bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of canine hemangiopericytomas with photodynamic therapy
Authors: McCaw Dudley L. , Payne John T. , Pope Eric R. , West Matthew K. , Tompson Robert V. , Tate Deborah
Published: August 2002

Background and Objective

Canine hemangiopericytomas are a commonly occurring neoplasm with a clinical course of recurrence after surgical removal. This study sought to evaluate Photochlor (HPPH) photodynamic therapy (HPPH‐PDT) as an adjuvant therapy to prevent recurrence of tumor after surgical removal.

Study Design/Materials and Methods

Sixteen dogs with naturally occurring hemangiopericytomas were treated with surgical removal of the tumor followed by PDT using Photochlor as the photosensitizer. Photochlor was injected intravenously at a dose of 0.3 mg/kg. Forty‐eight hours later the treatment consisted of surgical removal of the tumor followed by HPPH‐PDT.

Results

Nine dogs (56%) had recurrence of tumor from 2 to 29 (median 9) months after treatment. These results are comparable or not as good as other forms of therapy.

Conclusions

Photochlor photodynamic therapy applied after surgery appears to have no advantage over other forms of therapy in regards to preventing recurrence. Delayed wound healing and infections are problematic and make HPPH‐PDT an undesirable addition to surgery for the treatment of this tumor type. Lasers Surg. Med. 29:23–26, 2001. © 2001 Wiley‐Liss, Inc.
Comparison of argon‐laser welded and sutured repair of inferior vena cava in a canine model
Authors: Hasegawa Masahiko , Sakurai Tsunehisa , Matsushita Masahiro , Nishikimi Naomichi , Nimura Yuji , Kobayashi Miya
Published: August 2002

Background and Objective

Advantages of laser‐welded microarterial anastomoses have been reported. However, whether laser repair of large veins is advantageous is not yet known. Argon‐laser welding of inferior vena cava was therefore compared with conventional‐sutured repair.

Study Design/Materials and Methods

Twenty‐four adult mongrel dogs were used. Twelve inferior vena cavas were repaired using an argon laser and the rest using continuous sutures. Specimens were removed at 2, 8, 16, and 24 weeks after repair. Technical characteristics, cavographical findings, and results of histopathological study using light and transmission electron microscopy were compared.

Results

Procedure time did not significantly differ between the two groups. The sutured repair sites were narrower than those repaired by laser immediately after and at 2 and 24 weeks. Histologically, laser welding resulted from denaturation of collagen and mild healing occurred simultaneously with the disappearance of denatured collagen. By contrast, there was strong fibrotic reaction at sutured repair sites.

Conclusions

These findings suggest that argon‐laser repair of large veins is superior to continuous suturing. Lasers Surg. Med. 29:62–69, 2001. © 2001 Wiley‐Liss, Inc.
Case report: Holmium laser resection and lasertripsy for intravesical ureterocele with calculus
Authors: Aron Monish , Costello Anthony J.
Published: August 2002

The holmium laser has established an important role in urology, particularly in the treatment of benign prostatic hyperplasia (BPH) and urolithiasis. Its light (wavelength 2140 nm) has a high coefficient of absorption in water, such that 95% of the laser energy is absorbed in 0.5 mm of water. Thus, the majority of the laser energy is contained superficially, imparting the holmium laser with excellent cutting and tissue ablation properties. It provides sharp incision with simultaneous hemostasis. Perhaps the most significant benefit of the holmium laser is its versatility when delivered through rigid or flexible endoscopes using quartz fibers of various sizes. We present the use of this laser in the ablation of an intravesical ureterocele with calculus. Lasers Surg. Med. 29:82–84, 2001. © 2001 Wiley‐Liss, Inc.
Retention of membrane‐localized β‐catenin in cells lacking functional polycystin‐1 and tuberin
Authors: Kugoh Hiroyuki , Kleymenova Elena , Walker Cheryl Lyn
Published: August 2002

The tuberous sclerosis (TSC) 2 tumor suppressor gene encodes the protein tuberin, which has recently been shown to play a crucial role in the intracellular trafficking of polycystin‐1, the product of the polycystic kidney disease (PDK) 1 gene. PKD1 is responsible for most cases of autosomal dominant polycystic kidney disease, which has been described as “neoplasia in disguise.” Polycystin‐1 is a membrane protein localized to adherens junctions in a complex containing E‐cadherin and α‐, β‐, and γ‐catenins. To determine whether loss of membrane localization of polycystin‐1 and E‐cadherin affects the function of β‐catenin, β‐catenin localization and signaling were characterized in tuberin‐null EKT2 and ERC15 cells and in tuberin‐positive TRKE2 cells derived from polycystic, neoplastic, and normal rat kidney epithelial cells, respectively. EKT2 cells lacking tuberin because of inactivation of the Tsc2 gene fail to localize polycystin‐1 and E‐cadherin appropriately to these junctions. However, β‐catenin was retained at lateral cell membranes in both tuberin‐null and tuberin‐positive cells. Moreover, gene transcription mediated by β‐catenin T‐cell–specific transcription factor complexes showed no differences among EKT2, ERC15, and TRKE2 cells. Thus, β‐catenin was stably retained at the lateral cell membrane in tuberin‐null renal cells lacking membrane‐localized polycystin‐1 and E‐cadherin. These data suggest that, although loss of Tsc2 tumor suppressor gene function disrupts normal polycystin‐1 function and membrane localization of E‐cadherin, normal β‐catenin signaling is retained in tuberin‐null cells. © 2002 Wiley‐Liss, Inc.
A goal programming model for crew duties generation
Authors: Chu Sydney C.K.
Published: August 2002

An Erratum has been published for this article in Journal of Multi‐Criteria Decision Analysis 10(5) 2001, 285.

This paper proposes a model for the generation of daily work duties of airside crew (being bus drivers) at the Hong Kong International Airport. The results can be adopted as a good crew schedule, in the sense that it is both feasible, satisfying requirements of various work conditions, and ‘optimal’ in minimizing overtime shifts. It is formulated as a goal programme, specifically designed to cater for the manpower planning issues to handle frequent changes of flight schedules by flexibility in work patterns of driver duties. Illustrative results from an actual case study are given. Copyright © 2001 John Wiley & Sons, Ltd.
Separation of catecholamines by capillary electrophoresis using in‐run modified surfaces and covalently bonded surface coatings in capillaries
Authors: Sirén Heli , Vuorensola Katariina
Published: August 2002

The study was undertaken to improve the separation and the concentration sensitivity of catecholamines by capillary electrophoresis (CE) using laboratory‐coated capillaries. The coatings were made by adsorption using in‐run modification and by covalent bonding. The coating solutions used in‐run contained triethylamine (TEA), glycine or morpholine in acetate (pH 4.0) or phosphate buffers (pH 3.0). In the covalent bonding technique the coating was made with MAPT ((γ‐metacryloxypropyl)‐trimethoxysilane) using 1, 10, 20, 30, 40, and 50% solutions. The results obtained with the capillaries indicated that coating improved the efficiency of the CE systems in separation of the cationic catecholamines in ammonium acetate and sodium phosphate solutions. Furthermore, the analyses were more reproducible than if they were performed in bare silica capillaries. The highest plate numbers were obtained with the 1% and 50%‐MAPT coated capillaries or with 50 mM ammonium acetate–40 mM TEA electrolyte solution, although 20% and 30% MAPT‐coated capillaries gave the best resolution for the analytes. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 126–133, 2001
Treatment of dystonic clenched fist with botulinum toxin
Authors: Cordivari Carla , Misra V. Peter , Catania Santiago , Lees Andrew J.
Published: August 2002

Fourteen patients with “dystonic clenched fist” (three with Corticobasal Ganglionic Degeneration, seven with Parkinson's disease, and four with Dystonic‐Complex Regional Pain Syndrome) were treated with botulinum toxin A (BTXA, Dysport®). The muscles involved were identified by the hand posture and EMG activity recorded at rest and during active and passive flexion/extension movements of the finger and wrist. EMG was useful in distinguishing between muscle contraction and underlying contractures and to determine the dosage of BTX. All patients had some degree of flexion at the proximal metacarpophalangeal joints and required injections into the lumbricals. The response in patients depended on the severity of the deformity and the degree of contracture. All patients had significant benefit to pain, with accompanying muscle relaxation, and palmar infection, when present, was eradicated. Four patients with Parkinson's disease and one patient with Dystonia‐Complex Regional Pain Syndrome obtained functional benefit. © 2001 Movement Disorder Society.
Improvement of severe trunk spasms by bilateral high‐frequency stimulation of the motor thalamus in a patient with chorea‐acanthocytosis
Authors: Burbaud Pierre , Rougier Alain , Ferrer Xavier , Guehl Dominique , Cuny E. , Arne Pierre , Gross Ch. , Bioulac B.
Published: August 2002

We report on a patient with a severe form of chorea‐acanthocytosis, intractable to medical treatment, who benefited from bilateral high‐frequency stimulation (HFS) of the posterior ventral oral nucleus of the thalamus. The frequency of trunk spasms dramatically decreased after surgery and the clinical benefit remained stable 1 year later. However, no clear effect was observed on dysarthria nor on hypotonia, which always impaired gait. We propose that HFS of the motor thalamus is a potential treatment for choreic or truncal dystonic symptoms whenever hypotonia is not the main feature of the syndrome. © 2001 Movement Disorder Society
Inside‐out versus standard artery graft to repair a sensory nerve in rats
Authors: Rodrigues Antonio de Castro , Silva Maeli Dal Pai
Published: August 2002

It is known that a vein graft provides a good microenvironment for axon regeneration in motor peripheral nerves, but the use of artery graft for regeneration of sensory nerves is controversial. We sectioned the saphenous nerve and repaired it by using heterologous inside‐out and standard artery graft techniques in rats. After 4, 12, and 20 weeks, the graft and the distal stump were observed under electron microscopy. In each period studied, the pattern, diameters, and thickness of the myelin sheaths of the regenerated axons were measured in the graft and distal stump. There was capillary invasion in both the graft and distal stump, especially in the inside‐out artery graft group. Regenerated nerve fibers were prominent in both heterologous artery grafts 4 weeks after the surgical procedures. Conversely, in the distal stump, regenerated nerve fibers were observed only after 12 weeks. In both the inside‐out artery graft and standard artery graft, no statistical difference in the diameters and thickness of the myelinated fibers after 20 weeks was observed. © 2001 Wiley‐Liss, Inc. Microsurgery 21:102–107 2001
Functional and structural effects of GM‐1 ganglioside treatment on peripheral nerve grafting in the rat
Authors: Sobeski James K. , Kerns James M. , Safanda John F. , Shott Susan , Gonzalez Mark H.
Published: August 2002

Peripheral nerve regeneration after traumatic injury and standard repair with a nerve autograft is usually incomplete. This study tested the influence of graft vascularity and pharmacological intervention with GM‐1 ganglioside on nerve regeneration in a rat sciatic nerve model. Controls included an unoperated contralateral side and sham‐operated groups either with or without the GM‐1. During the 5 months of recovery, locomotion was tested by the sciatic function index (SFI). At killing, anesthetized animals were prepared for nerve conduction velocity (NCV) studies, followed by the wet weight of the gastrocnemius muscle (expression of atrophy), toe‐chewing (expression of lesion severity and sensory loss), and histological examination of the nerve segments. The SFI showed a slight but significant recovery for both the vascular and avascular groups (34% at 20 weeks), but when GM‐1 ganglioside treatment was included, the SFI was poor throughout (20–33%). The average NCV of the graft groups without GM‐1 was 46% to 57% of the normal nerve (52.7 m/s), whereas for the groups treated with GM‐1, it was 63% to 64% of normal; treatment of the non‐vascular graft group significantly improved recovery. A uniformly poor recovery from muscle atrophy was seen for all nerve graft groups (62–67%) compared with normal controls. The mean number of toes per foot chewed was 1.9 and 2.4 in graft groups without GM‐1 treatment and 0.9 and 1.3 in graft groups treated with GM‐1. This treatment significantly reduced both the extent and the number of animals exhibiting autotomy. The qualitative microscopic appearance of the distal nerve segment in all surgical groups was similar. We conclude that the systemic addition of GM‐1 ganglioside enhances only some aspects of regeneration in grafted nerves, possibly with a preferential effect on sensory nerve regeneration and functional recovery. © 2001 Wiley‐Liss, Inc. Microsurgery 21:108–115 2001
Electrophysiologic findings and muscle strength grading in brachioplexopathies
Authors: Tsai Yun‐An , Chuang Tien‐Yow , Yen Yu‐Shu , Huang Ming‐Chao , Lin Pei‐Hsin , Cheng Henrich
Published: August 2002

The electrophysiological evaluations and the British Medical Research Council (MRC) scale (0–5) findings of target muscles in brachioplexopathies before surgery and 1 year postsurgery were conducted. Each component of the brachial plexus was analyzed in 15 patients with injuries, among them, to 5 roots, 19 trunks, 7 cords, and 13 terminal nerves. In each of these cases, neurolysis and/or nerve transfer and/or neurotization were performed, within 3 weeks to 6 months after the injury was incurred, to ameliorate the resulting severe disabilities. The degrees of impairment were graded using a modified version of Dumitru's and Wilbourn's scale (mild: normal to slight decrease of SNAP amplitude and CMAP amplitude, and occasional denervation; moderate: profound decrease of SNAP amplitude and CMAP amplitude, constant denervation, and normal to slight decrease in motor unit recruitment; severe: absent SNAP amplitude, absent CMAP amplitude, marked denervation, and profound decrease or no volitional motor unit recruitment. mild = 1; moderate = 2; severe = 3). The motor power of the target muscles was graded through MRC scores. The presurgical versus postsurgical differences in the severity of the injury to each brachial plexus component, and differences in the grading of target muscle power, were calculated through the Wilcoxon signed‐rank test. The presurgical degrees of the severity of injury, as measured by the electromyography (EMG) were 3.00 ± 0.00 (mean ± SD) in root, 2.84 ± 0.50 in trunk, 3.00 ± 0.00 in cord, and 2.85 ± 0.38 in terminal nerves. The postsurgical results were 2.60 ± 0.55 in root, 2.53 ± 0.70 in trunk, 2.43 ± 0.53 in cord, and 1.77 ± 0.73 in terminal nerves. There was significant improvement at the trunk, cord, and terminal nerve levels after repair, but not at the root levels. Moreover, although the MRC grading showed significant motor recovery in the infraspinatus, deltoid, biceps, and triceps muscles, there was little apparent improvement in the pectoralis major, EDC, APB, and ADM muscles. Nerve repair was notably successful in all plexuses except at the root level. However, our cases demonstrated only poor motor power gains in the forearm and the hand muscles. Consequently, future surgical techniques for brachioplexopathy repairs need further improvement. © 2002 John Wiley & Sons, Inc. MICROSURGERY 22:11–15, 2002 DOI 10.1002/micr.22001
Numerical analysis of a non‐singular boundary integral method: Part II: The general case
Authors: Dreyfuss P. , Rappaz J.
Published: August 2002

In order to numerically solve the interior and the exterior Dirichlet problems for the Laplacian operator, we have presented in a previous paper a method which consists in inverting, on a finite element space, a non‐singular integral operator for circular domains. This operator was described as a geometrical perturbation of the Steklov operator, and we have precisely defined the relation between the geometrical perturbation and the dimension of the finite element space, in order to obtain a stable and convergent scheme in which there are non‐singular integrals. We have also presented another point of view under which the method can be considered as a special quadrature formula method for the standard piecewise linear Galerkin approximation of the weakly singular single‐layer potential.

In the present paper, we extend the results given in the previous paper to more general cases for which the Laplace problem is set on any 𝒞∞ domains. We prove that the properties of stability and convergence remain valid. Copyright © 2002 John Wiley & Sons, Ltd.
A broadband probe‐fed planar patch antenna with a short probe pin and a conducting cylinder transition
Authors: Chang Fa‐Shian , Wong Kin‐Lu
Published: August 2002

Broadband operation of a probe‐fed planar patch antenna with a short probe pin and a conducting cylinder transition is demonstrated. With the proposed feed design, the impedance bandwidth of a planar patch antenna with a thick air–layer substrate can be significantly enhanced. Prototypes of the proposed antenna with an impedance bandwidth (1 : 1.15 VSWR) suitable for applications in DCS cellular system (1710–1880 MHz) base station have been successfully constructed and studied. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 282–284, 2001.
Small‐size probe‐fed notched patch antenna with a shorting post
Authors: Shackelford A. K. , Leong S. Y. , Lee K. F.
Published: August 2002

Simulation results for a small‐size probe‐fed notched patch antenna with a shorting post are presented. The area of the patch has been reduced by 94%, while the antenna maintains a bandwidth of 13.2%. The antenna can be designed to operate in the dual‐band mode. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 377–379, 2001.
FDTD and optimization approach to time‐domain inversing problem for underground multiple objects
Authors: Guangyou Fang
Published: August 2002

The reconstruction of the parameters of underground targets is still highly anticipated in ground‐penetrating radar (GPR) applications. In this paper, the FDTD method and time‐domain optimization algorithm are used to reconstruct the permittivities of underground multiple targets. An iterative optimization algorithm is proposed. The forward scattering data are also calculated by a 2.5‐D–FDTD algorithm in order to better simulate the practical GPR situation. The relationship between the convergence rates of the inverse algorithm and the initialization values are studied. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 384–387, 2001.
Further comments on “Returning to the Post Constraints”
Authors: Lakhtakia Akhlesh , Weiglhofer Werner S.
Published: August 2002

Three clarifications are provided with respect to certain statements of Dmitriev [Microwave Opt Technol Lett 29 (2001) 363–366]. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 402–402, 2001.
An accurate 2‐D model for transconductance‐to‐current ratio and drain conductance of vertical surrounding‐gate (VSG) MOSFETs for microwave circuit applications
Authors: Kranti Abhinav , Rashmi  , Haldar S. , Gupta R. S.
Published: August 2002

An accurate analytical model for the transconductance‐to‐current ratio (gm/Ids), current–voltage characteristics, and drain conductance is developed for a vertical surrounding‐gate (VSG) MOSFET based on the solution of the 2‐D Poisson's equation. The dependence of gm/Ids, drain current, and drain conductance on key technological parameters has been analyzed in detail. A design rule to select the device parameters to enhance gm/Ids is proposed. Results show that higher values of gm/Ids can be achieved in VSG MOSFETs as compared to DG MOSFETs. Close agreement with simulated results confirms the validity of the present model. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 415–421, 2001.
Condition for chiral material parameters revisited
Authors: Sihvola Ari
Published: August 2002

The limitations for the electromagnetic material parameters of chiral media are discussed. Especially, the conditions for the imaginary part of the material parameters are under study. Physical reasons are given to support the limitation $|\kappa ''| < \sqrt{\epsilon '' \mu ''}$ for passive, isotropic chiral media. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 423–426, 2001.
Time‐domain electric‐field integral equation with central finite difference
Authors: Jung Baek Ho , Sarkar Tapan Kumar
Published: August 2002

In this paper, we present a new formulation using the time‐domain electric‐field integral equation (TD–EFIE) to obtain a transient scattering response from arbitrarily shaped conducting bodies. The time derivative of the magnetic vector potential is approximated with a central finite difference, and the scalar potential is time averaged by dividing it into two terms. This approach with an implicit method using central‐difference results in accurate and stable transient scattering responses from conducting objects. Detailed mathematical steps are included, and several numerical results are presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 429–435, 2001.
Weak guidance analysis of the modal characteristics and waveguide dispersion of a new lightguide with a lemniscate of Bernoulli‐type core cross section
Authors: Singh Vivek , Prasad B. , Ojha S. P.
Published: August 2002

The purpose of this paper is to introduce a simple analytical technique based on scalar‐wave approximation to study the modal characteristics of a new lightguide having a lemniscate of Bernoulli‐type core cross section. This type of structure may be conceived as a practical situation wherein two cores are embedded in a common cladding. Using lemniscate cylindrical coordinates (ξ, η, z) and the weak guidance boundary conditions, the eigenvalue equation is derived. From this equation, the characteristic curves have been obtained and plotted for some low‐order modes (ν=0). Furthermore, denoting the normalized frequency parameter as ν and the normalized propagation constant as b′, the variation (d(Vb′)/dV) is also obtained and analyzed. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 211–216, 2002.
A dual‐polarized L‐probe microstrip patch antenna array
Authors: Wong H. , Luk K. M.
Published: August 2002

Using L‐probe patch antennas as elements, a dual‐polarized antenna array is designed and tested. The antenna is designed for operation at 900 MHz, and is built as a two‐element linear array with a coaxial feed. The feeding network is an air transmission line which is made of aluminum. An impedance bandwidth of 24% (SWR ≤2) is obtained. The isolation is less than 25 dB across the passband, and an average gain of 10 dBi is achieved. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 235–237, 2002.
The limitations of the perfectly matched layers based on E–H fields for arbitrary anisotropic media—Reply to “Comment on ‘On the Matching Conditions of Different PML Schemes Applied to Multilayer Isotropic Dielectric Media’”
Authors: Zhao An Ping
Published: August 2002

The aim of this communication is to correct potential misunderstandings about the PMLs (which are called the MIPMLs) based on D–H (E–B or D–B) fields. In fact, the motivation for developing the MIPMLs is to establish accurate and efficient PML absorbers for general anisotropic media. It is demonstrated that, by comparing the formulations of material‐independent PML absorbers based on E–H and D–H fields (as an example) for arbitrary anisotropic dielectric media, the PMLs based on D–H fields are more accurate and efficient than those based on E–H fields. It is also demonstrated that, for arbitrary anisotropic dielectric media, the formulations based on D–H fields can be easily connected to the alternating direction implicit (ADI) FDTD method, but the formulations based on E–H fields cannot. This certainly indicates that formulations based on E–H fields have limitations for general anisotropic dielectric (and/or magnetic) media, and using the formulations based on D–H (E–B or D–B) fields is the optimal choice for such media. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 237–241, 2002.
Time‐domain finite‐element simulation of cavity‐backed microstrip patch antennas
Authors: Jiao Dan , Jin Jian‐Ming
Published: August 2002

A time‐domain finite‐element method (TDFEM) is presented for simulating the radiation and scattering from cavity‐backed microstrip patch antennas. The perfectly matched layer (PML) is utilized to efficiently truncate the TDFEM solution domain. The higher order vector basis functions are adopted to accurately represent unknown fields. Numerical examples are given to demonstrate its efficacy. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 251–254, 2002.
Influence of hard corrugated PBG wall design on performance of conical horn antenna
Authors: Skobelev Sergei , Kildal Per‐Simon
Published: August 2002

Some numerical results for a conical horn with three modifications of a hard corrugated PBG wall are presented. It is shown that a completely corrugated horn of diameter 4–5 wavelengths provides 80–87% aperture efficiency and a cross‐polar level below −30 dB for a horn length greater than 20 wavelengths. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 265–268, 2002.
Simulation of beam propagation in second‐order nonlinear optical media
Authors: Furati K. M. , Alsunaidi M. A. , Masoudi H. M.
Published: August 2002

Second‐order nonlinearity in optical media acts as a source for harmonics generation. We set up a time‐domain model that accounts not only for the second harmonic, but also for the higher harmonics that are induced by a beam propagation. The model is solved numerically using a second‐order explicit scheme based on the exact solution of the nonlinear difference equation. The power spectrum of the generated harmonics is also presented. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 312–316, 2002.
A broadband very‐high‐permittivity dielectric resonator antenna for WLAN application in the 5.2 GHz band
Authors: Hsiao Fu‐Ren , Kuo Jieh‐Sen , Chiou Tzung‐Wern , Wong Kin‐Lu
Published: August 2002

A novel broadband design of square‐disk dielectric resonator (DR) antennas with a very high relative permittivity of 90.5 is presented. Broadband operation is achieved by loading two narrow conducting strips of suitable lengths, which results in dual‐resonance excitation and leads to a wider operating bandwidth. A constructed prototype designed in the 5.2 GHz band (5150–5350 MHz) for WLAN application, having a cross section of 10×10 mm2 and a height of 1.9 mm only, shows an impedance bandwidth of 250 MHz covering the required WLAN bandwidth. Good broadside radiation characteristics with a peak antenna gain of about 4.1 dBi have also been obtained. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 426–427, 2002.
MNM‐A novel technique for iterative solution of matrix equation arising in the method‐of‐moments formulation
Authors: Mittra Raj , Prakash V. V. S. , Ma Ji‐Fu , Yeo Junho , Huang Neng‐Tien , Kwon Soon Jae
Published: August 2002

This article introduces a simple and efficient technique for generating the initial guess for iterative solutions of a large dense system of linear equations arising in the method‐of‐moments (MoM) formulation of electromagnetic (EM) problems. The proposed approach is based on an extrapolation of the solution vector from those generated at previous frequencies. The extrapolated solution is further refined, if required, by using the conjugate gradient (CG) technique. Questions regarding the accuracy of the solution, as well as its dependency on the stopping criterion and the frequency step size, have been investigated for a large class of EM problems, and representative results are presented. The superiority of the present technique over existing approaches for generating the initial estimate of the solution is demonstrated. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 74–78, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10243
A comparison of different approaches for the simulation of nonlinear transmission lines
Authors: Fernández M. , Martín F. , Steenson P. , Mélique X. , Oistein A. , Oriols X. , Vanbésien O. , García‐García J. , Miles R. , Lippens D.
Published: August 2002

In this work, a detailed analysis of two different approaches to the simulation of nonlinear transmission lines (NLTLs) is presented. Distributed and lumped‐element models have been compared, and it has been shown that the latter (and simpler) approach provides a good description of NLTL behavior when the per‐section capacitance of the line is smaller than the lumped nonlinear capacitance. Filtering aspects of NLTLs under large‐signal driving conditions have been studied with the use of a harmonic balance simulation that avoids the need to linearize the circuit. This is the first time that this powerful simulation tool has been used to study the transmission properties of NLTLs. The results are compared to those obtained by means of a conventional small‐signal S‐parameter simulation and effects related to large‐signal driving conditions, such as the influence of the input power level and the degree of nonlinearity, are presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 134–136, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10253
Detection of targets in continuous random media: A numerical study using the angular correlation function
Authors: Moss C. D. , Teixeira F. L. , Kong J. A.
Published: August 2002

A three‐dimensional (3D) finite‐difference–time‐domain (FDTD) scheme is used to study the angular correlation function (ACF) of the scattered fields from continuous random media (volume) with and without a target object present. The FDTD simulations are employed to examine the effectiveness of ACF for object detection in the presence of volumetric clutter. It is shown that the frequency‐averaged ACF can be as much as 10‐dB greater when a target object is present for situations where the target is undetectable by direct examination of the radar cross section only. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 242–247, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10287
Design of an ultraviolet filter based on photonic band‐gap materials
Authors: Srivastava Sanjeev K. , Ojha S. P. , Ramesh K. S.
Published: August 2002

The fabrication of a bandpass filter in the ultraviolet region of the electromagnetic spectrum with the use of photonic band‐gap (PBG) materials is presented on the basis of the Kronig–Penny model in the band theory of solids. The periodic structure of different dielectrics and semiconductor materials in rectangular symmetry is considered. Illustrative diagrams are presented in order of allowed and forbidden bands of wavelengths. The filter can also act as an efficient ultraviolet monochromator by the appropriate selection of the controlling parameters. The anomalous dispersion behavior of glass and zinc sulphide (ZnS) is discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 308–314, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10304
Highly efficient finite‐difference schemes for structures of nonrectangular cross‐section
Authors: Djurdjevic D. Z. , Sewell P. , Benson T. M. , Vukovic A.
Published: August 2002

A novel finite‐difference beam‐propagation method (FD‐BPM) algorithm for the analysis of photonics structures with sloped sides in the transverse plane is presented. By introducing nonorthogonal coordinate systems in the transverse plane, the staircasing effects inherent when one is modeling with a rectangular mesh are eliminated, and accuracy is substantially improved. The algorithm is tested in the analysis of sloped rib waveguides. The results obtained confirm the accuracy and high efficiency of the new algorithm. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 401–407, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10335
New‐configuration wideband single‐axis and dual‐axis planar monopulse comparators
Authors: Revankar U. K. , Beenamole K. S.
Published: August 2002

Novel configurations of single‐axis and two‐axis planar monopulse comparators are presented, providing a very close amplitude and phase matching over a wide bandwidth with an application in broadband monopulse radar systems. Unlike the conventional monopulse comparators, the present unique design features have offered a very good return loss as well as amplitude and phase imbalance of ± 0.1 dB and ± 1.5° over a large bandwidth (>15%) in L band, for two‐axis monopulse comparators. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 427–430, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10341
A new type of slow‐wave 1‐D PBG microstrip structure without etching in the ground plane for filter and other applications
Authors: Nesic Dusan
Published: August 2002

A new type of one‐dimensional (1D) photonic bandgap (PBG) microstrip slow‐wave structure applied for filter is presented. The proposed filter exhibits remarkable slow‐wave and low‐pass characteristics. It is formed without etching in the ground plane, only by modification of the microstrip line. The miniature low‐pass filter with three cells is simulated, realized, and measured. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 440–443, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10345
Reflection and transmission ellipsometry data analysis for measuring the complex permittivity of a single‐layer material at microwave frequencies
Authors: Sagnard F. , Seetharamdoo D. , Le Glaunec V.
Published: August 2002

For in situ measurement of the complex permittivity of planar materials, a free‐space system based on reflection or transmission ellipsometry has been developed and extended to microwave frequencies. Different angles of incidence were studied in the range [35–50°]. Original numerical methods based on contour‐line charts and least‐square optimization have been developed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 443–448, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10346
Electromagnetic‐wave diffraction by a chiral layer with a reflecting grating of dielectric‐filled grooves
Authors: Kusaykin Oleksandr P. , Poyedynchuk Anatoly Ye.
Published: August 2002

A diffraction problem is solved for a plane E‐ or H‐polarized wave incident on a chiral layer placed over a reflecting grating of rectangular grooves cut in a perfectly conducting metal plane. The approach uses decomposition and generalized scattering matrix methods. The phenomenon of quasi‐complete cross‐polarization conversion of waves with large telescopicity coefficient is shown. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 462–465, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10351
A new instantaneous model of MESFET and HEMT devices for large‐signal circuit design
Authors: Cicolani Maurizio , Di Martino Alberto , D'Innocenzo Silvio , Pisa Stefano , Tommasino Pasquale , Trifiletti Alessandro
Published: August 2002

A nonlinear lumped‐element model of MESFET and HEMT devices whose parameters are empirical functions of instantaneous voltages at the controlling internal nodes has been developed and used to design an X‐band hybrid amplifier. Excellent agreement between measurements and simulated performance in small‐signal and nonlinear power characteristics has been obtained. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 187–190, 2001.
Large‐signal modulation response of 1.3 μm InGaAsP MQW lasers
Authors: Torres Pereira J. M.
Published: August 2002

The large‐signal modulation response of a 1.3 μm InGaAsP four‐well laser of the Fabry–Perot type is investigated when the input signal is either a sinusoidal or a square wave. The time evolution of the photon density is obtained by the numerical solution of the rate equations for several amplitude and frequency values of the input signal. The output photon density is very similar for the two input signal types, except at low frequencies. The normalized resonance frequency is seen to behave better when the input signal is sinusoidal and nonlinear gain saturation effects take place. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 375–378, 2001.
10 GHz GaAs monolithic twin‐dipole antenna FET mixer
Authors: Meng C. C. , Deng K. L. , Lee H. D. , Lu S. S. , Wang H.
Published: August 2002

The first fully monolithic X‐band twin‐dipole antenna mixer consisting of a uniplanar twin‐dipole antenna and a GaAs MESFET single‐gate mixer on the same GaAs substrate fabricated by monolithic microwave integrated‐circuit technology (MMIC) is reported. The total chip size is 5×5 mm2. This circuit received an RF signal of 10 GHz, and down‐converted it to an IF signal of 1 GHz with a conversion loss of 22 dB. The experimental results demonstrate that this topology has potential applications for future low‐cost millimeter‐wave receivers for smart munitions seekers and automotive‐collision‐avoidance radars. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 436–438, 2001.
Frequency‐selective loading for a transmitting active integrated antenna
Authors: Ertürk V. B. , Rojas R. G. , Roblin P.
Published: August 2002

A simple frequency‐selective load in the form of a compensating network is attached to an oscillator‐type transmitting active integrated antenna (AIA) to suppress undesired low‐frequency oscillations and to improve the robustness of the oscillator. Although the input impedance of the active device (transistor) remains unchanged at the upper frequencies, it changes drastically at the lower frequencies. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 3–5, 2001.
Operating wavelength of erbium‐doped fiber‐ring laser
Authors: Kamil Abd‐Rahman M. , Selvakennedy S. , Poopalan P. , Ahmad Harith
Published: August 2002

The erbium‐doped fiber ring laser (EDFL) exhibits a wavelength shift that results from the variation of its intracavity parameters, namely, the output‐coupler reflectivity (R), active fiber length (L), and optical losses (α) in the resonant cavity. A simple and fast technique for predicting the operating wavelength of an EDFL is deduced. The operating wavelength shifts from ∼1530 to ∼1560 nm for higher values of R, longer L, and/or lower α, and vice versa. Data from numerical simulations show a good comparison with the experimental results. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 105–107, 2001.
A novel interpretation of transducer power gain by optical analogy
Authors: Pan Hsuan‐Yu , Tu Hsing‐Yuan , Lu Shey‐Shi , Meng C. C.
Published: August 2002

A novel interpretation of transducer power gain (GT) is presented by optical analogy. By employing scattering parameters of the input/output matching network and the transistor, we have developed a simple method to derive GT. In addition to simplicity, our theory also has the advantage of giving the physical meaning for each term of the formula of GT. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 124–126, 2001.
Improvement of modulation/switching performances by using a two‐section semiconductor optical amplifier
Authors: Li Hong Wu , Rampone Thierry , Guegan Mikael
Published: August 2002

By optimizing the carrier distribution along the longitudinal axis of a two‐section semiconductor optical amplifier (SOA), we have improved the modulation/switching performances (modulation index and efficiency, switching contrast) with respect to those of a single‐section component. The modulation efficiency has been raised by up to 137%. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 126–129, 2001.
BW media—media with negative parameters, capable of supporting backward waves
Authors: Lindell I. V. , Tretyakov S. A. , Nikoskinen K. I. , Ilvonen S.
Published: August 2002

Both isotropic and uniaxially anisotropic media capable of supporting backward waves are reviewed. Such an effect recently has been of great interest, and certain man‐made composite media have been introduced under the names “media with negative refraction factor” or “left‐handed materials,” effective in a certain band of microwaves. Neither of these names appears to be well founded, and “backward‐wave medium” (or BW medium) is suggested instead. It is shown that, at an interface of a regular and a BW medium, Snell's law does not imply a negative refraction factor. However, the refraction is anomalous in the sense that the transmitted plane wave is a backward wave with a Poynting vector and a wave vector pointing in opposite lateral directions. The significance of the Zenneck wave and guided modes in a cylindrical guide made of BW medium is discussed. Finally, the BW property is extended to uniaxially anisotropic media, and its occurrence is studied for different value combinations of its medium parameters. It is shown that a lateral backward wave can arise when a plane wave is transmitted through an interface when one of the four parameters of the uniaxial medium is negative. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 129–133, 2001.
Analysis of a circular chiral ferrite dielectric waveguide
Authors: Zhou Haixin , Zhang Keqian
Published: August 2002

The eigenequation of a circular chiral ferrite dielectric waveguide is derived. The effects of chiralities in the core and cladding on the cutoff, the dispersion characteristics, and the field distributions are investigated. The results show that, not only the cutoff frequencies, but also the dispersion curves of HE and EH modes with the same mode number separate, and the chiralities in the core and cladding have different effects on the cutoff and dispersion characteristics. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 143–146, 2001.
Lumbar puncture in pediatric oncology: Conscious sedation vs. general anesthesia
Authors: Ljungman Gustaf , Gordh Torsten , Sörensen Stefan , Kreuger Anders
Published: August 2002

Background

Lumbar punctures (LP) generally have been performed with conscious sedation (CS) but are increasingly performed using general anesthesia (GA) owing to the belief that this is less distressing. The aim of this study was to compare these two methods concerning distress, discomfort, pain, well‐being and security after the LP, and problems with the LP.

Procedure

Twenty‐five children with cancer participated in this prospective, randomized, crossover study. Children, parents, and nurses completed a visual analogue scale questionnaire to evaluate the efficacy of CS and GA. In addition, sedation and anesthesia protocols were reviewed.

Results

The two methods seemed to be equivalent concerning distress, discomfort, pain, well‐being and security after the procedure, and procedure problems. Most children (80%), parents (66%), and nurses (58%) preferred LP in CS. However, the LP was not performed in CS in five cases because the child did not cooperate. Younger children less often preferred CS.

Conclusions

Outcomes for CS and GA in LP were similar. Although there were failures with the CS model, most preferred it to GA. LP in CS also saved time and medical resources. An alternative approach would be to have a pediatric anesthesiologist available at the oncology ward for these elective LPs to provide the sedation or anesthesia required by each individual. Med. Pediatr. Oncol. 36:372–379, 2001. © 2001 Wiley‐Liss, Inc.
Screening for Wilms tumor and hepatoblastoma in children with Beckwith‐Wiedemann syndromes: A cost‐effective model*
Authors: McNeil D. Elizabeth , Brown Martin , Ching Alex , DeBaun Michael R.
Published: August 2002

Background

We undertook a cost‐benefit analysis of screening for Wilms tumor and hepatoblastoma in children with Beckwith‐Wiedemann syndrome (BWS), a known cancer predisposition syndrome. The purpose of this analysis was twofold: first, to assess whether screening in children with BWS has the potential to be cost‐effective; second, if screening appears to be cost‐effective, to determine which parameters would be most important to assess if a screening trial were initiated.

Procedures

We used data from the BWS registry at the National Cancer Institute, the National Wilms Tumor Study (NWTS), and large published series to model events for two hypothetical cohorts of 1,000 infants born with BWS. One hypothetical cohort was screened for cancer until a predetermined age, representing the base case. The other cohort was unscreened. For our base case, we assumed: (a) sonography examinations three times yearly (triannually) from birth until 7 years of age; (b) screening would result in one stage shift downward at diagnosis for Wilms tumor and hepatoblastoma; (c) 100% sensitivity and 95% specificity for detecting clinical stage I Wilms tumor and hepatoblastoma; (d) a 3% discount rate; (e) a false positive result cost of $402. We estimated mortality rates based on published Wilms tumor and hepatoblastoma stage specific survival.

Results

Using the base case, screening a child with BWS from birth until 4 years of age results in a cost per life year saved of $9,642 while continuing until 7 years of age results in a cost per life‐year saved of $14,740. When variables such as cost of screening examination, discount rate, and effectiveness of screening were varied based on high and low estimates, the incremental cost per life‐year saved for screening up until age four remained comparable to acceptable population based cancer screening ranges (< $50,000 per life year saved).

Conclusions

Under our model's assumptions, abdominal sonography examinations in children with BWS represent a reasonable strategy for a cancer screening program. A cancer screening trial is warranted to determine if, when, and how often children with BWS should be screened and to determine cost‐effectiveness in clinical practice. Med Pediatr Oncol 2001;37:349–356. Published 2001 Wiley‐Liss, Inc.
Temperature dependence of proton–proton residual dipolar couplings in adenosine dissolved in charged phospholipid bicelles. Application of a two‐dimensional selective refocusing method
Authors: Krajewski Piotr , Bardet Michel
Published: August 2002

1H NMR spectra of nucleoside adenosine were recorded in 7.5% (w/v) DMPC/DHPC bicelles doped with CTAB. Despite the small size of adenosine in comparison with the distances between discoidal bicelles, intramolecular 1H,1H residual dipolar couplings D were observed at 29.5–38°C. The absolute values of 1H,1H spin interactions Δ (sum of J‐ and D‐couplings) were measured selectively by a series of 2D SERF experiments as a function of temperature. At lower temperatures dipolar couplings are scaled down, which leads to simplification of the 1H NMR spectra. For some pairs of protons, which are simultaneously J‐ and D‐coupled, the exact values of D can be determined from temperature dependence of Δ. Copyright © 2002 John Wiley & Sons, Ltd.