bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the initial dip in fMRI at 7 Tesla
Authors: Yacoub Essa , Shmuel Amir , Pfeuffer Josef , Van De Moortele Pierre‐Francois , Adriany Gregor , Ugurbil Kamil , Hu Xiaoping 
Published: August 2002

AbstractIn agreement with optical imaging studies, previous fMRI studies have reported an initial decrease (i.e. the initial dip) in the BOLD response, which is believed to arise from an increase in oxygen consumption and to be mostly microvascular. To date, experimental studies of the initial dip in humans have been performed at fields up to 4 T, with relatively low spatial resolution. Because the sensitivity to microvascular contribution is increased at high magnetic fields, the present study investigated the initial dip at 7 T. In addition, to reduce the partial volume effect, the study is conducted at a high spatial resolution. The initial dip was detected in all subjects studied and was found to reside mostly in the gray matter. The relative amplitude of the early response was found to be 0.6, higher than that at 4 T (0.3) and 1.5 T (0.11). In addition, based on the assumption that the initial dip is a result of increased oxygen utilization, the fractional change in oxygen utilization was estimated to be 40% of that of the fractional change in cerebral blood flow. These results are in agreement with the notion that the initial dip arises from an increase in oxygen consumption. Copyright © 2001 John Wiley & Sons, Ltd.
Abbreviations used:

CBF

cerebral blood flow

CMRO2

cerebral metabolic rate of oxygen

OVS

outer volume suppression

PVE

partial volume effect
Diffusion‐weighted in vivo localized proton MR spectroscopy of human cerebral ischemia and tumor
Authors: Harada Masafumi , Uno Masaaki , Hong Fang , Hisaoka Sonoka , Nishitani Hiromu , Matsuda Tsuyoshi 
Published: August 2002

AbstractThe apparent diffusion coefficients (ADCs) of water and brain metabolites were determined by proton MR spectroscopy on a clinical MR scanner for healthy volunteers and for pathological changes in cases of acute cerebral infarction and brain tumor. The ADCs of N‐acetyl aspartate (NAA) and creatines in tissue involved in acute infarction were decreased compared to normal control values, while in tumors they showed increased values. Since NAA is a neuronal marker, these findings suggest that neuronal cell viscosity changes according to the pathological status of the tissue. The lactate ADC was significantly larger than the values for other major metabolites in cases of ischemia and tumor, suggesting that lactate is present in a different compartment. These results indicate that metabolite diffusion data can be used to reveal changes in the intracellular environment depending on the pathological status. Copyright © 2002 John Wiley & Sons, Ltd.
The neurotrophin receptors, trkB and p75, differentially regulate motor axonal regeneration
Authors: Boyd J. G. , Gordon T. 
Published: August 2002

AbstractNeurotrophic factors that support neuronal survival are implicated in axonal regeneration after injury. Specifically, a strong role for BDNF in motor axonal regeneration has been suggested based on its pattern of expression after injury, as well as the expression of its receptors, trkB and p75. Despite considerable in vitro evidence, which demonstrate specific and distinct physiological responses elicited following trkB and p75 activation, relatively little is known about the function of these receptors in vivo. To investigate the roles of the trkB and p75 receptors in motor axonal regeneration, we have used a tibial (TIB)‐ common peroneal (CP) cross suture paradigm in p75 homozygous (−/−) knockout mice, trkB heterozygous (+/−) knockout mice, as well as in their wild‐type controls. Contralateral intact TIB motoneurons, and axotomized TIB motoneurons that regenerated their axons 10 mm into the CP distal nerve stump were identified by fluorescent retrograde tracers and counted in the T11‐L1 spinal segments. Regeneration was evaluated 2, 3, 4, 6, and 8 weeks after nerve repair. Compared to wild‐type animals, there are significantly fewer intact TIB motoneurons in p75 (−/−), but not trkB (+/−) mice. The number of motoneurons that regenerated their axons was significantly increased in the p75 (−/−) knockout mice, but significantly attenuated in the trkB (+/−) mice compared to wild‐type controls. These results suggest that p75 is important for motoneuronal survival during development, but p75 expression after injury serves to inhibit motor axonal regeneration. In addition, full expression of trkB is critical for complete axonal regeneration to proceed. © 2001 John Wiley & Sons, Inc. J Neurobiol 49: 314–325, 2001
Chronic alterations in serotonin function: Dynamic neurochemical properties in agonistic behavior of the crayfish, Orconectes rusticus
Authors: Panksepp Jules B. , Huber Robert 
Published: August 2002

AbstractThe biogenic amine serotonin [5‐hydroxytryptamine (5‐HT)] has received considerable attention for its role in behavioral phenomena throughout a broad range of invertebrate and vertebrate taxa. Acute 5‐HT infusion decreases the likelihood of crayfish to retreat from dominant opponents. The present study reports the biochemical and behavioral effects resulting from chronic treatment with 5‐HT‐modifying compounds delivered for up to 5 weeks via silastic tube implants. High performance liquid chromatography with electrochemical detection (HPLC‐ED) confirmed that 5,7‐dihydroxytryptamine (5,7‐DHT) effectively reduced 5‐HT in all central nervous system (CNS) areas, except brain, while a concurrent accumulation of the compound was observed in all tissues analyzed. Unexpectedly, two different rates of chronic 5‐HT treatment did not increase levels of the amine in the CNS. Behaviorally, 5,7‐DHT treated crayfish exhibited no significant differences in measures of aggression. Although treatment with 5‐HT did not elevate 5‐HT content in the CNS, infusion at a slow rate caused animals to escalate more quickly while 5‐HT treatment at a faster rate resulted in slower escalation. 5,7‐DHT is commonly used in behavioral pharmacology and the present findings suggest its biochemical properties should be more thoroughly examined. Moreover, the apparent presence of powerful compensatory mechanisms indicates our need to adopt an increasingly dynamic view of the serotonergic bases of behavior like crayfish aggression. © 2002 Wiley Periodicals, Inc. J Neurobiol 50: 276–290, 2002; DOI 10.1002/neu.10035
Stimulation of nitric oxide synthase in cerebral cortex due to elevated partial pressures of oxygen: An oxidative stress response
Authors: Thom Stephen R. , Bhopale Veena , Fisher Donald , Manevich Yefim , Huang Paul L. , Buerk Donald G. 
Published: August 2002

AbstractThe purpose of this investigation was to determine the impact of elevated partial pressures of O2 on the steady state concentration of nitric oxide (•NO) in the cerebral cortex. Rodents with implanted O2‐ and •NO‐specific microelectrodes were exposed to O2 at partial pressures from 0.2 to 2.8 atmospheres absolute (ATA) for up to 45 min. Elevations in •NO concentration occurred with all partial pressures above that of ambient air. In rats exposed to 2.8 ATA O2 the increase was 692 ± 73 nM (S.E., n = 5) over control. Changes were not associated with alterations in concentrations of nitric oxide synthase (NOS) enzymes. Based on studies with knock‐out mice lacking genes for neuronal NOS (nNOS) or endothelial NOS (eNOS), nNOS activity contributed over 90% to total •NO elevation due to hyperoxia. Immunoprecipitation studies indicated that hyperoxia doubles the amount of nNOS associated with the molecular chaperone, heat shock protein 90 (Hsp90). Both •NO elevations and the association between nNOS and Hsp90 were inhibited in rats infused with superoxide dismutase. Elevations of •NO were also inhibited by treatment with the relatively specific nNOS inhibitor, 7 nitroindazole, by the ansamycin antibiotics herbimycin and geldanamycin, by the antioxidant N‐acetylcysteine, by the calcium channel blocker nimodipine, and by the N‐methyl‐D‐aspartate inhibitor, MK 801. Hyperoxia did not alter eNOS association with Hsp90, nor did it modify nNOS or eNOS associations with calmodulin, the magnitude of eNOS tyrosine phosphorylation, or nNOS phosphorylation via calmodulin kinase. Cerebral cortex blood flow, measured by laser Doppler flow probe, increased during hyperoxia and may be causally related to elevations of steady state •NO concentration. We conclude that hyperoxia causes an increase in •NO synthesis as part of a response to oxidative stress. Mechanisms for nNOS activation include augmentation in the association with Hsp90 and intracellular entry of calcium. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 85–100, 2002
Conditional modification of behavior inDrosophilaby targeted expression of a temperature‐sensitiveshibireallele in defined neurons
Authors: Kitamoto Toshihiro 
Published: August 2002

AbstractBehavior is a manifestation of temporally and spatially defined neuronal activities. To understand how behavior is controlled by the nervous system, it is important to identify the neuronal substrates responsible for these activities, and to elucidate how they are integrated into a functional circuit. I introduce a novel and general method to conditionally perturb anatomically defined neurons in intactDrosophila. In this method, a temperature‐sensitive allele ofshibire(shits1) is overexpressed in neuronal subsets using theGAL4/UASsystem. Because theshigene product is essential for synaptic vesicle recycling, andshits1is semidominant, a simple temperature shift should lead to fast and reversible effects on synaptic transmission ofshits1expressing neurons. Whenshits1expression was directed to cholinergic neurons, adult flies showed a dramatic response to the restrictive temperature, becoming motionless within 2 min at 30°C. This temperature‐induced paralysis was reversible. After being shifted back to the permissive temperature, they readily regained their activity and started to walk in 1 min. Whenshits1was expressed in photoreceptor cells, adults and larvae exhibited temperature‐dependent blindness. These observations show that theGAL4/UASsystem can be used to expressshits1in a specific subset of neurons to cause temperature‐dependent changes in behavior. Because this method allows perturbation of the neuronal activities rapidly and reversibly in a spatially and temporally restricted manner, it will be useful to study the functional significance of particular neuronal subsets in the behavior of intact animals. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 81–92, 2001
Visualization of neuropeptide expression, transport, and exocytosis in Drosophila melanogaster
Authors: Rao Sujata , Lang Cynthia , Levitan Edwin S. , Deitcher David L. 
Published: August 2002

AbstractNeuropeptides affect an extremely diverse set of physiological processes. Neuropeptides are often coreleased with neurotransmitters but, unlike neurotransmitters, the neuropeptide target cells may be distant from the site(s) of secretion. Thus, it is often difficult to measure the amount of neuropeptide release in vivo by electrophysiological methods. Here we establish an in vivo system for studying the developmental expression, processing, transport, and release of neuropeptides. A GFP‐tagged atrial natriuretic factor fusion (preproANF‐EMD) was expressed in the Drosophila nervous system with the panneural promoter, elav. During embryonic development, proANF‐EMD was first seen to accumulate in synaptic regions of the CNS in stage 17 embryos. By the third instar larval stage, highly fluorescent neurons were evident throughout the CNS. In the adult, fluorescence was pronounced in the mushroom bodies, antennal lobe, and the central complex. At the larval neuromuscular junction, proANF‐EMD was concentrated in nerve terminals. We compared the release of proANF‐EMD from synaptic boutons of NMJ 6/7, which contain almost exclusively glutamate‐containing clear vesicles, to those of NMJ 12, which include the peptidergic type III boutons. Upon depolarization, approximately 60% of the tagged neuropeptide was released from NMJs of both muscles in 15 min, as assayed by decreased fluorescence. Although the elav promoter was equally active in the motor neurons that innervate both NMJs 6/7 and 12, NMJ 12 contained 46‐fold more neuropeptide and released much more proANF‐EMD during stimulation than did NMJ 6/7. Our results suggest that peptidergic neurons have an enhanced ability to accumulate and/or release neuropeptides as compared to neurons that primarily release classical neurotransmitters. © 2001 John Wiley & Sons, Inc. J Neurobiol 49: 159–172, 2001
A posteriori error estimation for elliptic eigenproblems
Authors: Neymeyr Klaus 
Published: August 2002

AbstractAn a posteriori error estimator is presented for a subspace implementation of preconditioned inverse iteration, which derives from the well‐known inverse iteration in such a way that the associated system of linear equations is solved approximately by using a preconditioner. The error estimator is integrated in an adaptive multigrid algorithm to compute approximations of a modest number of the smallest eigenvalues together with the eigenfunctions of an elliptic differential operator.Error estimation is applied both within the actual finite element space (in order to estimate the iteration error) as well as in its hierarchical refinement of higher‐order elements (to estimate the discretization error) which gives rise to a balanced reduction of the iteration error and of the discretization error in the adaptive multigrid algorithm. Copyright © 2002 John Wiley & Sons, Ltd.
Filters in topology optimization
Authors: Bourdin Blaise 
Published: August 2002

AbstractIn this article, a modified (‘filtered’) version of the minimum compliance topology optimization problem is studied. The direct dependence of the material properties on its pointwise density is replaced by a regularization of the density field by the mean of a convolution operator. In this setting it is possible to establish the existence of solutions. Moreover, convergence of an approximation by means of finite elements can be obtained. This is illustrated through some numerical experiments. The ‘filtering’ technique is also shown to cope with two important numerical problems in topology optimization, checkerboards and mesh dependent designs. Copyright © 2001 John Wiley & Sons, Ltd.
A new method for modelling cohesive cracks using finite elements
Authors: Wells G. N. , Sluys L. J. 
Published: August 2002

AbstractA model which allows the introduction of displacements jumps to conventional finite elements is developed. The path of the discontinuity is completely independent of the mesh structure. Unlike so‐called ‘embedded discontinuity’ models, which are based on incompatible strain modes, there is no restriction on the type of underlying solid finite element that can be used and displacement jumps are continuous across element boundaries. Using finite element shape functions as partitions of unity, the displacement jump across a crack is represented by extra degrees of freedom at existing nodes. To model fracture in quasi‐brittle heterogeneous materials, a cohesive crack model is used. Numerical simulations illustrate the ability of the method to objectively simulate fracture with unstructured meshes. Copyright © 2001 John Wiley & Sons, Ltd.
Parameter identification with weightless regularization
Authors: Furukawa Tomonari 
Published: August 2002

AbstractAlthough the regularization increased the popularity of parameter identification due to its capability of deriving a stable solution, the significant problem is that the solution depends upon the regularization parameters chosen. This paper presents a technique for deriving solutions without the use of the parameters and, further, an optimization method, which can work efficiently for problems of concern. Numerical examples show that the technique can efficiently search for appropriate solutions. Copyright © 2001 John Wiley & Sons, Ltd.
The computation of the exponential and logarithmic mappings and their first and second linearizations
Authors: Ortiz M. , Radovitzky R. A. , Repetto E. A. 
Published: August 2002

AbstractWe describe two simple methods for the evaluation of the exponential and logarithmic mappings and their first and second linearizations based on the Taylor expansion and the spectral representation. We also provide guidelines for switching between those representations on the basis of the size of the argument. The first and second linearizations of the exponential and logarithmic mappings provided here are based directly on the exponential formula for the solutions of systems of linear ordinary differential equations. This representation does not require the use of perturbation formulae for eigenvalues and eigenvectors. Our approach leads to workable and straightforward expressions for the first and second linearizations of the exponential and logarithmic mappings regardless of degeneracies in the spectral decomposition of the argument. Copyright © 2001 John Wiley & Sons, Ltd.
Fleet Financial and Radcliffe Explore Paths of Work/Life Integration
Authors: Bailyn Lotte , Rayman Paula , Bengtsen Dale , Carré Françoise , Tierney Mark 
Published: August 2002

AbstractMany organizations have used the redesign of jobs—work processes, schedules, work loads, task assignments—as a strategy for improving productivity and other measures of bottom‐line effectiveness. Far fewer have recognized that job redesign can be a fundamental, critical strategy for the achievement of work/life balance. Most organizations still conceive of productivity and work/life balance as separate goals to be reached by different paths.The Radcliffe‐Fleet Work and Life Integration Project directly addresses this split. The Fleet Financial Group, emerging from a period of sweeping internal and external change, saw the need to improve its service and to improve its standing as an employer of choice. The Radcliffe Public Policy Institute was eager to conduct a project to demonstrate the principle that redesign of jobs can further the dual goals of improved service and work/life balance. © 2001 John Wiley & Sons, Inc.
Transition to home care after stroke: Depression, physical health, and adaptive processes in support persons
Authors: King Rosemarie B. , Carlson Carolyn E. , Shade‐Zeldow Yvonne , Bares Kimberly K. , Roth Elliot J. , Heinemann Allen W. 
Published: August 2002

AbstractA longitudinal design was used to examine adaptation in primary support persons (PSP) of stroke survivors during the transition from hospitalization (T1) to home care (T2). The major purposes of the study were (a) to examine changes in depression, physical health, and contextual and coping factors from hospitalization of the stroke survivor through the first 6–10 weeks of home care; and (b) to identify predictors of depression. Data (N = 136) were collected on depression, physical health, background, survivor illness, and social environmental variables; appraisal of impact; social support resources; and coping skills. Reduction in mean PSP depression was significant at T2, but the change in physical health was not significant. Significant changes occurred in survivor function, family functioning, and three of six coping skills. Hierarchical multiple regression analyses were used to predict depression. T1 variables accounted for 29% of the variance in T1 PSP depression, with gender and appraisal of impact the strongest of seven predictors. T1 depression, T2 health, family functioning, and avoidance coping were the strongest of seven predictors, explaining 50% of the variance in T2 depression. Findings highlight the importance of maintaining caregiver health and preventing depression and identify variables to target for the reduction of PSP depression. © 2001 John Wiley & Sons, Inc. Res Nurs Health 24:307–323, 2001
Enamel hypoplasia in Danish and Lithuanian Late Medieval/Early Modern samples: a possible reflection of child morbidity and mortality patterns
Authors: Palubeckaitė Žydrūnė , Jankauskas Rimantas , Boldsen Jesper 
Published: August 2002

AbstractNumerous studies and various interpretations of the prevalence of linear enamel hypoplasias (LEH) based on populations living in different cultural and economic conditions are causing some confusion and raising doubts about whether or not such LEH are reliable indicators of life conditions. An analysis of LEH prevalence patterns was performed on the adults of three populations: Tirup—a Danish Medieval rural population of the 12–14th centuries (131 individuals), Subačiaus str. in Vilnius—a Lithuanian Late Medieval urban population of the 16–17th centuries (88 individuals), and the aristocracy—a Lithuanian pooled sample population from several churches of the 15–18th centuries (66 individuals). Statistical testing of the influence of population affinity, sex and age at death was also performed. Since the same investigator scored all the samples, possible inter‐observer error bias was minimized.In all the populations, LEH formation ages were similar. Statistically significant sex differences were found only in the aristocratic sample (with higher male frequency). It was found that the town population was characterized by the highest frequency of affected individuals, with the highest severity and highest number of stress episodes per individual. A reliable relationship with age at death was found only in the town sample: individuals with more numerous and more marked LEH had shorter life expectancies in adulthood. Different “most vulnerable years” for subsequent life expectancies were noted for different populations. A tentative explanation of these differences could be the pooled effect of differential morbidity and mortality. It seems that the rural population experienced the highest morbidity and nutrition deficiency as well as the highest child mortality whereas, in the urban sample, high morbidity was accompanied by a lower child mortality. Both lower morbidity and mortality seem to be characteristic for the aristocracy. Copyright © 2002 John Wiley & Sons, Ltd.
Social and ritual determinants of whale bone transport at a classic Thule winter site in the Canadian Arctic
Authors: Whitridge Peter 
Published: August 2002

AbstractRecent research has demonstrated that patterning related to harvesting selectivity and architectural bone utilization persists in the surface distribution of bowhead whale (Balaena mysticetus) bones at classic Thule sites in the Canadian central Arctic, despite scavenging by later non‐whaling Inuit groups. Since skeletal riders with minimal architectural or artifactual utility are associated with carcass portions that were socially and ritually prized ethnographically in North Alaska, this surface record may also preserve spatial structure relating to loci of high status settlement and/or ceremonial activity within sites. Close to 3400 bowhead bones were mapped at the major Thule winter village of Qariaraqyuk, southeast Somerset Island. The results of a principal components analysis of the element distributions are consistent with expectations for special treatment of bowhead flippers, tails, and tongues. These results are supported by excavation data which reveal that flipper and tongue bones were preferentially discarded in the vicinity of wealthy whaling households and a major ceremonial structure. Contrary to the longstanding belief that Thule whale bone assemblages are hopelessly compromised by prehistoric and historic bone transport, these assemblages hold great promise for investigating Thule social and ritual practices. Copyright © 2002 John Wiley & Sons, Ltd.