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Showing papers by "Lehigh University published in 1996"


Journal ArticleDOI
TL;DR: In this article, an integrated theoretical model that explains how strategies for participating in the market for corporate control (acquisitions and divestitures) affect internal control is presented, and the model is extended to analyze the effect of different strategies on internal control.
Abstract: This research examines an integrated theoretical model that explains how strategies for participating in the market for corporate control (acquisitions and divestitures) affect internal control mec...

1,107 citations


Journal ArticleDOI
Chaim Kaufmann1
TL;DR: Ethnic civil wars are burning in Bosnia, Croatia, Rwanda, Burundi, Angola, Sudan, Turkey, Azerbaijan, Georgia, Chechnya, Tajikistan, Kashmir, Myanmar, and Sri Lanka, and are threatening to break out in dozens of other places throughout the world.
Abstract: Ethnic civil wars are burning in Bosnia, Croatia, Rwanda, Burundi, Angola, Sudan, Turkey, Azerbaijan, Georgia, Chechnya, Tajikistan, Kashmir, Myanmar, and Sri Lanka, and are threatening to break out in dozens of other places throughout the world.1 Many of these conflicts are are so violent, with so much violence directed against unarmed civilians, and are apparently intractable, that they have provoked calls for military intervention to stop them. As yet, however, the international community has done little and achieved less. Advocates of international action seek to redress the failures of local political institutions and elites by brokering political power-sharing arrangements, by international conservatorship to rebuild a functioning state, or by reconstruction of exclusive ethnic identities into wider, inclusive civic identities.2 Pessimists doubt these remedies, arguing that ethnic wars express primordial hatreds which cannot be reduced by outside intervention because they have been ingrained by long histories of inter-communal conflict.3

850 citations


Journal ArticleDOI
TL;DR: In this article, the molecular structures of the surface metal oxide species are reflected in the terminal M=O and bridging M-O-M vibrations, which are typically obtained in Raman and IR characterization studies of supported metal oxide catalysts.

781 citations


01 Jan 1996
TL;DR: In this paper, the impact of the cognitive revolution on social psychology has been discussed and the reasons for this are manifold' Some are rooted in the theoretical developments in the psychology of motivation (see Geen, 1995;-Gollwitzer, t99l; Heckh"or"t, 1991; Kuhl, 1983).
Abstract: guslu. 198ö; Karnio"l & Rois, 1996; Karoly, 1993; Kruglan.kil ibgO, Mclntosh & Martin, 1992; Tetlock, 1992) on thii theme. The reasons for this are manifold' Some are rooted in the theoretical developments in the psychology of motivation (see Geen, 1995;-Gollwitzer, t99l; Heckh"or"t, 1991; Kuhl, 1983), others within the impact of the cognitive revolution on social psychology (see Fiske, f9ö3b; Higgins & Bargh, 1987; Smith, 1994; Stevens &

408 citations


Journal ArticleDOI
TL;DR: In this paper, the authors use data on individual steel plants to study the relationship between regulators' enforcement of air pollution regulations and firms' compliance decisions and find that at the plant level, greater enforcement leads to greater compliance, while greater compliance leads to less enforcement.

344 citations


Journal ArticleDOI
TL;DR: In this article, an unconstrained elastic layer under statically self-equilibrating thermal or residual stresses is considered, where the layer is assumed to be a functionally graded material (FGM), meaning that its thermo-mechanical properties are continuous functions of the thickness coordinate.
Abstract: In this study an unconstrained elastic layer under statically self-equilibrating thermal or residual stresses is considered. The layer is assumed to be a functionally graded material (FGM), meaning that its thermo-mechanical properties are assumed to be continuous functions of the thickness coordinate. The layer contains an embedded or a surface crack perpendicular to its boundaries. Using superposition the problem is reduced to a perturbation problem in which the crack surface tractions are the only external forces. The dimensions, geometry, and loading conditions of the original problem are such that the perturbation problem may be approximated by a plane strain mode I crack problem for an infinite layer. After a general discussion of the thermal stress problem, the crack problem in the nonhomogeneous medium is formulated. With the application to graded coatings and interfacial zones in mind, the thickness variation of the thermo-mechanical properties is assumed to be monotonous. Thus, the functions suc...

331 citations


Journal ArticleDOI
TL;DR: Enough to be generally useful and to keep the algorithm analysis tractable to produce a better program in practice.
Abstract: enough to be generally useful and to keep the algorithm analysis tractable. Ideally, producing a better algorithm under the model should yield a better program in practice. The Parallel Random Access Machine (PRAM) [8] is the most popular model for representing and analyzing the complexity of parallel algorithms. A LogP A Practic

328 citations


Journal ArticleDOI
TL;DR: In this paper, the authors apply an empirical model to available DOC (dissolved organic C) data to estimate the depths to which 1% of surface UV-B and UV-A radiation penetrate for several major regions of North America.
Abstract: Climate warming in North America is likely to be accompanied by changes in other environmental stresses such as UV-B radiation. We apply an empirical model to available DOC (dissolved organic C) data to estimate the depths to which 1% of surface UV-B and UV-A radiation penetrate for several major regions of North America. UV attenuation depths are also estimated from DOC data collected from treatment and reference basins during the experimental acidification of Little Rock Lake, Wisconsin. In some regions of North America 25% of the lakes have 1% attenuation depths for UV-B radiation on the order of 4 m or more (western and northwestern U.S., Newfoundland). In other regions, 75% of the lakes have 1% attenuation depths for UV-B shallower than 0.5 m (Florida, upper midwestern U.S., northwestern Ontario, Quebec, and Nova Scotia). Attenuation depths for UV-A radiation are -2.5 times as deep as those for UV-B. Experimental acidification approximately doubled the estimated 1% attenuation depths for UV radiation in Little Rock Lake. The strong dependence of 1% attenuation depth on DOC below the l-2 mg liter-l DOC range suggests that UV attenuation in low DOC lakes is highly sensitive to even very small changes in DOC. We conclude that changes in climate, lake hydrology, acid deposition, and other environmental factors that alter DOC concentrations in lakes may be more important than stratospheric ozone depletion in controlling future UV environments in lakes.

326 citations


Journal ArticleDOI
TL;DR: In this article, free corrosion immersion experiments were conducted on a commercial airframe material, Al 2024-T3 (UNS A92024), in 0.5 M sodium chloride (NaCl) solution to investigate the role of microcon...
Abstract: Free corrosion immersion experiments were conducted on a commercial airframe material, Al 2024-T3 (UNS A92024), in 0.5 M sodium chloride (NaCl) solution to investigate the role of microcon...

318 citations


Journal ArticleDOI
12 Dec 1996-Nature
TL;DR: The authors presented a reconstruction of drought intensity and frequency over the past 2,300 years in the Northern Great Plains, based on lake salinity fluctuations inferred from fossil diatom assemblages.
Abstract: EXTREME large-scale droughts in North America, such as the 'Dust Bowl' of the 1930s, have been infrequent events within the documented history of the past few hundred years, yet this record may not be representative of long-term patterns of natural variation of drought intensity and frequency. In the Great Plains region of central North America, historical droughts have persisted longer than in any other part of the United States1, but no detailed records of drought patterns in this region have hitherto been obtained that extend beyond the past 500 years. Here we present a reconstruction of drought intensity and frequency over the past 2,300 years in the Northern Great Plains, based on lake salinity fluctuations inferred from fossil diatom assemblages. This record, of sub-decadal resolution, suggests that extreme droughts of greater intensity than that of the 1930s were more frequent before AD 1200. This high frequency of extreme droughts persisted for centuries, and was most pronounced during AD 200–370, AD 700–850 and AD 1000–1200. We suggest that before AD 1200, the atmospheric circulation anomalies that produce drought today were more frequent and persistent.

289 citations


Journal ArticleDOI
TL;DR: In this article, social interactions at fraternities that undergraduate women identified as places where there is a high risk of rape are compared to those that were identified as low risk as well as two local bars.
Abstract: Social interactions at fraternities that undergraduate women identified as places where there is a high risk of rape are compared to those at fraternities identified as low risk as well as two local bars. Factors that contribute to rape are common on this campus; however, both men and women behaved differently in different settings. Implications of these findings are considered.

Journal ArticleDOI
TL;DR: In this paper, the authors present a dimensionless criterion that can be used to characterize and unify the critical conditions required for onset of purely elastic instabilities in a wide range of different flow geometries.
Abstract: We present a new dimensionless criterion that can be used to characterize and unify the critical conditions required for onset of purely elastic instabilities in a wide range of different flow geometries. This scaling incorporates both the presence of non-zero elastic normal stresses in the fluid plus the magnitude of the streamline curvature in the flow, and it can be thought of as the viscoelastic complement of the Gortler number. We present detailed experimental and theoretical evidence that justifies and generalizes the form of the dimensionless criterion. We show how this criterion naturally arises from the linearized stability equations governing the viscoelastic flow and apply it to analytical and experimental results in a number of standard benchmark problems. In geometrically simple flows (e.g. torsional flows such as those in a circular Couette cell or a cone-and-plate rheometer) a characteristic radius of curvature of the streamlines may be readily identified and an analytical solution for the undisturbed base flow can be found. However, in the more complex flows characteristic of those found in commercial polymer processing operations, the base flow must typically be determined numerically and the streamline curvature varies in a complex manner throughout the flow. In the former case, we show how our scaling reduces to well-established results in the literature and for the latter case we present a particularly simple approach for understanding and quantifying the sensitivity of the critical conditions for onset of elastic instability to dimensionless geometric design parameters such as the aspect ratio of the test cell. The generality of the scaling is confirmed by applying it to new experimental measurements in a lid-driven cavity and numerical linear stability calculations for flow past a cylinder in a channel. We also show how the scaling may be generalized to incorporate, at least qualitatively, the variation in the critical conditions with other rheological parameters such as changes in the solvent viscosity, shear-thinning in the viscometric functions, a spectrum of relaxation times and a non-zero second normal stress coefficient. In a number of cases, these modifications and the predicted scaling of the critical onset conditions for purely elastic instabilities in other complex geometries, such as planar contractions or eccentric rotating cylinders, remain to be confirmed by future experiments or calculations.

Journal ArticleDOI
D. Frey1
TL;DR: In this paper, a new method of analog filter design is proposed where nonlinear active components are a natural part of a filter realizing an overall linear transfer function, which is articulated in the generation of the class of so-called "Exponential State Space" (ESS) filters.
Abstract: A new method of analog filter design is proposed where nonlinear active components are a natural part of a filter realizing an overall linear transfer function. This approach to design is articulated in the generation of the class of so-called "Exponential State Space" (ESS) filters. An outgrowth of "log filters", ESS filters are created via a mapping on the state space of a linear filter. Specifically, the state variables are equal to simple functions of exponentials or node voltages. The use of exponential, hyperbolic tangent, and hyperbolic sine mappings is shown to produce realizable nodal equations that result in "log", "tanh" and "sinh" filters, respectively. Aspects of interpretation and realization of the transformed state equations are discussed. It is shown that sinh filters are class AB filters, which is an intriguing extension of a concept introduced by Seevinck (1990). The different filter types are compared to an analogous standard transconductance-C filter via simulation of a band-pass filter with a Q of 5. All filters demonstrate tunability over a 100 to 1 range with excellent frequency response stability and accuracy over the tuning range, which extends to 5 MHz. These results and IMD and noise performance are given using both ideal transistors and transistors whose cutoff frequency equals approximately 300 MHz.

Journal ArticleDOI
TL;DR: In this article, the synthesis, morphology and mechanical properties of interpenetrating polymer networks are reviewed, with special emphasis on dual phase continuity, and the number of physical entanglements that arise in homo-IPNs.
Abstract: An interpenetrating polymer network, IPN, is defined as a combination of two or more polymers in network form, at least one of which is polymerized and/or crosslinked in the immediate presence of the other(s). The synthesis, morphology and mechanical properties of recent works are reviewed, with special emphasis on dual phase continuity, and the number of physical entanglements that arise in homo-IPNs. The concepts of phase diagrams are applied, especially to simultaneous interpenetrating network phase separations and gelations. Recent engineering applications are discussed.

Journal ArticleDOI
TL;DR: In this paper, a systematic investigation of the selective catalytic reduction (SCR) of NO by NH3over V2O5/TiO2catalysts of variable vanadia loading has been carried out at 623 K. The structure of various catalysts, as well as adsorbed species present on their surface, was characterized byin situRaman and infrared spectroscopies.

Journal ArticleDOI
TL;DR: In this article, a series of supported vanadia catalysts were investigated for selective catalytic reduction of NO with NH3 to obtain additional insight into this important industrial reaction, and the influence of surface vanadia coverage, promoters (surface tungsten oxide, niobium oxide, and sulfate species), and specific oxide support (TiO2, A l 2 O 3, and SiO2) was examined.

Journal ArticleDOI
TL;DR: In this paper, a review of the factors that determine the concentrations of mobile charged species and their contributions to the electrical conductivities of perovskite ferroelectrics are reviewed.

Journal ArticleDOI
TL;DR: In this article, a direct method of estimating adhesion and surface free energy is proposed based on contact mechanics, which measures the deformation produced on contacting elastic semispheres under the influence of surface forces and external loads.
Abstract: This review is concerned primarily with the correlation between the interfacial interactions and the constitutive properties of low-energy organic surfaces. It starts with a discussion on the estimation of the surface free energy of organic solids from contact angles, followed by a review of the surface energetics and adhesion. The experimental measurements of surface free energy, in most cases, are themselves dependent upon the specific models of interfacial energetics and therefore are indirect. A direct method of estimating adhesion and surface free energy is based on contact mechanics, which measures the deformation produced on contacting elastic semispheres under the influence of surface forces and external loads, Since the equilibrium is described by the balance of the elastic and surface forces of the system, the load-deformation data can be translated directly to estimate the adhesion and surface free energies. In most cases however, the contact deformations obtained from the loading and unloading cycles exhibit hysteresis, which are sensitive to the structure and chemical compositions of the interfaces. For non-hysteretic systems, the surface free energies obtained from these contact deformations compare well with the values obtained from contact angles. The application of this method to the studies of dispersion and hydrogen-bonding interaction is reviewed.

Journal ArticleDOI
01 Sep 1996-Polymer
TL;DR: In this article, the role of particle cavitation in toughening of rubber-toughened polymers was further elucidated through comparative examination of epoxies modified by conventional rubber modifiers and hollow plastic particles.

Journal ArticleDOI
TL;DR: The nucleation of fatigue cracks from corrosion pits was investigated by conducting fatigue experiments on open-hole specimens of a 2024-T3 aluminum alloy in 0.5 M NaCl solution at room temperature and different load frequencies from 0.1 to 20 Hz.
Abstract: The nucleation of fatigue cracks from corrosion pits was investigated by conducting fatigue experiments on open-hole specimens of a 2024-T3 aluminum (bare) alloy in 0.5 M NaCl solution at room temperature and different load frequencies from 0.1 to 20 Hz. The maximum cyclic stresses applied at the hole ranged from 144 to 288 MPa and the load ratio, R , was 0.1. A specimen subjected to pre-corrosion in the NaCl solution prior to corrosion fatigue was also investigated. Pitting was found to be associated with constituent particles in the hole and pit growth often involved coalescence of individual particle-nucleated pits. Fatigue cracks typically nucleated from one or two of the larger pits, and the size of the pit at which the fatigue crack nucleates is a function of stress level and load frequency. The observations indicate that the nucleation of corrosion fatigue cracks essentially results from a competition between the processes of pitting and crack growth. Pitting predominates in the early stage of the corrosion fatigue process, and is replaced by corrosion fatigue crack growth. Based on these results, two criteria are proposed to describe the transition from pit growth to fatigue crack growth: (1) the stress intensity factor of the equivalent surface crack has to reach the threshold stress intensity factor, Δ K th , for fatigue crack growth, assuming that a corrosion pit may be modeled by an equivalent semi-elliptical surface crack, and (2) the time-based corrosion fatigue crack growth rate also exceeds the pit growth rate.

Journal ArticleDOI
TL;DR: In this paper, past lake-water salinity from fossil diatom assemblages were used to infer past climatic conditions at Moon Lake, a climatically sensitive site in the northern Great Plains.
Abstract: Estimates of past lake-water salinity from fossil diatom assemblages were used to infer past climatic conditions at Moon Lake, a climatically sensitive site in the northern Great Plains. A good correspondence between diatom-inferred salinity and historical records of mean annual precipitation minus evapotranspiration (P - ET) strongly suggests that the sedimentary record from Moon Lake can be used to reconstruct past climatic conditions. Century-scale analysis of the Holocene diatom record indicates four major hydrological periods: an early Holocene transition from an open freshwater system to a closed saline system by 7300 B.P., which corresponds with a transition from spruce forest to deciduous parkland to prairie and indicates a major shift from wet to dry climate; a mid-Holocene period of high salinity from 7300 to 4700 B.P., indicating low effective moisture (P - ET); a transitional period of high salinity from 4700 to 2200 B.P., characterized by poor diatom preservation; and a late Holocene period of variable lower salinity during the past 2,200 yr, indicating fluctuations in effective moisture.

Journal ArticleDOI
TL;DR: In this article, resource-based physiology of the eight important planktonic diatom species in the large lakes of the Yellowstone region can be used to explain their relative abundances and seasonal changes.
Abstract: Resource-based physiology of the eight important planktonic diatom species in the large lakes of the Yellowstone region can be used to explain their relative abundances and seasonal changes. The diatoms are ranked along resource ratio gradients according to their relative abilities to grow under limitation by Si, N, P, and light. Hypotheses based on resource physiology can be integrated with observations on seasonal changes in diatom assemblages to explain the present distributions of diatoms and to test the causal factors proposed to explain diatom distributions over the Holocene. Knowledge of the limnology of these lakes and process-oriented physiology provide the basis for a more detailed interpretation of the paleorecord and a firmer basis for landscape-level transfer functions for fine-scale climate reconstruction.

Journal ArticleDOI
TL;DR: In this article, the concept of creating functionally graded metal-ceramic composite microstructures for thermal barrier coatings used in gas-turbine applications was explored, which offers the possibility of significantly improving the life and reliability of thermal barrier coating.
Abstract: This feature article explores the concept of creating functionally graded metal-ceramic composite microstructures for thermal barrier coatings used in gas-turbine applications. From a thermomechanical perspective, this concept offers the possibility of significantly improving the life and reliability of thermal barrier coatings. However, prior research reveals that progress has been somewhat limited because of the oxidative instability exhibited by some metal-ceramic composite microstructures. The present study addresses some of the materials criteria and research issues associated with preparing chemically stable, yet mechanically durable, graded metal-ceramic microstructures for realistic application environments.

Journal ArticleDOI
Y.F. Chen1, F. Erdogan1
TL;DR: In this paper, the debonding problem for a composite layer that consists of a homogeneous substrate and a non-homogeneous coating is considered, and the main variables in the problem are two dimensionless length parameters and nonhmogeneity constant.
Abstract: The debonding problem for a composite layer that consists of a homogeneous substrate and a non-homogeneous coating is considered. It is assumed that the problem is one of plane strain or generalized plane stress and the elastic medium contains a crack along the interface. It is further assumed that the thermomechanical properties of the medium are continuous functions of the thickness coordinate with discontinuous derivatives and the kink line of the property distributions corresponds to the “interface”. The mixed-mode crack problem is formulated for arbitrary crack surface tractions and sample results are given for uniform normal and shear tractions. The main variables in the problem are two dimensionless length parameters and a nonhmogeneity constant. Calculated results consist of primarily the stress intensity factors and the strain energy release rate and are partly intended to provide benchmark solutions for further numerical studies.

Journal ArticleDOI
TL;DR: In this paper, the authors conducted a survey of 837 firms identified in the Venture Capital Journal that had received financing from venture capital firms and found that significant differences exist among VCs in their evaluation of business management and operational assistance, and that the optimal level of involvement is also partially contingent upon the NVT openness to learning.

Proceedings Article
07 Jun 1996
TL;DR: In this paper, a new type of incoherently coupled soliton pairs is shown to be possible under steady-state conditions provided that their carrier beams share the same polarization and wavelength and are mutually incoherent.
Abstract: Summary form only given. Recently it was demonstrated that spatial optical solitons at /spl mu/W power levels can be supported in photorefractive (PR) media. We show that a new type of incoherently coupled soliton pairs is possible under steady-state conditions provided that their carrier beams share the same polarization and wavelength and are mutually incoherent. They can be readily realized in a simple experimental setup where the optical beams co-propagate collinearly in a biased PR crystal in which case they experience equal electrooptic coefficients.

Journal ArticleDOI
TL;DR: In this paper, a low-temperature Fe-Ni phase diagram is presented, which is consistent with the available theoretical diagram in that α/Ni3Fe equilibrium was found at low temperatures.
Abstract: The low-temperature Fe-Ni phase diagram was assessed experimentally by investigating Fe-Ni regions of meteorites using high resolution analytical electron microscopy techniques. The present phase diagram differs from the available experimental phase diagram based on observations of meteorite structure, but it is consistent with the available theoretical diagram in that α/Ni3Fe equilibrium was found at low temperatures. The a phase containing 3.6 wt.% Ni is in local equilibrium with the γ′ (Ni3Fe) phase containing 65.5 wt.% Ni, while the γ′' (FeNi) phase is present as a metastable phase. The new phase diagram incorporates a monotectoid reaction (γ1 → α + γ2, where (γ1 is a paramagnetic fcc austenite, a is a bcc ferrite, and γ2 is a ferromagnetic fcc austenite) at about 400 °C, a eutectoid reaction (γ2 → α + γ′) at about 345 °C, and a miscibility gap associated with a spinodal region at low temperatures. The miscibility gap is located between 9.0 and 51.5 wt. % Ni at ∼200 °C. The new low-temperature Fe-Ni phase diagram is consistent with all the phases observed in the metallic regions of meteorites.


Journal ArticleDOI
TL;DR: In this article, the authors present a detailed analysis of the last 15,000 to 12,000 years of the Laghi Di Monticchio fossil pollen record, which provides evidence of former lake environments as well as data on the upland forest.

Patent
06 Jun 1996
TL;DR: In this article, a process for the preparation of crosslinked water-swellable polymer particles is described, which is useful for implantation, soft tissue augmentation, and scaffolding to promote cell growth.
Abstract: The invention is a process for the preparation of crosslinked water-swellable polymer particles. First, an aqueous polymer solution containing a water-soluble polymer having at least one functional group or charge, is combined with aqueous medium. The aqueous polymer solution is then mixed under moderate agitation with an oil medium and an emulsifier to form an emulsion of droplets of the water-soluble polymer. A crosslinking agent capable of crosslinking the functional groups and/or charges in the water-soluble polymer is then added to the emulsion to form crosslinked water-swellable polymer particles. The invention also includes the particles formed by the process and aqueous dispersions containing the particles which are useful for administering to an individual. The particles of the invention are useful for implantation, soft tissue augmentation, and scaffolding to promote cell growth.