bluuebunny/crossref_metadata_2025 huggingface dataset:
Microdevices for manipulation and accumulation of micro‐ and nanoparticles by dielectrophoresis
Authors: Dürr Manfried , Kentsch Jörg , Müller Torsten , Schnelle Thomas , Stelzle Martin
Published: February 2003

Microfluidic devices with three‐dimensional (3‐D) arrays of microelectrodes embedded in microchannels have been developed to study dielectrophoretic forces acting on synthetic micro‐ and nanoparticles. In particular, so‐called deflector structures were used to separate particles according to their size and to enable accumulation of a fraction of interest into a small sample volume for further analysis. Particle velocity within the microchannels was measured by video microscopy and the hydrodynamic friction forces exerted on deflected particles were determined according to Stokes law. These results lead to an absolute measure of the dielectrophoretic forces and allowed for a quantitative test of the underlying theory. In summary, the influence of channel height, particle size, buffer composition, electric field, strength and frequency on the dielectrophoretic force and the effectiveness of dielectrophoretic deflection structures were determined. For this purpose, microfluidic devices have been developed comprising pairs of electrodes extending into fluid channels on both top and bottom side of the microfluidic channels. Electrodes were aligned under angles varying from 0 to 75° with respect to the direction of flow. Devices with channel height varying between 5 and 50 μm were manufactured. Fabrication involved a dedicated bonding technology using a mask aligner and UV‐curing adhesive. Particles with radius ranging from 250 nm to 12 μm were injected into the channels using aqueous buffer solutions.
In‐column field‐amplified sample stacking of biogenic amines on microfabricated electrophoresis devices
Authors: Beard Nigel P. , Zhang Chao‐Xuan , deMello Andrew J.
Published: February 2003

A novel method for performing in‐column field‐amplified sample stacking (FASS) in chip‐based electrophoretic systems is presented. The methodology involves the use of a narrow sample channel (NSC) injector. NSC injectors allow sample plugs to be introduced directly into the separation channel, and subsequent stacking and separation can proceed without any need for leakage control. More importantly, stacking and separation occur in a single step negating the requirement for complex channel geometries and voltage switching to control sample plugs during the stacking procedure. The chip is composed of six paralleled systems. Using the NSC injector design, the number of reservoirs in the multiplexed chip is reduced to N + 2, where N is the number of paralleled systems. This design feature radically reduces the complexity in chip structures and associated chip operation. The approach is applied to the analysis of fluorescently labelled biogenic amines affording detection at concentrations down to 20 pM.
Analysis of the quorum‐sensing regulon of the opportunistic pathogen Burkholderia cepacia H111 by proteomics
Authors: Riedel Kathrin , Arevalo‐Ferro Catalina , Reil Gerold , Görg Angelika , Lottspeich Friedrich , Eberl Leo
Published: February 2003

Burkholderia cepacia H111, an important pathogen for persons suffering from cystic fibrosis, employs a quorum‐sensing (QS) system, cep, to control expression of virulence factors as well as the formation of biofilms. The QS system is thought to ensure that pathogenic traits are only expressed when the bacterial population density is high enough to overwhelm the host before it is able to mount an efficient response. In this study, we compared the protein pattern of the intracellular, extracellular, and surface protein fractions of an AHL‐deficient cepI mutant with the one of the parent strain H111 by means of two‐dimensional gel electrophoresis (2‐DE). Our analysis showed that 55 proteins out of 985 detected spots were differentially expressed; these are expected to represent QS‐controlled gene products. Addition of the respective signal molecules to the growth medium of the cep mutant fully restored the wild‐type protein expression profile. In total about 5% of the B. cepacia proteome was downregulated and 1% upregulated in the cepI mutant, indicating that quorum sensing represents a global regulatory system. Nineteen proteins were identified with high confidence by N‐terminal sequence analysis.
Sodium dodecyl sulfate versus acid‐labile surfactant gel electrophoresis: Comparative proteomic studies on rat retina and mouse brain
Authors: König Simone , Schmidt Oliver , Rose Karin , Thanos Solon , Besselmann Michael , Zeller Martin
Published: February 2003

A long‐chain derivative of 1,3‐dioxolane sodium propyloxy sulfate, with similar denaturing and electrophoretic properties as SDS, and facilitated protein identification following polyacrylamide gel electrophoresis (PAGE) for Coomassie‐stained protein bands, has been tested. Comparative acid‐labile surfactant/sodium dodecyl sulfate two‐dimensional (ALS/SDS 2‐D)‐PAGE experiments of lower abundant proteins from the proteomes of regenerating rat retina and mouse brain show that peptide recovery for mass spectrometry (MS) mapping is significantly enhanced using ALS leading to more successful database searches. ALS may influence some procedures in proteomic analysis such as the determination of protein content and methods need to be adjusted to that effect. The promising results of the use of ALS in bioanalytics call for detailed physicochemical investigations of surfactant properties.
Multiple polypeptide forms observed in two‐dimensional gels of Methylococcus capsulatus (Bath) polypeptides are generated during the separation procedure
Authors: Berven Frode S. , Karlsen Odd A. , Murrell J. Colin , Jensen Harald B.
Published: February 2003

We have examined two‐dimensional electrophoresis (2‐DE) gel maps of polypeptides from the Gram‐negative bacterium Methylococcus capsulatus (Bath) and found the same widespread trains of spots as often reported in 2‐DE gels of polypeptides of other Gram‐negative bacteria. Some of the trains of polypeptides, both from the outer membrane and soluble protein fraction, were shown to be generated during the separation procedure of 2‐DE, and not by covalent post‐translational modifications. The trains were found to be regenerated when rerunning individual polypeptide spots. The polypeptides analysed giving this type of trains were all found to be classified as stable polypeptides according to the instability index of Guruprasad et al. (Protein Eng. 1990, 4, 155–161). The phenomenon most likely reflects conformational equilibria of polypeptides arising from the experimental conditions used, and is a clear drawback of the standard 2‐DE procedure, making the gel picture unnecessarily complex to analyse.
The use of dynamic grid adaptation algorithms for the modelling of flow around a circular cylinder in sub‐critical flow regime
Authors: de With G. , Holdø A. E. , Huld T. A.
Published: February 2003

In the present study a dynamic grid adaptation (DGA) algorithm is utilized for predicting flow around a circular cylinder in sub‐critical flow regime at a Reynolds number of 1.4×105. The reason for adopting a DGA algorithm is the unsteadiness of the flow field which makes a conventional mesh inefficient. The concept being adopted is to concentrate mesh refinement in regions with high gradients and high turbulent viscosity, while in the region further downstream where the flow is fully developed a coarser mesh will develop and turbulence is modelled with the large eddy simulation (LES) turbulence model.

The aim of the study is to present an appropriate variable for mesh refinement, which accomplishes a high rate of mesh refinement in the region with high gradients. The new variable is a product of the local mesh cell size and the rate of strain and includes two additional variables to allow control over the refinement behaviour. The results are compared with experimental data at the corresponding Reynolds number and also with numerical results obtained with conventional mesh. It is demonstrated that DGA algorithms can give results of a very high quality for a mesh that is significantly smaller than for a conventional mesh. Copyright © 2003 John Wiley & Sons, Ltd.
Parallel finite element simulation of mooring forces on floating objects
Authors: Aliabadi S. , Abedi J. , Zellars B.
Published: February 2003

The coupling between the equations governing the free‐surface flows, the six degrees of freedom non‐linear rigid body dynamics, the linear elasticity equations for mesh‐moving and the cables has resulted in a fluid‐structure interaction technology capable of simulating mooring forces on floating objects. The finite element solution strategy is based on a combination approach derived from fixed‐mesh and moving‐mesh techniques. Here, the free‐surface flow simulations are based on the Navier–Stokes equations written for two incompressible fluids where the impact of one fluid on the other one is extremely small. An interface function with two distinct values is used to locate the position of the free‐surface. The stabilized finite element formulations are written and integrated in an arbitrary Lagrangian–Eulerian domain. This allows us to handle the motion of the time dependent geometries. Forces and momentums exerted on the floating object by both water and hawsers are calculated and used to update the position of the floating object in time. In the mesh moving scheme, we assume that the computational domain is made of elastic materials. The linear elasticity equations are solved to obtain the displacements for each computational node. The non‐linear rigid body dynamics equations are coupled with the governing equations of fluid flow and are solved simultaneously to update the position of the floating object. The numerical examples includes a 3D simulation of water waves impacting on a moored floating box and a model boat and simulation of floating object under water constrained with a cable. Copyright © 2003 John Wiley & Sons, Ltd.
Rotary oscillations of axi‐symmetric bodies in an axi‐symmetric viscous flow with slip: Numerical solutions for sphere and spheroids
Authors: Tekasakul P. , Loyalka S. K.
Published: February 2003

Rotary oscillations of several axi‐symmetric bodies in axi‐symmetric viscous flows with slip are investigated. A numerical method based on the Green's function technique is used wherein the relevant Helmholtz equation, as obtained from the unsteady Stokes equation, is converted into a surface integral equation. The technique is benchmarked against a known analytical solution, and accurate numerical results for local stress and torque on spheres and spheroids as function of the frequency parameter and the slip coefficients are obtained. It is found that in all cases, slip reduces stress and torque, and increasingly so with the increasing frequency parameter. The method discussed here can be potentially extended to the realistic case of an oscillating disk viscometer. Copyright © 2003 John Wiley & Sons, Ltd.
Central schemes for open‐channel flow
Authors: Gottardi Guido , Venutelli Maurizio
Published: February 2003

The resolution of the Saint‐Venant equations for modelling shock phenomena in open‐channel flow by using the second‐order central schemes of Nessyahu and Tadmor (NT) and Kurganov and Tadmor (KT) is presented. The performances of the two schemes that we have extended to the non‐homogeneous case and that of the classical first‐order Lax–Friedrichs (LF) scheme in predicting dam‐break and hydraulic jumps in rectangular open channels are investigated on the basis of different numerical and physical conditions. The efficiency and robustness of the schemes are tested by comparing model results with analytical or experimental solutions. Copyright © 2003 John Wiley & Sons, Ltd.
Validations of CFD against detailed velocity and pressure measurements in water turbine runner flow
Authors: Nilsson H. , Davidson L.
Published: February 2003

This work compares CFD results with experimental results of the flow in two different kinds of water turbine runners. The runners studied are the GAMM Francis runner and the Hölleforsen Kaplan runner. The GAMM Francis runner was used as a test case in the 1989 GAMM Workshop on 3D Computation of Incompressible Internal Flows where the geometry and detailed best efficiency measurements were made available. In addition to the best efficiency measurements, four off‐design operating condition measurements are used for the comparisons in this work. The Hölleforsen Kaplan runner was used at the 1999 Turbine 99 and 2001 Turbine 99—II workshops on draft tube flow, where detailed measurements made after the runner were used as inlet boundary conditions for the draft tube computations. The measurements are used here to validate computations of the flow in the runner.

The computations are made in a single runner blade passage where the inlet boundary conditions are obtained from an extrapolation of detailed measurements (GAMM) or from separate guide vane computations (Hölleforsen). The steady flow in a rotating co‐ordinate system is computed. The effects of turbulence are modelled by a low‐Reynolds number k‐ω turbulence model, which removes some of the assumptions of the commonly used wall function approach and brings the computations one step further.

The computational results are compared to the measurements with respect to detailed velocity and pressure distributions at several measurement sections and several operating conditions. The computational results are also compared to coarse grid wall function computations by the TASCflow CFD code, which uses a similar methodology as the CALC‐PMB CFD code used in the present work. The comparisons show where the computational method is sufficient and where it is not sufficient.The behaviour of the computational method is similar for both kinds of water turbines, which shows that experience of computations in water turbines will ultimately give quantitatively correct results. Copyright © 2003 John Wiley & Sons, Ltd.
A new positive‐definite regularization of incompressible Navier–Stokes equations discretized with Q1/P0 finite element
Authors: Eguchi Yuzuru
Published: February 2003

A new regularization method is proposed for the Galerkin approximation of the incompressible Navier–Stokes equations with Q1/P0 element, by newly introducing a square‐type linear form into the variational divergence‐free constraint regularized with the global pressure jump (GPJ) method. The addition of the square‐type linear form is intended to eliminate the hydrostatic pressure mode appearing in confined flows, and to make the discretized matrix positive definite and then non‐singular without the pressure pegging trick. Effects of the free parameters for the regularization on the solutions are numerically examined with a 2‐D driven cavity flow problem. Furthermore, the convergences in the conjugate gradient iteration for the solution of the pressure Poisson equation are compared among the mixed method, the GPJ method and the present method for both leaky and non‐leaky 3‐D driven cavity flows. Finally, the non‐leaky 3‐D cavity flows at different Re numbers are solved to compare with the literature data and to demonstrate the accuracy of the proposed method. Copyright © 2003 John Wiley & Sons, Ltd.
Option volume and volatility response to scheduled economic news releases
Authors: Nofsinger John R. , Prucyk Brian
Published: February 2003

In this article, we examine the impact of 21 different types of scheduled macroeconomic news announcements on
S&P 100 stock‐index option volume and implied volatility. We find that there is a 2‐h delay
after the announcement before volume increases. However, there is an immediate increase in volatility, which
slowly dissipates over several hours. Further analysis shows that most of the high volume and volatility after
announcements come from the announcements that are considered bad news. That is, bad news creates high
volatility and high volume, whereas good news elicits lower volume and is not associated with higher volatility.
These results are not consistent with the predictions of any one model. We also find that the announcements that
cause the largest reaction in the equity option market are Consumer Credit, Consumer Spending, Factory
Inventories, NAPM, and Non‐Farm Payrolls. Six other announcements elicit a mild response. © 2003
Wiley Periodicals, Inc. Jrl Fut Mark 23:315–345, 2003
The components of interest rate swap spreads: Theory and international evidence
Authors: Fehle Frank
Published: February 2003

This article contains both a theoretical and an empirical analysis of the components of interest rate swap
spreads defined as the difference between the fixed swap rate and the risk‐free rate of equal maturity.
The components are determined by expected LIBOR spreads, default risk, and market structure. A model of the swap
market incorporating debt market imperfections and corporate financing choices is used to explain participation
by both swap buyers and sellers. The model also motivates an empirical relationship between swap spreads and the
slope of the risk‐free term structure. The article then provides empirical evidence on the
cross‐sectional and time‐series variation of swap spreads in seven international markets. The
evidence is consistent with the suggested components across both markets and swap maturities as well as over
time. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:347–387, 2003
Volatility and trading demands in stock index futures
Authors: Pan Ming‐Shiun , Liu Y. Angela , Roth Herbert J.
Published: February 2003

In this study we examine how volatility and the futures risk premium affect trading demands for hedging and
speculation in the S&P 500 Stock Index futures contracts. To ascertain if different volatility measures matter
in affecting the result, we employ three volatility estimates. Our empirical results show a positive relation
between volatility and open interest for both hedgers and speculators, suggesting that an increase in volatility
motivates both hedgers and speculators to engage in more trading in futures markets. However, the influence of
volatility on futures trading, especially for hedging, is statistically significant only when spot volatility is
used. We also find that the demand to trade by speculators is more sensitive to changes in the futures risk
premium than is the demand to trade by hedgers. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:399–414,
2003
Futures hedging under mark‐to‐market risk
Authors: Lien Donald , Li Anlong
Published: February 2003

This article introduces mark‐to‐market risk into the conventional futures hedging framework. It
is shown that a hedger concerned with maximum daily loss will considerably reduce his futures position when the
risk is taken into account. In case of a moderate hedge horizon, the hedger will hedge approximately 80% of
his spot position.

The effect of mark‐to‐market risk decreases very slowly as the hedge horizon increases. If the
hedger is concerned with average daily loss, the effect is minimal for a moderate hedge horizon. © 2003 Wiley
Periodicals, Inc. Jrl Fut Mark 23:389–398, 2003
Geophysical exploration of Guajará, a prehistoric earth mound in Brazil
Authors: Bevan Bruce W. , Roosevelt Anna C.
Published: February 2003

An interdisciplinary team studied Guajará, a prehistoric artificial mound in the Brazilian Amazon. The geophysical surveys and excavations were interactive;this interaction furnished more information than either geophysics or excavation alone could have provided. While seven different geophysical methods were applied, the magnetic survey reported here was particularly valuable. A detailed interpretation of this survey quantified the magnetic material in the mound, and this furnished an initial estimate of the number of cooking hearths in the mound. Ten test excavations were concentrated at magnetic anomalies. These excavations located cooking hearths and burial urns. A reevaluation of the magnetic survey was then done in order to refine the estimate of the number of hearths in the mound; this yielded an estimate of 2200 hearths. This allowed the population of the site to be approximated at 78–156 people. The geophysical survey and excavations also identified possible locations for subsequent broad‐area excavations. © 2003 Wiley Periodicals, Inc.
Short contribution: Nile flow failure at the end of the Old Kingdom, Egypt: Strontium isotopic and petrologic evidence
Authors: Stanley Jean‐Daniel , Krom Michael D. , Cliff Robert A. , Woodward Jamie C.
Published: February 2003

Strontium isotopic and petrologic information, obtained from sediment cores collected in the Nile delta of Egypt, indicate that paleoclimatic and Nile baseflow conditions changed considerably from about 4200 to 4000 cal yr B.P. in the Nile basin. Our study records a higher proportion of White Nile sediment transported during the annual floods at ca. 6100 cal yr B.P. than towards 4200 cal yr B.P., at which time suspended sediment from the Blue Nile formed a significantly larger fraction of the total load. This resulted from a decrease in vegetative cover and an increase in erosion rate accompanying the marked decline in rainfall. These new geoscience data indicate major changes in annual flooding and baseflow of the river Nile, marked short‐term paleoclimatic‐related events that may in part have led to the collapse of the Old Kingdom. © 2003 Wiley Periodicals, Inc.
A 3.5 ka record of paleoenvironments and human occupation at Angkor Borei, Mekong Delta, southern Cambodia
Authors: Bishop Paul , Penny Dan , Stark Miriam , Scott Marian
Published: February 2003

Microfossil and sedimentological data from a 3.1 m core extracted from a reservoir (baray) at the ancient Cambodian settlement of Angkor Borei in the Mekong Delta have provided a continuous record of sedimentation and paleoenvironments dating from about 2000 cal yr B.C. Palynological data indicate that for much of the cal. 1st and 2nd millennia B.C. mangroves dominated the regional vegetation, while extensively and regularly burnt grasslands dominated the local vegetation. Turbid, nutrient‐rich standing water characterized the core locality, perhaps suggesting a connection with rivers in the area. An abrupt change during the cal. 5th to 6th centuries A.D. involved a dramatic reduction in grasslands and the expansion of secondary forest or re‐growth taxa. These changes are synchronous with an abrupt decline in the concentration of microscopic charcoal particles in the sediments, and the colonization of the core locality by swamp forest plants. These changes are taken to indicate a shift in land‐use strategies or, possibly, a period of land abandonment. The age for the construction of the baray is interpreted to be in the 17th–19th centuries, but this dating remains speculative. Construction of the Angkor Borei baray exploited a preexisting body of standing water, so its construction was fundamentally different from the methods used at the Angkorian capital in northern Cambodia. © 2003 Wiley Periodicals, Inc.
Geothermal activity at the archaeological site of Aghia Kyriaki and its significance to Roman industrial mineral exploitation on Melos, Greece
Authors: Hall A. J. , Photos‐Jones E. , McNulty A. , Turner D. , McRobb A.
Published: February 2003

The geothermal setting of the archaeological site at Aghia Kyriaki, Southeast Melos (or Milos) was investigated in order to help clarify the possible role of the site in mineral exploitation on Melos in Roman times. There are active sulfurous fumaroles in the area and these were also potential sources of sulfur and alum‐group minerals in Roman times. However, geothermal activity has been ongoing in Southeast Melos for hundreds of thousands of years, and extensive hydrothermal alteration of basement rocks to the northeast of the site has produced “white rocks” containing additional potential industrial minerals such as kaolin and alunite. The archaeological remains occur within, but mainly near the surface, of a deeply gullied sequence of late Quaternary alluvial sediments, which consist mainly of metamorphic detritus but are rich in sulfates; the remains contain pottery sherds through the entire sequence of about 40 m. They were deposited on an earlier gullied topography of felsic tuffs overlying the metamorphic basement. Pervasive and veinlike intense reddish alteration of these sediments is probably mainly due to superheated fluid escaping from depth. Field observations demonstrate that this took place after the main phase of building but was likely to be ongoing during occupation of the site. While industrial minerals and geothermal energy would therefore have been available in the Roman period, any relationship of the site to mineral exploitation will have to be determined by archaeological excavation. © 2003 Wiley Periodicals, Inc.
A cross‐linguistic fMRI study of perception of intonation and emotion in Chinese
Authors: Gandour Jack , Wong Donald , Dzemidzic Mario , Lowe Mark , Tong Yunxia , Li Xiaojian
Published: February 2003

Conflicting data from neurobehavioral studies of the perception of intonation (linguistic) and emotion (affective) in spoken language highlight the need to further examine how functional attributes of prosodic stimuli are related to hemispheric differences in processing capacity. Because of similarities in their acoustic profiles, intonation and emotion permit us to assess to what extent hemispheric lateralization of speech prosody depends on functional instead of acoustical properties. To examine how the brain processes linguistic and affective prosody, an fMRI study was conducted using Chinese, a tone language in which both intonation and emotion may be signaled prosodically, in addition to lexical tones. Ten Chinese and 10 English subjects were asked to perform discrimination judgments of intonation (I: statement, question) and emotion (E: happy, angry, sad) presented in semantically neutral Chinese sentences. A baseline task required passive listening to the same speech stimuli (S). In direct between‐group comparisons, the Chinese group showed left‐sided frontoparietal activation for both intonation (I vs. S) and emotion (E vs. S) relative to baseline. When comparing intonation relative to emotion (I vs. E), the Chinese group demonstrated prefrontal activation bilaterally; parietal activation in the left hemisphere only. The reverse comparison (E vs. I), on the other hand, revealed that activation occurred in anterior and posterior prefrontal regions of the right hemisphere only. These findings show that some aspects of perceptual processing of emotion are dissociable from intonation, and, moreover, that they are mediated by the right hemisphere. Hum. Brain Mapping 18:149–157, 2003. © 2003 Wiley‐Liss, Inc.
Neural systems of second language reading are shaped by native language
Authors: Tan Li Hai , Spinks John A. , Feng Ching‐Mei , Siok Wai Ting , Perfetti Charles A. , Xiong Jinhu , Fox Peter T. , Gao Jia‐Hong
Published: February 2003

Reading in a second language (L2) is a complex task that entails an interaction between L2 and the native language (L1). To study the underlying mechanisms, we used functional magnetic resonance imaging (fMRI) to visualize Chinese–English bilinguals' brain activity in phonological processing of logographic Chinese and alphabetic English, two written languages with a sharp contrast in phonology and orthography. In Experiment 1, we found that phonological processing of Chinese characters recruits a neural system involving left middle frontal and posterior parietal gyri, cortical regions that are known to contribute to spatial information representation, spatial working memory, and coordination of cognitive resources as a central executive system. We assume that the peak activation of this system is relevant to the unique feature of Chinese that a logographic character has a square configuration that maps onto a monosyllabic unit of speech. Equally important, when our bilingual subjects performed a phonological task on English words, this neural system was most active, whereas brain areas mediating English monolinguals' fine‐grained phonemic analysis, as demonstrated by Experiment 2, were only weakly activated. This suggests that our bilingual subjects were applying their L1 system to L2 reading and that the lack of letter‐to‐sound conversion rules in Chinese led Chinese readers to being less capable of processing English by recourse to an analytic reading system on which English monolinguals rely. Our brain imaging findings lend strongest support to the idea that language experience tunes the cortex. Hum. Brain Mapping 18:158–166, 2003. © 2003 Wiley‐Liss, Inc.
The time course of brain activity in reading English and Chinese: An ERP study of Chinese bilinguals
Authors: Liu Ying , Perfetti Charles A.
Published: February 2003

Chinese bilinguals performed a delayed naming task, reading both Chinese characters and English words, while EEGs were recorded by a 128‐channel system. Principle component analysis (PCA) of Event Related Potentials (ERP) from the onset of the stimulus suggested a temporal unfolding of graphic, phonological, and semantic processing that depended on both language and word frequency. At 150 msec, Chinese produced an earlier and higher amplitude shift (N150) than English. At 250 msec, frequency effects were significant for both Chinese and English, but at 450 msec, only the English frequency effect was reliable. Source localization analysis by Low Resolution Electromagnetic Tomography (LORETA) showed bilateral occipital (left BA 17, right BA 18) visual processing of Chinese characters with left occipital only (left BA 17) for English high‐frequency words. Low‐frequency English words showed activation bilaterally, but with a more diffused and extended temporal pattern. Right prefrontal area (BA 10) was found to be strongly activated in the mid latency (300–400 msec) period of Chinese character naming, whereas English word naming showed more medial frontal (BA 8, and 10) activation. A post 450‐msec visual verification was found to be general for both writing systems. Hum. Brain Mapping 18:167–175, 2003. © 2003 Wiley‐Liss, Inc.
Developmental aspects of language processing: fMRI of verbal fluency in children and adults
Authors: Gaillard William D. , Sachs Bonnie C. , Whitnah Joseph R. , Ahmad Zaaira , Balsamo Lyn M. , Petrella Jeffrey R. , Braniecki Suzanne H. , McKinney Christopher M. , Hunter Kevin , Xu Ben , Grandin Cecile B.
Published: February 2003

We examined developmental differences, in location and extent of fMRI language activation maps, between adults and children while performing a semantic fluency task. We studied 29 adults and 16 children with echo planar imaging BOLD fMRI at 1.5 T using covert semantic verbal fluency (generation of words to categories compared to rest) using a block design. Post task testing was administered to assess performance. Individual data were analyzed with an a priori region of interest approach from t maps (t = 4) and asymmetry indices (AI). Group studies were analyzed using SPM 99 (Wellcome, UK; fixed effect, corrected P < 0.0001). We found no significant differences in location or laterality of activation between adults and children for a semantic verbal fluency task. Adults activated more pixels than children in left inferior frontal gyrus and left middle frontal gyrus, but AIs were the similar across ages (r2 < 0.09). Extent or laterality of activation was not affected by performance (r2 < 0.15). The brain areas that process semantic verbal fluency are similar in children and adults. The laterality of activation does not change appreciably with age and appears to be strongly lateralized by age 7 years. Hum. Brain Mapping 18:176–185, 2003. © 2003 Wiley‐Liss, Inc. Published 2003 Wiley‐Liss, Inc.
Comparison of block and event‐related fMRI designs in evaluating the word‐frequency effect
Authors: Chee Michael W.L. , Venkatraman Vinod , Westphal Christopher , Siong Soon Chun
Published: February 2003

Printed word frequency can modulate retrieval effort in a task requiring associative semantic judgment. Event‐related fMRI, while avoiding stimulus order predictability, is in theory statistically less powerful than block designs. We compared one event‐related and two block designs that evaluated the same semantic judgment task and found that similar brain regions demonstrated the word frequency effect. Although the responses were lower in amplitude, event‐related fMRI was able to detect the word frequency effect to a comparable degree compared to the block designs. The detection of a frequency effect with the event‐related design also suggests that stimulus–order predictability may not be as serious a concern in block designs as might be supposed. Hum. Brain Mapping 18:186–193, 2003. © 2003 Wiley‐Liss, Inc.
Bilateral brain abnormalities associated with dominantly inherited verbal and orofacial dyspraxia
Authors: Belton Emma , Salmond Claire H. , Watkins Kate E. , Vargha‐Khadem Faraneh , Gadian David G.
Published: February 2003

The KE family is a large three‐generational pedigree in which half of the members suffer from a verbal and orofacial dyspraxia in association with a point mutation in the FOXP2 gene. This report extends previous voxel‐based morphometric analyses of magnetic resonance imaging (MRI) scans (Watkins et al. [2002] Brain 125:465–478) using a bilateral conjunction analysis. This searches specifically for areas of grey matter density that differ bilaterally in the affected members compared with both matched controls and the unaffected family members. 3‐D T1‐weighted MRI datasets of 17 family members (10 affected, 7 unaffected) and matched controls were compared. The most significant findings were reduced grey matter density bilaterally in the caudate nucleus, the cerebellum, and the left and right inferior frontal gyrus in the affected members. In addition, increased grey matter density was found bilaterally in the planum temporale. These results confirm that a point mutation in FOXP2 is associated with several bilateral grey matter abnormalities in both motor and language related regions. The results also demonstrate the advantages of using a conjunction analysis when bilateral abnormalities are suspected. Hum. Brain Mapping 18:194–200, 2003. © 2003 Wiley‐Liss, Inc.
Distinct brain regions associated with syllable and phoneme
Authors: Siok Wai Ting , Jin Zhen , Fletcher Paul , Tan Li Hai
Published: February 2003

The syllable and the phoneme are two important units in the phonological structure of speech sounds. In the brain mapping literature, it remains unsolved as to whether there are separate brain regions mediating the processing of syllables and phonemes. Using functional magnetic resonance imaging (fMRI), we investigated the neural substrate of these phonological units with Chinese subjects. Results revealed that the left middle frontal cortex contributes to syllabic processing, whereas the left inferior prefrontal gyri contributes to phonemic processing. This pattern of findings offers compelling evidence for distinct cortical areas relevant to the representation of syllables and phonemes. Hum. Brain Mapping 18:201–207, 2003. © 2003 Wiley‐Liss, Inc.
Involvement of the cerebellum in semantic discrimination: An fMRI study
Authors: Xiang Huadong , Lin Chongyu , Ma Xiaohai , Zhang Zhaoqi , Bower James M. , Weng Xuchu , Gao Jia‐Hong
Published: February 2003

We investigated, using functional magnetic resonance imaging (fMRI), whether semantic discrimination, an inner linguistic task without overt articulation, can elicit activation in the cerebellum. Six subjects performed three semantic tasks with different loads of discrimination while being scanned. All three semantic tasks activated distributed brain areas, including the right posterior inferior cerebellum. Much stronger activation was found in the cerebellum in more difficult tasks, in terms of the activation volume and signal intensity. These results suggest that the cerebellum activation is involved in semantic discrimination and is modulated by discrimination difficulty. Hum. Brain Mapping 18:208–214, 2003. © 2003 Wiley‐Liss, Inc.
Neural basis of the non‐attentional processing of briefly presented words
Authors: Peng Dan‐ling , Xu Duo , Jin Zhen , Luo Qian , Ding Guo‐sheng , Perry Conrad , Zhang Lei , Liu Ying
Published: February 2003

The neural basis of the automatic activation of words was investigated in an fMRI study. In the study, words were presented briefly (51 or 151 msec) followed by a mask. To prevent attentional processing, subjects attended to the masks and not the words, and were required to make perceptual judgment about the masks. We found that a distributed neural network (including the frontal, temporal, occipital, parietal lobes, and the cerebellum) was activated during non‐attentional processing of words in both exposure durations. A significant main effect of presentation duration was found in bilateral cerebellum and the right fusiform gyrus, suggesting their role in the later (151 msec) processing of words. In addition, a significant interaction between presentation duration and word frequency was obtained. When the presentation duration was 151 msec, no significant difference in activation was found between high‐ and low‐frequency words. Alternatively, when the presentation duration was 51 msec, high‐frequency words evoked significantly greater activation in bilateral fusiform gyri, cerebellum, right inferior parietal lobe, medial frontal gyrus (BA 45/46/9), and the right temporal‐occipital junction (BA 21/37). These results suggest that these regions are sensitive to word frequency, and are related to both the attentional and non‐attentional access of lexical representations. Hum. Brain Mapping 18:215–221, 2003. © 2003 Wiley‐Liss, Inc.
Modulation of neural connectivity during tongue movement and reading
Authors: He Alex G. , Tan Li Hai , Tang Yiyuan , James G. Andrew , Wright Paul , Eckert Mark A. , Fox Peter T. , Liu Yijun
Published: February 2003

In a functional magnetic resonance imaging (fMRI) study, a novel connectivity analysis method termed within‐condition interregional covariance analysis (WICA) was introduced for investigation into brain modulation during tongue movement and reading Chinese pinyins and logographic characters. We found that performing a horizontal tongue movement task generated a specific brain module with hierarchical orders of neural computation. Such functional modularity was further examined during both overt and silent Chinese reading tasks. Our results showed that overt pinyin reading was associated with the following distributed regions involved in tongue movement: the primary motor cortex (M1), the supplementary motor area (SMA), Broca's area, and Wernicke's area. Furthermore, we have used the WICA and demonstrated task‐dependent covariance patterns that are strongly associated with the M1 mouth/tongue region, in which the Broca‐Wernicke pathway is implicated in a meaning access procedure based on assembled phonology, while the SMA‐Broca pathway is implicated in a meaning access procedure based on addressed phonology. Our functional connectivity analysis of the neural pathway involved in language processing may provide a basis for future studies of the dynamic neural network associated with language learning and reading in both developmental and disease conditions. Hum. Brain Mapping 18:222–232, 2003. © 2003 Wiley‐Liss, Inc.
An fMRI study comparing brain activation between word generation and electrical stimulation of language‐implicated acupoints
Authors: Li Geng , Liu Ho‐Ling , Cheung Raymond T.F. , Hung Yu‐Chiang , Wong Kelvin K.K. , Shen Gary G.X. , Ma Qi‐Yuan , Yang Edward S.
Published: February 2003

We compared the brain activation on functional magnetic resonance imaging (MRI) during word generation with the activation during electrical stimulation of two language‐implicated acupoints in 17 healthy, Mandarin‐speaking, Chinese male volunteers (age 19–26 years). All subjects were strongly right handed according to a handedness inventory. Using a standard functional MRI procedure and a word‐generation paradigm, significant activation was seen in the left and right inferior frontal gyri (BA 44, 45) as well as the left superior temporal gyrus (BA 22, 42). Stronger activation with a larger volume was seen in the left hemisphere. Electrical stimulation of either one of the two language‐implicated acupoints, SJ 8 (11 subjects) and Du 15 (6 subjects), without the word‐generation paradigm in the same cohort, produced significant activation in the right inferior frontal gyrus (BA 44, 46) and in the left and right superior temporal gyri (BA 22, 42), respectively. Nevertheless, no activation was seen in the left inferior frontal gyrus. In addition, electrical stimulation of the adjacent non‐acupoints did not produce any significant brain activation. Although our results support the notion of acupoint–brain activation, applying acupuncture at SJ 8 or Du 15 does not activate the typical language areas in the left inferior frontal cortex. Hum. Brain Mapping 18:233–238, 2003. © 2003 Wiley‐Liss, Inc.
Towards understanding language organisation in the brain using fMRI
Authors: Matthews P. M. , Adcock J. , Chen Y. , Fu S. , Devlin J. T. , Rushworth M. F. S. , Smith S. , Beckmann C. , Iversen S.
Published: February 2003

Functional magnetic resonance imaging (fMRI), which allows non‐invasive mapping of human cognitive functions, has become an important tool for understanding language function. An understanding of component processes and sources of noise in the images is contributing to increased confidence in the reproductability of studies. This allows clinical applications, e.g., for pre‐surgical lateralisation of language functions in patients with temporal lobe epilepsy. fMRI is a sensitive method for mapping regions involved in language functions. We recently have applied it to study the effect of word surface form on reading with a comparison of responses to Chinese characters or alphabetical Pinyin. Interpretation of fMRI activations must be made with caution; fMRI suggests task‐associated activation, but does not independently confirm that such activity is necessary. However, complementary studies can be performed using transcranial magnetic stimulation (TMS), which can be used to interfere with brain activity in a specific region transiently for characterisation of the behavioural effects. We describe how TMS combined with fMRI has confirmed a role for the left inferior frontal cortex in semantic processing. Hum. Brain Mapping 18:239–247, 2003. © 2003 Wiley‐Liss, Inc.
Scintigraphic method to detect silent aspiration during sleep in postsurgical patients with oral cancer
Authors: Tei Kanchu , Takinami Shu‐ichi , Yamazaki Yutaka , Totsuka Yasunori
Published: February 2003

Background.

A simple method to detect silent aspiration during sleep has not been established in postsurgical oral cancer patients.

Methods.

Radioactive paste consisting of 99mTcO4− and carboxylmethylcellulose was prepared and placed in a maxillary prosthesis with a cavity in the palatal space. The patient was requested to wear this appliance during sleep, and the following morning the patient was subjected to scintigraphic scanning. Both the anterior and posterior aspects of the thorax were scanned using a Shimazu Medical gamma camera with window settings adjusted to a low energy collimator at 500 kilocounts per image.

Results.

Silent aspiration that had not been detected by videofluoroscopic examination was clearly demonstrated by the scintigraphic method, showing aspiration of radioactive paste during sleep in the left thorax of the patient.

Conclusions.

The method reported for establishing aspiration is simple and reliable to assess silent aspiration during sleep in patients with oral cancer. © 2003 Wiley Periodicals, Inc. Head Neck 25: 245–250, 2003
The effect of radiation therapy on microcystic adnexal carcinoma: A case report
Authors: Stein Jeannine M. , Ormsby Adrian , Esclamado Ramon , Bailin Philip
Published: February 2003

Background.

Microcystic adnexal carcinoma (MAC) is a rare, locally aggressive tumor. Treatment for this neoplasm typically requires extensive local excision leading to morbidity. Therefore, the temptation to use alternative treatment options remains high.

Methods.

We report one case of a nasal dorsum MAC treated with external beam radiation secondary to the patient's poor health status and preference.

Results.

After initial dramatic clinical resolution, the tumor recurred in a clinically more extensive and histologically more aggressive form.

Conclusion.

On the basis of this case and several detailed in the literature, we therefore hypothesize that radiation therapy is not only an ineffective treatment for MAC, but evidence exists that this modality may induce conversion to a histologically and clinically less favorable neoplasm. © 2003 Wiley Periodicals, Inc. Head Neck 25: 251–254, 2003
Management of mandibular osteoradionecrosis corresponding to the severity of osteoradionecrosis and the method of radiotherapy
Authors: Notani Ken‐ichi , Yamazaki Yutaka , Kitada Hideyuki , Sakakibara Noriyuki , Fukuda Hiroshi , Omori Keiiti , Nakamura Motoyasu
Published: February 2003

Purpose.

To demonstrate appropriate treatment methods for mandibular osteoradionecrosis (ORN) by evaluating previous results.

Methods.

The relationship between the time interval after radiation therapy (RT) and the severity of ORN was examined. Eighty‐seven patients were classified according to the extent of the lesion (grades), and the cure rates were calculated according to the RT modality, the grade, and the treatment method for ORN.

Results.

The later ORN developed and the higher the dose of irradiation, particularly among the patients who received external RT, the more it progressed. The initial cure rates for conservative management, marginal, and segmental mandibulectomy were 39.7%, 50%, and 86.7%, respectively.

Conclusions.

Conservative management should be limited to early‐onset ORN after brachytherapy with or without a low dose of external irradiation. Marginal mandibulectomy is appropriate for the late‐onset ORN after brachytherapy with or without low‐dose external irradiation. Segmental mandibulectomy is required for late‐onset ORN after a high dose of external irradiation. © 2003 Wiley Periodicals, Inc. Head Neck 25: 181–186, 2003
Gamma knife radiosurgery for recurrent salivary gland malignancies involving the base of skull
Authors: Lee Nancy , Millender Laura E. , Larson David A. , Wara William M. , McDermott Michael W. , Kaplan Michael J. , Sneed Penny K.
Published: February 2003

Background.

The management of skull base recurrence of salivary gland tumors is challenging, because complete surgical resection and fractionated reirradiation are seldom possible. Experience is being gained with radiosurgery for this indication.

Methods.

From 1994–2000, eight patients with 16 skull base recurrences of salivary gland tumors underwent Gamma Knife radiosurgery at the University of California San Francisco. Local freedom from progression (FFP), regional FFP, locoregional FFP, and survival times were measured from the date of radiosurgery and estimated using the Kaplan‐Meier method.

Results.

All patients experienced symptomatic response, usually pain resolution. The median local FFP, regional FFP, locoregional FFP, and survival times were 15.4, 12.0, 10.0, and 21.2 months, respectively. The 1‐year local FFP probabilities are 93% and 59%, respectively. Local FFP, allowing for salvage radiosurgery, was 100% at 1 year and 75% at 2 years. Five of seven patients with locoregional failure underwent repeat radiosurgery, successfully achieving control for an additional 4.4 to 13.4 months in four patients. One patient had radiation necrosis develop.

Conclusion.

Radiosurgery provided good local control and symptomatic relief in patients with recurrent salivary gland malignancies involving the base of skull. In patients with good performance status, radiosurgery should be considered as salvage treatment. © 2003 Wiley Periodicals, Inc. Head Neck 25: 210–216, 2003