Showing papers by "University of Western Ontario published in 1992"
TL;DR: It is proposed that the ventral stream of projections from the striate cortex to the inferotemporal cortex plays the major role in the perceptual identification of objects, while the dorsal stream projecting from the stripping to the posterior parietal region mediates the required sensorimotor transformations for visually guided actions directed at such objects.
5,878 citations
01 Jan 1992
TL;DR: In this article, the authors present a model of the photosphere of the black body and its radiation, and the measurement of stellar continua, spectral lines, and photospheric pressure.
Abstract: 1. Background 2. Fourier transforms 3. Spectroscopic tools 4. Light detectors 5. Radiation terms and definitions 6. The black body and its radiation 7. Radiative and convective energy transport 8. The continuous absorption coefficient 9. The model photosphere 10. The measurement of stellar continua 11. The line absorption coefficient 12. The measurement of spectral lines 13. The behavior of spectral lines 14. The measurement of stellar radii and temperatures 15. The measurement of photospheric pressure 16. Chemical analysis 17. Velocity fields in stellar photospheres 18. Stellar rotation.
1,109 citations
802 citations
TL;DR: Only recently has the knowledge of the molecular and cellular events that occur in sepsis and its sequelae begun to shed light on the complex cascade of events underlying these disorders.
703 citations
15 Jun 1992
TL;DR: The performance of six optical flow techniques is compared, emphasizing measurement accuracy, and it is found that some form of confidence measure/threshold is crucial for all techniques in order to separate the inaccurate from the accurate.
Abstract: The performance of six optical flow techniques is compared, emphasizing measurement accuracy. The most accurate methods are found to be the local differential approaches, where nu is computed explicitly in terms of a locally constant or linear model. Techniques using global smoothness constraints appear to produce visually attractive flow fields, but in general seem to be accurate enough for qualitative use only and insufficient as precursors to the computations of egomotion and 3D structures. It is found that some form of confidence measure/threshold is crucial for all techniques in order to separate the inaccurate from the accurate. Drawbacks of the six techniques are discussed. >
697 citations
TL;DR: This article reviewed prior theory and empirical evidence relevant to the personality characteristics that differentiate charismatic leaders from noncharismatic leaders and concluded that the need for power, power inhibition, Machiavellianism, authoritarianism, narcissism, self esteem and locus of control are personality traits that are likely to differentiate personalized from socialized charismatic leaders.
Abstract: In this paper we review prior theory and empirical evidence relevant to the personality characteristics that differentiate charismatic leaders from noncharismatic leaders. We conclude from this review that charismatic leaders in present day complex organizations fit the stereotypical image of supportive, sensitive, nurturing, and considerate leaders such as Mahatma Gandhi or Nelson Mandela, rather than the traditional stereotype of aggressive, demanding, dominant and critical leaders such as Jim Jones or Field Marshall George Montgomery. We then present a review of research relevant to four traits that theoretically differentiate personalized (self-aggrandizing, non-egalitarian, and exploitive) charismatic leaders from socialized (collectively oriented, egalitarian, and nonexploitive) charismatic leaders. We conclude that the personality traits of the need for power, power inhibition, Machiavellianism, authoritarianism, narcissism, self esteem and locus of control are traits that are likely to differentiate personalized from socialized charismatic leaders.
693 citations
TL;DR: The scope and significance of the field of informetrics is defined and related to the earlier fields of bibliometrics and scientometrics; the phenomena studied by informetricians are identified.
Abstract: The scope and significance of the field of informetrics is defined and related to the earlier fields of bibliometrics and scientometrics. The phenomena studied by informetricians are identified. The major contributors to the field in the past are described and current emphases are related to the contributions in this Special Issue.
655 citations
TL;DR: In this paper, the authors focus on a paradox that emerges whenever one discusses leaders such as Robert Campeau, Max DePree, Lee Iacocca, Ross Johnson, Ralph Larsen, and Michael Milken: why are some charismatic leaders destructive, while others are beneficial to followers, organizations, and even entire societies?
Abstract: Executive Overview Charismatic business leaders are often heralded as corporate heroes by orchestrating turnarounds, launching new enterprises, engaging in organizational renewal or change, and obtaining extraordinary performance from individuals. The effectiveness of these leaders may be interpreted by executives as an unqualified recommendation for such leadership in their organizations. However the risks involved in charismatic leadership are at least as large as the promises. What is missing from current discussions about charisma is consideration of its darker side. In this article we focus on a paradox that emerges whenever one discusses leaders such as Robert Campeau, Max DePree, Lee Iacocca, Ross Johnson, Ralph Larsen, and Michael Milken: why are some charismatic leaders destructive, while others are beneficial to followers, organizations, and even entire societies? Drawing on the results from an interview study as well as the popular management literature, we describe the qualities and values tha...
581 citations
TL;DR: In this paper, the authors summarize the current theoretical and experimental understanding of clustering phenomena on surfaces, with an emphasis on dynamical properties, including surface diffusion coefficients and adatom binding energies.
559 citations
TL;DR: The authors developed a simple model that generates alternative market structures as Nash equilibria for different parameterizations of the basic model, such as a duopoly competing in exports or a single multinational producing in both markets.
547 citations
TL;DR: Work-family conflict was found to have a significant negative influence on an individual's quality of work life and quality of family life, which were highly related to life satisfaction.
TL;DR: During two recent canal occlusions, abundant “free‐floating particles” were identified within the posterior canal endolymph, which supports an alternate explanation to cupulolithiasis as the pathophysiological mechanism underlying BPPV.
Abstract: Most clinicians accept cupulolithiasis as the pathophysiological mechanism underlying benign paroxysmal positional vertigo (BPPV.) According to this theory, a cupular deposit induces a gravitational effect on the posterior canal crista. Posterior semicircular canal occlusion is a new operative procedure for treating incapacitating BPPV. It is postulated that canal occlusion abolishes endolymph movement within the canal, effectively fixing the cupula and rendering it unresponsive to both angular and linear acceleration (gravity). During two recent canal occlusions, abundant "free-floating particles" were identified within the posterior canal endolymph. When changing the position of the canal in the earth vertical plane, these free-floating particles would move under the influence of gravity. The hydrodynamic drag of the particles would induce endolymph movement with cupular displacement leading to the typical response. This finding supports an alternate explanation to cupulolithiasis as the pathophysiological mechanism underlying BPPV.
TL;DR: Despite differences among these animals in their histories of selection and the genetic backgrounds on which selection has acted, there is a common relationship between relative hippocampal size and spatial ability.
TL;DR: In this paper, the authors argue that there is inevitably a range of possible estimates for industrial output growth given the inherent index number and data problems, and that Hoppit and Berg and Hudson substantially overstate the industrial revolution.
Abstract: n the early i98os we published revised estimates of aggregate economic performance during the British industrial revolution which have stimulated reappraisal of the beginnings of modern economic growth.2 These new estimates have led most scholars to abandon the previous orthodoxy which had been based on the pioneering work of Deane and Cole.3 We have subsequently explored further aspects of the industrial revolution using our i982/3 estimates of the rate of growth as acceptable best guesses.4 Recently, however, several papers published in this journal have, with varying degrees of hostility, expressed doubts about our estimates.5 We think it is now opportune to respond to these comments. Our critics have questioned the appropriateness of our estimation techniques and have suggested that our overall view of the industrial revolution is misconceived. While we do not wish to dismiss the points that have been made, we feel both that many of the specific criticisms of our estimating techniques have been erroneous and that our overall view of the late eighteenth and early nineteenth centuries has been misunderstood. Initially in section I we present a brief summary of a coherent new view of British growth that emerged from our aggregate estimates. The bulk of the paper then takes up the technical issues that have recently been raised. In particular, we argue the following main points. First, that there is inevitably a range of possible estimates for industrial output growth given the inherent index number and data problems. Both Crafts's and Harley's original estimates fall within this range, as do Jackson's new estimates, whereas Deane and Cole's do not. Second, that we do not accept Jackson's case for preferring what he calls a Crafts rather than a Harley view of industrial output growth nor do we accept his dismissal of the indices of industrial output presented by Crafts, Leybourne, and Mills (CLM) and by Harley. Third, that Hoppit and Berg and Hudson substantially overstate
TL;DR: Eight patients with a homogeneous syndrome of progressive symmetric spinobulbar spasticity were studied and diagnostic criteria for primary lateral sclerosis based on clinical, laboratory and imaging features are proposed.
Abstract: Eight patients with a homogeneous syndrome of progressive symmetric spinobulbar spasticity were studied. Clinical features were limited to those associated with dysfunction of the descending motor tracts and included spastic quadriparesis, pseudobulbar affect, spastic dysarthria, hyper-reflexia and bilateral Babinski signs. Lower motor neuron findings were absent and higher cognitive function preserved. Median age of onset was 50.5 yrs and median disease duration was 19 yrs. Neuropathologic features (including morphometric analysis) in the single autopsied case confirmed the selective involvement of the motor cortex. There was complete absence of Betz cells from layer 5 of the precentral cortex and the remaining pyramidal cells were significantly smaller than those seen in normal controls. Magnetic resonance imaging (MRI) revealed atrophy of the precentral gyrus and positron emission tomography (PET) scans showed diminished glucose [18F]fluorodeoxyglucose uptake in the pericentral cortex. Magnetic motor cortex stimulation revealed markedly prolonged central motor conduction times. The literature is reviewed and diagnostic criteria for primary lateral sclerosis based on clinical, laboratory and imaging features are proposed.
TL;DR: This paper gives efficient polynomial-time algorithms for the case when one tree is a string or has a bounded number of leaves and shows that the problem is NP-complete even for binary trees having a label alphabet of size two.
TL;DR: The results indicate that TGF-beta produced at the human fetal-maternal interface plays a major regulatory role in the proliferation and differentiation of the trophoblast.
Abstract: We examined the localization of transforming growth factor (TGF)-beta in first-trimester and term human decidua and chorionic villi and explored the role of this factor on the proliferation and differentiation of cultured trophoblast cells. Two antibodies, 1D11.16.8, a mouse monoclonal neutralizing antibody capable of recognizing both TGF-beta 1 and TGF-beta 2 and CL-B1/29, a rabbit polyclonal antibody capable of recognizing TGF-beta 2, were used to immunolocalize TGF-beta in fixed, paraffin-embedded, or fixed, frozen sections of placenta and decidua, providing similar results. Intense labeling was observed in the extracellular matrix (ECM) of the first-trimester decidua and cytoplasm of term decidual cells. Syncytiotrophoblast cell cytoplasm as well as the ECM in the core of the chorionic villi of both first-trimester and term placentas exhibited a moderate degree of labeling. Strong cytoplasmic labeling was observed in the cytotrophoblastic shell of the term placenta. To examine the role of TGF-beta on trophoblast proliferation and differentiation, early passage cultures of first-trimester and primary cultures of term trophoblast cells were established and characterized on the basis of numerous immunocytochemical and functional markers. These cells expressed cytokeratin, placental alkaline phosphatase, urokinase-type plasminogen activator, and pregnancy-specific beta glycoprotein, but not factor VIII or 63D3; they also produced hCG and collagenase type IV. Exposure of first-trimester trophoblast cultures to TGF-beta 1 significantly inhibited proliferation in a dose-dependent manner. An antiproliferative effect was also noted in the presence of TGF-beta 2. These effects were abrogated in the presence of the neutralizing anti-TGF-beta antibody (1D11.16.8) in a concentration-dependent manner. In a 3-day culture, exogenous TGF-beta 1 stimulated formation of multinucleated cells by the first trimester as well as term trophoblast cells. Addition of neutralizing anti-TGF-beta antibody to first-trimester trophoblast cells stimulated proliferation beyond control levels in a 24-h culture and reduced formation of multinucleated cells in a 3-day culture, indicating the presence of endogenous TGF-beta activity. These results indicate that TGF-beta produced at the human fetal-maternal interface plays a major regulatory role in the proliferation and differentiation of the trophoblast.
TL;DR: The results indicate that lithium is not an important human teratogen and women with major affective disorders who wish to have children may continue lithium therapy, provided that adequate screening tests, including level II ultrasound and fetal echocardiography, are done.
TL;DR: In this paper, the shape of the attenuation curve of the Fourier spectrum of acceleration is established for southeastern Canada from empirical data, which includes 1200 digital vertical-component seismograms, from 100 earthquakes recorded on 30 stations of the Eastern Canada Telemetered Network.
Abstract: The shape of the attenuation curve of the Fourier spectrum of acceleration is established for southeastern Canada from empirical data. The dataset is comprised of 1200 digital vertical-component seismograms, from 100 earthquakes recorded on 30 stations of the Eastern Canada Telemetered Network. The distance range of the observations is 10 to 1700 km; focal depths are from 5 to 30 km.
Results indicate that the attenuation curve has three distinct sections. At distances less than 70 km, corresponding to attenuation of the direct wave, amplitudes decay slightly more rapidly than 1/ R ( R −1.1). Between 70 and 130 km, where the direct wave is joined by SmS , spectral amplitudes are approximately constant. Beyond 130 km, corresponding to the Lg phase, amplitudes decay at a rate that is consistent with R −0.5 and Q = 670 f 0.33. The findings support the hypothesis of Burger et al. (1987), that postcritical reflections from the Moho discontinuity play an important role in determining the shape of the attenuation curve. However, the influence of SmS is subtle, allowing the shape to be approximated by simple functional forms. For example, the commonly assumed bilinear form ( R −1, R −0.5, with frequency-dependent Q ) fits well if the transition from direct wave to Lg spreading is placed at approximately 60 km. A linear form ( R −1 over all distances, with constant Q = 2000) also provides a satisfactory fit overall. We find little evidence for the dependence of attenuation on focal depth or tectonic province.
TL;DR: Analysis of data from a self-administered survey of 306 high school students confirms a substantial gender difference in level of psychological distress and indicates that this gender difference may be due largely to higher levels of self-esteem among males and a tendency for adolescents to perceive their fathers to be overprotective.
Abstract: In this paper, we examine sources of gender differences in depressive symptoms among adolescents. Using data collected from a self-administered survey of 306 high school students, we examine differences in the impact of life events, psychosocial resources, and parent-child relationships on levels of psychological distress. Our results confirm a substantial gender difference in level of psychological distress. Moreover, analyses indicate that this gender difference may be due largely to higher levels of self-esteem among males and a tendency for adolescents to perceive their fathers to be overprotective. There is, however, also evidence that other psychosocial resources and parent-child relationships are implicated in this gender difference. We also present analyses to support our contention that parent-child relationships have important effects on the development of psychosocial resources of adolescents that, in turn, influence levels of depressive symptoms. Language: en
TL;DR: In this paper, a taxonomy of business-level strategies in global industries is presented, which includes four broad strategies: domestic product niche, exporting high quality offerings, international product innovation, and quasi-global combination.
Abstract: This study presents a taxonomy of business-level strategies in global industries. Empirical data suggest there are four broad strategies: domestic product niche, exporting high quality offerings, international product innovation, and quasi-global combination. A discussion of the characteristics and performance differentials of each strategy type is provided as well.
TL;DR: It is recommended that patients with malignant glioma be treated by parallel opposed fields with a margin that is 4 cm beyond the edge of the preoperative enhancing tumor, as seen on computerized tomography scan.
Abstract: Pre- and postoperative computerized tomography scans, simulator films, and computerized tomography scans documenting tumor recurrence were analyzed on 70 patients with supratentorial malignant glioma treated with whole brain plus boost radiation therapy to determine sites of recurrence in relation to the boost. The boost was planned using the postoperative computerized tomography scan. Tumor recurred in 53 patients--within the boost in 38 (72%), partly outside the boost in 12 (23%), outside the boost but within the brain in one (2%), in the boost and in the spinal cord in one (2%), and in the spinal cord only in one (2%). All recurrences confined to the brain were found within 4 cm of the enhancing tumor as defined by the preoperative computerized tomography scan. Recurrences outside the boost were more common with inadequate boost margins, small boost volumes, temporal lobe tumors, and homolateral wedge pair technique. Survival was not adversely affected by recurrence outside the boost. We recommend that patients with malignant glioma be treated by parallel opposed fields with a margin that is 4 cm beyond the edge of the preoperative enhancing tumor, as seen on computerized tomography scan.
TL;DR: It is shown how averaging repeated measurements changes the minimum detectable effect size between groups when both ME and sample size vary, and the pattern of character- specific measurement error is consistent across passerine species.
Abstract: We estimated measurement error (ME) associated with 15 skeletal characters in seven species of passerine birds. The total sample variance of the characters, from three mea? surements of each character on each individual, was partitioned into among- and within-indi? vidual components of variation. Measurement error, defined as that portion of the total sample variance made up by within-individual variation, ranged from 80%. Percent ME was inversely related to the size of a character, among-individual variation, and experience of the measurer. Other sources of ME included the character's flexibility and the definition of character landmarks. Although observer experience reduced ME, the effect was only substantial after more specimens were measured than are often used in morphometric studies. The magnitude of statistically detectable differences between groups was examined in relation to the level of ME and the sample sizes of groups. Measurement error increased the chances of finding no group difference, i.e., making type II errors. Type II errors can be reduced either by averaging two or more repeated measurements of the same individual, thereby reducing ME, or by increasing the sample size. We show how averaging repeated measurements changes the minimum detectable effect size between groups when both ME and sample size vary. The pattern of character- specific measurement error is consistent across passerine species; both reliable and unreliable characters for morphometric studies are identified. (Measurement error; morphometrics; type II error; passerines; model II ANO VA; statistical power.)
TL;DR: It is concluded that the EEG is a sensitive index of brain function in septic encephalopathy and that it is especially useful in the intensive care monitoring of patients with sepsis.
Abstract: To define the EEG and associated clinical features of septic encephalopathy, we studied 62 patients with positive blood cultures. Patients were divided into three clinical groups: nonencephalopathic (NE), mildly encephalopathic (ME), and severely encephalopathic (SE); the latter two groups had diffuse cerebral dysfunction. EEGs were classified into five groups: normal, excessive theta, predominant delta, triphasic waves, and suppression or burst suppression, in ascending order of severity. The EEG (1) was more sensitive than our clinical criteria for encephalopathy, (2) showed features that were, when considered with clinical and laboratory characteristics, compatible with a potentially reversible encephalopathy, and (3) had well-defined categories that correlated with percent mortality, even within a single clinical group. We conclude that the EEG is a sensitive index of brain function in septic encephalopathy and that it is especially useful in the intensive care monitoring of patients with sepsis.
TL;DR: In comparison with existing steam sterilization technology, this new method of sterilization using relatively low temperature and short treatment time could prove to be an excellent method to minimize thermal denaturation of important nutrient components in liquid media.
Abstract: The technique of irreversible electroporation has been successfully applied to cause a lethal effect on Lactobacillus brevis cells suspended in phosphate buffer solution, Na(2)HPO(4)/NaH(2)PO(4) . H(2)O (0.845/0.186 mM) between parallel plane electrodes. Tests were carried out at different temperatures (24,45,60, and 80 degrees C) to determine if there was a synergistic effect of temperature and electric pulse treatment on the destruction of L. brevis. Experimental results indicate that the viability (log N/N(0); where N(0) and N are the number of cells survived per milliliter before and after pulse voltage application, respectively) of L. brevis decreased with electric field strength E and temperature T and treatment time t(t). The relations between log(N/N(0)) and t(t) and log(N/N(0)) and E indicate that higher field strengths are more effective than higher treatment times in causing destruction of L. brevis cells. It was also found that as the temperature of the liquid medium containing L. brevis cells increased from 24 to 60 degrees C, the death rate of L. brevis cells increased with a decrease in the total treatment time t(t) (pulse width x number of pulses applied). The application of an electric field strength E = 25 kV/cm at 60 degrees C and treatment time t(t) = 10 ms resulted in very high destruction levels of L. brevis cells (N/N(0) = 10(-9)). In comparison with existing steam sterilization technology, this new method of sterilization using relatively low temperature and short treatment time could prove to be an excellent method to minimize thermal denaturation of important nutrient components in liquid media.
TL;DR: Trophoblast cells of the placenta in many species have acquired mechanisms to invade the uterus, inclusive of its blood vessels, to establish efficient fetomaternal exchange of molecules, and TGF-beta provides the key control of trophoblast invasiveness in situ.
Abstract: Trophoblast cells of the placenta in many species have acquired mechanisms to invade the uterus, inclusive of its blood vessels, to establish efficient fetomaternal exchange of molecules. This invasion is strictly controlled both spatially and temporally and, in humans, usually continues until midgestation. Key mechanisms underlying various steps in trophoblast invasion are: (i) the attachment to the basement membrane, most likely by binding to laminin; (ii) the detachment from the basement membrane matrix, a process requiring the presence of complex-type oligosaccharides on the cell surface; and (iii) the breakdown of basement membrane components, mediated by secretion of metalloproteases (such as type IV collagenases) and serine proteases (plasminogen activator). Activation of trophoblast-derived metalloproteases appears to be plasmin dependent. Trophoblast invasiveness in situ is controlled by the microenvironment, owing to local production of anti-invasive factors by the decidual tissue of the uterus. One of these factors is TIMP (tissue inhibitor of metalloproteases), which neutralizes metalloproteases in an equimolar ratio. Another is TGF-beta (transforming growth factor-beta), which has a dual effect: it induces TIMP-1 secretion by the trophoblast and decidual cells and promotes differentiation of invasive trophoblast cells into multinucleated giant cells, which are presumably noninvasive. Thus, TGF-beta provides the key control of trophoblast invasiveness in situ. This control is lost in certain choriocarcinomas. In contrast to the response shown by the normal trophoblast, JAR and JEG-3 choriocarcinoma cell invasiveness does not seem to be inhibited by TGF-beta. In fact, in preliminary studies, JAR cells responded to TGF-beta by increased invasiveness.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: This paper examined differences in the antecedents and consequences of work-family conflict, a form of interrole conflict that occurs when the demands of work and family are mutually incompatible in some respect.
Abstract: This research examines differences in the antecedents and consequences of work—family conflict — a form of interrole conflict that occurs when the demands of work and family are mutually incompatible in some respect — for two groups of career‐oriented men: those with a homemaker wife (called traditional‐career men) and those with a spouse in a career‐oriented job (labelled dual‐career men). Using a model built on the work of Kopelman, Greenhaus and Connolly (1983), the responses from 136 dual‐career men and 137 traditional‐career men were compared. The primary conclusion of this research is that maternal career employment has a significant effect on the antecedents of work — family conflict. Dual‐career men appear to experience a significant negative spillover from their work domain. We suggest that this spillover is due to a lack of structural flexibility in the workplace, outdated organizational policies that operate on the myth of separate worlds' and a lack of social support for the male dual‐career role which contradicts societal norms. Copyright
TL;DR: This survey presents the basic notions and concepts of adaptive sorting, the demonstration that several algorithms currently in use are adaptive, and the development of new algorithms, similar to currently used algorithms that perform competitively on random sequences and are significantly faster on nearly sorted sequences.
Abstract: The design and analysis of adaptive sorting algorithms has made important contributions to both theory and practice. The main contributions from the theoretical point of view are: the description of the complexity of a sorting algorithm not only in terms of the size of a problem instance but also in terms of the disorder of the given problem instance; the establishment of new relationships among measures of disorder; the introduction of new sorting algorithms that take advantage of the existing order in the input sequence; and, the proofs that several of the new sorting algorithms achieve maximal (optimal) adaptivity with respect to several measures of disorder. The main contributions from the practical point of view are: the demonstration that several algorithms currently in use are adaptive; and, the development of new algorithms, similar to currently used algorithms that perform competitively on random sequences and are significantly faster on nearly sorted sequences. In this survey, we present the basic notions and concepts of adaptive sorting and the state of the art of adaptive sorting algorithms.
TL;DR: This study provides the first clear kinematic evidence that binocular vision (stereopsis and possibly vergence) makes a significant contribution to the accurate programming of prehensile movements in humans.
TL;DR: White-matter changes are common, vascular risk factors are treatable, strokes are preventable, so the vascular dementias need to be addressed because the solutions matter, and preventable senility is preventable.