bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of ambient odors on slot‐machine usage in a las vegas casino
Authors: Hirsch Alan R.
Published: July 2007

Studies have shown that ambient aromas impact on consumers' behavior. To further investigate such effects, for one weekend, two slot‐machine areas in a Las Vegas casino were odorized, each with a different aroma. A third slot‐machine area served as an unodorized control. The amounts of money gambled in slot machines located in the three areas were measured and compared for the weekend of the odorization and for the weekends before and after as well, to control for extraneous variables. Our data show that the amount of money gambled in the slot machines surrounding Odorant No. 1 during the experimental weekend was greater than the amount gambled in the same area during the weekends before and after the experiment by an average of 45.11% (p = < 0.0001). Further, the amount of the increase appeared greater on Saturday when the concentration of odorant was higher: mean increase on Saturday was 53.42% (p = < 0.0001) versus mean increase on Sunday of 33.66% (p = < 0.003). The amounts of money gambled in the slot machines surrounding Odorant No. 2 and in the control area did not change significantly compared to the previous weekend and the weekend following the experiment. The likely mechanism of action of the effective odorant and the implications of these results are discussed. © 1995 John Wiley & Sons, Inc.
Ecoscale: A scale for the measurement of environmentally responsible consumers
Authors: Stone George , Barnes James H. , Montgomery Cameron
Published: July 2007

The authors develop a 31‐item instrument (ECOSCALE) for the assessment of environmental responsibility. Discussion of the conceptualization and operational functions used in constructing and refining the multiple‐item scale to measure the construct environmental responsibility are described. Also presented is evidence that the scale has been validated through assessment of content validity, predictive validity, and construct validity. A final description of the theoretical uses of such a scale is provided. © 1995 John Wiley & Sons, Inc.
Service quality and the congruency of employee perceptions and customer expectations: The case of an electric utility
Authors: Klose Allen , Finkle Todd
Published: July 2007

Understanding how the quality of customer service is impacted by employees is essential to managing and improving customer service quality. This article develops a model that looks at the relationship between a series of two important customer service gaps. The first series of gaps (service provider gaps) is a result of the difference between consumers' and employees' expectations based on various dimensions of the customer service encounter. The second series of gaps (service quality gaps) occur when a difference exists between consumer expectations and the service they actually receive based on specific aspects of the customer service encounter. This study found a positive significant relationship between these two series of gaps. This significant relationship provides empirical evidence as to the importance of keeping employees informed about the expectations of consumers. © 1995 John Wiley & Sons, Inc.
A comparative analysis of four scales of consumer involvement
Authors: Mittal Banwari
Published: July 2007

Four recent scales of consumer involvement are compared. These scales are first scrutinized, and, where necessary, modified, on a priori grounds. The modified scales are then empirically compared in terms of unidimensionality, convergent and discriminant validity, and nomological validity. On these criteria, the pruned and modified version of each of the four scales is found satisfactory. However, some unique features of each, which are discussed as trade‐offs that marketing researchers would have to consider in their choice of a scale to measure this important consumer behavior construct. © 1995 John Wiley & Sons, Inc.
The implications of interstate banking for consumers
Authors: Bennett Randall W. , Loucks Christine
Published: July 2007

The purpose of this article is to discuss the implications of interstate banking for consumers. The article describes the current structure of the banking industry, the history of legislation affecting interstate banking, and the expected effects of interstate banking on bank operating costs, availability of local funds, and concentration and competition within local banking markets as well as the anticipated effects on consumers of banking services. © 1995 John Wiley & Sons, Inc.
Marketing financial services to all levels of affluence
Authors: Verbrugge James A. , Whidbee David A. , Friedmann Roberto
Published: July 2007

This study examines efforts being made by commercial banks to satisfy their obligations under the Community Reinvestment Act while at the same time responding to changes in their economic and competitive environments. Banks are being directly and indirectly mandated by outside forces to find ways to serve all segments of their markets. What one could consider the banks' choices or prerogatives, such as served markets, selection and pursuit of desired market niches, differentiation strategies, and positioning alternatives, are all being affected by outside regulatory forces. In an effort to identify the marketing‐related factors that differentiate the two groups, this study compares the policies and characteristics of those institutions that are satisfying their regulatory obligations to those institutions that are not satisfying their obligations. © 1995 John Wiley & Sons, Inc.
Microwave and millimeter‐wave device and circuit design based on physical modeling
Authors: Snowden C. M.
Published: July 2007

The development and application of physical models for use in the design of microwave and millimeter‐wave devices and circuits is reviewed. The relative merits of physical models for a variety of active and passive devices are presented together with state‐of‐the‐art results. Particular emphasis is placed on the suitability of the models for use in computer‐aided design software. The techniques used to implement the models in linear and nonlinear designs are examined. Recent developments are presented which indicate the trend toward incorporating these types of models in future design software packages.
From static approximations to full‐wave analysis: The analysis of planar line discontinuities
Authors: Wolff Ingo
Published: July 2007

A comparison of different methods for the characterization of planar line discontinuities with emphasis on microstrip discontinuities is given, thereby describing the present state of the art in this area of microwave circuit CAD. Quasi‐static equivalent circuit models, the magnetic wall waveguide model of microstrip discontinuities, full‐wave analysis techniques like the orthogonal series expansion and mode matching techniques, the spectral domain analysis technique using roof‐top functions, and the finite‐difference time‐domain technique are described briefly and compared with respect to their numerical efficiency and their capabilities.
Radiation from microstrip circuits: An introduction
Authors: Gardiol Fred E.
Published: July 2007

Microstrips are open structures, that tend to radiate as the frequency of the signal increases within the microwave range. Radiation becomes significant in the vicinity of discontinuities, particularly when parts of the structure resonate. This situation is encountered in the design of filters, which often are arrays of radiating dipoles. When circuits are placed within metal enclosures, the radiated waves are reflected on the walls, and produce interference.

The mechanism of radiation is linked to the excitation of three kinds of waves: radiated waves, leaky waves, and surface waves. The latter remain trapped within the dielectric substrate and propagate with little attenuation (i.e., optical fibers), producing spurious coupling and diffraction.

An analysis technique originally developed for patch antennas provides a means to rigorously analyze the radiation from unenclosed microstrip circuits. It is based on a mixed potential integral equation formulation (MPIE), making use of Green's functions provided by Sommerfeld integrals, for which an exact evaluation technique was developed. The currents flowing on the circuits are expanded over a set of subsectional basis functions, and their intensities are determined by a method of moments. This approach provides both the circuit parameters (impedance or scattering matrices), and its radiation characteristics (antenna pattern). It allows one to determine the effect produced by a radiating element on another one, even when the two are not closely located with respect to one another.
A de‐embedding algorithm for electromagnetics
Authors: Rautio James C.
Published: July 2007

A “double delay” de‐embedding algorithm appropriate for electromagnetic analyses is described. This algorithm uses only two standards, a through and a double length through. By evaluating these standards, a special class of port discontinuities may be characterized and removed from the data calculated for a complete structure. Unlike related physical de‐embedding algorithms, both the characteristic impedance and the velocity of propagation of the through lines are determined. The technique described here is difficult to implement in a physical de‐embedding. The de‐embedding theory also provides a new definition of characteristic impedance, “equivalent TEM impedance,” for inhomogeneous media, such as microstrip. This new impedance exhibits a nonmonotonic dispersion which has been measured experimentally but is not seen using previous impedance definitions.
A generalized analysis method for microwave circuits with diodes
Authors: Han Liang , Wang Yunyi , Li Sifan
Published: July 2007

A generalized analysis method for nonlinear circuits composed of multiple devices, multi‐frequency excitation, and a multiport linear embedding subnetwork is proposed. An adaptable computing program is developed. The method is demonstrated by application to a microwave balanced mixer. The effect of parameter difference between two diodes on the behavior of a mixer is investigated.
Application of a simplified real‐frequency synthesis method to distributed‐element amplifier design
Authors: Soares R. , Perennec A. , Olomo Ngongo A. , Jarry P.
Published: July 2007

The simplified real‐frequency method is probably the best microwave circuit synthesis method available for the design of broadband amplifiers for electronic countermeasure (ECM) or communications applications. When applied to the design of interstage equalizers for microwave amplifiers, the procedure, contrary to classical synthesis techniques, utilizes only the measured scattering parameters of the 2‐port active device. The method thus directly includes device feedback effects, and neither ana priorichoice of matching network topology nor an analytical form of the system transfer function is necessary. In the version described in this article, the optimization process is applied simultaneously to transducer power gain, input match (VSWR), and noise figure of a multistage amplifier. A procedure for directly extracting distributed transmission line elements for matching networks is briefly described. The program FREEL is then applied to the design of 3‐stage 2‐8‐GHz and 1.15‐1.5‐GHz MESFET amplifiers in which three topologies are compared: lumped element, cascaded transmission line, and transmission line and open circuited stubs.
Design concepts of a novel microwave active filter
Authors: Moazzam M. R. , Aghvami A. H.
Published: July 2007

A novel microwave active bandpass filter structure, using a combination of microstrip line resonators and FETs, is described. The resulting filter not only produces positive gain but also has good performance regarding sharpness of skirts, rejection, and input and output return losses. Capability of constructing wider bandwidth and its superior performance at harmonic band frequencies over an end‐coupled filter structure are among advantages of this design.
Capacitance of microstrip lines on anisotropic substrate using the method of lines and finite elements
Authors: Wu Zhiqiang , Davidovitz Marat
Published: July 2007

A finite elements‐based Method of Lines is used to calculate static capacitances for microstrip line structures with layered substrates of arbitrary permittivity tensor. The problem is solved by discretizing the associated static equations in one coordinate variable using finite elements, and obtaining an analytical solution with respect to the remaining variable. Proper boundary and transition conditions are imposed. To validate the solution, comparison is made with results derived from other methods. A significant increase in numerical efficiency afforded by the presented method, relative to the conventional, fully discrete, finite element solution, is demonstrated quantitatively.
Closed‐form expressions for computer‐aided design of microstrip ring antennas
Authors: Bahl I. J. , Stuchly S. S.
Published: July 2007

This article presents closed‐form expressions for the resonant frequency and radiation characteristics of microstrip ring antennas to assist in the computer‐aided design of such antennas. Radiation fields are obtained using the vector electric potential calculated from the magnetic currents flowing along the inner and outer edges of the planar waveguide model for the microstrip ring structure. Expressions for radiated power, conductor and dielectric loss factors, resonant resistance, efficiency, and directivity are derived. The smaller the radius of curvature of the ring, the larger is the spacing between the magnetic currents flowing along the inner and outer edges and thus the radiation efficiency is higher. The effect of a dielectric layer covering the ring antenna is also included. Experimental results for the resonant frequency and the radiation patterns agree well with the theoretical predictions. © 1992 John Wiley & Sons, Inc.
Analysis of arbitrarily shaped microstrip patch antennas using the Sommerfeld formulation
Authors: Sarkar Tapan K. , Midya Pallab , Maricevic Zoran A. , Kahrizi Masoud , Rao Sadasiva M. , Djordjevic Antonije R.
Published: July 2007

Triangular patch modeling is used for analysis of arbitrarily shaped microstrip patch antennas over a single lossy dielectric medium. Since the Sommerfeld formulation is used, both the single dielectric layer (over which the microstrip patch is located) and the ground plane are considered to be infinitely wide. Typical numerical results are presented for rectangular, circular, semicircular, pentagonal, and triangular patch antennas. © 1992 John Wiley & Sons, Inc.
Transient analysis and simulation of nonuniform lossy transmission lines
Authors: Bandurski Wojciech
Published: July 2007

A new formulation of equations of the nonuniform lossy transmission line, in the form of integral equations based on the method of characteristics, has been introduced. Two methods of solution of these equations are presented, the first based on discretization of the integrals and, the second, a method of successive approximations, are presented and the results are compared. The presented integral equations of the line have interesting circuit representations and exhibit wave processes such as reflection, distortion, and attenuation. © 1992 John Wiley & Sons, Inc.
Application of singular value decomposition for integral equation procedures in MIMICAD
Authors: Thorburn Michael A. , Tripathi Vijai K.
Published: July 2007

An efficient moment method procedure which utilizes a point matching scheme together with a generalized inverse is formulated and implemented with the use of the singular value decomposition. The integral representation of Green's functions and a combination of semi‐infinite and subdomain expansion functions are used to formulate the numerical technique required to solve for the scattering parameters of planar microstrip multiports. Scattering parameters of typical microstrip discontinuities computed by utilizing this procedure are presented and compared with known published results. © 1992 John Wiley & Sons, Inc.
An efficient scheme for simulating large, passive microstrip layouts
Authors: Wu Doris I.
Published: July 2007

An efficient algorithm is presented here for simulating large, passive, microstrip layouts using a circle of influence approach with a full‐wave/integral‐equation‐based numerical solver. The procedure involves dividing the circuit into standard subcomponents or blocks and assigning a circle of influence for each block. Reiving on physical intuition, the computation of the couplings between blocks is then limited to those that fall within the circle. By adjusting the circle size, different orders of parasitic coupling can be included in the simulation process. Local junction effects from the individual blocks and the parasitic couplings between blocks that are in close physical proximity can always be taken into account. Aided by a newly developed graphical user interface, the tradeoff between computational efficiency and accuracy is examined by varying the diameter of the circle of influence. Data are presented to illustrate the effectiveness of this new approach. © 1992 John Wiley & Sons, Inc.
Numerical modeling of crossover and other junction discontinuities in two‐layer microstrip circuits
Authors: Hoorfar Ahmad , Zheng J. X. , Chang David C.
Published: July 2007

A mixed‐potential, spatial‐domain integral equation approach is used to model the coupling and junction effects when microstrip structures in two different layers of a common substrate are crossing each other. A Galerkin method, together with the so‐called pseudo‐mesh current distribution for the basis functions, is then applied to accurately characterize multiport junctions. As an example, a four‐port crossover of two microstrip transmission lines is characterized in terms of the S‐parameters. © 1992 John Wiley & Sons, Inc.
Three‐dimensional electromagnetic analysis of shielded microstrip circuits
Authors: Hill A. , Burke J. , Kottapalli K.
Published: July 2007

The spectral domain integral equation approach is employed for the characterization of passive microstrip circuits that cannot be analyzed using the traditional lumped‐circuit‐based approach. General planar and certain three‐dimensional structures such as vias and air bridges are analyzed using the presented technique. Spurious mode coupling and the effect of the microwave housing on circuit performance are also investigated. © 1992 John Wiley & Sons, Inc.
A hybrid‐mode boundary integral equation method for normal‐ and superconducting transmission lines of arbitrary cross‐section
Authors: Schroeder Werner , Wolff Ingo
Published: July 2007

A space domain Boundary Integral Equation (BIE) method for full‐wave analysis of general waveguide is presented. The method is demonstrated to be applicable to arbitrary shielded or unshielded waveguide cross‐sections ranging from optical waveguide to MMIC transmission lines. It allows for arbitrary isotropic complex media including normal (imperfect) conductors and superconductors as is demonstrated with full‐wave loss analysis of coplanar stripline and several thin‐film microstrip line configurations employing Au and YBCO conductors. An outline of the theory of the BIE method is given. The implications of nonsmooth boundary curves are considered, and special attention is given to the reliability of the method in being free of spurious solutions. © 1992 John Wiley & Sons, Inc.
Modeling of low‐noise microwave HEMTS for CAD‐oriented applications
Authors: Caddemi Alina , Sannino Mario
Published: July 2007

The simultaneous determination of noise, gain and scattering parameters through a computer‐driven noise figure measuring system allowed the rapid and accurate characterization of several samples of low noise HEMTs of the same family. From the measured parameters an equivalent circuit model representing the behavior of the typical device is extracted by means of a decomposition approach. Comparison between the model performance and the set of measured parameters of all devices are reported for the FHR 02FH (by Fujitsu). The modeling procedure is mainly oriented to the CAD of (M)MIC low noise wideband amplifiers. © 1993 John Wiley & Sons, Inc.
N‐way sectorial hybrid power divider design using boundary element method (invited article)
Authors: Miyazaki Moriyasu , Ishida Osami , Hashimoto Tsutomu
Published: July 2007

A design method of an N‐way sectorial hybrid power divider is described, using the boundary element method (BEM). Scattering parameters and current density distribution on the sectorial part are obtained by BEM analysis. Isolation among output ports is much improved by putting a resistive slot in the sectorial part and resistive sheets between the adjacent output lines. The design method is verified by the six‐way power divider, which has been developed in our laboratory. © 1993 John Wiley & Sons, Inc.
Rectangular boundary division method and its applications (invited review article)
Authors: Nakajima Masayuki , Yamashita Eikichi
Published: July 2007

The rectangular boundary division method within the quasi‐TEM wave approximation is described as an analysis method to give basic parameters for designing complicated microwave transmission lines. Analysis procedures of some practical planar transmission lines are outlined and practical techniques for numerical computations with this method are discussed. © 1993 John Wiley & Sons, Inc.
Two‐dimensional analysis of cutoff frequencies of GaAs MESFETS with various substrate conditions (invited article)
Authors: Horio Kazushige
Published: July 2007

Cutoff frequencies of GaAs MESFETs are simulated by using a model that considers impurity compensation by deep levels in the semi‐insulating (SI) substrate. For a higher acceptor density SI substrate, an achievable cutoff frequency becomes higher because the substrate current becomes smaller. Effects of introducing a p‐buffer layer are also studied in terms of dependencies on p‐layer thickness and its doping density. © 1993 John Wiley & Sons, Inc.
Cylindrical gate approach for signal and noise modeling of striped channel field‐effect transistors (invited article)
Authors: Ando Yuji , Kuzuhara Masaaki , Itoh Tomohiro
Published: July 2007

The two‐dimensional charge‐control effect to dc and rf performances is studied for striped‐channel field‐effect transistors based on the cylindrical gate approximation. The present theory explains the transconductance enhancements as well as a flat noise figure dependence on the drain current, which have been experimentally observed for striped‐channel devices. © 1993 John Wiley & Sons. Inc.
Maskless device fabrication technology using an integrated microwave CAD/CAM system (invited article)
Authors: Yamada Takashi , Nogawa Kaoru , Nishikawa Madoka , Harada Yasoo
Published: July 2007

A maskless process for MMICs using highly sensitive posi‐type EB resists was developed using our integrated microwave CAD/CAM system. The process can fabricate fine patterns with 0.1‐μm levels and align layer‐to‐layer and field‐to‐field within an accuracy below 0.05 μm (σ) using two types of alignment marks. Topography simulation of EB lithography using the Monte Carlo method was also added to the system to obtain the profiles of posi‐type single and double‐layer resist structures used for the process. The maskless process was successfully applied to an L‐band low‐noise amplifier with a 0.5‐μm gate length MESFET and reduced its TAT significantly. © 1993 John Wiley & Sons, Inc.
CAD formulas for resonant frequencies of TM01 and TM10 modes of rectangular patch antenna with superstrate
Authors: Chen Wei , Lee Kai‐Fong , Dahele Jash S. , Lee Richard Q.
Published: July 2007

Curve‐fitting formulas based on moment method results are presented for the normalized resonant frequencies of the TM01 and TM10 modes of a rectangular patch antenna covered with a superstrate. The formulas can be used for a wide range of substrate and superstrate thicknesses and permittivities. Although they are obtained by fitting data points with aspect ratio a/b = 1.5, the formulas are found to be useful for a/b between 1.3 and 1.8. Comparison with measured data is given. © 1993 John Wiley & Sons. Inc.
Computer‐aided design of probe‐fed and aperture‐coupled rectangular microstrip antennas
Authors: Saed Mohammad A.
Published: July 2007

This article describes a method for analysis and design of rectangular microstrip antennas coupled to a microstrip feed line in a two‐layer configuration using either a probe or a small aperture. The technique is based on the cavity model and, thus is numerically efficient, making it suitable for computer‐aided design. The analysis takes into account higher order modes excited underneath the patch. Analysis results were implemented in two computer programs: an analysis program and a design program based on optimization techniques. Experimental results are presented to validate this method. © 1993 John Wiley & Sons, Inc.
A CAD‐oriented approach for aperture‐coupled patch antennas
Authors: Maci S. , Borselli L. , Avitabile G. , Gentili G. Biffi , Tiberio R.
Published: July 2007

A simplified model is suggested for describing aperture‐coupled patch antennas in CAD applications. The scattering parameters of the antenna are calculated by assuming a single mode distribution for the currents on the slot and on the microstrip‐line. The coupling between the slot and the patch is represented by superimposing a contribution from a fundamental mode and that from higher order modes. The former is described by a complex eigenvalue of a cavity model with impedance walls. The latter is described by a parallel plate waveguide model, which properly accounts for the storage of reactive energy close to the slot. Numerical results are presented and compared with experiments. In particular, S‐band patches have been fabricated and tested to demonstrate the accuracy of the model. © 1993 John Wiley & Sons, Inc.
Numerical analysis of a crank‐type antenna on a dielectric substrate
Authors: Nakano Hisamatsu , Hirose Kazuhide
Published: July 2007

Crank lines on a dielectric substrate backed by a conducting plane are designed for radiation of a circularly polarized wave. The guided wavelength of the crank lines is evaluated by an iterative technique based on the numerically determined current distribution. It is found that the crank lines designed with the final guided wavelength can radiate a circularly polarized main beam in the broadside direction. The frequency responses of the radiation characteristics are also presented.
Use of the FDTD method in the design of microstrip antenna arrays
Authors: Zimmerman Martin L. , Lee Richard Q.
Published: July 2007

The finite‐difference time‐domain (FDTD) method is a widely used numerical technique for computer‐aided design (CAD) of printed antennas and arrays. This technique can accurately predict performance characteristics of complex microstrip antennas, including the effects of parasitic elements and aperture‐coupled feeds. In the case of arrays, mutual coupling effects between closely packed elements can also be modeled. This article will examine the advantages and limitations of the FDTD method for CAD of microstrip arrays. Calculated results are compared with experiment for a 3‐patch coplanar parasitic patch array.
Analysis and CAD techniques for periodic leaky‐wave printed antennas: Numerical and experimental results
Authors: Encinar José A.
Published: July 2007

Theoretical and experimental results are presented for a printed leaky‐wave antenna. Mode‐matching and EDC methods have been used to analyze the antenna and to design the prototypes. Reflection, transmission, and radiation measurements have been compared with theoretical predictions with good agreement. A CAD procedure is proposed to reduce the sidelobe level by tapering width and separation of metal strips.
Computer‐aided quasi‐static analysis of coplanar transmission lines for microwave integrated circuits using the finite difference method
Authors: Beker Benjamin , Cokkinides George J.
Published: July 2007

The finite difference method (FDM) is applied to the analysis of microwave integrated circuit (MIC) components that are based on the coplanar waveguide geometry. Effective dielectric constant, attenuation due to dielectric loss, and line impedance are calculated for open and shielded MICs as functions of transmission line dimensions and material parameters. The FDM is shown to be a practical engineering CAD tool for detailed examination of MICs having an arbitrary number of conductors and lossy dielectric layers, including field effect transistors.
Aging and overactive bladder may be associated with loss of urethral sensation in women
Authors: Kenton Kimberly , Lowenstein Lior , Simmons Jennifer , Brubaker Linda
Published: July 2007

Aims

To compare current perception thresholds (CPT) in the urethra and bladder of women with idiopathic overactive bladder to asymptomatic controls.

Methods

Women with ≥1 urge urinary incontinence (UUI) episode per week on 7‐day diary, seeking treatment for UUI underwent CPT testing using a Neurometer® CPT device (Neurotron, Inc., Baltimore, MD). Testing was done in the urethra and bladder at three frequencies 2,000, 250, and 5 Hz corresponding to A‐β, A‐δ, and C fibers, respectively. CPT values from the women with UUI were compared to CPT values from a group of control women without lower urinary tract symptoms.

Results

Forty‐eight controls without lower urinary tract symptoms and 13 women with UUI were included in the analysis. Women with UUI were significantly older (mean ± SD age 62 ± 14 and 44 ± 15,P < 0.0005) and more likely to be vaginally parous (P = 0.007) than control women. Urethral CPT at 2,000, 250, and 5 Hz were significantly higher in women with UUI than controls, while bladder CPT were not different between groups. Using logistic regression, to control for age and parity, urethral CPT at 5 Hz remained significantly higher in women with UUI than controls (P = 0.013).

Conclusion

Urethral sensation is significantly higher in older women, suggesting sensory neuropathy in the lower urinary tract increases with age and may contribute to the increase in overactive bladder seen with aging. These data reinforce the role of the urethra in lower urinary tract function. Neurourol. Urodynam. 26:981–984, 2007. © 2007 Wiley‐Liss, Inc.
The influence of N‐vinyl pyrrolidone on polymerization kinetics and thermo‐mechanical properties of crosslinked acrylate polymers
Authors: White Timothy J. , Liechty William B. , Guymon C. Allan
Published: July 2007

Polymerization of multifunctional acrylate monomers generates crosslinked polymers that are noted for their mechanical strength, thermal stability, and chemical resistance. A common reactive diluent to photopolymerizable formulations is N‐vinyl pyrrolidone (NVP), which is known to reduce the inhibition of free radical photopolymerization by atmospheric oxygen. In this work, the copolymerization behavior of NVP was examined in acrylate monomers with two to five functional groups. At concentrations as low as 2 wt %, NVP increases the polymerization rate in copolymerization with multifunctional acrylate monomer. The relative rate enhancement associated with adding NVP increases dramatically as the number of acrylate double bonds changes from two to five. The influence of NVP on polymerization kinetics is related to synergistic cross‐propagation between NVP and acrylate monomer, which becomes increasingly favorable with diffusion limitations. This synergy extends bimolecular termination into higher double bond conversion through reaction diffusion controlled termination. Copolymerizing concentrations of 5–30 DB% NVP with diacrylate or pentaacrylate monomer also increases Young's modulus and the glass transition temperature (Tg) in comparison to neat acrylate polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4062–4073, 2007
Particle Systems Characterization Using a Flat Cell Static Light Scattering Apparatus
Authors: Eliçabe Guillermo E. , Schroeder Walter F. , Frontini Gloria L. , Pettarin Valeria
Published: July 2007

In this work a light scattering apparatus for the study of heterogeneous liquid systems of evolving morphology is presented. A Fraunhofer configuration consisting of a linear array of photodiodes is used to detect the light scattered by thin samples illuminated by a He‐Ne laser light. Temperature control is available. The instrument is tested with the polymerization induced phase separation of a thermosetting polymer formulated with a divinylester resin copolymerized with styrene and modified with poly(methylmethacrylate). The system is successfully modeled as an arrangement of particles growing in size and number, and varying in composition. The ability of the experimental setup to provide results that can be quantitatively analyzed is checked using microspherical polystyrene standards. Different samples with nominal sizes of 0.5, 1 and 2 μm are used in different combinations of sample thickness and concentration. The analysis of the light scattering spectra is performed using inverse techniques to estimate the particle size distribution of the microspheres. The results agree with previous knowledge of the parameters of the samples.
The combination of antagonists of LHRH with antagonists of GHRH improves inhibition of androgen sensitive MDA‐PCa‐2b and LuCaP‐35 prostate cancers
Authors: Stangelberger Anton , Schally Andrew V. , Zarandi Marta , Heinrich Elmar , Groot Kate , Havt Alexandre , Kanashiro Celia A. , Varga Jozsef L. , Halmos Gabor
Published: July 2007

BACKGROUND

Antagonists of growth hormone‐releasing hormone (GHRH) could extend the duration of response of androgen sensitive prostate cancers to androgen deprivation.

METHODS

We investigated the effect of new GHRH antagonists MZ‐J‐7‐118 and MZ‐J‐7‐138 and luteinizing hormone‐releasing hormone (LHRH) antagonist Cetrorelix or castration on androgen sensitive MDA‐PCa‐2b and LuCaP‐35 prostate cancer models xenografted into nude mice. Animals bearing androgen‐independent LuCaP‐35V prostatic cancer model were also treated with MZ‐J‐7‐118.

RESULTS

Receptors for LHRH and GHRH were present in MDA‐PCA‐2b, LuCaP‐35, and LuCaP‐35V tumors. GHRH antagonists increased the inhibitory effect of surgical castration and LHRH antagonists on androgen sensitive MDA‐PCa‐2b and LuCaP‐35 tumors. The time to relapse of androgen‐dependent LuCaP‐35 tumors was extended by GHRH antagonists. Growth of androgen‐independent LuCaP‐35V xenografts was also significantly inhibited by MZ‐J‐7‐118. In MDA‐PCa‐2b tumors treatment with MZ‐J‐7‐118 caused a significant decrease of VEGF and Cetrorelix or its combination with MZ‐J‐7‐118 reduced EGF. The Bmax of EGF receptors was significantly reduced by Cetrorelix, MZ‐J‐7‐118 and their combination.

CONCLUSIONS

Our findings suggest that the use of a combination of antagonists of GHRH and LHRH could improve the therapy for androgen sensitive prostate cancer. Antagonists of GHRH could be also considered for treatment of androgen‐independent prostate cancers. Prostate 67: 1339–1353, 2007. © 2007 Wiley‐Liss, Inc.
Androgen‐dependent regulation of medium and long chain fatty acids uptake in prostate cancer
Authors: Pinthus Jehonathan H. , Lu Jian‐Ping , Bidaisee Laure A. , Lin Helen , Bryskine Inna , Gupta Radhey S. , Singh Gurmit
Published: July 2007

BACKGROUND

Epidemiological and experimental studies suggest that both fatty acids and androgens have a role in the development and progression of prostate cancer (PC). Plasma membrane fatty acid binding protein (FABPpm) is a transporter of medium and long chain fatty acids (MCFA and LCFA) across the plasma membrane, and is identical to the mitochondrial protein aspartate aminotransferase (mAAT) that is regulated by testosterone only in prostate epithelial cells, a site where PC initially develops. We therefore hypothesized that FABPpm is also regulated by androgens.

METHODS

We examined the effect of a synthetic androgen, R1881, and that of androgen receptor (AR) blocker, bicalutamide, on the expression of FABPpm and mAAT and on the uptake of fatty acids in the androgen‐sensitive LNCaP, androgen responsive 22rv1 and androgen‐independent CL1 human PC cells. This was done using immunofluorescence and confocal microscopy, Western blot, flow cytometry, and 3H‐oleate uptake studies.

RESULTS

Androgen supplementation increased the cellular and surface expression of FABPpm and mAAT and increased the uptake of fluorescently labeled MCFA and LCFA and that of 3H‐oleate only in PC cells that express the AR. Bicalutamide inhibited this phenomenon.

CONCLUSIONS

The uptake of MCFA and LCFA into PC cells is androgen regulated as well as the expression of FABPpm and mAAT. Prostate 67: 1330–1338, 2007. © 2007 Wiley‐Liss, Inc.
Dermcidin expression confers a survival advantage in prostate cancer cells subjected to oxidative stress or hypoxia
Authors: Stewart Grant D. , Lowrie Alastair G. , Riddick Antony C. P. , Fearon Kenneth C. H. , Habib Fouad K. , Ross James A.
Published: July 2007

BACKGROUND

Dermcidin (DCD) is a candidate survival gene in breast cancer. DCD gene expression has been identified in prostate cancer cell lines and primary prostate cancer tissue. The DCD protein is composed of proteolysis‐inducing factor‐core peptide (PIF‐CP) and the skin antimicrobial DCD‐1. The aim of this work was to: (i) establish if the DCD gene confers resistance of prostate cancer cells to hypoxia and oxidative stress; (ii) identify the component of the gene transcript responsible for this effect.

METHODS

Site‐directed mutagenesis was used to create mutant DCD vectors. PC‐3M prostate cancer cells were stably transfected with pcDNA3.1+ vectors encoding the entire DCD cDNA, mutant DCD vectors, or a control empty vector. Oxidative stress was produced using menadione, glucose oxidase, or hydrogen peroxide. Cell hypoxia was induced by incubation at 0.2% oxygen.

RESULTS

Comparison of cell growth showed a 54.5% relative‐proliferative advantage for the DCD‐transfected PC‐3M cells compared with sham‐transfected cells after 8 days of cell growth (P = 0.03). Overexpression of DCD provided upto 36% absolute survival advantage over sham‐transfected cells following induction of oxidative stress or hypoxia (P = 0.004). On exposure to hypoxia or oxidative stress PC‐3M cells overexpressing the entire DCD gene had upto 42% survival advantage over those transfectants lacking the PIF‐CP sequence (P = 0.004).

CONCLUSIONS

DCD and PIF‐CP are proliferation and survival factors in prostate cancer cells subjected to stressors found in the prostate cancer microenvironment. Thus, DCD and specifically PIF‐CP are potential targets for the treatment of prostate cancer. Prostate 67: 1308–1317, 2007. © 2007 Wiley‐Liss, Inc.
Androgen receptor‐mediated repression of novel target genes
Authors: Prescott Jennifer , Jariwala Unnati , Jia Li , Cogan Jon P. , Barski Artem , Pregizer Steve , Shen Howard C. , Arasheben Armin , Neilson Jessica J. , Frenkel Baruch , Coetzee Gerhard A.
Published: July 2007

BACKGROUND

The androgen receptor (AR) plays a pivotal role in prostate cancer (PCa) initiation and progression. To date, studies have focused disproportionately on androgen‐stimulated genes such as prostate‐specific antigen (PSA), while repressed genes have gained little attention, even though they too may be involved in regulating cell growth, differentiation, and apoptosis.

METHODS

ChIP Display was used to identify putative AR target genes in the ablation‐resistant human PCa cell line, C4‐2B. Quantitative real‐time reverse transcription‐PCR analysis was used to measure gene expression in cells subjected to dihydrotestosterone (DHT) timecourse and dose–response, as well as AR knock‐down and bicalutamide‐treatments.

RESULTS

We report on three genes, KIAA1217, CHRM1, and WBSCR28, which were newly identified in a screen for AR‐occupied regions in C4‐2B PCa cells, and which were repressed by treatment with DHT. AR knock‐down resulted in increased KIAA1217, CHRM1, and WBSCR28 mRNA, indicating that, like PSA stimulation, AR represses these three genes even in the absence of added ligand. DHT decreased KIAA1217 and CHRM1 pre‐mRNA levels, suggesting AR‐mediated transcriptional inhibition. Cycloheximide attenuated DHT‐mediated repression of CHRM1, suggesting the requirement of new protein synthesis. Furthermore, bicalutamide treatment did not mimic, but rather antagonized DHT‐mediated KIAA1217 repression. Unlike the handful of androgen‐repressed genes studied thus far, AR occupancy at KIAA1217, CHRM1, and WBSCR28 was mapped outside their respective 5′‐promoter regions.

CONCLUSIONS

Many more genes likely share AR‐mediated gene repression through distal regulatory elements. Further study of such targets and their transcriptional regulation may help explain the receptor's tumorigenicity in PCa. Prostate 67: 1371–1383, 2007. © 2007 Wiley‐Liss, Inc.
Anharmonic effects in germanium
Authors: Saravanan R. , Mohanlal S. K. , Nethaji M.
Published: July 2007

A precise X‐ray investigation is carried out to probe the lowest‐order anharmonic contribution of the atomic potential of the germanium atom. A total number of 1052 reflections (h + k + l = 4n and 4n ± 1) are precisely measured at room temperature using a spherical single crystal of germanium and using a Nonius CAD‐4 X‐ray diffractometer with crystal monochromatized MoKα radiation. A least‐square refinement program is used to refine the harmonic and anharmonic thermal parameters of the crystal. The refinement gives βGe = (−0.749 ± 1.79) × 10−16 J nm−3 with BGe = (0.528 ± 0.004) × 10−2 nm−2. The reliability index (R) amounts to 1.71% for germanium.
Matrix elements of the electron‐phonon interaction in the fourier‐based representation of a crystal potential
Authors: Novysh B. V. , Gololobov E. M. , Dorozhkin N. N.
Published: July 2007

A method for electron‐phonon matrix element calculations based on a Fourier representation of the crystal potential is presented. This method is free from a number of drawbacks inherent to the rigid muffin‐tin approximation. At the same time it is much easier realizable as compared with the first‐principle frozen‐phonon technique. The long‐range interactions, the collective character of ion displacements in phonon modes, and effects due to in‐sphere electron‐ion potential anisotropy can be easily taken into account. Non‐muffin‐tin corrections are shown to cause electron‐ion scattering selection rule variations. Interband transitions due to absorption or emission of optical phonons with q = 0 (e.g. Raman‐active Ag modes) require the inclusion of nonlinear ion displacement contributions to the matrix elements.
Properties of a high‐mobility two‐dimensional electron gas in modulation‐doped quantum well structures of GaInAs/AIInAs and GaInAs/(Ga1−xAlx)InAs heterostructures
Authors: Kraak W. , Oelze B. , Künzel M. , Bach H.‐G. , Bötiger J. , Nakov V. , Schulze D. , Gobsch G.
Published: July 2007

The electronic and magnetotransport properties of the two‐dimensional electron gas (2DEG) in MBE‐grown GaInAs/AlInAs and GaInAs/Ga1−xAlxInAs heterostructures are investigated in magnetic fields up to 12 T. The quantum oscillations of the magnetoresistivity (SdH effect) and the observation of pronounced quantum Hall effect demonstrate the existence of a high‐mobility 2DEG in the GalnAs potential well. The characteristic parameters of the electronic band structure of the 2DEG are determined and are compared with self‐consistent solutions of the coupled Poisson and Schrödinger equations. The influence of hydrostatic pressure on the magnetotransport properties is studied. A surprisingly weak change of the subband occupation with pressure is revealed.
XPS study of KTaO3, KTa0.69Nb0.31O3, and KNbO3 single crystals
Authors: Winiarski A. , Neumann T. , Mayer B. , Borstel G. , Neumann M.
Published: July 2007

XPS measurements were performed on in situ split KTaO3, KNbO3, and cubic KTa0. 69Nb0. 31O3 single crystals. The spectra are compared with the results of electronic structure calculations for the pure bulk materials in the cubic phase, based on the self‐consistent scalar‐relativistic linearized muffin‐tin orbital (LMTO) method. Comparing the experimental and calculated spectra good agreement is found. Angle‐resolved XPS experiments show distinct surface contributions to the recorded spectra, especially to the potassium peaks and in the valence band region.
The role of covalency and bridging ligands in two‐ion cooperative optical transitions in lanthanide ion‐coupled systems
Authors: Mironov V. S. , Kaminskii A. A.
Published: July 2007

The influence of covalency and bridging ligands on cooperative optical effects in dimers with closely coupled lanthanide ions in insulating crystals and binuclear complexes is theoretically treated. It is shown that there is a specific interaction between Ln3+ ions (which may be called covalent coupling) in tight ion pairs originating from virtual electron hoppings between lanthanide ions via common bridging ligands. This interaction can be regarded as a generalization of the superexchange interaction mechanism. A general microscopic model and the corresponding formalism for the covalent coupling mechanism are developed. A general expression to estimate the intensity of electric dipole two‐ion cooperative optical transitions is derived. Both the nature of bridging ligands and the local geometry of the Ln3+ (A)–ligandLn3+ (B) dimer are found to affect strongly the intensities of cooperative transitions. Our model predicts rapid increase in the contribution of this mechanism to the intensities of two‐ion transitions when going from small “ionic” ligands (F− and O2−) to large “covalent” ligands (Br−, I−). Possible manifestations of the covalent coupling mechanism in fast energy transfer processes and unusually strong up‐conversion fluorescence observed in CsCdBr3 : Ln3+ systems and as well as in electronic spectra of the U2Cl10 binuclear compound are discussed.
Frequency dependent losses in REBa2Cu3O7 (RE = Dy, Ce)
Authors: Roy D. , Deb S. K. , Neogy C. , Nag A.
Published: July 2007

Frequency dependent response of DyBa2Cu3O7 and CeBa2Cu3O7−x is measured by a simple contactless method over a wide frequency range (1 KHz to 13 MHz) at 300 and 77 K. The volume fraction of the superconducting phase can be easily estimated by the method. It is seen that χ′ (≈ −1/4π × Meissner fraction) for DyBa2Cu3O7 at 77 K is independent of frequency up to 10 MHz in the Meissner state. For CeBa2Cu3O7−x which is a non‐superconducting insulator, χ′ is positive and increases with frequency both at 300 and 77 K (χ′ (77 K) < χ′ (300 K)). The relaxation mechanism for the ac conduction in DyBa2Cu3O7 in the normal state is suggested to be primarily due to tunnelling and hopping of 2p hole polarons located at oxygen sites.
Theory of a Confinement Effect of Dipole Rotations Resulting in Saturation in Microwave Heating of Ceramics
Authors: Endicott M. R. , Kenkre V. M. , Kuś M.
Published: July 2007

Recent observations on microwave heating in ceramic materials have included saturation effects wherein the dependence of the heating rate on microwave power becomes sublinear, with a resulting decrease in efficiency relative to standard Joule heating. A model based on absorption by bivacancy rotations is shown to account for the anomalous power dependence. Rotation, by its very nature, is shown to result in an effective confinement of the dipoles and to reproduce the sublinear effect both qualitatively and quantitatively. Explicit calculations are presented for a simple model, the results are examined in the light of observations on ferric oxide, and the rotational absorber model is compared with a translational counterpart treated earlier.
Transmission Resonance Pattern in Finitely Periodic Simple Impurity Doped Superlattice Structures
Authors: Kalotas T. M. , Lee A. R. , Common A. K.
Published: July 2007

The resonance spectrum of a finitely periodic Superlattice system is analysed for the special case where each period is made up of N identical “structure” potential cells terminated by one different “impurity” cell. It is shown that the effect of the impurity is to re‐group the resonances of the corresponding “undoped” structure, in which all “impurity” cells are replaced by “structure” cells. The close relation to band splitting in the infinitely periodic limit is discussed.