bluuebunny/crossref_metadata_2025 huggingface dataset:
Cryopreservation alters membrane sulfhydryl status of bull spermatozoa: Protection by oxidized glutathione
Authors: Chatterjee Suvro , de Lamirande Eve , Gagnon Claude
Published: August 2002

Cryopreservation induces extensive biophysical and biochemical changes in the membrane of spermatozoa that ultimately decrease the fertility potential of the cells. Sulfhydryl groups of sperm proteins regulate a number of activities of the cells. Qualitative and quantitative analyses of sulfhydryl groups in the sperm membrane were performed by fluorescence microscopy, fluorimetry and electrophoresis. Fluorimetric analysis using 5‐iodoacetamidofluoresceine indicated a two‐fold increase in the content of sulfhydryl groups in sperm membrane after a freezing/thawing cycle. Electrophoresis of Triton‐soluble sperm proteins after labeling with 3‐(N‐maleimidylpropionyl) biocytin indicated that proteins of 40–65 and 34 kDa range expose more sulfhydryl groups after cooling at 4°C and freezing/thawing. Cryopreservation of spermatozoa changed the distribution pattern of sulfhydryl groups on sperm surface measured with fluorescence microscopy using 5‐iodoacetamidofluoresceine. The percentage of spermatozoa labeled at the level of the mid‐piece decreased by 50 and 90% after cooling and freezing/thawing, respectively. Spin labeling studies showed a 15% faster rotational diffusion (mobility) of sulfhydryl containing proteins in the membrane of frozen/thawed spermatozoa as compared to that of fresh spermatozoa. Addition of glutathione, reduced (GSH) or oxidized (GSSG), to the cryoprotectant partially prevented the effects of freezing/thawing, such as higher exposure of sulfhydryl groups, changes in the cellular distribution, and enhanced rotational diffusion of sulfhydryl containing proteins of sperm membrane. Addition of GSSG to the cryoprotectant reduced by 35% the loss of motility of spermatozoa undergoing a freezing/thawing cycle. We concluded that cryopreservation perturbs sperm membrane sulfhydryl containing proteins and that these modifications could be partially prevented by the addition of GSSG to the cryopreservation medium. Mol. Reprod. Dev. 60: 498–506, 2001. © 2001 Wiley‐Liss, Inc.
Direct injection of foreign DNA into mouse testis as a possible in vivo gene transfer system via epididymal spermatozoa
Authors: Sato Masahiro , Ishikawa Aki , Kimura Minoru
Published: August 2002

We have attempted to transfect testicular spermatozoa with plasmid DNA by direct injection into testes to obtain transgenic animals [this technique was thus termed “testis‐mediated gene transfer (TMGT)”]. When injected males were mated with superovulated females 2 and 3 days after injection, (i) high efficiencies (more than 50%) of gene transmission were achieved in the mid‐gestational F0 fetuses, (ii) the copy number of plasmid DNA in the fetuses was estimated to be less than 1 copy per diploid cell, and (iii) overt gene expression was not found in these fetuses. These findings suggest the possibility that plasmid DNA introduced into a testis is rapidly transported to the epididymis and then incorporated by epididymal spermatozoa. The purpose of this study was to elucidate the mechanism of TMGT by introducing trypan blue (TB) or Hoechst 33342 directly into testis. We found that TB is transported to the ducts of the caput epididymis via rete testis within 1 min after testis injection, and TB reached the corpus and cauda epididymis within 2–4 days after injection. Staining of spermatozoa isolated from any portion of epididymis was observed 4 days after injection of a solution containing Hoechst 33342. Injection of enhanced green fluorescent protein (EGFP) expression vector/liposome complex into testis resulted in transfection of epithelial cells of epididymal ducts facing the lumen, although the transfection efficiency appeared to be low. In vivo electroporation toward the caput epididymis immediately after injection of EGFP expression vector into a testis greatly improved the uptake of foreign DNA by the epididymal epithelial cells. PCR analysis using spermatozoa isolated from corpus and cauda epididymis 4 days after injection of a DNA/liposome complex into testis revealed exogenous DNA in these spermatozoa even after treatment with DNase I. These findings indicate that exogenous DNA introduced into tesits is rapidly transported to epididymal ducts via the rete testis and efferent ducts, and then incorporated by epithelial cells of epididymis and epididymal spermatozoa. Mol. Reprod. Dev. 61: 49–56, 2002. © 2002 Wiley‐Liss, Inc.
Identification of the major tyrosine phosphorylated protein of capacitated hamster spermatozoa as a homologue of mammalian sperm a kinase anchoring protein
Authors: Jha Kula Nand , Shivaji S.
Published: August 2002

The molecular basis of mammalian sperm capacitation is unique in that, it is associated with a protein kinase A (PKA) dependent upregulation of protein tyrosine phosphorylation. Therefore, PKA activity during capacitation would be crucial for the downstream events of protein tyrosine phosphorylation, and mechanisms may exist to ensure that PKA phosphorylates its specific substrate. This could be achieved by bringing PKA close to its substrate, a function normally carried out by an A‐kinase anchoring protein (AKAP). We showed previously that cauda epididymidal spermatozoa of hamster undergo a capacitation‐dependent increase in protein tyrosine phosphorylation. In the present study, evidence is provided that two major tyrosine phosphorylated proteins of molecular weight 97 and 83 kDa are the hamster homologues of mouse pro‐AKAP82 and AKAP82, and have been designated as hamster pro‐AKAP83 and AKAP83 respectively. Hamster AKAP83 resembled the mouse AKAP82 with respect to its molecular weight, pI (pH 5–5.5) and cDNA and amino acid sequences. Sequence analysis indicated that the primary structure of pro‐AKAP83 was highly conserved and exhibited 91% identity with mouse and rat AKAP82. Further, the functional domains, namely the region involved in binding the regulatory subunit of PKA and the proteolytic cleavage site between pro‐AKAP83 and AKAP83, were identical with that observed in rat and mouse pro‐AKAP82 and AKAP82. Immunoblot analysis using polyclonal hamster anti‐AKAP83 antibodies indicated that AKAP83 was present both in caput and cauda epididymidal spermatozoa. The antibody also identified the pro‐AKAP82 and AKAP82 in mouse caput and cauda epididymidal spermatozoa. Immunofluorescence studies indicated that AKAP83 in hamster spermatozoa was localized along the length of principal piece of the tail. It was also demonstrated that hamster pro‐AKAP83/AKAP83 gene expression was testis specific and was not expressed in other organs in either sex. This is the first report implicating AKAP in capacitation in rodents. Mol. Reprod. Dev. 61: 258–270, 2002. © 2002 Wiley‐Liss, Inc.
Planar strip array (PSA) for MRI
Authors: Lee Ray F. , Westgate Charles R. , Weiss Robert G. , Newman David C. , Bottomley Paul A.
Published: August 2002

Parallel, spatial‐encoded MRI requires a large number of independent detectors that simultaneously acquire signals. The loop structure and mutual coupling in conventional phased arrays limit the number of coils and therefore the potential reduction in minimum scan time achievable by parallel MRI tchniques. A new near‐field MRI detector array, the planar strip array (PSA), is presented that eliminates the coupling problems and can be extended to a very large number of detectors and high MRI frequencies. Its basic structure is an array of parallel microstrips with a high permittivity substrate and overlay. The electromagnetic (EM) wavelength can be adjusted with the permittivity, and the strip lengths tuned to a preselected fraction of the wavelength of the MRI frequency. EM wave analysis and measurements on a prototype four‐element PSA reveal that the coupling between the strips vanishes when the strip length is either an integer times a quarter wavelength for a standing‐wave PSA, or a half wavelength for a travelling‐wave PSA, independent of the spacing between the strips. The analysis, as well as phantom and human MRI experiments performed by conventional and parallel‐encoded MRI with the PSA at 1.5 T, show that the decoupled strips produce a relatively high‐quality factor and signal‐to‐noise ratio, provided that the strips are properly terminated, tuned, and matched or coupled to the preamplifiers. Magn Reson Med 45:673–683, 2001. © 2001 Wiley‐Liss, Inc.
Perfusion imaging using dynamic arterial spin labeling (DASL)†
Authors: Barbier Emmanuel L. , Silva Afonso C. , Kim Seong‐Gi , Koretsky Alan P.
Published: August 2002

Recently, a technique based on arterial spin labeling, called dynamic arterial spin labeling (DASL (Magn Reson Med 1999;41:299–308)), has been introduced to measure simultaneously the transit time of the labeled blood from the labeling plane to the exchange site, the longitudinal relaxation time of the tissue, and the perfusion of the tissue. This technique relies on the measurement of the tissue magnetization response to a time varying labeling function. The analysis of the characteristics of the tissue magnetization response (transit time, filling time constant, and perfusion) allows for quantification of the tissue perfusion and for transit time map computations. In the present work, the DASL scheme is used in conjuction with echo planar imaging at 4.7 T to produce brain maps of perfusion and transit time in the anesthetized rat, under graded hypercapnia. The data obtained show the variation of perfusion and transit time as a function of arterial pCO2. Based on the data, CO2 reactivity maps are computed. Magn Reson Med 45:1021–1029, 2001. Published 2001 Wiley‐Liss, Inc.
Analysis of volume MRI and MR spectroscopic imaging data for the evaluation of patients with brain tumors
Authors: Nelson Sarah J.
Published: August 2002

The combination of volumetric MRI and multivoxel localized MR spectroscopic imaging (MRSI) data provides the potential for quantifying variations in tissue morphology and function. These techniques have numerous applications for the evaluation of neurological diseases. While state‐of‐the‐art whole‐body MR scanners are able to acquire both types of data, there have been relatively few reports which have presented clinical applications of the technology. One of the reasons for this has been the need to develop software for reconstruction and reliable interpretation of 3D imaging and spectral data. In this article, we describe the strategy developed for quantitative analysis of combined MRI and MRSI examinations from patients with brain tumors and evaluate the key components of this procedure using both simulations and empirical data from phantoms, normal volunteers, and patients. Important factors are the use of volume or interleaved multislice anatomic images as a reference, the reconstruction and correction of the spectral data for frequency, phase, and baseline distortions and consideration of the characteristics of the coil, RF pulses used for spatial selection, and phase encoding procedures. These studies show that the metabolic parameters most critical for distinguishing tumor from normal and necrotic tissue were relative levels of choline and NAA. Levels of creatine and lactate were found to be variable, both in terms of their spatial distribution within individual lesions and between different patients. Magn Reson Med 46:228–239, 2001. © 2001 Wiley‐Liss, Inc.
On the theoretical basis of perfusion measurements by dynamic susceptibility contrast MRI
Authors: Kiselev V.G.
Published: August 2002

A quantitative analysis was undertaken to calibrate the perfusion quantification technique based on tracking the first pass of a bolus of a blood pool contrast agent. A complete simulation of the bolus passage, of the associated changes in the T2 and T signals, and of the data processing was performed using the tracer dilution theory, an analytical theory of the MR signal from living tissues and numerical simulations. The noise was excluded in the simulation in order to analyze the ultimate accuracy of the method. It is demonstrated that the relationship between the contrast agent concentration and the associated changes in the transverse relaxation rate shows essentially different forms in studied tissue and in the reference artery. This effect results in systematic deviations of the measured blood flow, blood volume, and the residue function obtained with conventional processing from their true values. The error depends on the microvascular composition, the properties of the contrast agent, and the weights of the various compartments in the total signal. The results show that dynamic susceptibility contrast MRI can reach the goal of absolute perfusion quantification only with additional input from measurements of the microvascular architecture. Alternatively, the method can be used to provide such information if the perfusion is quantified by another modality. Magn Reson Med 46:1113–1122, 2001. © 2001 Wiley‐Liss, Inc.
Myotonic dystrophy type 1 (DM1) presenting with laryngeal stridor and vocal fold paresis
Authors: Ahmadian Jennifer L. , Heller Scott L. , Nishida Takashi , Altman Kenneth W.
Published: August 2002

Myotonic dystrophy type 1 (DM1) is the most common inherited muscle disorder and may present in numerous ways due to characteristic multisystem involvement. We report a 47‐year‐old man who presented with an 8‐year history of slowly progressive dyspnea and episodic stridor. The laryngeal paresis was documented with videostroboscopy and laryngeal electromyography, and treated with tracheostomy and antimyotonia agents. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
The spread of transgene expression at the site of gene construct injection
Authors: O'Hara Amanda J. , Howell John McC , Taplin Ross H. , Fletcher Sue , Lloyd Frances , Kakulas Byron , Lochmüller Hanns , Karpati George
Published: August 2002

Seven 2‐day‐old golden retriever pups were given focal intramuscular injections of a first generation adenovirus–dystrophin minigene construct and adenovirus–β‐galactosidase construct as a 2:1 mixture into the left anterior tibial muscle. The spread of transgene expression within the anterior tibial muscle was compared with the spread of methylene blue dye after identical injection into the contralateral muscle. Transgene expression 5–7 days after intramuscular injection was shown to extend between 5.8 and 11.6 mm along the biopsied muscle length (range of biopsy lengths 11.1–12.2 mm). The level of transgene expression at 2–2.5‐mm intervals from the site of injection was significantly related to the distance from the site of injection (dystrophin, P = 0.009; β‐galactosidase, P = 0.015). The spread of methylene blue dye within the anterior tibial muscle ≤24 h after identical intramuscular injection demonstrated a similar pattern to the transgene expression, with dye staining measured between 5.5 and 8.5 mm along the muscle sample length (range of biopsy lengths 5.6–15.6 mm). The greatest transgene expression and dye staining was measured 2–2.5 mm proximal to the site of injection with a maximum of 23% of muscle fibers expressing the dystrophin transgene, 95.2% expressing the β‐galactosidase transgene, and 98% of the tissue section stained with methylene blue dye. These results suggest transgene expression after focal intramuscular injection is relatively localized around the site of injection. Further research is required to develop techniques that will provide transgene expression throughout the length and breadth of a muscle. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 488–495, 2001.
Variation in motor threshold with frequency using kHz frequency alternating current
Authors: Ward Alex R. , Robertson Valma J.
Published: August 2002

We investigated the frequency dependence of motor thresholds over the frequency range 1 kHz to 25 kHz. Alternating current (AC), ramped in intensity, was applied transcutaneously, and the induced wrist extensor torque was measured. Plots of log torque versus stimulus voltage were used to accurately determine thresholds. Three kinds of sinusoidal AC stimuli were compared: continuous, 10 ms bursts at 50 Hz, and 50‐Hz single‐cycle. Differences were attributed to summation of subthreshold depolarizations. The variation in relative thresholds (continuous/single‐cycle and burst/single‐cycle) indicates that summation occurs more efficiently at higher kHz frequencies. The observed frequency and waveform dependence provides evidence for high‐frequency nerve fiber firing rates and fiber dropout when continuous or modulated AC is used, with the effects increasing with AC frequency. The form of the motor response evoked at high frequencies has features that suggest that frequencies above 10‐kHz have little or no useful clinical role in rehabilitation procedures. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1303–1311, 2001
Obstetric lesions of the brachial plexus
Authors: van Dijk J. Gert , Pondaag Willem , Malessy Martijn J. A.
Published: August 2002

The few studies on prognosis of obstetric lesions of the brachial plexus that are not hampered by selection bias or a short follow‐up suggest that functional impairment persists in 20–25% of cases, more than commonly thought. Electromyography (EMG), potentially useful for prognosis, is often considered of little value. Denervation in the first week of life has been interpreted as evidence of an antenatal lesion, but is the logical result of the short axonal length affected. EMG performed at close to the time of possible intervention (3 months) usually shows a discrepancy: motor unit potentials are seen in clinically paralyzed muscles. This can be explained in five ways: an overly pessimistic clinical examination; overestimation of EMG recruitment due to small muscle fibers; persistent fetal innervation; developmental apraxia; or misdirection, in which axons reach inappropriate muscles. Further research into the pathophysiology of obstetric lesions of the brachial plexus is needed to improve prognostication. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1451–1461, 2001
Inhibition of dynamic thigh muscle contraction by electrical stimulation of the posterior cruciate ligament in humans
Authors: Fischer‐Rasmussen Torsten , Krogsgaard Michael , Jensen Dennis Bo , Dyhre‐Poulsen Poul
Published: August 2002

We investigated the influence of electrical stimulation of the posterior cruciate ligament (PCL) on the motoneuron pool of the thigh muscle during voluntary static and dynamic muscle contraction. The study group comprised nine young men with no history of injury to the knee joints. Multistranded Teflon‐insulated stainless‐steel wires were inserted into the PCL guided by ultrasound. In three subjects wires were also inserted into the fat pad of the knee. The PCL was electrically stimulated during static, concentric, or eccentric muscle contraction with a constant load of 20% of the maximal voluntary contraction of either the quadriceps or the hamstrings. Electromyographic signals were recorded with bipolar surface electrodes placed over the vastus medialis, rectus femoris, vastus lateralis, biceps femoris caput longum, and semitendinosus muscles. The stimuli consisted of four pulses delivered at 200 HZ; the stimulus amplitude was two to three times the sensory threshold. The electrical stimulation of the PCL inhibited the ongoing muscle activity in both the quadriceps and hamstrings with latencies of 114–150 ms and 99–130 ms, respectively. Stimulation of the fat pad of the knee did not influence the muscle activity. The study suggests that the mechanoreceptors in the PCL are involved in controlling muscle activity during both static and active muscle contractions. The relative long latency of the reflex makes it unlikely that it can serve as a directly protective reflex for the cruciate ligaments. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1482–1488, 2001
Scaling of geological discontinuity normal load–deformation response using fractal geometry
Authors: Plesha Michael E. , Ni Demai
Published: August 2002

The mechanical behaviour of discontinuities in rock, such as joints, is known to be size‐dependent. It is also suspected that the behaviour of larger size features, such as faults, is also size‐dependent. This size dependence has serious implications for performing numerical response simulations of geological media. In this paper, we develop a new mathematical theory for scaling of one particular discontinuity property, namely the interface normal stiffness. To accomplish this, we idealize an interface to have fractal geometry, and we develop analytical relations which show that the interface normal stiffness, which is commonly thought to be a size‐independent property, is in fact a size‐dependent property and has fractal characteristics that may be exploited to develop a fundamental theory for scaling. Copyright © 2001 John Wiley & Sons, Ltd.
A fractal comminution approach to evaluate the drilling energy dissipation
Authors: Carpinteri Alberto , Pugno Nicola
Published: August 2002

The drilling comminution is theoretically and experimentally analysed by a fractal approach. An extension of the Third Comminution Theory is developed to evaluate the energy dissipation in the process: it occurs in a fractal domain intermediate between a surface and a volume. The theoretical assumption of a material ‘quantum’ is experimentally observed. The experimental fragment analysis evidences the characteristic size of separation between primary cutting and secondary milling. A global power balance for the drilling process is also presented and permits the prediction of drilling velocity. It shows also how the dissipation energy density (drilling strength) is not a constant parameter, but decreases considerably with the size scale. Copyright © 2002 John Wiley & Sons, Ltd.
Optimal switchover times between two activities utilizing the same resource
Authors: Karakul M. , Parlar M.
Published: August 2002

The “gold‐mining” decision problem is concerned with the efficient utilization of a delicate mining equipment working in a number of different mines. Richard Bellman was the first to consider this type of a problem. The solution found by Bellman for the finite‐horizon, continuous‐time version of the problem with two mines is not overly realistic since he assumed that fractional parts of the same mining equipment could be used in different mines and this fraction could change instantaneously. In this paper, we provide some extensions to this model in order to produce more operational and realistic solutions. Our first model is concerned with developing an operational policy where the equipment may be switched from one mine to the other at most once during a finite horizon. In the next extension we incorporate a cost component in the objective function and assume that the horizon length is not fixed but it is the second decision variable. Structural properties of the optimal solutions are obtained using nonlinear programming. Each model and its solution is illustrated with a numerical example. The models developed here may have potential applications in other areas including production of items requiring the same machine or choosing a sequence of activities requiring the same resource. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 186–203, 2002; DOI 10.1002/nav.10008
Dynamic pricing and inventory control with learning
Authors: Petruzzi Nicholas C. , Dada Maqbool
Published: August 2002

Optimal operating policies and corresponding managerial insight are developed for the decision problem of coordinating supply and demand when (i) both supply and demand can be influenced by the decision maker and (ii) learning is pursued. In particular, we determine optimal stocking and pricing policies over time when a given market parameter of the demand process, though fixed, initially is unknown. Because of the initially unknown market parameter, the decision maker begins the problem horizon with a subjective probability distribution associated with demand. Learning occurs as the firm monitors the market's response to its decisions and then updates its characterization of the demand function. Of primary interest is the effect of censored data since a firm's observations often are restricted to sales. We find that the first‐period optimal selling price increases with the length of the problem horizon. However, for a given problem horizon, prices can rise or fall over time, depending on how the scale parameter influences demand. Further results include the characterization of the optimal stocking quantity decision and a computationally viable algorithm. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 303–325, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10013
On the use of second‐order descriptors to predict queueing behavior of MAPs
Authors: Andersen Allan T. , Nielsen Bo Friis
Published: August 2002

The contributions of this paper are the following: We derive a formula for the IDI (Index of Dispersion for Intervals) for the Markovian Arrival Process (MAP). We show that two‐state MAPs with identical fundamental rate, IDI and IDC (Index of Dispersion for Counts), define interval stationary point processes that are stochastically equivalent; this is true for the time stationary point processes they define too. Special cases of the two‐state MAP are frequently used as source models in the literature. The result shows that, fitting to the rate, IDC and IDI of a source completely determine the interval stationary and time stationary behavior of the two‐state model. We give various illustrative numerical examples on the merits in predicting queueing behavior on the basis of first‐ and second‐order descriptors by considering queueing behavior of MAPs with constant fundamental rate and IDC, respectively, constant fundamental rate and IDI. Disturbing results are presented on how different the queueing behavior can be with these descriptors fixed. Even MAPs with NO correlations in the counting process, i.e., IDC(t) = 1 are shown to have very different queueing behavior. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 391–409, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10015
Rendezvous search when marks are left at the starting points
Authors: Baston Vic , Gal Shmuel
Published: August 2002

Leaving marks at the starting points in a rendezvous search problem may provide the players with important information. Many of the standard rendezvous search problems are investigated under this new framework which we call markstart rendezvous search. Somewhat surprisingly, the relative difficulties of analysing problems in the two scenarios differ from problem to problem. Symmetric rendezvous on the line seems to be more tractable in the new setting whereas asymmetric rendezvous on the line when the initial distance is chosen by means of a convex distribution appears easier to analyse in the original setting. Results are also obtained for markstart rendezvous on complete graphs and on the line when the players' initial distance is given by an unknown probability distribution. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 722–731, 2001
Stochastic allocation of inspection capacity to competitive processes
Authors: Jang Wooseung , Shanthikumar J. George
Published: August 2002

Optimal allocation and control of limited inspection capacity for multiple production processes are considered. The production processes, which operate independently but share inspection capacity, are subject to random failures and are partially observed through inspection. This study proposes an approach of stochastic allocation, using a Markov decision process, to minimize expected total discounted cost over an infinite time horizon. Both an optimal model and a disaggregate approximation model are introduced. The study provides some structural results and establishes that the control policy is of a threshold type. Numerical experiments demonstrate a significantly decreased amount of computational time required for the disaggregate approach when compared to the optimal solution, while generating very good control policies. © 2002 John Wiley & Sons, Inc. Naval Research Logistics, 49: 78–94, 2002; DOI 10.1002/nav.1049
High‐resolution imaging demonstrates dynein‐based vesicular transport of activated trk receptors
Authors: Bhattacharyya Anita , Watson Fiona L. , Pomeroy Scott L. , Zhang Yanzhen Z. , Stiles Charles D. , Segal Rosalind A.
Published: August 2002

Target‐derived neurotrophins signal from nerve endings to the cell body to influence cellular and nuclear responses. The retrograde signal is conveyed by neurotrophin receptors (Trks) themselves. To accomplish this, activated Trks may physically relocalize from nerve endings to the cell bodies. However, alternative signaling mechanisms may also be used. To identify the vehicle wherein the activated Trks are located and transported, and to identify associated motor proteins that would facilitate transport, we use activation‐state specific antibodies in concert with immunoelectron microscopy and deconvolution microscopy. We show that the activated Trks within rat sciatic nerve axons are preferentially localized to coated and uncoated vesicles. These vesicles are moving in a retrograde direction and so accumulate distal to a ligation site. The P‐Trk containing vesicles, in turn, colocalize with dynein components, and not with kinesins. Collectively, these results indicate activated Trk within axons travel in vesicles and dynein is the motor that drives these vesicles towards the cell bodies. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 302–312, 2002
Expression and function of Xenopus laevis p75NTR suggest evolution of developmental regulatory mechanisms
Authors: Hutson Lara D. , Bothwell Mark
Published: August 2002

Neurotrophins signal through two different classes of receptors, members of the trk family of receptor tyrosine kinases, and p75 neurotrophin receptor (p75NTR), a member of the tumor necrosis factor receptor family. While neurotrophin binding to trks results in, among other things, increased cell survival, p75NTR has enigmatically been implicated in promoting both survival and cell death. Which of these two signals p75NTR imparts depends on the specific cellular context. Xenopus laevis is an excellent system in which to study p75NTR function in vivo because of its amenability to experimental manipulation. We therefore cloned partial cDNAs of two p75NTR genes from Xenopus, which we have termed p75NTRa and p75NTRb. We then cloned two different cDNAs, both of which encompass the full coding region of p75NTRa. Early in development both p75NTRa and p75NTRb are expressed in developing cranial ganglia and presumptive spinal sensory neurons, similar to what is observed in other species. Later, p75NTRa expression largely continues to parallel p75NTR expression in other species. However, Xenopus p75NTRa is additionally expressed in the neuroepithelium of the anterior telencephalon, all layers of the retina including the photoreceptor layer, and functioning axial skeletal muscle. Finally, misexpression of full length p75NTR and each of two truncated mutants in developing retina reveal that p75NTR probably signals for cell survival in this system. This result contrasts with the reported role of p75NTR in developing retinae of other species, and the possible implications of this difference are discussed. © 2001 John Wiley & Sons, Inc. J Neurobiol 49: 79–98, 2001
Stable factorization for Hankel and Hankel‐like matrices
Authors: Olshevsky Vadim , Stewart Michael
Published: August 2002

This paper gives fast O(n2) algorithms for the factorization of positive‐definite and indefinite Hankel matrices. The algorithms are based on the concept of displacement structure and are valid for the more general class of Hankel‐like matrices. The positive‐definite algorithm is proven to be backward stable. The indefinite algorithm uses a look‐ahead step that is naturally suggested by displacement approach. Our error analysis suggests a new criterion for the size of the look‐ahead step and our numerical experiments suggest that the use of the new criterion allows us to ensure numerical stability in practice. Copyright © 2001 John Wiley & Sons, Ltd.
Initial strain formulation without internal cells for elastoplastic analysis by triple‐reciprocity BEM
Authors: Ochiai Yoshihiro , Kobayashi Tadashi
Published: August 2002

In general, internal cells are required to solve elastoplasticity problems using a conventional boundary element method (BEM). However, in this case, the merit of BEM, which is the easy method of preparation of data, is lost. The conventional multiple‐reciprocity boundary element method (MRBEM) cannot be used to solve the elastoplasticity problems because the distribution of initial strain or initial stress cannot be determined analytically. In this paper, we show that two‐dimensional elastoplasticity problems can be solved without the use of internal cells, by using the triple‐reciprocity boundary element method. An initial strain formulation is adopted and the initial strain distribution is interpolated using boundary integral equations. A new computer programme was developed and applied to several problems. Copyright © 2001 John Wiley & Sons, Ltd.
The efficiency of the p‐version finite element method in a distributed computing environment
Authors: Rank Ernst , Rücker Martin , Düster Alexander , Bröker Henrike
Published: August 2002

The p‐version of the finite element method is now commonly considered to be a very accurate discretization method for linear elliptic partial differential equations, but many researchers still doubt the efficiency of this method, when compared to the classical h‐version and applied to more complex problems. This paper will first discuss some general considerations about the efficiency of a numerical method and then present results on an evaluation of the p‐version. It will be shown, that there are many special techniques being applicable to the p‐version, yielding a well‐performing and robust method. This will be demonstrated on several examples, including non‐linear problems and a parallel implementation on a workstation cluster. A client–server software structure for an efficient integration of CAD and FEA using a strict separation of geometric and non‐geometric aspects will also be outlined. Copyright © 2001 John Wiley & Sons, Ltd.
FETI‐DP: a dual–primal unified FETI method—part I: A faster alternative to the two‐level FETI method
Authors: Farhat Charbel , Lesoinne Michel , LeTallec Patrick , Pierson Kendall , Rixen Daniel
Published: August 2002

The FETI method and its two‐level extension (FETI‐2) are two numerically scalable domain decomposition methods with Lagrange multipliers for the iterative solution of second‐order solid mechanics and fourth‐order beam, plate and shell structural problems, respectively.The FETI‐2 method distinguishes itself from the basic or one‐level FETI method by a second set of Lagrange multipliers that are introduced at the subdomain cross‐points to enforce at each iteration the exact continuity of a subset of the displacement field at these specific locations. In this paper, we present a dual–primal formulation of the FETI‐2 concept that eliminates the need for that second set of Lagrange multipliers, and unifies all previously developed one‐level and two‐level FETI algorithms into a single dual–primal FETI‐DP method. We show that this new FETI‐DP method is numerically scalable for both second‐order and fourth‐order problems. We also show that it is more robust and more computationally efficient than existing FETI solvers, particularly when the number of subdomains and/or processors is very large. Copyright © 2001 John Wiley & Sons, Ltd.
Automatic generation of transitional meshes
Authors: Field David A.
Published: August 2002

Advances in commercial computer‐aided design software have made finite element analysis with three‐dimensional solid finite elements routinely available. Since these analyses usually confine themselves to those geometrical objects for which particular CAD systems can produce finite element meshes, expanding the capability of analyses becomes an issue of expanding the capability of generating meshes. This paper presents a method for stitching together two three‐dimensional meshes with diverse elements that can include tetrahedral, pentahedral and hexahedral solid finite elements. The stitching produces a mesh that coincides with the edges which already exist on the portion of boundaries that will be joined. Moreover, the transitional mesh does not introduce new edges on these boundaries. Since the boundaries of the regions to be stitched together can have a mixture of triangles and quadrilaterals, tetrahedral and pyramidal elements provide the transitional elements required to honor these constraints. On these boundaries a pyramidal element shares its base face with the quadrilateral faces of hexahedra and pentahedra. Tetrahedral elements share a face with the triangles on the boundary. Tetrahedra populate the remaining interior of the transitional region. Copyright © 2001 John Wiley & Sons, Ltd.
Fast direct solvers for Poisson equation on 2D polar and spherical geometries
Authors: Lai Ming‐Chih , Wang Wei‐Cheng
Published: August 2002

A simple and efficient class of FFT‐based fast direct solvers for Poisson equation on 2D polar and spherical geometries is presented. These solvers rely on the truncated Fourier series expansion, where the differential equations of the Fourier coefficients are solved by the second‐ and fourth‐order finite difference discretizations. Using a grid by shifting half mesh away from the origin/poles, and incorporating with the symmetry constraint of Fourier coefficients, the coordinate singularities can be easily handled without pole condition. By manipulating the radial mesh width, three different boundary conditions for polar geometry including Dirichlet, Neumann, and Robin conditions can be treated equally well. The new method only needs O(MN log2 N) arithmetic operations for M × N grid points. © 2002 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 18: 56–68, 2002
Hemodialysis patient beliefs by stage of fluid adherence
Authors: Welch Janet L.
Published: August 2002

Fluid limitations are difficult for hemodialysis patients to follow, and factors related to fluid adherence are not well known. The primary purpose of this study, which was guided by the health belief model and the transtheoretical model for behavior change, was to determine whether differences exist in perceived benefits, barriers, susceptibility, seriousness, or self‐efficacy among individuals in different stages of fluid adherence. In a cross‐sectional descriptive design, 148 persons (mean age=53.9 years; 52% male) were interviewed using a structured format. Hemodialysis patients in the action/maintenance stage perceived significantly more benefits to fluid adherence than persons in the precontemplation stage. Persons who were in the action/maintenance stage perceived they were significantly more susceptible to pulmonary edema than persons in the contemplation stage. Stage‐appropriate interventions may be needed to target specific beliefsabout fluid adherence. © 2001 John Wiley & Sons, Inc. Res Nurs Health 24: 105–112, 2001
Archaeozoological evidence for pastoral systems and herd mobility: the remains from Sos Höyük and Büyüktepe Höyük
Authors: Howell‐Meurs Sarah
Published: August 2002

Characterization of pastoral economics in the archaeological record is recognized as being particularly difficult. While architectural evidence may provide ambiguous indicators of nomadism, animal remains afford greater clarity concerning assessment of herd and thus economic mobility. To highlight archaeozoological applications towards the analysis of herd movement as it may relate to the analysis and definition of economic systems, the mobility of the pastoral systems practised at Sos Höyük and Büyüktepe Höyük during the Early Bronze and Iron Age periods was investigated in terms of various facets of archaeozoological evidence. Sedentary occupation of these sites was suggested by the faunal remains on the basis of evidence, including use of seasonally available resources, relative abundance and representation of the main domesticates and dental data. These results suggest that analysis based upon multiple lines of archaeozoological evidence provides the most fruitful means of investigating pastoral mobility. Copyright © 2001 John Wiley & Sons, Ltd.
Two decapitations from Roman Towcester
Authors: Anderson T.
Published: August 2002

Two young adult males from a Roman cemetery at Towcester show unambiguous evidence of decapitation In one, the skull had been placed over the lower legs, and in the other, the skull was in its correct anatomical position. The significance of this variation and the reasons for decapitation are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Challenges to African Governance and Civil Society
Authors: Mule Harris
Published: August 2002

The theme of this symposium, 1

Papers in the symposium were presented for the conference on African Governance and Civil Society: Equity, Efficiency and Participation, Cornell University, 10–11 March 2000, held in honour of John Cohen.

African Governance and Civil Society, is fitting. John Cohen spent the better part of his working life in furthering better governance in Africa through economic development. More than 20 years ago as Chief Economist in the Kenyan government, I was introduced to John Cohen through another John, John Thomas, who was then the head of the HIID (Harvard Institute for International Development) advisory team in Kenya. He brought to me the CV of John Cohen, and it was extraordinary. Here was a CV of someone with a doctorate in jurisprudence and a Ph.D. in Political Science. Obviously I was impressed, but I was also perplexed. Twenty years ago most of us, if not all of us, thought about development in purely economic terms. We thought development was about economics. I told Dr Thomas, ‘You are bringing this CV of someone who's very intelligent, but he is a lawyer and political scientist, and we are talking about economic development.’ In response, he told me a story about John Cohen. He said, ‘This man whose CV you are looking at is a lawyer. As an attorney in the US he can make a lot of money. John Cohen, however, has a vision that transcends money. He wants to serve humanity and the public. It is for that reason that he went back to college and got a degree in political science.’ I found that remarkable.

Development is more than techniques. Development is about people, humanity, vision, optimism and hope. Anybody with vision, optimism and hope for humanity can make a good development planner. I was persuaded that John Cohen was the right person to hire as an adviser in the Ministry of Agriculture for the development of Kenya. I think that was one of the best decisions I ever made as Chief Economist. Over the years, between the late 1970s and late 1980s, John served Kenya well. In terms of advice for agricultural and rural development, he and David Lewis introduced in Kenya the strategy of District Focus for Rural Development that laid the cornerstone for our rural development programmes. This strategy was 10 or 15 years ahead of its time. Everyone in Africa is now talking about decentralization, about empowering the rural population to take care of its development. Copyright © 2001 John Wiley & Sons, Ltd.
Business associations and better governance in Africa
Authors: Goldsmith Arthur A.
Published: August 2002

Are business associations a cure for or a cause of bad governance in Africa? Pluralists think business associations are needed to bargain and compromise over improvements in public policy, whereas public choice theorists suspect business associations of destructive rent‐seeking. This article reports results of a survey in eight African countries that illuminates these issues. Most business leaders and civil servant respondents see major problems with governance, though across countries there is a perception of improvement. Business associations are reported to work reasonably well as policy advocates for better governance. They are seen as doing a fair job of keeping members updated on the policy environment. The associations also appear to be building ‘social capital’ (the ability to trust and work cooperatively with others) among member firms. Thus, the evidence is that business associations in Africa conform better to the pluralist model of interest group behaviour, as opposed to the more critical public choice viewpoint. Copyright © 2002 John Wiley & Sons, Ltd.
Plasma polymerization and deposition of glycidyl methacrylate on Si(100) surface for adhesion improvement with polyimide
Authors: Zou X. P. , Kang E. T. , Neoh K. G. , Zhang Y. , Tan K. L. , Cui C. Q. , Lim T. B.
Published: August 2002

Thin polymer films were deposited on Si(100) surfaces by plasma polymerization of glycidyl methacrylate (GMA) under different glow discharge conditions. The FT‐IR, X‐ray photoelectron spectroscopy (XPS), and amine treatment results suggested that the epoxide functional groups of the deposited films had been preserved to various extents, depending on the plasma deposition conditions. The use of a low radio frequency power (∼ 5 W) and a relatively high system pressure (100–400 Pa) readily resulted in the deposition of thin films having nearly the same composition of the epoxide functional groups as that of the GMA homopolymer. The plasma‐polymerized GMA (PP‐GMA) thin films deposited on the Ar plasma‐pretreated Si(100) surfaces were retained to a large extent after acetone extraction, suggesting the presence of covalent bonding between the PP‐GMA layer and the Si surface. Thermal imidization of the poly(amic acid) precursor of polyimide on the GMA plasma‐polymerized Si(100) surface resulted in a strongly adhered polyimide film. The adhesion results further suggested that the GMA polymer had been grafted on the Si(100) surface and the epoxide functional groups had undergone reactive interaction (curing) with the carboxylic and amine groups of the poly(amic acid) during thermal imidization. Copyright © 2001 John Wiley & Sons, Ltd.
Application of photopolymer to core‐hair type microgels with various hair length
Authors: Takahashi Takanori , Watanabe Hiroomi , Miyagawa Nobukazu , Takahara Shigeru , Yamaoka Tsuguo
Published: August 2002

The new microgels, called “core‐hair” type microgels, were synthesized. They have a hair moiety consisting of the oxyhexano‐1,7‐diyl (O(CH2)5C(O)) group as a spacer and the acryloyl group for polymerization. The hair length depends on the number of spacer units, and affects the viscosity and the thixotropy index of the microgel. These core‐hair microgels show the pseudo‐plastic flow of a non‐Newtonian fluid with moderate to high dispersibility in water or alcoholic solvents. Due ­to their viscosities and dispersibilities, these core‐hair microgels are useful for photopolymer, e.g. for screen printing. Therefore, these microgels were actually applied to screen printing and confirmed pattern forming on a screen printing plate through water development. We now discuss the relation between the viscosity, the dispersibility, the photosensitivity, and the rate of photopolymerization to the hair length of the microgel. Copyright © 2001 John Wiley & Sons, Ltd.