bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction of 4‐benzylidene‐2‐methyl‐5‐oxazolone with amines, Part 2: Influence of substituents in para‐position in the phenyl ring and a substituent on amine nitrogen atom on the reaction kinetics
Authors: Betłakowska B. , Banecki B. , Czaplewski C. , Łankiewicz L. , Wiczk W.
Published: August 2002

An influence of a structure of the amine (benzylamine, N‐methyl‐benzylamine, N‐isopropyl‐benzylamine, N‐methyl‐butylamine, N‐ethyl‐butylamine, sec‐butylamine, and tert‐butylamine) on a rate constant of the ring‐opening reaction of 4‐benzylidene‐2‐methyl‐5‐oxazolone (Ox) was studied. The good correlation between logarithm of the rate constants and Charton's steric substituent constant ν as well as good correlation with a form of the simple branching equation indicate that there is a steric effect because of substitution at C1 carbon atom of nucleophile which decreases the reaction rate. Additionally, an influence of a structure of the benzylidene moiety of Ox on a rate of the oxazolone ring‐opening reaction was studied. The substituents (OH, OCH3, N(CH3)2, Cl, NO2) in para‐position of the phenyl ring of Ox substantially modified the rate of the reaction with benzylamine in acetonitrile. The rate of the Ox ring‐opening reaction decreased with increase of the electron‐donating properties of the substituent. A good correlation between the rate constants of the reaction of 4‐(4′‐substituted‐benzylidene)‐2‐methyl‐5‐oxazolones with benzylamine and the electron density at the reaction center (carbon C5 of the oxazolone ring), calculated using ab initio method, and the Hammett substituent constants, and CR equation were established. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 148–155, 2002; DOI 10.1002/kin.10039
Heterogeneous kinetic studies of the hydrogen peroxide decomposition with some transition metal‐heterocyclic complexes
Authors: El‐Safty S. A. , El‐Sheikh M. Y. , Salem M. A. , Zaki A. B.
Published: August 2002

The heterocyclic compounds piperidine (Pip), piperazine (Pz), morpholine (Morph), and N‐methyl piperazine (N‐MPz) were used as ligands to form transition metal complexes with Ni(II), Cu(II), and Co(II) ions. These complexes were supported on Dowex‐50W resin so as to form new potential active catalysts for H2O2 decomposition in an aqueous medium. In all cases the reaction showed a first‐order kinetics with respect to H2O2 concentration, except with Co(II) complexes, the reaction showed a second‐order kinetics with 2% divinyl benzene (DVB) (50–100 mesh and 200–400 mesh). The rate constant k (per gram dry resin) was evaluated with a resin of cross‐linkage 2 and 8% DVB (50–100 mesh) and 2% DVB (200–400 mesh) over temperature range 25–40°C. With a given resin cross‐linkage, the rate constant has the following order: Ni(II) complexes < Co(II) complexes < Cu(II) complexes. With Pz ligand, k increased in the following sequence: Ni(II) complexes < Cu(II) complexes < Co(II) complexes. The reaction mechanisms of the first‐ and second‐order kinetics were discussed and the activation parameters were deduced. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 617–624, 2001
Oilseed rape and field bean production potential on an amended former landfill site restored with London clay
Authors: Sellers G. , McRae S. G. , Cook H. F.
Published: August 2002

Re‐establishment of vegetation on landfill sites, as required in UK planning consents, frequently means establishing viable arable agriculture rather than grassland. However, there is currently little information on crop suitability or yield, especially where the land has been restored with clay subsoils.

Results are presented from three years growing oilseed rape and two years growing field beans, on a landfill site in south Essex, England, which was restored with London Clay. The site was restored in two ways. One area had a 900 mm depth of London Clay applied on top of the capped landfill. The second area had a 700 mm depth of London Clay topped with 200 mm of imported sieved material (known as screened material or ‘screenings’) which looked suitable for use as a soil forming substrate. The amendments tested were indigenous topsoil, screened material, mineral fertilizer, greenwaste compost or sewage sludge cake.

Results show that oilseed rape is not suitable. It performed poorly regardless of amendment (greatest yield = 1.1 t ha−1 or 50 per cent of average agricultural yield). Mineral fertilizer produced some small improvement with oilseed rape when grown on London Clay or with a topsoil‐forming layer of screenings. Beans performed well (greatest yield 3.9 t ha−1, comparable to average agricultural yields). Sludge cake had little effect on bean growth performance and both crops performed poorly on land amended with green waste compost. Screenings improved yield if sludge or no amendment was used, but had no effect when mineral fertilizer was applied. Copyright © 2001 John Wiley & Sons, Ltd.
Electrophysiologic effect of gallium arsenide laser on frog gastrocnemius muscle*
Authors: Comelekoglu Ulku , Bagis Selda , Buyukakilli Belgin , Sahin Gunsah , Erdogan Canan
Published: August 2002

Background and Objective

In this study, the effect of low energy Gallium arsenide (GaAs) laser irradiation on the compound action potential of frog gastrocnemius muscle were investigated.

Study Design/Materials and Methods

Sixty frogs were divided into different six dose groups: laser 1 (1 Hz), laser 2 ( 4 Hz), laser 3 (16 Hz), laser 4 (64 Hz), laser 5 (128 Hz), and laser 6 (1,000 Hz, DC, continue) (in each group n = 10). Low energy GaAs laser (wavelenght: 904 nm, pulsed duration: 220 nanoseconds, peak power per pulse: 27 W, total applied energy density: 0.001–25.7 J/cm2) was used for the experiment. Compound muscle action potentials were recorded before laser irradiation and these data were accepted as control group. After recording the control data, each muscle was irradiated by the laser. Action potentials were recorded at 1, 5, 10, 15, and 20 minutes of irradiation time in each group by using standartized needle electromyography and nerve conduction study techniques. Distal motor latency, peak to peak amplitude, area, and total duration of action potential were measured. Repeated measures analysis of variance were used for the statistical evaluation.

Results

No significant differences were detected between control and laser dose groups in muscle action potential parameters.

Conclusions

This study revealed that at the different repetition rate and exposure time, low energy GaAs laser does not have any significant effect on frog gastrocnemius action potential. Lasers Surg. Med. 30:221‐226, 2002. © 2002 Wiley‐Liss, Inc.
Planned obsolescence and marketing strategy
Authors: Utaka Atsuo
Published: August 2002

By using a two‐period model of a durable goods monopolist, we investigate marketing activities that have an obsolescence effect on products already sold in the past period. We assume that the monopolist can stimulate consumer demand for second‐period products by marketing activities, and analyse not only the case where the level of marketing is determined in the second period, but also the case where it is determined in advance, namely, in the first period. It is shown that the equilibrium level of marketing becomes higher than the efficiency level not only in the former case, but also in the latter case if the obsolescence effect is not so large. Copyright © 2000 John Wiley & Sons, Ltd.
Treatment of periodic limb movements in sleep with selegiline HCl
Authors: Grewal Manavdeep , Hawa Raed , Shapiro Colin
Published: August 2002

Thirty‐one patients undergoing treatment with selegiline HCl for periodic limb movements in sleep (PLMS) were examined with respect to specific sleep composition in a retrospective study. Pre‐ and post‐treatment overnight polysomnographs revealed a highly significant decrease in the number of PLMS per hour of total sleep time (P < 0.0005). The alerting effect associated with selegiline was not found to have significant effect on patients' sleep efficiency or sleep‐onset latency (P > 0.10). As controversy continues regarding the medicated treatment of PLMS, our findings with selegiline point to an alternative for clinicians to consider. © 2002 Movement Disorder Society
CYP2D6 polymorphism in Parkinson's disease: The Rotterdam study
Authors: Harhangi B. Sanjay , Oostra Ben A. , Heutink Peter , van Duijn Cornelia M. , Hofman Albert , Breteler Monique M.B.
Published: August 2002

The CYP2D6 polymorphism has been studied extensively in association with Parkinson's disease (PD), with no consistent results. Several explanations, such as differences in study design or bias in the selection of the control population, have been offered for these inconsistent results. We designed a case control study nested within a prospective population‐based cohort study in which cases and controls were sampled from the same source population. To assess the significance of the CYP2D6 gene in PD, we investigated two mutant alleles, CYP2D6*3 and CYP2D6*4, associated with poor metabolism and the wild type allele in 80 patients with PD and 156 matched controls, frequency matched on age and gender. No differences between cases and controls were found for the poor metabolizer genotype. However, we found that in contrast to earlier reports, the CYP2D6*4 mutant allele frequency was lower in cases as compared to controls, albeit not statistically significant. Our result supports the hypothesis that the CYP2D6 gene is not a major gene responsible for PD. © 2001 Movement Disorder Society.
Cervical dystonia severity scale reliability study
Authors: O'Brien Christopher , Brashear Allison , Cullis Paul , Truong Daniel , Molho Eric , Jenkins Stephen , Wojcieszek Joanne , O'Neil Thomas , Factor Stewart , Seeberger Lauren
Published: August 2002

Cervical dystonia (CD) is characterized by sustained contractions of the neck musculature, resulting in abnormal head postures. The Cervical Dystonia Severity Scale (CDSS) was developed to provide a reliable measure of treatment response in patients with CD. The CDSS uses a protractor and wall chart to rate the severity of the head's deviation from neutral in each of three planes of motion (rotation, laterocollis, anterocollis/retrocollis), which is then scored in 5 degree intervals (1 degree to 5 degrees deviation = 1; 86 degree to 90 degrees deviation = 18).

To test the reliability of the CDSS, four centers, each with two independent examiners, evaluated 42 patients with CD. At each site, each of the two examiners used the CDSS to evaluate the head position of each patient twice, on the same day, for a total of four evaluations. The kappa value for intra‐examiner agreement was 0.94 (95% confidence limit of 0.900–0.972), indicating excellent intra‐examiner reliability. The kappa value for interexaminer reliability was 0.79 for the first evaluation and 0.86 for the second evaluation (95% confidence limits of 0.668–0.920 and 0.790–0.920) indicating excellent interexaminer reliability. Thus, the CDSS was highly reliable in both intra‐examiner and interexaminer scoring comparisons. © 2001 Movement Disorder Society.
A subcutaneous heterotopic limb transplantation model in the mouse for prolonged allograft survival
Authors: Tung Thomas H.H. , Mohanakumar Thalachallour , Mackinnon Susan E.
Published: August 2002

A heterotopic position of a limb allograft is advantageous in the fragile mouse model to reduce mortality but is prone to autotomy. The purpose of this study was to describe a new heterotopic limb transplantation model in the mouse for prolonged allograft survival. Eleven lower hindlimbs were transplanted in a heterotopic subcutaneous position in the groin of the recipient animal with the donor skin inset as a skin paddle for monitoring. Seven transplants were syngeneic (Balb/c) and four were allogeneic (C57Bl/6 donor). The overall success rate (acute survival < 7 days) was 73% (8/11) and the mortality rate was 18% (2/11). Five of seven syngeneic transplants survived for 60 days and were harvested for histology. Recipients of successful allogeneic transplants (n = 3) received no immunosuppression and rejected their allografts between 8 and 11 days postoperatively. Mixed lymphocyte culture and flow cytometry demonstrated secondary immune responses by pre‐sensitized animals, and histology showed lymphocytic infiltration and necrosis consistent with acute rejection. © 2001 Wiley‐Liss, Inc. MICROSURGERY 21:298–305 2001
Stabilization of infinite‐dimensional second‐order system by adaptive PI‐controllers
Authors: Kobayashi Toshihiro
Published: August 2002

In this paper adaptive stabilization of infinite‐dimensional undamped second‐order systems is considered in the case where the input and output operators are collocated. The systems have an infinite number of poles and zeros on the imaginary axis. The adaptive stabilizer is constructed by an adaptive PI‐controller (proportional plus integral controller). An energy‐like function and a multiplier function are introduced and adaptive stabilization of the linear second‐order systems is analyzed. Copyright © 2001 John Wiley & Sons, Ltd.
Bounds for mixtures of an arbitrary number of materials
Authors: Barbarosie Cristian
Published: August 2002

This paper studies the problem of bounding the effective conductivity coefficients of mixtures made of several materials, in given proportions. Lower and upper bounds are obtained, and the optimality of these bounds is proven under certain hypotheses. Also, necessary and sufficient conditions for a mixture to attain the bounds are described. Some of the results were already known, but we give simpler proofs. Copyright © 2001 John Wiley & Sons, Ltd.
FIR filter design problems of simultaneous approximation of magnitude and phase and magnitude and group delay
Authors: Reemtsen Rembert
Published: August 2002

Two of the four central design problems for FIR filters in the frequency domain are the problems of simultaneous approximation of prescribed magnitude and phase responses and prescribed magnitude and group delay responses, respectively. In the past, these problems have almost always been approached in indirect and approximative ways only. Especially (approximate) solutions of the simpler frequency response approximation problem have served as substitutes for solutions of the magnitude‐phase problem. In this paper, at first a rigorous mathematical formulation of both problems is developed and then, for these problems, the existence of solutions and results on the convergence of the approximation errors are proved. (A method to solve both problems is simultaneously suggested in Görner et al. (Optimization and Engineering 2000; 1:123–154).) Also the improvement, obtained by use of a direct solution of the magnitude‐phase response problem instead of a solution of the frequency response problem, is quantified by computable bounds. In the study, the approximation errors are measured by an arbitrary Lp‐normresp. lp‐norm with 1⩽p⩽∞, and constraints on the filter coefficients are permitted. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of the radiation properties of a planar antenna on a photonic crystal substrate
Authors: Ammari Habib , Béreux Natacha , Bonnetier Eric
Published: August 2002

This paper is concerned with the rigorous investigation of the radiation properties of a planar patch antenna on a photonic crystal substrate. Under the assumptions that the driving frequency of the antenna lies within the band gap of the photonic crystal substrate and that the crystal satisfies a symmetry condition, we prove that the power radiated into the substrate decays exponentially. To do this, we reduce the radiation problem to the study of the well‐posedness of a weakly singular integral equation on the patch antenna, and to the study of the asymptotic behaviour of the corresponding Green's function. We also provide a mathematical justification of the use of a photonic crystal substrate as a perfect mirror at any incidence angle. Copyright © 2001 John Wiley & Sons, Ltd.
Asymptotic behaviour of global smooth solutionsto the multidimensional hydrodynamic model for semiconductors
Authors: Hsiao Ling , Wang Shu , Zhao Huijiang
Published: August 2002

In this paper, we study asymptotic behaviour of the global smooth solutions to the multidimensional hydrodynamic model for semiconductors. We prove that the solution of the problem converges to a stationary solution time asymptotically exponentially fast. Copyright © 2002 John Wiley & Sons, Ltd.
Optical monitoring system for wavelength‐routing networks employing array waveguide gratings
Authors: Capmany José , Pastor Daniel , Muñoz Pascual
Published: August 2002

In this letter, we propose and experimentally demonstrate a novel passive scheme for the path monitoring of wavelength‐routed networks where optical nodes are implemented by means of arrayed waveguide routers. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 319–322, 2001.
On the accuracy of the addition theorem for a scalar Green's function used in the FMM
Authors: Li Jian‐Ying , Li Le‐Wei , Ooi Ban‐Leong , Kooi Pang‐Shyan , Leong Mook‐Seng
Published: August 2002

The addition theorem for a free‐space scalar Green's function plays an important role in the fast multipole method (FMM). Therefore, both the accuracy and convergence are issues of concern in the code implementation of the FMM. In this paper, the addition theorem, when used in an unbounded Green's function, is numerically analyzed, and its accuracy is thus addressed and discussed. Specifically, the number of terms kept in the multipole expansion L is discussed in detail, and comparisons are made among the cases where difference parameters are used. A simple example applying the FMM to compute RCSs by a rectangular plate is given. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 439–442, 2001.
Truncation of finite‐element mesh for modal analysis of dielectric waveguides
Authors: Selleri S. , Vincetti L. , Zoboli M.
Published: August 2002

A new approach for mesh truncation in the finite‐element vectorial modal analysis of dielectric waveguides is presented. It is based on layers with real anisotropic permittivity and permeability tensors. The approach does not require any iterative procedure, can directly calculate many modes at the same time, and is very accurate in providing both the vectorial field distribution and the propagation constant. The resulting matrices for the eigenvalue problem are still sparse and real, thus limiting the computational effort. Mode cutoff conditions can be easily studied with high precision. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 178–182, 2002.
A novel printed microstrip window antenna for size reduction and circuit embedding
Authors: Xue Quan , Shum Kam Man , Chan Chi Hou , Luk Kwai Man
Published: August 2002

A printed microstrip window antenna is proposed in this paper. The window antenna is obtained by perforating a conventional microstrip patch antenna into a window‐like geometry. This perforation not only induces a size reduction of more than 50%, but also makes it possible for antenna and RF circuits to be integrated into a unified subsystem by embedding passive and active circuits into the windows of the antenna. The 10 dB return‐loss bandwidth of the window antenna is 1.7%, with a gain of 3.7 dBi. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 192–194, 2002.
Efficient capacitance extraction of MMIC passive components using MoM combined with discrete complex image method
Authors: Wang C. F. , Tan K. K. , Li L. W. , Kooi P. S. , Leong M. S.
Published: August 2002

This paper is devoted to the calculation of the capacitance of monolithic microwave integrated‐circuit (MMIC) passive components. The method of moments (MoM) is used to solve the integral equation for the electrostatic problem with the help of the spatial‐domain multilayered media Green's function that can be obtained using the discrete complex image method (DCIM). As an application, the capacitance of several MMIC passive components, including capacitors and interconnects, is calculated. The numerical experiments show the efficiency and accuracy of the present method. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 216–219, 2002.
Modeling of microwave devices with artificial neural networks using segmentation and finite elements
Authors: Cid Juan M. , García Jesús , Zapata Juan
Published: August 2002

The CAD of microwave devices involves extensively computing their electromagnetic response. Using segmentation and finite elements, a neural model for an arbitrary device is developed efficiently, even if the number of design parameters is high. This is made clear with an example of a transition between coaxial and rectangular waveguides. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 221–224, 2002.
Input impedance of rectangular microstrip patch antenna using artificial neural networks
Authors: Pattnaik Shyam S. , Panda Dhruba C. , Devi S.
Published: August 2002

A new method of using artificial neural networks (ANNs) for the calculation of the input impedance of rectangular microstrip patch antennas has been adopted in this paper. The results obtained using ANNs are compared with the experimental findings, theoretical values, and with the simulation results obtained using an IE3D package. The ANNs result are more in agreement with experimental findings. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 381–383, 2002.
Low‐sidelobe pattern synthesis of spherical arrays using a genetic algorithm
Authors: Chung You Chung , Haupt Randy
Published: August 2002

A genetic algorithm (GA) finds complex weights that yield low‐sidelobe levels for spherical arrays. The first example is a spherical–planar array with an initial high sidelobe of −13 dB, and which has an optimized pattern with a maximum sidelobe level of −27 dB. The second example is a spherical–circular array with an initial high sidelobe of −16 dB, and which has an optimized pattern with a maximum sidelobe level of −34 dB. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 412–414, 2002.
A broadband and thin circular microstrip antenna suitable for 1800 MHz band operation
Authors: Jan Jen‐Yea
Published: August 2002

A novel broadband design of a thin circular microstrip antenna suitable for 1800 MHz band operation is demonstrated. Due to the embedding of reactive loading and slots in the ground plane, a broadband operation with its two resonant modes centered at about 1800 MHz has been obtained. The proposed broadband design shows that an antenna bandwidth is ∼4.9 times that of a conventional circular microstrip antenna. Details of the antenna design and experimental results of the proposed antenna are presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 434–435, 2002.
A variational calculation for higher order mode cutoff frequencies of a symmetrical strip line by conformal mapping
Authors: Yang Hyunkieu , Lee Sangseol
Published: August 2002

The cutoff frequencies of higher order modes in a symmetrical strip line are calculated using the variational finite‐element method combined with conformal mapping. Conformal mapping is used to improve the modeling of the infinite transverse extents of a strip line. Then the finite‐element method is employed to solve the variational equation in the transformed finite region. Comparisons with numerical results found in the literature validate the presented method. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 449–452, 2002.
Multigrid analysis of scattering by large planar structures
Authors: Livne Oren E. , Brandt Achi , Boag Amir
Published: August 2002

Fast iterative analysis of two‐dimensional scattering by a large but finite array of perfectly conducting strips requires efficient evaluation of the electric field. We present a novel multigrid algorithm that carries out this task in CN computer operations, where C depends logarithmically on the desired accuracy in the field, and N is the number of spatial grid points. Numerical results are presented, and extensions of the algorithm are discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 454–458, 2002.
A unique lateral displacement of a Gaussian beam transmitted through a slab with negative permittivity and permeability
Authors: Kong Jin Au , Wu Bae‐Ian , Zhang Yan
Published: August 2002

This Letter demonstrates a unique negative lateral shift of a Gaussian beam transmitted through a slab with both negative permittivity and permeability, which is distinctly different from a shift caused by a regular dielectric slab. The incident beam is modeled as a tapered wave with a Gaussian spectrum. The waves inside and outside the slab are solved analytically from Maxwell's equations by matching the boundary conditions at the interfaces. It is shown that the field values in all regions can be unambiguously determined. Numerical simulations are presented and the field values as well as the power densities are computed for all regions. A dramatic negative lateral shift is observed when both ε and μ are negative. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 136–139, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10255
On analytical absorbing boundary conditions in FDTD
Authors: Yu Jihui , Li Yongming , Tai Heng‐Ming
Published: August 2002

In this Letter a new algorithm to compute the corner‐point field components of a two‐dimensional (2‐D) Mur absorbing boundary condition (ABC) in the finite‐difference–time‐domain (FDTD) method is presented. It is shown that field value calculation at the corner points of the truncation domain affects the accuracy of the FDTD. The proposed scheme overcomes the drawbacks of reflection on the truncated boundary and computation divergence that may occur when the existing scheme is used. Numerical examples are illustrated to validate the effectiveness of the proposed scheme. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 437–440, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10344
Analysis of a corrugated horn with the use of the BOR‐FDTD method
Authors: Johnson Christopher P. , Wahid Parveen
Published: August 2002

The derivation of the body‐of‐revolution finite‐difference–time‐domain (BOR‐FDTD) technique is presented and used to determine the return loss and radiation patterns of a corrugated horn. The perfectly matched layer (PML) absorbing boundary conditions are used for the computation. The source excitation is a sine‐modulated Gaussian pulse, spatially weighted with the cylindrical TE11 mode fields. The results for the return loss and radiation patterns are compared with those obtained using a commercial package based on a mode‐ matching/method‐of‐moments technique. The results show excellent agreement. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 452–457, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10348
On reflection from a half‐space with negative real permittivity and permeability
Authors: Wang Jianwei , Lakhtakia Akhlesh
Published: August 2002

The reflection of a normally incident wideband pulse by a half‐space whose permittivity and permeability obey the one‐resonance Lorentz model is calculated. The results are compared with those from frequency‐domain reflection analysis. In the spectral regime, wherein the real parts of the permittivity and the permeability are negative, as well as in small adjacent neighborhoods of that regime, the time‐domain analysis validates the conclusion that it is sufficient to ensure that the imaginary part of the refractive index is positive—regardless of the sign of the real part of the refractive index. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 465–467, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10352
Hybrid PSTD‐FDTD technique for scattering analysis
Authors: Li Qingliang , Chen Yinchao , Li C. K.
Published: August 2002

This paper employs a hybrid method that combines the pseudo‐spectral time‐domain (PSTD) algorithm and the finite‐difference–time‐domain (FDTD) method to analyze the scattering problems involving fine structures. In principle, the PSTD is applied in a direction with low‐density variation of structures but large computation volume, whereas the FDTD is used in other directions with high‐density variation and relatively small computation dimensions. In implementation of this hybrid algorithm, the pure scattered‐field formulation is utilized to introduce the incident wave, and a hybrid near‐to‐far‐zone field transform is developed for calculating the scattering width (SW) of the targets. The hybrid method is illustrated by analyzing two canonical scattering targets: a thin dielectric slab and a conductor‐backed dielectric slab. It is observed that the proposed algorithm is very accurate and efficient compared to the FDTD calculations for the same cases investigated. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 19–24, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10361
Extension of impedance matrix compression method with wavelet transform for 2‐D conducting and dielectric scattering objects due to oblique plane‐wave incidence
Authors: Yu Jin , Kishk Ahmed A.
Published: August 2002

The impedance matrix compression (IMC) technique is applied to analyze the square method–of‐moments (MoM) matrix arising from the surface integral equation for 2‐D conducting and dielectric objects with oblique plane‐wave incidence. The induced current components are processed separately by using wavelet basis functions. The comparison between cylinders with circular and square cross section is presented to show the effectiveness of IMC, which depends on the geometry of the object and the wavelet transform matrix. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 53–56, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10371
Simple equations for π‐phase‐modulated Talbot illuminator
Authors: Zhou Changhe , Xi Peng , Zhao Shuai , Liu Liren
Published: August 2002

A π‐phase‐modulated Talbot illuminator means that there is a half‐period π phase modulation in the output array. We will show that, by using the rule of regularly rearranged neighboring‐phase difference, simple equations can be derived to describe the pure‐phase distributions and the pulse‐density increased phenomena in a π‐phase‐modulated Talbot illuminator. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 49–52, 2001.
A nonuniform transmission‐line approach for modeling bends on transmission lines
Authors: Chunfei Ye , Yim Tan Soon , Erping Lee
Published: August 2002

A novel approach for modeling the discontinuities of transmission lines such as conductors with bends and varying size is proposed. The effect from the discontinuities is incorporated in the per‐unit‐length parameters of nonuniform transmission‐line equations. For canonical problems, our approach yields correct results. For a more general case, a comparison between our calculations and experimental data reported in the literature shows good general agreement. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 71–74, 2001.
An estimation of power transmission through a doubly clad optical fiber with an annular core
Authors: Choudhury P. K. , Lessard Roger A.
Published: August 2002

An estimation has been made of the distribution of power (over different modes) through the guiding region of an optical fiber with an annular core. The general expression for the power in the guiding region is derived under the use of a scalar field approximation, and the power pattern is plotted against the dimensionless core parameter for three lowest azimuthal model indexes. The analysis is rigorous in the sense that no approximation is used to determine the field functions. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 402–405, 2001.
Six‐finger Lange coupler on 3 mil GaAs substrate using multilayer MMIC technology
Authors: Bahl Inder J.
Published: August 2002

This paper presents the design and test data for six‐finger Lange couplers on a 3 mil GaAs substrate using the multilayer MMIC process. We achieved coupling of 3.3±0.5 dB, isolation greater than 20 dB, and return loss better than 15 dB over most of the 8–16 GHz frequency range. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 322–327, 2001.
Retinoid chemoprevention in patients at high risk for skin cancer*
Authors: DiGiovanna John J.
Published: August 2002

Patients who develop large numbers of skin cancers suffer increased morbidity and mortality. A high skin cancer risk can result from inherited disorders such as xeroderma pigmentosum (abnormal repair of UV‐induced DNA damage) or the nevoid basal cell carcinoma syndrome (tumor suppressor gene abnormality). The efficacy of systemic retinoid skin cancer chemoprevention was first demonstrated in these disorders. Since the mechanism of cancer prevention was not thought to involve correction of the underlying defect causing the disorder, individuals at high risk for new skin cancers from other causes may also benefit from this approach. With the success of organ transplantation, there is a growing population of transplant recipients living long, active lives who also have sustained chronic UV damage. This population is at high risk for developing aggressive squamous cell carcinomas. In this population, extensive skin involvement with human papilloma virus induced warts and actinic keratoses results in difficulty with diagnosis and monitoring for these dangerous malignancies. Patients who have received treatment with agents that cause DNA damage, such as X‐radiation, may also have a high skin cancer risk. Retinoid chemoprevention may also be of benefit in the management of selected patients with these iatrogenic conditions. This evolving therapeutic role has heightened the need for the development of new retinoids, with more efficacy and less toxicity, for cancer chemoprevention. Med. Pediatr. Oncol. 36:564–567, 2001. © 2001 Wiley‐Liss, Inc.
Epstein barr virus associated pediatric nasopharyngeal carcinoma: Its correlation with p53 and bcl‐2 expression
Authors: Preciado María Victoria , Chabay Paola A. , De Matteo Elena N. , Gismondi María Inés , Rey Guadalupe , Zubizarreta Pedro
Published: August 2002

Background

Pediatric nasopharyngeal carcinoma (NPC) is relatively rare. The Epstein Barr virus (EBV) association with the oncogenesis of NPC is well established. Apoptosis‐related proteins, p53 and bcl‐2, have also been described in adult NPC pathogenesis.

Procedure

From 1988 to 1998, 16 patients with NPC were treated at R. Gutierrez Children's Hospital and the National J.P. Garrahan Pediatric Hospital. Their median age was 12 years (range 8–20), 2 females and 14 males. The presence of p53, bcl‐2 and latent membrane protein‐1 (LMP‐1) of EBV expression was studied by immunohistochemistry and Epstein Barr encoded RNAs (EBERs) by in situ hybridization in tissue sections from formalin‐fixed, paraffin‐embedded NPC biopsies

Results

EBV presence and LMP‐1 expression in epithelial tumor cells were detected in all the biopsies studied. p53 was expressed in 13/16 NPCs, but the frequency of positive malignant cells differed from case to case, ranging from less than 25 to 100% with heterogeneous staining intensity. Bcl‐2 positive staining in tumor epithelial cells was detected in 2/16; whereas 10/16 cases showed bcl‐2 positivity in infiltrating lymphocytes.

Conclusions

Although our series is small, we conclude that the pathogenesis of pediatric NPC as a multistep process may well involve EBV infection. This leads to LMP‐1 expression and p53 overexpression in epithelial tumor cells, whereas bc‐2 seems unrelated to the development of this disorder. Med. Pediatr. Oncol. 2002;38:345–348. © 2002 Wiley‐Liss, Inc.
Modified, pulse field gradient‐enhanced inverse‐detected HOESY pulse sequence for reduction of t1 spectral artifacts
Authors: Alam Todd M. , Pedrotty Dawn M. , Boyle Timothy J.
Published: August 2002

A modified pulse field gradient (PFG)‐enhanced inverse (1H)‐detected 2D heteronuclear Overhauser effect spectroscopy (HOESY) pulse sequence is demonstrated for the acquisition of 1H–7Li heteronuclear correlations. In practice, t1 noise artifacts were observed using the original PFG‐enhanced inverse‐detected HOESY pulse sequence, which degraded the ability to detect accurately weak heteronuclear Overhauser signals. Experimentally it is shown that a simple modification of the PFG‐enhanced inverse‐detected HOESY pulse sequence greatly reduces the t1 noise that may result from variations in magnetic susceptibility, and allows improved detection of weak 1H–7Li correlations. Copyright © 2002 John Wiley & Sons, Ltd.
1H{15N} GHMQC study of 5,7‐diphenyl‐1,2,4‐triazolo[1,5‐a]pyrimidine and 1H, 13C and 15N NMR coordination shifts in Au(III) chloride complexes of 1,2,4‐triazolo[1,5‐a]pyrimidines
Authors: Szłyk Edward , Pazderski Leszek , Łakomska Iwona , Kozerski Lech , Sitkowski Jerzy
Published: August 2002

The 1H{15N} NMR spectrum of 5,7‐diphenyl‐1,2,4‐triazolo[1,5‐a]‐pyrimidine (3) was measured by GHMQC, unambiguously assigned and compared with the spectra of 1,2,4‐triazolo[1,5‐a]pyrimidine (1) and 5,7‐dimethyl‐1,2,4‐triazolo[1,5‐a]pyrimidine (2). A series of Au(III) chloride complexes of general formula AuLCl3, where L = 1, 2, 3, was synthesized and studied by 1HH{15N} GHMQC and 1H{13C} GHMBC. Low‐frequency shifts of 72–74 ppm (15N) and 5–6 ppm (13C) were observed upon complexation by Au(III) ions for the coordination site N‐3 and adjacent C‐2, C‐3a atoms, respectively. The 13C signals of C‐5, C‐6, C‐7 and the 1H resonances of H‐2, H‐6 were shifted to higher frequency. Comparison with analogous Pd(II), Pt(II) and Pt(IV) complexes revealed that in the case of Au(III) coordination the 15N shifts were relatively smaller, whereas those for 13C and 1H were larger. Copyright © 2002 John Wiley & Sons, Ltd.
Solid‐state 1H → 19F/19F → 1H CP/MAS NMR study of poly(vinylidene fluoride)
Authors: Ando Shinji , Harris Robin K. , Reinsberg Stefan A.
Published: August 2002

Solid‐state 1H → 19F and 19F → 1H cross‐polarization magic angle spinning (CP/MAS) NMR spectra have been investigated for a semicrystalline fluoropolymer, namely poly(vinylidene fluoride) (PVDF). The 1H → 19F CP/MAS spectra can be fitted by five Lorentzian functions, and the amorphous peaks were selectively observed by the DIVAM CP pulse sequences. Solid‐state spin‐lock experiments showed significant differences in T1ρF and T1ρH between the crystalline and amorphous domains, and the effective time constants, THF* and T1ρ*, which were estimated from the 1H → 19F CP curves, also clarify the difference in the strengths of dipolar interactions. Heteronuclear dipolar oscillation behaviour is observed in both standard CP and 1H → 19F inversion recovery CP (IRCP) experiments. The inverse 19F → 1H CP‐MAS and 1H → 19F CP‐drain MAS experiments gave complementary information to the standard 1H → 19F CP/MAS spectra in a manner reported in our previous papers for other fluoropolymers. The value of NF/NH (where N is a spin density) estimated from the CP‐drain curve is within experimental error equal to unity, which is consistent with the chemical structure. Copyright © 2001 John Wiley & Sons, Ltd.
Long‐range 19F–15N heteronuclear shift correlation: examination of J‐modulations associated with broad range accordion excitation
Authors: Russell David J. , Hadden Chad E. , Martin Gary E. , Krishnamurthy Krish
Published: August 2002

The first demonstrated example of 19F–15N long‐range heteronuclear shift correlation spectroscopy at natural abundance is reported. Because of the very large variation in the size of 2J(N,F) vs 3J(N,F) long‐range heteronuclear couplings, the utilization of one of the new accordion‐optimized long‐range heteronuclear shift correlations experiments is essential if all possible correlations are to be observed in a single experiment. A modified IMPEACH‐MBC pulse sequence was used in conjunction with an optimization range from 4 to 50 Hz to demonstrate the technique using a mixture of 2‐ and 3‐fluoropyridine, which had 2J(N,F) and 3J(N,F) long‐range couplings of −52 and 3.6 Hz, respectively. Because of the size of the 2J(N,F) long‐range coupling constant, a J‐modulation of the long‐range correlation response is observed in the spectrum resulting in a ‘doublet’ in F1 due to amplitude modulation. The size of the ‘doublet’ is shown to be a function of the parameter selection (t1max,Tmax,Tmin and spectral width in F1). This behavior is similar to F1 ‘skew’ associated with long‐range correlation responses in ACCORD‐HMBC spectra which has been analyzed in detail previously. Copyright © 2002 John Wiley & Sons, Ltd.
Inhibition of apoptosis in serum starved porcine embryonic fibroblasts
Authors: Lee Chang‐Kyu , Piedrahita Jorge A.
Published: August 2002

In nuclear transplantation, serum starvation is a general method to synchronize donor cells at the quiescent stage (G0) of the cell cycle. However, serum starvation during culture of mammalian cells may induce cell death, especially through apoptosis, thus contributing to the low efficiency of nuclear transplantation. This study was performed to characterize apoptosis during serum starvation and to determine the effects of apoptosis inhibitors such as a protease inhibitor [α2‐macroglobulin (MAC)] and antioxidants [N‐acetylcysteine (NAC), glutathione (GSH)] on serum starved porcine embryonic fibroblasts (PEF). PEF, collected from day 25–30 porcine fetuses, were cultured for 5 days in media containing 0.5% FBS to induce quiescence. Serum starved PEF showed typical morphology of apoptotic cells and stained for DNA fragmentation by TUNEL assay (26.7%). All apoptosis inhibitors tested in this study significantly (P < 0.05) reduced apoptosis of serum starved PEF, with antioxidants having better results (MAC: 7.4% vs. NAC: 1.0%, and GSH: 0.8%). Equally and importantly, the treatment with apoptosis inhibitors did not change the proportion of G0/G1 stage cells. Therefore, the addition of MAC and antioxidants during serum starvation of PEF reduces apoptosis of quiescent fibroblasts and may contribute to increasing the efficiency of nuclear transplantation by improving the quality of donor nuclei. Mol. Reprod. Dev. 62: 106‐112, 2002. © 2002 Wiley‐Liss, Inc.
Pyruvate utilization by mouse oocytes is influenced by meiotic status and the cumulus oophorus
Authors: Downs Stephen M. , Humpherson Peter G. , Leese Henry J.
Published: August 2002

In this study, the effects of meiotic status on the energy substrate dynamics of mouse oocyte‐cumulus cell complexes (OCCs) and denuded oocytes (DOs) have been examined. In the first series of experiments, OCCs from PMSG‐primed, immature mice were cultured in minimum essential medium in 8‐μl microdrops under a variety of conditions, and the medium and oocytes were sampled for pyruvate and glucose concentration and for meiotic status. Oocytes in control medium underwent germinal vesicle breakdown within 3 hr and the OCCs displayed a time‐dependent increase in pyruvate consumption, but the glucose concentration changed very little. Treatment with IBMX or dbcAMP, which maintained complete meiotic arrest, suppressed pyruvate consumption, but slightly more glucose was consumed than in controls. Hypoxanthine (HX) allowed up to 10% of the oocytes to resume maturation, and pyruvate and glucose consumption resembled that of control OCCs. FSH added to HX‐containing medium stimulated significant glucose consumption and pyruvate production. In general, a reciprocal relationship was observed between glucose and pyruvate consumption. When the energy substrate dynamics were compared with meiotic status of the oocytes, pyruvate consumption was associated with the maturation process. Although HX maintained oocytes in the germinal vesicle stage, the meiotic arrest was “leaky,” allowing increased pyruvate consumption. Additional experiments showed that DOs at either the prophase I or metaphase II stages consumed less pyruvate than oocytes actively engaged in meiotic maturation. DOs oxidized significantly more pyruvate than OCCs, and glycolytic metabolism of glucose lowered the oxidation rate in OCCs. Furthermore, while 5–6.2 times more pyruvate was consumed by OCCs than by DOs in the absence of glucose, oxidation did not mediate the meiosis‐inducing effect of pyruvate, since less of this substrate was oxidized by OCCs than by DOs. We conclude that meiotically active oocytes have a greater requirement for pyruvate than prophase I‐ or metaphase II‐arrested oocytes and that meiotic status can influence the metabolism not only of oocytes, but also of the OCCs. Mol. Reprod. Dev. 62: 113‐123, 2002. © 2002 Wiley‐Liss, Inc.
Cdc25C expression in meiotically competent and incompetent goat oocytes
Authors: Gall Laurence , Ruffini Sylvie , Le Bourhis Daniel , Boulesteix Claire
Published: August 2002

Change in Cdc25C expression and localization during maturation and meiotic competence acquisition was investigated in goat oocytes. Western blot analysis revealed that Cdc25C is constitutively expressed throughout meiosis in competent goat oocytes, with changes in its phosphorylation level. Cdc25C was detected at 55 and 70 kDa, representing the nonphosphorylated form and the hyperphosphorylated active form, respectively. During the G2‐M transition at meiosis resumption, Cdc25C was hyperphosphorylated as evidenced by a clear shift from 55 to 70 kDa. Okadaic acid which induced premature meiosis resumption associated with MPF activation also involved a premature shift from 55 to 70 kDa in goat competent oocytes. After artificial activation of goat oocytes, Cdc25C returned to its 55 kDa form. By indirect immunofluorescence, Cdc25C was found essentially localized in the nucleus at the germinal vesicle stage, suggesting that Cdc25C functions within the nucleus to regulate MPF activation. Concomitantly with germinal vesicle breakdown, Cdc25C was redistributed throughout the cytoplasm. The amount of Cdc25C, very low in incompetent oocytes, increased with meiosis competence acquisition. On the other hand, during oocyte growth while the expression of Cdc25C increased, its phosphorylation level increased concomitantly as well as its nuclear translocation. These results suggest that meiosis resumption needs a sufficient amount of Cdc25C which must be completely phosphorylated and nuclear and that the amount of Cdc25C may be a limiting factor for meiotic competence acquisition. We could consider that Cdc25C nuclear translocation and phosphorylation, during oocyte growth, prepare the oocytes in advance for the G2‐M phase transition occurring during meiosis resumption. Mol. Reprod. Dev. 62: 4‐12, 2002. © 2002 Wiley‐Liss, Inc.
Ran binding protein RanBP1 in zebrafish embryonic development*
Authors: Mangos Steve , Vanderbeld Barbara , Krawetz Roman , Sudol Krzysztof , Kelly Gregory M.
Published: August 2002

Ran, which functions in nucleocytoplasmic transport and mitosis, binds to and is regulated in part by RanBP1. We have identified a zebrafish RanBP1 cDNA and report that it encodes for a polypeptide of 233 amino acids with considerable similarity to human and Xenopus RanBP1, despite the fact that it is 10% longer due to an extension at its carboxy terminus. RanBP1 mRNA is present as a maternal transcript and is expressed ubiquitously throughout the developing embryo. At the protein level, RanBP1 is present at all embryonic stages. Surprisingly, the ectopic overexpression of the protein had no obvious effect on embryogenesis. Attempts were also made to down‐regulate RanBP1 activity by RNA interference. Injecting double‐stranded RNA augmented both the mortality rate and the frequency of induced defects. Specific defects accompanied by changes in RanBP1 expression were not seen, leading us to propose that RNAi is not a reliable method for deregulating the activity of constitutively expressed genes, like RanBP1, in zebrafish. Mol. Reprod. Dev. 59:235–248, 2001. © 2001 Wiley‐Liss, Inc.