bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast MRI of RF heating via phase difference mapping
Authors: Shapiro Erik M. , Borthakur Arijitt , Shapiro Michael J. , Reddy Ravinder , Leigh John S.
Published: August 2002

A method is presented for the rapid acquisition of temperature maps derived from phase difference maps. The temperature‐dependent chemical shift coefficients (TDCSCs) of various concentrations of aqueous cobalt and dysprosium‐based compounds were measured. The largest TDCSC calculated was for 100 mM DyEDTA, which had a TDCSC of –0.09 PPM/K; 160 mM CoCl2 had a TDCSC of –0.04 PPM/K. These temperature‐dependent chemical shifts (TDCSs) result in phase changes in the MR signal with changing temperature. Agarose phantoms were constructed with each paramagnetic metal. A fast gradient‐echo (FGRE) MR image was acquired to serve as the baseline image. A “test” MRI procedure was then performed on the phantom. Immediately afterwards, a second FGRE MR image was acquired, serving as the probing image. Proper image processing as a phase difference map between the probing image and the baseline image resulted in an image which quantitatively described the temperature increase of the phantom in response to a particular “test” imaging experiment. Applications of this technique in assessing the safety of pulse sequences and MR coils are discussed. Magn Reson Med 47:492–498, 2002. © 2002 Wiley‐Liss, Inc.
Abdominal imaging with a modular combination of spin and gradient echoes
Authors: Jakob P.M. , Hillenbrand Claudia M. , Kenn Werner , D. Hahn  , Haase A.
Published: August 2002

MR‐CAT (combined acquisition technique), a modular hybrid imaging concept, was introduced recently. In this article it is demonstrated that the CAT principles can be applied to form a versatile combination of spin and gradient echoes for abdominal imaging. This CAT approach, which essentially integrates RARE and EPI modules in a sequential fashion, was used to implement a set of segmented and single‐shot RARE/EPI‐CAT imaging techniques. CAT was used in in vivo studies to perform high‐resolution abdominal imaging in five healthy subjects. The results demonstrate the feasibility of abdominal imaging using the proposed CAT approach and the potential of this technique to reduce imaging time while preserving image quality. Magn Reson Med 47:425–432, 2002. © 2002 Wiley‐Liss, Inc.
Proton magnetization transfer effect in rat liver lactate
Authors: Dresselaers Tom , Bergans Niki , Van Hecke Paul , Vanstapel Florent
Published: August 2002

Off‐resonance lactate magnetization transfer (MT) experiments were performed on the in situ rat liver under perfused and ischemic conditions. A significant MT effect for lactate methyl protons was observed. The effect was larger for the ischemic condition than for the perfused condition, and was largest in the blood‐filled ischemic livers. The size of the motionally restricted lactate pool, determined using a two‐pool model fit, was estimated to be about 1% in perfused livers and about 1.8–2.5% after more than 1 hr of onset of ischemia, suggesting that lactate in liver is almost fully NMR‐visible. The MT data for both the perfused and the ischemic condition appeared to be better approximated when assuming a superLorentzian lineshape for the immobile pool rather than a Gaussian lineshape. Finally, the experiments demonstrated a coupling between the lactate methyl and water protons, which may be mediated by macromolecules. Magn Reson Med 47:880–887, 2002. © 2002 Wiley‐Liss, Inc.
1H NMR visible lipids are induced by phosphonium salts and 5‐fluorouracil in human breast cancer cells
Authors: Cooper Wendy A. , Bartier Wendy A. , Rideout Darryl C. , Delikatny Edward J.
Published: August 2002

Cationic lipophilic phosphonium salts (CLPS) selectively accumulate in the mitochondria of neoplastic cells and inhibit mitochondrial function. The effects of the CLPS p‐(triphenylphosphoniummethyl) benzaldehyde chloride (drug A), and [4‐(hydrazinocarboxy)‐1‐butyl] tris‐(4‐dimethylaminophenyl) phosphonium chloride (drug B), on human breast cells of differing biological properties were assessed using growth inhibition assays and 1H NMR. Drug A and, to a lesser extent, drug B demonstrated selective growth inhibition of the highly tumorigenic DU4475 breast carcinoma cell line compared to the transformed HBL‐100 human breast cell line. However, in contrast to previous studies using other cell lines, no synergistic activity was found when the drugs were used in combination. 1H NMR demonstrated significant increases in mobile lipid acyl chain resonances in both cell lines treated with cytotoxic doses (IC50, 48 h) of the drugs used either alone or in combination. Two‐dimensional NMR revealed accompanying decreases in phosphocholine/Lys levels in HBL‐100 cells treated with A, B, or a 1:1 combination A+B at the IC50, and in DU4475 cells treated with drug A (IC50). This was accompanied by significant increases in cho/Lys ratios with IC50 A or combination A+B treatment. Similar spectra were observed in cells treated with 5‐fluorouracil but not methotrexate, indicating that mobile lipid accumulation is a general but not universal response to cytotoxic insult. Magn Reson Med 45:1001–1010, 2001. © 2001 Wiley‐Liss, Inc.
Ghost artifact cancellation using phased array processing
Authors: Kellman Peter , McVeigh Elliot R.
Published: August 2002

In this article, a method for phased array combining is formulated which may be used to cancel ghosts caused by a variety of distortion mechanisms, including space variant distortions such as local flow or off‐resonance. This method is based on a constrained optimization, which optimizes SNR subject to the constraint of nulling ghost artifacts at known locations. The resultant technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation it is applied to full field‐of‐view (FOV) images. The method is applied to multishot EPI with noninterleaved phase encode acquisition. A number of benefits, as compared to the conventional interleaved approach, are reduced distortion due to off‐resonance, in‐plane flow, and EPI delay misalignment, as well as eliminating the need for echo‐shifting. Experimental results demonstrate the cancellation for both phantom as well as cardiac imaging examples. Magn Reson Med 46:335–343, 2001. Published 2001 Wiley‐Liss, Inc.
Improving relative anisotropy measurement using directional correlation of diffusion tensors
Authors: Sun Shu‐Wei , Song Sheng‐Kwei , Hong Chung‐Yi , Chu Woei C. , Chang Chen
Published: August 2002

A method employing directional correlation of the diffusion tensor, directional‐correlation weighted relative anisotropy (DRA), was developed to improve the accuracy of estimated relative anisotropy (RA). The intravoxel directional correlation was established on the same voxel between two identically acquired diffusion tensor images, and the correlation coefficient derived from tensor dot product was employed as the weighting factor applied in the calculation of RA. The effect of noise influence was reduced since the random noise between repeated scans is not directionally correlated. The RA and the inter‐ and intravoxel DRA estimations were examined on rat brains in vivo. The background noise alters the direction of eigenvectors and the magnitude of eigenvalues. The dispersion angle between repeatedly obtained eigenvectors, representing the extent of directional alteration of eigenvectors, depends on the tissue anisotropy as well as the signal‐to‐noise ratio (SNR) of the source images. Current results demonstrate that the intravoxel DRA improves the accuracy of RA estimation, increases the relative contrast of gray and white matter, and avoids the partial volume effect commonly seen in the intervoxel operations. Magn Reson Med 46:1088–1092, 2001. © 2001 Wiley‐Liss, Inc.
A pharmacokinetic model for quantitative evaluation of spinal cord injury with dynamic contrast‐enhanced magnetic resonance imaging
Authors: Bilgen Mehmet , Narayana Ponnada A.
Published: August 2002

A multicompartment pharmacokinetic model was proposed to quantitatively describe the distribution of the contrast agent gadopentetate‐dimeglumine (Gd) in an experimental spinal cord injury (SCI). Concentration of Gd was measured in different compartments with in vivo dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) in the acute phase of injury. The concentration data for each rat was fitted to the model to estimate transfer rates between different compartments. The results indicate: 1) lack of uptake of Gd in normal cord tissue, 2) rapid exchange of Gd between plasma and cerebrospinal fluid in both normal and injured cord tissues, and 3) slower uptake of Gd in injured cord. With this approach, it is possible to quantify the integrity of the blood–spinal cord barrier (BSCB) in vivo, evaluate the pathobiology of injured cord, assess the efficacy of interventions, and monitor the progression of injury with postinjury time. Magn Reson Med 46:1099–1106, 2001. © 2001 Wiley‐Liss, Inc.
Zero‐quantum filter offering single‐shot lipid suppression and simultaneous detection of lactate, choline, and creatine resonances
Authors: Star‐Lack J.M. , Spielman D.M.
Published: August 2002

A zero‐quantum (ZQ) filter offering single‐shot lipid suppression and providing for simultaneous detection of the lactate methyl doublet (1.3 ppm) and nonoverlapping singlets including choline (Cho, 3.2 ppm) and creatine (Cr, 3.0 ppm) is described. Filtering is provided by soft mixing and reading pulses (RFmix, RFrd) that are selective for the lactate methine quartet (4.1 ppm), Cho, and Cr resonances but exclude the 1.3 ppm lactate component and overlapping lipids. Surrounding RFmix and RFrd are magnetic field gradient pulses of equal magnitude but opposite signs to enable the rephasing of the zero‐quantum lactate coherence and the creation of a stimulated echo for singlets within the pulse passbands. The sequence is designed to retain half the original lactate and singlet signal intensities. Theoretical predictions were confirmed experimentally at 1.5T using phantom acquisitions. The lipid suppression factor was measured to be over 103. Magn Reson Med 46:1233–1237, 2001. © 2001 Wiley‐Liss, Inc.
Projection reconstruction balanced fast field echo for interactive real‐time cardiac imaging
Authors: Schaeffter Tobias , Weiss Steffen , Eggers Holger , Rasche Volker
Published: August 2002

A balanced fast field echo (FFE) sequence (also referred to as true fast imaging with steady precession (true FISP)), based on projection reconstruction (PR) is evaluated in combination with real‐time reconstruction and interactive scanning capabilities for cardiac function studies. Cardiac image sequences obtained with the balanced PR‐FFE method are compared with images obtained with a spin‐warp (2D Fourier transform (2DFT)) technique. In particular, the representation of motion artifacts in both techniques is investigated. Balanced PR‐FFE provides a similar contrast to spin‐warp‐related techniques, but is less sensitive to motion artifacts. The use of angular undersampling within balanced PR‐FFE is examined as a means to increase temporal resolution while causing only minor artifacts. Furthermore, a modification of the profile order allows the reconstruction of PR images at different spatial and temporal resolution levels from the same data. This study shows that balanced PR‐FFE is a robust tool for cardiac function studies. Magn Reson Med 46:1238–1241, 2001. © 2001 Wiley‐Liss, Inc.
Reproducibility of motor unit number estimation in individual subjects
Authors: Simmons Zachary , Epstein David K. , Borg Bryson , Mauger David T. , Kothari Milind J. , Shefner Jeremy M.
Published: August 2002

Although the reproducibility of motor unit number estimation (MUNE) for groups of subjects has been studied, there is little such data for individuals. Prediction intervals represent a tool to study individual MUNE reproducibility and represent the range of values expected for a future MUNE if the true number of motor units remains unchanged. MUNE was performed using the statistical method on 48 normal individuals. The prediction interval was found to be a function of the intrasubject coefficient of variation. Using a commercial manufacturer's recommended technique and software, prediction intervals were found to be so broad as to be of uncertain value. We found that by averaging two MUNE observations for each determination, and using the method of weighted averages for calculating the size of an average single motor unit potential, the intrasubject coefficient of variation was reduced from 16.48% to 8.77%, and the 90% prediction interval became sufficiently narrow to be clinically useful. False‐negative rates were also lowered substantially using these techniques. Thus, simple modifications of an existing MUNE program improved the clinical utility of this program for the longitudinal study of patients in whom changes in motor unit number over time are of importance, such as those with motor neuron diseases. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 467–473, 2001
The susceptibility of muscle cells to oxidative stress is independent of nitric oxide synthase expression
Authors: Zhuang Weiyun , Eby Josh C. , Cheong Monica , Mohapatra Pramit K. , Bredt David S. , Disatnik Marie‐Hélène , Rando Thomas A.
Published: August 2002

The free radical, nitric oxide (NO·), has been implicated in the pathogenesis of muscular dystrophies because the enzyme, nitric oxide synthase (NOS), which produces NO·, binds to the dystrophin–glycoprotein complex (DGC). In various studies of tissue samples from human and animal muscular dystrophies due to DGC defects, correlations between reductions of NOS activity and disease severity have been reported. To test for any direct effect of NOS expression on muscle cell susceptibility, we examined muscle cells in vitro under conditions of experimentally altered NOS activity. There were no differences in susceptibility to oxidative stress between differentiated myotube cultures from wild‐type and from neuronal NOS (nNOS)‐deficient mice. Likewise, pharmacological inhibition of NOS did not alter cellular susceptibility to oxidative challenges. Overexpression of NOS neither enhanced nor diminished cellular susceptibility to oxidative stress. Finally, we assessed the effect of NOS overexpression on myotube cultures from dystrophin‐deficient (mdx) mice. NOS protein was localized to both membrane and cytosolic compartments in the transduced cells. Still, no difference in susceptibility to oxidative stress was found between the NOS‐overexpressing cells and control cells. These data suggest that muscle cell susceptibility to oxidative challenges is independent of the level of NOS expression. Therefore, any role NO· may play in the pathogenesis of muscular dystrophies is likely to be independent of its effect on the redox state of the cell. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 502–511, 2001
Prolonged median sensory latency as a predictor of future carpal tunnel syndrome
Authors: Werner Robert A. , Gell Nancy , Franzblau Alfred , Armstrong Thomas J.
Published: August 2002

The purpose of the study was to determine whether abnormal median sensory nerve conduction among asymptomatic workers was predictive of future symptoms suggestive of carpal tunnel syndrome (CTS). This was a prospective study involving 77 workers who were identified as asymptomatic cases with electrodiagnostic findings of median mononeuropathy compared to an age‐ and sex‐matched control group. Follow‐up was completed an average of 70 months later, and subjects who reported pain, numbness, tingling, or burning in the distribution of the median nerve, based upon a hand diagram, were classified as having CTS symptoms. The follow‐up participation rate was 70%. Among subjects with abnormal median sensory latencies, 23% went on to develop symptoms consistent with CTS within the follow‐up period, compared with 6% in the control group (P = .010). Age and hand repetition were also risk factors for CTS, but the majority of asymptomatic workers with a median mononeuropathy do not become symptomatic over an extended time. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1462–1467, 2001
A sequential attribute sampling inspection game for item facilities
Authors: Canty Morton , Rothenstein Daniel , Avenhaus Rudolf
Published: August 2002

The routine inspection of facilities storing large numbers of identical items is modeled as a two‐person, sequential game. Timely detection of illegal activity is parameterized in terms of a critical time to detection, and equilibria are derived which provide inspection strategies. Necessary conditions for deterrence of illegal behavior are discussed. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 496–505, 2001
Decoupling of the short‐term hemodynamic response and the blood oxygen concentration
Authors: Janz Clemens , Schmitt Christina , Kornmayer Jens , Speck Oliver , Hennig Jürgen
Published: August 2002

Neuronal activation leads to an increase in the local cortical perfusion. The exact regulatory mechanisms leading to these changes are still unknown. To elucidate the role of oxygen in the initial hemodynamic regulation, a disactivation paradigm was performed with fMRI. A stimulus was applied following a previous extended activation in order to evoke physiological variations of the local oxygen concentration. The results demonstrate that the initial hemodynamic response time is independent of the local blood oxygen concentration. Copyright © 2001 John Wiley & Sons, Ltd.

Abbrevations used:

BOLD

blood oxygenation level dependent

CBF

cerebral blood flow

CMRO2

cerebral metabolic rate of oxygen

fMRI

functional magnetic resonance imaging

FOV

field‐of‐view

GE‐EPI

gradient echo–echo planar imaging
Predicting BOLD signal changes as a function of blood volume fraction and resolution
Authors: Cheng Yu‐Chung N. , Haacke E. Mark
Published: August 2002

The appropriate choice of resolution in fMRI remains an open question. To address this issue, we simulate the signal change between activated and resting states as a function of blood volume fraction (λ). From these results, the relative contrast‐to‐noise ratio (CNR) from the resting to the activated state can be calculated as a function of resolution. We consider different vessel orientations and note that, in most cases, the most efficient scanning procedure is for low resolution imaging. To overcome this limitation, a T1 enhancing contrast agent is proposed to increase the signal from the blood and, hence, the intravascular contribution to the BOLD effect. We show that this effect dramatically increases both the signal changes and the efficiency of high‐resolution imaging and should lead to much better visualization and localization of parenchymal changes. Copyright © 2001 John Wiley & Sons, Ltd.
Improving network service quality with explicit TCP window control
Authors: Aweya James , Ouellette Michel , Montuno Delfin Y. , Yao Zhonghui
Published: August 2002

We describe in this paper a new TCP rate control scheme based on a simple recursive algorithm. The idea behind the algorithm is to match the offered network load to the available resources by modifying at an intermediate network element, the receiver's advertised window in TCP acknowledgments returning to the source. We show through simulations that the scheme can efficiently control TCP traffic to limit queue buildups and buffer requirements at the network nodes, resulting in significant improvements in delay, packet loss rates, fairness, throughput and link utilization. Copyright © 2001 John Wiley & Sons, Ltd.
Secure key agreement for group communications
Authors: Yang Wen‐Her , Shieh Shiuh‐Pyng
Published: August 2002

A secure key agreement protocol for group communications is proposed in this paper, which ensures the authenticity of group members and the privacy of group messages, and provides the properties of perfect forward and backward privacy. In a group session, the common key is collaboratively established by all participants, hence the overhead of key agreement is balanced among group members. Copyright © 2001 John Wiley & Sons, Ltd.
Worst‐case ratios of networks in the rectilinear plane
Authors: Brenner Ulrich , Vygen Jens
Published: August 2002

For point sets in the rectilinear plane, we consider the following five measures of the interconnect length and prove bounds on the worst‐case ratio: minimum Steiner tree, minimum star, clique, minimum spanning tree, and bounding box. In particular, we prove that, for any set of n points, (n − 1) times the shortest Steiner tree is less or equal to the clique unless n = 4 and the minimum spanning tree is less or equal to the shortest star unless n ∈ {3, 4, 5}. © 2001 John Wiley & Sons, Inc.
Bitter substances suppress afferent responses to an appetitive mixture: Evidence for peripheral integration of chemosensory stimuli
Authors: Li Yuxing , Perruccio Elizabeth , Zhang Xian , Kleinhaus Anna L.
Published: August 2002

The processes that lead from detection of chemicals, transduction, and coding with the appropriate message to initiate ingestion of a palatable meal or to reject a potentially noxious substance are poorly understood in vertebrates owing to the complex organization of the taste system. As a first step in elucidating the cellular basis of the behavioral differences elicited by appetitive stimuli and bitter compounds, we recorded from the afferent nerves conveying peripheral chemosensory information to the CNS in the head of the leech, Hirudo medicinalis. Superfusion of the chemosensory region of the lip of Hirudo with a mixture of NaCl (150 mM) and arginine (1 mM), an appetitive solution that elicits ingestion, increased the neuronal activity in the afferent cephalic nerves, for example (Zhang X, Wilson RJ, Li Y, Kleinhaus AL. 2000. Chemical and thermal stimuli have short‐lived effects on the Retzius cell in the medicinal leech. J Neurobiol 43:304–311.). In the present paper we show that superfusing the lip with quinine or denatonium reduced the basal neural activity in the afferents. Furthermore, these bitter substances in the appetitive solution counteracted the increased activity the appetitive solution evoked in the cephalic nerves. Thus, the neural activity evoked by the application of appetitive and aversive stimuli to the chemosensory area of the lip paralleled the opposite behavioral responses to the same chemicals. The results suggest that individual leech taste cells possess receptors for both types of stimuli. Therefore, the leech may be a good model system in which to study peripheral taste events in cells that may possess multiple receptors and transduction mechanisms that interact to integrate information. © 2001 John Wiley & Sons, Inc. J Neurobiol 49: 255–263, 2001
Steps in the formation of a bipolar outgrowth pattern by cultured neurons, and their substrate dependence
Authors: de‐Miguel Francisco F. , Vargas Javier
Published: August 2002

We studied the steps in the formation of the bipolar outgrowth pattern of cultured adult Anterior Pagoda (AP) neurons of the leech growing on a central nervous system (CNS) homogenate as substrate. This pattern, which consists of two primary neurites directed in opposite directions plus some bifurcations, resembles their embryonic pattern but is different from the patterns they develop in culture on leech laminin or Concanavalin A as substrates. In eight neurons that were studied, one primary neurite formed and branched several hours before the second one. Time‐lapse video analysis showed that between 12 and 36 h of growth, the more proximal branch of the early neurite migrated retrogradely, rotated, and formed the second primary branch. Both neurites elongated until the total neurite length reached 130–160 μm, when the elongation of primary neurites became synchronous with the retraction of secondary processes, suggesting competition. The substrate dependence of these events was tested by plating AP neurons on leech laminin. On this substrate AP neurons produced multiple independent primary neurites with branches. Retraction of some large branches was followed by their regrowth, and did not correlate with the changes in other neurites. We propose that the dynamics in the formation of the bipolar outgrowth pattern of AP neurons arise from inhibitory extracellular matrix molecules, which reduce the synthesis of precursors for neurite formation. © 2002 Wiley Periodicals, Inc. J Neurobiol 50: 106–117, 2002; DOI 10.1002/neu.10017
Regulated appearance of NMDA receptor subunits and channel functions during in vitro neuronal differentiation
Authors: Jelitai Márta , Schlett Katalin , Varju Patrícia , Eisel Ulrich , Madarász Emília
Published: August 2002

The schedule of NMDA receptor subunit expression and the appearance of functional NMDA‐gated ion channels were investigated during the retinoic acid (RA) induced neuronal differentiation of NE‐4C, a p53‐deficient mouse neuroectodermal progenitor cell line. NR2A, NR2B, and NR2D subunit transcripts were present in both nondifferentiated and neuronally differentiated cultures, while NR2C subunits were expressed only transiently, during the early period of neural differentiation. Several splice variants of NR1 were detected in noninduced progenitors and in RA‐induced cells, except the N1 exon containing transcripts that appeared after the fourth day of induction, when neuronal processes were already formed. NR1 and NR2A subunit proteins were detected both in nondifferentiated progenitor cells and in neurons, while the mature form of NR2B subunit protein appeared only at the time of neuronal process elongation. Despite the early presence of NR1 and NR2A subunits, NMDA‐evoked responses could be detected in NE‐4C neurons only after the sixth day of induction, coinciding in time with the expression of the mature NR2B subunit. The formation of functional NMDA receptors also coincided with the appearance of synapsin I and synaptophysin. The lag period between the production of the subunits and the onset of channel function suggests that subunits capable of channel formation cannot form functional NMDA receptors until a certain stage of neuronal commitment. Thus, the in vitro neurogenesis by NE‐4C cells provides a suitable tool to investigate some inherent regulatory processes involved in the initial maturation of NMDA receptor complexes. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 54–65, 2002
Behavioral discrimination of sexually dimorphic calls by male zebra finches requires an intact vocal motor pathway
Authors: Vicario David S. , Naqvi Nasir H. , Raksin Jonathan N.
Published: August 2002

Vocal communication between zebra finches includes the exchange of long calls (LCs) as well as song. By using this natural call behavior and quantifying the LCs emitted in response to playbacks of LCs of other birds, we have previously shown that adult male zebra finches have a categorical preference for the LCs of females over those of males. Female LCs are acoustically simpler than male LCs, which include complex acoustic features that are learned during development. Production of these male‐typical features requires an intact nucleus RA, the sexually dimorphic source of the main telencephalic projection to brainstem vocal effectors. We have now made bilateral lesions of RA in 17 adult males and tested their discrimination behavior in the call response situation. Lesioned birds continue to call, but lose the male‐typical preference for female LCs. The degree of loss is correlated with the extent of RA damage. Further, the simplified LCs of males with RA lesions have a variable duration that is correlated with stimulus features. In effect, the call response behavior of lesioned males becomes like that of females. Apparently, in the absence of RA, the remaining intact structures receive different call information than RA normally does, and/or process it differently. This suggests that the vocal motor nucleus RA could play a role in the transformation of a signal encoding the salience of stimulus parameters into a control signal that modulates the probability and strength of responding. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 109–120, 2001
New reproductive anomalies in fruitless‐mutant Drosophila males: Extreme lengthening of mating durations and infertility correlated with defective serotonergic innervation of reproductive organs
Authors: Lee Gyunghee , Villella Adriana , Taylor Barbara J. , Hall Jeffrey C.
Published: August 2002

Several features of male reproductive behavior are under the neural control of fruitless (fru) in Drosophila melanogaster. This gene is known to influence courtship steps prior to mating, due to the absence of attempted copulation in the behavioral repertoire of most types of fru‐mutant males. However, certain combinations of fru mutations allow for fertility. By analyzing such matings and their consequences, we uncovered two striking defects: mating times up to four times the normal average duration of copulation; and frequent infertility, regardless of the time of mating by a given transheterozygous fru‐mutant male. The lengthened copulation times may be connected with fru‐induced defects in the formation of a male‐specific abdominal muscle. Production of sperm and certain seminal fluid proteins are normal in these fru mutants. However, analysis of postmating qualities of females that copulated with transheterozygous mutants strongly implied defects in the ability of these males to transfer sperm and seminal fluids. Such abnormalities may be associated with certain serotonergic neurons in the abdominal ganglion in which production of 5HT is regulated by fru. These cells send processes to contractile muscles of the male's internal sex organs; such projection patterns are aberrant in the semifertile fru mutants. Therefore, the reproductive functions regulated by fruitless are expanded in their scope, encompassing not only the earliest stages of courtship behavior along with almost all subsequent steps in the behavioral sequence, but also more than one component of the culminating events. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 121–149, 2001
Simulations of flow through fluid/porous layers by a characteristic‐based method on unstructured grids
Authors: Zhang Baili , Zhao Yong
Published: August 2002

An upwind characteristic‐based finite volume method on unstructured grids is employed for numerical simulation of incompressible laminar flow and forced convection heat transfer in 2D channels containing simultaneously fluid layers and fluid‐saturated porous layers. Hydrodynamic and heat transfer results are reported for two configurations: the first one is a backward‐facing step channel with a porous block inserted behind the step, and the second one is a partially porous channel with discrete heat sources on the bottom wall. The effects of Darcy numbers on heat transfer augmentation and pressure loss were investigated for low Reynolds laminar flows. The results demonstrate the accuracy and robustness of the numerical scheme proposed, and suggest that partially porous insertion in a channel can significantly improve heat transfer performance with affordable pressure loss. Copyright © 2001 John Wiley & Sons, Ltd.
Adaptive return mapping algorithms for J2 elasto‐viscoplastic flow
Authors: Lof J. , van den Boogaard A. H.
Published: August 2002

In this paper a new class of integration algorithms for elasto‐viscoplastic constitutive equations is proposed. It is based on the generalized trapezoidal rule, which is a weighted combination of the start and end of the increment. But instead of taking constant weights, the weights are a function of the plastic multiplier. In this way the magnitude of the plastic‐strain increment determines the way the integration is performed. The stress update and consistent tangent are derived for the case of J2 flow. Several candidates within the class of adaptive return mapping algorithms are investigated. It is shown numerically that some of the proposed algorithms are more accurate than commonly used algorithms such as mean normal and radial return. Copyright © 2001 John Wiley & Sons, Ltd.
Boundary elements for half‐space problems via fundamental solutions: A three‐dimensional analysis
Authors: Liang J. , Liew K. M.
Published: August 2002

An efficient solution technique is proposed for the three‐dimensional boundary element modelling of half‐space problems. The proposed technique uses alternative fundamental solutions of the half‐space (Mindlin's solutions for isotropic case) and full‐space (Kelvin's solutions) problems. Three‐dimensional infinite boundary elements are frequently employed when the stresses at the internal points are required to be evaluated. In contrast to the published works, the strongly singular line integrals are avoided in the proposed solution technique, while the discretization of infinite elements is independent of the finite boundary elements. This algorithm also leads to a better numerical accuracy while the computational time is reduced. Illustrative numerical examples for typical isotropic and transversely isotropichalf‐space problems demonstrate the potential applications of the proposed formulations. Incidentally, the results of the illustrative examples also provide a parametric study for the imperfect contact problem. Copyright © 2001 John Wiley & Sons, Ltd.
Topological aspects of meshless methods and nodal ordering for meshless discretizations
Authors: Yavari Arash , Kaveh Ali , Sarkani Shahram , Bondarabady Hosein Ali Rahimi
Published: August 2002

The meshless element‐free Galerkin method (EFGM) is considered and compared to the finite‐element method (FEM). In particular, topological aspects of meshless methods as the nodal connectivity and invertibility of matrices are studied and compared to those of the FE method. We define four associated graphs for meshless discretizations of EFGM and investigate their connectivity. The ways that the associated graphs for coupled FE‐EFG models might be defined are recommended. The associated graphs are used for nodal ordering of meshless models in order to reduce the bandwidth, profile, maximum frontwidth, and root‐mean‐square wavefront of the corresponding matrices. Finally, the associated graphs are numerically compared. Copyright © 2001 John Wiley & Sons, Ltd.
An algebraic two‐level preconditioner for asymmetric, positive‐definite systems
Authors: Giddings Thomas E. , Fish Jacob
Published: August 2002

A two‐level, linear algebraic solver for asymmetric, positive‐definite systems is developed using matrices arising from stabilized finite element formulations to motivate the approach. Supported by an analysis of a representative smoother, the parent space is divided into oscillatory and smooth subspaces according to the eigenvectors of the associated normal system. Using a mesh‐based aggregation technique, which relies only on information contained in the matrix, a restriction/prolongation operator is constructed. Various numerical examples, on both structured and unstructured meshes, are performed using the two‐level cycle as the basis for a preconditioner. Results demonstrate the complementarity between the smoother and the coarse‐level correction as well as convergence rates that are nearly independent of the problem size. Copyright © 2001 John Wiley & Sons, Ltd.
A robust dual algorithm for topology design of structures in discrete variables
Authors: Jog C. S.
Published: August 2002

Dual optimization algorithms for the topology optimization of continuum structures in discrete variables are gaining popularity in recent times since, in topology design problems, the number of constraints is small in comparison to the number of design variables. Good topologies can be obtained for the minimum compliance design problem when the perimeter constraint is imposed in addition to the volume constraint. However, when the perimeter constraint is relaxed, the dual algorithm tends to give bad results, even with the use of higher‐order finite element models as we demonstrate in this work. Since, a priori, one does not know what a good value of the perimeter to be specified is, it is essential to have an algorithm which generates good topologies even in the absence of the perimeter constraint. We show how the dual algorithm can be made more robust so that it yields good designs consistently in the absence of the perimeter constraint. In particular, we show that the problem of checkerboarding which is frequently observed with the use of lower‐order finite elements is eliminated. Copyright © 2001 John Wiley & Sons, Ltd.
Extraction of boundary representation from surface triangulations
Authors: Krysl Petr , Ortiz Michael
Published: August 2002

Many computational science tools employ finite element meshes as discretizations of the geometrical domains, and automatic mesh generation has become an indispensable part of the discretization process. Boundary representations (BRep) of solids are the means of describing the geometrical model to the mesher, thus enabling the generator to proceed without user intervention. Significant effort has been devoted in the past to BRep construction in the frame‐work of solid modelling systems. In this paper we consider the task of converting a tesselation (triangulation) of the surface of a solid into a BRep, and propose a robust and efficient set of algorithms for this purpose. Applications include, among others, remeshing of finite element discretizations during simulations involving not only geometric distortion but also changes in topology (coalescence and fragmentation of solids, flow, and so on). Copyright © 2001 John Wiley & Sons, Ltd.
John Deere optimizes operations with supply management efforts
Authors: Nelson R. David
Published: August 2002

Recognizing that 70 percent of the costs of its manufactured products occur externally, John Deere has
embarked on a series of supply chain best practices that is already producing millions of dollars of cost
savings. Improved logistics at the company has reduced transportation costs, standardized shipping containers
(reducing 43 types to three), and developed one order process companywide rather than having 20
factories use their own, different ones. Beyond logistics, Deere has formalized new strategies for selecting
suppliers, creating lean supplies, managing supply chain costs, integrating supplies into the product development
process, and utilizing e‐procurement. These are all steps toward Deere's overall goal: to design
products that delight customers at the lowest total cost and design out waste and inefficiency early in the
product development process. © 2002 Wiley Periodicals, Inc.
Currents: Articles in Brief
Authors: Green Rachael
Published: August 2002

Seven Strategies for Retaining Top Talent

Five Ways to Re‐recruit Your Employees

Building an Effective Global Business Team

Lead for Loyalty

Do the Right Thing

Making Performance Management Relevant

Can Pay for Performance Really Work?
A stereological investigation on the effects of forebrain ischemia on hippocampal neuron number in chick
Authors: Canan S. , Pakkenberg B. , Kaplan S. , Aslan H.
Published: August 2002

Seven days after 10 minutes bilateral occlusion of internal carotid arteries, the total neuron number and the volume of the hippocampus were estimated using the optical fractionator method for cell counting and Cavalieri’s principle for volume estimation. After comparing with sham‐operated animals, no significant difference in total neuron number was observed in hippocampi of ischemic chicks; a statistically significant increase in numerical density of hippocampal neurons in hippocampi of ischemic group (p<0.05) could well be explained as a decrease, although statistically insignificant, of the hippocampal volume. These results indicate that, the ischemia model and/or its duration is not sufficient to induce a detectable neuronal loss but it induces a reduction in the volume of hippocampus. It also indicates that 10 minutes ischemia is too short a test period to induce a neuronal cell loss in hippocampus of young domestic chicks.
Long‐term maternal ethanol administration decreases nitric oxide metabolites in brains of postnatal mice
Authors: Nagatomo Itsugi , Hashiguchi Wataru , Tominaga Masataka , Uchida Masahiro , Akasaki Yasuaki , Takigawa Morikuni
Published: August 2002

We examined the effect of long‐term maternal ethanol consumption on nitric oxide metabolites (NOx) in brains of postnatal mice. Three female adult ddY mice were given 10% ethanol solution ad libitum as drinking water for a 4 weeks before mating and continued on their corresponding ethanol solution during gestation and lactation. Other 2 mice receiving tap water ad libitum during gestation and lactation served as controls. The offspring in both groups were weaned at 22 days of age, and they were maintained on the chow and water ad libitum. In brain NOx levels in the offspring at 42 days of age, offspring with maternal alcohol consumption were significantly lower than those in controls, but serum NOx levels did not differ between groups. No significant differences in monoamines in the brain were evident between offspring with and without maternal alcohol administration. Present results indicated that long‐term maternal ethanol administration reduced brain NO metabolite levels in offspring, but not serum NO metabolites or brain monoamines.
Utility of retrospective pretest ratings of patient satisfaction with health status§
Authors: Kreulen Grace J. , Stommel Manfred , Gutek Barbara A. , Burns Lawton R. , Braden Carrie Jo
Published: August 2002

Outcomes assessment is often difficult to accomplish in evaluation research studies in situations where the gathering of pretest data is impossible or prohibitively expensive. The purpose of this longitudinal study was to investigate the substitutability of retrospective pretest ratings for actual pretest ratings in indexing change in patient satisfaction with health status. The sample consisted of 251 women receiving medical treatment for breast cancer enrolled in the Self‐Help Intervention Project (SHIP). ANOVA, ordinary least‐squares regression, and pooled time‐series regression analysis revealed that retrospective assessments were not significantly different from their prospective counterparts in means and variances and that they differed from current assessments taken at the same time (p<.01). In addition, prospective assessments emerged as a significant independent predictor of corresponding retrospective scores (p<.01), accounting for up to 30% of the recall scores. These findings have implications for inclusion of retrospective pre–post comparisons in outcomes evaluation research. © 2002 Wiley Periodicals, Inc. Res Nurs Health 25:233–241, 2002
Biological rhythm development in preterm infants: Does health status influence body temperature circadian rhythm?
Authors: Thomas Karen A.
Published: August 2002

Twenty‐six preterm infants, postconceptional age from 28 to 35 weeks and postnatal age approximately 14 days, were included in a study of the development of temperature circadian rhythm. Insulated abdominal skin temperature and incubator air temperature were recorded continuously at 1‐min intervals for 24 hr. Using cosinor analysis, cycle mesor, amplitude, and acrophase were determined. Initial results from regression analysis did not confirm a predicted linear relationship between postconceptional age and amplitude; however, dividing the sample according to health status into sick (N = 15) and not sick (N = 11) groups revealed differing regression models. For not sick infants, amplitude increased with postconceptional age (R2 = .405), whereas no relationship was found between postconceptional age and cycle amplitude in sick infants (R2 = .069). These results indicate that healthy preterm infants demonstrate emergence of circadian temperature rhythm. Implications include potential time‐based periods of vulnerability, overheating and hyperthermia, and management of incubator operation. © 2001 John Wiley & Sons, Inc. Res Nurs Health 24: 170–180, 2001
Developmental outcomes of infants with bronchopulmonary dysplasia: Comparison with other medically fragile infants
Authors: Holditch‐Davis Diane , Docherty Sharron , Miles Margaret S. , Burchinal Margaret
Published: August 2002

The purpose of this study was to compare the developmental outcomes and mother–infant interactions of infants with bronchopulmonary dysplasia (BPD) and those of other medically fragile infants. One‐hour behavioral observations were made of the interactions of mothers with two groups of infants (23 with BPD, 39 medically fragile without BPD or neurological problems) at enrollment, every 2 months during hospitalization, 1 month after discharge, and at 6 months' and 12 months' corrected age. Assessment of the home environment also was done at 6 and 12 months. Multiple regressions were calculated separately for child mental, adaptive, language, and motor outcomes. Predictors were: home environment assessment, measures of maternal interactive behaviors (positive attention, expression of negative affect, medicalized caregiving), infant group membership, and presence of intraventricular hemorrhage (IVH) in the infant. There were no significant differences between the two groups in any of the developmental outcomes or interactive variables, and the presence of IVH had no effect on these variables. Maternal positive attention and the home environment were correlated with mental development, and mother negative affect was related to adaptive behavior for both groups. Differences in developmental and interactive behaviors between infants with BPD and other prematurely born infants found in other studies appear to be a result of chronic health problems and, thus, are not unique to infants with BPD. © 2001 John Wiley & Sons, Inc. Res Nurs Health 24: 181–193, 2001
A possible case of hyperparathyroidism in a burial of 15–17th century AD date from Wharram Percy, England
Authors: Mays S. , Rogers J. , Watt I.
Published: August 2002

The subject of this paper is the partial skeleton of an adult female, dating to ad 1420–1640, excavated from the church at the deserted village of Wharram Percy, North Yorkshire, UK. Lesions are described which are probably indicative of hyperparathyroidism. Copyright © 2001 John Wiley & Sons, Ltd.
First palaeopathological example of Kienböck's disease from early modern Sakhalin Ainu
Authors: Nakai M. , Inoue K. , Hukuda S.
Published: August 2002

A disorder of the carpal lunate has been diagnosed as Kienböck's disease in a skeleton of a middle‐aged Ainu male that was excavated from Sakhalin Island, northeast Asia. The bone lesion is primarily and unilaterally associated with the right wrist, where the right carpal lunate is collapsed and the radiocarpal joint shows degenerative arthritis. Interestingly, the left arm is more robust than the right and the left elbow shows considerable osteoarthritis. The most plausible explanation for these pathologies is that after developing Kienböck's disease in the right wrist, excessive use of the left arm made his left arm robust and finally gave rise to osteoarthritis in the left elbow. In archaeology, where only a few osteochondroses have been reported up until now, the present example is the first diagnosis of Kienböck's disease in skeletal remains. Copyright © 2002 John Wiley & Sons, Ltd.
A case of skeletal tuberculosis from Roman Towcester
Authors: Anderson T.
Published: August 2002

An adult male from a Roman inhumation cemetery at Towcester, Northamptonshire, displays clear evidence of Pott's disease of the spine. This short report has been prompted by the fact that relatively few cases of skeletal tuberculosis have been identified from Roman contexts in Britain. Copyright © 2001 John Wiley & Sons, Ltd.
Metaphyseal fibrous defects in juveniles from medieval Norwich
Authors: Anderson T.
Published: August 2002

Two juvenile skeletons excavated from medieval Norwich each have a well‐defined cystic cavitation. One involves the distal femur and the other the proximal tibia. The dry bone and radiographic appearance, as well as the location and age of the individuals, support a diagnosis of metaphyseal cortical defects. Although well‐known in clinical practice, especially in children, this appears to be the first published evidence for the condition in British archaeological material. No other anomalies were detected on the two skeletons. However, the occurrence of two cases in the same cemetery raises the possibility of a genetic influence in the condition. Copyright © 2002 John Wiley & Sons, Ltd.