Showing papers by "Saint Mary's University published in 1997"
769 citations
TL;DR: Parasites have the capacity to regulate host populations and may be important determinants of community structure, yet they are usually neglected in studies of food webs as discussed by the authors, yet they can provide much of the information on host biology, such as diet and migration, that is necessary to construct accurate webs.
Abstract: Parasites have the capacity to regulate host populations and may be important determinants of community structure, yet they are usually neglected in studies of food webs. Parasites can provide much of the information on host biology, such as diet and migration, that is necessary to construct accurate webs. Because many parasites have complex life cycles that involve several different hosts, and often depend on trophic interactions for transmission, parasites provide complementary views of web structure and dynamics. Incorporation of parasites in food webs can substantially after baste web properties, Including connectance, chain length and proportions of top and basal species, and can allow the testing of specific hypotheses related to food-web dynamics.
366 citations
TL;DR: In this paper, the authors examined the impact of buyer dependence on opportunism against the supplier and found that dependence and opportunism will be positively related under low relational norms, and negatively related under high relational norms.
Abstract: The impact of buyer dependence on opportunism against the supplier is examined in this research. Extant literature provides support for both a positive and an inverse relationship between these constructs. In this research, these competing predictions are subsumed under a more general model where the effect of dependence on opportunism is moderated by the level of relational norms present in the buyer–supplier relationship. Results of an experiment with purchasing managers and one replication provide support for the hypotheses that (a) dependence and opportunism will be positively related under low relational norms, and (b) dependence and opportunism will be inversely related under high relational norms. © 1997 John Wiley & Sons, Inc.
185 citations
TL;DR: The insurrection of indigenous peasants in Chiapas on the first of January in 1994 has had a profound impact on what we could term the sociology of social movements, the way in which movements of resistance and social change are conceived as discussed by the authors.
Abstract: The insurrection of indigenous peasants in Chiapas on the first of January in 1994 has had a profound impact. Not only did it put an end to the ruling class’s — and party’s — illusion of social peace and stability, and brought on centre-stage the long and hard struggles of indigenous peoples in Mexico and elsewhere, but it had a significant impact on what we could term the sociology of social movements — the way in which movements of resistance and social change are conceived. In the immediate context, the uprising seriously undermined and tarnished the glow that surrounded the government’s neoliberal policies of structural adjustment which just a month earlier had been lauded by president Clinton at a summit of Latin American heads of state as a model for other governments in the region to follow. In the same context, it raised serious questions about the feasibility of armed struggle, a tactic that had all but been abandoned by the Left as a result of the repeated failures and the destruction of the many organizations that had taken up arms in the 1960s and 1970s.
107 citations
105 citations
TL;DR: In this article, the structure of the deep interior of a variety of standard and nonstandard solar models constrained by the low-l p-mode oscillation data from GONG is presented.
Abstract: The structure of the deep interior of a variety of standard and nonstandard solar models constrained by the low-l p-mode oscillation data from GONG are presented. For standard models, we show that the effects of both helium and heavy-element diffusion must be included in order to find simultaneous agreement with both the p-mode spectrum and the observed value of (Z/X)☉. Related to this conclusion, we find that the average interior heavy-element abundance is greater than the observed surface abundance in models whose small spacings, which are derived from the p-mode oscillation spectra, best match the observations. The high-quality data from the Global Oscillation Network Group (GONG) now permit a precise determination of the seismic age of the Sun. The best agreement with the calculated oscillation spectra is achieved for 4.5 ± 0.1 Gyr, an age closely consistent with the age of the Sun inferred from meteorites, i.e., 4.53 ± 0.04 Gyr. This result lends strong support to the standard assumption of the theory of stellar evolution. With regard to the nonstandard solar models, we set limits on the extent to which the nonstandard assumptions can be applied to the model while still being consistent with the observed p-modes. The nonstandard assumptions investigated here are: forced mixing in the core, forced mixing in a shell surrounding the core, and near-zero heavy-element abundance in the core. These assumptions were selected because at one time or another they have all been proposed to reduce the neutrino flux of the solar model, thereby bringing the flux of the model more in line with the observed flux. All nonstandard models include helium and heavy element diffusion. We confirm, now using the latest solar model physics, that these nonstandard assumptions, when capable of reducing significantly the solar neutrino flux, perturb the interior structure too much to be consistent with p-mode observations. In addition, we set strict limits on the extent to which these nonstandard assumptions are tolerated by the current p-mode observations. For example, we show that the p-mode small spacings are incompatible with a low-Z core larger than 0.06 M☉ in the Sun. And we show that if the Sun's core is chemically mixed, the extent of the mixed core cannot exceed 0.02 M☉. The seismic data are also incompatible with extensive rapid mixing of 4He in the solar envelope. This, we believe, also argues against the possibility of slow mixing of 3He occurring in a shell, as was recently proposed by Cumming and Haxton to lower the 7Be/8B neutrino flux ratio. But we note that the occurrence of some mixing of 3He and other trace elements and isotopes in the region of the solar interior where the initial 4He abundance is nearly uniform (which could not at this point be detected by seismology) might modify the calculated neutrino fluxes.
85 citations
TL;DR: In this article, the authors investigated the extent to which condominium apartment prices are set in an efficient asset market and found that on average, ex post house price changes move in a direction opposite to their rational expectation.
Abstract: This paper investigates the extent to which condominium apartment prices are set in an efficient asset market. Unlike previous work that focuses on the time-series properties of measures of excess returns, the analysis is framed in terms of the changes in observable house prices over time. More precisely, the paper develops and applies a test of the joint null hypothesis of rational expectations, perfect markets, and no risk premium in the Vancouver condominium apartment market. The empirical results provide significant evidence against the joint null hypothesis. On average, ex post house price changes move in a direction opposite to their rational expectation. This approach offers a methodological advantage over the standard efficiency literature and is shown to provide a more powerful test of market efficiency than conventional return regressions. Another contribution of the paper is to characterize the time-series properties of deviations of condominium prices from those predicted by the risk-neutral rational expectations model, using cointegration and random coefficients techniques. Deviations in house price changes from their (risk-neutral) rational expectations are time varying, stationary, and related to the stage of the real estate price cycle.
79 citations
TL;DR: In this article, the ages of the Pinware terrane and adjacent areas in the Grenville Province in southeast Labrador have been investigated and it was inferred that cooling occurred 30 million years sooner than near its northwest margin.
75 citations
TL;DR: In this paper, the authors show that most of these volcanic rocks are bimodal within-plate suites and that the source of the Palaeozoic felsic volcanic rocks is isotopically indistinguishable beneath southern and northern Nova Scotia and did not substantially change with time.
Abstract: Palaeozoic volcanism in the Avalon Terrane of northern Nova Scotia occurred during three time intervals: Cambrian-early Ordovician, late Ordovician-early Silurian and middle-late Devonian. In the Meguma Terrane of southern Nova Scotia, Palaeozoic volcanism is limited to the middle Ordovician. Geochemical data show that most of these volcanic rocks are bimodal, within-plate suites. Initial e Nd signa- tures range from +5.4 to -1.9 in the rhyolites and +6.8 to +2.7 in the basalts, a difference attributable to the absence or presence, respectively, of a significant crustal component. The data and regional tectonic settings of the Avalon and Meguma terranes suggest that the volcanism was generated in three different within-plate settings: (1) Cambrian-early Ordovician volcanism related to thermal decay of late Proterozoic arc magma- tism during transtensional deformation; (2) middle Ordovician-early Silurian volcanism during sinistral tele- scoping between Laurentia and Gondwana where extensional bends in the Appalachians produced rifting; and (3) Devonian volcanism resulting from lithospheric delamination during dextral transpression and tele- scoping. In each setting, active faults served as conduits for the magmas. Nd isotopic data indicate that the source of the Palaeozoic felsic volcanic rocks is isotopically indistinguishable beneath southern and northern Nova Scotia and did not substantially change with time. This crustal source appears to have separated from the mantle during the Proterozoic, a conclusion consistent with the hypothesis that the Palaeozoic rocks in Nova Scotia were deposited upon a late Proterozoic oceanic-cratonic volcanic arc terrane. The Nd data, when combined with published faunal, palaeomagnetic and U-Pb isotopic data, suggest that the Avalon Terrane was peripheral to Gondwana off northwestern South America during Neoproterozoic and early Palaeozoic times.
69 citations
TL;DR: In this article, a three-dimensional hydrodynamic simulation of a supersonic jet propagating in an isothermal King atmosphere designed to follow the observed density distribution of the Cygnus A cluster gas is presented.
Abstract: The ROSAT data from the cluster gas of Cygnus A are re-examined in light of a three-dimensional hydrodynamic simulation of a supersonic jet propagating in an isothermal King atmosphere designed to follow the observed density distribution of the Cygnus A cluster gas. In addition to the presence of a non-uniform atmosphere, this simulation departs from previous 3D work in that the X-ray (bremsstrahlung) brightness distribution has been determined from the flow variables as a function of time. This simulation provides compelling evidence for the conclusions reached by Carilli et al. who stated that the major features of the X-ray brightness distribution are manifestations of the expanding lobe and the passage of a bow shock within the atmosphere. Further, this work demonstrates that these X-ray features are as much a function of the observing frequency and bandwidth as they are of the local conditions in the cluster gas of Cygnus A. In addition, new estimates of the Mach number of the jet (M~4) as well as the density and temperature jumps across the bow shock are derived by comparing the simulations with the X-ray data from Cygnus A.
69 citations
TL;DR: In this article, a set of three-dimensional magnetohydrodynamical simulations of supermagnetosonic magnetized jets has been performed, and the effect of jet density on jet dynamics and structure is evaluated.
Abstract: A set of three-dimensional magnetohydrodynamical simulations of supermagnetosonic magnetized jets has been performed. The jets contain an equipartition primarily poloidal magnetic field, and the effect of jet density on jet dynamics and structure is evaluated. The jet is precessed at the origin to break the symmetry and to excite Kelvin-Helmholtz-unstable helical modes. In the linear limit, observed structures are similar in all simulations and can be produced by structures predicted to arise as a result of instability. The amplitude of various unstable modes is evaluated. Most unstable modes do not reach the maximum amplitudes estimated from the linear theory by computing displacement surfaces associated with the modes. Surprisingly, even these large-amplitude distortions are fitted reasonably well by displacement surfaces computed from the linear theory. Large-amplitude helical and elliptical distortions lead to significant differences in the nonlinear development of the jets as a function of the jet density. Jets less dense than the surrounding medium entrain material, lose energy through shock heating, and slow down relatively rapidly once large-amplitude distortions develop as a result of instability. Jets more dense than the surrounding medium lose much less energy as they entrain and accelerate the surrounding medium. The dense jet maintains a high-speed spine that exhibits large-amplitude helical twisting and elliptical distortion over considerable distance without disruption of internal jet structures as happens for the less dense jets. This dense high-speed spine is surrounded by a less dense sheath consisting of slower moving jet fluid and magnetic field mixed with the external medium. Simulated synchrotron intensity and fractional polarization images from these calculations provide a considerably improved connection between simulation results and jet observations than do images made using the fluid variables alone. Intensity structure in the dense jet simulation appears remarkably similar to structure observed in the Cygnus A jet. These simulations suggest that the extended jets in high-power radio sources propagate to such large distances without disruption by entrainment because they are surrounded by a lobe or cocoon whose density is less than the jet density.
TL;DR: In this paper, the central region of the Monoceros R2 molecular cloud has been studied using molecular line maps, maps in continuum emission, and an M-band (4.7 μm) absorption spectrum toward Mon R2 IRS 3.
Abstract: The central region of the Monoceros R2 molecular cloud has been studied using molecular line maps, maps in continuum emission, and an M-band (4.7 μm) absorption spectrum toward Mon R2 IRS 3. Maps were made in the emission lines CO (3-2) H2CO (51,5-41,4), and HCN (4-3), all with a 14'' beam size. CO (2-1) and 13CO (3-2) spectra were obtained at a dozen positions. Maps of continuum emission were made at 1300 μm (25'' resolution), 1100 μm (20'' resolution), 800 μm (14'' resolution), and 450 μm (14'' resolution). The M-band spectrum of IRS 3 has a velocity resolution of 5.2 km s-1 and shows fundamental vibrational band absorption lines of CO and 13CO over a range of rotational states. The CO map has numerous intensity peaks which, if interpreted as clumps, have masses from 0.1 to 3 M☉. The large velocity dispersion of these structures implies that they cannot be gravitationally bound. The brightest CO-emitting gas shows no bipolar distribution with velocity. Diffuse CO-emitting gas with low velocities does have a generally bipolar distribution, but there are no collimated lobes pointing to a particular source. We conclude that the source (or sources) of the very extended Mon R2 outflow is (are) now inactive. The highest velocity gas is found toward the embedded young stellar object IRS 3, suggesting that IRS 3 is the source of a compact outflow, unresolved at our 14'' resolution. The presence of blueshifted CO in the absorption spectrum supports the interpretation of IRS 3 as an outflow source. The H2CO and HCN maps demonstrate that much of the dense gas is distributed within three structures having different velocities. The fundamental band absorption lines of 13CO show two gas temperatures in the line of sight to IRS 3. The colder (45 K) is identified as gas in the clump surrounding IRS 3, which is seen in emission lines of CO, H2CO, and HCN. The warmer (310 K) we interpret as gas very close to IRS 3. From the submillimeter continuum maps we identify 11 clumps whose masses lie in the range 3-10 M☉. A clump that is prominent in the continuum maps but not in the molecular line maps is attributed to heated dust inside the compact H II region, where molecules have been destroyed.
TL;DR: Granitic gneiss in a Miocene extensional core complex on Naxos locally preserves primary igneous textures as mentioned in this paper, including mafic enclaves, in thin section, feldspar phenocrysts contain unoriented accessory mineral inclusions.
Abstract: Granitic gneiss in a Miocene extensional core complex on Naxos locally preserves primary igneous textures. On an outcrop scale, these include mafic enclaves; in thin section, feldspar phenocrysts contain unoriented accessory mineral inclusions. The gneiss is interpreted as having a Hercynian granite protolith. Contrary to previous accounts, migmatites are rare in the gneiss. The granite is geochemically similar to post-collisional extension-related granites and differs from the predominant granodiorites found in the Hercynian basement of northwestern Greece.
An I-type hornblende–biotite granite pluton was emplaced during Miocene extension in western Naxos. It is a typical subduction-related pluton emplaced under conditions of back-arc extension. The pluton is cut by later leucogranite that geochemically resembles the granite dykes that cut the migmatites. In northern Naxos, minor leucogranite intrusions are of two geochemical types. One is everywhere deformed and geochemically resembles the leucogranite that cuts the Western pluton. The other is variably deformed and new geochronology shows that it has an age of 10 Ma. © 1997 John Wiley & Sons, Ltd.
TL;DR: In this article, the reaction between the potassium salts of the hydrotris-pyrazolylborate ligands TpMe'Me and TptBu'Me, and the tris THF adduct of scandium trichloride lead to isolation of the Scandium complexes (TpMe...
Abstract: Reaction between the potassium salts of the hydro-tris-pyrazolylborate ligands TpMe'Me and TptBu'Me and the tris THF adduct of scandium trichloride lead to isolation of the scandium complexes (TpMe...
TL;DR: In this paper, an overview of fisheries in Atlantic Canada and examines in detail the two most important and widespread sectors, groundfish and lobsters, highlighting initiatives undertaken in the wake of the collapse of the groundfish stocks in the early 1990s.
TL;DR: In this paper, high-resolution observations of the 2.6 mm continuum and CO (1-0) line emission associated with the young stellar object DG Tau B were made, and the aperture-synthesis CO map clearly showed that redshifted emission is symmetrically distributed about the DG Tau b optical jet and extends at least 6000 AU to the northwest of the unresolved continuum source.
Abstract: We have made high-resolution (4'') observations of the 2.6 mm continuum and CO (1-0) line emission associated with the young stellar object DG Tau B. The aperture-synthesis CO map clearly shows that redshifted emission is symmetrically distributed about the DG Tau B optical jet and extends at least 6000 AU to the northwest of the unresolved continuum source. By contrast, blueshifted CO emission is confined to a compact region, which is less than 500 AU in radius. Within 1000 AU of the star, the redshifted CO emission is elongated, brightest along its central axis, and unresolved in the transverse direction. Beyond 1000 AU, the flow broadens and begins to bifurcate. The morphology of the CO emission provides compelling evidence that the extended molecular outflow is driven by the highly collimated atomic jet. The spatial correspondence between knots in the optical jet and successive broadenings of the outflow supports the hypothesis that the molecular outflow is produced by the action of multiple working surfaces in a time-varying jet.
TL;DR: Assessment of judge sensitivity to foil, instruction, and presentation biases suggests that judges are somewhat sensitive to lineup suggestiveness but there is room for improvement.
Abstract: The motion-to-suppress safeguard is designed to prevent false eyewitness identifications from leading to wrongful convictions This safeguard is effective only if judges are sensitive to factors that influence lineup suggestiveness The present study assessed judge sensitivity to foil, instruction, and presentation biases Judges (N = 99) read a description of a hypothetical crime, perpetrator, and identification procedure followed by a motion to suppress the identification Judges completed a questionnaire in which they ruled on the motion and rated the lineup's suggestiveness and fairness Foil bias and instruction bias influenced judges' rulings and lineup evaluations as predicted Hypotheses concerning presentation bias were not supported These results suggest that judges are somewhat sensitive to lineup suggestiveness but there is room for improvement
TL;DR: In this article, a variable mixing length parameter was proposed to correct the overestimation of convective efficiency in the calculation of the temperature gradient and the mean structure of the superadiabatic layer.
Abstract: The effect of adjustments to the superadiabatic layer (SAL) in a model of the Sun on the p-mode oscillation frequencies has been studied. Numerical simulations of solar convection by Kim and coworkers have shown that the usual mixing length approximation (MLA) overestimates the convective efficiency in the SAL. To correct for the overestimated convective efficiency in the calculation of the temperature gradient and the mean structure of the SAL, we have adopted a variable mixing length parameter, which decreases as the surface is approached, based on a simple parameterization suggested by the simulations. We find that these changes to the structure of the SAL reduce the discrepancies between observed and calculated oscillation frequencies in the low to intermediate l range.
TL;DR: This article investigated the relationship between labor-management climate and perceptions of productivity, product quality, and customer satisfaction using a regional and national sample of Canadian organizations and a regional sample of local unions.
Abstract: I investigate the relationship between labor-management climate and perceptions of productivity, product!service quality, and customer!client satisfaction using a regional and national sample of Canadian organizations and a regional sample of local unions Overall, the ordered probit results reveal a strong relationship between labor-management climate and measures of organizational performance with a more positive labor-management climate associated with more favorable scores on the performance variables
TL;DR: The Sand Bay gneiss association as discussed by the authors is an allochthonous assemblage of supracrustal rocks in the Central Gneiss Belt of the Grenville Province of Ontario.
TL;DR: In the early 1760s, Worcester porcelain was depleted in Al 2 O 3, K 2 O, and enriched in MgO, CaO, Na 2 O and, to a lesser extent, PbO as mentioned in this paper.
TL;DR: In this paper, the potential for sagging was evaluated using phase diagrams and it was shown that the change to phosphatic recipes after the acquisition of the Chelsea works was due to concerns over kiln losses related to sagging rather than the periodic use of nonrefractory glassy recipes.
TL;DR: In this paper, the author explores various social, ethical, pedagogical, and performance reasons for studying gender at work, and he offers some strategies for inserting gender into the everyday business curriculum.
Abstract: This article aims at developing strategies for teaching gender as a central element in the business curriculum. The author explores various social, ethical, pedagogical, and performance reasons for studying gender at work, and he offers some strategies for inserting gender into the everyday business curriculum. The article also furnishes readers with a list of useful educational sources.
TL;DR: Dimethylphenylsilyllithium undergoes conjugate addition to a variety of α,β-unsaturated enones in the presence of sub-stoichiometric amounts of dimethylzinc.
TL;DR: In this article, the results of Pino (1984) are generalized to the multivariate normal linear regression model Y = Xβ + E, and the effect of transferring the information Y to T = A ′ Y may be analyzed through an associated regression problem which is amenable to solution by two step (or rather two stage) least squares.
TL;DR: In this paper, it was shown that both ground-state and transition-state effects are important in determining the barrier to rotation of the arene ring in organometallic molecules.
TL;DR: In this article, a revised protocol for spores of the myxozoan Henneguya doori that accounted for significant drag effects exerted by the experimental apparatus was applied to eggs of the sealworm, Pseudoterranova decipiens.
Abstract: Settling rates and densities of small bodies can be determined by recording settling rates in fluids of different densities, but similar viscosities, and applying Stoke's law. However, at low Reynolds numbers, drag effects reduce the object's settling rate and must be accounted for in sedimentation experiments. Using a revised protocol for spores of the myxozoan Henneguya doori that accounted for significant drag effects exerted by the experimental apparatus, we improve upon a previously described technique and apply it to eggs of the sealworm, Pseudoterranova decipiens. Sealworm eggs have a density of 1.08 x 10(3) kg/m3 and a characteristic Reynolds number of 6 x 10(-3). Fixed eggs settle in seawater at rate of 1.09 x 10(-4) m/sec, whereas fresh eggs settle at a rate of 1.01 x 10(-4) m/sec. Given reported current speeds on the Scotian Shelf off Nova Scotia, Canada, eggs would be transported approximately 50 km in 100 m of water in 12 days before sedimenting on the bottom. Eggs passed 1 m from the bottom would take about 3 hr to settle, and be transported 0.5 km. The size and density of sealworm eggs, and thus their resulting sedimentation rate, may have adaptive value in that they prevent excessive dispersion in space by strong oceanic currents.
TL;DR: This parasite is unique among known species of Myxobolus in having spores that are lenticular in frontal view, and occupying the Pascagoula River System, Mississippi.
Abstract: Myxobolus mississippiensis n. sp. is described from gill lamellae of the bluegill (Lepomis macrochirus) inhabiting the Pascagoula River System, Mississippi. Fresh spores measure 16.4-18.7 microns long, 3.9-6.2 microns wide, and 4.7-6.2 microns thick. Spore width to length ratio is 1:3.2. Polar capsules are 5.5-7.8 microns long and 1.5-2.3 microns wide, with 9-10 filament coils that when extruded measure 42.1 +/- 4.2 microns. This parasite is unique among known species of Myxobolus in having spores that are lenticular in frontal view.
TL;DR: In this paper, an integer formulation which combines permutation variables with flow variables is presented, and an upper bounding scheme for the number of nodes visited in the final solution is used to reduce the size of the integer program.
Abstract: The selective travelling salesperson problem (STSP) involves determining a tour of maximal value over a set of cities subject to a tour length constraint. The problem has the characteristic that not all cities have to be visited. An integer formulation which combines permutation variables with flow variables is presented. An upper bounding scheme for the number of nodes visited in the final solution is used to reduce the size of the integer programme. The problem is solved using an off-the-shelf mixed-integer solver called CPLEX. Results demonstrating the usefulness of the bound are presented. The methodology is also applied to solve a 15-zone fisheries surveillance problem.