bluuebunny/crossref_metadata_2025_split huggingface dataset:
A parallel implementation of an evolutionary‐based automatic tool for microwave circuit synthesis: Preliminary results
Authors: Caorsi Salvatore , Donelli Massimo , Massa Andrea , Raffetto Mirco 
Published: October 2002

AbstractIn this paper a CAD tool for the automatic design of passive microwave components is described. It is based on a genetic algorithm optimizer and a three‐dimensional finite element simulator. The main feature of the proposed tool is its ability, achieved by means of the parallel virtual machine software package, to fully exploit any concurrent computational resource. The effectiveness of the proposed approach is preliminarily assessed by considering the synthesis of a rectangular waveguide power divider. Selected numerical results confirm the capabilities, but also the current limitations, of the presented methodology. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 169–172, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10547
Antenna integration with a waveguide photodetector for high capacity wireless communications
Authors: Khodier Majid M. , Christodoulou Christos G. , Liao Tsai S. , Yu Paul K. L. 
Published: October 2002

AbstractThis paper proposes the integration of an antenna with a photodetector for high capacity wireless communications. A waveguide photodetector (WGPD), illuminated on the side, is used to convert the RF‐modulated optical power into a microwave signal. That microwave signal is used to feed an antenna built on the same plane as the photodetector. The WGPD is a standard p‐i‐n device grown on a semi‐insulating InP. The performance of this RF/photonic antenna in the frequency range 17–20 GHz is studied theoretically and experimentally. An equivalent circuit model for the WGPD is developed to predict the photodetector impedance as a function of frequency. The photodetector is matched to the input impedance of the antenna. The agreement between measurement and the circuit model results for the WGPD impedance is very good. It is envisioned that a large number of such RF/Photonic antenna elements could be networked together into a star configuration, feeding in and out of a radio hub. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 179–184, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10550
Power characteristics of dielectric optical Piet Hein waveguides
Authors: Choudhury P. K. 
Published: October 2002

AbstractA fairly rigorous analytical treatment of the power characteristics of dielectric optical waveguides with Piet Hein core‐cross sectional geometry is presented in this paper. This kind of waveguide structure would be advantageous owing to the absence of corners, which are found in rectangular guides, resulting in undesirable loss due to the scattering of light. In order to simplify this theoretical approach, an approximation of vanishing refractive index difference between the guiding and the non‐guiding sections is implemented. The variation of logarithmic power is shown for different dimensions of the core, corresponding to different azimuthal modal indices. It is found that the modes with higher index values carry less logarithmic power in the lower tail of the propagation's constant range, and this feature affects the higher tail. A better kind of uniformity of the power distribution is observed near the higher tail of the range of propagation constants. This feature would lead to useful applications of these guides in integrated optic technology. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 236–240, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10567
A fast iterative physical optics (FIPO) algorithm based on non‐uniform polar grid interpolation
Authors: Boag Amir 
Published: October 2002

AbstractIn this paper, a novel fast iterative physical optics (FIPO) algorithm is proposed for analysis of scattering from electrically large objects involving multiple reflections such as the case for open‐ended cavities. At each iteration, the physical optics current induced on the surface of the scatterer produces a correction to the incident field, which in turn induces a correction to the physical optics current. The FIPO algorithm relies on fast field evaluation, which is achieved via domain decomposition of the scatterer surface and comprises two steps repeated for each subdomain. First, computation of the field is produced by currents residing within a subdomain over a sparse set of points surrounding the scatterer. Second, phase removal, interpolation, phase restoration, and aggregation of the field of the subdomain are integrated into the total field on the surface. The proposed approach can be extended to fast iterative solution of problems discretized via the method of moments. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 240–244, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10568
Thallium(III) coordination compounds: chemical information from 205Tl NMR longitudinal relaxation times
Authors: Bodor Andrea , Bányai István , Kowalewski Jozef , Glaser Julius 
Published: October 2002

Abstract205Tl longitudinal relaxation rate measurements were performed on several thallium(III) complexes with the composition Tl(OH)n(H2O)6−n(3−n)+ (n = 1,2), Tl(Cl)n(H2O)m−n(3−n)+, Tl(Br)n(H2O)m−n(3−n)+ (m = 6 for n = 1–2, m = 5 for n = 3, m = 4 for n = 4), Tl(CN)n(H2O)m−n(3−n)+ (m = 6 for n = 1–2, m = 4 for n = 3–4) in aqueous solution, at different magnetic fields and temperatures. 13C and 2D isotopic labelling and 1H decoupling experiments showed that the contribution of the dipolar relaxation path is negligible. The less symmetric lower complexes (n < 4) had faster relaxation rate dominantly via chemical shift anisotropy contribution which depended on the applied magnetic field: T1 values are between 20 and 100 ms at 9.4 T and the shift anisotropy is Δσ = 1000–2000 ppm. The tetrahedral complexes, n = 4, relax slower; their T1 is longer than 1 s and the spin–rotation mechanism is probably the dominant relaxation path as showed by a temperature dependence study. In the case of the TlCl4− complex, presumably a trace amount of TlCl52− causes a large CSA contribution, 300 ppm. Since the geometry and the bond length for the complexes in solution are known from EXAFS data, it was possible to establish a correlation between the CSA parameter and the symmetry of the complexes. The relaxation behaviour of the Tl–bromo complexes is not in accordance with any known relaxation mechanism. Copyright © 2002 John Wiley & Sons, Ltd.
Evidence that anandamide‐signaling regulates human sperm functions required for fertilization
Authors: Schuel Herbert , Burkman Lani J. , Lippes Jack , Crickard Kent , Mahony Mary C. , Giuffrida Andrea , Picone Robert P. , Makriyannis Alexandros 
Published: October 2002

AbstractEjaculated mammalian sperm require several hours exposure to secretions in female reproductive tracts, or incubation in appropriate culture medium in vitro, before acquiring the capacity to fertilize eggs. Arachidonylethanolamide (AEA), also known as anandamide, is a novel lipid‐signal molecule that is an endogenous agonist (endocannabinoid) for cannabinoid receptors. We now report that AEA is present in human seminal plasma, mid‐cycle oviductal fluid, and follicular fluid analyzed by high‐performance liquid chromatography/mass spectrometry. Sperm are sequentially exposed to these reproductive fluids as they move from the vagina to the site of fertilization in the oviduct. Specific binding of the potent cannabinoid agonist [3H]CP‐55,940 to human sperm was saturable (KD 9.71 ± 1.04 nM), suggesting that they express cannabinoid receptors. R‐methanandamide [AM‐356], a potent and metabolically stable AEA analog, and (−)Δ9 tetrahydrocannabinol (THC), the major psychoactive constituent of Cannabis, modulated capacitation and fertilizing potential of human sperm in vitro. AM‐356 elicited biphasic effects on the incidence of hyperactivated sperm motility (HA) between 1 and 6 hr of incubation: at (2.5 nM) it inhibited HA, while at (0.25 nM) it stimulated HA. Both AM‐356 and THC inhibited morphological alterations over acrosomal caps between 2 and 6 hr (IC50 5.9 ± 0.6 pM and 3.5 ± 1.5 nM, respectively). Sperm fertilizing capacity, measured in the Hemizona Assay, was reduced 50% by (1 nM) AM‐356. These findings suggest that AEA‐signaling may regulate sperm functions required for fertilization in human reproductive tracts, and imply that smoking of marijuana could impact these processes. This study has potential medical and public policy ramifications because of the incidence of marijuana abuse by adults in our society, previously documented reproductive effects of marijuana, and the ongoing debate about medicinal use of marijuana and cannabinoids. Mol. Reprod. Dev. 63: 376–387, 2002. © 2002 Wiley‐Liss, Inc.
Reduction of flow‐related signal loss in flow‐compensated 3D TOF MR angiography, using variable echo time (3D TOF‐VTE)
Authors: Jeong Eun‐Kee , Parker Dennis L. , Tsuruda Jay S. , Won Jong‐Yun 
Published: October 2002

AbstractHigh‐resolution MRA with phase/frequency flow compensation may require very long echo times (TEs). Variable TE (VTE) was implemented into flow‐compensated 3D TOF to minimize the effective TE and reduce the flow‐related signal void. Thek‐space of the 3D TOF was divided into segment groups ranging from two to 32 segments with different TEs. The TEs were minimized and the flow‐compensation gradient lobes were calculated to null the total first moment at the peak of the echo for each segment. Possible artifacts and off‐resonance effects were evaluated, with respect to the number of TE segments, using the point spread function (PSF) and corresponding experiments. The optimal number of TE segments for the least artifact was determined to be one‐half of the number of slices. Two types of artifacts caused by VTE were predicted and subsequently observed. The developed pulse sequence 3D TOF‐VTE was tested on clinical MRI systems, by performing scans of the cervical carotid artery and intracranial carotid artery at the carotid siphon. The signal distribution near the bifurcation and the siphon was much more uniform with VTE, and the flow‐related signal loss was greatly reduced. The resultant MR angiograms provided improved vessel detail. The results show that VTE improved the quality of flow‐compensated 3D TOF MRA. Magn Reson Med 48:667–676, 2002. © 2002 Wiley‐Liss, Inc.
Improved white matter fiber tracking using stochastic labeling
Authors: Tench C.R. , Morgan P.S. , Blumhardt L.D. , Constantinescu C. 
Published: October 2002

AbstractDiffusion tensor imaging (DTI) promises a robust means of visualizing in vivo white matter fibers in individual subjects, and of inferring direct connectivity between distant points in the brain. By following the primary eigenvector of the diffusion tensor, trajectories may be defined that trace the path of the underlying fiber tract. However, fiber tracking is prone to cumulative error from acquisition noise and partial volume, which limits the repeatability of such techniques. An image‐processing method based on stochastic labeling, by which the noisy primary eigenvectors may be reconfigured according to anatomically reasonable assumptions, is described. The method's potential to improve fiber tracking is first demonstrated on numerical test data. It is then applied to real data acquired from healthy volunteers. Trajectories defined within the corpus callosum and the pyramidal tracts are rendered using 3D graphic imaging software, and the results are compared before and after processing. Fiber tracking was shown to produce anatomically plausible results, and typical errors were largely resolved by the method. Further, the sensitivity of trajectories to their start point was greatly reduced after processing. The use of stochastic labeling may therefore improve the reliability of experiments using white matter fiber tracking. Magn Reson Med 48:677–683, 2002. © 2002 Wiley‐Liss, Inc.
Regularized higher‐order in vivo shimming
Authors: Kim Dong‐Hyun , Adalsteinsson Elfar , Glover Gary H. , Spielman Daniel M. 
Published: October 2002

AbstractA regularized algorithm is presented for localized in vivo shimming. The technique uses first‐ (X,Y,Z), second‐ (Z2, ZX, ZY, X2‐Y2, XY), and third‐order (Z3) shim coils, and is robust when applied to arbitrarily‐shaped, as well as off‐center, regions of interest (ROIs). A single‐shot spiral pulse sequence is used for rapid field map acquisition, and a least‐squares calculation of the shim currents is performed to minimize the root‐mean‐square (RMS) value of the B0 inhomogeneity over a user‐selected ROI. The use of a singular value decomposition (SVD) in combination with a regularization algorithm significantly improves the numerical stability of the least‐squares fitting procedure. The fully automated shimming package is implemented on a 3 T GE Signa system and its robust performance is demonstrated in phantom and in vivo studies. Magn Reson Med 48:715–722, 2002. © 2002 Wiley‐Liss, Inc.
Comparison of collagen dynamics in articular cartilage and isolated fibrils by solid‐state NMR spectroscopy
Authors: Huster Daniel , Schiller Jürgen , Arnold Klaus 
Published: October 2002

AbstractNative pig articular cartilage was investigated by 13C cross polarization (CP) magic angle spinning (MAS) NMR at a magnetic field strength of 17.6 T. CP MAS spectra of cartilage are dominated by resonances from rigid collagen, while only low‐intensity signals from the glycosaminoglycans are observed. The spectral resolution of collagen fibrils in native cartilage is somewhat higher than for isolated collagen fibrils from bovine achilles tendon investigated for comparison. This is confirmed qualitatively by 1H‐1H wideline separation spectra that show much lower line widths for cartilage collagen compared to isolated collagen. The strength of 1H‐13C dipolar couplings was measured in a 2D LG CP experiment providing a motionally averaged dipolar coupling value for each resolved signal. These scaled couplings were converted to molecular order parameters for the CH bond vector. Typical order parameters for isolated collagen were 0.91–0.96 for sidechains and 0.98–1.00 for the backbone. Somewhat lower order parameters were determined for cartilage collagen; 0.79–0.90 for the sidechain and 0.92–0.97 for the backbone. The only glycosaminoglycan signals that could be detected by CP MAS show order parameters of 0.48–0.92 and are assigned to relatively rigid hyaluronan and keratan sulfate. The higher mobility of collagen in cartilage is due to the high water content and collisions with the isotropically mobile glycosaminoglycans, such as chondroitin sulfate. Therefore, the mobility of cartilage macromolecules is broadly distributed from almost completely rigid to highly mobile, which lends cartilage its mechanical strength and shock‐absorbing properties. Magn Reson Med 48:624–632, 2002. © 2002 Wiley‐Liss, Inc.
Phenotypic variability among first‐degree relatives with carnitine palmitoyltransferase II deficiency
Authors: Vladutiu Georgirene D. , Bennett Michael J. , Fisher Nadine M. , Smail David , Boriack Richard , Leddy John , Pendergast David R. 
Published: October 2002

AbstractCarnitine palmitoyltransferase (CPT) II deficiency disorders are clinically very variable. To examine the cause(s) of variable symptoms in first‐degree relatives with CPT II deficiency, four sisters with various combinations of mutations and polymorphisms in the CPT2 gene were studied, together with 20 sedentary and 24 trained healthy female subjects. One sister, whose symptoms began at age 7 years, was more severely affected than her older sister, whose symptoms began at age 16 years; both were compound heterozygotes for the common S113L mutation and Q413fs, and for the common CPT2 polymorphisms, V3681 and M647V. A third sister became hypoglycemic with fasting, was heterozygous for the S113L mutation, and homozygous for the polymorphism variants. The fourth sister was asymptomatic, heterozygous for the Q413fs mutation, and homozygous for the normal polymorphisms. Residual CPT II activity in skeletal muscle and cultured skin fibroblasts from the two myopathic sisters, and palmitate oxidation in fibrobasts, were abnormally low; cellular and total body fat oxidation were also diminished. Muscle function and fat oxidation were nomal at rest, but a switch to carbohydrate utilization occurred at lower exercise intensities than in sedentary and trained individuals, respectively. Reliance on carbohydrates during stress and hormonal alterations may explain, in part, the variance in ages of onset and serverity of symptoms in myopathic patients. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 492–498, 2002
Parameter identification for lined tunnels in a viscoplastic medium
Authors: Lecampion B. , Constantinescu A. , Nguyen Minh D. 
Published: October 2002

AbstractThis paper is dedicated to the identification of constitutive parameters of elasto‐viscoplastic constitutive law from measurements performed on deep underground cavities (typically tunnels). This inverse problem is solved by the minimization of a cost functional of least‐squares type. The exact gradient is computed by the direct differentiation method and the descent is done using the Levenberg–Marquardt algorithm. The method is presented for lined or unlined structures and is applied for an elastoviscoplastic constitutive law of the Perzyna class. Several identification problems are presented in one and two dimensions for different tunnel geometries. The used measurements have been obtained by a preliminary numerical simulation and perturbed with a white noise. The identified responses match the measurements. We also discuss the usage of the sensitivity analysis of the system, provided by the direct differentiation method, for the optimization of in situ monitoring. The sensitivity distribution in space and time assess the location of the measurements points as well as the time of observation needed for reliable identification. Copyright © 2002 John Wiley & Sons, Ltd.
A complex variable solution for a deforming buoyant tunnel in a heavy elastic half‐plane
Authors: Strack O.E. , Verruijt A. 
Published: October 2002

AbstractAn analytical solution is presented for a buoyant tunnel in an elastic half‐plane. The tunnel undergoes a prescribed displacement along its boundary, and the surface of the half‐plane is stress‐free. The solution uses the complex variable method and consists of conformally mapping the hole and half‐plane to an annular region. The complex potentials each contain two logarithmic terms due to the resultant buoyancy force acting on the tunnel, and as a result the displacements at infinity are unbounded. An example is presented for the case of a rigid buoyant tunnel in a half‐plane with gravity loading. Even though the tunnel does not deform, the buoyancy effect can be clearly seen in the contours of the displacements and stresses. Copyright © 2002 John Wiley & Sons, Ltd.
An index policy for a stochastic scheduling model with improving/deteriorating jobs
Authors: Glazebrook K.D. , Mitchell H.M. 
Published: October 2002

AbstractWe consider stochastic scheduling models which have the natural character that jobs improve while being processed, but deteriorate (and may possibly leave the system altogether) while processing is diverted elsewhere. Such restless bandit problems are shown to be indexable in the sense of Whittle. A numerical study which elucidates the strong performance of the resulting index policy is complemented by a theoretical study which demonstrates the optimality of the index policy under given conditions and which develops performance guarantees for the index heuristic more generally. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 706–721, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10036
Network fair bandwidth share using hash rate estimation
Authors: Li Jung‐Shian , Leu Ming‐Shiann 
Published: October 2002

AbstractIn this paper, we evaluate the effectiveness of the current active queue management (AQM) schemes, such as Random Early Detection (RED) and match‐based CHOKe, over traffic with different packet‐size flows and over traffic with mixed adaptive and nonadaptive flows. We find that these schemes allow unfair bandwidth sharing when flows with different packet sizes share a link or when numerous adaptive and nonadaptive flows coexist in a link. In particular, the match‐based schemes present greater unfairness, especially when more nonadaptive flows exist in a shared link. We propose a novel AQM scheme, called Hash Rate Estimation (HRE). The proposed scheme, which works with a FIFO queue, uses per‐active‐flow rate estimation to impose a fair share on each flow. We show that HRE provides better protection than does Fair Random Early Drop (FRED), which uses per‐flow accounting to allocate each flow its fair share by a fixed dropping probability that depends on the flow's buffer use. HRE can support a large number of flows using hash function sorting. In addition, the queue length under HRE is bounded and the characteristics of traffic regulated by HRE are similar to those achieved by the per‐flow fair queuing schemes. © 2002 Wiley Periodicals, Inc.
Isomorphisms of the De Bruijn digraph and free‐space optical networks
Authors: Coudert D. , Ferreira A. , Perennes S. 
Published: October 2002

AbstractThe de Bruijn digraph B(d, D) has degree d, diameter D, dD vertices, and dD+1 arcs. It is usually defined by words of size D on an alphabet of cardinality d, through a cyclic left‐shift permutation on the words, after which the rightmost symbol is changed. In this paper, we show that any digraph defined on words of a given size, through an arbitrary permutation on the alphabet and an arbitrary permutation on the word indices, is isomorphic to the de Bruijn digraph, provided that this latter permutation is cyclic. We use this result to improve from O(dD+1) to
$\Theta(\sqrt{d^{D+1}})$
the number of lenses required for the implementation of B(d, D) by the Optical Transpose Interconnection System proposed by Marsden et al. [Opt Lett 18 (1993), 1083–1085]. © 2002 Wiley Periodicals, Inc.
Using the modified 2nd order incomplete Cholesky decomposition as the conjugate gradient preconditioning
Authors: Kaporin I. E. 
Published: October 2002

AbstractIn this paper, the ‘second‐order’ incomplete triangular factorization (Kaporin, 1998) is considered as a preconditioner for the CG method. Some refinements of the original algorithm are proposed and investigated, which give rise to a more efficient modified incomplete Cholesky 2nd‐order (MIC2) type preconditionings. Numerical results are given for a set of real‐life large‐scale SPD linear systems arising in the finite element modelling of linear elasticity problems which clearly indicate the superiority of the MIC2 preconditionings. Copyright © 2002 John Wiley & Sons, Ltd.
A finite element method using singular functions for the Poisson equation: crack singularities
Authors: Cai Zhiqiang , Kim Seokchan , Woo Gyungsoo 
Published: October 2002

AbstractIn Cai and Kim (SIAM J. Numer. Anal. 2001; 39: 286), we developed and analysed a new accurate finite element method using singular functions for the Poisson equation on a two‐dimensional polygonal domain with re‐entrant corners. This method first computes the regular part of the solution, then stress intensity factors, and finally the solution itself. This note extends this method to the Poisson equation on a domain with cracks and considers a higher‐order method when f∈ H1(Ω). Copyright © 2002 John Wiley & Sons, Ltd.