Showing papers by "Université du Québec à Montréal published in 1996"
01 Apr 1996
TL;DR: Traced monoidal categories are introduced, a structure theorem is proved for them, and an example is provided where the structure theorem has application as discussed by the authors. But this is not the case for all categories.
Abstract: Traced monoidal categories are introduced, a structure theorem is proved for them, and an example is provided where the structure theorem has application.
488 citations
15 Jun 1996
TL;DR: A logic, generalising Hennessy?Milner logic, which is characteristic for the generalised notion of bisimulation is presented, which makes possible a uniform definition of bisIMulation across a range of different models for parallel computation presented as categories.
Abstract: An abstract definition of bisimulation is presented It makes possible a uniform definition of bisimulation across a range of different models for parallel computation presented as categories As examples, transition systems, synchronisation trees, transition systems with independence (an abstraction from Petri nets), and labelled event structures are considered On transition systems the abstract definition readily specialises to Milner's strong bisimulation On event structures it explains and leads to a strengthening of the history-preserving bisimulation of Rabinovitch and Traktenbrot and van Glabeek and Goltz A tie-up with open maps in a (pre)topos, as they appear in the work of Joyal and Moerdijk, brings to light a new model, presheaves on categories of pomsets, into which the usual category of labelled event structures embeds fully and faithfully As an indication of its promise, this new presheaf model has “refinement” operators The general approach yields a logic, generalising Hennessy?Milner logic, which is characteristic for the generalised notion of bisimulation
290 citations
Journal Article•
TL;DR: In this article, the authors present theoretical tools that can be used to undertake a critical analysis of these constructs, including environmental education in the broader scope of an education for the development of responsible societies.
Abstract: According to UNESCO's recent documents, sustainable development is the "ultimate goal of the Man-environment relationship"; thus, the whole educational process should be "reshaped for sustainable development." In view of the extreme importance of their educational impact, such statements need to be discussed. To which conception of environment, of education and of sustainable development does the concept of environmental education for sustainable development refer? This article presents theoretical tools that can be used to undertake a critical analysis of these constructs. Finally, the idea of including environmental education in the broader scope of an education for the development of responsible societies is considered.
284 citations
TL;DR: In this paper, a series of dialysis experiments was performed to study the relative importance of substrate limitation and grazing in controlling the proportion of active cells of coastal marine bacterioplankton.
Abstract: A series of dialysis experiments was performed to study the relative importance of substrate limitation and grazing in controlling the proportion of active cells of coastal marine bacterioplankton. The grazer community was manipulated by filling dialysis bags with unfiltered water and water serially passed through 150-, 40-, and O.p Ducklow and Carlson 1992). This pattern has prompted speculation that bacterial growth and abundance must be tightly regulated across aquatic systems and confined within a relatively narrow range by a combination of resource limitation and grazing (Sanders et al. 1992; Wright 1988). One issue that is seldom incorporated into models of microbial food webs is the varying proportion of metabolically active and inactive cells. In
254 citations
01 Jun 1996
TL;DR: In this paper, the authors used laser ablation-ICPMS and isotope dilution to obtain more than 400 detrital zircons from the Quadrilatero Ferrifero area of the South American continent.
Abstract: The Sao Francisco shield is one of the major cratonic units forming the backbone of the South American continent. The Quadrilatero Ferrifero area, in the south of the shield, is underlain by three major units: granitic-gneissic terrains with a minimum age of 2860 Ma; the Rio das Velhas greenstone belt, emplaced at 2772–2780 Ma; and the Minas Supergroup-Itacolomi Group Paleoproterozoic sedimentary sequences. The 207 Pb 206 Pb and UPb ages of more than 400 detrital zircons obtained by Laser ablation-ICPMS and isotope dilution lead to the following conclusions: (1) the Rio das Velhas greenstone belt contains exclusively cratogenic sediments and developed on, or proximal to, old, evolved continental crust with a minimum age of ca. 2.85 Ga; (2) the lower detrital sequence of the Minas Supergroup was supplied with sediments derived from both the granite-greenstone terrain and the surrounding older crust; (3) the upper unit of the Minas Supergroup (Sabara Formation) contains 2125 Ma zircon and the overlying Itacolomi Group contain zircons with minimum ages of ca. 2.06 Ga, identical to the ages of regional metamorphism. Together with other considerations, these ages lead to the novel proposal that the tectogenic sedimentation represented by these units occurred in a foreland basin of the Transamazonian orogen. Basin evolution was closely associated with the tectonic development of the orogen and uplift of basement complexes between 2125 Ma and 2030 Ma. The scarcity of 2.6-2.4 Ga zircons in the Proterozoic units of the Quadrilatero Ferrifero confirms previous results for the Sao Francisco shield and is symptomatic of the absence of magmatic-metamorphic activity in that period of time.
238 citations
TL;DR: The Ribeira belt in southeastern Brazil was generated during the Brazilian Orogeny (∼ 700-450 Ma) as discussed by the authors, which is characterized by a series of northwest-vergent crustal-scale thrust stacks emplaced under amphibolite-grade conditions.
225 citations
TL;DR: In this article, the rank-generating function of a graded poset was generalized to the Hopf algebra of quasi-symmetric functions, which is a Hopf algebras of hierarchical simplicial complexes.
219 citations
TL;DR: Panic disorder is a significantly distressful condition highly prevalent in emergency department chest pain patients that is rarely recognized by physicians and may lead to mismanagement of a significant group of distressed patients with or without coronary artery disease.
217 citations
TL;DR: There is a continuum in the δ 13 C differences between POM and zooplankton from open ocean to coastal areas and estuaries and that a similar pattern occurs from unproductive to highly productive lakes, which suggest systematic differences in organic carbon flow pathways among aquatic ecosystems.
Abstract: Measurements of plankton δ 13 C from 28 temperate lakes show that zooplankton are depleted in 13 C relative to smaller planktonic size fractions. A broad literature survey indicates that this is a general pattern in lakes but not in marine and estuarine plankton communities, where zooplankton are generally enriched in 13 C relative to particulate organic matter (POM) or micro-plankton. Marine plankton thus conform to the assumptions that pelagic food webs are essentially driven by phytoplankton and that POM or small planktonic size classes largely reflect algal carbon, which is transferred to zooplankton with a slight enrichment in 13 C. The plankton of lakes and possibly of estuaries, however, do not conform to this expectation. We show that there is a continuum in the δ 13 C differences between POM and zooplankton from open ocean to coastal areas and estuaries and that a similar pattern occurs from unproductive to highly productive lakes. These differences probably reflect both the degree in POM dilution by nonalgal sources of organic carbon and depth-related changes in the isotopic signature of phytoplankton in lakes and suggest systematic differences in organic carbon flow pathways among aquatic ecosystems.
190 citations
TL;DR: The rate of the decline A along the harvest gradient was faster for wild leek than for ginseng and varied with harvesting strategies, and the minimum viable population size was estimated at 170 plants.
Abstract: Many populations of threatened American ginseng (Panax quinquefolium) and vulnerable wild leek (Allium tricoccum) have declined and gone extinct because of overharvesting in Canada. We assessed the impact of harvesting on populations of these species in stochastically varying environments and estimated their extinction thresholds and minimum viable populations. With both species we used four transition ma- trices taken from the literature in stochastic population projections under various harvesting regimes. For American gingseng the mean population growth rate (A) declined with increasing harvesting rate (h) accord- ing to the number of years between harvests (tr), as -0.54 h tr0-( 909. When plants with more than two leaves are harvested every 5 years, a harvest rate of approximately 30% was sufficient to bring the A below the equi- librium value of 1.0. Extinction thresholds, the minimum number of plants needed to rebuild a population, varied from 30 to 90 plants, and the minimum viable population size was estimated at 170 plants. Only a dozen populations known in Canada exceed 170 plants, so most populations could not support any harvest- ing without serious threats to their long-term persistence. For wild leek, two harvesting strategies were identi- fied from confiscated, illegal harvests from Gatineau Park (Quebec): (1) "cboosy" harvesters collect fewer but larger bulbs, and (2) "busy" harvesters collect numerous but smaller bulbs. These data allowed simulations of more-realistic harvesting strategies. The rate of the decline A along the harvest gradient was faster for wild leek than for ginseng and varied with harvesting strategies. At harvesting rates between I and 8% the proba- bility that A falls below the equilibrium value was less than 5%. The extinction threshold of wild leek was esti- mated at 140-480 plants and the minimum viable population at 300-1030 plants, according to the threshold
168 citations
TL;DR: Results obtained by Western blotting analyses using purified virus and E. coli-expressed ORFs 5 to 7 gene products suggested that antibodies directed against the envelope E protein appear by day 7 p.i., whereas antibodies directedagainst the nucleocapsid N and membrane M proteins can only be detected by the end of the second week of PRRSV infection.
Abstract: The kinetics of appearance of antibodies directed to the major structural proteins N, M and E of porcine reproductive and respiratory syndrome virus (PRRSV) was followed in pigs naturally- and experimentally-exposed to the virus. Specific IgM antibody titers were first detected by indirect immunofluorescence (IIF) at the end of the first week of PRRSV infection, peaked by day 14 to 21 post-inoculation (p.i.), then rapidly decreased to undetectable levels by day 35 to 42 p.i. On the other hand, specific IgG antibody titers peaked by day 21 to 28 p.i. and remained unchanged to the end of the 6- or 9-week observation period; in addition, a persistent viremia was observed. Virus neutralizing (VN) antibody titers >8 were not detected until 3 to 4 weeks p.i. Taken together, the results obtained by Western blotting analyses using purified virus andE. coli-expressed ORFs 5 to 7 gene products, suggested that antibodies directed against the envelope E protein appear by day 7 p.i., whereas antibodies directed against the nucleocapsid N and membrane M proteins can only be detected by the end of the second week p.i. No correlation could be demonstrated between VN and IIF antibody titers, viremia, and viral protein specificities of circulating antibodies at various times p.i.
TL;DR: In this article, three Archaean gneissic complexes (Bonfim, Belo Horizonte and Campo Belo) in the southern part of the Sao Francisco craton were studied by means of UPb (zircon and titanite, monazite) and SmNd, RbSr and Pb-Pb(whole rock) methods.
TL;DR: This paper investigated the feasibility of this triggering mechanism by reconstructing sea-surface temperature, salinity and sea-ice cover records for the outlet of the Gulf of St Lawrence into the North Atlantic Ocean.
Abstract: THE cause of the Younger Dryas cold event, which interrupted the last deglaciation, is still a matter of debate1. A prevalent hypothesis, proposed by Broecker et al.2 is that the abrupt climate change was driven by a decrease in the rate of North Atlantic Deep Water production, triggered by a sudden dilution of North Atlantic surface water in response to the diversion of Laurentide icesheet melt water from the Mississippi drainage system to that of the St Lawrence river. Here we investigate the feasibility of this triggering mechanism by reconstructing sea-surface temperature, salinity and sea-ice cover records for the outlet of the Gulf of St Lawrence into the North Atlantic Ocean. These reconstructions—based on dinoflagellate-cyst assemblages3,4 in sediment cores from the region—show reduced meltwater runoff, low temperatures and extensive sea-ice cover during the Younger Dryas, dated here between 10,800 and 10,300 BP. Meltwater pulses did occur before and after the Younger Dryas event: as early as 11,700 BP, during the development of the Champlain Sea in the St Lawrence Lowland, and afterwards, until ~ 10,100 BP. At the resolution of our salinity proxy (0.7‰), the meltwater pulses preceding the Younger Dryas did not affect sea-surface salinity off the shelf break. These constraint on the meltwater outflow through the St Lawrence drainage system do not support the triggering mechanism of the Broecker et al. hypothesis2, unless the North Atlantic thermohaline circulation is more sensitive to small salinity changes than most models suggest23.
TL;DR: A close association between the point of vernalization saturation and the start of a decline in the Wcs120 gene-family mRNA level and protein accumulation in plants maintained at 4°C indicated that vernAlization genes have a regulatory influence over low-temperature gene expression in winter cereals.
Abstract: Low temperature is one of the primary stresses limiting the growth and productivity of wheat (Triticum aestivum L.) and rye (Secale cereale L.). Winter cereals low-temperature-acclimate when exposed to temperatures colder than 10°C. However, they gradually lose their ability to tolerate below-freezing temperatures when they are maintained for long periods of time in the optimum range for low-temperature acclimation. The overwinter decline in low-temperature response has been attributed to an inability of cereals to maintain low-temperature-tolerance genes in an up-regulated state once vernalization saturation has been achieved. In the present study, the low-temperature-induced Wcs120 gene family was used to investigate the relationship between low-temperature gene expression and vernalization response at the molecular level in wheat and rye. The level and duration of gene expression determined the degree of low-temperature tolerance, and the vernalization genes were identified as the key factor responsible for the duration of expression of low-temperature-induced genes. Spring-habit cultivars that did not have a vernalization response were unable to maintain low-temperature-induced genes in an up-regulated condition when exposed to 4°C. Consequently, they were unable to achieve the same levels of low-temperature tolerance as winter-habit cultivars. A close association between the point of vernalization saturation and the start of a decline in the Wcs120 gene-family mRNA level and protein accumulation in plants maintained at 4°C indicated that vernalization genes have a regulatory influence over low-temperature gene expression in winter cereals.
TL;DR: Foraminiferal data from two sites, 6 km apart, on the shores of an inlet near Tofino on the west coast of Vancouver Island, British Columbia, allow estimates to be made of the amount of coseismic subsidence during a large earthquake 100-400 years ago as mentioned in this paper.
TL;DR: It is suggested that drawing deficiencies in AD often reflect impairments in conceptualization and semantic knowledge and that such losses may prove useful in predicting the disease's rate of progression.
TL;DR: In this paper, the relative contribution of asymmetries in prior experience, size, and prior residency to the determination of dyadic dominance between unacquainted individuals was examined using pairs of green swordtail fish, Xiphophorus helleri.
Abstract: The relative contribution of asymmetries in prior experience, size, and prior residency to the determination of dyadic dominance between unacquainted individuals was examined using pairs of green swordtail fish, Xiphophorus helleri. Four types of encounters were staged between an intruder and a smaller resident: (1) both had experienced prior victory; (2) both had experienced prior defeat; (3) the intruder had experienced prior victory and the resident prior defeat; and (4) the intruder had experienced prior defeat and the resident prior victory. In a fifth condition in which two intruders met, one was a prior subordinate and the other a prior dominant smaller in size than its opponent. In all these encounters, the superiority in lateral surface of one fish varied between 0 to 30% over that of its opponent. Results showed that (1) when size differences between contestants were within the range of 0-10% and there was an asymmetry in prior social experience, conflicts were essentially resolved according to prior experience with prior winners systematically defeating prior losers; (2) prior residency of 3 hours was an advantage only when both opponents had experienced prior defeat before meeting and when size asymmetries were small (e.g. <20%). It was not an advantage between prior winners or between a prior winner and a prior loser; (3) when large size asymmetries existed (e.g. 20-30%), size uniquely determined dominance outcome and nullified other advantages or disadvantages due to prior social experience and prior residency; and (4) at intermediate levels of size asymmetries (e.g. 10-20%), size partially cancelled any advantage due to a prior victory, and gradually beacme the most important factor in accounting for victories.
TL;DR: The Campo de Tiro type-section for the Tyrrhenian ecostratigraphic beds of the Balearic Islands shows four indurated littoral conglomerates and beach-rocks, unconformably superimposed as mentioned in this paper.
TL;DR: In this paper, the authors considered the problem of finite Dehn surgery on a 3-manifold and showed that there are at most 6 finite and cyclic surgeries on K of maximal mutual distance 5.
Abstract: Let K be a knot with a closed tubular neighbourhood N(K) in a connected orientable closed 3-manifold W , such that the exterior of K, M = W − intN(K), is irreducible. We consider the problem of which Dehn surgeries on K, or equivalently, which Dehn fillings on M , can produce 3-manifolds with finite fundamental group. For convenience, a surgery is called a G-surgery if the resultant 3-manifold has fundamental group G. If G is cyclic or finite, the surgery is also called a cyclic surgery or a finite surgery. Similar terminology will be used for Dehn fillings. The manifold obtained by the Dehn filling on M along ∂M with slope r is denoted by M(r). Let ∆(r1, r2) denote the minimal geometric intersection number (the distance) between two slopes r1 and r2 on ∂M . According to [T1], M belongs to one of the following three mutually exclusive categories: (I) M is a Seifert fibred space admitting no essential torus. (II) M is a hyperbolic manifold (i.e. intM admits a complete hyperbolic metric of finite volume). (III) M contains an essential torus. It is a remarkable result, the so-called cyclic surgery theorem [CGLS], that if M is not Seifert fibred, then all cyclic surgery slopes of K have mutual distance no larger than 1, and consequently, there are at most 3 cyclic surgeries on K. In this paper, we consider finite Dehn surgery on K and we prove, for instance, that if M is not a manifold of type (I) and is not a union along a torus of the twisted I-bundle over the Klein bottle and a cabled space, then there are at most 6 finite and cyclic surgeries on K of maximal mutual distance 5. Henceforth, we shall use finite/cyclic to mean either finite or (infinite) cyclic. It turns out to be convenient to consider the three cases mentioned above separately. In case (I) it is well-known that one can completely classify the finite/cyclic surgeries on K. Considering the torus knots for instance, one sees that there exist infinitely many knots whose exteriors are of type (I), each of which admit an infinity of distinct finite (cyclic or non-cyclic) surgery slopes. Our contributions deal with the cases (II) and (III). For the former we obtain
TL;DR: It was demonstrated using seven different drugs and one protein that the mechanism of release by the hydrogel matrix was a Fickian diffusion-controlled process, and it is believed that this family of BSA-PEG hydrogels could be useful for the preparation of controlled release devices in the field of wound dressing.
TL;DR: Following a subacute exposure (1 week), plasma cortisol levels of the exposed fish increased compared with controls, plasma T4 levels decreased and plasma T3 levels remained stable, and no effect on weight gain was found.
TL;DR: In this article, it was shown that up to diffeomorphism there is at most one symplectic form on an oriented S2-bundle over a compact Riemann surface.
Abstract: Let M be an oriented S2-bundle over a compact Riemann surface Σ. We show that up to diffeomorphism there is at most one symplectic form on M in each cohomology class. Since the possible cohomology classes of symplectic forms on M are known, this completes the classification of symplectic forms on these manifolds. Our proof relies on a simplification of our previous arguments and on the equivalence between Gromov and Seiberg-Witten invariants that we apply twice.
TL;DR: In this paper, the authors compared the techniques used by six expert handlers and six novices during a free handling task, where each subject had to transfer three sets of 16 boxes from a platform to a four-wheel cart.
TL;DR: It is indicated that both mercurial compounds stimulate the pituitary-interrenal and the pituitsary-thyroid axis and modify the carbohydrate metabolism in juvenile rainbow trout, and that the organic mercury CH3Hg+ is a more potent chemical stressor than the inorganic Hg2+.
TL;DR: In this article, the authors attempted to derive a definition of sportsmanship by applying premises from social psychological theories and research, and found that sportsmanship meanings and labels attached to given behaviors are learned through interpersonal interactions with various sport participants and that eventually a consensual agreement develops regarding the nature of sportmanship.
Abstract: One major problem with research conducted on sportsmanship is the absence of an accepted definition. The purpose of this study was to attempt to derive a definition of sportsmanship by applying premises from social psychological theories and research. A major assumption of this perspective is that sportsmanship meanings and labels attached to given behaviors are learned through interpersonal interactions with various sport participants and that eventually a consensual agreement develops regarding the nature of sportsmanship. It thus follows that a meaningful definition of sportsmanship should be obtained through the athletes themselves. In this study, 1056 male and female athletes completed a questionnaire which contained various items pertaining to sportsmanship. Results from a factor analysis revealed the presence of 5 factors corresponding to the respect and concern for: a) one's full commitment toward sport participation, b) the rules and officials. c) social conventions, d) the opponent, as ...
TL;DR: In this paper, a comparison of marine, lacustrine, and terrestrial records from twenty-four sites suggests the existence of a Younger Dryas-type climate oscillation just prior to the Oxygen Isotope Stage 6/5e boundary.
TL;DR: Elevated viral abundance and their erratic distribution in the sediments suggest that viruses might play an important role in sediment microbial dynamics.
Abstract: Viruses were found to be very abundant in the top layer of the sediments of Lac Gilbert, Quebec. Viruses were extracted from the sediments using pyrophosphate buffer, and viruses from the diluted extracts were pelleted onto grids and enumerated using transmission electron microscopy. Viral abundance in the sediments ranged from 6.5 × 108 to 1.83 × 1010 ml−1, which is 10- to 1,000-fold greater than the number observed in the water column. This increase corresponds well with the 100- to 1,000-fold increase in bacterial abundance in the sediments. Viral abundance differed significantly among the surface sediment samples taken at different bottom depths and among samples taken at different depths of the water column. Viral abundance also varied significantly between the oxic and anoxic zones of the water column and the sediments. The virus-to-bacteria ratio varied greatly among the different sediment sites but not among depths in the water column. Viral abundance in the water column was related to bacterial abundance and chlorophyll concentration, whereas viruses in the sediments were most abundant in sediments with high organic matter content. Elevated viral abundance and their erratic distribution in the sediments suggest that viruses might play an important role in sediment microbial dynamics.
TL;DR: It is demonstrated that CsA induces reversible overexpression of PGP in the rat, which may present significant relevance in the design of clinical trials using C'sA as a chemosensitizing agent.
Abstract: To see whether P-glycoprotein (PGP) expressed in renal brush-border membranes (BBM) could interact with compounds known as modulators of multidrug resistance (MDR), photoaffinity-labeling experiments were performed. A 145k-Da protein was photolabeled with [125I] iodoarylazidoprazosin, and this labeling was reduced in the presence of cyclosporin A (CsA) and PSC-833 (PSC). Interaction of CsA with PGP was further investigated by treating rats with daily subcutaneous injections of CsA (10 mg.kg-1.day-1). After this treatment, PGP expression levels were dramatically increased in renal BBM, intestine, liver, and many other tissues except the brain. This induction was a reversible process, since after cessation of CsA administration PGP levels declined to reach values similar to those of the control groups. The increase in PGP expression in the kidney was also detected in photolabeling experiments, suggesting the induction of a functional PGP. A higher dose of CsA (50 mg/kg) given as a bolus injection did not modify PGP expression] in renal BBM. These results demonstrate that CsA induces reversible overexpression of PGP in the rat. This may present significant relevance in the design of clinical trials using CsA as a chemosensitizing agent.
TL;DR: Results suggest that bystanders of conditions E and C1 gained some information on the relationship existing between their prior dominant and the stranger and that they used it coherently, perhaps through transitive inference, thus contributing to the existence of transitive relationships within the triads.
TL;DR: The self-assembly of the building blocks [Cr(bipy)(C2O4)2]- with bivalent metal ions (Ba(II, Mn(II), and Co(II)) led to three completely different structures as mentioned in this paper.
Abstract: The self-assembly of the building blocks [Cr(bipy)(C2O4)2]- with bivalent metal ions (Ba(II), Mn(II), and Co(II)) led to three completely different structures: [BaCr2(bipy)2(C2O4)4(H2O)]n·nH2O (1), [MnCr2(bipy)2(μ-C2O4)4]n (2), and CoCr2(bipy)2(μ-C2O4)2(C2O4)2(H2O)2·H2O (3). The molecular and crystal structures of the three compounds were determined. Crystal 1 is monoclinic, P21/n, with a = 15.949(11) A, b = 13.206(9) A, c = 16.957(12) A, β = 113.39(4)°, and Z = 4. The compound is a scaffolding-like material with a unique three-dimensional structure. Crystal 2 is monoclinic, P21/c, with a = 8.674(4) A, b = 13.416(8) A, c = 27.82(2) A, β = 107.30(4)°, and Z = 4. Its structure reveals a novel heterobimetallic chain with octacoordinated manganese(II) atoms. The geometry of the manganese atoms is described as a flattened square antiprism. The Co compound (3) is monoclinic, C2/c, with a = 20.505(5) A, b = 11.093(3) A, c = 17.346(4) A, β = 125.02(2)°, and Z = 4. Its structure consists of discrete linear {CrCoC...