bluuebunny/crossref_metadata_2025 huggingface dataset:
Communication patterns and technical quality of virtual visits in home care
Authors: Demiris George , Speedie Stuart , Finkelstein Stanley , Harris Ilene
Published: August 2003

Ten patients in a home care study received virtual visits from nurses via analogue video-phones in their homes. They received standard home care services and two virtual visits per week. The visits were video-recorded and then reviewed. The study involved 10 patients and 10 nurses from one urban and three rural home care agencies. Six of the patients had congestive heart failure, three had chronic obstructive pulmonary disease and one required diabetes-related wound care. The average age of the patients was 78 years (SD 12). All but one lived in rural areas. One hundred and twenty-two virtual visits were reviewed for technical quality. Their mean duration was 21 min (range 5-60). The technical quality was given an average rating of 95% (range 57-100%). There were no technical problems in 78 visits (64%); in 10 cases (8%) there was difficulty establishing a connection. A content analysis of 30 of the visits identified 13 themes, such as assessing the patient's clinical status, promotion of compliance with medication and treatment, psychosocial issues, general informal talk and patient education. In general, the technical problems were minor and did not appear to interfere with care.
Preliminary experience of allied health assessments delivered face to face and by videoconference to a residential facility for elderly people
Authors: Guilfoyle Clare , Wootton Richard , Hassall Stacey , Offer Jann , Warren Margo , Smith Debbie
Published: August 2003

We investigated whether allied health assessments carried out via videoconferencing were comparable to assessments carried out face to face. Five allied health therapists (in dietetics, occupational therapy, physiotherapy, podiatry and speech pathology) conducted an assessment of 12 high-dependency residents both face to face and by videoconferencing. On a five-point Likert scale, the therapists' mean ratings for the efficiency and suitability of videoconferencing for assessment were significantly lower than for face to face. Their mean rating for the adequacy of their care plans was also significantly lower for videoconferencing than for face to face. However, in each case the dietician's assessments did not differ significantly between the two modalities. In 35 cases out of 60, two independent raters agreed that the therapists' care plans after the videoconferencing and face-to-face assessments were the same. However, the level of agreement between raters was only moderate (kappa=0.31). Despite the therapists' (natural) preference for face-to-face working, care plans formulated via videoconferencing were reasonably similar to those formulated in face-to-face assessment. Allied health assessments carried out by videoconferencing would therefore seem to be feasible.
A new approach to real‐time training of dynamic neural networks
Authors: Chowdhury Fahmida N.
Published: August 2003

A fast, efficient and new way of real‐time training of dynamic neural networks is presented in this paper. The proposed method would be suitable for training neural networks for real‐time input–output modelling of uncertain dynamic systems. The training method proposed in this paper is unique in the sense that only the outer layer weights are updated; the hidden layer weights are chosen randomly at the beginning of the process, and left unchanged. The outer layer weights are estimated with an ordinary Kalman filter. This provides a learning rate which is an optimally time‐varying vector. Results of computer simulation experiments, including a comparison with conventional backpropagation, are presented. Copyright © 2003 John Wiley & Sons, Ltd.
Intelligent control using multiple neural networks
Authors: Chen Lingji , Narendra Kumpati S.
Published: August 2003

In this paper a framework for intelligent control is established to adaptively control a class of non‐linear discrete‐time dynamical systems while assuring boundedness of signals. A linear robust adaptive controller and multiple non‐linear neural network based adaptive controllers are used, and a switching law is suitably defined to switch between them, based upon their performances in predicting the plant output. Boundedness of signals is established with minimum requirements on the parameter adjustment mechanisms of the neural network controllers, and thus the latter can be used in novel ways to better detect changes in the system being controlled, and to initiate fast adaptation. Simulation studies show the effectiveness of the proposed approach. Copyright © 2003 John Wiley & Sons, Ltd.
Median and musculocutaneous nerves: Variant formation and distribution
Authors: Saeed Muhammad , Rufai Amin A.
Published: August 2003

An unusual formation of the median and musculocutaneous nerves was observed during routine dissection of the left upper limb of a 60‐year‐old Caucasian male cadaver. The median nerve was formed by the fusion of three roots, two from the lateral and one from the medial cord of the brachial plexus. The variant lateral root of the median nerve followed an anomalous course, crossing anterior to the distal part of the axillary artery. Moreover, in the distal half of the arm, the median nerve contributed a communicating branch to the musculocutaneous nerve. Injury to such a variant median nerve in the proximal arm may lead to paresthesia along the preaxial border of the forearm, weakness of elbow flexion, in addition to other manifestations of median nerve injury. The developmental and clinical significance of this anomaly is discussed. Clin. Anat. 16:453–457, 2003. © 2003 Wiley‐Liss, Inc.
Avulsion fracture of the pelvis: Separation of the secondary ossification center in the superior margin of the acetabulum
Authors: Nan̆ka O. , Havránek P. , Pes̆l T. , Dutka J.
Published: August 2003

A 13‐year‐old female sustained a rare avulsion fracture of the secondary ossification center in the superior margin of the acetabulum as the result of contraction of the reflected head of the rectus femoris muscle. Diagnosis was made from plain films and CT scans with 3D image reconstruction. The patient was treated non‐operatively by bed rest with semiflexion of the hip and knee, and appropriate analgesia. Clin. Anat. 16:458–460, 2003. © 2003 Wiley‐Liss, Inc.
High prevalence of tarsal coalitions and tarsal joint variants in a recent cadaver sample and its possible significance
Authors: Rühli F.J. , Solomon L.B. , Henneberg M.
Published: August 2003

Tarsal coalitions (TC) are defined as fibrous (beyond normal ligaments), cartilaginous, or osseous unions of at least two tarsal bones. Most of the clinical studies report the prevalence of TC as <1%, but they disregard the asymptomatic coalitions. Because TC have been associated with pathologic conditions, including degenerative arthritic changes, knowledge of their prevalence has clinical importance. The aim of our study was to establish the prevalence of TC and tarsal joint variants. A total of 114 feet from 62 cadavers (average age = 78 years) without obvious foot pathologies were dissected at the Department of Anatomical Sciences, The University of Adelaide. Ten non‐osseous TC in eight subjects were identified: two talocalcaneal and eight calcaneonavicular (occurred twice bilaterally). Variant calcaneonavicular and cuboideonavicular joints were found in 8% and 31% of feet, respectively. Other joint variants included a variable number of talocalcaneal joint surfaces and sesamoid bones. No secondary TC (due to trauma, infections, or neoplasm) were found. Our study demonstrated that the overall prevalence of TC is higher (13%) than previously thought; tarsal joint variations (39%) and sesamoid bones (42%) were common as well. The supposed secular increase in the prevalence of TC as well as the high number of anatomical variants could reflect a short‐term response to altered life‐style or a microevolutionary trend due to relaxed selection. Clin. Anat. 16:411–415, 2003. © 2003 Wiley‐Liss, Inc.
Collo‐diaphysial angle of the femur in East African subjects
Authors: Igbigbi P.S.
Published: August 2003

The collo‐diaphysial angle of East African subjects was investigated using 860 unilateral anteroposterior radiographs of the hip from 400 Ugandan and 460 Kenyan subjects, aged between 18 and 65 years using the standard techniques of Singh and Singh (1975). The angle ranged from 125–144° with a mean of 133.3° and a standard deviation (SD) of 5.3° for Ugandan males; and 119–139°, mean 123.4°, SD 5.8° for Ugandan females. The Kenyan values were 125–159°, mean 140.2°, SD 6.2° for males; and 117–134°, mean 125.7°, SD 5.1° for females, respectively. There were significant differences between males and females in both groups as well as between Ugandan and Kenyan males (P < 0.05). Using the demarking points method, only 19.0% of male Ugandans, 41.7% of male Kenyans, and 18.2% of female Kenyans could be identified by gender. This study documents for the first time the collo‐diaphysial angle of East African subjects and has further confirmed that the angle is wider in men than women. Clin. Anat. 16:416–419, 2003. © 2003 Wiley‐Liss, Inc.
Echocardiographic and morphologic examination of left ventricular false tendons in human and animal hearts
Authors: Kervancioğlu M. , Őzbağ D. , Kervancioğlu P. , Hatipoğlu E.S. , Kilinç M. , Yilmaz F. , Deniz M.
Published: August 2003

False tendons are thin, fibrous or fibromuscular structures that traverse the cavity of the left ventricle with no connection to the valvular cusps; they may be single or multiple. We retrospectively analyzed echocardiograms for the prevalence of false tendons in the hearts of 368 (231 male, 137 female) newborns, infants, and children (mean age = 6.28 ± 4.32 years) who were referred for echocardiography because of suspected acquired or congenital heart disease, but in whom no cardiac pathology was found. In addition, we studied the prevalence of false tendons in 90 hearts from three species of animals (dog, sheep, goat) and eight cadaveric human hearts. In our echocardiographic study, false tendons were detected in 97 of 368 hearts (26.4%). In our gross morphologic studies, false tendons were observed in most of the animal and human hearts: they were present in 5 of 8 (62.5%) human hearts, 14 of 20 (70%) dog hearts, 41 of 50 (82%) sheep hearts, and 16 of 20 (80%) goat hearts. The overall prevalence in animal hearts was 71 of 90 (78.8%). Histologic examination showed the false tendons to be composed of cardiac muscle, blood vessels, fibrous tissue, and Purkinje cells. The possible role of false tendons in innocent murmurs, cardiac rhythm disorders, or left ventricular dysfunction is discussed. Clin. Anat. 16:389–395, 2003. © 2003 Wiley‐Liss, Inc.
Scalable causal message logging for wide‐area environments
Authors: Bhatia Karan , Marzullo Keith , Alvisi Lorenzo
Published: August 2003

Wide‐area systems are gaining in popularity as an infrastructure for running scientific applications. From a fault tolerance perspective, these environments are challenging because of their scale and their variability. Causal message logging protocols have attractive properties that make them suitable for these environments. They spread fault tolerance information around in the system providing high availability. This information can also be used to replicate objects that are otherwise inaccessible because of network partitions.

However, current causal message logging protocols do not scale to thousands or millions of processes. We describe the Hierarchical Causal Message Logging Protocol (HCML) that uses a hierarchy of shared logging sites, or proxies, to significantly reduce the space requirements as compared with existing protocols. These proxies also act as caches for fault tolerance information and reduce the overall message overhead by as much as 50%. HCML also leverages differences in bandwidth between processes that reduces overall message latency by as much as 97%. Copyright © 2003 John Wiley & Sons, Ltd.
Achieving portable and efficient parallel CORBA objects
Authors: Denis Alexandre , Pérez Christian , Priol Thierry
Published: August 2003

With the availability of Computational Grids, new kinds of applications are emerging. They raise the problem of how to program them on such computing systems. In this paper, we advocate a programming model based on a combination of parallel and distributed programming models. Compared to previous approaches, this work aims at bringing single program multiple data (SPMD) programming into CORBA in a portable way. For example, we want to interconnect two parallel codes by CORBA without modifying either CORBA or the parallel communication API. We show that such an approach does not entail any loss of performance compared to previous approaches that required modification to the CORBA standard. Moreover, using an ORB that is able to exploit high‐performance networks, we show that portable parallel CORBA objects can efficiently make use of such networks. Copyright © 2003 John Wiley & Sons, Ltd.
HA‐PSLS: a highly available parallel single‐level store system
Authors: Kermarrec Anne‐Marie , Morin Christine
Published: August 2003

Parallel single‐level store (PSLS) systems integrate a shared virtual memory and a parallel file system. They provide programmers with a global address space including both memory and file data. PSLS systems implemented in a cluster thus represent a natural support for long‐running parallel applications, combining both the natural shared memory programming model and a large and efficient file system.

However, the need to tolerate failures in such a system increases with the size of applications. In this paper we present a highly‐available parallel single level store system (HA‐PSLS), which smoothly integrates a backward error recovery high‐availability mechanism into a PSLS system. Our system is able to tolerate multiple transient failures, a single permanent failure, and power cut failures affecting the whole cluster, without requiring any specialized hardware. For this purpose, HA‐PSLS relies on a high degree of integration (and reusability) of high‐availability and standard features. A prototype integrating our high‐availability support has been implemented and we show some performance results in the paper. Copyright © 2003 John Wiley & Sons, Ltd.
A distributed object infrastructure for interaction and steering
Authors: Muralidhar Rajeev , Parashar Manish
Published: August 2003

This paper presents the design, implementation and experimental evaluation of DIOS (Distributed Interactive Object Substrate), an interactive object infrastructure to enable the runtime monitoring, interaction and computational steering of parallel and distributed applications. DIOS enables application objects (data structures, algorithms) to be enhanced with sensors and actuators so that they can be interrogated and controlled. Application objects may be distributed (spanning many processors) and dynamic (be created, deleted, changed or migrated). Furthermore, DIOS provides a control network that interconnects the interactive objects in a parallel/distributed application and enables external discovery, interrogation, monitoring and manipulation of these objects at runtime. DIOS is currently being used to enable interactive visualization, monitoring and steering of a wide range of scientific applications, including oil reservoir, compressible turbulence and numerical relativity simulations. Copyright © 2003 John Wiley & Sons, Ltd.
Winner‐relaxing and winner‐enhancing Kohonen maps: Maximal mutual information from enhancing the winner
Authors: Claussen Jens Christian
Published: August 2003

The magnification behavior of a generalized family of self‐organizing feature maps, the winner relaxing and winner enhancing Kohonen algorithms is analyzed by the magnification law in the one‐dimensional case, which can be obtained analytically. The winner‐enhancing case allows to achieve a magnification exponent of one and therefore provides optimal mapping in the sense of information theory. A numerical verification of the magnification law is included, and the ordering behavior is analyzed. Compared to the original self‐organizing map and some other approaches, the generalized winner enforcing algorithm requires minimal extra computations per learning step and is conveniently easy to implement. © 2003 Wiley Periodicals, Inc.
Significance of joint‐spike events based on trial‐shuffling by efficient combinatorial methods
Authors: Pipa Gordon , Diesmann Markus , Grün Sonja
Published: August 2003

The assembly hypothesis suggests that information processing in the cortex is mediated by groups of neurons expressed by their coordinated spiking activity. Thus, the unitary events analysis was designed to detect the presence of conspicuous joint‐spike events in multiple single‐unit recordings and to evaluate their statistical significance. The null hypothesis of the associated test assumes independent Poisson processes and leads to parametric significance estimation. In order to allow for arbitrary processes here we suggest to base the significance estimation on trial shuffling and resampling. In this scheme the null hypothesis is implemented by combining spike trains from nonsimultaneous trials and counting the joint‐spike events. The coincidence distribution serving for the significance estimation is generated by repetitive resampling. The number of all possible recombinations, however, grows dramatically with the number of trials and neurons and thus is not practical for a user‐interactive implementation of the analysis. We have suggested a Monte‐Carlo‐based resampling procedure and demonstrated that the procedure yields an appropriate estimate of the distribution and reliable significance estimation. In contrast, here, we present an exact solution. Rewriting the statistical problem in terms of certain macrostates, we are able to systematically sample the coincidence counts from all trial combinations. In addition we restrict the generating process to those counts forming the relevant tail of the distribution. The computationally effective implementation uses the concept of partitions. © 2003 Wiley Periodicals, Inc.
Complex dynamics is abolished in delayed recurrent systems with distributed feedback times
Authors: Thiel Andreas , Schwegler Helmut , Eurich Christian W.
Published: August 2003

Feedback systems with a single delay time—as described by delay‐differential equations—are known to exhibit various dynamical behaviors including complex oscillations and chaos. Here we show that the consideration of a broad distribution of delay times instead of a single delay results in a shift of the dynamical bifurcations toward higher parameter values, yielding a larger set of parameters with fixed point behavior or simple oscillatory behavior. We demonstrate similar phenomena in three different systems: neuronal feedback in the hippocampus, white blood cell production, i.e., the Mackey‐Glass equation, and population dynamics in theoretical ecology. Our results suggest that the observed simplification of the dynamics is independent of the shape of the delay distribution and the precise nature of the feedback. The existence of distributed delay times may yield a mechanism to avoid irregular fluctuations in biological feedback systems. © 2003 Wiley Periodicals, Inc.
Genetic distance in sequence space of evolving populations
Authors: Manffra Elisangela Ferretti , Kantz Holger , Ragwitz Mario
Published: August 2003

A genome‐based measure for the distance between two populations is introduced. It fulfills the triangular inequality and can be easily computed, when the genetic sequences of a large number of individuals in two different populations are given. We use this distance for a study of mutating populations evolving under selective pressure, which are “living” on a computer. As a particular result, we find that evolution is diffusive. We include a comparison of our novel concept and the notion of genomic complexity of populations introduced by Adami et al. (Adami, C.; Ofria, C.; Collier, T.C. Evolution of biological complexity. Proc Natl Acad Sci USA 2000, 97, 4463–4468.) © 2003 Wiley Periodicals, Inc.
Prisoner's dilemma and public goods games in different geometries: Compulsory versus voluntary interactions
Authors: Hauert Christoph , Szabó György
Published: August 2003

The evolution of cooperation among unrelated individuals in human and animal societies remains a challenging issue across disciplines. In this context, two models have attracted most attention: the prisoner's dilemma for pairwise interactions and the public goods game for group interactions. The two games share many features as demonstrated by the close linkage of their cores. In spatially structured systems with individuals arranged on a lattice we investigate effects of group size and lattice geometry on the success of cooperators and defectors in compulsory and voluntary interactions. The geometry (square versus honeycomb), i.e., the connectivity turns out to have surprisingly pronounced and robust effects on the fate of cooperators. Apparently they thrive more easily on honeycomb lattices. As expected, it becomes increasingly difficult to promote cooperation in sizable groups but voluntary participation significantly lowers the threshold for persistent cooperative behavior. In fact, this effect is even more pronounced for larger groups. The risk avoiding option to not participate provides additional protection to clusters of cooperators against exploitation and introduces rock‐scissors‐paper‐type cyclic dominance, which gives rise to intriguing spatio‐temporal patterns. © 2003 Wiley Periodicals, Inc.
Adaptive online learning of generative stochastic models
Authors: Stiller J. C.
Published: August 2003

In online learning problems to choice of the learning rate, the weight given to new observations with respect to the knowledge gained from old ones, is a difficult problem. A novel algorithm for the adaptive, i.e., data‐dependent choice of the learning rate is presented. It is based on the idea of maximum likelihood estimation. In contrast to other approaches it does not rely on the stochastic independence of the observed data, the stationarity of the data source or a priori information about parameter changes. This makes it well suited for the analysis of ongoing nonstationary dynamic processes. It can be applied to the online learning of various different generative stochastic models. We present the adaptive online learning of Hidden Markov Models. © 2003 Wiley Periodicals, Inc.
Time‐domain analysis of conducting wire antennas and scatterers
Authors: Jung Baek Ho , Sarkar Tapan Kumar , Ji Zhong , Chung Young‐seek
Published: August 2003

In this work, a new method is presented for analyzing the transient electromagnetic response from conducting wire structures using the time‐domain integral equation (TDIE). Instead of the conventional marching‐on in time (MOT) technique, this solution method is based on Galerkin's method, which involves separate spatial and temporal testing procedures. Piecewise triangle basis functions have been used for spatial expansion and testing functions for arbitrarily shaped wire structures. The time‐domain variation is approximated by a temporal basis‐function set that is derived from the Laguerre functions. These basis functions are also used for temporal testing. The method presented in this paper results in very accurate and stable transient responses from wire antennas and scatterers. Representative numerical results are presented and compared with available data. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 433–436, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11082
Near‐field coupling between a printed antenna and a Fabry Perot resonator: Experimental study of the radiation properties at millimeter wave frequencies
Authors: Sauleau Ronan , Coquet Philippe , Matsui Toshiaki
Published: August 2003

Compact focusing antennas, consisting of a Fabry–Perot (FP) cavity coupled to a printed source, are studied in the 60‐GHz band. Several configurations of antennas, including plane‐parallel or plano‐convex cavities excited by a patch antenna or an array, are considered and compared. In particular, their radiation characteristics are investigated experimentally as a function of the operating frequency and the thickness of the free‐space coupling region separating the primary radiator from the resonator. The optimum coupling conditions are also defined to maximize the efficiency and minimize the sidelobe level. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 438–443, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11084
Characteristic basis function method: A numerically efficient technique for analyzing microwave and RF circuits
Authors: Kwon Soon Jae , Du Kai , Mittra Raj
Published: August 2003

In this paper, we present an efficient electromagnetic analysis of planar microstrip structures, called the characteristic basis function method (CBFM). In this method, the original problem geometry is segmented into smaller regions called sections, and high‐level basis functions are generated to represent the electromagnetic characteristics of these sections. These basis functions are referred to as the characteristic basis functions (CBFs), and their use leads to a reduced matrix equation. Since the method only requires the solution of small‐size matrix equations, associated with isolated domains, the computational burden is relieved, and an acceleration of the solve time is achieved. The efficiency of this method is demonstrated via several examples, including a filter and an amplifier circuit. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 444–448, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11085
Wideband dipole arrays using non‐Foster coupling
Authors: Hansen R.C.
Published: August 2003

A planar array of dipoles, with collinear dipoles connected by lumped negative inductances, is simulated by the piecewise sinusoidal method of moments. Over a multi‐octave bandwidth, the gain is close to the area gain, which is a remarkable result. The non‐Foster couplings smooth out and increase the current at low frequencies. Recent advances in transistor circuits and topology allow this new array to be considered. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 453–455, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11087
Slot antenna fed by a CPW line with tapered transition
Authors: Zheng Guiping , Kishk Ahmed A. , Glisson Allen W. , Yakovlev Alexander B.
Published: August 2003

A tapered coplanar waveguide (CPW) transition is proposed in order to facilitate the connection between a slot antenna and coaxial connector. The broadband bow‐tie slot antenna is considered as an example in this design. The tapered transition is utilized to optimize the connection of two 50Ω CPW lines with different widths. A narrow CPW line is connected to the slot‐antenna feed point and the wide CPW line is connected to the coaxial SMA connector for measurement purposes. The tapered transition proposed here results in a negligible reflection in the CPW feed when its length is approximately λ/20. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 465–467, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11091
Polarization‐independent and electronically tunable Fabry Perot etalons with cross‐orthogonal liquid‐crystal layers
Authors: Lin Kuen‐Cherng , Chuang Wei‐Ching
Published: August 2003

A novel structure of a polarization‐independent and electronically tunable Fabry–Perot interferometer is proposed. It consists of double layers of homogeneously aligned liquid‐crystal films with an orthogonal buffing direction. Both theoretical and experimental results show that a pure resonant wavelength with excellent polarization‐independent properties, was obtained. Our devices demonstrate power fluctuations of less than 0.5 dB and extinction ratios of up to 7 dB. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 475–477, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11093
Design of an isolated capacitor cell for three‐dimensional RF circuit integration
Authors: Kim Dae Jun , Lee Young Chul , Choi Byeong Gun , Eun Ki Chan , Park Chul Soon
Published: August 2003

A compact multilayer capacitor cell isolated with perforated ground was designed and fabricated using low‐temperature ceramic co‐firing (LTCC) technology for three‐dimensional (3D) RF circuit application. The vertical transmission from any interferer placed 114 μm above the capacitor cell and the lateral transmission from any interferer 300 μm apart from the cell were controlled below −20 dB up to 15 GHz. The 2.8‐pF capacitor shielded with perforated ground of 600‐μm square edge and 800‐μm pitch revealed a self‐resonant frequency (SRF) of 7.6 GHz and Q factor of over 190 up to 3 GHz, which is an improvement of SRF by 0.8 GHz and Q factor by 224%, compared to the capacitor with a conventional blanket ground. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 484–486, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11096
Double Volterra series approach to FET mixers
Authors: Crespo‐Cadenas Carlos , Reina‐Tosina Javier
Published: August 2003

A double Volterra series approach to analyze nonlinear microwave circuits is presented, with special emphasis on FET mixers. Considering a FET as a circuit with two input ports, a procedure to obtain closed‐form expressions for nonlinear transfer functions is presented. Based on this approach, the known time‐varying Volterra series technique can be demonstrated. Calculated conversion loss and two‐tone IMD for a FET‐resistive mixer are successfully compared with already published data. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 486–488, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11097
A simple approach towards the design and optimization of a C‐band injection‐locked amplifier
Authors: Chakravarty T. , Kumar Arun , Basu A. K.
Published: August 2003

In this paper, a simple design and optimization approach for a C‐band injection‐locked amplifier using a FET dielectric resonator oscillator is presented. Considerations such as frequency stability, mechanical tuning, repeatability, and low cost led to the choice of a dielectric resonator oscillator (DRO) as the injection‐locked amplifier (ILA). Here the heights of the DR and the spacer are experimentally optimized to obtain wider tunability (≈4.9%) with a power flatness of ±1 dB at power output levels of +30 dBm. The simplicity of the design approach is outlined and optimization technique discussed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 488–491, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11098
A broadband microstrip antenna utilizing an integrated rectangular‐channel‐shaped feed
Authors: Bancroft Randy
Published: August 2003

A broadband rectangular microstrip antenna, which utilizes a rectangular channel feed to obtain 25% impedance bandwidth, is described. A finite‐difference time‐domain (FDTD) analysis of the element's input impedance and radiation patterns versus measurement are presented. The FDTD impedance analysis utilizes a simplified coaxial probe feed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 491–494, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11099
Bragg reflectors containing left‐handed materials
Authors: Ruppin R.
Published: August 2003

Effects of the frequency‐dependence of the permeability and permittivity of a left‐handed material (LHM), when used as one of the components of a Bragg reflector, are investigated. It is found that typical broad Bragg reflectivity peaks appear in the frequency range in which the material is not left‐handed. Inside the LHM range, the Bragg peaks are very narrow and of low intensity. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 494–495, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11100
Dual‐frequency and broadband characteristics of hybrid coupled slot antennas fed by coplanar waveguide
Authors: Chen Jin‐Sen
Published: August 2003

A simple design of a hybrid coupled slot antenna, fed by coplanar waveguide with dual‐frequency or broadband operation, is presented. The proposed antenna is constructed by a coplanar waveguide (CPW) capacitively coupled slot‐loop antenna and a CPW inductively coupled dipole slot antenna. The dimensions of the two slot antennas decide the two resonant frequencies of the proposed antenna, respectively. Results show that the impedance bandwidth of the proposed broadband slot antenna is about 35%. Details of the proposed dual‐frequency and broadband designs are described and experimental results are presented and discussed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 496–498, 2003; Published online in Wiley InterScience (www.interscience.wiley.com).
A foam‐base surface‐mountable shorted monopole antenna for WLAN application
Authors: Su Saou‐Wen , Wu Tzuenn‐Yih , Cheng Yuan‐Tung , Wong Kin‐Lu
Published: August 2003

A surface‐mountable shorted monopole antenna, constructed by folding a branch‐line metal strip onto a foam base for 2.4/5.2/5.8‐GHz WLAN operation, is presented. The branch‐line metal strip is comprised of a longer arm, a shorter arm, and a matching arm. The longer and shorter arms generate, respectively, a lower resonant mode covering the 2.4‐GHz band (2400–2484 MHz) and an upper resonant mode covering the 5.2‐GHz (5150–5350 MHz) and 5.8‐GHz (5725–5875 MHz) bands, and good impedance matching for frequencies across the two resonant modes is easily achieved by adjusting the distance between the feeding point and the shorting point in the matching arm. Experimental results of a constructed prototype of the proposed antenna are presented. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 501–503, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11103
Group‐velocity matched‐fiber Raman wavelength converter for the flexible optical communications network
Authors: Tang Ming , Ghafouri‐Shiraz H.
Published: August 2003

The feasibility of a group‐velocity matched‐fiber Raman wavelength converter using extended birefringent fiber has been demonstrated, in which high‐power pumping laser diodes are used to achieve sufficient four‐wave mixing (FWM) Raman conversion. Based on our proposed novel model, the power intensity and temporal properties of the converted wave (10 Gb/s and 20 Gb/s, from C‐band to L‐band) have been demonstrated. The ultra‐wide Raman gain spectrum and the tunability of the fiber birefringence make our model extremely suitable for broadband wavelength‐convertible lightwave communication. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 504–506, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11104
Multi‐frequency characteristics of annular‐ring slot antennas
Authors: Chen Jin‐Sen
Published: August 2003

The design of an annular‐ring slot antenna for obtaining multi‐frequency operation using a coplanar waveguide feed (CPW) or microstrip line feed is presented. The operating frequencies are obtained by means of multiple radiating elements. Details of the proposed designs are investigated by experimental as well as theoretical studies. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 506–511, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11105
Parallel‐plate waveguides with Kronig Penney morphology as photonic band‐gap filters
Authors: Gómez Álvaro , Lakhtakia Akhlesh , Solano Miguel A. , Vegas Angel
Published: August 2003

Guided wave propagation in a parallel‐plate waveguide with Kronig–Penney morphology is analyzed. Modes in the photonic band‐gap (PBG) structure can be classified as either transverse electric or transverse magnetic with respect to the propagation direction. Above the modal cut‐off frequencies, band gaps exist where propagation is forbidden. The locations and the widths of the band gaps depend on modal order, waveguide height, and the permittivity contrast and relative volumetric proportion of the two materials constituting the unit cell of the PBG structure. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 511–514, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11106
Advances in sputter depth profiling using AES
Authors: Hofmann Siegfried
Published: August 2003

Sputter depth profiling using AES is a routinely applied method in surface, interface and thin‐film analysis. After about 30 years of constant progress the present state is characterized by improved instrumentation, e.g. sample rotation capabilities and low‐energy ion guns, as well as by improved quantification methods for the raw data depth profiles. Profile quantification by reconstruction of the original in‐depth distribution of composition using the so‐called (atomic) mixing–roughness–information depth (MRI) model has proved to be a powerful tool for extracting more precise and extended information of the measured profiles, e.g. quantification with submonolayer accuracy, intrinsic determination of the sputtering rate and determination of localized interdiffusion coefficients as low as 10−22 m2 s−1 were obtained. Because the MRI model is based on physically well‐defined parameters, it can be applied successfully to other profiling techniques such as SIMS or GDOES. Although in many cases the MRI model can be applied in its original version, some materials require modification by a preferential sputtering coefficient. Further modifications will be necessary to take care of non‐linear effects in the concentration dependence and in the compositional distribution within the atomic mixing zone. In summary, quantitative depth profiling using AES has now attained an advanced stage, where its combination with the MRI model is being introduced in commercial instrument software. Copyright © 2003 John Wiley & Sons, Ltd.
Surface characterization and depth profile analysis of glasses by r.f. GDOES
Authors: Le Coustumer Philippe , Motelica‐Heino Mikael , Chapon Patrick , François Saint‐Cyr Hugues , Payling Richard
Published: August 2003

The characterization of surfaces, interfaces and interphases in glasses is analytically challenging and may benefit from recent developments in radiofrequency glow discharge optical emission spectroscopy (r.f. GDOES) applied to non‐conductive materials. Thus, the main thrust of this study is to evaluate the potential of r.f. GDOES for the characterization of glass surfaces, physical heterogeneities such as discrete layers and continuous interphases and the distribution of elements in glass materials. Model glasses with increasing structural and chemical complexity thus were analysed using a Jobin Yvon GDOES system (5000 RF): the glasses included a multilayered glass (triple‐coated glass), two photoreactive glasses (with potential chemical diffusion gradients) and acid‐leached glass with an alteration layer. Concurrently, surface characterization of the glasses was conducted using scanning electron microscopy or transmission electron microscopy with energy‐dispersive x‐ray imaging to assess the chemical and physical gradients in the materials and to investigate the glow discharge sputtering process. From this the capability of r.f. GDOES for elemental depth profiling in glass materials is established. However, although the sputtering rates for glass are greatly reduced compared with conductive materials (∼2 nm s−1 compared with 50–150 nm s−1 for metals), r.f. GDOES offers good spatial depth resolution (nm) and elemental sensitivity for several applications, such as the characterization of interfaces or interphases and the determination of chemical gradients in glasses. Furthermore, the technique distinguishes submicrometre discrete layers in the coated glass, and the diffusion of elements within glass matrices may be monitored. Copyright © 2003 John Wiley & Sons, Ltd.
The effect of total hip arthroplasty surgical approach on gait
Authors: Madsen Michael S. , Ritter Merrill A. , Morris Harold H. , Meding John B. , Berend Michael E. , Faris Phillip M. , Vardaxis Vassilios G.
Published: August 2003

This study examined the effect of the surgical approach used in total hip arthroplasty (THA) on gait mechanics six months following surgery. Quantitative gait analysis was performed on 29 subjects: 10 anterolateral (A‐L) and 10 posterolateral (P‐L) THA patients and nine able‐bodied, velocity‐matched subjects. Discriminant function analysis was used to determine the distinction of the groups with respect to sagittal plane hip range of motion, index of symmetry, trunk inclination, pelvic drop, hip abduction, and foot progression angles. The A‐L group had the largest trunk inclination (3.0 ± 2.4°) and the smallest hip range of motion (34.0 ± 7.4°). Both THA groups demonstrated greater asymmetry as expressed by the smaller symmetry index (0.97 ± 0.04 for A‐L and 0.98 ± 0.05 for the P‐L) than the able‐bodied group (0.99 ± 0.01). The classification procedure correctly classified 89% of the control group cases, 90% of the A‐L cases, and 50% of the P‐L cases. These results support the conclusion that six months following surgery, the gait of the majority (85%) of THA patients has not returned to normal. The A‐L patients displayed distinct gait patterns, while a small percentage (30%) of the P‐L patients demonstrated normal gait. While these differences are statistically significant, the clinical significance is unknown and linked to the duration that they persist. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Quadriceps femoris muscle weakness and activation failure in patients with symptomatic knee osteoarthritis
Authors: Lewek Michael D. , Rudolph Katherine S. , Snyder‐Mackler Lynn
Published: August 2003

Purpose: Quadriceps weakness is common in patients with knee osteoarthritis (OA), and has been attributed to failure of voluntary activation. Methodological differences may have contributed to previous reports of extensive failure of voluntary activation in patients with osteoarthritis. The purpose of this study was to determine the extent of quadriceps muscle weakness and activation failure in middle aged patients with symptomatic medial knee osteoarthritis using maximum voluntary isometric contractions (MVIC) and a burst superimposition technique.

Methods: Measurements of quadriceps MVIC and extent of voluntary activation were made in 12 subjects with knee OA and 12 similarly aged uninjured subjects. Voluntary activation was tested by superimposing a train of electrical stimulation on a maximal effort volitional contraction of the quadriceps muscle.

Results: The group of subjects with knee OA had significantly less quadriceps strength relative to body mass index (BMI) than the group of control subjects (p = 0.010). No difference in voluntary activation was observed (p = 0.233), however, 50% of the OA group, and only 25% of the control group failed to fully activate the quadriceps.

Discussion: The finding of quadriceps weakness is consistent with past literature. Providing adequate instruction, feedback, and several attempts to maximally contract the muscle likely yielded greater volitional activation (thus less activation failure) than had been reported previously. This finding has implications for the rehabilitation of weakened quadriceps in patients with knee osteoarthritis. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
The effects of patient age on human osteoblasts' response to Ti–6Al–4V implants in vitro
Authors: Zhang Hai , Lewis Courtland G. , Aronow Michael S. , Gronowicz Gloria A.
Published: August 2003

Osseointegrated implants are a common therapy for the elderly population as lifespan increases. Understanding the effects of age and sex on osseointegration is important for successful implant therapy. Therefore, the response of primary human osteoblasts (HOB) to implant materials was studied. HOBs were obtained by outgrowth of cells from bone from orthopaedic procedures and categorized as Young (Y), < 15; Middle (M), 30–50; and Old (O), > 60 years old. Initially the HOB phenotype was determined on tissue culture plastic. Alkaline phosphatase (ALP) staining and activity were significantly increased in HOBs from older patients. Message levels of type I collagen (COL), bone sialoprotein (BSP) and ALP were significantly higher (from 2.3‐ to 3.8‐fold) in Y subjects compared to M and O patients at 2 weeks. Studies of the response of HOBs to implant materials were undertaken using Ti–6A1–4V disks prepared in a manner similar to orthopaedic implants. A 1.4‐fold (p < 0.05) increase in cell attachment was found in HOBs from Y compared with O in female subjects but not in male subjects. Cell proliferation at 24 h was not significantly different by age or sex, nor was DNA content different at 2 and 4 weeks. Mineralization in HOB‐implant cultures was 2.3‐fold higher in Y than in O, and 1.7‐fold higher in Y compared to M HOBs from female but not male subjects at 4 weeks. Northern blot and RT‐PCR analysis at 2 weeks of culture showed significantly higher levels (1.6–2.3‐fold) of COL, BSP, and osteocalcin (OC) mRNAs in Y HOBs compared to M and O HOBs from female subjects. We conclude that human osteoblasts from older female patients have a decreased ability to form bone on implants. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Microcirculatory effects of pulsed electromagnetic fields
Authors: Smith Thomas L. , Wong‐Gibbons Donna , Maultsby Jane
Published: August 2003

Purpose: Pulsed electromagnetic fields (PEMF) are used clinically to expedite healing of fracture non‐unions, however, the mechanism of action by which PEMF stimulation is effective is unknown. The current study examined the acute effects of PEMF stimulation on arteriolar microvessel diameters in the rat cremaster muscle. The study hypothesis was that PEMF would increase arteriolar diameters, a potential mechanism involved in the healing process.

Methods: Local PEMF stimulation/sham stimulation of 2 or 60 min duration was delivered to the cremaster muscle of anesthetized rats. Arteriolar diameters were measured before and after stimulation/sham stimulation using intravital microscopy. Systemic hemodynamics also were monitored during PEMF stimulation.

Results: Local PEMF stimulation produced significant (p< 0.001) vasodilation, compared to pre‐stimulation values, in cremasteric arterioles in anesthetized rats (n= 24). This dilation occurred after 2 min of stimulation (9% diameter increase) and after 1 h of stimulation (8.7% diameter increase). Rats receiving “sham” stimulation (n= 15) demonstrated no statistically significant change in arteriolar diameter following either “sham” stimulation period. PEMF stimulation of the cremaster (n= 4 rats) did not affect systemic arterial pressure or heart rate, nor was it associated with a change in tissue environmental temperature.

Conclusions: These results support the hypothesis that local application of a specific PEMF waveform can elicit significant arteriolar vasodilation. Systemic hemodynamics and environmental temperature could not account for the observed microvascular responses. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.