Showing papers by "University of New South Wales published in 1991"

Stewardship Theory or Agency Theory: CEO Governance and Shareholder Returns:

Abstract: Agency theory argues that shareholder interests require protection by separation of incumbency of roles of board chair and CEO. Stewardship theory argues shareholder interests are maximised by shared incumbency of these roles. Results of an empirical test fail to support agency theory and provide some support for stewardship theory.

Postural stability and associated physiological factors in a population of aged persons

Abstract: A battery of 13 visual, vestibular, sensorimotor, and balance tests was administered to 95 elderly persons (mean age 82.7 years) to examine the relationships between specific sensorimotor functions and measures of postural stability. When subjects stood on a firm surface, increased body sway was associated with poor tactile sensitivity and poor joint position sense. When subjects stood on a compliant surface (which reduced peripheral sensation) with their eyes open, increased body sway was associated with poor visual acuity and contrast sensitivity, reduced vibration sense, and decreased ankle dorsiflexion strength as well as reduced joint position sense. Increased body sway with eyes closed on the compliant surface was associated with poor tactile sensation, reduced quadriceps and ankle dorsiflexion strength, and increased reaction time. Poor performance in two clinical measures of postural stability was associated with reduced sensation in the lower limbs as measured by joint position sense, tactile sensitivity and vibration sense, reduced quadriceps and ankle dorsiflexion strength, and slow reaction times. The prevalence of vestibular impairments was high in this group, but vestibular function was not significantly associated with sway under any of the test conditions. The results suggest that reduced sensation, muscle weakness in the legs, and increased reaction time are all important factors associated with postural instability. An analysis of the percentage increases in sway under conditions where visual and peripheral sensation systems are removed or diminished, compared with sway under optimal conditions, indicated that peripheral sensation is the most important sensory system in the maintenance of static postural stability.

Development and Testing of a Model of Consideration Set Composition

Abstract: The authors develop a model of consideration set composition. The approach taken is to compare the marginal expected benefits of including an additional brand in the consideration set with its asso...

Liquid junction potentials and small cell effects in patch-clamp analysis.

Abstract: Since the early 1980s, the patch-clamp technique (Hamill et al., 1981) has been of particular value in investigating the properties of ion channels in cells. When used in either the intact or excised configurations, the properties of individual ionic channels can be directly measured. In addition, the whole-cell configuration can be used to investigate the total response of the full complement of channels in a cell. The whole-cell configuration is of particular value in exploring the properties of very small cells which are not readily accessible to conventional microelectrode techniques. in all of the above measurements, there are two potential sources of error, in every situation there may be significant errors due to uncompensated junction potentials, which m a y a p p e a r to be eliminated by the normal zeroing procedure whereby residual potentials between pipette and bath solutions are offset prior to patch formation. In addition, in the intact and whole-cell patch configurations, the effect of the cells being small can introduce radical errors in the measurement of single-channel and whole-cell properties. The aim of this review is firstly to outline the contribution of such junction potentials and the errors resulting from measurements on small cells and secondly to indicate how adequate junction potential corrections can be applied and the true values of underlying membrane parameters determined for such cells. Where necessary, appropriate equations have been presented. Much of the material is a review of published work. However, the review also seeks to extend the implications of that work and, in particular, it also includes (in an appendix) a timedependent solution of the current relaxation following a channel closure.

Physiological factors associated with falls in an elderly population.

Abstract: OBJECTIVE: To determine whether a battery of 13 sensorimotor, vestibular, and visual tests discriminates between elderly fallers and elderly non-fallers. DESIGN: One-year prospective study. SETTING: Conducted at a 124-bed Hostel for Aged Persons, in Sydney, Australia. PARTICIPANTS: Ninety-five persons aged between 59 and 97 years (mean age 82.7 years) took part in the study. Of the 29 non-participants, four were ill, five were absent (on holidays, etc), and 20 declined. Residents were generally independent in activities of daily living although personal care assistance was available. RESULTS: Eighty-four participants were available for follow-up. In the follow-up year, 40 subjects experienced no falls, 11 subjects fell one time only, 33 residents fell on two or more occasions. There was a total of 145 falls. Discriminant function analysis identified proprioception in the lower limbs visual contrast sensitivity, ankle dorsiflexion strength, reaction time, and sway with the eyes closed as the variables that significantly discriminated between subjects who experienced multiple falls and subjects who experienced no falls or one fall only. This procedure correctly classified 79% of subjects into multiple faller or non-multiple faller groups. Quadriceps strength was poorer in the multiple fallers compared with the non-fallers and once-only fallers, although the difference was not statistically significant. There was little difference in the mean scores for the tests of vestibular function in the non-fallers, once-only fallers, and multiple fallers. CONCLUSION: It appears that this approach highlights some key physiological factors that predispose elderly individuals to falls. Language: en

Immunology and clinical importance of antiphospholipid antibodies.

Abstract: Having reviewed the literature on the association of aPL antibodies with clinical manifestations, it is clear that this group of autoantibodies are of considerable importance. The presence of aPL antibodies in some but not all individuals confers a risk of a clinical syndrome characterized by recurrent arterial or venous thrombosis, thrombocytopenia, hemolytic anemia, or positive Coombs' test, and in females, recurrent idiopathic fetal loss. In SLE, the risk is approximately 40%, compared with a risk of 15% in the absence of aPL antibodies. However, only one half of persons possessing these antibodies have SLE, and overall the risk is around 30%. In some circumstances, such as in chlorpromazine or infection-associated aPL antibodies, there appears to be no increased risk. At the other end of the spectrum are seen patients whose only clinical manifestations comprise features of this clinical syndrome, and this entity has been designated the primary antiphospholipid syndrome (PAPS). aPL antibodies are also important because they are not uncommon. They have been found frequently in women with idiopathic recurrent fetal loss (30%), in non-autoimmune patients with ischemic heart disease (20%), or venous thrombosis (up to 30%), or stroke (4-47%), and in chronic immune thrombocytopenia (30%). These autoantibodies can be detected using sensitive solid-phase immunoassays employing the CL antigen, or in appropriate coagulation tests to detect LA activity. These assays are simple to perform but require care in selection of the best test and in interpretation of results. Current tests do not distinguish between those persons at risk of the clinical events and those not at risk. Detection of specific isotypes (especially IgG) and antibody level may aid in such a designation. Treatment of aPL antibody-associated syndromes remains a controversial subject. Since thromboses are associated with significant morbidity and potential mortality, there is a good argument for long-term preventive antithrombotic therapy, at least for as long as the antibodies are detectable, in those patients in whom clinical complications have previously occurred. It is not generally recommended that this treatment be offered to individuals in whom aPL antibodies are detected but who have not suffered previous thromboses, since the risk of such events does not appear to be equal within a group of aPL antibody-positive persons. This particularly applies to pregnant women, since live births and uncomplicated pregnancies are observed regularly in the presence of aPL antibodies without specific treatment. A previous history of at least one unexplained, late fetal loss is considered a prerequisite before intervention in subsequent pregnancies.(ABSTRACT TRUNCATED AT 400 WORDS)

Regression with frailty in survival analysis.

Abstract: In studies of survival, the hazard function for each individual may depend on observed risk variables but usually not all such variables are known or measurable. This unknown factor of the hazard function is usually termed the individual heterogeneity or frailty. When survival is time to the occurrence of a particular type of event and more than one such time may be obtained for each individual, frailty is a common factor among such recurrence times. A model including frailty is fitted to such repeated measures of recurrence times.

Evidence for Cognitive Load Theory

Abstract: Dixon (1991) and Goldman (1991) have provided thoughtful commentaries on Chandler and Sweller (1991). The general issue they raise concerns the scientific procedures we should use when conducting research in cognition and instruction. It is an issue of great importance, and we welcome the opportunity provided by their criticisms to discuss the techniques we use. To clarify the findings based on cognitive load theory, we begin by indicating the essential characteristics of a theory concerned with cognition and instruction, followed by a brief history of cognitive load theory to make clear that it has these characteristics. These statements will then be used to address specific comments made by Goldman and Dixon.

Optimized antireflection coatings for high-efficiency silicon solar cells

Abstract: Antireflection coatings for silicon solar cells have been optimized both theoretically and experimentally for a range of possible situations, such as single-layer and double-layer coatings, and on planar and microgrooved surfaces. The effect of a thin passivating silicon dioxide layer under the coating was also considered. A critical passivating oxide thickness of about 300 AA was found to be important for the design of these coatings. A new half-quarter-wavelength double layer antireflection coating can be achieved with very low reflection if the passivating oxide has to be thicker than this critical thickness. >

Equity, Equality, Power, and Conflict

Abstract: Although equity theory has dominated the conception of justice in organizational relations, equality also shapes justice expectations and behaviors. Therefore, there are two basic and, in principle, inevitable pressures toward conflict: (a) one stems from equity violations and results in overt conflict involving attempts to restore justice and (b) the other stems from equality violations and results in nondirected conflict that is symptomatic of decreased social cohesiveness. Power shapes distributive orientations, and, therefore, it is an important determinant of conflict pressures. A framework linking distributive justice principles, power, and conflict is advanced and used to suggest a new perspective on issues of organizational strategy.

An atlas of mid-infrared spectra of galaxy nuclei

Abstract: The spectral energy distributions are presented for 60 galaxies for which 8-13 μm, and in some cases 17-23 μm, spectra have been obtained. These IR bright galaxies are discussed in terms of their spectral properties in the mid-IR and the relationship with their far-IR properties. Almost all of the galaxies can be placed in one of three classes on the basis of their 8-13 μm spectra : those dominated by the family of narrow bands between 3-13 μm, those with featureless continua and those that display the silicate absorption band. H II region galaxy nuclei, i.e., those which contain powerful nuclear H II regions and whose mid-IR spectra are dominated by emission in the family of narrow emission bands display little dispersion in their IR properties.

On optimal data-based bandwidth selection in kernel density estimation

Abstract: A bandwidth selection method is proposed for kernel density estimation. This is based on the straightforward idea of plugging estimates into the usual asymptotic representation for the optimal bandwidth, but with two important modifications. The result is a bandwidth selector with the, by nonparametric standards, extremely fast asymptotic rate of convergence of n−½ where n → ∞ denotes sample size. Comparison is given to other bandwidth selection methods, and small sample impact is investigated.

Visual acuity and contrast sensitivity in relation to falls in an elderly population

Abstract: Visual acuity and contrast sensitivity were measured in 95 residents of a hostel for the aged (mean age = 83 years) using a dual-contrast letter chart and the Melbourne Edge Test (MET). Vision (as measured by visual acuity, the MET, low-contrast visual acuity, and difference between high- and low-contrast acuity) decreased significantly with age and all four measures were significantly correlated. Subjects with a clinical eye disorder had poorer vision than those without a disorder although the differences were not significant. Visual acuity and contrast sensitivity were not associated with body sway when subjects were standing on a firm base. However, when the subjects were placed in a situation which provided reduced support (standing on a compliant surface), body sway was associated with poor visual acuity and contrast sensitivity. There was also a difference in contrast sensitivity between those who fell one or more times in a year of follow-up and those who did not fall. It appears that reduced vision may be a predisposing factor to postural imbalance and falls in elderly persons.

Role of CD11/CD18 in shear rate-dependent leukocyte-endothelial cell interactions in cat mesenteric venules.

Abstract: In vivo microscopy was used to assess the relationships among shear rate (and shear stress), leukocyte rolling velocity, and leukocyte adherence in a cat mesentery preparation. Shear rate in individual venules and arterioles of 25-35 microns diameter were varied over a wide range by graded occlusion of an arterial loop. There was a linear decline in leukocyte rolling velocity (Vwbc) as red cell velocity (Vrbc) was reduced. The ratio Vwbc/Vrbc remained constant despite variations in shear stress from 5-25 dyn/cm2. A reduction in shear stress was associated with an increased leukocyte adherence, particularly when Vwbc was reduced below 50 microns/s. Reduction in wall shear rate below 500 s-1 in arterioles allowed 1-3 leukocytes to adhere per 100 microns length of vessel, while venules exposed to the same shear rates had 5-16 adherent leukocytes. In arterioles, leukocyte rolling was only observed at low shear rates. At shear rates less than 250 s-1 leukocyte rolling velocity was faster in arterioles than venules, and the ratio Vwbc/Vrbc for arterioles was 0.08 +/- 0.02, which was fourfold higher than the ratio obtained in venules at similar shear rates. Pretreatment with the CD18-specific antibody (mAb) IB4 increased leukocyte rolling velocity in venules by approximately 20 microns/s at red cell velocities below 2,000 microns/s. mAb IB4 largely prevented the leukocyte adherence to arterioles and venules, and increased the ratio Vwbc/Vrbc observed in venules at low shear elicit a CD18-dependent adhesive interaction between leukocytes and microvascular endothelium, and that differences in shear rates cannot explain the greater propensity for leukocyte rolling and adhesion in venules than arterioles.

Lysozyme and alpha-lactalbumin: structure, function, and interrelationships.

Abstract: Publisher Summary This chapter considers both the structure and function of α-lactalbumin and lysozyme in relation to each other, and also the potential significance of the studies in health and the pathology of disease, such as cancer. The chapter begins with brief report of the early discovery of the occurrence and isolation of these proteins and the elucidation of their function and homology, followed by a brief discussion of some problems in their isolation and the determination of their activity. Various aspects of their three-dimensional structures and their significance are also considered. Studies on the implications of their sequence similarities are summarized and also on the binding of metal ions, especially calcium (II), and consider their implications. A brief discussion of lactose synthase, an enzyme of which a-lactalbumin and galactosyltransferase are essential components, is provided. The determination of the three-dimensional structure of domestic hen egg-white lysozyme was the first elucidation of the X-ray crystal structure of an enzyme. Attention was directed to models for the α-lactalbumin structure based on the coordinates for lysozyme and on energy minimization programs.

The dopamine theory of attention deficit hyperactivity disorder (adhd)

Abstract: Clinical, animal and neuroanatomical studies of differential isomer and dosage effects of CNS stimulant medications on behaviour are reviewed. Wender's hypothesis that an underlying biochemical abnormality and a disorder of reinforcement was the primary deficit in "MBD" children is restated in terms of a disorder of polysynaptic dopaminergic circuits, between prefrontal and striate centres. Wender's notion of a disorder of reinforcement is broadened to include a disorder of planning and correction of behaviour, including capacity for cortical control of automatic instinctual motor programmes. The dopamine hypothesis of Attention Deficit Hyperactivity Disorder (ADHD) is examined from the point of view of differential dose effects of CNS stimulant medications, and theories of neural control. Clinical, animal and neuropharmacological studies are reviewed. Implications of the findings for understanding clinical and side effects in ADHD children of stimulants are discussed.