bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of an MEG eigenspace beamformer to reconstructing spatio‐temporal activities of neural sources
Authors: Sekihara Kensuke , Nagarajan Srikantan S. , Poeppel David , Marantz Alec , Miyashita Yasushi 
Published: August 2002

AbstractWe have applied the eigenspace‐based beamformer to reconstruct spatio‐temporal activities of neural sources from MEG data. The weight vector of the eigenspace‐based beamformer is obtained by projecting the weight vector of the minimum‐variance beamformer onto the signal subspace of a measurement covariance matrix. This projection removes the residual noise‐subspace component that considerably degrades the signal‐to‐noise ratio (SNR) of the beamformer output when errors in estimating the sensor lead field exist. Therefore, the eigenspace‐based beamformer produces a SNR considerably higher than that of the minimum‐variance beamformer in practical situations. The effectiveness of the eigenspace‐based beamformer was validated in our numerical experiments and experiments using auditory responses. We further extended the eigenspace‐based beamformer so that it incorporates the information regarding the noise covariance matrix. Such a prewhitened eigenspace beamformer was experimentally demonstrated to be useful when large background activity exists. Hum. Brain Mapping 15:199–215, 2002. © 2002 Wiley‐Liss, Inc.
Event‐related changes in neuromagnetic activity associated with syncopation and synchronization timing tasks
Authors: Mayville Justine M. , Fuchs Armin , Ding Mingzhou , Cheyne Douglas , Deecke Lüder , Kelso J.A. Scott 
Published: August 2002

AbstractFor low rhythmic rates (1.0 to ∼2.0 Hz), subjects are able to successfully coordinate finger flexion with an external metronome in either a syncopated (between the beats) or synchronized (on each beat) fashion. Beyond this rate, however, syncopation becomes unstable and subjects spontaneously switch to synchronization to maintain a 1:1 stimulus/response relationship. We used a whole‐head magnetometer to investigate the spatiotemporal dynamics of neuromagnetic activity (MEG) associated with both coordinative patterns at eight different rates spanning the range 1.0–2.75 Hz. Timing changes in the event‐related fields accompanied transitions from syncopation to synchronization and followed the placement of the motor response within each stimulus/response cycle. Decomposition of event‐related fields into component auditory and motor brain responses revealed that the amplitude of the former decreased with increasing coordination rate whereas the motor contribution remained approximately constant across all rates. Such an interaction may contribute to changes in auditory‐motor integration that cause syncopation to become unstable. Examination of event‐related changes in high frequency bands revealed that MEG signal power in the beta band (15–30 Hz) was significantly lower during syncopated coordination in sensors covering the contralateral sensorimotor area suggesting a dependence of beta rhythm amplitude on task difficulty. Suppression of beta rhythms was also stronger during synchronization preceded by syncopation, e.g., after subjects had switched, when compared with a control condition in which subjects synchronized throughout the entire range of rates. Hum. Brain Mapping 14:65–80, 2001. © 2001 Wiley‐Liss, Inc.
A study on the selective phosphorylation and phosphinylation of hydroxyphenols
Authors: Marosi György , Toldy Andrea , Parlagh Gyula , Nagy Zoltán , Ludányi Krisztina , Anna Péter , Keglevich György 
Published: August 2002

AbstractBy choice of appropriate reaction conditions, the phosphorylation of hydroquinone by diethyl chlorophosphate gave predominantly the monophosphate (2). A similar reaction of phloroglucinol led to the mixture of the possible products (6, 7, and 8). The monophosphinylation of the above hydroxyphenols by diphenylphosphinyl chloride could be accomplished with a good selectivity to give product 4 or 9, the yields, however, being variable. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:126–130, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10006
Synthesis of new calix[4]arene‐based phosphorus ligands and their application in the Rh(I) catalyzed hydroformylation of 1‐octene
Authors: Kunze C. , Selent D. , Neda I. , Schmutzler R. , Spannenberg A. , Börner A. 
Published: August 2002

AbstractThe synthesis of calix[4]arene‐based phosphorus diamides and phosphites is described. These oligocyclic ligands have been tested in the Rh(I)‐ catalyzed hydroformylation of 1‐octene. Depending on the reaction conditions, yields up to 99% and n/iso‐selectivities between 0.7 and 2.6 have been observed. tert‐Butyl groups on the upper rim of the calix[4]arene template had a beneficial effect on the catalytic reaction. In general biuret‐derived P‐ligands were superior. For comparison, the corresponding “monomeric” ligands have also been synthesized and were employed in the catalytic reaction. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:577–585, 2001
Competitive [4 + 2] cycloadditions in equimolar mixtures of 1‐arylphosphole oxides
Authors: Keglevich György , Chuluunbaatar Tungalag , Dajka Beáta , Namkhainyambuu Bat‐Amgalan , Ludányi Krisztina , Tőke László 
Published: August 2002

AbstractFour different [4 + 2] cycloadditions were observed to take place in the equimolar mixtures of two different arylphosphole oxides 2a + 2b or 2b + 2c. In addition to the phosphole oxide dimers 3a‐a and 3b‐b, or 3b‐b and 3c‐c, the crossed cycloadducts 3a‐b and 3b‐a, or 3b‐c and 3c‐b were also formed in considerable portions. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:633–635, 2001
Transforming growth factor ß1 and ß2 (TGFβ2 / TGFβ2) profile changes in previously irradiated free flap beds
Authors: Schultze‐Mosgau Stefan , Wehrhan Falk , Grabenbauer Gerhard , Amann Kerstin , Radespiel‐Tröger Martin , Neukam Friedrich Wilhelm , Rodel Franz 
Published: August 2002

AbstractBackgroundFollowing preoperative radiotherapy prior to ablative surgery of squamous epithelial carcinomas of the head and neck region, inflammatory changes and the expression of cytokines involved in wound healing could be observed. These processes lead to a delayed healing of free flaps in the graft bed. The aim of the present experimental study was to analyze the expression profiles of transforming growth factor (activated TGFβ1, TGFβ2) and latency‐associated peptide (LAP) in the irradiated graft beds and the transition area between grafts and irradiated graft beds.MethodsIn Wistar rats (male, weight 300–500 g) undergoing preoperative irradiation of the neck region with 30 Gy (30 animals) and non‐irradiated rats (42 animals), a free myocutaneous gracilis flap taken from the groin was transplanted to the irradiated region of the neck. The interval between irradiation and transplantation was 4 weeks. In each group on postoperative days 3, 7, 14, and 28, cytoplasmatic expression of activated TGFβ1, LAP, and TGFβ2 was analyzed by immunohistochemistry to determine labeling indices (positive stained cells/total cells).ResultsThe success rate in graft beds irradiated with 30 Gy was 76% and in non‐irradiated graft beds was 86% (p = .02). In the graft beds irradiated with 30 Gy, there was an increased expression of activated TGFβ1 (range, 19.0–33.0), LAP (14.0–21.0), and TGFβ2 (3.0–19.5) together with obvious fibrosis. The expression was located in perivascular fibroblasts and endothelial cells. In contrast, a lower expression of activated TGFβ1 (11.0–21.0), LAP (1.0–8.0), and TGFβ2 (0.0–0.9) (p = .006) was observed in non‐irradiated graft beds. In the transition area between graft and irradiated graft bed, high expression of activated TGFβ1 (37.0), LAP (19.0), and TGFβ2 (16.7–33.4) was observed on the 3rd postoperative day in contrast to the transition area in non‐irradiated graft beds (activated TGFβ1 26.0, LAP 7.0, and TGFβ2 0.l).ConclusionThe radiation induced, increased de novo synthesis of LAP, activation of TGFβ1, and increased expression of TGFβ2 may represent at least one mechanism for the increased fibrosis and wound healing disorders seen in irradiated tissues and in the transition area to graft tissue. The expression of TGFβ1, LAP, and TGFβ2 might possess prognostic value with regard to wound healing and fibrosis in previously irradiated graft beds. © 2002 John Wiley & Sons, Inc. Head Neck 24: 33–41, 2002.
Quality of life and oral function in patients treated with radiation therapy for head and neck cancer
Authors: Epstein Joel B. , Robertson Manuella , Emerton Sue , Phillips Norm , Stevenson‐Moore Peter 
Published: August 2002

AbstractBackgroundMultiple oral complaints develop during radiation therapy for head and neck cancer, and quality of life is affected after treatment. The purpose of this investigation was to assess the quality of life, oral function, and oral symptoms in a cohort of patients during and after radiation therapy.MethodsA general quality of life survey (the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ‐C30), with an added oral symptom and function scale was administered to a consecutive series of patients who received radiation therapy for head and neck malignant disease. Patients completed surveys at the beginning of radiation therapy, immediately after, and 6 months after treatment.Results and DiscussionThe questionnaire used in this study provides increased information regarding the oral and dental function that is frequently affected by radiation therapy. Results of this study indicate the need to determine oral dysfunction after head and neck cancer therapy, so that the most predictable cure or best palliation of the malignancy with the least impact on oral function and quality of life is chosen.Oral complications during and after radiation therapy for head and neck cancer are common and affect quality of life. Oral QOL does not return to pretreatment levels by 6 months after radiation therapy. This study supports the use of a general function scale such as the EORTC questionnaire with the addition of disease/site‐specific scales to provide data on outcomes of therapy and on the complications associated with therapy. The EORTC QLQ 30 questionnaire with the oral assessment addendum provides a measure of the quality of life and oral function in head and neck cancer patients and may provide useful outcome measures for assessment of oral care prevention and management strategies in these patient populations. The results show that the questionnaire is responsive to change throughout the course of radiation therapy for head and neck cancer. © 2001 John Wiley & Sons, Inc. Head Neck 23: 389–398, 2001.
Significance and management of thyroid lesions in lymph nodes as an incidental finding during neck dissection
Authors: Fliegelman Lawrence J. , Genden Eric M. , Brandwein Margaret , Mechanick Jeffrey , Urken Mark L. 
Published: August 2002

AbstractBackgroundThe incidental discovery of thyroid lesions in lymph nodes during a lymph node dissection performed for a separate primary head and neck tumor is an unusual clinical entity. Its discovery has led to controversy regarding its significance and management.MethodsWe identified five patients over the years 1991–1999 with this finding. All five patients were subsequently treated with a total thyroidectomy and a level VI lymph node dissection.ResultsPathological examination revealed three papillary carcinomas and level VI lymph node metastases in the two patients who had carcinoma in their thyroid glands. All five patients are presently free of their primary and thyroid disease on follow‐up examinations.ConclusionsThese patients should be addressed with additional work‐up and surgery if metastatic thyroid cancer is documented in the lymph node. We offer a diagnostic algorithm that may aid in further work‐up and treatment in these unusual cases. © 2001 John Wiley & Sons, Inc. Head Neck 23: 885–891, 2001.
Differential mechanisms of Ca2+ responses in glial cells evoked by exogenous and endogenous glutamate in rat hippocampus
Authors: Latour Isabelle , Gee Christine E. , Robitaille Richard , Lacaille Jean‐Claude 
Published: August 2002

AbstractThe mechanisms of Ca2+ responses evoked in hippocampal glial cells in situ, by local application of glutamate and by synaptic activation, were studied in slices from juvenile rats using the membrane permeant fluorescent Ca2+ indicator fluo‐3AM and confocal microscopy. Ca2+ responses induced by local application of glutamate were unaffected by the sodium channel blocker tetrodotoxin and were therefore due to direct actions on glial cells. Glutamate‐evoked responses were significantly reduced by the L‐type Ca2+ channel blocker nimodipine, the group I/II metabotropic glutamate receptor antagonist (S)‐α‐methyl‐4‐carboxyphenylglycine (MCPG), and the N‐methyl‐D‐aspartate (NMDA) receptor antagonist (±)2‐amino‐5‐phosphonopentanoic acid (APV). However, glutamate‐induced Ca2+ responses were not significantly reduced by the non‐NMDA receptor antagonist 6‐cyano‐7‐nitro‐quinoxaline‐2,3‐dione (CNQX). These results indicate that local application of glutamate increases intracellular Ca2+ levels in glial cells via the activation of L‐type Ca2+ channels, NMDA receptors, and metabotropic glutamate receptors. Brief (1 s) tetanization of Schaffer collaterals produced increases in intracellular Ca2+ levels in glial cells that were dependent on the frequency of stimulation (≥50 Hz) and on synaptic transmission (abolished by tetrodotoxin). These Ca2+ responses were also antagonized by the L‐type Ca2+ channel blocker nimodipine and the metabotropic glutamate receptor antagonist MCPG. However, the non‐NMDA receptor antagonist CNQX significantly reduced the Schaffer collateral‐evoked Ca2+ responses, while the NMDA antagonist APV did not. Thus, these synaptically mediated Ca2+ responses in glial cells involve the activation of L‐type Ca2+ channels, group I/II metabotropic glutamate receptors, and non‐NMDA receptors. These findings indicate that increases in intracellular Ca2+ levels induced in glial cells by local glutamate application and by synaptic activity share similar mechanisms (activation of L‐type Ca2+ channels and group I/II metabotropic glutamate receptors) but also have distinct components (NMDA vs. non‐NMDA receptor activation, respectively). Therefore, neuron‐glia interactions in rat hippocampus in situ involve multiple, complex Ca2+‐mediated processes that may not be mimicked by local glutamate application. Hippocampus 2001;11:132–145. © 2001 Wiley‐Liss, Inc.
Fluid flow and heat transfer in the transition process of natural convection over an inclined plate
Authors: Komori Katsuo , Kito Shunsuke , Nakamura Toshihisa , Inaguma Yoshiaki , Inagaki Terumi 
Published: August 2002

AbstractThe present study deals with fluid flow and heat transfer in the transition process of natural convection over an inclined plate. In order to examine the mechanism of the transition process, experiments on the flow and heat transfer were performed for various plate inclination angles in the range of 20 to 75°. The wall temperature and fluid flow fields were visualized using a liquid crystal sheet and fluorescent paint, respectively. The visualization confirmed that separation of a boundary layer flow took place, and the onset point of streaks appeared over the plate wall when the modified Rayleigh number exceeded a characteristic value for each inclination angle. The local Nusselt number in the transition range was proportional to the one‐third power of the local modified Rayleigh number. By introducing a nondimensional parameter, a new correlation between visualizations of the flow and temperature fields and heat transfer was proposed. © 2001 Scripta Technica, Heat Trans Asian Res, 30(8): 648–659, 2001
Forced convective heat transfer for fluid flowing through a porous medium with internal heat generation
Authors: Du Hua , Wang Xuan 
Published: August 2002

AbstractForced convection in channels filled with packed beads with internal heat source was numerically analyzed by using the extended Darcy model for the flow and energy conservation equations with nonthermal equilibrium (NTE). The temperature difference between the matrix and fluid phases was discussed with three dimensionless parameters (Rep, H/dp, and ks/kf). It is concluded that the thermal equilibrium assumption may be adopted for the situation when the solid conduction dominated over the convection or when the heat transfer coefficient between the two phases is large at large Rep. The Nusselt number at the wall with the variation of Rep for different ks/kf was also investigated. © 2001 Scripta Technica, Heat Trans Asian Res, 30(3): 213–221, 2001
Spectral albedo/reflectance of littered forest snow during the melt season
Authors: Melloh Rae A. , Hardy Janet P. , Davis Robert E. , Robinson Peggy B. 
Published: August 2002

AbstractDespite the importance of litter on forest floor albedo and brightness, previous studies have not documented forest floor albedo or litter cover in any detail. Our objective was to describe the seasonal influence of litter on spectral albedos and nadir reflectances of a forest snowpack in a mixed‐hardwood stand in the Sleepers River Research Watershed (SRRW) in Danville, Vermont (37°39′ N, 119°2′ W). Experimental measurements in a nearby open area at the Snow Research Station of the SRRW nearly duplicated the spectral trend observed in the forest. Spectral albedo and nadir reflectance measurements in the visible and near infrared (350–2500 nm) transitioned from a gently curved shape through the visible range (for finer‐grained, lightly littered snow) to one having a peak in the red/near‐infrared (near 760 nm) as the snowmelt season progressed (for coarser‐grained, more heavily littered snow). The snowpack became optically thin as surface litter reached high percentages. A point‐in‐time digital photographic survey of the late‐lying snowpacks of three forest stands and the open showed that median litter cover percentages in the coniferous, deciduous, mixed‐forest, and an open area were 17·5, 6·1, 1·2, and 0·04 respectively. A Kruskal–Wallis ANOVA on ranks and pairwise comparisons using Dunn's test indicated that the litter covers of the three forest stands were significantly different with >95% confidence. The snowpack was relatively shallow (<1 m), as is typical for this area of Vermont. From a remote‐sensing standpoint, and since shallow snow and increased grain size also lower the visible albedo, we can expect that snowpack litter will cause decreased albedo earlier in the snowmelt season, at deeper snow depths, and will tend to shift the maximum albedo peak to the red/NIR range as the melt season progresses. Published in 2001 by John Wiley & Sons, Ltd.
Radio‐tracking gravel particles in a large braided river in New Zealand: a field test of the stochastic theory of bed load transport proposed by Einstein
Authors: Habersack H. M. 
Published: August 2002

AbstractHans A. Einstein initiated a probabilistic approach to modelling sediment transport in rivers. His formulae were based on theory and were stimulated by laboratory investigations. The theory assumes that bed load movement occurs in individual steps of rolling, sliding or saltation and rest periods. So far very few attempts have been made to measure stochastic elements in nature. For the first time this paper presents results of radio‐tracing the travel path of individual particles in a large braided gravel bed river: the Waimakariri River of New Zealand. As proposed by Einstein, it was found that rest periods can be modelled by an exponential distribution, but particle step lengths are better represented by a gamma distribution. Einstein assumed an average travel distance of 100 grain‐diameters for any bed load particle between consecutive points of deposition, but larger values of 6·7 m or 150 grain‐diameters and 6·1 m or 120 grain‐diameters were measured for two test particle sizes. Together with other available large scale field data, a dependence of the mean step length on particle diameter relative to the D50 of the bed surface was found. During small floods the time used for movement represents only 2·7% of the total time from erosion to deposition. The increase in percentage of time being used for transport means that it then has to be regarded in stochastic transport models. Tracing the flow path of bed load particles between erosion and deposition sites is a step towards explaining the interactions between sediment transport and river morphology. Copyright © 2001 John Wiley & Sons, Ltd.
Short‐term discharge and suspended sediment fluctuations in the proglacial Skeldal River, north‐east Greenland
Authors: Stott T. A. , Grove J. R. 
Published: August 2002

AbstractThe summer discharge pattern of the Skeldal River, which drains a 560 km2 partly glacierized catchment in north‐east Greenland, is dominated by diurnal oscillations reflecting variations in the melt rate of snow and ice in the basin. Superimposed on this diurnal pattern are numerous short‐lived discharge fluctuations of irregular periodicity and magnitude. The larger fluctuations are described and attributed to both rainfall events and periodic collapse of the glacier margin damming flow from beneath the Skelbrae glacier. Other minor fluctuations are less readily explained but are associated with changes in the channelized and distributed reservoirs and possibly temporary blockage of subglacial conduits caused by ice melt with subsequent damming.Fluctuations in suspended sediment concentration (SSC) are normally associated with discharge fluctuations, although examples of ‘transient flushes’ were observed where marked increases in SSC occurred in the absence of corresponding discharge variations. A strong relationship between the event discharge increase and event SSC increase for rainfall‐induced events was established, but no such relationship existed for non‐rainfall‐induced events. There is some evidence for an exhaustion effect in the SSC patterns both at the event time‐scale and as the month proceeds. A mean suspended sediment load of 1765 ± 0·26 t day−1 was estimated for the study period, which would be equivalent to a suspended sediment yield of 732 ± 4 t km−2 year−1. Copyright © 2001 John Wiley & Sons, Ltd.
Forest ecosystem processes at the watershed scale: hydrological and ecological controls of nitrogen export
Authors: Band L. E. , Tague C. L. , Groffman P. , Belt K. 
Published: August 2002

AbstractWe present a hierarchically distributed model of catchment forest hydrology and biogeochemistry. The goal of the model is to evaluate and predict the distribution of water, carbon and nitrogen cycling within a forested watershed, as well as the export of nitrate. We use a spatial hierarchy of land elements arranged through the stream network, and successively containing catchments, subcatchments, hillslopes, then patches (within each hillslope) to distribute key processes. Time scales of active processes range from those forced by daily meteorology to canopy growth and soil development occurring over decades. This allows us to follow the hydrological and biogeochemical dynamics of the landscape over a range of spatial and temporal scales. A key assumption of the model is that a substantial amount of the water movement through the unsaturated zone occurs as preferential flow. Nitrate is then transported downslope by rising saturated zones during storms. We test the predictions of the model with preliminary data generated as part of the Baltimore Long‐Term Ecological Research site. The hydrological modules of the model are calibrated with rainfall/runoff data from the 1980s, while the nitrogen cycling modules are uncalibrated. The model generated good correspondence to the seasonal dynamics of stream water nitrate concentration over the 1998–1999 water year. Copyright © 2001 John Wiley & Sons, Ltd.