Showing papers by "Université de Montréal published in 1992"

Effect of captopril on mortality and morbidity in patients with left ventricular dysfunction after myocardial infarction. results of the survival and ventricular enlargement trial

Abstract: Background. Left ventricular dilatation and dysfunction after myocardial infarction are major predictors of death. In experimental and clinical studies, long-term therapy with the angiotensin-converting—enzyme inhibitor captopril attenuated ventricular dilatation and remodeling. We investigated whether captopril could reduce morbidity and mortality in patients with left ventricular dysfunction after a myocardial infarction. Methods. Within 3 to 16 days after myocardial infarction, 2231 patients with ejection fractions of 40 percent or less but without overt heart failure or symptoms of myocardial ischemia were randomly assigned to receive double-blind treatment with either placebo (1116 patients) or captopril (1115 patients) and were followed for an average of 42 months. Results. Mortality from all causes was significantly reduced in the captopril group (228 deaths, or 20 percent) as compared with the placebo group (275 deaths, or 25 percent); the reduction in risk was 19 percent (95 percent conf...

Quantum cryptography without Bell's theorem.

Abstract: Ekert has described a cryptographic scheme in which Einstein-Podolsky-Rosen (EPR) pairs of particles are used to generate identical random numbers in remote places, while Bell's theorem certifies that the particles have not been measured in transit by an eavesdropper. We describe a related but simpler EPR scheme and, without invoking Bell's theorem, prove it secure against more general attacks, including substitution of a fake EPR source. Finally we show our scheme is equivalent to the original 1984 key distribution scheme of Bennett and Brassard, which uses single particles instead of EPR pairs.

Nonstationarity and Level Shifts With an Application to Purchasing Power Parity

Abstract: This study considers testing for a unit root in a time series characterized by a structural change in its mean. The analysis is in the spirit of Perron (1990a), who showed that the existence of such a shift in a stationary time series biases the usual tests for a unit root toward nonrejection. The approach is, however, different given that we suppose the date of the change to be unknown. The statistic of interest is then the minimal t statistic over all possible breakpoints in regressions similar to those proposed by Perron (1990a). Other related statistics are also discussed. We derive and tabulate the asymptotic distributions of interest. Most of the emphasis, however, is given to the tabulation of finite-sample critical values using simulation experiments. Particular attention is given to the effect, on the finite-sample critical values, of various procedures to select the appropriate order of the estimated autoregressions. We apply the tests to analyze the issue of purchasing power parity between the ...

A tabu search heuristic for the vehicle routing problem

Abstract: The purpose of this paper is to describe TABUROUTE, a new tabu search heuristic for the vehicle routing problem with capacity and route length restrictions. The algorithm considers a sequence of adjacent solutions obtained by repeatedly removing a vertex from its current route, and reinserting it into another route. This is done by means of a generalized insertion procedure previously developed by the authors. During the course of the algorithm, infeasible solutions are allowed. Numerical tests on a set of benchmark problems indicate that tabu search outperforms the best existing heuristics, and TABUROUTE often produces the bes known solutions. (A)

Mental Disorder, Intellectual Deficiency, and Crime: Evidence From a Birth Cohort

Abstract: • Studies of criminality among patients in psychiatric hospitals and of mental disorder among incarcerated offenders have suggested an association between the major mental disorders (schizophrenia and major affective disorders) and crime. However, these investigations are characterized by notable methodological weaknesses, and, consequently, this conclusion has remained tentative. Little is known about the criminality of intellectually handicapped people. The present study examined the relationship between crime and mental disorder and crime and intellectual deficiency in an unselected Swedish birth cohort followed up to age 30 years. It was found that men with major mental disorders were 21/2 times more likely than men with no disorder or handicap to be registered for a criminal offense and four times more likely to be registered for a violent offense. Women with major disorders were five times more likely than women with no disorder or handicap to be registered for an offense and 27 times more likely to be registered for a violent offense. These subjects committed many serious offenses throughout their lives. The criminal behavior in over half these cases appeared before the age of 18 years. Intellectually handicapped men were three times more likely to offend than men with no disorder or handicap and five times more likely to commit a violent offense. Intellectually handicapped women were almost four times more likely to offend than women with no disorder or handicap and 25 times more likely to commit a violent offense. The results of this investigation confirm and extend previous findings indicating that individuals with major mental disorders and those with intellectual handicaps are at increased risk for offending and for violent offending. However, in the United States, where rates of crime overall and crime by substance abusers are very high, the mentally disordered and intellectually handicapped would account for only a small proportion of these offenses.

The integer l-shaped method for stochastic integer programs with complete recourse

Abstract: In this paper, a general branch-and-cut procedure for stochastic integer programs with complete recourse and first stage binary variables is presented. It is shown to provide a finite exact algorithm for a number of stochastic integer programs, even in the presence of binary variables or continous random variables in the second stage. (A)

The nitrogen : phosphorus relationship in lakes

Abstract: Published data on mean annual epilimnetic total N (TN) and P (TP) were analyzed to find how TN : TP varies with lake trophic status. TN : TP is high in oligotrophic lakes and very low in eutrophic lakes, declining in a curvilinear fashion with increased TP. Comparison of this trend with published N : P in lake nutrient sources suggests that TN : TP reflects the source of nutrients: the ratio is high in oligotrophic lakes because they receive their N and P from natural, undisturbed watersheds which export much less P than N; mesotrophic and eutrophic lakes receive various mixtures of nutrient sources that have lower average N : P, and very eutrophic lakes have N : P that correspond very nearly to the N : P of sewage. Two inflection points were identified in the TN : TP relationship (-20 and - 100 wg TP liter-l) the first probably reflecting the large difference between TN : TP in nutrient export from undisturbed terrestrial ecosystems and that of meso- and eutrophic sources such as urban and pasture land runoff and sewage, and the second probably reflecting increased rates of denitrification in eutrophic lakes. Analysis of published manipulation experiments shows that N limitation is not only significantly more frequent in lakes of low ambient TN: TP (TN: TP mass ratio 5 14) but is also significantly more frequent in lakes with TP > 30 wg liter’.

Detection and localization of parathyroid adenomas in patients with hyperparathyroidism using a single radionuclide imaging procedure with technetium-99m-sestamibi (double-phase study)

Abstract: Dual radionuclide imaging using a combination of 201Tl with either 99mTcO4- or 123I is recognized as a useful procedure in the preoperative localization of parathyroid adenomas. Recently, 99mTc-sestamibi (MIBI) has been introduced for myocardial perfusion imaging as an alternative to 201Tl. The purpose of this prospective study was to evaluate parathyroid scan using early and late imaging following MIBI injection. Twenty-three patients (21 F, 2 M, mean age: 57 yr) with a clinical and biologic diagnosis of hyperparathyroidism were submitted to a MIBI study prior to surgical exploration of the neck. Cervico-thoracic planar imaging (anterior view, 10 min/view) was performed at 15 min and at 2-3 hr after an intravenous injection of 20-25 mCi of MIBI. A positive MIBI scan for parathyroid adenoma was defined as an area of increased focal uptake which persisted on late imaging, contrary to the uptake in the normal thyroid tissue which progressively decreases over time (differential washout). Surgical exploration of the neck, performed between 1 day and 72 days (average: 16 days) after the MIBI study, showed a parathyroid adenoma in 21 patients and hyperplasia in two patients. MIBI scan correctly detected and localized 19/21 adenomas (90%). In conclusion, parathyroid imaging using a single radionuclide with MIBI (early and late study with differential washout analysis) is a promising procedure in the preoperative detection and localization of parathyroid adenomas in patients with primary hyperparathyroidism.

Bronchogenic carcinoma: analysis of staging in the mediastinum with CT by correlative lymph node mapping and sampling.

Abstract: One hundred forty-three patients with bronchogenic carcinoma were studied prospectively with computed tomography (CT) to determine the accuracy of CT in the evaluation of mediastinal nodal metastases. Mediastinal lymph nodes were localized according to the lymph node mapping scheme of the American Thoracic Society and were considered abnormal if they exceeded 1 cm in short-axis diameter. All patients underwent surgical staging, which consisted of either mediastinoscopy alone or mediastinoscopy and thoracotomy. At the time of surgical staging, all accessible nodes were either removed or sampled. The sensitivity of CT for mediastinal nodes on a per-patient basis was 64%, with a specificity of 62%. The sensitivity of CT for individual nodal stations involved with tumor was only 44%. The presence of obstructive pneumonitis did not appreciably alter the sensitivity of CT, but the specificity was lower (43%). The likelihood of metastases increased with lymph node size; however, seven of 19 (37%) lymph nodes that measured 2-4 cm in short-axis diameter were hyperplastic and did not contain metastases. The relative insensitivity of CT makes formal nodal sampling at the time of mediastinoscopy or thoracotomy essential to detect lymph node metastases.

Cerebral cortical mechanisms of reaching movements.

Abstract: Because reaching movements have a clear objective--to bring the hand to the spatial location of an object--they are well suited to study how the central nervous system plans a purposeful act from sensory input to motor output. Most models of movement planning propose a serial hierarchy of analytic steps. However, the central nervous system is organized into densely interconnected populations of neurons. This paradox between the apparent serial order of central nervous system function and its complex internal organization is strikingly demonstrated by recent behavioral, modeling, and neurophysiological studies of reaching movements.

Gaussian density functional calculations on hydrogen-bonded systems

Abstract: As a test of the applicability of the density functional theory to systems containing hydrogen bonds, linear combination of Gaussian type orbitals-local density calculations have been performed on two intermolecular and two intramolecular hydrogen-bonded systems. A comparison is made of results using the local density approximation (LDA) and those including nonlocal density gradient type corrections, using two different nonlocal functionals. The calculated minimum energy structures for the water dimer and the formamid-water complex are presented

Early disruptive behavior, poor school achievement, delinquent behavior, and delinquent personality: longitudinal analyses

Abstract: Three alternative models concerning the causal links between early disruptive behavior, poor school achievement, and delinquent behavior or antisocial personality were tested with linear structural equation modeling. Subjects were boys and girls followed from first grade to age 14. Disruptive behavior was assessed in Grade 1; school achievement was assessed in Grades 1 and 4; delinquent behavior and antisocial personality were assessed at age 14. With regard to self-reported delinquent behavior at age 14, results indicate that the best model for boys was a direct causal link between Grade 1 disruptive behavior and delinquent behavior. Poor school achievement was not a necessary causal factor. For girls, none of the tested models were a good fit to the delinquent behavior data. As for delinquent personality, results indicate that, for both boys and girls, poor school achievement was a necessary component of the causal path between Grade 1 disruptive behavior and age 14 delinquent personality.

Interleukin 4 protects chronic lymphocytic leukemic B cells from death by apoptosis and upregulates Bcl-2 expression.

Abstract: B chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of slow-dividing and long-lived monoclonal B cells arrested at the intermediate stage of their differentiation. We previously showed that interleukin 4 (IL-4) not only inhibits but also prevents the proliferation of B-CLL cells. We report here that IL-4 protects the B-CLL cells from death by apoptosis (programmed cell death [PCD]). IL-4 inhibits spontaneous and hydrocortisone (HC)-induced PCD of highly purified B cells from 12 unselected CLL patients, as shown by sustained cell viability and lack of DNA fragmentation. IL-1, -2, -3, -5, -6, -7, tumor necrosis factor alpha, and transforming growth factor beta have no protective effect. The in vitro rescue from apoptosis by IL-4 is reflected by an increased expression of Bcl-2 protein, a proto-oncogene directly involved in the prolongation of cell survival in vivo and in vitro. Hence, IL-4-treated B-CLL cells express significantly more Bcl-2 than unstimulated, HC-treated, or fresh B-CLL cells. Furthermore, subcutaneous injection of IL-4 into one CLL patient enhances Bcl-2 protein expression in the leukemic B cells. These data may suggest that IL-4 prevents apoptosis of B-CLL cells using a Bcl-2-dependent pathway. Given our recent observations that fresh T cells from B-CLL patients express IL-4 mRNA, we propose that IL-4 has an essential role in the pathogenesis of CLL disease, by preventing both the death and the proliferation of the malignant B cells.

A Psychophysical Comparison of Sensory and Affective Responses to Four Modalities of Experimental Pain

Abstract: It is generally accepted that the sensory and affective components of pain may be differentially associated with various acute and chronic diseases, and that some treatment regimens are best direct...

Molecular identification of the gene responsible for congenital nephrogenic diabetes insipidus

Abstract: Antidiuretic hormone (arginine vasopressin) binds to and activates V2 receptors in renal collecting tubule cells. Subsequent stimulation of the Gs/adenylyl cyclase system promotes insertion of water pores into the luminal membrane and thereby reabsorption of fluid. In congenital nephrogenic diabetes insipidus (CNDI), an X-linked recessive disorder, the kidney fails to respond to arginine vasopressin. Here we report that an affected male of a family with CNDI has a deletion in the open reading frame of the V2 receptor gene, causing a frame shift and premature termination of translation in the third intracellular loop of the receptor protein. A normal receptor gene was found in the patient's brother. Both the normal and the mutant allele were detected in his mother. A different mutation, causing a codon change in the third transmembrane domain of the V2 receptor, was found in the open reading frame of an affected male but not in the unaffected brother belonging to another family suffering from CNDI.

Testing for a Unit Root in a Time Series With a Changing Mean: Corrections and Extensions

Abstract: (1992). Testing for a Unit Root in a Time Series With a Changing Mean: Corrections and Extensions. Journal of Business & Economic Statistics: Vol. 10, No. 4, pp. 467-470.

Management and Theories of Organizations in the 1990s: Toward a Critical Radical Humanism?

Abstract: The author argues that the present mainstream writings on, and debates about “new” ideas of management and theories of organization, lack adequate theoretical assumptions and background. He proposes that those who question the future and efficiency of Western organizations need to rely more on a radical-humanistic and neo-Marxist conceptualization than on the functionalistic tradition. Therefore, management theorists and practitioners should integrate such a concept in order to better understand how to transform the passive-obedient Taylorist employee into an active-cooperative one. To achieve a truly renewed form of management, researchers must adopt a global view of humankind, in order to give workers a significant measure of control over their own environments and working conditions.

Dressing animated synthetic actors with complex deformable clothes

Abstract: Discusses the use of physics-based models for animating clothes on synthetic actors in motion. In this approach, cloth pieces are first designed with polygonal panels in two dimensions, and are then seamed and attached to the actor's body in three dimensions. After the clothes are created, physical properties are simulated and then clothes are animated according to the actor's motion in a physical environment. The paper describes the physical models used and then addresses several problems encountered. It examines how to constrain the elements of deformable objects which are either seamed together or attached to rigid moving objects. It also describes a new approach to the problem of handling collisions among the cloth elements themselves, or between a cloth element and a rigid object like the human body. Finally, the paper discusses how to reduce the number of parameters for improving the interface between the animator and the physics-based model

Lack of scientific evidence for the treatment of lateral epicondylitis of the elbow. An attempted meta-analysis

Abstract: We have reviewed 185 articles published since 1966 to assess the scientific evidence for methods of treatment for lateral epicondylitis of the elbow. Of the 185 articles, 78 discussed treatment, but since the natural history of the syndrome is uncertain we considered only those series with concurrent control groups. Only 18 of these were randomised and controlled studies. We then graded these papers for scientific validity, using the methods of Chalmers et al (1981). The mean score of the 18 articles was only 33%, with a range from 6% to 73%. A minimum of 70% is required for a valid clinical trial, and we therefore concluded that there was insufficient scientific evidence to support any of the current methods of treatment. There were too many methodological differences to allow a quantitative meta-analysis, but our qualitative review established the importance of the natural evolution of the syndrome and of the placebo effect of all treatments. Properly designed, controlled trials are needed.

Quantitative Distribution of GABA-immunopositive and-immunonegative Neurons and Synapses in the Monkey Striate Cortex (Area 17)

Abstract: The number of GABA-immunoreactive [GABA(+)] neurons and synapses was determined in functionally distinct subregions delineated as rich and poor in cytochrome oxidase (CO) in the visual cortex of adult macaque monkeys. The average numerical density (number per unit volume, Nv) of GABA(+) neurons and synapses was not significantly different between the CO-rich and -poor regions. Twenty percent of the total number of cortical neurons and 17% of the synapses were GABA(+). On average, each visual cortical neuron receives 3900 synapses, 660 of them being GABA(+). The latter were distributed on the target cell in a pattern that predicts the site of GABA influences in cortex. The major targets of GABA(+) synapses were dendritic shafts, comprising nearly two-thirds of the postsynaptic elements. About every fourth and every eighth GABA(+) synapse was devoted to dendritic spines and to neuronal somata, respectively. Axon initial segments, although the exclusive targets of GABA(+) cells, comprise less than 0.1% of structures postsynaptic to GABA(+) boutons. From this distribution, we estimate that in each cubic millimeter of striate cortex there were about 20 million GABA(+) synapses on dendritic spines, 47 million on dendritic trunks, 9 million on somata, and fewer than 0.1 million on axon initial segments. The sites of influences of GABA-immunonegative [GABA(-)] synapses were different in that they target mainly dendritic spines and dendritic trunks. About two-thirds of GABA(-) synapses were on dendritic spines, and the remainder were devoted to dendritic trunks. Only a minute fraction innervate somata. We estimate that in 1 mm3 of striate cortex there were about 235 million GABA(-) synapses on spines, 133 million on dendrites, and about 2 million on somata. The proportions of GABA(+) neurons and synapses and their target distribution did not appreciably differ from those of the visual cortex of the cat even though the numerical density of neurons was 2.5 times higher in the monkey.

The detector simulation program for the OPAL experiment at LEP

Abstract: The Monte Carlo program for the OPAL experiment at the LEP ee collider is described. This program is based on the GEANT simulation package. The general organization of the program is outlined, and a description is given of the techniques used for simulating the various subdetectors of OPAL. The performance of the program is illustrated by comparisons with recent data recorded by OPAL at LEP. (Submitted to Nucl. Instr. and Meth.) School of Physics and Space Research, University of Birmingham, Birmingham, B15 2TT, UK Dipartimento di Fisica dell' Universit a di Bologna and INFN, Bologna, 40126, Italy CNAF-INFN, Bologna, Italy Physikalisches Institut, Universitat Bonn, D-5300 Bonn 1, FRG Department of Physics, University of California, Riverside, CA 92521 USA Cavendish Laboratory, Cambridge, CB3 0HE, UK Carleton University, Dept of Physics, Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada Centre for Research in Particle Physics, Carleton University, Ottawa, Ontario K1S 5B6, Canada CERN, European Organisation for Particle Physics, 1211 Geneva 23, Switzerland Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago Illinois 60637, USA Fakult at f ur Physik, Albert Ludwigs Universitat, D-7800 Freiburg, FRG Universitat Hamburg/DESY, II Inst. f ur Experimental Physik, 2000 Hamburg 52, FRG Physikalisches Institut, Universitat Heidelberg, Heidelberg, FRG Queen Mary and West eld College, University of London, London, E1 4NS, UK University College London, London, WC1E 6BT, UK Department of Physics, Schuster Laboratory, The University, Manchester, M13 9PL, UK Department of Physics and Astronomy, University of Maryland, College Park, Maryland 20742, USA Laboratoire de Physique Nucl eaire, Universit e de Montr eal, Montr eal, Quebec, H3C 3J7, Canada Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK DPhPE, CEN Saclay, F-91191 Gif-sur-Yvette, France International Centre for Elementary Particle Physics, University of Tokyo, Tokyo 113, Japan Brunel University, Uxbridge, Middlesex, UB8 3PH UK Nuclear Physics Department, Weizmann Institute of Science, Rehovot, 76100, Israel Present address: EPFL, Lausanne, Switzerland Present address: Applied Silicon Inc, Ottawa, Canada Present address: Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK On leave from Birmingham University, Birmingham B15 2TT, UK Present address: Culham Laboratory, Culham, Oxfordshire, UK Present address: Meiji Gakuin University, Yokohama 244, Japan

Distribution and regulation of the prohormone convertases PC1 and PC2 in the rat pituitary.

Abstract: PC1 and PC2 are enzymes involved in the activation of prohormones via the cleavage of pairs of basic amino acids. The expression levels of each of these enzymes were evaluated in the rat anterior and neurointermediate pituitary lobes by in situ hybridization and Northern gel analysis and after various pharmacological manipulations. All intermediate lobe melanotrophs expressed high levels of PC2 mRNA and lower levels of PC1 mRNA. PC1 mRNA was highly expressed throughout the anterior lobe; however, appreciable PC2 mRNA levels were also found. Based on colocalization studies, anterior lobe corticotrophs were found to express PC1 mRNA, but very little PC2 mRNA. Neurointermediate lobe levels of PC1, PC2, and POMC mRNA increased 2- to 6-fold in rats treated with haloperidol, while they decreased to 10-25% of their control values after bromocriptine treatment. These results indicate that in the intermediate lobe, dopamine is involved in the regulation of PC1 and PC2. In the anterior lobe, haloperidol had a strong effect on PC2 mRNA, increasing its levels by 8- to 12-fold compared to the control value, while PC1 mRNA was unaffected. Both PC1 and PC2 mRNA levels were increased 5- to 9-fold in animals made hypothyroid by treatment with 6-n-propyl-2-thiouracil. Adrenalectomy had no significant effect on anterior lobe PC1 mRNA levels. However, both PC1 and PC2 mRNA levels were responsive to dexamethasone treatment in the AtT-20 cell lines. Our results indicate that dopamine, thyroid hormones, and corticosteroids are involved in PC1 and/or PC2 gene expression. These data are also consistent with the role of PC1 and PC2 as prohormone-processing enzymes.

Corporate codes of ethics and sales force behavior: A case study

Abstract: A growing public concern regarding ethical business conduct has stimulated marketing research in the ethics area. This study is the first empirical research to investigate the relationship between a code of ethics and sales force behavior. The findings present preliminary evidence that a well communicated code of ethics may be related to ethical sales force behavior. Furthermore, it appears that a sales force that is employed in such an environment can be profiled as being relatively high in job performance and receiving equally high satisfaction from their positions. Suggestions are made for future research and recommendations are offered for marketing practitioners.