qualitatively different approaches to teaching are associated with qualitatively different approaches to learning More specifically, the results indicate that in the classes where teachers describe their approach to teaching as having a focus on what they do and on transmitting knowledge, students are more likely to report that they adopt a surface approach to the learning of that subject Con- versely, but less strongly, in the classes where students report adopting significantly deeper approaches to learning, teaching staff report adopting approaches to teaching that are more oriented towards students and to changing the students conceptions The study made use of a teaching approach inventory derived from interviews with academic staff, and a modified approach to learning questionnaire These conclusions are derived from a factor and cluster analysis of 48 classes (involving 46 science teachers and 3956 science students) in Australian universities The results complete a chain of relations from teacher thinking to the outcomes of student learning Previous studies have shown relations between teachers' conceptions of teaching and learning and their approaches to teaching Numerous studies have shown corre- lations between students' deeper approaches to learning and higher quality learning outcomes The results reported here link these two sets of studies They also highlight the importance, in attempts to improve the quality of student learning, of discouraging teacher-focused transmis- sion teaching and encouraging higher quality, conceptual change/student-focused approaches to teaching

Associations between corporate characteristics and disclosure levels in annual reports: a meta-analysis

Abstract: Accounting researchers have investigated associations between corporate characteristics and disclosures in corporate annual reports since 1961. Findings have consistently shown corporate size and listing status to be significantly associated with disclosure levels, while mixed results have been reported for leverage, profitability, and audit firm size. The purpose of the present paper is to integrate prior disclosure studies and to identify the underlying factors that moderate the apparent variation in results. A meta-analysis of 29 studies confirms significant and positive relationships between disclosure levels and corporate size, listing status and leverage. No significant association is found between corporate profitability or size of audit firm, with aggregate disclosure levels. This study also found that in addition to sampling error, the results are moderated by differences in disclosure index construction, differences in definition of the explanatory variables, and differences in research settings.

Heritable variation and evolution under favourable and unfavourable conditions.

Abstract: Genetic variability in quantitative traits can change as a direct response to the environmental conditions in which they are expressed. Consequently, similar selection in different environments might not be equally effective in leading to adaptation. Several hypotheses, including recent ones that focus on the historical impact of selection on populations, predict that the expression of genetic variation will increase in unfavourable conditions. However, other hypotheses lead to the opposite prediction. Although a consensus is unlikely, recent Drosophila and bird studies suggest consistent trends for morphological traits under particular conditions.

The effect of unemployment on mental health

Abstract: Sixteen recent longitudinal studies are examined for evidence relevant to the claim that a change to one’s employment status aVects one’s mental health. Although there were limitations to the set of studies examined, most of the studies supported this claimed relationship. Examination was then made of the size of this eVect. In carrying out this examination, the set of study results were divided into two categories: (a) those addressing the question of the extent to which gaining employment impacts on mental well-being; (b) those addressing the question of the extent to which employment loss impacts on mental health. The meta-analyses indicated that there was a weighted eVect size of .54 for the erst question, and a smaller weighted eVect size (.36) for the latter question. Depressive aVect is probably the most frequently studied psychological variable among unemployed people. In the 10 years since O’Brien (1986) reviewed the literature on the psychological eVects of unemployment, 16 longitudinal studies have appeared in MEDLINE or PSYCLIT to complement the large number of cross-sectional studies which have compared employed and unemployed persons on various measures of personality, mood and psychiatric vulnerability. With the addition of these recent longitudinal studies it is possible to attempt to summarize what is known about the mental health consequences of unemployment, even while acknowledging certain methodological issues that continue to constrain the study of this aspect of the psychology of unemployment. In this article we review what is known about the mental health eVects of unemployment. We do not pay detailed attention to personal and contextual factors which might limit the validity of any generalizations about the nature and extent of the relationship between unemployment and negative aVect, as our main aim is to consider the scientiec evidence for the claim that job loss generally aVects the mental health of the unemployed. A second aim of the paper is to describe the size of any demonstrated eVect.

Analysis of new and existing methods of reducing intercarrier interference due to carrier frequency offset in OFDM

Abstract: Orthogonal frequency division multiplexing (OFDM) is very sensitive to frequency errors caused by frequency differences between transmitter and receiver local oscillators. This sensitivity is analyzed in terms of the complex weighting coefficients which give the contribution of each transmitter subcarrier to each demodulated subcarrier. Previously described windowing and self intercarrier interference (ICI) cancellation methods are analyzed in terms of these weighting coefficients. New ICI cancellation schemes with very much improved performance are described. A condition for orthogonality of windowing schemes is derived in terms of the discrete Fourier transform (DFT) of the windowing function.

Electricity price short-term forecasting using artificial neural networks

Abstract: This paper presents the system marginal price (SMP) short-term forecasting implementation using the artificial neural networks (ANN) computing technique. The described approach uses the three-layered ANN paradigm with backpropagation. The retrospective SMP real-world data, acquired from the deregulated Victorian power system, was used for training and testing the ANN. The results presented in this paper confirm considerable value of the ANN based approach in forecasting the SMP.

Geometric integration using discrete gradients

Abstract: This paper discusses the discrete analogue of the gradient of a function and shows how discrete gradients can be used in the numerical integration of ordinary differential equations (ODEs). Given a...

The Promise of Comparative Genomics in Mammals

Abstract: Dense genetic maps of human, mouse, and rat genomes that are based on coding genes and on microsatellite and single-nucleotide polymorphism markers have been complemented by precise gene homolog alignment with moderate-resolution maps of livestock, companion animals, and additional mammal species. Comparative genetic assessment expands the utility of these maps in gene discovery, in functional genomics, and in tracking the evolutionary forces that sculpted the genome organization of modern mammalian species.

Volatile and Contradictory Punishment

Abstract: Criminologists have recognized that contemporary penal policy and practice are characterized by an unusual degree of incoherence and volatility. Garland (1996) sees this as evidence of the limits of the sovereign state, Simon (1995) as a sign of the postmodern disintegration of modern penality, while others explain it in terms of the emergence of advanced liberalism and neo-liberal politics. This article argues that such incoherence is better understood in terms of the contradictory elements of New Right politics. The nature of this political alliance extends the repertory of penality simultaneously in `nostalgic' (neo-conservative) and `innovative' (neo-liberal) directions, resulting in considerable incoherence. At the same time, the conservative orientation to state authoritarian strategies and the neo-liberal leaning toward market and private sector governance, could account for the volatility. This brings into question some of the accounts based on more fundamental social transformations.

Using the science writing heuristic as a tool for learning from laboratory investigations in secondary science

Abstract: This article presents and discusses preliminary research on a new heuristic tool for learning from laboratory activities in secondary science. The tool, called the science writing heuristic, can be used by teachers as a framework from which to design classroom activities. Theoretically, the science writing heuristic represents a bridge between traditional laboratory reports and types of writing that promote personal construction of meaning. Two eighth-grade classes participated in using the science writing heuristic during an 8-week stream study. The teacher and one of the researchers collaboratively developed activities based on the science writing heuristic that the teacher implemented. Nineteen target students were studied in depth. Characteristics of report writing and students' understanding of the nature of science were investigated, using interpretive techniques. There is evidence that use of the science writing heuristic facilitated students to generate meaning from data, make connections among procedures, data, evidence, and claims, and engage in metacognition. Students' vague understandings of the nature of science at the beginning of the study were modified to more complex, rich, and specific understandings. The implications of the study for writing in science classrooms is discussed. © 1999 John Wiley & Sons, Inc. J Res Sci Teach 36: 1065–1084, 1999

The relationship between spot and futures prices: Evidence from the crude oil market

Abstract: This article examines the relationship between the spot and futures prices of WTI crude oil using a sample of daily data. Linear causality testing reveals that futures prices lead spot prices, but nonlinear causality testing reveals a bidirectional effect. This result suggests that both spot and futures markets react simultaneously to new information. © 1999 John Wiley & Sons, Inc. Jrl Fut Mark 19: 175–193, 1999

Muscular Strength Training Is Associated With Low Arterial Compliance and High Pulse Pressure

Abstract: Aerobic exercise training increases arterial compliance and reduces systolic blood pressure, but the effects of muscular strength training on arterial mechanical properties are unknown We compared blood pressure, whole body arterial compliance, aortic impedance, aortic stiffness (measured by beta-index and carotid pulse pressure divided by normalized systolic expansion [Ep]), pulse wave velocity, and left ventricular parameters in 19 muscular strength-trained athletes (mean+/-SD age, 26+/-4 years) and 19 sedentary controls (26+/-5 years) Subjects were healthy, non-steroid-using, nonsmoking males, and athletes had been engaged in a strength-training program with no aerobic component for a minimum of 12 months There was no difference in maximum oxygen consumption between groups, but handgrip strength (mean+/-SEM, 44+/-2 versus 56+/-2 kg; P<001) and left ventricular mass (168+/-8 versus 190+/-8 g; P<005) were greater in athletes Arterial stiffness was higher in athletes, as evidenced by lower whole body arterial compliance (040+/-004 versus 054+/-004 arbitrary compliance units; P=001), higher aortic characteristic impedance (155+/-013 versus 118+/-008 mm Hg s cm-1; P<005), beta-index (46+/-02 versus 38+/-04; P<0 05), and ln Ep (1086+/-006 versus 1060+/-008; P<001) Femoral-dorsalis pedis pulse wave velocity was also higher in the athletes, but carotid-femoral pulse wave velocity was not different Furthermore, both carotid (56+/-3 versus 44+/-2 mm Hg; P<0001) and brachial (60+/-3 versus 50+/-2 mm Hg; P<001) pulse pressures were higher in the athletes, but mean arterial pressure and resting heart rate did not differ between groups These data indicate that both the proximal aorta and the leg arteries are stiffer in strength-trained individuals and contribute to a higher cardiac afterload

Desiccation and starvation resistance in Drosophila: patterns of variation at the species, population and intrapopulation levels

Abstract: A substantial number of Drosophila studies have investigated variation in desiccation and starvation resistance, providing an opportunity to test for consistent patterns of direct and correlated responses across studies and across the species and population levels. In general, responses to laboratory selection for these traits in D. melanogaster are rapid and indicate abundant genetic variation in populations. However, slower responses to selection for desiccation resistance occur in other species including D. simulans. Clines suggest adaptive divergence although specific selection pressures have not been documented empirically. Drosophila species differ markedly in desiccation and starvation resistance and there is also marked variation within species for desiccation resistance that may be linked to local climatic conditions. Laboratory selection experiments on starvation resistance in D. melanogaster suggest that changes in lipid content are largely responsible for resistance variation but this factor may be less important in explaining variation among species. For desiccation, lines with increased resistance show reduced rates of water loss but no changes in the minimum water content that flies can tolerate. Changes in life history traits are sometimes associated with altered levels of stress resistance. Increased starvation resistance is associated with longer development time and reduced early age reproduction in different studies. However, other associations are inconsistent between studies as in the case of stress resistance changing following selection for longevity. Multiple mechanisms may underlie genetic variation in stress resistance and future studies should address the evolutionary importance of the different mechanisms at the population and species levels.

Comparative painting reveals strong chromosome homology over 80 million years of bird evolution.

Abstract: Chickens and the great flightless emu belong to two distantly related orders of birds in the carinate and ratite subclasses that diverged at least 80 million years ago. In the first ZOO-FISH study between bird species, we hybridized single chromosome paints from the chicken (Gallus domesticus) onto the emu chromosomes. We found that the nine macrochromosomes show remarkable homology between the two species, indicating strong conservation of karyotype through evolution. One chicken macrochromosome (4) was represented by a macro- and a microchromosome in the emu, suggesting that microchromosomes and macrochromosomes are interconvertible. The chicken Z chromosome paint hybridized to the emu Z and most of the W, confirming that ratite sex chromosomes are largely homologous; the centromeric region of the W which hybridized weakly may represent the location of the sex determining gene(s).

Isoflavones from red clover improve systemic arterial compliance but not plasma lipids in menopausal women.

Abstract: The possibility that the heightened cardiovascular risk associated with the menopause can be reduced by increasing dietary isoflavone intake was tested in 17 women by measuring arterial compliance, an index of the elasticity of large arteries such as the thoracic aorta. Compliance diminishes with age and menopause. An initial 3- to 4-week run-in period and a 5-week placebo period were followed by two 5-week periods of active treatment with 40 mg and then 80 mg isoflavones derived from red clover containing genistein, daidzein, biochanin, and formononetin in 14 and 13 women, respectively, with 3 others serving as placebo controls throughout. Arterial compliance, measured by ultrasound as a pressure (carotid artery) and volume (outflow into aorta) relationship, was determined after each period; plasma lipids were measured twice during each period. Urinary output of isoflavones was also determined. Arterial compliance rose by 23% relative to that during the placebo period with the 80-mg isoflavone dose and slightly less with the 40-mg dose (mean +/- SEM: placebo, .197 +/- .015; 40 mg, .237 +/- 0.007; 80 mg, .244 +/- .014). In the three women receiving continuous placebo, compliance was .16 +/- .022, similar to that during the run-in period for the remaining subjects (.17 +/- .021) [corrected]. ANOVA showed a significant (P = < 0.001) difference between treatments; by Bonferroni multiple comparisons and by paired t test, differences were significant between placebo and 40- and 80-mg isoflavone doses (by paired t test: P = 0.039 for placebo vs. 40 mg; P = 0.018 for placebo vs. 80 mg). Plasma lipids were not significantly affected. An important cardiovascular risk factor, arterial compliance, which diminishes with menopause, was significantly improved with red clover isoflavones. As diminished compliance leads to systolic hypertension and may increase left ventricular work, the findings indicate a potential new therapeutic approach for improved cardiovascular function after menopause.

Inhibition of the peroxidative degradation of haem as the basis of action of chloroquine and other quinoline antimalarials.

Abstract: The malaria parasite feeds by degrading haemoglobin in an acidic food vacuole, producing free haem moieties as a by-product. The haem in oxyhaemoglobin is oxidized from the Fe(II) state to the Fe(III) state with the consequent production of an equimolar concentration of H2O2. We have analysed the fate of haem molecules in Plasmodium falciparum-infected erythrocytes and have found that only about one third of the haem is polymerized to form haemozoin. The remainder appears to be degraded by a non-enzymic process which leads to an accumulation of iron in the parasite. A possible route for degradation of the haem is by reacting with H2O2, and we show that, under conditions designed to resemble those found in the food vacuole, i.e., at pH5.2 in the presence of protein, free haem undergoes rapid peroxidative decomposition. Chloroquine and quinacrine are shown to be efficient inhibitors of the peroxidative destruction of haem, while epiquinine, a quinoline compound with very low antimalarial activity, has little inhibitory effect. We also show that chloroquine enhances the association of haem with membranes, while epiquinine inhibits this association, and that treatment of parasitized erythrocytes with chloroquine leads to a build-up of membrane-associated haem in the parasite. We suggest that chloroquine exerts its antimalarial activity by causing a build-up of toxic membrane-associated haem molecules that eventually destroy the integrity of the malaria parasite. We have further shown that resistance-modulating compounds, such as chlorpromazine, interact with haem and efficiently inhibit its degradation. This may explain the weak antimalarial activities of these compounds.

Optical dating of single and multiple grains of quartz from jinmium rock shelter, northern australia: part ii, results and implications*

Abstract: Quartz sediments from the floor deposit at Jinmium Rock Shelter have been investigated using the multiple-grain and single-grain optical dating methods described by Galbraith et al. (1999, this volume). Here we present the results of this dating programme and argue that the artefact-bearing sediments were deposited within the last 10 000 years. This time interval is consistent with the radiocarbon chronology but is much younger than previous claims for initial human occupation during the Pleistocene. Analysis of individual grains revealed also that the characteristic saturation doses of some grains are unusually high, which may permit dating of deposits older than a few hundred thousand years. Such grain-to-grain differences raise doubts, however, about the validity of using multiple-grain samples to investigate the phenomenology of quartz luminescence.

The Structure and Function of Myelin Oligodendrocyte Glycoprotein

Abstract: Myelin oligodendrocyte glycoprotein (MOG) is a quantitatively minor component of CNS myelin whose function remains relatively unknown. As MOG is an autoantigen capable of producing a demyelinating multiple sclerosis-like disease in mice and rats, much of the research directed toward MOG has been immunological in nature. Although the function of MOG is yet to be elucidated, there is now a relatively large amount of biochemical and molecular data relating to MOG. Here we summarize this information and include our recent findings pertaining to the cloning of the marsupial MOG gene. On the basis of this knowledge we suggest three possible functions for MOG: (a) a cellular adhesive molecule, (b) a regulator of oligodendrocyte microtubule stability, and (c) a mediator of interactions between myelin and the immune system, in particular, the complement cascade. Given that antibodies to MOG and to the myelin-specific glycolipid galactocerebroside (Gal-C) both activate the same signaling pathway leading to MBP degradation, we propose that there is a direct interaction between the membrane-associated regions of MOG and Gal-C. Such an interaction may have important consequences regarding the membrane topology and function of both molecules. Finally, we examine how polymorphisms and/or mutations to the MOG gene could contribute to the pathogenesis of multiple sclerosis.

Hyperbaric or normobaric oxygen for acute carbon monoxide poisoning: a randomised controlled clinical trial.

Abstract: OBJECTIVE: To assess neurological sequelae in patients with all grades of carbon monoxide (CO) poisoning after treatment with hyperbaric oxygen (HBO) and normobaric oxygen (NBO). DESIGN: Randomised controlled double-blind trial, including an extended series of neuropsychological tests and sham treatments in a multiplace hyperbaric chamber for patients treated with NBO. SETTING: The multiplace hyperbaric chamber at the Alfred Hospital, a university-attached quarternary referral centre in Melbourne providing the only hyperbaric service in the State of Victoria. PATIENTS: All patients referred with CO poisoning between 1 September 1993 and 30 December 1995, irrespective of severity of poisoning. Pregnant women, children, burns victims and those refusing consent were excluded. INTERVENTION: Daily 100-minute treatments with 100% oxygen in a hyperbaric chamber--60 minutes at 2.8 atmospheres absolute for the HBO group and at 1.0 atmosphere absolute for the NBO group--for three days (or for six days for patients who were clinically abnormal or had poor neuropsychological outcome after three treatments). Both groups received continuous high flow oxygen between treatments. MAIN OUTCOME MEASURES: Neuropsychological performance at completion of treatment, and at one month where possible. RESULTS: More patients in the HBO group required additional treatments (28% v. 15%, P = 0.01 for all patients; 35% v. 13%, P = 0.001 for severely poisoned patients). HBO patients had a worse outcome in the learning test at completion of treatment (P = 0.01 for all patients; P = 0.005 for severely poisoned patients) and a greater number of abnormal test results at completion of treatment (P = 0.02 for all patients; P = 0.008 for severely poisoned patients). A greater percentage of severely poisoned patients in the HBO group had a poor outcome at completion of treatment (P = 0.03). Delayed neurological sequelae were restricted to HBO patients (P = 0.03). No outcome measure was worse in the NBO group. CONCLUSION: In this trial, in which both groups received high doses of oxygen, HBO therapy did not benefit, and may have worsened, the outcome. We cannot recommend its use in CO poisoning. Language: en

An exploratory study of patients' perceptions, memories and experiences of an intensive care unit.

Abstract: In the research reported, 298 patients were asked to describe their memories of the Royal Melbourne Hospital's intensive care unit (ICU). The data were collected by either self-reported questionnaires or structured interviews and examined from a bio-psycho-social perspective using both qualitative and quantitative methods. These recollections demonstrate that the close surveillance by both technological support and health care practitioners provide many patients and their families with a feeling of safety. Patients' memories of ICU also highlighted the presence of power relations which are inherent in clinical practice. This paper provides examples of actions and remarks within ICU that were not only remembered by patients and their families but also continued to effect patients 6 months after their discharge. The data in this research indicate that some of the psychological problems experienced after discharge may have been prevented by improved communication between staff and patients in ICU. This study also demonstrated the importance of providing feedback to the nurses working in ICU. This feedback raised awareness of patients' perceptions of both ICU itself and the behaviour of the staff. It also reminded staff that some patients remember everything about their admission of ICU. The data indicate that while patients found the presence of good communication in ICU both therapeutic and reassuring, they found the lack of good communication distressing. Poor communication not only caused anxiety while the patient was in ICU but also contributed to less than optimal recoveries after discharge. Finally, it will be argued that the provision of information from nurses not only diminished feelings of anxiety but also empowered patients to become involved in decisions about their care.

Epidemiology of injury in elite and subelite female gymnasts: a comparison of retrospective and prospective findings.

Abstract: OBJECTIVES: An 18 month prospective injury survey was conducted on 64 Australian elite and subelite female gymnasts. The aims were to determine the rate of injury, anatomical location, and types of injury incurred by female competitive gymnasts, and to compare the findings with data collected retrospectively from the same sample of gymnasts. METHODS: The gymnasts recorded (weekly) in an injury record booklet the number of hours trained and information on any injuries suffered over that week. RESULTS: The sample reported 349 injuries, a rate of 5.45 per person (6.29 for the elite and 4.95 for subelite gymnasts) over the 18 month survey. Injuries to the ankle and foot (31.2%) were the most commonly reported, followed by the lower back (14.9%). The most prevalent type of injury were sprains (29.7%), followed by strains (23.2%), and growth plate injuries (12.3%). The elite gymnasts reported that, for each injury, they missed fewer training sessions (p = 0.01), but modified more sessions (p = 0.0001) than their subelite counterparts. Further, the elite gymnasts spent 21.0% of the year training at less than full capacity because of injury. Although a significantly higher number of injuries were recorded in the prospective study (p = 0.0004), no differences were found between the distribution of injury by anatomical location or type between the two methods of data collection. CONCLUSIONS: The findings have important implications in terms of training procedures and periodic screening of gymnasts.

The Central Siberian Origin for Native American Y Chromosomes

Abstract: Y chromosomal DNA polymorphisms were used to investigate Pleistocene male migrations to the American continent. In a worldwide sample of 306 men, we obtained 32 haplotypes constructed with the variation found in 30 distinct polymorphic sites. The major Y haplotype present in most Native Americans was traced back to recent ancestors common with Siberians, namely, the Kets and Altaians from the Yenissey River Basin and Altai Mountains, respectively. Going further back, the next common ancestor gave rise also to Caucasoid Y chromosomes, probably from the central Eurasian region. This study, therefore, suggests a predominantly central Siberian origin for Native American paternal lineages for those who could have migrated to the Americas during the Upper Pleistocene.

Role for yeast inhibitor of apoptosis (IAP)-like proteins in cell division

Abstract: Inhibitors of apoptosis (IAPs) are a family of proteins that bear baculoviral IAP repeats (BIRs) and regulate apoptosis in vertebrates and Drosophila melanogaster. The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe both encode a single IAP, designated BIR1 and bir1, respectively, each of which bears two BIRs. In rich medium, BIR1 mutant S. cerevisiae underwent normal vegetative growth and mitosis. Under starvation conditions, however, BIR1 mutant diploids formed spores inefficiently, instead undergoing pseudohyphal differentiation. Most spores that did form failed to survive beyond two divisions after germination. bir1 mutant S. pombe spores also died in the early divisions after spore germination and became blocked at the metaphase/anaphase transition because of an inability to elongate their mitotic spindle. Rather than inhibiting caspase-mediated cell death, yeast IAP proteins have roles in cell division and appear to act in a similar way to the IAPs from Caenorhabditis elegans and the mammalian IAP Survivin.