Showing papers by "Monash University published in 2000"

Embryonic stem cell lines from human blastocysts: somatic differentiation in vitro.

Abstract: We describe the derivation of pluripotent embryonic stem (ES) cells from human blastocysts. Two diploid ES cell lines have been cultivated in vitro for extended periods while maintaining expression of markers characteristic of pluripotent primate cells. Human ES cells express the transcription factor Oct-4, essential for development of pluripotential cells in the mouse. When grafted into SCID mice, both lines give rise to teratomas containing derivatives of all three embryonic germ layers. Both cell lines differentiate in vitro into extraembryonic and somatic cell lineages. Neural progenitor cells may be isolated from differentiating ES cell cultures and induced to form mature neurons. Embryonic stem cells provide a model to study early human embryology, an investigational tool for discovery of novel growth factors and medicines, and a potential source of cells for use in transplantation therapy.

Efficient genetic markers for population biology.

Abstract: Population genetics has come of age. Three important components have come together: efficient techniques to examine informative segments of DNA, statistics to analyse DNA data and the availability of easy-to-use computer packages. Single-locus genetic markers and those that produce gene genealogies yield information that is truly comparable among studies. These markers answer biological questions most efficiently and also contribute to much broader investigations of evolutionary, population and conservation biology. For these reasons, single-locus and genealogical markers should be the focus of the intensive genetic data collection that has begun owing to the power of genetics in population biology.

Nimrod/G: an architecture for a resource management and scheduling system in a global computational grid

Abstract: The availability of powerful microprocessors and high-speed networks as commodity components has enabled high-performance computing on distributed systems (wide-area cluster computing). In this environment, as the resources are usually distributed geographically at various levels (department, enterprise or worldwide), there is a great challenge in integrating, coordinating and presenting them as a single resource to the user, thus forming a computational grid. Another challenge comes from the distributed ownership of resources, with each resource having its own access policy, cost and mechanism. The proposed Nimrod/G grid-enabled resource management and scheduling system builds on our earlier work on Nimrod (D. Abramson et al., 1994, 1995, 1997, 2000) and follows a modular and component-based architecture enabling extensibility, portability, ease of development, and interoperability of independently developed components. It uses the GUSTO (GlobUS TOolkit) services and can be easily extended to operate with any other emerging grid middleware services. It focuses on the management and scheduling of computations over dynamic resources scattered geographically across the Internet at department, enterprise or global levels, with particular emphasis on developing scheduling schemes based on the concept of computational economy for a real testbed, namely the Globus testbed (GUSTO).

Relational Autonomy: Feminist Perspectives on Autonomy, Agency, and the Social Self

Abstract: Introduction: Autonomy refigured PART 1: AUTONOMY AND THE SOCIAL 1. Autonomy, social disruption and women 2. Autonomy and the social self 3. Feeling crazy: self worth and the social character of responsibility 4. Autonomy and the feminist intuition 5. Individuals, responsibility and the philosophical imagination 6. Imagining oneself otherwise 7. Intersectional identity and the authentic self?: Opposites attract 8. The perversion of autonomy and the subjection of women: discourses of social advocacy at century's end PART II: RELATIONAL AUTONOMY IN CONTEXT 9. Choice and control in feminist bioethics 10. Autonomy and interdependence: quandaries in genetic decision-making 11. Relational autonomy, self-trust, and health care for patients who are oppressed 12. Relational autonomy and freedom of expression

Differential tumor surveillance by natural killer (NK) and NKT cells

Abstract: Natural tumor surveillance capabilities of the host were investigated in six different mouse tumor models where endogenous interleukin (IL)-12 does or does not dictate the efficiency of the innate immune response. Gene-targeted and lymphocyte subset–depleted mice were used to establish the relative importance of natural killer (NK) and NK1.1+ T (NKT) cells in protection from tumor initiation and metastasis. In the models examined, CD3− NK cells were responsible for tumor rejection and protection from metastasis in models where control of major histocompatibility complex class I–deficient tumors was independent of IL-12. A protective role for NKT cells was only observed when tumor rejection required endogenous IL-12 activity. In particular, T cell receptor Jα281 gene-targeted mice confirmed a critical function for NKT cells in protection from spontaneous tumors initiated by the chemical carcinogen, methylcholanthrene. This is the first description of an antitumor function for NKT cells in the absence of exogenously administered potent stimulators such as IL-12 or α-galactosylceramide.

Discretionary-Accruals Models and Audit Qualifications

Abstract: The primary objective of this study is to evaluate empirically the ability of two cross-sectional models, the Cross-Sectional Jones Model and the Cross-Sectional Modified Jones Model, to detect earnings management vis-a-vis their time-series counterparts. The motivation follows because these two cross-sectional models have not been formally evaluated by prior research, and because their use offers substantial advantages to investors and researchers over their time-series counterparts. A secondary objective is to assess the robustness of findings of prior studies assessing discretionary-accruals models using our new sample and research method, which controls for potential research confounds. The evaluation involves examining the association between discretionary accruals and audit qualifications, using a sample of 166 distinct firms with qualified audit reports and a matched-pair control sample with clean audit reports. An association between large discretionary accruals generated by a model and an audit qualification provides evidence on the ability of the model to detect earnings management. Results from univariate tests that do not control for potential research confounds show that all models, except the DeAngelo Model, are consistently successful in discriminating between firms that manage earnings. Once potential research confounds are controlled, however, only the two cross-sectional models are able to detect earnings management. This last result, which highlights the importance of controlling for research confounds in earnings management studies using carefully selected samples, implies that the cross-sectional models are superior to their time-series counterparts. This finding is particularly important for future earnings management research because using a cross-sectional model rather than its time-series counterpart should result in a larger sample size that is less subject to a survivorship bias, and will also allow examining samples of firms with short history.

Aromatase-deficient (ArKO) mice have a phenotype of increased adiposity

Abstract: The aromatase-knockout (ArKO) mouse provides a useful model to examine the role that estrogens play in development and homeostasis in mammals. Lacking a functional Cyp19 gene, which encodes aromatase, the ArKO mouse cannot synthesize endogenous estrogens. We examined the adipose depots of male and female ArKO mice, observing that these animals progressively accumulate significantly more intraabdominal adipose tissue than their wild-type (WT) littermates, reflected in increased adipocyte volume at gonadal and infrarenal sites. This increased adiposity was not due to hyperphagia or reduced resting energy expenditure, but was associated with reduced spontaneous physical activity levels, reduced glucose oxidation, and a decrease in lean body mass. Elevated circulating levels of leptin and cholesterol were present in 1-year-old ArKO mice compared with WT controls, as were elevated insulin levels, although blood glucose levels were unchanged. Associated with these changes, a striking accumulation of lipid droplets was observed in the livers of ArKO animals. Our findings demonstrate an important role for estrogen in the maintenance of lipid homeostasis in both males and females.

Determination of Number of Clusters in K-Means Clustering and Application in Colour Image Segmentation

Abstract: The main disadvantage of the k-means algorithm is that the number of clusters, K, must be supplied as a parameter. In this paper we present a simple validity measure based on the intra-cluster and inter-cluster distance measures which allows the number of clusters to be determined automatically. The basic procedure involves producing all the segmented images for 2 clusters up to Kmax clusters, where Kmax represents an upper limit on the number of clusters. Then our validity measure is calculated to determine which is the best clustering by finding the minimum value for our measure. The validity measure is tested for synthetic images for which the number of clusters in known, and is also implemented for natural images.

A Short Measure of Transformational Leadership

Abstract: This study reports the development of a short measure of transformational leadership: the Global Transformational Leadership scale (GTL). The study sample was 1,440 subordinates who assessed the leader behaviour of 695 branch managers in a large Australian financial organisation. Exploratory and confirmatory factor analysis showed that the GTL measured a single construct of leadership and had satisfactory reliability. Evidence for the convergent and discriminant validity is presented. We conclude that the GTL has a number of potential uses as an assessment and selection tool and in leadership research.

A model of ERP project implementation

Abstract: Problems with the implementation of ERP systems are well documented. Although companies spend millions on ERP packages and the implementation process, there is extensive evidence that they experien...

Perforin-mediated cytotoxicity is critical for surveillance of spontaneous lymphoma

Abstract: Immune surveillance by cytotoxic lymphocytes against cancer has been postulated for decades, but direct evidence for the role of cytotoxic lymphocytes in protecting against spontaneous malignancy has been lacking. As the rejection of many experimental cancers by cytotoxic T lymphocytes and natural killer cells is dependent on the pore-forming protein perforin (pfp), we examined pfp-deficient mice for increased cancer susceptibility. Here we show that pfp-deficient mice have a high incidence of malignancy in distinct lymphoid cell lineages (T, B, NKT), indicating a specific requirement for pfp in protection against lymphomagenesis. The susceptibility to lymphoma was accentuated by simultaneous lack of expression of the p53 gene, mutations in which also commonly predispose to human malignancies, including lymphoma. In contrast, the incidence and age of onset of sarcoma was unaffected in p53-deficient mice. Pfp-deficient mice were at least 1,000-fold more susceptible to these lymphomas when transplanted, compared with immunocompetent mice in which tumor rejection was controlled by CD8(+) T lymphocytes. This study is the first that implicates direct cytotoxicity by lymphocytes in regulating lymphomagenesis.

Dynamic self-organizing maps with controlled growth for knowledge discovery

Abstract: The growing self-organizing map (GSOM) algorithm is presented in detail and the effect of a spread factor, which can be used to measure and control the spread of the GSOM, is investigated. The spread factor is independent of the dimensionality of the data and as such can be used as a controlling measure for generating maps with different dimensionality, which can then be compared and analyzed with better accuracy. The spread factor is also presented as a method of achieving hierarchical clustering of a data set with the GSOM. Such hierarchical clustering allows the data analyst to identify significant and interesting clusters at a higher level of the hierarchy, and continue with finer clustering of the interesting clusters only. Therefore, only a small map is created in the beginning with a low spread factor, which can be generated for even a very large data set. Further analysis is conducted on selected sections of the data and of smaller volume. Therefore, this method facilitates the analysis of even very large data sets.

Nature's heuristics for scheduling jobs on Computational Grids

Abstract: Computational Grid (Grid Computing) is a new paradigm that will drive the computing arena in the new millennium. Unification of globally remote and diverse resources, coupled with the increasing computational needs for Grand Challenge Applications (GCA) and accelerated growth of the Internet and communication technology will further fuel the development of global computational power grids. In this paper, we attempt to address the scheduling of jobs to the geographically distributed computing resources. Conventional wisdom in the field of scheduling is that scheduling problems exhibit such richness and variety that no single scheduling method is sufficient. Heuristics derived from the nature has demonstrated a surprising degree of effectiveness and generality for handling combinatorial optimization problems. This paper begins with an introduction of computational grids followed by a brief description of the three nature's heuristics namely Genetic Algorithm (GA), Simulated Annealing (SA) and Tabu Search (TS). Experimental results using GA are included. We further demonstrate the hybridized usage of the above algorithms that can be applied in a computational grid environment for job scheduling.

A revised model of platelet aggregation

Abstract: In this study we have examined the mechanism of platelet aggregation under physiological flow conditions using an in vitro flow-based platelet aggregation assay and an in vivo rat thrombosis model. Our studies demonstrate an unexpected complexity to the platelet aggregation process in which platelets in flowing blood continuously tether, translocate, and/or detach from the luminal surface of a growing platelet thrombus at both arterial and venous shear rates. Studies of platelets congenitally deficient in von Willebrand factor (vWf) or integrin αIIbβ3 demonstrated a key role for platelet vWf in mediating platelet tethering and translocation, whereas integrin αIIbβ3 mediated cell arrest. Platelet aggregation under flow appears to be a multistep process involving: (a) exposure of vWf on the surface of immobilized platelets; (b) a reversible phase of platelet aggregation mediated by the binding of GPIbα on the surface of free-flowing platelets to vWf on the surface of immobilized platelets; and (c) an irreversible phase of aggregation dependent on integrin αIIbβ3. Studies of platelet thrombus formation in vivo demonstrate that this multistep adhesion mechanism is indispensable for platelet aggregation in arterioles and also appears to promote platelet aggregate formation in venules. Together, our studies demonstrate an important role for platelet vWf in initiating the platelet aggregation process under flow and challenge the currently accepted view that the vWf-GPIbα interaction is exclusively involved in initiating platelet aggregation at elevated shear rates.

Content-based Image Retrieval Using Gabor Texture Features

Abstract: Gabor wavelet proves to be very useful texture analysis and is widely adopted in the literature. In this paper we present a image retrieval method based on Gabor filter. Texture features are found by calculating the mean and variation of the Gabor filtered image. Rotation normalization is realized by a circular shift of the feature elements so that all images have the same dominant direction. The image indexing and retrieval are conducted on textured images and natural images. Experimental results are shown and discussed.

How does male circumcision protect against HIV infection

Abstract: In his otherwise excellent review of the AIDS epidemic in the 21st century, Fauci presented no new strategies for preventing the spread of the disease.1 He made no mention of male circumcision, yet there is now compelling epidemiological evidence from over 40 studies which shows that male circumcision provides significant protection against HIV infection; circumcised males are two to eight times less likely to become infected with HIV.2 Furthermore, circumcision also protects against other sexually transmitted infections, such as syphilis and gonorrhoea,3 4 and since people who have a sexually transmitted infection are two to five times more likely to become infected with HIV,5 circumcision may be even more protective. The most dramatic evidence of the protective effect of circumcision comes from a new study of couples in Uganda who had discordant HIV status; in this study the woman was HIV positive and her male partner was not.6 No new infections occurred among any of the 50 circumcised men over 30 months, whereas 40 of 137 uncircumcised men became infected during this time. Both groups had been given free access to HIV testing, intensive instruction about preventing infection, and free condoms (which were continuously available), but 89% of the men never used condoms, and condom use did not seem to influence the rate of transmission of HIV. These findings should focus the spotlight of scientific attention onto the foreskin. Why does its removal reduce a man's susceptibility to HIV infection? #### Summary points The majority of men who are HIV positive have been infected through the penis There is conclusive epidemiological evidence to show that uncircumcised men are at a much greater risk of becoming infected with HIV than circumcised men The inner surface of the foreskin contains Langerhans' cells with HIV receptors; these cells are likely to …

Stalkers and their Victims

Abstract: "Stalking" is defined as repeated and persistent unwanted communications and/or approaches that produce fear in the victim. The stalker may use such means as telephone calls, letters, e-mail, graffiti and placing notices in the media. A stalker may approach or follow the victim, or keep their residence under surveillance.

Voluntary Demand for Internal and External Auditing by Family Businesses

Abstract: This study investigates voluntary demand for auditing by family businesses, a significant but relatively unexplored segment of the economy. The paper considers demand for both internal and external auditing by using survey data to investigate the impact of firm characteristics linked to the cost vs. benefit of engaging an auditor. Variables examined are firm size, debt, and two agency proxies that measure separation of ownership and control, namely, the proportion of nonfamily management in the firm, and the proportion of nonfamily representation on the board of directors. The paper also considers the association between internal and external auditing. Descriptive results on voluntary demand for auditing by 186 family businesses revealed that internal audit was more prevalent than external audit, and outsourcing was a common method for providing internal audit. Results from logistic regression analyses provide support for the hypothesized impact of the two agency proxies and firm debt on demand for extern...

What is the purpose of this experiment? Or can students learn something from doing experiments?

Abstract: Historically there have been many claims made about the value of laboratory work in schools, yet research shows that it often achieves little meaningful learning by students. One reason, among many, for this failing is that students often do not know the ''purposes'' for these tasks. By purposes we mean the intentions the teacher has for the activity when she/he decides to use it with a particular class at a particular time. This we contrast with the ''aims'' of a laboratory activity, the often quite formalised statements about the intended endpoint of the activity that are too often the ''opening lines'' of a student laboratory report and are simply the ''expected'' specific science content knowledge outcomes—not necessarily learnt nor understood. This paper describes a unit of laboratory work which was unusual in that the teacher's purpose was to develop students' understanding about the way scientific facts are established with little expectation that they would understand the science content involved in the experiments. The unit was very successful from both a cognitive and affective perspective. An important feature was the way in which students gradually came to understand the teacher's purpose as they proceeded through the unit. fl 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 655 - 675, 2000 The research we report here focuses on the work of a highly informed and experienced science teacher (the first author) who sought to address her concerns about laboratory work. As we explain below, the study was a collaborative one in which the teacher and the researchers worked closely together as a research team, and the voices of both teacher and researchers are presented.

An Economy Driven Resource Management Architecture for Global Computational Power Grids

Abstract: The growing computational power requirements of grand challenge applications has promoted the need for linking highperformance computational resources distributed across multiple organisations. This is fueled by the availability of the Internet as a ubiquitous commodity communication media, low cost high-performance machines such as clusters across multiple organisations, and the rise of scientific problems of multi-organisational interest. The availability of expensive, special class of scientific instruments or devices and data sources in few organisations has increased the interest in offering a remote access to these resources. The recent popularity of coupling (local and remote) computational resources, special class of scientific instruments, and data sources across the Internet for solving problems has led to the emergence of a new platform called “Computational Grid”. This paper identifies the issues in resource management and scheduling driven by computational economy in the emerging grid computing context. They also apply to clusters of clusters environment (known as federated clusters or hyperclusters) formed by coupling multiple (geographically distributed) clusters located in the same or different organisations. We discuss our current work on the Nimrod/G resource broker, whose scheduling mechanism is driven by a user supplied application deadline and a resource access budget. However, current Grid access frameworks do not provide the dynamic resource trading services that are required to facilitate flexible application scheduling. In order to overcome this limitation, we have proposed an infrastructure called GRid Architecture for Computational Economy (GRACE). In this paper we present the motivations for grid computing, resource management architecture, Nimrod/G resource broker, computational economy, and GRACE infrastructure and its APIs along with future work.

Sex and site differences in cartilage development: A possible explanation for variations in knee osteoarthritis in later life

Abstract: OBJECTIVE: To test the hypothesis that sex-related and joint compartment-related differences in the risk of osteoarthritis (OA) of the knee might be associated with variations in cartilage development, we investigated knee cartilage volume in healthy children. METHODS: We studied 92 children who were randomly selected from among students in grades 3-12 of a single school in Hobart, Tasmania (49 boys, 43 girls; age range 9-18 years). Articular cartilage thickness and volume were determined at the patella, medial tibial compartment, and lateral tibial compartment by magnetic resonance imaging (MRI). Sagittal T1-weighted fat-suppressed MRI images were obtained and processed on an independent computer work station. RESULTS: Males had significantly more knee cartilage than females. Sex accounted for 6-36% of the variation in cartilage thickness and volume, which was statistically significant at all sites. Even after adjustment for age, body mass index, bone area, and physical activity, males had 16-31% higher cartilage volume; this was most marked at the medial tibial site. In addition, lateral tibial thickness was greater than medial tibial thickness (5.9 versus 3.6 mm; P < 0.0001) and lateral tibial volume was greater than medial tibial volume (2,823 versus 2,299 microl; P < 0.0001). Furthermore, physical activity was a significant explanatory factor for cartilage volume at all sites (R2 7-14% depending on site; all P < 0.05). The most consistent activity association was with vigorous activity in the previous 2 weeks (difference between any vigorous activity versus none 22-25% greater; all P < 0.05). CONCLUSION: Sex- and joint compartment-related differences in cartilage development may be one explanation for variations in the pattern of knee OA seen in later life. Furthermore, the physical activity associations suggest that cartilage development is amenable to modification.