bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogen peroxide promotes transformation of rat liver non‐neoplastic epithelial cells through activation of epidermal growth factor receptor
Authors: Huang Ruo‐Pan , Peng Ao , Golard Andre , Hossain Moharmmad Z. , Huang Ruochun , Liu Ya‐Guang , Boynton Alton L. 
Published: September 2002

AbstractPrevious studies demonstrated that hydrogen peroxide (H2O2) is a tumor promoter in the rat liver epithelial cell line T51B. We investigated the pathway linking H2O2 to tumor promotion. H2O2 can directly induce tyrosine phosphorylation of epidermal growth factor receptor (EGFR). H2O2 and epidermal growth factor exerted similar effects on the induction of early growth response genes, disruption of gap junction communication, triggering of calcium inflow, and promotion of transformation. Furthermore, the effect of H2O2 on tumor promotion was blocked by abrogation of EGFR activation. Our results suggested that tumor promotion by H2O2 is mediated mainly through activation of EGFR in T51B cells. © 2001 Wiley‐Liss, Inc.
A new method for explaining the generation of aerodynamic forces in flapping flight
Authors: Sunada S. , Ellington C. P. 
Published: September 2002

AbstractSir James Lighthill proposed a method for estimating the hydrodynamic forces generated by slender fish, and his analysis made clear the mechanism of fish swimming. His method is based on slender body theory, and the hydrodynamic forces produced by fish are explained by their kinematics and the added mass of the body sections. More recently, numerical techniques for estimating hydrodynamic forces are making progress, but Lighthill's method is still very important and useful because it contributes to our understanding of the physics of fish swimming.We propose a new method for estimating the aerodynamic forces generated by flapping wings: the forces are explained by the added mass of vortex wake sheets. In concept, it is similar to the momentum theory for fixed wings, which was developed by Prandtl. So, when the forward velocity is large, the method agrees with the momentum theory for a fixed wing. For hovering flight, where vortex sheets are generated continuously, this method agrees with the Rankine–Froude momentum theory of propellers. Like Lighthill's method for swimming, this newly developed method provides useful insight into the physics of flapping wings. Copyright © 2001 John Wiley & Sons, Ltd.
Computation of insect hovering
Authors: Jane Wang Z. 
Published: September 2002

AbstractWe review the results of a recent work on a two‐dimensional mechanism for insect hovering. Resolved computation of two‐dimensional insect hovering shows for the first time that a two‐dimensional hovering motion can generate enough lift to support a typical insect weight. The computation reveals a two‐dimensional mechanism of creating a downward dipole jet of counter‐rotating vortices, which are formed from leading and trailing edge vortices. This suggests that three‐dimensionality is not essential for hovering. The vortex dynamics further eluciates the role of the phase relation between the wing translation and rotation in lift generation. It also gives an intuitive picture of why the instantaneous forces can reach a periodic state after only a few strokes, which in principal enables an insect to take off quickly. The model predicts the lower limits in Reynolds number and amplitude above which the averaged forces are sufficient. Copyright © 2001 John Wiley & Sons, Ltd.
Non‐parabolic band hydrodynamical model of silicon semiconductors and simulation of electron devices
Authors: Romano Vittorio 
Published: September 2002

AbstractA consistent hydrodynamical model for electron transport in silicon semiconductors, free of any fitting parameter, has been formulated in Anile and Romano (Continuum Mechanics Thermodynamics 1999; 11:307–325) and Romano (Continuum Mechanics Thermodynamics 1999; 12:31–51) on the basis of the maximum entropy principle, by considering the energy band described by the Kane dispersion relation. Explicit constitutive functions for fluxes and production terms in the macroscopic balance equations of density, crystal momentum, energy and energy flux have been obtained. Scatterings of electrons with non‐polar optical phonons (both for intervalley and intravalley interactions), acoustic phonons and impurities have been taken into account.In this article we show the link with other macroscopic models describing the motion of charge carriers. In particular, under suitable scaling assumptions, an energy transport model is recovered. An analysis of the formal properties is given by showing that the evolution equations form a hyperbolic system in the physically relevant region of the space of the dependent variables. At last, by using the numerical method developed in Liotta et al. (International Series of Numerical Mathematics 1999; 130:651–660) and Liotta et al. (SIAM Journal on Numerical Analysis 1999, to appear) simulations for bulk silicon and n+–n–n+ silicon diode are performed. The obtained results are in good agreement with the Monte Carlo data. Copyright © 2001 John Wiley & Sons, Ltd.
Clifford geometric parameterization of inequivalent vacua
Authors: Fauser Bertfried 
Published: September 2002

AbstractWe propose a geometric method to parameterize inequivalent vacua by dynamical data. Introducing quantum Clifford algebras with arbitrary bilinear forms we distinguish isomorphic algebras—as Clifford algebras—by different filtrations (resp. induced gradings). The idea of a vacuum is introduced as the unique algebraic projection on the base field embedded in the Clifford algebra, which is however equivalent to the term vacuum in axiomatic quantum field theory and the GNS construction in C*‐algebras. This approach is shown to be equivalent to the usual picture which fixes one product but employs a variety of GNS states. The most striking novelty of the geometric approach is the fact that dynamical data fix uniquely the vacuum and that positivity is not required. The usual concept of a statistical quantum state can be generalized to geometric meaningful but non‐statistical, non‐definite, situations. Furthermore, an algebraization of states takes place. An application to physics is provided by an U (2)‐symmetry producing a gap equation which governs a phase transition. The parameterization of all vacua is explicitly calculated from propagator matrix elements. A discussion of the relation to BCS theory and Bogoliubov–Valatin transformations is given. Copyright © 2001 John Wiley & Sons, Ltd.
The power/frequency‐dependent pulse width and jitter of a 1.55 μm Fabry–Perot laser diode transmitter
Authors: Lin Gong‐Ru , Lee Chung‐Fei 
Published: September 2002

AbstractThe effect of detuning the frequency and power of an electrical comb generator on the peak power, pulse width, and timing jitter of a 1.55 μm Fabry–Perot laser diode transmitter operating in the gain‐switching mode is discussed. The optimal frequencies for achieving the lowest timing jitter (510 MHz), the shortest pulse width (535 MHz), and the largest power (460 MHz) that deviated from theoretical predictions are obtained. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 232–234, 2001.
Matrix analysis of wavelength transmission of arrayed waveguide grating multiplexer
Authors: Aihuang Guo , Junmei Fu 
Published: September 2002

AbstractApplying the matrix transformation, the wavelength‐transmission characteristics of the N×N arrayed waveguide grating multiplexer are analyzed. These wavelength‐transmission characteristics include multiplexing, demultiplexing, wavelength routing, and optical path add and drop multiplexing. The analysis plays an important role in using an AWG multiplexer for a wavelength division multiplexing system. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 249–252, 2001.
Adjacent channel suppression (ACS) in direct‐digital six‐port receivers
Authors: Xu Yansheng , Bosisio Renato G. 
Published: September 2002

AbstractSystem simulation results of a digital six‐port receiver operating with an ideal six‐port (120° between Qi points), over two adjacent channels, are compared with a second six‐port receiver operating with a special six‐port circuit possessing 120° separation between Qi points in the receiving channel and 0° separation between Qi points in the adjacent channel. Theoretical analysis and simulation results are given on adjacent channel suppression using 64‐QAM modulation. The implementation of special six‐port ACS requires a six‐port wave structure with constant phase velocity in the receiving channel and reduced phase velocity in the adjacent channel to decrease the angles of the two adjacent Qi points of the six‐port by 120°. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 265–270, 2001.
Improved method for pulse width calibration in indirectly detected experiments
Authors: Esposito G. , Nadalin L. , Verdone G. , Corazza A. , Viglino P. , Fedrigo M. 
Published: September 2002

AbstractA new sequence for calibrating the pulse width in indirectly detected experiments is described. It uses a field gradient pulse to destroy the transverse magnetization from nuclei that are not coupled to the indirectly detected species. With low natural abundance heteronuclei such as 13C or 15N, the latter component is responsible for a very intense resonance, with large dispersive tails, that hinder the observation of the intensities of the satellite peaks, especially at the null point. The proposed sequence improves the accuracy of the calibration owing to the excellent suppression of the unwanted dispersive signals. We named the sequence ROSSANA, i.e. ROtating Satellite Selective Acquisition at Natural Abundance. Copyright © 2001 John Wiley & Sons, Ltd.
NMR studies of the conformational behaviour and tautomerism of bis‐ and tris‐saccharidoguanidines
Authors: Tóth Gábor , Gáti Tamás , Pintér István , Kovács József , Haessner Rainer 
Published: September 2002

AbstractThe reaction of an acetyl‐protected symmetrical sugar carbodiimide with amines yielded the corresponding trisubstituted guanidine derivatives 2–6 with two or three sugar units. Their tautomerism, isomerism and conformational behaviour were elucidated by application of one‐ and two‐dimensional 1H and 13C NMR spectroscopy. The rate of tautomerisation was calculated from ROESY exchange measurements. Copyright © 2001 John Wiley & Sons, Ltd.
Crystal structure of and conformational equilibria in 1,1′‐dihydroxybis(4H‐cyclopenta[def]phenanthrene) and related derivatives
Authors: Hoang Mary , Mladenova Gabriela , Hopkinson Alan C. , Ramnauth Jailal , Lee‐Ruff Edward 
Published: September 2002

AbstractThe aromatic protons and carbons in the NMR spectra of certain clamped 1,1,2,2‐tetraarylethane‐1,2‐diols undergo intermediate exchange at ambient temperature as the result of conformational equilibrium between two enantiomeric gauche forms. The crystal structures for two of these derivatives show the conformational preference for this geometry in the solid state in contrast to other reported unclamped 1,1,2,2‐tetraarylethane‐1,2‐diols. The conformational preference of these vicinal diols parallels that for the 1,1,2,2‐tetraarylethanes. However, in the asymmetrically substituted diphenylmethylfluorene series, the vicinal diol prefers to adopt a gauche conformation in contrast to the hydrocarbon which prefers the anti geometry attributed to hydrogen bonding effects in the former. The results of AM1 calculations for the conformational preferences of this series of diols and ethanes are included and agree with experimental observations. Copyright © 2001 John Wiley & Sons, Ltd.
NMR and quantum‐chemical study of the stereochemistry of spiroepoxides obtained by oxidation of (Z)‐3‐arylidene‐1‐thioflavan‐4‐ones
Authors: Tóth Gábor , Kovács József , Lévai Albert , Kleinpeter Erich , Koch Andreas 
Published: September 2002

AbstractEpoxidation of (Z)‐3‐arylidene‐1‐thioflavan‐4‐ones (1) yielded trans,cis (2) and trans,trans (3) isomers. The structure and signal assignments were elucidated by extensive application of one‐ and two‐dimensional 1H and 13C NMR spectroscopy. The conformational analysis was achieved by the application of 3J(C,H) couplings and ab initio MO calculations. Both the preferred ground‐state conformers (envelope‐A conformations) obtained as global minima of the HF ab initio structures and the 13C chemical shifts calculated by the GIAO method from the global minima structures of the trans,cis and trans,trans isomers are in agreement with the experimentally obtained NMR results. Copyright © 2001 John Wiley & Sons, Ltd.
Unequivocal assignment of the fullerene carbons of diethyl 1,2‐methano[60]fullerene 61,61‐dicarboxylate using 2D INADEQUATE NMR spectroscopy
Authors: Burley Glenn A. , Keller Paul A. , Pyne Stephen G. , Ball Graham E. 
Published: September 2002

AbstractAssignment of all carbons of the [60]fullerene sphere of diethyl 1,2‐methnano[60]fullerene 61,61‐dicarboxylate using 2D INADEQUATE NMR spectroscopy is described. Acquiring the INADEQUATE data with small spectral widths and optional F1 folding with States‐TPPI phase implementation provides a convenient route to high‐resolution data. A description of the topology of the [60]fullerene sphere and its comparison with x‐ray crystallographic analysis is also presented. Copyright © 2001 John Wiley & Sons, Ltd.
Special reactions of α,β‐unsaturated ketones: Part II. Structure and stereochemistry of perhydro‐5a,11a‐epoxydibenz[b,f]oxepin‐4a‐ol, a bridged Diels–Alder dimer of 2‐methylenecyclohexanone
Authors: Gößnitzer Edith , Wendelin Winfried 
Published: September 2002

AbstractThe paper deals with the structure elucidation of (4aRS,5aRS,9aRS,11aRS)‐perhydro‐5a,11a‐epoxydibenz[b,f]oxepin‐4a‐ol (6), which is unexpectedly formed from 2‐dimethylaminomethylcyclohexanone hydrochloride (1·HCl) in the presence of phenylguanidine in boiling ethanol. In detail, two molecules of 2‐methylenecyclohexanone (generated from 1 by elimination of dimethylamine) afforded via Diels–Alder reaction, subsequent addition of water and ring closure a product C14H22O3, which finally proved to be the title compound. The structure of the tetracyclic hemiacetal 6 was deduced from one‐ and two‐dimensional NMR experiments (1D TOCSY, DEPT‐135, 1H,1H‐COSY, gs‐HSQC, gs‐HMBC, gs‐HSQC‐TOCSY). In particular, the one‐dimensional selective TOCSY and the gradient‐selected HSQC‐TOCSY, performed as a pseudo‐3D experiment without the evolution period in the TOCSY part, proved to be very helpful for the unambiguous assignment of signals in overcrowded regions. NOE data confirmed the stereochemistry of epoxydibenzoxepinol 6. Copyright © 2001 John Wiley & Sons, Ltd.
Ovarian expression of melatonin Mel1a receptor mRNA during mouse development
Authors: Lee Chang Joo , Do Byung Rok , Lee Yang Han , Park Jong Hyuk , Kim Sun Jong , Kim Jin Kyu , Roh Sung Il , Yoon Yong‐Dal , Yoon Hyun Soo 
Published: September 2002

AbstractMelatonin, secreted by the pineal gland, is involved in the regulation of many physiological functions of various species of animals. In the present study, the expression of gene for melatonin Mel1a receptor (MelR) was evaluated in the ovary, hypothalamus, and pituitary according to the developmental stages in female mice. Semiquantitative reverse‐transcription polymerase chain reaction (RT‐PCR) and in situ PCR techniques were applied. According to the developmental stages, gene for MelR was differently expressed on ovary, hypothalamus, and pituitary. MelR gene was first expressed on pituitary prior to the expression in hypothalamus and ovary. Ovarian MelR gene started to express at birth. Unlike hypothalamic expression of MelR gene which was identified after birth, in pituitary, it was expressed at 16 days post coitum. In the ovary, the expression signal of MelR gene was identified on granulosa cells. However, the signal was not detected in the theca cells. It was weak in the primordial and atretic follicles. Taken together, it can be considered that melatonin has a pivotal role in the folliculogenesis. Mol. Reprod. Dev. 59:126–132, 2001. © 2001 Wiley‐Liss, Inc.
Development of a PEDRI free‐radical imager using a 0.38 T clinical MRI system
Authors: Lurie David J. , Li Haihong , Petryakov Sergey , Zweier Jay L. 
Published: September 2002

AbstractProton electron double resonance imaging (PEDRI) uses the Overhauser effect to image the distribution of free‐radicals in biological samples and animals. Standard MRI hardware and software is used, with the addition of hardware to irradiate the free‐radical‐of‐interest's EPR resonance. For in vivo applications it must be implemented at a sufficiently low magnetic field to result in an EPR irradiation frequency that will penetrate the sample but will not cause excessive nonresonant power deposition therein. Many clinical MRI systems use resistive magnets that are capable of operating at 10–20 mT, and which could thus be used as PEDRI imagers with the addition of a small amount of extra hardware. This article describes the conversion of a 0.38 T whole‐body MRI system for operation as a 20.1 mT small‐animal PEDRI imager. The magnet power supply control electronics required a small modification to operate at the lower field strength, but no permanent hardware changes to the MRI console were necessary, and no software modification was required. Frequency down‐ and up‐conversion was used on the NMR RF system, together with a new NMR/EPR dual‐resonance RF coil assembly. The system was tested on phantoms containing free‐radical solution, and was also used to image the distribution of a free‐radical contrast agent injected intravenously into anesthetized mice. Magn Reson Med 47:181–186, 2002. © 2002 Wiley‐Liss, Inc.
Multiple field of view MR fluoroscopy
Authors: Aksit Pelin , Derbyshire J. Andrew , Serfaty Jean‐Michel , Atalar Ergin 
Published: September 2002

AbstractThis work describes a real‐time imaging and visualization technique that allows multiple field of view (FOV) imaging. A stream of images from a single receiver channel can be reconstructed at multiple FOVs within each image frame. Alternately, or in addition, when multiple receiver channels are available, image streams from each channel can be independently reconstructed at multiple FOVs. The implementation described here provides for real‐time visualization of the placement of guidewires and catheters on a dynamic roadmap during interventional procedures. The loopless catheter antenna, an electrically active intravascular probe, was used for MR signal reception. In 2D projection images, the catheter and surrounding structures within its diameter of sensitivity appear as bright signal. The simplicity of the resulting images allows very‐narrow‐FOV imaging to decrease imaging time. Very‐narrow‐FOV images are acquired on MR receiver channels that collect guidewire or catheter data. These very‐narrow‐FOV images provide very high frame rate continuous, real‐time imaging of the interventional devices (25 fps). Large‐FOV images are formed from receiver channels that collect anatomical data from standard imaging surface coils, and simultaneously provide a dynamic, frequently updated roadmap. These multiple‐FOV images are displayed together, improving visualization of interventional device placement. Magn Reson Med 47:53–60, 2002. © 2002 Wiley‐Liss, Inc.
High b‐value q‐space analyzed diffusion‐weighted MRI: Application to multiple sclerosis
Authors: Assaf Y. , Ben‐Bashat D. , Chapman J. , Peled S. , Biton I.E. , Kafri M. , Segev Y. , Hendler T. , Korczyn A.D. , Graif M. , Cohen Y. 
Published: September 2002

AbstractMultiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) which affects nearly one million people worldwide, leading to a progressive decline of motor and sensory functions, and permanent disability. High b‐value diffusion‐weighted MR images (b of up to 14000 s/mm2) were acquired from the brains of controls and MS patients. These diffusion MR images, in which signal decay is not monoexponential, were analyzed using the q‐space approach that emphasizes the diffusion characteristics of the slow‐diffusing component. From this analysis, displacement and probability maps were constructed. The computed q‐space analyzed MR images that were compared with conventional T1, T2 (fluid attenuated inversion recovery (FLAIR)), and diffusion tensor imaging (DTI) images were found to be sensitive to the pathophysiological state of white matter. The indices used to construct this q‐space analyzed MR maps, provided a pronounced differentiation between normal tissue and tissues classified as MS plaques by the FLAIR images. More importantly, a pronounced differentiation was also observed between tissues classified by the FLAIR MR images as normal‐appearing white matter (NAWM) in the MS brains, which are known to be abnormal, and the respective control tissues. The potential diagnostic capacity of high b‐value diffusion q‐space analyzed MR images is discussed, and experimental data that explains the consequences of using the q‐space approach once the short pulse gradient approximation is violated are presented. Magn Reson Med 47:115–126, 2002. © 2002 Wiley‐Liss, Inc.
Postacquisition suppression of large‐vessel BOLD signals in high‐resolution fMRI
Authors: Menon Ravi S. 
Published: September 2002

AbstractLarge‐vessel BOLD contamination is a serious impediment to localization of neural activity in high‐resolution fMRI studies. A new method is presented which estimates and removes the fraction of BOLD signal that arises from oriented vessels, such as cerebral and pial veins in a voxel, by measuring their influence on the phase angle of the complex valued fMRI time series. A maximum likelihood estimator based on a linear least‐squares fit of the BOLD signal phase to the BOLD signal magnitude in a voxel is shown to efficiently suppress the BOLD effect from these larger veins, whose activation is not well colocalized with the neural response. In high‐resolution in vivo fMRI data at 4 T, it is estimated that the method is sensitive to the phase changes in the cerebral, larger intracortical, and pial veins. The technique requires no special pulse sequence modifications or acquisition strategies, and is computationally fast and intrinsically robust. Magn Reson Med 47:1–9, 2002. © 2002 Wiley‐Liss, Inc.
Separation of intra‐ and extracellular lactate NMR signals using a lanthanide shift reagent
Authors: Aime Silvio , Botta Mauro , Mainero Valentina , Terreno Enzo 
Published: September 2002

AbstractThis work describes the use of [Pr‐DO3A] as a shift reagent for differentiating intra‐ and extracellular L‐lactate resonance in 1H‐ and 13C‐NMR spectra. DO3A acts as heptadentate ligand towards lanthanide(III) ions, leaving two coordination vacancies for the coordination of the L‐lactate ion. The exchange between free and [Pr‐DO3A]‐bound L‐lactate is fast on the NMR timescale, thus yielding a paramagnetically shifted L‐lactate signal for the substrate in the compartment containing the paramagnetic chelate. The evaluation of the method was carried out on a model system based on sealed ghosts from human red blood cells. Magn Reson Med 47:10–13, 2002. © 2002 Wiley‐Liss, Inc.