Showing papers by "Saint Mary's University published in 2004"

Interval Set Clustering of Web Users with Rough K -Means

Abstract: Data collection and analysis in web mining faces certain unique challenges. Due to a variety of reasons inherent in web browsing and web logging, the likelihood of bad or incomplete data is higher than conventional applications. The analytical techniques in web mining need to accommodate such data. Fuzzy and rough sets provide the ability to deal with incomplete and approximate information. Fuzzy set theory has been shown to be useful in three important aspects of web and data mining, namely clustering, association, and sequential analysis. There is increasing interest in research on clustering based on rough set theory. Clustering is an important part of web mining that involves finding natural groupings of web resources or web users. Researchers have pointed out some important differences between clustering in conventional applications and clustering in web mining. For example, the clusters and associations in web mining do not necessarily have crisp boundaries. As a result, researchers have studied the possibility of using fuzzy sets in web mining clustering applications. Recent attempts have used genetic algorithms based on rough set theory for clustering. However, the genetic algorithms based clustering may not be able to handle the large amount of data typical in a web mining application. This paper proposes a variation of the K-means clustering algorithm based on properties of rough sets. The proposed algorithm represents clusters as interval or rough sets. The paper also describes the design of an experiment including data collection and the clustering process. The experiment is used to create interval set representations of clusters of web visitors.

The primordial stakeholder: Advancing the conceptual consideration of stakeholder status for the natural environment

Abstract: This article furthers the argument for a stakeholder theory that integrates into managerial decision-making the relationship between business organizations and the natural environment The authors review the literature on stakeholder theory and the debate over whom or what should count as a stakeholder The authors also critique and expand the stakeholder identification and salience model developed by Mitchell and Wood (1997) by reconceptualizing the stakeholder attributes of power, legitimacy, and urgency, as well as by developing a fourth stakeholder attribute: proximity In this way, the authors provide a stronger basis for arguing for the salience of the natural environment as the primary and primordial stakeholder of the firm

Managing Soil Microorganisms to Improve Productivity of Agro-Ecosystems

Abstract: Historically, agricultural production has relied on practices designed to manage nutrients, water, weeds, and crop diseases. Precision agriculture and integrated pest management programs have gone one step further by recognizing the need to target inputs where they are required in the field. The major objective of these programs has been to minimize adverse environmental impacts of intensive agriculture practices and reduce per unit production costs. This review surveys the literature, examining the manipulation of microbial (primarily bacterial) populations as linked to agricultural production, and discusses new approaches that involve the precision management of microorganisms in the agro-ecosystem. It is proposed that our understanding of plant–soil interactions can be greatly refined through the development of “smart” field technology, where real-time, computer-controlled electronic diagnostic devices can be used to monitor rhizosphere and plant health. We submit that “smart field” generated informati...

A new synthetic model for asymptotic giant branch stars

Abstract: We present a synthetic model for thermally pulsing asymptotic giant branch (TPAGB) evolution constructed by fitting expressions to full evolutionary models in the metallicity range 0.0001 Z 0.02. Our model includes parametrizations of third dredge-up and hot-bottom burning with mass and metallicity. The Large Magellanic Cloud and Small Magellanic Cloud carbon star luminosity functions are used to calibrate third dredge-up. We calculate yields appropriate for galactic chemical evolution models for 1 H, 4 He, 12 C, 13 C, 14 N, 15 N, 16 O and 17 O. The

Predicting openness and commitment to change

Abstract: Developed and tested a model of the change management strategies that predict openness and commitment to a large‐scale organizational change. Based on a sample of 164 employees, a partially‐ and a fully‐mediated model were compared with the former providing the best fit to the data. Communication and job security predicted openness and trust both directly and indirectly, via procedural justice. Participation predicted trust directly and indirectly but predicted openness to change only indirectly (via procedural justice). Turnover intentions were negatively predicted by openness and trust. Finally, turnover intentions predicted neglect. These results highlight the role of procedural justice perceptions in understanding organizational change.

Basic instrumentation for Hall A at Jefferson Lab

Abstract: The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electro-and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. The central components of Hall A are two identical high resolution spectrometers, which allow the vertical drift chambers in the focal plane to provide a momentum resolution of better than 2 x 10(-4). A variety of Cherenkov counters, scintillators and lead-glass calorimeters provide excellent particle identification. The facility has been operated successfully at a luminosity well in excess of 10(38) CM-2 s(-1). The research program is aimed at a variety of subjects, including nucleon structure functions, nucleon form factors and properties of the nuclear medium. (C) 2003 Elsevier B.V. All rights reserved.

Reaction Rate Uncertainties and the Production of 19F in Asymptotic Giant Branch Stars

Abstract: We present nucleosynthesis calculations and the resulting 19F stellar yields for a large set of models with different masses and metallicity. During the asymptotic giant branch (AGB) phase, 19F is produced as a consequence of nucleosynthesis occurring during the convective thermal pulses and also during the interpulse periods if protons from the envelope are partially mixed in the top layers of the He intershell (partial mixing zone). We find that the production of fluorine depends on the temperature of the convective pulses, the amount of primary 12C mixed into the envelope by third dredge-up, and the extent of the partial mixing zone. Then we perform a detailed analysis of the reaction rates involved in the production of 19F and the effects of their uncertainties. We find that the major uncertainties are associated with the 14C(α, γ)18O and 19F(α, p)22Ne reaction rates. For these two reactions we present new estimates of the rates and their uncertainties. In both cases the revised rates are lower than previous estimates. The effect of the inclusion of the partial mixing zone on the production of fluorine strongly depends on the very uncertain 14C(α, γ)18O reaction rate. The importance of the partial mixing zone is reduced when using our estimate for this rate. Overall, rate uncertainties result in uncertainties in the fluorine production of about 50% in stellar models with mass 3 M☉ and of about a factor of 7 in stellar models of mass 5 M☉. This larger effect at high masses is due to the high uncertainties of the 19F(α, p)22Ne reaction rate. Taking into account both the uncertainties related to the partial mixing zone and those related to nuclear reactions, the highest values of 19F enhancements observed in AGB stars are not matched by the models. This is a problem that will have to be revised by providing a better understanding of the formation and nucleosynthesis in the partial mixing zone, as well as in relation to reducing the uncertainties of the 14C(α, γ)18O reaction rate. At the same time, the possible effect of cool bottom processing at the base of the convective envelope should be included in the computation of AGB nucleosynthesis. This process could, in principle, help to match the highest 19F abundances observed by decreasing the C/O ratio at the surface of the star, while leaving the 19F abundance unchanged.

Estimation of missing traffic counts using factor, genetic, neural and regression techniques

Abstract: Analyses from some of the highway agencies show that up to 50% permanent traffic counts (PTCs) have missing values It will be difficult to eliminate such a significant portion of data from traffic analysis Literature review indicates that the limited research uses factor or autoregressive integrated moving average (ARIMA) models for predicting missing values Factor-based models tend to be less accurate ARIMA models only use the historical data In this study, genetically designed neural network and regression models, factor models, and ARIMA models were developed It was found that genetically designed regression models based on data from before and after the failure had the most accurate results Average errors for refined models were lower than 1% and the 95th percentile errors were below 2% for counts with stable patterns Even for counts with relatively unstable patterns, average errors were lower than 3% in most cases

Modelling self-pollution of globular clusters from asymptotic giant branch stars

Abstract: A self-consistent model of the chemical evolution of the globular cluster NGC 6752 is presented to test a popular theory that observed abundance anomalies are due to 'internal pollution' from intermediate-mass asymptotic giant branch stars. We simulated the chemical evolution of the intracluster medium under the assumption that the products of Type II supernovae are completely expelled from the globular cluster, whereas the material ejected from stars with m 7Mis retained, due to their weak stellar winds. By tracing the chemical evolution of the intracluster gas we have tested an internal pollution scenario, in which the Na- and Al-enhanced ejecta from intermediate-mass stars is either accreted on to the surfaces of other stars, or goes toward forming new stars. The observed spread in Na and Al was reproduced, but not the O-Na and Mg-Al anticorrelations. In particular, neither O nor Mg are sufficiently depleted to account for the observations. We predict that the Mg content of Na-rich cluster stars should be overwhelmingly dominated by the 25,26 Mg isotopes, whereas the latest data show only a mild 26 Mg enhancement and no correlation with 25 Mg. Furthermore, stars bearing the imprint of intermediate-mass stellar ejecta are predicted to be strongly enhanced in both C and N, in conflict with the empirical data. We show that the NGC 6752 data are not matched by a model incorporating detailed nucleosynthetic yields from asymptotic giant branch stars. Although these stars do show the hot hydrogen burning that seems to be required to explain the observations, this is accompanied by helium burning, producing primary C, N, Mg and Na (via hot-bottom burning) which do not match the observations. Based on current theories of intermediate-mass stellar nucleosynthesis, we conclude that these stars are not responsible for most of the observed globular cluster abundance anomalies.

Modelling self-pollution of globular clusters from AGB stars

Abstract: A self-consistent model of the chemical evolution of the globular cluster NGC 6752 is presented to test a popular theory that observed abundance anomalies are due to ``internal pollution'' from intermediate mass asymptotic giant branch stars. We simulated the chemical evolution of the intracluster medium under the assumption that the products of Type II SNe are completely expelled from the globular cluster, whereas material ejected from stars with m < 7 M_sun is retained, due to their weak stellar winds. By tracing the chemical evolution of the intracluster gas, we tested an internal pollution scenario in which the Na- and Al-enhanced ejecta from intermediate mass stars is either accreted onto the surfaces of other stars, or goes toward forming new stars. The observed spread in Na and Al was reproduced, but not the O-Na and Mg-Al anticorrelations. In particular, neither O nor Mg are sufficiently depleted to account for the observations. We predict that the Mg content of Na-rich cluster stars should be overwhelmingly dominated by the 25,26Mg isotopes, whereas the latest data shows only a mild 26Mg enhancement and no correlation with 25Mg. Furthermore, stars bearing the imprint of intermediate mass stellar ejecta are predicted to be strongly enhanced in both C and N, in conflict with the empirical data. We find that while standard AGB stellar models do show the hot H burning that seems required to explain the observations, this is accompanied by He burning, producing primary C, N, Mg and Na (via HBB) which do not match the observations. (Abridged)

A putative new endophytic nitrogen-fixing bacterium Pantoea sp. from sugarcane.

Abstract: Aims: To isolate and identify endophytic nitrogen-fixing bacteria in sugarcane growing in Cuba without chemical fertilizers. Methods and Results: Two N2-fixing isolates, 9C and T2, were obtained from surface-sterilized stems and roots, respectively, of sugarcane variety ML3-18. Both isolates showed acetylene reduction and H2 production in nitrogen-free media. Nitrogenase activity measured by H2 production was about 15 times higher for isolate 9C than for T2 or for Gluconoacetobacter diazotrophicus (PAL-5 standard strain, ATCC 49037). The nifH gene segment was amplified from both isolates using specific primers. Classification of both T2 and 9C was made on the basis of morphological, biochemical, PCR tests and 16S rDNA sequence analysis. Conclusions: Isolate 9C was identified as a Pantoea species from its 16S rDNA, but showed considerable differences in physiological properties from previously reported species of this genus. For example, 9C can be cultured over a wide range of temperature, pH and salt concentration, and showed high H2 production (up to 67·7 nmol H2 h−1 1010 cell−1). Isolate T2 was a strain of Gluconacetobacter diazotrophicus. Significance and Impact of the Study: A new N2-fixing endophyte, i.e. Pantoea, able to produce H2 and to grow in a wide range of conditions, was isolated from sugarcane stem tissue and characterized. The strain with these attributes may well be valuable for agriculture.

Strategy as Simulacra? A Radical Reflexive Look at the Discipline and Practice of Strategy*

Abstract: Over the past three decades strategic management has become a crucial aspect of business education and practice. At the core of strategic management – linking technique to worldview – is modelling (e.g. value chain, SWOT analysis) whereby the complex elements of strategic thinking are simplified. This accounts in large part for the apparent popularity of strategic management as complex interrelationships are pursued through relatively simple models. Yet has the field of strategic management realized the third order of simulacra? Is strategic management a model of simulation whereby reality has been replaced by hyperreality? A review of the extant literature on strategy explores the study and practice of strategy as a discourse, engulfed by its own truth effects. An examination of the concepts of reflexivity demonstrates the value of a postmodern radical reflexive account through the application of Baudrillard's (1983, 1988, 1991, 1994) simulation and simulacra. It is through the development of a radical reflexive discourse of strategy as simulacra, this paper critically examines the study and practice of strategy and the lessons we can take from this perspective.

The U-Shaped Investment Curve: Theory and Evidence

Abstract: We analyze how the availability of internal funds affects a firm's investment in the presence of capital market imperfections. Using a model that endogenizes the cost of external funds and allows for negative levels of internal funds, we show that under otherwise standard assumptions, investment is a U-shaped function of internal funds. As internal funds decrease, the cost of maintaining a given investment increases, which makes a smaller investment more attractive. For low internal funds, however, the firm will be induced to invest more, not less: a larger investment generates more revenue, which makes it easier to repay the lender and therefore benefits the firm. We test our theory using an unusually comprehensive data set, and find strong support for our predictions. In particular, we find a negative relation between internal funds and investment for a sizable fraction of firms with low (negative) levels of internal funds. Our results qualify conventional wisdom about the effects of financial constraints on investment behavior, and help to explain seemingly conflicting findings in the empirical literature.

The impact of visit frequency on the relationship between service quality and outpatient satisfaction: a South Korean study.

Abstract: Objective To examine the relative impact of four service quality dimensions on outpatient satisfaction and to test the invariance of the structural relationships between the service quality dimensions and satisfaction across three patient groups of varying numbers of prior visits to the same hospital as outpatients.

Genetically Designed Models for Accurate Imputation of Missing Traffic Counts

Abstract: Highway agencies traditionally have used simple methods to estimate missing values in their data sets since traffic data programs were established in the 1930s. A literature review shows that current practices for imputing traffic data are varied and intuitive. No research has been conducted to assess imputation accuracy. Typical traditional imputation methods used by highway agencies were identified in a study and used to estimate missing hourly volumes for sample traffic counts from Alberta, Canada, to examine their accuracy. It was found that such models usually resulted in large imputation errors. For example, for imputing missing data of a traffic count located on a commuter site, the 95th percentile errors for the traditional methods are usually between 10% and 20%. Advanced models based on genetic algorithms, a time-delay neural network, and locally weighted regression developed in the study show higher accuracy than traditional imputation models. Most of the 95th percentile errors for genetically designed neural network models tested on the same count are below 6%. For genetically designed regression models, the 95th percentile errors are less than 2%. Study results based on the sample traffic counts from different trip pattern groups and functional classes show that underlying traffic patterns have some influence on imputation accuracy. However, genetically designed regression models still can limit the 95th percentile errors to less than 5% in most cases. It is believed that such accurate imputations should be able to supply satisfactory data for decision making at both planning and operation levels.

On the origin of fluorine in the Milky Way

Abstract: The main astrophysical factories of fluorine ( 19 F) are thought to be Type II supernovae, Wolf‐ Rayet stars, and the asymptotic giant branch (AGB) of intermediate-mass stars. We present a model for the chemical evolution of fluorine in the Milky Way using a semi-analytic multizone chemical evolution model. For the first time, we demonstrate quantitatively the impact of fluorine nucleosynthesis in Wolf‐Rayet and AGB stars. The inclusion of these latter two fluorine production sites provides a possible solution to the long-standing discrepancy between model predictions and the fluorine abundances observed in Milky Way giants. Finally, fluorine is discussed as a possible probe of the role of supernovae and intermediate-mass stars in the chemical evolution history of the globular cluster ω Centauri. Ke yw ords: stars: abundances ‐ stars: evolution ‐ galaxies: evolution.

Cyanolichens: their response to pollution and possible management strategies for their conservation in northeastern north america

Abstract: This short review focuses on lichens which have cyanobacteria as their main photosynthetic partner or in localized areas termed cephalodia. Research is cited to show that cyanolichens are very sensitive to gaseous air pollution, to acid rain, and to habitat disturbance. These lichens are worth conserving for their own sake but are also valuable for assessing the status of forests in areas like northeastern North America, where forests cover large tracts of land. The richness of the cyanolichen flora reflects biological diversity in the forests. Cyanolichens fix atmospheric nitrogen, are generally nutrient-rich, and have a diverse associated invertebrate fauna. These invertebrates provide food that sustain both resident and migrating birds. Management strategies that might be used to maintain and ensure the survival of the rich cyanolichen flora of the northeastern U.S. and Atlantic Provinces of Canada are presented and discussed.

Recovery of late-seral vascular plants in a chronosequence of post-clearcut forest stands in coastal Nova Scotia, Canada

Abstract: We investigated the impacts of clearcutting on the ground vegetation of remnant late-successional coastal Acadian forests in southwestern Nova Scotia. Vegetation was sampled in 750 1-m2 quadrats established in 16 stands belonging to different recovery periods since clearcutting (3–54 years) and 9 late-successional forests (100–165 years) with no signs of significant human disturbance. Our objectives were to: i) describe the changes in species richness, diversity, and abundance of ground vegetation after clearcutting; ii) examine the responses of residual species (i.e., late-successional flora) to clearcutting; and iii) determine whether any forest species were restricted to or dependent upon the late-successional stages of stand development for maximal frequency and/or abundance. Although clearcutting had no immediate impact on overall alpha richness or diversity, the richness and diversity of residual plants declined after canopy removal and showed no evidence of recovery over 54 years of secondary succession. Consequently, compositional differences between secondary and late-seral stands persisted for many decades after clearcutting. Several understory herbs (e.g., Coptis trifolia (L.) , Oxalis montana (L.), Monotropa uniflora (L.)) were restricted to or attained their highest frequency and abundance in late-seral forests. These results suggest that the preservation of remnant old stands may be necessary for the maintenance of some residual plants in highly disturbed and fragmented forest landscapes in eastern Canada.

Interval set clustering of web users using modified Kohonen self-organizing maps based on the properties of rough sets

Abstract: Web usage mining involves application of data mining techniques to discover usage patterns from the web data. Clustering is one of the important functions in web usage mining. The likelihood of bad or incomplete web usage data is higher than the conventional applications. The clusters and associations in web usage mining do not necessarily have crisp boundaries. Researchers have studied the possibility of using fuzzy sets in web mining clustering applications. Recent attempts have adapted the K-means clustering algorithm as well as genetic algorithms based on rough sets to find interval sets of clusters. The genetic algorithms based clustering may not be able to handle large amounts of data. The K-means algorithm does not lend itself well to adaptive clustering. This paper proposes an adaptation of Kohonen self-organizing maps based on the properties of rough sets, to find the interval sets of clusters. Experiments are used to create interval set representations of clusters of web visitors on three educational web sites. The proposed approach has wider applications in other areas of web mining as well as data mining.

The Biological Reification of Race

Abstract: A consensus view appears to prevail among academics from diverse disciplines that biological races do not exist, at least in humans, and that race-concepts and race-objects are socially constructed. The consensus view has been challenged recently by Robin O. Andreasen's cladistic account of biological race. This paper argues that from a scientific viewpoint there are methodological, empirical, and conceptual problems with Andreasen's position, and that from a philosophical perspective Andreasen's adherence to rigid dichotomies between science and society, facts and values, nature and culture, and the biological and the social needs to be relinquished. DNA forensics is just one field of research that reveals how race remains both idea and object for human population biologists, an indication that it is premature to accept the existence of a no-race consensus across the disciplines. DNA forensics research also demonstrates ways in which race is reified by scientists by the representation of what is cultural or social as natural or biological, and of what is dynamic, relative, and continuous as static, absolute, and discrete. The philosophical analysis of foundational concepts of human population biology such as population, race, and ethnic group is best served by foregoing traditional objectivist approaches for a critical stance that recognises the inextricability of the biological and the social.

Diffraction-limited bispectrum speckle interferometry of the nuclear region of the Seyfert galaxy NGC 1068 in the H and K' bands

Abstract: We present near-infrared bispectrum speckle interferometry studies of the nuclear region of the Seyfert 2 galaxy NGC 1068. A diffraction-limited K � -band image with 74 mas resolution and the first H-band image with 57 mas resolution were reconstructed from speckle interferograms obtained with the SAO 6 m telescope. The resolved structure consists of a compact core and an extended northern and south-eastern component. The compact core is resolved at all position angles and has a north-western, tail-shaped extension as well as a fainter, south-eastern extension. The K � -band FWHM diameter of this compact core is approximately 18 × 39 mas or 1.3 × 2.8 pc (FWHM of a single-component Gaussian fit; fit range 30-80% of the telescope cut-off frequency; the diameter errors are ±4 mas), and the position angle (PA) of the north-western extension is -16 ± 4 ◦ . If 40% of the flux from the compact Kcore is emission from a point source and 60% from a Gaussian intensity distribution, then a slightly larger FWHM of approximately 26 × 58 mas is obtained for the compact Kcomponent. In the H band, the FWHM diameter of the compact core is approximately 18 × 45 mas (±4 mas), and the PA is -18 ± 4 ◦ . The extended northern component (PA ∼ 0 ◦ ) has an elongated structure with a length of about 400 mas or 29 pc. The extended south-eastern component is fainter than the northern component. The K � -a ndH-band fluxes from the resolved compact core were measured to be 350 ± 90 mJy (i.e., K � ∼ 8.2 m ) and 70 ± 20 mJy (H ∼ 10.4 m ), respectively. The PA of -16 ± 4 ◦ of the compact 18 × 39 mas core is very similar to that of the western wall (PA ∼ -15 ◦ ) of the bright region of the ionization cone. This suggests that the H- and K � -band emission from the compact core is both thermal emission and scattered light from dust near the western wall of a low-density, conical cavity or from the innermost region of a parsec-scale dusty torus that is heated by the central source (the dust sublimation radius of NGC 1068 is approximately 0.1-1 pc). The northern extended 400 mas structure lies near the western wall of the ionization cone and coincides with the inner radio jet (PA ∼ 11 ◦ ). The large distance from the core suggests that the K � -band emission of the northern extended component is scattered light from the western cavity region and the radio jet region.

Matching Stellar Models to Oscillation Data

Abstract: We describe a method to match stellar models to a set of low-l p-mode oscillation frequencies. The method provides a quality of fit measure similar to that obtained from a χ2 fit. With a sufficiently dense grid of stellar models, the method can determine the best-fitting model to the oscillation data as constrained solely by the oscillation data. That is to say, the method can be used to constrain the mass, age, composition, surface temperature, and luminosity of a star from the oscillation data. We evaluate the method on solar data and apply the method to the recently observed oscillation data for α Cen and α UMa.

On dominating the Cartesian product of a graph and K

Abstract: In this paper we consider the Cartesian product of an arbitrary graph and a complete graph of order two. Although an upper and lower bound for the domination number of this product follow easily from known results, we are interested in the graphs that actually attain these bounds. In each case, we provide an infinite class of graphs to show that the bound is sharp. The graphs that achieve the lower bound are of particular interest given the special nature of their dominating sets and are investigated further.