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Showing papers by "University of Ottawa published in 1987"


Journal ArticleDOI
24 Sep 1987-Nature
TL;DR: In this paper, the authors examined the spatial distributions of trees in North America to determine which characteristics of the environment are most closely related to the species richness of different regions and found that topography and proximity to the sea are significantly related to residual variation, whereas seasonal climatic variability and glacial history are not.
Abstract: Biologists have long recognized the striking geographical variability of species richness1. A primary goal of contemporary ecology is to identify the factors responsible for this variability2. We have examined the spatial distributions of trees in North America to determine which characteristics of the environment are most closely related to the species richness of different regions. Realized annual evapotranspiration, which is correlated with primary production and is therefore a measure of available energy, statistically explains 76% of the variation in species richness. Topography and proximity to the sea are significantly related to the residual variation, whereas seasonal climatic variability and glacial history are not. Tree richness in Great Britain and Ireland can be accurately predicted from these North American patterns. Our data are best explained by the hypothesis that contemporary available energy limits species richness3,4.

671 citations


Journal ArticleDOI
TL;DR: In this article, a detailed experimental and mechanistic analysis of the elementary surface-chemical steps involved in the beginning stages of electrooxidation of Au is given with respect to the processes that occur on the (111) plane.

480 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that interpretation of ac impedance measurements directly in terms of the components of an intuitively assumed equivalent circuit is rarely correct; only in the case of underpotential-deposition of an ad-species, where no continuous Faradaic currents pass, in such an approach satisfactory.

440 citations


OtherDOI
TL;DR: The sections in this article are: Event-Related Potentials, ERPs and Cognitive Processing, Language and Hemispheric Specialization, and Concluding Observations.
Abstract: The sections in this article are: 1 Event-Related Potentials 1.1 Classification 1.2 Nomenclature 1.3 Recording Techniques 1.4 Measurement 2 Neural Bases of Event-Related Potentials 2.1 Field Potentials in the Nervous System 2.2 Scalp Distribution 2.3 Depth Recordings 2.4 Event-Related Magnetic Fields 2.5 Blood Flow and Metabolism 3 Clinical Applications of Event-Related Potentials 3.1 Evaluation of Sensory Function 3.2 Applications to Neurology 3.3 Disorders of Higher Nervous Functions 4 Preparation and Anticipation 4.1 Movement-Related Potentials 4.2 Contingent Negative Variation 4.3 Clinical Studies 5 Selective Attention 5.1 Early ERP Experiments 5.2 Auditory Attention 5.3 Interpretation of Auditory Negative-Difference Wave 5.4 Visual Attention 5.5 Somatosensory Attention 5.6 Question of Peripheral Sensory Gating 5.7 Attentional Channels 5.8 Multidimensional Stimulus Selection 5.9 Disorders of Attention 5.10 Overview: ERPs and Selective Attention 6 Cognitive Processing 6.1 Stimulus Probability and Expectancy 6.2 Signal Detection and Decision Confidence 6.3 Stimulus Relevance 6.4 Stimulus-Evaluation Processes 6.5 Mental Chronometry 6.6 Stimulus Meaning 6.7 Cognitive ERPs in Children 6.8 Aging and Dementia 6.9 Psychiatric Conditions 6.10 Animal Models of ERPs 6.11 Overview: ERPs and Cognitive Processing 7 Language and Hemispheric Specialization 7.1 ERPs Preceding Speech 7.2 Auditory ERPs to Speech Sounds 7.3 Phonetic Processing 7.4 Visual ERPs to Words 7.5 Probe-Stimulus Technique 7.6 Linguistic Decision Making 7.7 Stimulus Meaning 7.8 Contextual Effects in Language 7.9 Semantic Mismatch and Semantic Priming 7.10 Language Disorders 7.11 Overview: ERPs and Language 8 Concluding Observations

398 citations


Journal ArticleDOI
TL;DR: The authors reviewed the offender rehabilitation literature for the period 1981-87 and assessed the following types of interventions: biomedical, diversion, early/family intervention, education, getting tough, individual differences, parole/probation, restitution, and work.
Abstract: We reviewed the offender rehabilitation literature for the period 1981–87 and assessed the following types of interventions: biomedical, diversion, early/family intervention, education, getting tough, individual differences, parole/probation, restitution, and work. We evaluated treatments applied to specific subgroups of offender populations: sexual offenders, substance abusers, and violent offenders. The hypothesis that the “nothing works” credo has had a pervasive influence and has suppressed the rehabilitative agenda was not borne out when we examined the number and variety of successfully reported attempts at reducing delinquent behavior. In fact, the rehabilitative literature is growing at a noticeable rate; moreover, it suggests several strategies for developing more effective programs. Finally, we speculated why the “nothing works” doctrine continues to receive support in spite of empirical evidence to the contrary.

388 citations


Journal ArticleDOI
01 Jan 1987-Gene
TL;DR: A number of conserved motifs in the promoter may indicate a significant role for these sequences in expression of the pgk-1 gene, which is contained within a 16-kb region of the X chromosome.

356 citations


Journal ArticleDOI
TL;DR: In this paper, the set of Pareto optimal paths in multiple-objective, shortest-path problems is approximated by a fully polynomial approximation method, that is, they operate in time and space bounded by the problem size and accuracy.
Abstract: We study methods for approximating the set of Pareto optimal paths in multiple-objective, shortest-path problems. Known generalizations of standard shortest-path methods will compute this set, but can suffer from rapidly increasing computational and storage demands as problem size increases. In an effort to avoid such difficulties, we develop approximation methods that can estimate the Pareto optima to any required degree of accuracy. The approximation methods are "fully polynomial"; that is, they operate in time and space bounded by a polynomial in problem size and accuracy of approximation-the greater the accuracy, the more time required to reach a solution. We show how approximation methods may be applied to yield fully polynomial approximation schemes for a variety of NP-complete, single-objective problems.

312 citations


Journal ArticleDOI
TL;DR: The characterization of the most abundant of these sequences (TRPM-2), and the kinetics of the induction of this gene in the prostate after castration are reported, and it is reported that this gene may play an important role in the process of tissue regression.

250 citations


Journal Article
TL;DR: A greater than expected proportion of patients had a smoking history, preexisting pulmonary disease and were male, and prognosis was better in those patients treated with corticosteroids.
Abstract: Methotrexate pneumonitis is emerging as one of the most unpredictable and potentially serious adverse effects associated with the use of low dose, pulse methotrexate in treating rheumatoid arthritis (RA). We report 4 new cases of methotrexate pneumonitis in patients with RA and review 6 published cases. A greater than expected proportion of patients had a smoking history, preexisting pulmonary disease and were male. Prognosis was better in those patients treated with corticosteroids.

234 citations


Journal ArticleDOI
TL;DR: Formulas are presented for simulating bone, lung, brain, and muscle tissue in the frequency range of 100 MHz to 1 GHz, and by using these preparations a realistic equivalent to the human body can be constructed.
Abstract: For the study of electromagnetic dosimetry and hyperthermia, it is necessary to simulate human biological materials. This can be done by chemical mixtures that are described in this paper. Formulas are presented for simulating bone, lung, brain, and muscle tissue in the frequency range of 100 MHz to 1 GHz. By using these preparations a realistic equivalent to the human body can be constructed.

221 citations


Journal ArticleDOI
TL;DR: In this article, the authors tested the invariance of a multidimensional, hierarchical self-concept (SC) structure for adolescent males and females, and found significant gender differences in the reliability of certain measurement scales, and correlated errors of measurement were more prevalent for males than for females.
Abstract: This study tested the invariance of a multidimensional, hierarchical self-concept (SC) structure for adolescent males and females. In a covariance structure analysis of data from a sample of 832 (412 males, 420 females) grade 11 and 12 students, with multiple measures of general, academic, English, and mathematics SC facets, SC structure differed for males and females. Although the number of SC factors, pattern of factor loadings (except for one), and hierarchical structure were invariant across gender, relations among the factors differed. These structural differences derived largely from the differential way in which English and mathematics SC related to the other SC facets, and to grades, for each sex. In addition, significant gender differences were found in the reliability of certain measurement scales, and correlated errors of measurement were more prevalent for males than for females. The study has important implications for substantive research that focuses on the comparison of SCs across groups a...

Journal ArticleDOI
TL;DR: In this article, the behavior of the opd H species in the H 2 evolution reaction (h.r) proceeding with appreciable net cathodic current at activated and unactivated rotated Pt electrodes is investigated by means of impedance spectrum measurements.

Journal ArticleDOI
TL;DR: In this paper, the authors compared three tests reported sensitive to attentional disorder or limitations in information processing capacity after closed-head injury, and provided some normative data on these three tests.
Abstract: The purpose of this study was to compare three tests reported sensitive to attentional disorder or limitations in information-processing capacity after closed-head injury, and to provide some normative data on these three tests. The Trail Making Test (TMT), the Brown-Peterson test of memory of three consonants (CCC) under conditions of interference, and the Paced Auditory Serial-Addition Test (PASAT) were compared across six age groups for two separate test administrations. The possible influences of gender and years of education were also analyzed. There was a practice effect for all tests. Age appeared to be a factor primarily for the TMT, the older subjects being slower. Years of education correlated with PASAT findings and to a lesser degree with the TMT. Sex did not have a significant effect on any of the test results. The CCC was least affected by any of the moderator variables used in this study. Although these three tests appear comparable in measuring attention or information-processing ...

Journal ArticleDOI
TL;DR: Comparison of curvilinear regression of foot length versus gestational age demonstrated a strong correlation with an R2 value of 0.981; 95% confidence intervals at each week compared favorably with both biparietal diameter and femur length data.

Journal ArticleDOI
TL;DR: The nucleotide sequence of the pgK-2 gene suggests that it arose from pgk-1 more than 100 million years ago by RNA-mediated gene duplication, and gene duplication by retroposition may have been used as a mechanism for evolutionary diversification.
Abstract: In both humans and mice, two genes encode phosphoglycerate kinase, a key enzyme in the glycolytic pathway. The pgk-1 gene is expressed in all somatic cells, is located on the X chromosome, and contains 10 introns. The pgk-2 gene is expressed only in sperm cells, is located on an autosome, and has no introns. The nucleotide sequence of the pgk-2 gene suggests that it arose from pgk-1 more than 100 million years ago by RNA-mediated gene duplication. The pgk-2 gene may, then, be a transcribed retroposon. Thus, gene duplication by retroposition may have been used as a mechanism for evolutionary diversification.

Journal ArticleDOI
TL;DR: In this paper, the authors present the concepts, complete examples, and interpretations for four methods of testing differences among means in a mixed model repeated measures design, including the traditional ANOVA and the MANOVA method for the single dependent variable case, and a Multivariate Mixed Model analysis and a Doubly Multivariate analysis for the multiple dependent variables case.
Abstract: Experimental designs involving repeated measures may be analyzed using traditional ANOVA methods (if all assumptions are met), or, given sufficient sample size, with a MANOVA-type procedure (if only some assumptions are met). Recent statistical advances have made possible the extension of these procedures to repeated measures experimental designs involving multiple dependent variables. This tutorial presents the concepts, complete examples (including computer control commands), and interpretations for four methods of testing differences among means in a mixed model repeated measures design. The four methods of analysis are: The traditional ANOVA and the MANOVA method for the single dependent variable case, and a Multivariate Mixed Model analysis and a Doubly Multivariate analysis for the multiple dependent variable case.

Journal ArticleDOI
TL;DR: A multivariate prognostic factor analysis demonstrated that for lung cancer, the percent of weight loss, serum albumin concentration, and presence of liver metastases were significant and independent prognostic variables for survival duration and for colorectal cancer, serumalbumin, alkaline phosphatase, lactic dehydrogenase levels, and percent targeted caloric intake were significant independent predictors of survival duration.
Abstract: One hundred ninety-two patients with previously untreated metastatic cancer (102 non-small-cell lung cancer [NSCLC]; 90 colorectal cancer) were randomized to receive either ad lib nutritional intake (control group) or specific nutritional intervention during a 12-week study period when chemotherapy was administered. Those patients randomized to nutritional interventions were counselled to take oral nutrients with caloric intake equal to 1.7 to 1.95 times their basal energy expenditure, depending on their pretreatment nutritional status ("standard" group). An augmented group was counselled to have a caloric intake equivalent to that of the standard group but with 25% of calories provided as protein and additional supplements of zinc and magnesium. Counselling increased caloric intake in both tumor types but reduced weight loss in the short term only for lung cancer patients. Ninety-three NSCLC patients were evaluable for tumor response to vindesine and cisplatin. Overall, only 20.4% of the patients responded, and there were no significant differences in response rates, median time to progression, or overall duration of survival between the nutrition intervention groups and the control group. The tumor response rate to time-sequenced 5-fluorouracil (5-FU) and methotrexate in the 81 evaluable patients with colorectal cancer was only 14.8%, and no significant differences in tumor response rates were noted between the three groups. Furthermore, the median time to progression and overall duration of survival were not different for the control, standard, and augmented groups. Nutritional interventions using dietary counselling had no impact on the percent of planned chemotherapy dose administered, the degree of toxicity experienced by patients, or the frequency of treatment delays. A multivariate prognostic factor analysis demonstrated that for lung cancer, the percent of weight loss, serum albumin concentration, and presence of liver metastases were significant (P less than .05) and independent prognostic variables for survival duration. For colorectal cancer, serum albumin, alkaline phosphatase, lactic dehydrogenase (LDH) levels, and percent targeted caloric intake (TCI) were significant independent predictors of survival duration.

Journal ArticleDOI
TL;DR: There was no effect of attention on the amplitude and phase of the steady-state evoked potentials when subjects either counted successive increments in stimulus intensity or read a book.

Book ChapterDOI
TL;DR: In this article, the authors reformulated the community-unit and individualistic concepts of plant communities as hypotheses concerning the distribution of species' boundaries along a gradient, and tested these hypotheses by an analysis of deviance on data derived from a direct-gradient analysis of a freshwater marsh plant community in Breckenridge, Quebec, Canada.
Abstract: This study reformulates the community-unit and individualistic concepts of plant communities as hypotheses concerning the distribution of species' boundaries along a gradient. These hypotheses are tested by an analysis of deviance on data derived from a direct-gradient analysis of a freshwater marsh plant community in Breckenridge, Quebec, Canada. Boundaries are clustered at certain intervals along the gradient (p<0.001), contradicting the individualistic hypothesis. Upper boundaries are not consistently clustered at the same intervals as lower boundaries (p<0.001), contradicting the community-unit hypothesis. Thus, neither of the two usual models of community structure explain the patterns found in Breckenridge Marsh, suggesting that the historical dichotomy is too limited. Hypotheses of pattern should be tested using inferential statistics. Hypotheses of mechanism should be tested by experimentation. The way out of the community-unit vs. individualistic community debate is to deny the dichotomy and to consider multiple working hypotheses of community structure.

Journal ArticleDOI
TL;DR: Fatigue, the effect of fatigue on an individually pre-selected activity and its effect on activities of daily living, were evaluated and amantadine produced a small but statistically significant decrease in fatigue.

Journal ArticleDOI
TL;DR: In this paper, the Stokes and Brinkman equations were used to solve the Creeping Flow Past a Solid Sphere with a Porous Shell (CF-shell) problem, where the dimensionless solid core and shell radii normalized by the square root of the shell permeability are the two parameters that govern the flow.

Journal ArticleDOI
TL;DR: The steady-state evoked potentials are most efficiently recorded using Fourier analysis, and the response to 500 Hz tones presented at a rate of 40/sec can be reliably recognized on average down to intensities of below 15 dB SL in an awake subject.

Journal ArticleDOI
TL;DR: When serotonin is injected directly into the ventricle of these fish it briefly inhibits chirping (aggression) without inhibiting the JAR; this is consistent with the hypothesis that, in mammals, serotonin inhibits aggressive behaviour.

Journal ArticleDOI
TL;DR: It is concluded that the stretch-sensitive kinetic component of theHeart ventricle cells of Lymnaea stagnalis contain a stretch-activated K + channel which exhibits two open states and three closed states.
Abstract: Heart ventricle cells of Lymnaea stagnalis contain a stretch-activated K + channel which exhibits two open states and three closed states. Over the range 0 to −25 mmHg (1 mmHg = 133.3 Pa), the probability that the channel is open is a steeply non-linear function of negative pressure. Pressure-dependent decreases in the mean times of the longest component of the closed-time distribution are observed in the same range and (because other mean times show no consistent or sufficiently large changes with pressure) are assumed to account for increases in the probability of being open. Channel activity characteristically occurs as bursts with a mean time of 3.6 ms. These bursts contain, on average, 1.7 closings; 78 % of the burst time is spent in the open state. It is concluded that the stretch-sensitive kinetic component is an interburst closed state. Note: To whom reprint requests should be sent.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the evolution from 1980-1981 to 1984-1985 of 38 young firms originally created by entrepreneurs while at various universities in several Canadian provinces and found that the entrepreneurs staying close to the university and using university services may be less aggressive and less risk-oriented than the others.

Journal ArticleDOI
TL;DR: Differences across grade level in children's ability to encode descriptions of withdrawn behavior into memory and subsequently to retrieve the descriptions accurately were interpreted as evidence of the emerging importance of social withdrawal as a social-cognitive schema underlying children's social perceptions.
Abstract: This study examined the ability of children of different ages to encode and retrieve from memory descriptions of aggressive and withdrawn behavior displayed by hypothetical peers. 90 children from the first, third, fifth, and seventh grades (aged 6-7, 8-9, 10-11, 12-13, respectively) listened to behavioral descriptions of a hypothetical aggressive and a hypothetical withdrawn boy and subsequently reported their recollections for these descriptions. Differences across grade level were found in the number of behaviors correctly recalled for the withdrawn boy but not for the aggressive boy. At the first grade, children recalled fewer descriptions of withdrawn behavior than of aggressive behavior. However, recall for withdrawal increased significantly across grade level, such that at grades 5 and 7, subjects recalled more descriptions of withdrawn than of aggressive behavior. Such differences across grade level in children's ability to encode descriptions of withdrawn behavior into memory and subsequently to retrieve the descriptions accurately were interpreted as evidence of the emerging importance of social withdrawal as a social-cognitive schema underlying children's social perceptions.

Journal ArticleDOI
TL;DR: This review will critically evaluate the available information on what major factors influence the airborne survival of human and animal pathogenic viruses, and summarize the information from epidemiological studies documenting the airborne spread of viral infections.
Abstract: Viruses are responsible for a variety of diseases in humans as well as animals of economic importance. Although consumption of virus‐contaminated water and food is known to result in the spread of some of these diseases, air is now recognized as an important means for their transmission. Depending on environmental conditions, many of these viruses can survive in an airborne state anywhere from several hours to several days. This can result in the aerial dissemination of such infectious agents over distances of several kilometers. This review will critically evaluate the available information on what major factors influence the airborne survival of human and animal pathogenic viruses. It will also examine those published data where infectious viruses have been recovered from naturally contaminated atmosphere, and summarize the information from epidemiological studies documenting the airborne spread of viral infections. The existing gaps in our knowledge of this field will then be identified.

Journal ArticleDOI
TL;DR: The retrograde transport of wheat germ agglutinin conjugated horseradish peroxidase is used to study the afferent input to the various subdivisions of the caudal lobe of the high frequency gymnotid fish Apteronotus leptorhynchus to suggest a more complex organization of this projection.
Abstract: The caudal lobe of the cerebellum of the high frequency gymnotid fish Apteronotus leptorhynchus is that region of the cerebellum lying lateral to the posterolateral sulcus. It consists of three granular masses--the eminentia granularis posterior pars lateralis, a transitional zone T, and the eminentia granularis posterior pars medialis--with their associated molecular layers. We have used the retrograde transport of wheat germ agglutinin conjugated horseradish peroxidase to study the afferent input to the various subdivisions of the caudal lobe. Each granular mass receives different types of input. Eminentia granularis posterior pars lateralis receives a massive bilateral input from an isthmic nucleus, nucleus praeeminentialis, concerned with descending control of the electrosensory system and from a rhombencephalic nucleus, the lateral reticular nucleus, which itself receives a major spinal input. In addition eminentia granularis posterior receives lesser input from other pretectal, (N. at base of dorsomedial optic tract, pretectal complex "B") mesencephalic (dorsal tegmental N., nucleus raphe dorsalis), isthmic (bed N. of praeeminentialis-cerebellaris tract, locus coeruleus) and rhombencephalic nuclei (lateral tegmental N., eurydendroid cells, octaval N., perihypoglossal N., paramedian reticular N., medullary reticular formation, medullary raphe, efferent octavolateralis N., inferior olive, and funicular N.). The input from nucleus praeeminentialis dorsalis is mapped topographically onto eminentia granularis posterior with respect to their rostro-caudal location. We could not define any topography in the mapping of the dorso-ventral body axis upon eminentia granularis posterior; small injections of WGA-HRP produced several small clusters of labeled cells within nucleus praeeminentialis dorsalis which does suggest a more complex organization of this projection. Zone T receives most of its input from the ipsilateral VIIIth nerve ganglion cells and certain pretectal nuclei, but it also receives a small input from nucleus praeeminentialis dorsalis. Eminentia granularis posterior pars medialis receives minor input from a small pretectal nucleus and a small ventral diencephalic nucleus, this region appears to receive its major input from eurydendroid cells of eminentia granularis posterior. The molecular layer associated with each granular mass receives contralateral input from separate clusters of inferior olivary cells. In addition the eurydendroid cells (cerebellar output neurons) of eminentia granularis posterior pars lateralis receive a substantial direct input from cells located in the medial aspect of nucleus praeeminentialis dorsalis.


Journal ArticleDOI
TL;DR: In this paper, a new kinetic method for calculating the form of open-circuit potential decay transients has been developed and is applied to the hydrogen evolution reaction, with electrosorption, electrodesorption and recombination steps considered.