Showing papers by "Clarkson University published in 2001"

Breakdown of the internet under intentional attack.

Abstract: We study the tolerance of random networks to intentional attack, whereby a fraction $p$ of the most connected sites is removed. We focus on scale-free networks, having connectivity distribution $P(k)\ensuremath{\sim}{k}^{\ensuremath{-}\ensuremath{\alpha}}$, and use percolation theory to study analytically and numerically the critical fraction ${p}_{c}$ needed for the disintegration of the network, as well as the size of the largest connected cluster. We find that even networks with $\ensuremath{\alpha}\ensuremath{\le}3$, known to be resilient to random removal of sites, are sensitive to intentional attack. We also argue that, near criticality, the average distance between sites in the spanning (largest) cluster scales with its mass, $M$, as $\sqrt{M}$, rather than as ${log}_{k}M$, as expected for random networks away from criticality.

Employee Empowerment: An Integrative Psychological Approach

Abstract: An integrative psychological approach to employee empowerment was developed based on the premise that the psychological experience of power underlies feelings of empowerment. This research extends existing perspectives on empowerment by incorporating the empowering effect of valued goals, such as those provided by transformational leadership. Goal internalisation was identified as a major component of the psychological experience of empowerment, in addition to the two traditional facets of perceptions of control over the work environment and perceptions of self-efficacy or competence. Standard measure development procedures using a sample of employed individuals from Quebec, Canada and subsequent validation with an organisational sample from Ontario, Canada yielded a three-factor scale of psychological empowerment corresponding to these three dimensions. The implications of defining empowerment as a psychological state and the need for multiple measures of empowerment are also discussed.

The role of interpersonal liking in building trust in long-term channel relationships

Abstract: This article explores the important role of liking in the development of the buyer’s trust in the sales rep. The authors argue that liking’s role is richer and qualitatively different from that of the more cognitive antecedents of trust. They posit that many cognitive antecedents of trust operate mainly through liking. They argue that as the buyer-sales rep relationship matures, liking plays an even more important role in influencing trust. The authors empirically test a model delineating the mediating role of liking in developing trust. They find that when the relationship between the buyer and the sales rep is young, liking partially mediates the effect of similarity of business values and fully mediates the influence of frequency of personal interaction on trust. Moreover, as the buyer’s relationship with the rep ages, liking takes the foreground in trust development, while more cognitive antecedents recede into the background.

Atmospheric aerosol over Vermont: chemical composition and sources.

Abstract: Aerosol chemical composition data for PM2.5 samples collected during the period from 1988 to 1995 at Underhill, VT, were analyzed. Sulfur and black carbon mass concentrations ranged from 0.01 to 6.5 μg m-3 and from 0.05 to 2.2 μg m-3, respectively, while the total fine aerosol mass concentration ranged from 0.2 to 51.1 μg m-3. Seasonal variations with maxima during the summer and minima in winter/spring were observed for sulfur and the fine mass concentrations. No annual pattern was observed for black carbon. Seasonal variations for most of the other anthropogenic species had maxima in winter and spring and minima in the summer. A factor analysis method, positive matrix factorization (PMF), utilizing error estimates of the data to provide optimum data point scaling was used to obtain information about possible sources of the aerosol. An 11-factor solution was obtained. The six sources representing wood burning, coal and oil combustion, coal combustion emissions plus photochemical sulfate production, metal...

Chemical Self-assembly for Electronic Applications

Abstract: The current state of spontaneous formation of self-assembled monolayers (SAMs) on different substrates as well as on nanoparticles (referred to as monolayer-protected clusters, MPCs) is surveyed. Attention is then focused onto the assembly and self-assembly of nanoparticles (including MPCs), polymers, and polyelectrolytes into two-dimensional (2D) arrays and three-dimensional (3D) networks. Examples are given for the potential electronic applications of SAMs, MPCs, and the 2D and 3D structures fabricated from them and from polymers and polyelectrolytes. These examples include the formation of junctions, heterojunctions, and single-electron-transfer devices.

Effects of nonplastic fines on the liquefaction resistance of sands

Abstract: A laboratory parametric study utilizing cyclic triaxial tests was performed to clarify the effects of nonplastic fines on the liquefaction susceptibility of sands. Studies previously published in the literature have reported what appear to be conflicting results as to the effects of silt content on the liquefaction susceptibility of sandy soils. The current study has shown that if the soil structure is composed of silt particles contained within a sand matrix, the resistance to liquefaction of the soil is controlled by the relative density of the soil and is independent of the silt content of the soil. For soils whose structure is composed of sand particles suspended within a silt matrix, the resistance to liquefaction is again controlled by the relative density of the soil, but is lower than for soils with sand-dominated matrices at similar relative densities. In this case, the resistance to liquefaction is essentially independent of the amount and type of sand. These findings suggest the need for further evaluation of the effects of nonplastic fines content upon penetration resistance, and the manner in which this relationship affects the simplified methods currently used in engineering practice to evaluate the liquefaction resistance of silty soils.

Source regions for atmospheric aerosol measured at Barrow, Alaska.

Abstract: Aerosol data consisting of condensation nuclei (CN) counts, black carbon (BC) mass concentration, and aerosol light scattering coefficient at the wavelength of 450 nm (SC) measured at Barrow, AK, from 1986 to 1997 have been analyzed. BC and SC show an annual cycle with the Arctic haze maxima in the winter and spring and the minima in the summer. The CN time series shows two maxima in March and August. Potential source contribution function (PSCF) that combines the aerosol data with air parcel backward trajectories was applied to identify potential source areas and the preferred pathways that give rise to the observed high aerosol concentrations at Barrow. Ten-day isentropic back trajectories arriving twice daily at 500 and 1500 m above sea level were calculated for the period from 1986 to 1997. The PSCF analyses were performed based on the 80th percentile criterion values for the 2- and 24-h averages of the measured aerosol parameters. There was a good correspondence between PSCF maps for the 2- and 24-h ...

Approximation of nonlinear systems with radial basis function neural networks

Abstract: A technique for approximating a continuous function of n variables with a radial basis function (RBF) neural network is presented. The method uses an n-dimensional raised-cosine type of RBF that is smooth, yet has compact support. The RBF network coefficients are low-order polynomial functions of the input. A simple computational procedure is presented which significantly reduces the network training and evaluation time. Storage space is also reduced by allowing for a nonuniform grid of points about which the RBFs are centered. The network output is shown to be continuous and have a continuous first derivative. When the network is used to approximate a nonlinear dynamic system, the resulting system is bounded-input bounded-output stable. For the special case of a linear system, the RBF network representation is exact on the domain over which it is defined, and it is optimal in terms of the number of distinct storage parameters required. Several examples are presented which illustrate the effectiveness of this technique.

California Electricity Situation

Abstract: In a three-phase system, voltage unbalance takes place when the magnitudes of phase or line voltages are different and the phase angles differ from the balanced conditions, or both. This letter reviews three definitions of voltage unbalance developed by NEMA, IEEE, and the power community, respectively. The differing definitions of voltage unbalance are analyzed in order to understand the implications of their use.

The Motion of Bubbles and Drops in Reduced Gravity

Abstract: Part I. Introduction: 1. The role of gravity and interfacial tension in the motion of bubbles and drops 2. The governing equations Part II. The Motion of Isolated Bubbles and Drops: 3. Motion driven by a body force 4. Thermocapillary motion Part III. Interactions of Bubbles and Drops: 5. General solutions 6. Interactions when motion is driven by a body force 7. Interactions when motion is driven by thermocapillarity Part IV. Related Topics: 8. Mass transfer between a bubble or drop and a continuous phase 9. Motion driven by the interface in a body of fluid References.

Rapid evolution of wing size clines in Drosophila subobscura

Abstract: Parallel latitudinal clines across species and continents provide dramatic evidence of the efficacy of natural selection, however little is known about the dynamics involved in cline formation. For example, several drosophilids and other ectotherms increase in body and wing size at higher latitudes. Here we compare evolution in an ancestral European and a recently introduced (North America) cline in wing size and shape in Drosophila subobscura. We show that clinal variation in wing size, spanning more than 15 degrees of latitude, has evolved in less than two decades. In females from Europe and North America, the clines are statistically indistinguishable however the cline for North American males is significantly shallower than that for European males. We document that while overall patterns of wing size are similar on two continents, the European cline is obtained largely through changing the proximal portion of the wing, whereas the North American cline is largely in the distal portion. We use data from sites collected in 1986/1988 (Pegueroles et al. 1995) and our 1997 collections to compare synchronic (divergence between contemporary populations that share a common ancestor) and allochronic (changes over time within a population) estimates of the rates of evolution. We find that, for these populations, allochronically estimated evolutionary rates within a single population are over 0.02 haldanes (2800 darwins), a value similar in magnitude to the synchronic estimates from the extremes of the cline. This paper represents an expanded analysis of data partially presented in Huey et al. (2000).

Does Relationship Marketing Age Well

Abstract: Most managers agree that close co-operative relationships between business partners yield benefits to all parties. However, some question whether these benefits continue as the relationship ages. This article reports on a study designed to answer this question. The study suggests that, however long the relationship, building trust, commitment and the other components of Relationship Marketing (RM) continue to have a positive effect on the performance of business partners. However, it also shows that, over time, the positive effect diminishes. The authors suggest that managers need to recognize this, and to identify the true costs of building relationships so as to judge whether the diminishing returns justify the effort. Ultimately, managers need to vary their handling of each relationship because standardized RM practices are unlikely to be effective.

A Model for Mechanical Wear and Abrasive Particle Adhesion during the Chemical Mechanical Polishing Process

Abstract: Abrasive particle-surface interactions are analyzed and processes of surface removal by adhesive and abrasive wear mechanisms during chemical mechanical polishing (CMP) are studied. The mechanical contact theory is used, and a model for interactions of pad asperities with abrasive particles and wafer is developed. The cases of hard and soft pads and dilute and dense slurries are analyzed. A model for the particle-scale surface removal process in the chemical-mechanical polishing is developed. The influence of abrasive particle adhesion to the surface is included in the analysis. Variations of polishing rate with pressure, abrasive particle size and concentration, as well as pad characteristics (including asperity distribution and asperity elastic and plastic deformation) are studied. The functional dependence of the polishing rate on pressure and velocity was found to be related to the distribution of pad asperities. The linear variation predicted by Preston's equation follows when the pad asperities have a random distribution. The sublinear dependence, however, is obtained when the pad asperities have a wavy distribution. The results also show that the abrasive particle adhesion affects the CMP process. The model predictions are presented in graphical form and are compared with the available semiempirical correlations and discussed.

Multiple imputation for multivariate data with missing and below-threshold measurements: time-series concentrations of pollutants in the Arctic.

Abstract: Summary. Many chemical and environmental data sets are complicated by the existence of fully missing values or censored values known to lie below detection thresholds. For example, week-long samples of airborne particulate matter were obtained at Alert, NWT, Canada, between 1980 and 1991, where some of the concentrations of 24 particulate constituents were coarsened in the sense of being either fully missing or below detection limits. To facilitate scientific analysis, it is appealing to create complete data by filling in missing values so that standard complete-data methods can be applied. We briefly review commonly used strategies for handling missing values and focus on the multiple-imputation approach, which generally leads to valid inferences when faced with missing data. Three statistical models are developed for multiply imputing the missing values of airborne particulate matter. We expect that these models are useful for creating multiple imputations in a variety of incomplete multivariate time series data sets.

Scale of Agricultural Production, Civic Engagement, and Community Welfare

Abstract: Using data from the Census of Agriculture and other secondary sources, we examine the relationship between scale offarm operations in a county and the well-being of local residents. Following earlier work by C. Wright Mills and Walter Goldschmidt, we hypothesize that in agriculture dependent counties that are dominated by a small handful of very largefarms, the level of community welfare will be significantly lower than in counties in which agriculture is organized around smaller-scalefarm operations. Findings show that scale offarm operations is related to well-being. However, this relationship is mediated by the level of civic engagement and the strength of the economically independent middle class. A theory of civic community is proposed to accountfor thesefindings. At the end of World War II, two research reports commissioned by a U.S. Senate Special Committee to study problems of American small business, examined the relationship between the concentration of economic power at the community level and the social and economic well-being of local residents (Goldschmidt [ 1946] 1978; Mills & Ulmer [1946] 1970)'. The thesis advanced in both of these studies was that communities in which the economic base was composed of a plethora of relatively small, locally owned firms would manifest higher levels of social, economic, and political welfare and well-being than communities where the economic base was dominated by a few large absentee-owned firms.

Optimal protection from impact, shock and vibration

Abstract: Systems with Isolators and Problems from Optimizing Their Characteristics. Optimal Protection of Rectilinearly Moving Systems from an Instantaneous Impact. Optimal Protection of Rotating Objects from an Instantaneous Impact. Optimal Isolation for a Class of Disturbances. Optimization of Shock Isolators for an Object with Incompletely Prescribed Mass. Optimization of Vibration Isolation Systems. Optimal Damping of Transient Motion in Multi-Degree-of-Freedom Systems. Computational Methods for a Limiting Performance Analysis. Design of Optimal Shock Isolators. Is Optimal Shock Isolation Always Provided by a Constant Control Force?

IText: Future Directions for Research on the Relationship between Information Technology and Writing.

Abstract: Most people who use information technology (IT) every day use IT in text-centered interactions. In e-mail, we compose and read texts. On the Web, we read (and often compose) texts. And when we crea...

Indirect Interaction of Solid-State Qubits via Two-Dimensional Electron Gas

Abstract: We propose a mechanism of long-range coherent coupling between nuclear spin qubits in semiconductor-heterojunction quantum information processing devices. The coupling is via localized donor electrons which interact with the two-dimensional electron gas. An effective interaction Hamiltonian is derived and the coupling strength is evaluated. We also discuss mechanisms of decoherence and consider gate control of the interaction between qubits. The resulting quantum computing scheme retains all the control and measurement aspects of earlier approaches, but allows qubit spacing at distances of the order of 100 nm, attainable with the present-day semiconductor device technologies.

Ionization Processes and Proton Binding in Polyprotic Systems: Small Molecules, Proteins, Interfaces, and Polyelectrolytes

Abstract: Binding of ions to various materials, such as small molecules, proteins, polymers, colloid particles, and membranes, represents a central theme in basic and applied chemistry. Particularly, the case of proton binding to these substances (i.e., their acid-base behavior) has been a focus of research in many branches of chemistry since the turn of the century. One important topic in physical, analytical, and inorganic chemistry is the measurement, compilation, and prediction of acid-base properties of simple molecules or solvated metal ions.(1–8) These topics remain of much relevance for the development of new analytical techniques and tailoring of buffering or complexing agents.(7,9) Accurately known ionization constants also represent a rather stringent testing ground of our ab initio simulation capabilities of simple molecules in water.(10) Acid-base properties of proteins have been also investigated from early on.(11–14) This field has now matured into an active area of modern biochemistry with implications to the current view of protein folding, enzyme action, and photosynthesis.(15–17) Similar studies of weak polyelectrolytes were initiated in polymer science almost simultaneously(18–21) These systems represent an ongoing challenge to our understanding of acid-base equilibria.(22–25) The substantial interest in polyelectrolytes is due to their use as complexing, flocculating, or stabilizing agents, and their importance in various applications in catalysis, material engineering, biochemistry, and water purification.(26–28)

A framework for information systems planning for e‐business

Abstract: E‐business information systems are computer applications that leverage intra‐ and inter‐firm process and systems integration. Considering the growth and strategic importance of e‐business, while it is important for organizations to carefully plan for and architect e‐business systems, none of the existing information systems planning models is adequate for the task. An e‐business architecture planning model is developed by identifying 12 generic e‐business models and three axes on which drivers of the information architecture needs of e‐business firms fall. Sowa and Zachman’s information architecture is augmented to further facilitate e‐business information systems architecture planning.

Parental and developmental temperature effects on the thermal dependence of fitness in Drosophila melanogaster.

Abstract: Cross-generational effects refer to nongenetic influences of the parental phenotype or environment on offspring phenotypes. Such effects are commonly observed, but their adaptive significance is largely unresolved. We examined cross-generational effects of parental temperature on offspring fitness (estimated via a serial-transfer assay) at different temperatures in a laboratory population of Drosophila melanogaster. Parents were reared at 18°C, 25°C, or 29°C (Tpar) and then their offspring were reared at 18°C, 25°C, or 29°C (Toff) to evaluate several competing hypotheses (including an adaptive one) involving interaction effects of parental and offspring temperature on offspring fitness. The results clearly show that hotter parents are better; in other words, the higher the temperature of the parents, the higher the fitness of their offspring, independent of offspring thermal environment. These data contradict the adaptive cross-generational hypothesis, which proposes that offspring fitness is max...