bluuebunny/crossref_metadata_2025_split huggingface dataset:
Noise modeling of an optically controlled MESFET (OPFET)
Authors: Chakrabarti P. , Jha Vinayak , Kalra Pankaj , Gupta Gaurav 
Published: August 2002

AbstractThe 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

AbstractA 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

AbstractAn 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

AbstractUsing 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

AbstractAn 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

AbstractAn 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

AbstractA 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

AbstractAn 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

AbstractThe 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

AbstractThis 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

AbstractA 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

AbstractAn 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

AbstractWavelength‐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

AbstractIn 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

AbstractThis 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

AbstractSeveral 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

AbstractBackgroundPreclinical 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.ProcedureSerum 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.ResultsIn 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).ConclusionsIn 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

AbstractBackgroundTumor 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.ProcedureThirteen 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.ResultsOf 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).ConclusionsLoss 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

AbstractA 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

AbstractThe 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.
Quantitative analysis of flagellar movement in hyperactivated and acrosome‐reacted golden hamster spermatozoa
Authors: Ishijima Sumio , Baba Shoji A. , Mohri Hideo , Suarez Susan S. 
Published: August 2002

AbstractCaudal epididymal spermatozoa of golden hamsters were incubated in capacitation medium. Their movement patterns changed as they became hyperactivated and underwent the acrosome reaction. To understand the basic mechanism by which changes in movement pattern are brought about, digital image analysis was carried out on the flagellar movements recorded with a video system. The degree of flagellar bending increased with incubation time, especially in the proximal midpiece. The hyperactivated spermatozoa had remarkably asymmetrical flagellar waves of large amplitude because either the bends in the same direction as the hook of the head (referred as the “pro‐hook bend”) or the bends in the opposite direction to the hook of the head (referred as the “anti‐hook bend”) extremely increased their curvature; whereas, the acrosome‐reacted spermatozoa had relatively symmetrical flagellar waves of large amplitude because both the pro‐ and anti‐hook bends remarkably increased their curvature. Beat frequency significantly decreased while wavelength of flagellar waves increased after hyperactivation and further after the acrosome reaction. These results suggest that both extreme pro‐ and anti‐hook bends are essential in the acrosome‐reacted spermatozoa even though beat frequency decreased markedly.Mol. Reprod. Dev. 61: 376–384, 2002. © 2002 Wiley‐Liss, Inc.
Localization of plasminogen in the extracellular matrix of hamster eggs: Exogenous activation by streptokinase
Authors: Jiménez‐Díaz María , Roldán Mariela , Miceli Dora C. 
Published: August 2002

AbstractThe plasminogen activator (PA)/plasminogen/plasmin proteolytic system has begun to be taken into account in the fertilization process. In this study, we demonstrated the presence of plasminogen in the extracellular matrix (ECM) of hamster oocytes by indirect immunofluorescence and immunoperoxidase assays using human anti‐plasminogen. Plasminogen appeared first on the zona pellucida (ZP) of ovarian oocytes and later on the plasma membrane (PM) of oviducal eggs. This would suggest that oviducal oocytes modulate the expression of plasminogen binding sites on the PM. Human plasminogen as well as that of other species, known to be activated by streptokinase (SK), is rapidly converted to a plasmin‐SK complex. We demonstrated the rapid formation of a SK‐plasminogen complex that yields plasmin in the blood plasma of hamsters. Both the in vivo and in vitro SK treatment of eggs from superovulated female hamsters caused a decreased in the ZP dissolution time (ZPdt), probably either due to the proteolytic effect of plasmin or due to the SK‐Plasminogen. Extracellular proteolysis assays carried out on agar–casein plates confirmed the proteolytic activity of SK‐incubated eggs; the controls, on the contrary, failed to display a halo. These studies show that (1) superovulated hamster eggs contain plasminogen in their ECM, (2) oviducal eggs exhibit plasminogen on their PMs, indicating the presence of their corresponding binding sites, (3) in hamsters, SK, a non‐enzymatic exogenous protein would be capable of activating ECM plasminogen to plasmin, and (4) the complex SK‐plasminogen and/or the plasmin are capable of changing the ZPdt with α‐chymotrypsin. Mol. Reprod. Dev. 61:528–535, 2002. © 2002 Wiley‐Liss, Inc.
Effect of extracellular matrix proteins on in vitro testosterone production by rat Leydig cells
Authors: Diaz Emilce S. , Pellizzari Eliana , Meroni Silvina , Cigorraga Selva , Lustig Livia , Denduchis Berta 
Published: August 2002

AbstractThe aim of this study was to detect the effect of extracellular matrix (ECM) proteins on rat Leydig cell shape, adhesion, expression of integrin subunits and testosterone production, in vitro. Leydig cells isolated from adult rats were cultured on plates uncoated or coated with different concentrations of laminin‐1, fibronectin, or type IV collagen in the presence or absence of hCG for 3 or 24 hr. A significant increase of cell adhesion and of α3, α5, and β1 integrin subunit expression was observed when cells were cultured on ECM proteins, compared to those grown on uncoated plates. Leydig cells cultured on glass coverslips coated with ECM proteins for 24 hr exhibited elongated shapes with long cell processes (spreading), while cells cultured on uncoated plates showed few cell processes. A significant decrease in testosterone production was observed when basal and hCG‐stimulated Leydig cells were cultured for 3 or 24 hr on plates coated with type IV collagen (12 and 24 μg/cm2) compared to uncoated plates. A significant though a slighter decrease in testosterone production was also observed in cells cultured on plates coated with fibronectin (12 and 24 μg/cm2), compared to uncoated plates. Laminin‐1 did not modify testosterone production under basal or hCG stimulated conditions. These results suggest that ECM proteins are able to modulate Leydig cell steroidogenesis, in vitro. Mol. Reprod. Dev. 61:493–503, 2002. © 2002 Wiley‐Liss, Inc.