Showing papers by "University of New South Wales published in 1987"

Task complexity as a moderator of goal effects: A meta-analysis.

Abstract: Much evidence exists that supports the use of goal setting as a motivational technique for enhancing task performance; howevei; little attention has been given to the role of task characteristics as potential moderating conditions of goal effects. Meta-analysis procedures were used to assess the moderator effects of task complexity for goal-setting studies conducted from 1966 to 1985 (n = 125). The reliability ofthe task complexity ratings was .92. Three sets of analyses were conducted: for goaldifficulty results (hard vs. easy), for goal specificity-difficulty (specific difficult goals vs. do-best or no goal), and for all studies collapsed across goal difficulty and goal specificity-difficulty. It was generally found that goal-setting effects were strongest for easy tasks (reaction time, brainstorming), d = .76, and weakest for more complex tasks (business game simulations, scientific and engineering work, faculty research productivity), d = .42. Implications for future research on goal setting and the validity of generalizing results are discussed.

High Efficiency Silicon Solar Cells

Abstract: Of all renewable energy technology, photovoltaics has possibly the most to gain from the development and commercialization of new ideas presently only in the conceptual or laboratory stage. Photovoltaics presently has a well established image of a high quality, high cost technology able to deliver in even the most demanding applications. However, there are no physical reasons why photovoltaics cannot retain the high quality performance features while being produced at the cost of not much more than glass sheet. This paper describes the work within the author's Centre directed at further improving performance features while reducing cost towards these lower limits. Further improvements in cell energy conversion efficiency have been achieved over the last year, as has on-going success in the commercialization of the Centre's buried contact cell technology. The paper also describes progress in the commercialization of the Centre's thin film multilayer cell technology in conjunction with Pacific Power via a newly incorporated company, Pacific Solar Pty. Ltd.

Strategy and structural adjustment to regain fit and performance: in defence of contingency theory

Abstract: Comparative, contingency approaches to organization structure have been criticized as being inherently static. The present article argues that functionalist theories and quantitative methods can explain structural change. This is exemplified by a diachronic enquiry into strategy and structure. Several propositions about organizational dynamics relating diversification, reorganization and performance are supported. However, the notion of contingency adjustment to structure to attain match as a frequent alternative to structural adjustment to contingencies is not borne out. Neither of the two prevailing theories of structural change, ‘contingency determinism’nor ‘strategic choice’, is completely adequate and a third formulation is advanced: that of ‘structural adjustment to regain fit’. While structural-functional enquiry into organizations using comparative quantitative methods has yielded information about structural statics, the contribution to knowledge of dynamics seems more problematic. This article seeks to record that structural-functionalism does inform the analysis of organizational change and to show that quantitative contingency approaches can illuminate change if the theory used in the analysis is formalized properly. This involves the partial abandonment of both of the main prevailing theories of structural change: contingency determinism and strategic choice. In their place this article offers as a potentially more fruitful model the structural adaptation to regain fit formulation. Within this the role of performance is shown to be important. The advantage of this framework is demonstrated empirically by means of an examination of the relationship between strategy and structure.

Efficient Vanadium Redox Flow Cell

Abstract: Excellent performance characteristics have been obtained with the all‐vanadium redox flow cell employing V(II)/V(III) and V(IV)/V(V) redox couples for the negative and positive half‐cells, respectively. Using 1.5M vanadium solutions in , carbon felt electrodes and a polystyrene sulfonic acid cation selective membrane, the cell was charged at 40 mA/cm2 and discharged across various loads. The coulombic efficiency was 90%, while the voltage efficiency calculated over the range 10–90% state‐of‐charge was 81%. An overall energy efficiency for the cell of 73% which, together with the simplicity of the system, makes the vanadium redox cell one of the promising energy storage systems currently under development.

Knowledge of motor commands and the recruitment of human motoneurons.

Abstract: This study examined the extent to which subjects can direct internal motor commands to specific pools of motoneurons. These commands were subthreshold for muscle activity and were presumably not associated with any change in background afferent activity. Percutaneous stimuli were delivered to the motor cortex using the technique of Merton and Morton (1980) while the discharge of the first-recruited motor units from two intrinsic hand muscles was recorded with selective needle electrodes. In the absence of movement or detectable electromyographic activity subjects learned to focus their internal command upon one of the pair of hand muscles such that a liminal cortical stimulus activated motoneurons in the ‘focused’ but not the ‘unfocused’ muscle. This ability was not acquired for pairs of muscles in the forearm. When the cortical stimuli activated only one motor unit in a muscle, the same unit was the first recruited during a voluntary contraction. These results suggest that motor commands can be precisely monitored and fractionated for individual intrinsic muscles of the human hand without recourse to afferent feedback. This ability may be useful for organizing and learning fine manipulative tasks.

Relationship between astrocytes, ganglion cells and vasculature of the retina.

Abstract: We have studied the distribution of astrocytes in the ganglion cell and nerve fibre layers of the retina in cat, rat, rabbit, and possum using anti-serum and a monoclonal antibody against glial fibrillary acidic protein (GFAP) and our own monoclonal antibody against glial filaments. The distribution of retinal astrocytes appears to be strongly determined by the vasculature of the retina; astrocytes are absent from almost all the retina of the possum and from the avascular regions of the rabbit retina. In the cat and rabbit, retinal astrocytes also show a strong affinity for the bundles of ganglion cell axons found at the inner surface of the retina. Retinal astrocytes do not invest the somas of ganglion cells, and even in areas of retina in which they are numerous, they are sharply confined to the layer of ganglion cell axons. It is suggested that retinal astrocytes are "immigrant" fibrous astrocytes that enter the retina with its vasculature.

Sport and the maintenance of masculine hegemony

Abstract: Sport is a crucial arena in which masculine hegemony is constructed and reconstructed. The effects of sporting activity are usefully analyzed in terms of two major dimensions. Those that relate directly to men, and those that serve dominant interests less directly, though no less effectively, through inferiorizing women and their activities. Processes through which sport directly supports male dominance are ones which associate males and maleness with valued skills and the sanctioned use of aggression/force/violence. Sport celebrates the dominant form of masculinity, though it must be noted that as well as women, some men are also excluded. This monopolization process is completed by a series of concrete processes which exclude women from the terrain completely, or if they do manage to pass through the barriers, effectively minimizes their achievements. Four concrete processes are considered and illustrated from the Australian sporting scene, those of definition, direct control, ignoring, and trivialization. It is necessary to understand these processes if we are to develop strategies to circumvent them. The mere fact that it is necessary for these processes to be continually invoked demonstrates that there are contradictions which can be exploited.

The Idea of Chinatown: The Power of Place and Institutional Practice in the Making of a Racial Category

Abstract: Racial categories are cultural ascriptions whose construction and transmission cannot be taken for granted. I focus here on the process by which racial categories are themselves constructed; in particular, I examine the presence of place and the role of state in the making of one such category, the “Chinese,” in a British settler society from the 1880s to the 1920s. I argue that “Chinatown,” like race, is an idea that belongs to the “white” European cultural tradition. The significance of government is that it has granted legitimacy to the ideas of Chinese and Chinatown, inscribing social definitions of identity and place in institutional practice and space. Indeed Chinatown has been a critical nexus through which the race definition process was structured. I examine this process in Vancouver, British Columbia, where the municipal authorities of the late nineteenth and early twentieth centuries sanctioned the intellectual milieu of race. They did this, I argue, as part of the historical exercise ...

The role of joint receptors in human kinaesthesia when intramuscular receptors cannot contribute.

Abstract: 1. Kinaesthetic acuity was tested at the distal interphalangeal joint of the middle finger when the hand was postured so that the joint was effectively disengaged from its muscular attachments. Subjects were required to detect the direction of 5 deg movements applied at different angular velocities from a mid-position under control conditions, after intra-articular injection of a plasma expander and after intra-articular injection of a local anaesthetic. 2. Kinaesthetic performance was enhanced after the injection of a plasma expander and deteriorated after injection of local anaesthetic. This deterioration could not be explained by spread of the local anaesthesic from the injection site on the dorsum of the joint. 3. The results suggest that the discharge of joint receptors can produce perceived signals of joint movement. Under normal conditions these receptors may duplicate the kinaesthetic input from muscle spindle endings.

Probabilistic and Evidential Approaches for Multisource Data Analysis

Abstract: Two methods for combining the information contents from multiple sources of remote-sensing image data and spatial data in general are described. One is a probabilistic scheme that employs a global membership function (similar to a joint posterior probability) that is derived from all available data sources. The other is an evidential calculus based upon Dempster's orthogonal sum combination rule. A feature of both methods is that uncertainty regarding data analysis can be incorporated into the process. Both schemes are evaluated in terms of their general applicability and certain equivalences are noted. Moreover, both are shown to perform well on mixed multispectral data.

After the Movies Transient Mood and Social Judgments

Abstract: The effects of transient moods on a variety of social judgments were studied in an unobtrusive field study. Subjects were interviewed immediately after leaving film performances classified as predominantly happy, sad, or aggressive in affective tone. Questions covered four topic areas: political judgments, expectations about the future, judgments of responsibility and guilt, and quality-of-life judgments. Judgments on all four question categories were significantly influenced by the affective quality of the films. Judgments were more positive, lenient or optimistic after viewing a happy film than after a sad or an aggressive film. These mood biases were universal irrespective of the demographic background of subjects, suggesting the robustness of the phenomenon. The results were interpreted in terms of recent models of emotional influences on social cognition, and the practical implications of the findings were considered.

L-Band Radar Backscatter Modeling of Forest Stands

Abstract: An L-band HH radar backscatter model of a coniferous forest stand is described and compared with SIR-B L-band image data of the Mount Shasta region of northern California. Being based upon an identification and implementation of the expected major components of forest backscattering, the model is simple in form and thus fast computationally, making possible extensive simulations of forest stands. A particularly important component in the model relates to representing the specular reflections expected from tree trunks to the ground and then back to the sensor. These are strong returns and are seen to be necessary to explain both the forest measurements made by the authors and the observations of others. Although the experimental data is limited in quantity and quality, agreement between available experimental and simulated values of forest backscatter is better than the residual uncertainty and relative calibration error of the experimental data, provided the model and experiment are matched initially at one set of parameter values.

An explanation of enhanced radar backscattering from flooded forests

Abstract: A simpie structural backscatter model for a forest stand, suitable for use with L-band HH polarized radar imagery, is used to explain the increased level of backscattering observed from flooded forests. Measurements made of relative levels of backscatter from SIR-B image data of a flooded Australian forest are consistent with an interpretation based upon scattering mechanisms involving both the tree components and the understorey or forest floor. The change in Fresnel power reflection coefficient of the ground with flooding is advanced as the cause of the enhancement in backscattered power levels.

Optimization of steam explosion as a method for increasing susceptibility of sugarcane bagasse to enzymatic saccharification.

Abstract: The technique of autohydrolysis steam explosion was examined as a means for pretreatment of sugarcane bagasse. Treatment conditions were optimized so that following enzymatic hydrolysis, pretreated bagasse would give 65.1 g sugars/100 g starting bagasse. Released sugars comprised 38.9 g glucose, 0.6 g cellobiose, 22.1 g xylose, and 3.5 g arabinose, and were equivalent to 83% of the anhydroglucan and 84% of the anhydroxylan content of untreated bagasse. Optimum conditions were treatment for 30 s with saturated steam at 220/sup 0/C with a water-to-solids ratio of 2 and the addition of 1 g H/sub 2/SO/sub 4//100 g dry bagasse. Bagasse treated in this manner was not inhibitory to fermentation by Saccharomyces uvarum except at low inoculum levels when fermentation time was extended by up to 24 h. Pretreated saccharified bagasse was inhibitory to Pachysolen tannophilus and this was attributed to the formation of acetate from the hydrolysis of acetyl groups present in the hemicullulose. The major advantage of the pretreatment is the achievement of high total sugar yield with moderate enzyme requirement and only minor losses due to sugar decomposition.

Species assembly and the evolution of community structure

Abstract: In this paper I consider the evolutionary and ecological implications of an assembly rule which was derived empirically from studies on a heathland small-mammal community in south-eastern Australia. This rule has been tested successfully against 52 heathland small-mammal assemblages. Here it is shown to hold also for 80 forest assemblages of small mammals spanning a latitudinal range from 27°S to 43°S in south-eastern Australia. The observed forest communities are predicted by the rule and they deviate significantly from random assemblages. I suggest that the unique evolutionary history of the Australian fauna has made these patterns more apparent. The rule is simply stated as: ‘There is a much higher probability that each species entering a community will be drawn from a different functional group (genus or other taxonomically related group of species with similar diets) until each group is represented, before the cycle repeats’. A theoretical basis for the rule is proposed which extends the niche compression hypothesis to cover evolutionary time. Evolutionary constraints on adaptations for diet selection are greater than those operating on habitat selection. Successful tests in North America for the granivorous desert rodent guild and the mixed-forest insectivore guild support a wider application of this rule than the Australian communities from which it was derived. A speculative model is proposed in which the mechanisms involved in the operation of this rule shape the evolution of community structure.

Topographic organization of the orientation column system in large flat-mounts of the cat visual cortex: a 2-deoxyglucose study.

Abstract: We developed a flat-mount technique in order to visualize, without additional reconstruction, the system of orientation columns in the cat visual cortex by using 2-deoxyglucose-autoradiography. Experimental animals were injected with 2-deoxyglucose and then stimulated for 45-60 minutes either with vertical or horizontal or oblique gratings alone or with vertical and horizontal gratings presented in alternation. In both areas 17 and 18 stimulation with either vertical or horizontal or oblique stripes produced similar and highly ordered patterns of parallel bands of increased 2-deoxyglucose uptake that were perpendicular to the boundaries of the areas. In area 17 they occasionally extended without interruption from the 17/18 border on the top of the lateral gyrus to the monocular segment in the splenial sulcus. Superposition of serial sections revealed that these bands were present in all cortical layers and in precise register along lines orthogonal to the lamination. The center-to-center spacing of the bands was 1.0-1.1 mm in area 17 and 1.2-1.4 mm in area 18. Stimulation with alternating vertical and horizontal contours led to a pattern the general organization of which resembled that induced by a single orientation but the spacing of which was reduced by a factor of 0.5. This strongly supports the concept that orientation is mapped in a system of parallel bands and argues against a recently formulated hypothesis that iso-orientation bands extend like spokes from centers that lack orientation selectivity (Braitenberg and Braitenberg, Biol. Cybern. 33:179-186, '79). Another characteristic feature, revealed by the flat-mount technique, was a periodic variation of 2-deoxyglucose uptake along the bands that gave them a beaded appearance. The mean center-to-center distance between adjacent beads on the same band was in the range of 0.9-1.2 mm and remained unchanged when horizontal and vertical gratings were presented in alternation. We propose that these beads reflect another columnar system whose features have yet to be determined.

Electromechanical stresses produced in the plasma membranes of suspended cells by applied electric fields.

Abstract: We analyze the electrical and mechanical stress in the bounding membrane of a cell (or vesicle) in suspension which is deformed by an external applied field. The membrane is treated as a thin, elastic, initially spherical, dielectric shell and the analysis is valid for frequencies less than the reciprocal of the charging time (i.e. less than MHz), or for constant fields. A complete analytic solution is obtained, and expressions are given which relate the deformation, the surface tension and the transmembrane potential difference to the applied field. We show that mechanical tensions in the range which lyse membranes are induced at values of the external field which are of the same order as those which are reported to lyse the plasma membranes of cells in suspension.

Lattice methods for multiple integration: theory, error analysis and examples

Abstract: This paper is concerned with numerical integration over the unit cube in s dimensions of functions that have reasonably smooth periodic extensions in each dimension. The concept of a lattice rule is introduced, and error bounds are developed in terms of the dual lattice. Examples of lattice rules discussed in the paper are the rectangle rule, the number-theoretic “good-lattice” methods of Korobov and others, the body-centred cubic rule, and a generalization of the latter to a family $\{ W_{nr} \} $. The $W_{nr} $ rules appear to have interesting extrapolation properties, both for fixed r and for $r = n$.