Showing papers by "University of Waterloo published in 2002"

Initial sequencing and comparative analysis of the mouse genome.

Abstract: The sequence of the mouse genome is a key informational tool for understanding the contents of the human genome and a key experimental tool for biomedical research. Here, we report the results of an international collaboration to produce a high-quality draft sequence of the mouse genome. We also present an initial comparative analysis of the mouse and human genomes, describing some of the insights that can be gleaned from the two sequences. We discuss topics including the analysis of the evolutionary forces shaping the size, structure and sequence of the genomes; the conservation of large-scale synteny across most of the genomes; the much lower extent of sequence orthology covering less than half of the genomes; the proportions of the genomes under selection; the number of protein-coding genes; the expansion of gene families related to reproduction and immunity; the evolution of proteins; and the identification of intraspecies polymorphism.

Role of Pseudomonas putida Indoleacetic Acid in Development of the Host Plant Root System

Abstract: Many plant-associated bacteria synthesize the phytohormone indoleacetic acid (IAA). While IAA produced by phytopathogenic bacteria, mainly by the indoleacetamide pathway, has been implicated in the induction of plant tumors, it is not clear whether IAA synthesized by beneficial bacteria, usually via the indolepyruvic acid pathway, is involved in plant growth promotion. To determine whether bacterial IAA enhances root development in host plants, the ipdc gene that encodes indolepyruvate decarboxylase, a key enzyme in the indolepyruvic acid pathway, was isolated from the plant growth-promoting bacterium Pseudomonas putida GR12-2 and an IAA-deficient mutant constructed by insertional mutagenesis. The canola seedling primary roots from seeds treated with wild-type P. putida GR12-2 were on average 35 to 50% longer than the roots from seeds treated with the IAA-deficient mutant and the roots from uninoculated seeds. In addition, exposing mung bean cuttings to high levels of IAA by soaking them in a suspension of the wild-type strain stimulated the formation of many, very small, adventitious roots. Formation of fewer roots was stimulated by treatment with the IAA-deficient mutant. These results suggest that bacterial IAA plays a major role in the development of the host plant root system.

The Comparative RNA Web (CRW) Site: an online database of comparative sequence and structure information for ribosomal, intron, and other RNAs

Abstract: Background: Comparative analysis of RNA sequences is the basis for the detailed and accurate predictions of RNA structure and the determination of phylogenetic relationships for organisms that span the entire phylogenetic tree. Underlying these accomplishments are very large, wellorganized, and processed collections of RNA sequences. This data, starting with the sequences organized into a database management system and aligned to reveal their higher-order structure, and patterns of conservation and variation for organisms that span the phylogenetic tree, has been collected and analyzed. This type of information can be fundamental for and have an influence on the study of phylogenetic relationships, RNA structure, and the melding of these two fields. Results: We have prepared a large web site that disseminates our comparative sequence and structure models and data. The four major types of comparative information and systems available for the three ribosomal RNAs (5S, 16S, and 23S rRNA), transfer RNA (tRNA), and two of the catalytic intron RNAs (group I and group II) are: (1) Current Comparative Structure Models; (2) Nucleotide Frequency and Conservation Information; (3) Sequence and Structure Data; and (4) Data Access Systems. Conclusions: This online RNA sequence and structure information, the result of extensive analysis, interpretation, data collection, and computer program and web development, is accessible at our Comparative RNA Web (CRW) Site [http://www.rna.icmb.utexas.edu] . In the future, more data and information will be added to these existing categories, new categories will be developed, and additional RNAs will be studied and presented at the CRW Site.

Adaptive optics scanning laser ophthalmoscopy

Abstract: We present the first scanning laser ophthalmoscope that uses adaptive optics to measure and correct the high order aberrations of the human eye. Adaptive optics increases both lateral and axial resolution, permitting axial sectioning of retinal tissue in vivo. The instrument is used to visualize photoreceptors, nerve fibers and flow of white blood cells in retinal capillaries.

Examining the link between knowledge management practices and types of innovation

Abstract: The management of knowledge is frequently identified as an important antecedent of innovation. However, very little empirical research has specifically addressed antecedents and consequences of effective knowledge management. Using data collected from 443 New Zealand firms, a knowledge management instrument, which comprises three components and 16 factors, is regressed against a three‐factor innovation scale that captures incremental innovation, innovation that changes consumers’ behaviour and innovation that destroys existing competencies. The results of this research show that knowledge acquisition and responsiveness to knowledge are more important for innovation than knowledge dissemination.

The biotic ligand model : a historical overview

Abstract: During recent years, the biotic ligand model (BLM) has been proposed as a tool to evaluate quantitatively the manner in which water chemistry affects the speciation and biological availability of metals in aquatic systems. This is an important consideration because it is the bioavailability and bioreactivity of metals that control their potential to cause adverse effects. The BLM approach has gained widespread interest amongst the scientific, regulated and regulatory communities because of its potential for use in developing water quality criteria (WQC) and in performing aquatic risk assessments for metals. Specifically, the BLM does this in a way that considers the important influences of site-specific water quality. This journal issue includes papers that describe recent advances with regard to the development of the BLM approach. Here, the current status of the BLM development effort is described in the context of the longer-term history of advances in the understanding of metal interactions in the environment upon which the BLM is based. Early developments in the aquatic chemistry of metals, the physiology of aquatic organisms and aquatic toxicology are reviewed first, and the degree to which each of these disciplines influenced the development of water quality regulations is discussed. The early scientific advances that took place in each of these fields were not well coordinated, making it difficult for regulatory authorities to take full advantage of the potential utility of what had been learned. However, this has now changed, with the BLM serving as a useful interface amongst these scientific disciplines, and within the regulatory arena as well. The more recent events that have led to the present situation are reviewed, and consideration is given to some of the future needs and developments related to the BLM that are envisioned. The research results that are described in the papers found in this journal issue represent a distinct milestone in the ongoing evolution of the BLM approach and, more generally, of approaches to performing ecological assessments for metals in aquatic systems. These papers also establish a benchmark to which future scientific and regulatory developments can be compared. Finally, they demonstrate the importance and usefulness of the concept of bioavailability and of evaluative tools such as the BLM.

A survey of user-centered design practice

Abstract: This paper reports the results of a recent survey of user-centered design (UCD) practitioners. The survey involved over a hundred respondents who were CHI'2000 attendees or current UPA members. The paper identifies the most widely used methods and processes, the key factors that predict success, and the critical tradeoffs practitioners must make in applying UCD methods and processes. Results show that cost-benefit tradeoffs are a key consideration in the adoption of UCD methods. Measures of UCD effectiveness are lacking and rarely applied. There is also a major discrepancy between the commonly cited measures and the actually applied ones. These results have implications for the introduction, deployment, and execution of UCD projects

Hybrid TDOA/AOA mobile user location for wideband CDMA cellular systems

Abstract: This paper proposes a mobile user location scheme for wideband code-division multiple-access (CDMA) wireless communication systems. To achieve high location accuracy and low cost of the mobile receiver, the location scheme combines the time difference of arrival (TDOA) measurements from the forward link pilot signals with the angle of arrival (AOA) measurement from the reverse link pilot signal. High chip rates in wideband CDMA systems facilitate accurate TDOA measurements, and a smart antenna used at the home base station (BS) can provide accurate AOA measurement in a macrocell environment. A two-step least square location estimator is developed based on a linear form of the AOA equation in the small error region. Numerical results demonstrate that the proposed hybrid TDOA/AOA location scheme gives a much higher location accuracy than TDOA only location, when the number of base stations is small and/or when the TDOA measurements have a relatively poor accuracy.

Root Endodermis and Exodermis: Structure, Function, and Responses to the Environment

Abstract: Roots of virtually all vascular plants have an endodermis with a Casparian band, and the majority of angiosperm roots tested also have an exodermis with a Casparian band. Both the endodermis and exodermis may develop suberin lamellae and thick, tertiary walls. Each of these wall modifications has its own function(s). The endodermal Casparian band prevents the unimpeded movement of apoplastic substances into the stele and also prevents the backflow of ions that have moved into the stele symplastically and then were released into its apoplast. In roots with a mature exodermis, the barrier to apoplastic inflow of ions occurs near the root surface, but prevention of backflow of ions from the stele remains a function of the endodermis. The suberin lamellae protect against pathogen invasion and possibly root drying during times of stress. Tertiary walls of the endodermis and exodermis are believed to function in mechanical support of the root, but this idea remains to be tested. During stress, root growth rates decline, and the endodermis and exodermis develop closer to the root tip. In two cases, stress is known to induce the formation of an exodermis, and in several other cases to accelerate the development of both the exodermis and endodermis. The responses of the endodermis and exodermis to drought, exposure to moist air, flooding, salinity, ion deficiency, acidity, and mechanical impedance are discussed.

Frequency Estimation of Internet Packet Streams with Limited Space

Abstract: We consider a router on the Internet analyzing the statistical properties of a TCP/IP packet stream. A fundamental difficulty with measuring traffic behavior on the Internet is that there is simply too much data to be recorded for later analysis, on the order of gigabytes a second. As a result, network routers can collect only relatively few statistics about the data. The central problem addressed here is to use the limited memory of routers to determine essential features of the network traffic stream. A particularly difficult and representative subproblem is to determine the top k categories to which the most packets belong, for a desired value of k and for a given notion of categorization such as the destination IP address.We present an algorithm that deterministically finds (in particular) all categories having a frequency above 1/(m+1) using m counters, which we prove is best possible in the worst case. We also present a sampling-based algorithm for the case that packet categories follow an arbitrary distribution, but their order over time is permuted uniformly at random. Under this model, our algorithm identifies flows above a frequency threshold of roughly 1/?nm with high probability, where m is the number of counters and n is the number of packets observed. This guarantee is not far off from the ideal of identifying all flows (probability 1/n), and we prove that it is best possible up to a logarithmic factor. We show that the algorithm ranks the identified flows according to frequency within any desired constant factor of accuracy.

Multicomponent reactive transport modeling in variably saturated porous media using a generalized formulation for kinetically controlled reactions

Abstract: [1] A generalized formulation for kinetically controlled reactions has been developed and incorporated into a multicomponent reactive transport model to facilitate the investigation of a large variety of problems involving inorganic and organic chemicals in variably saturated media. The general kinetic formulation includes intra-aqueous and dissolution-precipitation reactions in addition to geochemical equilibrium expressions for hydrolysis, aqueous complexation, oxidation-reduction, ion exchange, surface complexation, and gas dissolution-exsolution reactions. The generalized approach allows consideration of fractional order terms with respect to any dissolved species in terms of species activities or in terms of total concentrations, which facilitates the incorporation of a variety of experimentally derived rate expressions. Monod and inhibition terms can be used to describe microbially mediated reactions or to limit the reaction progress of inorganic reactions. Dissolution-precipitation reactions can be described as surface-controlled or transport-controlled reactions. The formulation also facilitates the consideration of any number of parallel reaction pathways, and reactions can be treated as irreversible or reversible processes. Two groundwater contamination scenarios, both set in variably saturated media but with significantly different geochemical reaction networks, are investigated and demonstrate the advantage of the generalized approach. The first problem focuses on a hypothetical case study of the natural attenuation of organic contaminants undergoing dissolution, volatilization, and biodegradation in an unconfined aquifer overlaid by unsaturated sediments. The second problem addresses the generation of acid mine drainage in the unsaturated zone of a tailings impoundment at the Nickel Rim Mine Site near Sudbury, Ontario, and subsequent reactive transport in the saturated portion of the tailings.

Biotechnology and bioremediation: successes and limitations.

Abstract: With advances in biotechnology, bioremediation has become one of the most rapidly developing fields of environmental restoration, utilizing microorganisms to reduce the concentration and toxicity of various chemical pollutants, such as petroleum hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters, nitroaromatic compounds, industrial solvents, pesticides and metals. A number of bioremediation strategies have been developed to treat contaminated wastes and sites. Selecting the most appropriate strategy to treat a specific site can be guided by considering three basic principles: the amenability of the pollutant to biological transformation to less toxic products (biochemistry), the accessibility of the contaminant to microorganisms (bioavailability) and the opportunity for optimization of biological activity (bioactivity). Recent advances in the molecular genetics of biodegradation and studies on enzyme-tailoring and DNA-shuffling are discussed in this paper.

Conservation of Biodiversity in a Changing Climate

Abstract: *Center for Applied Biodiversity Science, Conservation International, Washington, D.C, 20037, U.S.A.†Climate Change Research Group, Ecology and Conservation, National Botanical Institute, Cape Town, South Africa‡The World Bank, Washington, D.C. 20433, U.S.A.§Botany Department, University of Cape Town, Cape Town, South Africa**Department of Biological Sciences, College of Science and Liberal Arts, Florida Institute of Technology, Melbourne,FL 32901–6975, U.S.A.††Environment Department, University of York, York, Y010 5DD, United Kingdom‡‡Adaptation and Impacts Research Group, Environment Canada at the Faculty of Environmental Studies, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada§§Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom

Examining the roles of job involvement and work centrality in predicting organizational citizenship behaviors and job performance

Abstract: A recent meta-analysis by Brown (1996) concluded that job involvement was unrelated to job performance. The present investigation proposed that the null findings reported in this meta-analysis stem from the choice of performance criteria and the use of job involvement measures that are confounded with work centrality in the primary studies included in the meta-analysis. The current study found that job involvement, when assessed with a recently published measure (Paullay et al., 1994), is a significant predictor of supervisor ratings of organizational citizenship behaviors (OCB) and in-role performance, controlling for work centrality and other individual difference variables. Consistent with recent findings, there is evidence that sex moderates some of the job involvement and OCB relationships, with females having a stronger, positive relationship between these constructs than males. Copyright © 2001 John Wiley & Sons, Ltd.

History and timing of human impact on Lake Victoria, East Africa.

Abstract: Lake Victoria, the largest tropical lake in the world, suffers from severe eutrophication and the probable extinction of up to half of its 500+ species of endemic cichlid fishes. The continuing degradation of Lake Victoria's ecological functions has serious long-term consequences for the ecosystem services it provides, and may threaten social welfare in the countries bordering its shores. Evaluation of recent ecological changes in the context of aquatic food-web alterations, catchment disturbance and natural ecosystem variability has been hampered by the scarcity of historical monitoring data. Here, we present high-resolution palaeolimnological data, which show that increases in phytoplankton production developed from the 1930s onwards, which parallels human-population growth and agricultural activity in the Lake Victoria drainage basin. Dominance of bloom-forming cyanobacteria since the late 1980s coincided with a relative decline in diatom growth, which can be attributed to the seasonal depletion of dissolved silica resulting from 50 years of enhanced diatom growth and burial. Eutrophication-induced loss of deep-water oxygen started in the early 1960s, and may have contributed to the 1980s collapse of indigenous fish stocks by eliminating suitable habitat for certain deep-water cichlids. Conservation of Lake Victoria as a functioning ecosystem is contingent upon large-scale implementation of improved land-use practices.

Strategies for Dynamic Stability During Locomotion on a Slippery Surface: Effects of Prior Experience and Knowledge

Abstract: Falls due to slips are prevalent in everyday life. The purpose of this study was to determine the reactive recovery responses used to maintain dynamic stability during an unexpected slip, establish the time course of response adaptation to repeated slip perturbations, and distinguish the proactive strategies for negotiating a slippery surface. Twelve young adults participated in the study in which a slip was generated following foot contact on a set of steel free-wheeling rollers. Surface electromyographic (EMG) data were collected from rectus femoris, biceps femoris, tibialis anterior, and the medial head of gastrocnemius on the perturbed limb. Whole body kinematics were recorded using an optical imaging system: from this the center of mass, foot angle, and medial-lateral stability margins were determined. In addition, braking/loading and accelerating/unloading impulses while in contact with the rollers and the rate of loading the rollers were determined from ground reaction forces. Results demonstrate that the reactive recovery response to the first slip consisted of a rapid onset of a flexor synergy (146-199 ms), a large arm elevation strategy, and a modified swing limb trajectory. With repeated exposure to the slip perturbation, the CNS rapidly adapts within one slip trial through global changes. These changes include the attenuation of muscle response magnitude, reduced braking impulse, landing more flat-footed, and elevating the center of mass. Individuals implement a "surfing strategy" while on the rollers when knowledge of the surface condition was available before hand. Furthermore, knowledge of a slip results in a reduced braking impulse and rate of loading, a shift in medial-lateral center of mass closer to the support limb at foot contact on the rollers and a more flat foot landing. In conclusion, prior experience with the perturbations allows subsequent modification and knowledge of the surface condition results in proactive adjustments to safely traverse the slippery surface.

Dietary essential fatty acids and brain function: a developmental perspective on mechanisms

Abstract: Brain development is a complex interactive process in which early disruptive events can have long-lasting effects on later functional adaptation. It is a process that is dependent on the timely orchestration of external and internal inputs through sophisticated intra- and intercellular signalling pathways. Long-chain polyunsaturated fatty acids (LCPUFA), specifically arachidonic acid and docosahexaenoic acid (DHA), accrue rapidly in the grey matter of the brain during development, and brain fatty acid (FA) composition reflects dietary availability. Membrane lipid components can influence signal transduction cascades in various ways, which in the case of LCPUFA include the important regulatory functions mediated by the eicosanoids, and extend to long-term regulation through effects on gene transcription. Our work indicates that FA imbalance as well as specific FA deficiencies can affect development adversely, including the ability to respond to environmental stimulation. For example, although the impaired water-maze performance of mice fed a saturated-fat diet improved in response to early environmental enrichment, the brains of these animals showed less complex patterns of dendritic branching. Dietary n-3 FA deficiency influences specific neurotransmitter systems, particularly the dopamine systems of the frontal cortex. We showed that dietary deficiency of n-3 FA impaired the performance of rats on delayed matching-to-place in the water maze, a task of the type associated with prefrontal dopamine function. We did not, however, find an association over a wider range of brain DHA levels and performance on this task. Some, but not all, studies of human infants suggest that dietary DHA may play a role in cognitive development as well as in some neurodevelopmental disorders; this possibility has important implications for population health.

Environmental Demands Associated With Community Mobility in Older Adults With and Without Mobility Disabilities

Abstract: Background and Purpose. In this study, the influence of 8 dimensions of the physical environment on mobility in older adults with and without mobility disability was measured. This was done in order to identify environmental factors that contribute to mobility disability. Subjects. Subjects were 36 older adults (≥70 years of age) who were recruited from 2 geographic sites (Seattle, Wash, and Waterloo, Ontario, Canada) and were grouped according to level of mobility function (physically able [ability to walk ½ mile (0.8 km) or climb stairs without assistance], physically disabled). Methods. Subjects were observed and videotaped during 3 trips into the community (trip to grocery store, physician visit, recreational trip). Frequency of encounters with environmental features within each of the 8 dimensions was recorded. Differences in baseline characteristics and environmental encounters were analyzed using an analysis of variance or the Fisher exact test, as appropriate. Results. Mobility disability among older adults was not associated with a uniform decrease in encounters with environmental challenges across all dimensions. Environmental dimensions that differed between subjects who were physically able and those with physical disability included temporal factors, physical load, terrain, and postural transition. Dimensions that were not different included distance, density, ambient conditions (eg, light levels and weather conditions), and attentional demands. Discussion and Conclusion. Understanding the relationship of the environment to mobility is crucial to both prevention and rehabilitation of mobility disability in older adults. Among older adults, certain dimensions of the environment may disable community mobility more than others.

Age-dependent variations in the directional sensitivity of balance corrections and compensatory arm movements in man

Abstract: We investigated the effects of ageing on balance corrections induced by sudden stance perturbations in different directions. Effects were examined in biomechanical and electromyographic (EMG) recordings from a total of 36 healthy subjects divided equally into three age groups (20-34, 35-55 and 60-75 years old). Perturbations consisted of six combinations of support-surface roll (laterally) and pitch (forward-backward) each with 7.5 deg amplitude (2 pure pitch, and 4 roll and pitch) delivered randomly. To reduce stimulus predictability further and to investigate scaling effects, perturbations were at either 30 or 60 deg s(-1). In the legs, trunk and arms we observed age-related changes in balance corrections. The changes that appeared in the lower leg responses included smaller stretch reflexes in soleus and larger reflexes in tibialis anterior of the elderly compared with the young. For all perturbation directions, onsets of balance correcting responses in these ankle muscles were delayed by 20-30 ms and initially had smaller amplitudes (between 120-220 ms) in the elderly. This reduced early activity was compensated by increased lower leg activity after 240 ms. These EMG changes were paralleled by comparable differences in ankle torque responses, which were initially (after 160 ms) smaller in the elderly, but subsequently greater (after 280 ms). Findings in the middle-aged group were generally intermediate between the young and the elderly groups. Comparable results were obtained for the two different stimulus velocities. Stimulus-induced trunk roll, but not trunk pitch, changed dramatically with increasing age. Young subjects responded with early large roll movements of the trunk in the opposite direction to platform roll. A similarly directed but reduced amplitude of trunk roll was observed in the middle-aged. The elderly had very little initial roll modulation and also had smaller stretch reflexes in paraspinals. Balance-correcting responses (over 120-220 ms) in gluteus medius and paraspinals were equally well tuned to roll in the elderly, as in the young, but were reduced in amplitude. Onset latencies were delayed with age in gluteus medius muscles. Following the onset of trunk and hip balance corrections, trunk roll was in the same direction as support-surface motion for all age groups and resulted in overall trunk roll towards the fall side in the elderly, but not in the young. Protective arm movements also changed with age. Initial arm roll movements were largest in the young, smaller in the middle aged, and smallest in the elderly. Initial arm roll movements were in the same direction as initial trunk motion in the young and middle aged. Thus initial roll arm movements in the elderly were directed oppositely to those in the young. Initial pitch motion of the arms was similar across age groups. Subsequent arm movements were related to the amplitude of deltoid muscle responses which commenced at 100 ms in the young and 20-30 ms later in the elderly. These deltoid muscle responses preceded additional arm roll motion which left the arms directed 'downhill' (in the direction of the fall) in the elderly, but 'uphill' (to counterbalance motion of the pelvis) in the young. We conclude that increased trunk roll stiffness is a key biomechanical change with age. This interferes with early compensatory trunk movements and leads to trunk displacements in the direction of the impending fall. The reversal of protective arm movements in the elderly may reflect an adaptive strategy to cushion the fall. The uniform delay and amplitude reduction of balance-correcting responses across many segments (legs, hips and arms) suggests a neurally based alteration in processing times and response modulation with age. Interestingly, the elderly compensated for these 'early abnormalities' with enlarged later responses in the legs, but no similar adaptation was noted in the arms and trunk. These changes with age provide an insight into possible mechanisms underlying falls in the elderly.

Climatic influence on a marine fish assemblage

Abstract: Understanding the fluctuations in marine fish stocks is important for the management of fisheries, and attempts have been made to demonstrate links with oceanographic and climatic variability1,2,3, including the North Atlantic Oscillation (NAO)4,5. The NAO has been correlated with a range of long-term ecological measures6,7, including certain fish stocks8,9. Such environmental influences are most likely to affect susceptible juveniles10 during estuarine residency, as estuaries are critical juvenile nursery or over-wintering habitats11. Here we show that, during a 16-year period, climatic forcing (by means of the NAO) is consistently the most important parameter explaining variation in assemblage composition, abundance and growth of juvenile marine fish during estuarine residency. A possible mechanism for the effect of the NAO is a temperature differential between estuarine and marine waters that allows fish to facultatively exploit optimal thermal habitats. The connection has potentially important implications for the size and numbers of individuals recruited to the fishery, for understanding and predicting the composition of juvenile fish stocks using estuaries, and for the appropriate conservation of estuarine systems in relation to fish stocks.

Integral moments of L-functions

Abstract: We give a new heuristic for all of the main terms in the integral moments of various families of primitive L-functions. The results agree with previous conjectures for the leading order terms. Our conjectures also have an almost identical form to exact expressions for the corresponding moments of the characteristic polynomials of either unitary, orthogonal, or symplectic matrices, where the moments are defined by the appropriate group averages. This lends support to the idea that arithmetical L-functions have a spectral interpretation, and that their value distributions can be modeled using Random Matrix Theory. Numerical examples show good agreement with our conjectures.

Fear of falling modifies anticipatory postural control

Abstract: This study investigated the influence of fear of falling or postural threat on the control of posture and movement during a voluntary rise to toes task for 12 healthy young adults. Postural threat was modified through alterations to the surface height at which individuals stood (low or high platform) and changes in step restriction (away from or at the edge of the platform) creating four levels of postural threat: LOW AWAY, LOW EDGE, HIGH AWAY and HIGH EDGE. To rise to the toes, an initial postural adjustment must destabilise the body so that it can be moved forward and elevated to a new position of support over the toes. Centre of pressure and centre of mass profiles, as well as tibialis anterior (TA), soleus (SO) and gastrocnemius (GA) muscle activity patterns were used to describe this behaviour. The results showed that the performance of the rise to toes task was significantly modified when positioned at the edge of the high platform. In this situation, the central nervous system reduced the magnitude and rate of the postural adjustments and subsequent voluntary movement. Although the duration of the movement was lengthened for this most threatening condition, the sequencing and relative timing of TA, SO and GA muscle activity was preserved. These changes in rise to toes behaviour were accompanied by evidence of increased physiological arousal and participant reports of decreased confidence, increased anxiety and decreased stability. Evidence of fear of falling effects on anticipatory postural control is clinically relevant as it may explain deficits in this control observed in individuals with balance disorders. For example, individuals with Parkinson’s disease or cerebellar dysfunction demonstrate impaired performance on the rise to toes task as reflected in alterations of both the timing and magnitude of their anticipatory postural adjustments. Our findings suggest alterations in the magnitude of postural adjustments may be magnified by fear of falling while changes in the timing of postural adjustments may reflect underlying pathology.

A note on the judgmental effects of the balanced scorecard's information organization

Abstract: We examine judgmental effects of the balanced scorecard’s organization. The balanced scorecard contains a large number of performance measures divided into four categories. We examine whether the scorecard’s organization results in managerial performance evaluation judgments consistent with a recognition of the potential relations (i.e. nonindependence) of measures within a category. Supporting this idea, we find that performance evaluations are affected by organizing the measures into the balanced scorecard categories when multiple below-target (or above-target) measures are contained within a category but that evaluations are not affected when the above/below-target measures are distributed across the scorecard’s four categories. # 2002 Elsevier Science Ltd. All rights reserved.