bluuebunny/crossref_metadata_2025 huggingface dataset:
Survival benefits of adjuvant chemotherapy with oral doxifluridine (5′‐DFUR) following radiotherapy in patients with unresectable pancreatic cancer
Authors: Tsuruta Koji , Okamoto Astutake , Egawa Naoto , Kamisawa Terumi , Karasawa Katsuyuki , Takahashi Toshio
Published: August 2002

Background and Objectives

The combination of 5‐fluorouracil and radiotherapy is thought to be the most effective treatment for locally unresectable pancreatic carcinoma. The outcomes, however, are far from acceptable from the viewpoint of long‐term survival. We assessed the survival benefits of oral adjuvant chemotherapy with doxifluridine (5′‐DFUR) following radiotherapy for patients with the disease.

Methods

Thirty‐five consecutive patients who underwent bypass surgery and radiotherapy for localized advanced unresectable adenocarcinoma of the pancreas head were retrospectively reviewed in regard to disease progression and survival. Ten of the 35 patients underwent adjuvant chemotherapy with 5′‐DFUR after radiotherapy in an outpatient setting.

Results

The 1‐year survival for patients treated with radiotherapy alone was 29%. The 1‐, 2‐, and 3‐year survivals for patients treated with the adjuvant chemotherapy after radiotherapy were 50, 40, and 30%, respectively (P = 0.0069, log‐rank test). The elevation of tumor markers was delayed (P = 0.0346) and local control rate was improved (P = 0.0475) in patients with chemotherapy. Multivariate analysis demonstrated that the adjuvant chemotherapy with 5′‐DFUR was a significant independent prognostic factor as well as tumor size.

Conclusions

The adjuvant chemotherapy with 5′‐DFUR following radiotherapy led to a significant prolongation of the survival for patients with unresectable localized pancreatic cancer. J. Surg. Oncol. 2001;78:202–207. © 2001 Wiley‐Liss, Inc.
Tourism, livelihoods and protected areas: opportunities for fair‐trade tourism in and around National parks
Authors: Goodwin Harold , Roe Dilys
Published: August 2002

The development and implementation of ‘alternative livelihood projects’ by donor agencies and conservation organisations has become one of the most commonly‐applied management prescriptions to alleviate existing or potential conflicts between protected areas and local livelihoods. The use of these projects is a common feature of so‐called Integrated Conservation and Development Projects (ICDPs). In most
cases, the promotion of these initiatives are undertaken as extensions of protected area programmes and often take place in buffer zones. Examples of projects that seek to improve local livelihoods in and around protected areas are common, and many of them have a tourism component. However, the results of tourism components of ICDPs have often been disappointing with local people benefiting little from tourism revenues.

Nevertheless, many national parks are major tourist attractions in rural, and often marginal, areas and do offer significant opportunities for indigenous enterprise development. People living in and around these protected areas often have high expectations of what tourism could offer them. Using data collected in the south east lowveld of Zimbabwe for the DFID Tourism, Conservation and Sustainable Development project an analysis of local people's expectations of tourism is presented. The survey covered nine villages and there are significant differences in the responses. Local people were asked about their experience of tourism and their aspirations, including their preferred ways of earning money from tourism. Finally an analysis of their perceptions of the barriers to their involvement in the industry is presented.

The paper then addresses the ways in which a national park or conservancy might respond to these aspirations and seek to involve local people in tourism enabling them to secure all or part of their livelihood from tourism related employment or entrepreneurial activity. An analysis of the preferences of tourists surveyed in Gonarezhou about activities, which they would wish to participate in if they were available, is presented.

The paper concludes with an analysis of the opportunities for the managers of state, communal or privately owned land to create and support opportunities for local people to participate in the tourism industry and to benefit from fairly traded tourism. These strategies include marketing and business development support, regulation and price management.
Curing kinetics and mechanism of bisphenol S epoxy resin with 4,4′‐Diaminodiphenyl ether or phathlic anhydride
Authors: Shen Shigang , Li Yanfang , Gao Jungang , Sun Hanwen
Published: August 2002

The kinetics of the cure reaction for systems of bisphenol‐S epoxy resin with 4,4′‐diaminodiphenyl ether or phthalic anhydride as a curing agent were investigated with a differential scanning calorimetry. Autocatalytic behavior was shown in the first stages of the cure for the systems, which could be well described by the model proposed by Kamal [Polym Eng Sci 1973, 13, 59–64] that includes two rate constants k1 and k2 and two reaction orders, m and n. k1 and k2 values are observed to increase with the increasing temperature. With the proceeding of the cure reaction, the cross‐linking structure appears, and the reaction is mainly controlled by diffusion in the latter stages. The molecular mechanism of the curing system was discussed. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 558–563, 2001
A new dominant logic and its implications for knowledge management: a study of the Finnish food industry
Authors: Brännback Malin , Wiklund Patricia
Published: August 2002

In this paper changes that have occurred in the Finnish food industry are studied in terms of changes in the dominant logic of the industry. These changes in the dominant logic impact knowledge management processes. The drivers of the changes in the food industry are both technological and market‐based. Biotechnology is turning a traditionally low‐technology industry into a high‐technology industry through the introduction of ‘functional foods’. Knowledge relevant in the traditional food industry is becoming dated and future business success will be dependent on a firm's ability to create and capitalize on new knowledge. Copyright © 2001 John Wiley & Sons, Ltd.
Laser assisted skin closure (LASC) by using a 815‐nm diode‐laser system accelerates and improves wound healing
Authors: Capon A. , Souil E. , Gauthier B. , Sumian C. , Bachelet M. , Buys B. , Polla B.S. , Mordon Serge
Published: August 2002

Background and Objective

This study aimed to evaluate a 815‐nm diode‐laser system to assist wound closure to accelerate and improve healing process.

Study Design/Materials and Methods

A total of 25 male hairless rats (mutant OFA Sprague‐Dawley rats, IFFA‐CREDO, L'Arbresle, France) with four dorsal skin incisions were used for the study. For each wound, the good apposition of the edges was obtained with buried absorbable suture. In the laser group, the laser beam was applied spot by spot through a transparent adhesive dressing along two incisions with the following parameters: 1.5 W; 3 seconds; spot diameter, 2 mm; fluence, 145 J/cm2. Both control wounds were closed with conventional suture techniques. The duration of the closure procedure was noted for each group. Clinical examination, histologic study, and measurement of tensile strength were performed at 3, 7, 15, and 21 days after surgery. Determination of activation of heat shock protein 70 (Hsp70) through immunocytochemistry was performed at days 1 and 7.

Results

LASC was 4 times faster to process than conventional suture: 1 minute 49 ± 20.6 seconds vs. 7 minutes 26 ± 62.2 seconds. In the laser group, healing was accelerated resulting in a more indiscernible scar than in the control groups. Histologic aspect was better with earlier continuous epidermis and dermis and a thinner resulting scar. Tensile strength was 30 to 58% greater than in control groups at 7 and 15 days (P < 0.001). Expression of Hsp70 was markedly induced in skin structures examined after laser exposure.

Conclusions

This study shows the ability of the 815‐nm diode‐laser system to assist wound closure leading to an acceleration and an improvement of wound healing with indiscernible resulting scar. The mechanisms of this phenomenon are still unclear but further investigations are in progress to attempt to explain them. Lasers Surg. Med. 28:168–175, 2001. © 2001 Wiley‐Liss, Inc.
Illusions of marketing planners
Authors: Weber John A.
Published: August 2002

The article highlights the risks of using self‐evaluation as a substitute for primary and secondary market research when designing and monitoring marketing programs. Included is a study of 110 management teams that suggests internally dominated marketing analysis may breed illusory evaluations of a company's own marketing programs versus competitors. If acted upon, such illusions could lead to oversights in developing marketing offerings. The overriding potential implication of the study addresses the allocation of a company's substantial marketing assets—most notably, the risks of bypassing secondary market data and primary market research when developing and evaluating marketing programs. © 2001 John Wiley & Sons, Inc.
Effects of consumer goals on attribute weighting, overall satisfaction, and product usage
Authors: Garbarino Ellen , Johnson Mark S.
Published: August 2002

With the use of field data from a live theater company, this article demonstrates that customers' goal orientation affects not only what information is used in assessing overall satisfaction, but also downstream measures of level of satisfaction and product usage. The study segmented the customers into four groups based on their goal orientations for the established arts goals of cultural enrichment and relaxation, finding that the different groups weigh the attributes of the service differentially in determining overall satisfaction based on each attribute's ability to fulfill their goals. Furthermore, customers whose goals match the organization's orientation give the product a higher evaluation and utilize it more often. © 2001 John Wiley & Sons, Inc.
Induction of a bystander effect in HeLa cells by using a bigenic vector carrying viral thymidine kinase and connexin32 genes
Authors: Tanaka Toshiaki , Yamasaki Hiroshi , Mesnil Marc
Published: August 2002

We previously showed that gap junction intercellular communication mediates the bystander effect in anticancer gene therapy with the herpes simplex virus thymidine kinase (HSV‐tk) and ganciclovir. Because most cancer cell lines have lost their ability to communicate through gap junctions, we investigated whether we could induce such a communication by transferring a gene for a gap junction. We transfected a vector carrying the HSV‐tk (tk) and gap junction (connexin (Cx) 32) genes (Cx32+tk+) into noncommunicating HeLa cells. We compared the cytotoxicity of ganciclovir with mixtures of these cells and HeLa cells that expressed (Cx32+) or did not express (Cx32−) the Cx32 gene. The bystander effect was strong when the two mixed cell types expressed Cx32 (i.e., Cx32+tk+ cells and Cx32+tk− cells). Only 25% of cells survived in this communicating mixture, even when only 10% of the cells were Cx32+tk+. There was also a moderate bystander effect when the Cx32+tk+ cells were mixed with noncommunicating HeLa cells in a 50% ratio. These results demonstrated that the bystander effect is enhanced by Cx32 and suggested that expression of Cx in only one cell type in a mixture can cause a bystander effect. Mol. Carcinog. 30:176–180, 2001. © 2001 Wiley‐Liss, Inc.
Packed capillary column solvating gas chromatography using neat water mobile phase and flame ionization detection
Authors: Wu Naijun , Tang Qinglin , Lippert J. Andreas , Lee Milton L.
Published: August 2002

Neat water at temperatures above its normal boiling point was used as a mobile phase for packed capillary column chromatography. The “universal” flame ionization detector (FID) was used for detection. No restrictor or back pressure was imposed at the column outlet. The effects of temperature on column efficiency and retention were investigated using particle‐bonded continuous bed columns packed and crosslinked with 3 μm polybutadiene‐encapsulated zirconia particles. It was found that when the column inlet pressure was held constant and the temperature was increased to values that were higher than 100°C, the pressure drop decreased rapidly, allowing the use of long columns or small particles. Solute retention factors decreased with increasing temperature; however, column inlet pressure had little effect on retention factor. Mass transfer resistance also decreased with an increase in temperature. Mixtures of alcohols and phenols could be separated within several minutes after the interface between the column and the FID was optimized. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 41–47, 2001
The option to change the use of a property when future property values and construction costs are uncertain
Authors: Gunnelin Åke
Published: August 2002

This paper models the decision to change the use of a property when its value in the current use and the new use, as well as construction costs, are uncertain. In the case of development of vacant land, when cash flows and construction costs are lognormally distributed, the development of the property optimally takes place when the ratio of benefit to cost of development reaches some fixed level. In the redevelopment case, the timing problem is found to be more complex, as the cost of exercising the conversion option consists of two parts, the construction costs and the surrendered value of the property in the current use, which may evolve differently over time. In this case, optimal redevelopment will take place for different benefit–cost ratios, depending on the relative sizes of the property values in the different uses and the construction costs. Also, for a given current benefit–cost ratio, the option value will vary significantly, depending on the relative size of the state variables. Copyright © 2001 John Wiley & Sons, Ltd.
Real estate and corporate valuation: an asset pricing perspective
Authors: Hiang Liow Kim
Published: August 2002

Property is a significant asset in the balance sheets of some Singapore industrial/commerce firms and hotel corporations. In this research, we take on the task of examining the relationship between real estate and stock market valuation of these business firms from an asset pricing perspective. Specifically, the real estate sensitivity of ‘property‐intensive’, non‐real estate stocks is investigated in both a three‐index (market, sector and property) of stock returns and in an arbitrage pricing theory (APT) framework. The APT model is further recast as a multivariate non‐linear regression model with across‐equation restrictions. Using weekly returns on ‘property‐intensive’ stocks in the period 1989–1998 and three shorter‐sample periods, iterated non‐linear seemingly regression techniques (ITNSUR) are employed to obtain joint estimates of stock sensitivities and their associated APT risk ‘prices’. The ‘real estate’ sensitivity is found to be systematic and priced in the APT sense of corporations being paid an ex ante premium for bearing property market risk in investing and owning properties in two of the three sample periods (1989–1991, 1992–1994). The empirical results provide some support that property is a factor in corporate valuation, and is broadly consistent with the efficient markets hypothesis. The implications for portfolio and corporate management are examined. Copyright © 2001 John Wiley & Sons, Ltd.
Prevalence of Parkinson's disease in Cantalejo, Spain: A door‐to‐door survey
Authors: Clavería Luis Erik , Duarte Jacinto , Sevillano Maria Dolores , Pérez‐Sempere Angel , Cabezas Carmen , Rodríguez Fernanda , de Pedro‐Cuesta Jesús
Published: August 2002

We assessed the prevalence of Parkinson's disease in Cantalejo, Spain. In 1994, we screened 1,579 persons (age ≥ 40 years) using a high‐sensitivity method. Cases fulfilling established clinical criteria were followed for a minimum of 3 years. Prevalences were compared with those from other door‐to‐door surveys. We detected 27 individuals with parkinsonism, 20 of whom had Parkinson's disease. The prevalence of Parkinson's disease increased with age and, when age‐adjusted to European standards, was 9.01 per 1,000 (age 40 years and over; 10.78 in men and 5.23 in women). Of the 11 men, three were in Hoehn & Yahr grades III–IV, but six of the nine women were more severely affected. Overall, we found 18 newly diagnosed cases of parkinsonism, 13 of which were Parkinson's disease, and the majority of which were in men aged 80 years or older with a mean duration of illness of 5 years. Our prevalence figures are the highest reported, apparently because of the inclusion of several very elderly men. Parkinson's disease in Cantalejo is less severe in men than in women, particularly in those newly diagnosed. Despite the low numbers, the high prevalence and sex‐related pattern are unexplained but they probably relate to the high sensitivity of the screening method. © 2002 Movement Disorder Society
Genetic polymorphisms of superoxide dismutase in Parkinson's disease
Authors: Farin Federico M. , Hitosis Yolanda , Hallagan Sarah E. , Kushleika John , Woods James S. , Janssen Patricia S. , Smith‐Weller Terri , Franklin Gary M. , Swanson Phillip D. , Checkoway Harvey
Published: August 2002

Oxidative stress reactions may contribute to the pathogenesis of Parkinson's disease (PD). The superoxide dismutases potentially play significant roles in PD by detoxifying superoxide radical. We developed genomic DNA and cDNA‐based sequencing assays to identify genetic variants in the copper/zinc superoxide dismutase (SOD1) and manganese superoxide dismutase (SOD2) genes. No genetic variants were detected in the gene encoding SOD1 in DNA from 45 idiopathic PD cases and 49 controls from a population‐based case‐control study. However, we identified a previously described polymorphism of the mitochondrial targeting sequence consisting of a C47T in exon 2 of SOD2, which results in an alanine to valine substitution. We analyzed this SOD2 variant in DNA from 155 cases and 231 controls from the same study, using an allele‐specific fluorogenic 5′ nuclease assay, and found no differences in the distributions of allelic frequencies. These results indicate that SOD gene variants do not contribute to PD pathogenesis. © 2001 Movement Disorder Society.
Mirthful laughter induced by subthalamic nucleus stimulation
Authors: Krack Paul , Kumar Rajeev , Ardouin Claire , Dowsey Patricia Limousin , McVicker John M. , Benabid Alim‐Louis , Pollak Pierre
Published: August 2002

High‐frequency stimulation of the subthalamic nucleus (STN) improves the motor signs of Parkinson's disease (PD). The three main components (motor, associative, and limbic) of the cortical‐basal ganglia‐cortical circuits pass through the STN. It is not known whether STN stimulation can influence the limbic loop. We present two PD patients in whom acute stimulation of an electrode located in the STN using high stimulation parameters (50% higher than therapeutic) induced funny associations, leading to infectious laughter and hilarity, whereas the therapeutic parameters induced a hypomanic behavior and marked improvement of akinesia. Our report suggests that the STN, with its sensorimotor, cognitive, and limbic parts is not only involved in motor, but also in psychomotor regulation. © 2001 Movement Disorder Society.
Motor imagery in Parkinson's disease: A PET study
Authors: Cunnington R. , Egan G.F. , O'Sullivan J.D. , Hughes A.J. , Bradshaw J.L. , Colebatch J.G.
Published: August 2002

We used positron emission tomography (PET) with 15O‐labelled water to record patterns of cerebral activation in six patients with Parkinson's disease (PD), studied when clinically “off” and after turning “on” as a result of dopaminergic stimulation. They were asked to imagine a finger opposition movement performed with their right hand, externally paced at a rate of 1 Hz. Trials alternating between motor imagery and rest were measured. A pilot study of three age‐matched controls was also performed. We chose the task as a robust method of activating the supplementary motor area (SMA), defects of which have been reported in PD. The PD patients showed normal degrees of activation of the SMA (proper) when both “off” and “on.” Significant activation with imagining movement also occurred in the ipsilateral inferior parietal cortex (both “off” and when “on”) and ipsilateral premotor cortex (when “off” only). The patients showed significantly greater activation of the rostral anterior cingulate and significantly less activation of the left lingual gyrus and precuneus when performing the task “on” compared with their performance when “off.” PD patients when imagining movement and “off” showed less activation of several sites including the right dorsolateral prefrontal cortex (DLPFC) when compared to the controls performing the same task. No significant differences from controls were present when the patients imagined when “on.” Our results are consistent with other studies showing deficits of pre‐SMA function in PD with preserved function of the SMA proper. In addition to the areas of reduced activation (anterior cingulate, DLPFC), there were also sites of activation (ipsilateral premotor and inferior parietal cortex) previously reported as locations of compensatory overactivity for PD patients performing similar tasks. Both failure of activation and compensatory changes are likely to contribute to the motor deficit in PD. © 2001 Movement Disorder Society.
Chemical control of phospholipid distribution across bilayer membranes
Authors: Boon J. Middleton , Smith Bradley D.
Published: August 2002

Most biological membranes possess an asymmetric transbilayer distribution of phospholipids. Endogenous enzymes expend energy to maintain the arrangement by promoting the rate of phospholipid translocation, or flip‐flop. Researchers have discovered ways to modify this distribution through the use of chemicals. This review presents a critical analysis of the phospholipid asymmetry data in the literature followed by a brief overview of the maintenance and physiological consequences of phospholipid asymmetry, and finishes with a list of chemical ways to alter phospholipid distribution by enhancement of flip‐flop. © 2002 Wiley Periodicals, Inc. Med Res Rev, 22, No. 3, 251–281, 2002; Published online in wiley InterScience (www.interscience.wiley.com). DOI 10.1002/med.10009
On the numerical computation of blowing‐up solutions for semilinear parabolic equations
Authors: Fayyad D. , Nassif N.
Published: August 2002

Theoretical aspects related to the approximation of the semilinear parabolic equation: $u_t=\Delta u+f(u)$\nopagenumbers\end, with a finite unknown ‘blow‐up’ time Tb have been studied in a previous work. Specifically, for ε a small positive number, we have considered coupled systems of semilinear parabolic equations, with positive solutions and ‘mass control’ property, such that:
\def\ve{^\varepsilon}$$u_t\ve=\Delta u\ve+f(u\ve)v\ve\qquad v_t\ve=\Delta v\ve‐\varepsilon f(u\ve)v\ve$$\nopagenumbers\end

The solution \def\ve{^\varepsilon}$$\{u\ve,v\ve\}$$\nopagenumbers\end of such systems is known to be global. It is shown that $$\|(u^\varepsilon‐u)(\, .\, ,t)\|_\infty\leq C(M_T)\varepsilon$$\nopagenumbers\end, \def\lt{\char'74}$t\leq T \lt T_b$\nopagenumbers\end
where $M_T=\|u(\, .\, ,T)\|_\infty$\nopagenumbers\end and $C(M_T)$\nopagenumbers\end is given by (6). In this paper, we suggest a numerical procedure for approaching the value of the blow‐up time Tb and the blow‐up solution u. For this purpose, we construct a sequence $\{M_\eta\}$\nopagenumbers\end, with $\lim_{\eta\rightarrow 0}M_\eta=\infty$\nopagenumbers\end. Correspondingly, for $\varepsilon\leq1/2C(M_\eta+1)=\eta^\alpha$\nopagenumbers\end and \def\lt{\char'74}$0\lt\alpha\lt\,\!1$\nopagenumbers\end, we associate a specific sequence of times $\{T_\varepsilon\}$\nopagenumbers\end, defined by $\|u^\varepsilon(\, .\, ,T_\varepsilon)\|_\infty=M_\eta$\nopagenumbers\end. In particular, when $\varepsilon=\eta\leq\eta^\alpha$\nopagenumbers\end, the resulting sequence $\{T_\varepsilon\equiv T_\eta\}$\nopagenumbers\end, verifies, $\|(u‐u^\eta)(\, .\, ,t)\|_\infty\leq{1\over2}(\eta)^{1‐\alpha}$\nopagenumbers\end, \def\lt{\char'74}$0\leq t\leq T_\eta\lt T_{\rm b}$\nopagenumbers\end with $\lim_{\eta\rightarrow 0}T_\eta=T_{\rm b}$\nopagenumbers\end. The two special cases of a single‐point blow‐up where $f(u)=\lambda{\rm e}^u$\nopagenumbers\end and $f(u)=u^p$\nopagenumbers\end are then studied, yielding respectively sequences $\{M_\eta\}$\nopagenumbers\end of order $O(\ln|\ln(\eta)|)$\nopagenumbers\end and $O(\{|\ln(\eta)|\}^{1/p‐1})$\nopagenumbers\end. The estimate $|T_\eta‐T_{\rm b}|/T_{\rm b}=O(1/|\ln(\eta)|)$\nopagenumbers\end is proven to be valid in both cases. We conduct numerical simulations that confirm our theoretical results. Copyright © 2001 John Wiley & Sons, Ltd.
On the approximate solution of some two‐dimensional singular integral equations
Authors: Didenko V. D. , Silbermann B.
Published: August 2002

An approximation method for a wide class of two‐dimensional integral equations is proposed. The method is based on using a special function system. Orthonormality and good interaction with fundamental integral operators arising in partial differential equations are remarkable properties of this system. In addition, all the basis elements can easily be calculated by recurrence relations. Taking into account these properties we construct a numerical algorithm which does not require additional effort (such as quadrature) to compute the values of the fundamental operators on the basis elements. Copyright © 2001 John Wiley & Sons, Ltd.
Kinks and rotations in long Josephson junctions
Authors: Hauck Wolfgang
Published: August 2002

Kinks and rotations are studied in long Josephson junctions for small and large surface losses. Geometric singular perturbation theory is used to prove existence for small surface losses, while numerical continuation is necessary to handle large surface losses. A survey of the system behaviour in terms of dissipation parameters and bias current is given. Linear orbital stability for kinks is proved for small surface losses by calculating the spectrum of the linearized problem. The spectrum is split into essential spectrum and discrete spectrum. For the determination of the discrete spectrum, robustness of exponential dichotomies is used. Puiseux series together with perturbation theory for linear operators are an essential tool. In a final step, a smooth Evans function together with geometric singular perturbation theory is used to count eigenvalues. For kinks, non‐linear orbital stability is shown. For this purpose, the asymptotic behaviour of a semigroup is given and the theory of centre and stable manifolds is applied. Copyright © 2001 John Wiley & Sons, Ltd.
Modeling and measuring the reflection and transmission of a silicon wafer in the X‐ and Ka‐bands under illumination of light in a closed waveguide structure
Authors: Hajian M. , Heijnen S. H. , Groen F. , Hakkert P. , Ligthart L. P.
Published: August 2002

In the past two years, extensive research has been carried out at IRCTR (International Research Centre for Telecommunication‐Transmission and Radar) in order to analyze and model the reflection and transmission coefficients of a semiconductor, i.e., doped silicon, under illumination of light. It was found that the characteristics of the semiconductor material could substantially be changed once it is illuminated with light. This property of the semiconductor material can be used to realize a nonmechanical beam deflector that can form and scan a beam of millimeter‐wave (MMW) radiation at a rapid rate. The preliminary measurements in a closed waveguide structure show that there is a total reflection of MMW and microwave (MW) power after the laser is turned on. The laser light causes a considerable change in the equivalent conductivity of the silicon wafer, changing it from an insulator to a good conductor. The reflection and transmission are modeled using the S–T matrix of the total microwave network. There is a good similarity in the behavior of the theoretical and measurement results. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 349–353, 2001.
Investigation of the wideband operation capability of Gilbert cell mixers
Authors: Cabuk A. , Yeo K. S. , Ma J. G. , Do M. A.
Published: August 2002

The design of a low‐voltage low‐power wideband mixer for radio‐frequency applications is presented in this Letter. Two different input‐matching topologies are employed to see the effects of the matching on the mixer's wideband performance. The new strategy of midway matching is proven to be satisfactory for the wideband applications. Simulations are based on a 0.25‐μm CMOS process. A simulated SSB noise figure of 10.3 dB, a conversion gain of 9.4 dB, and a power consumption of 8.3 mW are among the main achievements. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 97–100, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10237
Reversed circular dichroism of isotropic chiral mediums with negative real permeability and permittivity
Authors: Lakhtakia Akhlesh
Published: August 2002

Negative real parts of the permittivity and permeability lead an isotropic chiral medium to exhibit circular dichroism that is reversed with respect to that exhibited by an identical medium, the real parts of which have positive permittivity and permeability. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 96–97, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10239
Noise modeling of an optically controlled MESFET (OPFET)
Authors: Chakrabarti P. , Jha Vinayak , Kalra Pankaj , Gupta Gaurav
Published: August 2002

The noise performance of an optically controlled MESFET (OPFET) has been reported for the first time. An equivalent noise model of the OPFET has been developed for computation of the noise‐equivalent power (NEP) and signal‐to‐noise ratio at the output of the OPFET. The variations of NEP and SNR with the operating frequency and optical power density have also been carried out. The IC compatibility of the device will make it especially attractive for use in MMICs and OEICs. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 79–83, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10242
Carrier‐concentration‐dependent low‐field‐mobility model for InAlAs/InGaAs/InP lattice‐matched HEMT for microwave application
Authors: Jogi Jyotika , Sen Sujata , Gupta Mridula , Gupta R. S.
Published: August 2002

A carrier‐concentration‐dependent low‐field‐mobility model for a lattice‐matched InAlAs/InGaAs/InP HEMT for microwave frequency applications is developed. The dependence of mobility on carrier concentration affects the current–voltage characteristics, and also the gate–voltage dependence of transconductance. An approximation for the two‐dimensional electron gas (2‐DEG) concentration versus the gate‐to‐channel voltage, which models both the subthreshold region and the gradual saturation of carriers, due to the onset of charge modulation, has been used. The model also evaluates the cutoff frequency as a function of gate length, and a value of 203 GHz is obtained. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 66–70, 2001.
Electro‐optical simulation of a–Si thin‐film‐transistor liquid‐crystal display pixels
Authors: Pena J. M. S. , Pérez I. , Vázquez C. , Otón J. M.
Published: August 2002

An analysis of an amorphous silicon (a–Si) thin‐film‐transistor liquid‐crystal display (TFT–LCD) pixel is presented. The electro‐optical model combines the electrical properties of the switching element and the optical performance of a twisted nematic (TN) liquid‐crystal cell. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 198–199, 2001.
Constitutive tensors of omega‐ and chiroferrites
Authors: Dmitriev V.
Published: August 2002

Using a group‐theoretical approach, constitutive tensors for a new material composed of omega particles embedded in a ferrite are calculated and discussed. The analysis of the tensors is based on the decomposition of them into simplier forms. A comparison of these tensors with the known ones for chiroferrites is made. The constitutive tensors for some modifications of the chiro‐ and omegaferrites are calculated as well. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 201–205, 2001.
Small‐signal modeling of a PHEMT up to 110 GHz based on the genetic algorithm
Authors: Leong Chee Cheong Joseph , Shen Zhongxiang , Tay Lai Choon
Published: August 2002

An improved small‐signal model for a PHEMT (pseudomorphic high‐electron‐mobility transistor) is presented in this paper. Both the extrinsic and intrinsic parameters of the small‐signal model are determined using GA (genetic algorithm) optimization. First, parameter extraction of a small‐signal model is performed on a 2×100 μm PHEMT from 444.6 MHz to 40 GHz. Next, the GA is used to extract the parameters of an improved small‐signal model from 2 up to 110 GHz. The results show very good agreement between calculated and measured S‐parameters over the entire bandwidth. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 367–373, 2001.
Quadrifilar helix antenna with parasitic helical strips
Authors: Chow Yan Wai , Yung Edward Kai Ning , Hui Hon Tat
Published: August 2002

An omnidirectional quadrifilar helix antenna (QHA) with parasitic helical strips for circular polarization (CP) is proposed and experimentally investigated for handheld mobile terminals. This antenna is small in size, low cost, and lightweight. The mutual coupling effect between the grounded helical strips and the feeding helical arms provides a good impedance match, a smaller axial ratio, and wider hemispherical coverage. The impedance bandwidth corresponding to SWR<2 and bandwidth with respect to the axial ratio <3 dB are found to be 39% and 160 MHz at 3.64 GHz, respectively. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 128–130, 2001.
Novel reflected interferometer
Authors: Habli Mohamad A.
Published: August 2002

A novel reflected interferometer is proposed. Two types of the new interferometer are presented. The first type uses a point source, while the second type uses a collimated beam. The new interferometer can be used in surface‐structure testing and sensing. A third type is also presented that can be used as a wave‐meter interferometer. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 136–138, 2001.
Frequency‐dependent behavior of optically illuminated HEMT
Authors: Yajian Huang , Alphones Arokiaswami
Published: August 2002

An analysis of the ac characteristics of an AlGaAs/GaAs HEMT under illumination with modulated light has been carried out for a small‐signal condition. A new model for the photovoltage calculation is outlined. The effect of the signal frequency on the photoconductive current is evaluated; the results show that the photoconductive current is very small, and can be neglected in the calculation. The frequency dependence of the photovoltage along with the 2‐DEG charge density, drain–source current, and transconductance of the device have been studied analytically for an HEMT structure. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 138–142, 2001.
Monte Carlo simulations of particle positions for densely packed multispecies sticky particles
Authors: Ding K. H. , Tsang L. , Shih S. E.
Published: August 2002

The use of the Monte Carlo method to generate particle positions is important in both forward‐ and inverse‐scattering problems of microwave and optical waves in dense media. The generated realizations of a random heterogeneous medium can be used for the numerical solutions of Maxwell's equations. In this paper, we perform Monte Carlo simulations of densely packed sticky particles that have diversity in both size and surface adhesion. The simulation algorithm allows a particle to break or form bonds with other particles during the Monte Carlo displacement. Monte Carlo simulation results are, demonstrated to be in good agreement with Percus–Yevick pair distribution functions. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 187–192, 2001.
Three‐dimensional integrated coil inductor on silicon for high‐frequency applications
Authors: Yeo K. S. , Tan H. P. , Ma J. G. , Do M. A.
Published: August 2002

This letter presents the results of a new 3‐D high‐performance coil inductor, which was fabricated using standard 0.25 μm CMOS technology. Comparative evaluation with the conventional spiral inductor was performed in terms of quality factor (Q), inductance (L), and chip area. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 23–24, 2001.
Bandwidth enhancement in noncentered stacked patches
Authors: Rajo‐Iglesias E. , Segovia‐Vargas D. , Vázquez‐Roy J. L. , González‐Posadas V. , Martín‐Pascual C.
Published: August 2002

A complete study of the bandwidth extension of asymmetrical stacked patches as been carried out. A method that combines the effect of upper patch size and its displacement along the E‐plane axis has been analyzed. Results show new possibilities in the design of such antennas for the two studied cases: square and circular patches. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 53–56, 2001.
A compact Wilkinson power divider with curved PBG cells
Authors: Shum Kam Mam , Xue Quan , Chau Wing Nam , Chan Chi Hou
Published: August 2002

An experimental investigation of a novel compact Wilkinson power divider incorporating a 1‐D PBG slow‐wave structure, in the form of perforation on the curved microstrip line itself, is presented. The size of the power divider is reduced by 22% due to the slow‐wave effect. The inclusion of the PBG cells does not generate additional insertion loss when compared to the conventional design. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 81–83, 2001.
Spectral analysis of cross‐phase modulation in multispan WDM optical fiber systems
Authors: Betti S. , Giaconi M.
Published: August 2002

Wavelength‐division multiplexed optical systems require an accurate knowledge of the cross‐phase modulation due to the Kerr effect, which generates a nonlinear phase modulation of each channel depending on the overall power in all of the other channels. In this letter, the spectral characteristics of cross‐phase modulation are investigated in multispan WDM optical systems, whose performance can be severely constrained by interference induced by this nonlinear effect. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 83–85, 2001.
Method to improve the quality of Moiré signals by ± first‐order Moiré fringes
Authors: Wu Xinmin , Chen Jinbang , Gao Zhishan , Zhu Yingshi , Chen Feiming
Published: August 2002

In an amplitude grating system of small grid pitch, the diffractive effect is distinctive. Its energy will be about 10–40% of the total energy. The diffractive light is the root cause of deterioration of the contrast and sinusoidal property of the Moiré signal. The relations between the phase of ± first‐order Moiré fringes and other factors, such as the gap of the grating pair, are analyzed. It is proposed to use ± first‐order Moiré fringes to obtain high‐quality signals. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 91–93, 2001.
Frequency self‐stabilization of the diffraction radiation oscillator in a biharmonic mode
Authors: Demchenko M. Yu. , Korneenkov V. K. , Kurin V. G.
Published: August 2002

This paper treats the experimentally observed operating features of the diffraction radiation oscillator in a situation of maintaining biharmonic oscillations in the resonant circuit. The process of electron‐beam interaction with biharmonic oscillation is shown to realize intrinsic physical mechanisms of the oscillator frequency stabilization which are put into effect depending on the dispersion competition of the waves in the oscillator resonant cavity. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 112–115, 2001.
Location and imaging of two‐dimensional pipes buried in a lossy half earth
Authors: Kim Jeong‐Seok , Ra Jung‐Woong
Published: August 2002

Several dielectric as well as conducting pipes buried in the lossy half ground are reconstructed from the scattered fields measured along the air–earth interface. The iterative inversion method using the hybrid optimization algorithm combining the genetic and Levenberg–Marquardt algorithms is used in finding the positions, sizes, and medium parameters, such as the permittivities and conductivities, of the buried pipe cylinders, as well as those of the background lossy half ground. Ill posedness of the inversion caused by the errors in the measured scattered fields is regularized by filtering out the evanescent modes of the scattered fields. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 140–143, 2001.
Circulating concentrations of IGF‐I and IGFBP‐3 are not predictive of incidence or clinical behavior of pediatric osteosarcoma
Authors: Rodriguez‐Galindo Carlos , Poquette Catherine A. , Daw Najat C. , Tan Ming , Meyer William H. , Cleveland John L.
Published: August 2002

Background

Preclinical studies suggest a role of insulin‐like growth factor‐1 (IGF‐1) in the proliferation of osteosarcoma cells in vivo. The purpose of this study is to address the relationship between serum levels of IGF‐1 and its binding protein (IGFBP‐3), and the clinical behavior and outcome of osteosarcoma in children, and to compare those levels present in osteosarcoma patients with a normal population.

Procedure

Serum IGF‐1 and IGFBP‐3 levels were determined by ELISA in 37 patients with osteosarcoma treated on the same treatment regimen (OS‐91 protocol), and who had available serum samples from diagnosis. IGF‐1 and IGFBP‐3 levels were compared with those previously established in the normal population, matched for age and gender, and were correlated with the presence of metastatic disease, histologic response to preoperative chemotherapy, and event‐free survival.

Results

In osteosarcoma patients the median IGF‐1 level was 275 ng/ml (range, 105—613) and the median IGFBP‐3 level was 3.4 mg/L (range, 2.3—5.1). IGF‐1 levels differed from those in the normal population (P = 0.029); although we anticipated higher IGF‐1 levels than normal children, 68% of observed standardized scores were less than 0. Furthermore, IGF‐1 or IGFBP‐3 levels failed to correlate with the presence of metastatic disease (P = 0.12 andP =  0.12, respectively), histologic response (Rosen—Huvos grades 3/4 vs. grades 1/2) (P = 0.95 andP = 0.71, respectively), or event‐free survival (P = 0.52 andP = 0.41, respectively). There was a strong association observed between IGF‐1 and IGFBP‐3 levels (P < 0.001).

Conclusions

In this retrospective study of 37 patients, we found that circulating levels of IGF‐1 and IGFBP‐3 are not predictive of the development or clinical characteristics of pediatric osteosarcoma. However, further studies on a larger patient population should be performed in order to investigate this relationship. Med. Pediatr. Oncol. 36:605–611, 2001. © 2001 Wiley‐Liss, Inc.
Cytogenetic abnormalities and clinical outcome in Wilms tumor: A study by the U.K. cancer cytogenetics group and the U.K. Children's Cancer Study Group†
Authors: Bown Nick , Cotterill Simon J. , Roberts Paul , Griffiths Mike , Larkins Simon , Hibbert Steve , Middleton Helen , Kelsey Anna , Tritton Denise , Mitchell Chris
Published: August 2002

Background

Tumor genetic features reported to correlate with adverse outcome in Wilms tumor include karyotype complexity, losses of material from the short arm of chromosome 1 and from the long arms of chromosomes 11, 16 and 22 and gain of material from the long arm of chromosome 1. This study sought to test these associations in a large series of tumors studied by cytogenetic analysis. Identification of markers associated with elevated risk of relapse and fatal outcome could allow more effective treatment stratification at presentation.

Procedure

Thirteen member laboratories of the U.K. Cancer Cytogenetics Group provided results from a 12‐year period. Karyotype abnormalities were correlated with clinical data (age, tumor stage, and histology) and outcome data provided by the central register of the U.K. Children's Cancer Study Group.

Results

Of 127 abnormal karyotypes, 78 included a reputedly “poor prognosis” feature. Univariate survival analysis showed no significant adverse effect for karyotype complexity, 1p loss or 11q loss. The poor outcome of cases with 16q loss was of borderline significance, but this effect was restricted to those tumors with unbalanced translocation der(16)t(1q;16q). The association between relapse risk and gain of 1q material was not significant. Only monosomy 22 was a significant marker of poor outcome in univariate analysis (13 cases showing 50% relapse free survival at 5 years compared to 79% survival for the remaining 114 cases, P = 0.02). In multivariate analysis, significant independent predictors of poor outcome were 1q gain (Hazard Ratio 3.4), stage IV disease (HR 5.0), and monosomy 22 (HR 5.9).

Conclusions

Loss of chromosome 22 identifies high risk Wilms tumors. The prognostic significance of 1q gain, 16q loss and unbalanced translocation der(16)t(1q;16q) is unresolved and warrants further investigation. Med Pediatr Oncol 2002;38:11–21. © 2002 Wiley‐Liss, Inc.
Electronic effects on 13C NMR chemical shifts of substituted 1,3,4‐thiadiazolium salts
Authors: Souza dos Santos Ana Cristina , Echevarria Aurea
Published: August 2002

A series of 3‐ and 4‐X‐cinnamoyl‐1,3,4‐thiadiazolium‐2‐phenylamine chlorides were prepared and fully characterized by spectroscopic techniques. The 13C NMR chemical shifts of the α and β side‐chain carbons were compared with those of the corresponding cinnamic acid precursors and more significant transmission electronic effects were observed for mesoionic compounds. The ratio ρR/ρI for the α and β side‐chain carbons in mesoionic derivatives reflects a more important inductive contribution whereas the value of ρR/ρI for the β side‐chain carbons indicates a higher resonance contribution. The chemical shifts of C‐2 and C‐5 of the heterocyclic ring were correlated with substituent constants and showed that the more extensive conjugation of the side‐chain with an exocyclic moiety is favoured by electron‐withdrawing groups. The correlation analysis of chemical shifts with dual parameters indicated a significant contribution of a resonance effect for C‐2 (ρR/ρI = 1.70) when compared with C‐5 (ρR/ρI = 1.03). Copyright © 2001 John Wiley & Sons, Ltd.
Enantiomeric analysis of (3S,4R)‐4‐(4‐fluorophenyl)‐ 3‐hydroxymethyl‐1‐methylpiperidine by 19F NMR spectroscopy
Authors: Navrátilová Hana
Published: August 2002

The chemical‐shift anisochrony Δδ of the fluorine signal for the enantiomerically enriched (3S,4R)‐4‐(4‐fluorophenyl)‐3‐hydroxymethyl‐1‐methylpiperidine (1a) was induced in the presence of S‐Mosher acid (2) and its magnitude varied with the enantiomeric purity of 1a. Very low quantities of an enantiomeric impurity (1b), ranging typically from 0.2 to 1%, were evaluated by comparing peak areas of 1b with those of 13C satellite signals that were deconvoluted using an automatic Lorentzian line fitting. Isotopic shifts and 13C19F coupling constants were extracted from the corresponding fluorine and carbon spectra. Copyright © 2001 John Wiley & Sons, Ltd.