Showing papers by "Lehigh University published in 1990"

Venture Capitalist Certification in Initial Public Offerings

Abstract: With more businesses going public, the certification of their value and offering price is a necessity, acting as a means of attracting investors and of enhancing further financial success. While auditors and underwriters typically certify the value of an initial public offering (IPO), venture capitalists, as investors in a firm, also have knowledge of the firm's value, leading researchers to explore the potential role of venture capitalists in certifying an IPO's offering price. The process of venture capital (VC) firm certification is described. Utilizing Investment Dealer's Digest Corporate Database (IDD), a representative sample of both VC backed and non-VC backed firms (320 each) is compiled, and matched for industry and offering size. The role of underwriters and auditors in certifying a firm's value is scrutinized, including their respective relationships with VC backed firms. The data regarding initial returns and offering expenses for IPOs are analyzed for both VC backed and non-VC backed firms. Venture capitalists are found to play a significant role in firm certification, including an implication of firm quality due to their investment in the firm. The data suggest that VC backed firms, when compared to non-VC backed firms, tend to be younger, typically comprised of assets of greater median book value, and have attained a larger percentage of equity in the IPO's capital structure. Additionally, VC backing often results in the utilization of higher quality underwriters and auditors, while simultaneously experiencing a decrease in costs associated with underpricing and underwriting. Although a few venture capitalists may cash-out of their investment following IPO, the majority of venture capitalists typically maintain their holdings in firms following the initial public offering. (AKP)

Determination of molybdenum–oxygen bond distances and bond orders by Raman spectroscopy

Abstract: A correlation is developed for relating Raman stretching frequencies of molybdenum–oxygen (MoO) bonds to their respective bond distances in molybdenum oxide compounds. MoO bond orders are also related to stretching frequencies. The MoO correlation is expected to offer invaluable insight into the structures of molybdate species in chemical systems which are not amenable to analysis by diffraction or other spectroscopic techniques. In the present study, the correlation is used to predict stretching frequencies for perfect MoO4 and MoO6 structures, and to determine MoO bond distances of the MoO6 octahedron in Ba2CaMoO6 as well as the dehydrated surface molybdate species in MoO3/Al2O3.

Phase separation in polystyrene latex interpenetrating polymer networks

Abstract: Polystyrene/polystyrene latex interpenetrating polymer networks (IPNs) were prepared by seeded emulsion polymerzation of styrene–divinylbenzene mixtures in crosslinked monodisperse polystyrene seed latexes. The resulting latexes comprised uniform nonspherical particles, which were formed by separation of the second-stage monomer from the crosslinked seed network during swelling and polymerization. The kinetics of phase separation were investigated by examining the changes in particle morphology using optical microscopy, which revealed that the phase separation was induced by the relaxation of the polymer chains before polymerization began and was enhanced by increased conversion. The thermodynamics of phase separation were investigated by analysis of the free-energy changes during swelling and polymerization, and the phase separation was described by a nucleation-and-growth mechanism. The results of this study have been applied to the design and synthesis of a series of uniform nonspherical particles of different morphology.

Behavioral momentum in the treatment of escape-motivated stereotypy.

Abstract: Descriptive and experimental analyses of stereotypy by a woman with severe mental retardation showed that the behavior was maintained by escape from demands. A sequence of high-probability requests issued immediately prior to a task-related request established a momentum of compliance that increased compliance with task-related demands. Increases in compliance were accompanied by collateral reductions in stereotypic behavior. A mechanism of response covariation, called functional incompatibility, and an animal analogue study for testing the validity of this mechanism are proposed.

Quantitative characterization of the acid-base properties of solvents, polymers, and inorganic surfaces

Abstract: The growing realization of the importance of intermolecular acid-base interactions in promoting the solubility, adsorption, and adhesion of polymers to other materials has caused a demand for the quantitative characterization of the acid-base properties of the commonly used solvents, polymers, and inorganic fillers and substrates. There have been several recent advances in the measurement techniques for such determinations, especially in the fields of inverse gas chromatography, microcalorimetry, ellipsometry, FTIR, NMR, and XPS spectroscopy, all leading to the capability of determining the Drago E and C constants or the Gutmann acceptor numbers (AN) or donor numbers (DN) for the acidic or basic sites of solvents, polymers, or inorganic surfaces. In the last year, new studies have also allowed the characterization of the specific acid-base cohesive interactions in solvents and polymers, and the determination, from contact angle measurements on polymers, of the surface concentration and strength of acidic ...

Bistable interstitial-carbon–substitutional-carbon pair in silicon

Abstract: A bistable interstitial-carbon--substitutional-carbon pair has been identified in electron-irradiated silicon by a combination of several spectroscopic experimental techniques. In the positive and negative charge states, the stable configuration of the defect involves a carbon-silicon ``molecule'' which occupies a single lattice site (each atom threefold coordinated) next to a substitutional-carbon atom (fourfold coordinated). In the neutral charge state, the defect rearranges its bonds so that both carbon atoms become substitutional (fourfold coordinated) with a twofold-coordinated silicon atom nestled between them. Detailed microscopic models and configurational-coordinate energy surfaces for each of the three charge states have been obtained.

Uniform nonspherical latex particles as model interpenetrating polymer networks

Abstract: Polystyrene/polystyrene latex interpenetrating polymer networks (IPNs) were prepared by seeded emulsion polymerization of styrene–divinylbenzene mixtures in crosslinked monodisperse polystyrene particles. The resulting latexes comprised uniform nonspherical particles, e.g., ellipsodal and egg-like singlets, symmetry and asymmetric doublets, and ice cream cone-like and popcorn-like multiplets. The nonspherical particles, which were formed by separation of the second-stage monomer from the crosslinked seed network during swelling and polymerization, are excellent models for studying phase separation in IPN's. The degree of phase separation increased with increasing degree of crosslinking of the seed particles, monomer/polymer swelling ratio, polymerization temperature, and seed particle size, and with decreasing divinylbenzene concentration in the swelling monomer. The results were consistent with a thermodynamic analysis based on the elastic-retractile force of the polymer network, the monomer/polymer mixing force, and interfacial tension force.

Coarsening‐Resistant Dual‐Phase Interprenetrating Microstructures

Abstract: Grain growth in a 50:50 (vol%) dual-phase mixture of Al2O3 and c-ZrO2 (cubic zirconia) is severely limited compared with that for either of the single phases. At 1650°C, the growth rates in the duplex composition are 160 and 3500 times lower than that for single-phase Al2O3 and c-ZrO2, respectively. The restriction of the grain growth is attributed to the limited mutual solubility and the physical constraint provided by the interpenetrating geometry of the two phases. Grain coordination number and dihedral angle are also considered as factor affecting grain stabilization in two-phase systems. A potentially important practical application of this work is the fabrication of grain-stabilized fibers for use as reinforcement in composite structures at elevated temperatures.

Charge transport and storage of low programming voltage SONOS/MONOS memory devices

Abstract: In this paper, a model based on two carrier conduction (electrons and holes) at both injecting boundaries (semiconductor bulk and gate electrode) is introduced to interpret the ERASE/WRITE characteristics of scaled SONOS devices. The amphoteric statistics describe the positive and negative charging of the deep-level traps in the nitride “memory” layer. Scaled SONOS/MONOS (polysilicon-oxide-nitride-oxide-semiconductor)/(metal-oxide- nitride-oxide-semiconductor) transistors and capacitors with the bottom (‘tunnel’) oxide layer thickness around 20 A, the final nitride layer thickness below 100 A, and the top (‘blocking’) oxide layer thickness between 35–50 A, have been fabricated and characterized. The results of the model are consistent with the experimental data, which permits physical insight into the mechanisms of charge injection, transport and storage during the ERASE/WRITE operation. Lattice imaging electron microscopy (TEM), ellipsometry, electrical capacitance, and chemical etchback techniques have been used to determine scaled SONOS/MONOS material parameters. The linear voltage ramp technique, which simultaneously measures the flatband voltage shift and separates the charges at the injecting boundary, and the dynamic pulse techniques of flatband tracking and threshold monitoring, which measure ERASE/WRITE, retention and endurance operations, have been employed to electrically characterize the scaled SONOS/MONOS devices. We have demonstrated a differential, saturated ERASE/WRITE flatband shift of 3.8 V with a ±5 V programming voltage for scaled-down SONOS/MONOS devices with dimensions of 20 A for the tunnel oxide, 50 A for the nitride, and 35 A for the blocking oxide. With ±5 V saturated ERASE/WRITE programming voltages and 10 6 ERASE/WRITE cycles, extrapolated retention gives a projected 10 year 0.5 V memory window at room temperature.

Acid-base properties of glass surfaces

Abstract: The adhesion of polymers to inorganic oxides such as glass is very dependent on acid-base interactions between the acidic or basic surface sites of the glass and the basic or acidic functional sites of the polymer. This paper reviews the principles of such interactions, methods of measuring the acidity or basicity of surface sites, and the enhanced mechanical properties of glass-reinforced polymer composites resulting from interfacial acid-base complexation. A new study is presented of the acid-base properties of fiberglass and of surface treatments with silane coupling agents and polyvinyl acetate. It illustrates calorimetric titration methods for assessing surface acidity and basicity, and correlates these findings with angular-dependent X-ray photoelectron spectroscopy (ADXPS).

Protein partitioning in PEG/dextran aqueous two‐phase systems

Abstract: Utilizing a modified form of the Flory-Huggins theory of polymer solution thermodynamics, a generalized expression has been obtained for correlating protein partitioning in the polyethylene glycol (PEG)/dextran aqueous two-phase systems. The expression relates the natural logarithm of the partition coefficient of the protein to the polymer concentration difference between the phases. The parameters of the relationship are a function of protein and phase forming polymer molecular weight, protein-water, protein-polymer and polymer-water interaction parameters, and the electrostatic potential difference between the phases. The relationship was verified by partitioning 17 proteins covering a wide range of molecular weight in the tie lines of the above systems, along with data from the literature. This correlation will facilitate the selection and engineering scale-up of aqueous two-phase systems for biomolecule purification.

A Collateral Effect of Reward Predicted By Matching Theory

Abstract: Matching theory describes a process by which organisms distribute their behavior between two or more concurrent schedules of reinforcement (Herrnstein, 1961). In an attempt to determine the generality of matching theory to applied settings, 2 students receiving special education were provided with academic response alternatives. Using a combined simultaneous treatments design and reversal design, unequal ratio schedules of reinforcement were varied across two academic responses. Findings indicated that both subjects allocated higher rates of responses to the richer schedule of reinforcement, although only one responded exclusively to the richer schedule. The present results lend support to a postulation that positive reinforcement may have undesirable collateral effects that are predicted by matching theory (Balsam & Bondy, 1983).

Comparison of Job Satisfaction in Six New Jersey Fisheries: Implications for Management

Abstract: New Jersey's marine fisheries exhibit unusual diversity within a small geographical area-contrasting in terms of prey species, gear size and type, trip duration, seasonality, regulatory policies, and income levels. One might expect these differences to engender different patterns of job satisfaction. Based on a survey of several hundred fishermen, the paper compares baymen, oystermen, sea clarnmers, scallopers, draggers, and longliners with respect to thirty-three components of job satisfaction. Results show significant group-group contrasts in the nonmonetary rewards derived from fishing, even though all those surveyed were clearly commercial fishermen. One implication of these findings is that different regulatory tactics should be used if and when additional regulation of the fisheries becomes necessary.

The working alliance within time-limited therapy: A case analysis.

Abstract: A travers deux etudes de cas intensives, cet article traite des alliances professionneles a travers les differentes etapes d'un traitement a orientation psychodynamique a court terme. L'analyse est realisee sur des donnees issues des perceptions de 2 patients, du therapeute, et d'un juge independant. Les implications des resultats sur l'etablissement d'un modele des processus d'evolution (des etapes) d'un traitement a court terme et sur les recherches futures sont egalement discutees

Hysteresis and Franck-Condon relaxation in insulator-semiconductor tunneling

Abstract: We analyze electron tunneling between semiconductor bands and insulator traps at a semiconductor-insulator interface in terms of a Born-Oppenheimer model. For insulator traps which exhibit large electron-phonon interactions this model predicts tunneling processes analogous to optical Franck-Condon transitions, i.e., tunneling followed by atomic relaxation at the defect. Such ideas go back to Gurney's treatment of electrolysis, but have not appeared in the current interface literature. We estimate the relaxation energies for a model of the E' center in silicon dioxide and argue that the hysteresis observed by Zvanut et al. in band-to-trap tunneling in Si-${\mathrm{SiO}}_{2}$ most likely arises from such a process, which we call hysteretic tunneling. We suggest that such processes should occur in other cases involving insulating defects which exhibit large electron-lattice coupling.

Organizational Script Development Through Interactive Accommodation

Abstract: Scripts, a type of cognitive structure that retains knowledge of events for a particular context, have been used to research recall and recognition tasks but have been largely neglected in the study of organizational settings. In this study the major focus is on the development of common scripts by organizational members for a frequently occurring organizational activity. This study demonstrates how members of a simulated, nascent organization come to adopt a set of tasks for accomplishment of a joint activity through interactive accommodation of subunit goals. Over time tasks co-evolve into a well-known pattern of events for the activity. We provide evidence of the development of organizational scripts, that is, cognitive and behavioral, across organizational members for the pattern of events associated with the activity.

EPR identification of the single-acceptor state of interstitial carbon in silicon

Abstract: An EPR center labeled Si-L6 is reported which is identified as arising from the singly ionized acceptor state of isolated interstitial carbon (${\mathrm{C}}_{\mathit{i}}^{\mathrm{\ensuremath{-}}}$) in electron-irradiated crystalline silicon. Correlated deep-level capacitance transient spectroscopy measurements locate the acceptor level at ${\mathit{E}}_{\mathit{c}}$-0.10 eV. The core structure of the defect is a 〈100〉 C-Si interstitialcy similar to that previously proposed for ${\mathrm{C}}_{\mathit{i}}^{+}$. The spin wave function is substantially more diffuse, however.

The mixed mode crack problem in a nonhomogeneous elastic medium.

Abstract: A nonhomogeneous elastic medium containing a crack arbitrarily oriented with respect to the direction of property gradient is considered. The problem is solved under plane strain or generalized plane stress conditions. This is a highly simplified version of a class of physical problems that may arise in fracture mechanics studies of ceramic coatings, metal/ceramic composites and interfacial zones with continuously varying volume fractions or graded properties. The main results of the paper are the calculated mode I and II stress intensity factors. Among the questions studied are the effects of the material nonhomogeneity constant, the crack orientation, the loading conditions and the Poisson's ratio on the stress intensity factors. The stress state near the crack tip and the crack opening displacement are also briefly discussed.

Effect of magnesia solute on surface diffusion in sapphire and the role of magnesia in the sintering of alumina

Abstract: Surface diffusion in sapphire and sintering of Al2O3 have been studied under identical firing conditions (1593°C, N2) as a function of MgO solute additions. The effect of MgO on surface diffusion has been investigated directly using the technique of multiple scratch smoothing on the (1123) surface of sapphire. For these conditions MgO additions enhance the decay of periodic profiles by a factor of 4; that is interpreted as reflecting an increase in the surface diffusivity by the same amount. Measurements of the grain sizedensity trajectory during final stages of sintering of Al2O3 reveal that MgO enhances the densification rate/coarsening rate ratio by a modest factor of 1.8. Since an increase in surface diffusivity alone would decrease the ratio, it is deduced that the primary role of MgO in the sintering of Al2O3 is other than the influence on surface diffusion. These observations in conjunction with independent measurements of the effect of MgO on grain-boundary mobility confirm that the primary role of MgO is the suppression of grainboundary motion.

A study of the off-contact screen printing process. I. Model of the printing process and some results derived from experiments

Abstract: A physical model of the screen printing process is described. Interrupted printing tests provided guiding information on the flow pattern in the paste during the deposition process. The paste flow region ahead of the squeegee was divided into three regions: the pressurization region (region I), the downward screen cross-flow region (region II), and the paste accumulation region (region III). During printing, the squeegee tip becomes deformed and its angle of attack decreases. Region I extends from the leading edge of the deformed squeegee tip to the beginning of the deformation region. As a result of pressure buildup in region I ahead of the squeegee, there is a flow of paste under the squeegee. The paste deposition process depends mainly on the flow process in region I. Analysis of experiments indicates that the squeegees used deform so that their fronts can be approximated by a wedge. The angles of hard squeegees decrease by approximately 20 degrees from the undeformed angle of 45 degrees . The corresponding angle decrease for soft squeegees is on the order of 30-40 degrees . The vertical forces acting on the squeegees were estimated to be between 60 and 47 lbf. The average speed of the paste under the squeegee, caused by the developed hydrodynamic pressure, was found to be between 0.1 and 0.2 of the squeegee speed. >

The measurement and calculation of the X‐ray spatial resolution obtained in the analytical electron microscope

Abstract: SUMMARY The X-ray microanalytical spatial resolution is determined experimentally in various analytical electron microscopes by measuring the degradation of an atomically discrete composition profile across an interphase interface in a thin-foil of Ni-Cr-Fe. The experimental spatial resolutions are then compared with calculated values. The calculated spatial resolutions are obtained by the mathematical convolution of the electron probe size with an assumed beam-broadening distribution and the single-scattering model of beam broadening. The probe size is measured directly from an image of the probe in a TEM/STEM and indirectly from dark-field signal changes resulting from scanning the probe across the edge of an MgO crystal in a dedicated STEM. This study demonstrates the applicability of the convolution technique to the calculation of the microanalytical spatial resolution obtained in the analytical electron microscope. It is demonstrated that, contrary to popular opinion, the electron probe size has a major impact on the measured spatial resolution in foils < 150 nm thick.