bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steigerung der Effizienz von Erdwärmesonden durch Luftinjektion an Standorten ohne Grundwasserströmung
Authors: Ma Xiaolong , Grabe Jürgen 
Published: March 2011

AbstractZur Nutzung der oberflächennahen Geothermie stehen geschlossene und offene Systeme zur Verfügung. In geschlossenen Systemen wird bei Fehlen einer Grundwasserströmung die Wärme im Boden durch Wärmeleitung transportiert. Dieses ist ein langsamer Vorgang und schränkt die Entzugsleistung von Erdwärmeanlagen ein. Es wird eine patentierte Methode vorgestellt, in der ein geschlossenes Erdwärmesystem mit Grundwasserzirkulationsverfahren kombiniert wird. Dadurch wird eine Zirkulationsströmung künstlich in Gang gesetzt, die zur Erhöhung des konvektiven Wärmetransports und der Leistung der Erdwärmeanlage führt. In diesem Beitrag wird eine mit Luftinjektionsbrunnen kombinierte Erdwärmesonde dreidimensional numerisch abgebildet. Die durch Luftinjektion erzeugte Grundwasserzirkulation sowie die Wärmeausbreitung im Boden werden sequenziell simuliert. Die Entzugsleistung dieser Anlage wird mit der einer üblichen Erdwärmeanlage verglichen. Weiterhin werden Variationsberechnungen durchgeführt, um den Einfluss der Dichte des Wasser‐ Luft‐Gemisches im Brunnen, der Wärmeleitfähigkeit und der Durchlässigkeit des Bodens zu untersuchen. Eine Wirtschaftlichkeitsanalyse vervollständigt diesen Beitrag.Increasing the efficiency of downhole heat exchangers by air sparging in locations without groundwater flow. Closed and open systems are available for the exploitation of shallow geothermal energy. If there is no groundwater flow, heat in closed systems can only be transferred by conduction. Unfortunately, heat conduction is a relatively slow heat transfer mechanism, which limits the heating capacity of geothermal systems. A patented method is presented, in which a closed system is combined with groundwater circulation technology. In this system, a groundwater circulation is created artificially, which increases the convective heat transfer in the soil and therefore the heat capacity of the geothermal system. In this paper a downhole heat exchanger combined with an air sparging well is numerically simulated. The groundwater circulation induced by air sparging and the heat propagation are calculated sequentially. The heat capacity of this system is compared with a normal downhole heat exchanger. Furthermore, variation calculations are performed to investigate the influence of the density of the water‐air mixture in the well, permeability and conductivity of the soil. A profitability analysis rounds off the paper.
Speech perception in the child brain: Cortical timing and its relevance to literacy acquisition
Authors: Parviainen Tiina , Helenius Päivi , Poskiparta Elisa , Niemi Pekka , Salmelin Riitta 
Published: March 2011

AbstractSpeech processing skills go through intensive development during mid‐childhood, providing basis also for literacy acquisition. The sequence of auditory cortical processing of speech has been characterized in adults, but very little is known about the neural representation of speech sound perception in the developing brain. We used whole‐head magnetoencephalography (MEG) to record neural responses to speech and nonspeech sounds in first‐graders (7‐8‐year‐old) and compared the activation sequence to that in adults. In children, the general location of neural activity in the superior temporal cortex was similar to that in adults, but in the time domain the sequence of activation was strikingly different. Cortical differentiation between sound types emerged in a prolonged response pattern at about 250 ms after sound onset, in both hemispheres, clearly later than the corresponding effect at about 100 ms in adults that was detected specifically in the left hemisphere. Better reading skills were linked with shorter‐lasting neural activation, speaking for interdependence of the maturing neural processes of auditory perception and developing linguistic skills. This study uniquely utilized the potential of MEG in comparing both spatial and temporal characteristics of neural activation between adults and children. Besides depicting the group‐typical features in cortical auditory processing, the results revealed marked interindividual variability in children. Hum Brain Mapp, 2011. © 2011 Wiley Periodicals, Inc.
Head injury or head motion? Assessment and quantification of motion artifacts in diffusion tensor imaging studies
Authors: Ling Josef , Merideth Flannery , Caprihan Arvind , Pena Amanda , Teshiba Terri , Mayer Andrew R. 
Published: March 2011

AbstractThe relationship between head motion and diffusion values such as fractional anisotropy (FA) and mean diffusivity (MD) is currently not well understood. Simulation studies suggest that head motion may introduce either a positive or negative bias, but this has not been quantified in clinical studies. Moreover, alternative measures for removing bias as result of head motion, such as the removal of problematic gradients, has been suggested but not carefully evaluated. The current study examined the impact of head motion on FA and MD across three common pipelines (tract‐based spatial statistics, voxelwise, and region of interest analyses) and determined the impact of removing diffusion weighted images. Our findings from a large cohort of healthy controls indicate that while head motion was associated with a positive bias for both FA and MD, the effect was greater for MD. The positive bias was observed across all three analysis pipelines and was present following established protocols for data processing, suggesting that current techniques (i.e., correction of both image and gradient table) for removing motion bias are likely insufficient. However, the removal of images with gross artifacts did not fundamentally change the relationship between motion and DTI scalar values. In addition, Monte Carlo simulations suggested that the random removal of images increases the bias and reduces the precision of both FA and MD. Finally, we provide an example of how head motion can be quantified across different neuropsychiatric populations, which should be implemented as part of any diffusion tensor imaging quality assurance protocol. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
Dissociation between anterior and posterior cortical regions during self‐specificity and familiarity: A combined fMRI–meta‐analytic study
Authors: Qin Pengmin , Liu Yijun , Shi Jinfu , Wang Yuzhi , Duncan Niall , Gong Qiyong , Weng Xuchu , Northoff Georg 
Published: March 2011

AbstractThe familiarity to the subject of any potential stimuli presents one of the major difficulties for the investigation of the self; the separation of effects resulting from familiarity from self‐effects being extremely problematic. The aim of this study was thus to investigate the neural distinction between self and familiarity by combining two sets of fMRI data with a meta‐analysis. In the first fMRI experiment, regions responding to self/familiarity were investigated using the subject's own name and names of familiar others. These effects were confirmed and extended in a second fMRI experiment using the subject's own name and a stranger's name, as spoken by familiar and unfamiliar voices. Finally, a meta‐analysis of self‐ and familiarity‐related studies was conducted. Neural activity in the anterior brain regions, such as the anterior cingulate (ACC) and anterior insula (AI), was found to be specific for self‐specific stimuli. In contrast, posterior brain regions, such as the posterior cingulate, were activated by familiar stimuli. Finally, the distinction between anterior and posterior regions for self and familiarity was confirmed by meta‐analytic data. This study demonstrates a clear anterior–posterior cortical partition between self‐specificity and familiarity. Hum Brain Mapp, 2012. © 2010 Wiley Periodicals, Inc.
Frontal parietal control network regulates the anti‐correlated default and dorsal attention networks
Authors: Gao Wei , Lin Weili 
Published: March 2011

AbstractRecent reports demonstrate the anti‐correlated behaviors between the default (DF) and the dorsal attention (DA) networks. We aimed to investigate the roles of the frontal parietal control (FPC) network in regulating the two anti‐correlated networks through three experimental conditions, including resting, continuous self‐paced/attended sequential finger tapping (FT), and natural movie watching (MW), respectively. The two goal‐directed tasks were chosen to engage either one of the two competing networks—FT for DA whereas MW for default. We hypothesized that FPC will selectively augment/suppress either network depending on how the task targets the specific network; FPC will positively correlate with the target network, but negatively correlate with the network anti‐correlated with the target network. We further hypothesized that significant causal links from FPC to both DA and DF are present during all three experimental conditions, supporting the initiative regulating role of FPC over the two opposing systems. Consistent with our hypotheses, FPC exhibited a significantly higher positive correlation with DA (P = 0.0095) whereas significantly more negative correlation with default (P = 0.0025) during FT when compared to resting. Completely opposite to that observed during FT, the FPC was significantly anti‐correlated with DA (P = 2.1e‐6) whereas positively correlated with default (P = 0.0035) during MW. Furthermore, extensive causal links from FPC to both DA and DF were observed across all three experimental states. Together, our results strongly support the notion that the FPC regulates the anti‐correlated default and DA networks. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
Neural basis of single‐word reading in Spanish–English bilinguals
Authors: Jamal Nasheed I. , Piche Ashley W. , Napoliello Eileen M. , Perfetti Charles A. , Eden Guinevere F. 
Published: March 2011

AbstractBrain imaging studies have identified a left‐lateralized network of regions that are engaged when monolinguals read. However, for individuals who are native speakers of two languages, it is unclear whether this pattern of activity is maintained across both languages or if it deviates according to language‐specific properties. We used functional magnetic resonance imaging to investigate single‐word processing in Spanish and in English in 12 proficient early Spanish–English bilinguals matched in skill level in both languages. Word processing in Spanish engaged the left inferior frontal and left middle temporal gyri. Word processing in English activated the left inferior frontal, middle frontal, and fusiform gyri extending to inferior temporal gyrus and the right middle temporal gyrus extending into superior temporal sulcus. The comparison of reading in Spanish greater than reading in English revealed involvement of the left middle temporal gyrus extending into the superior temporal sulcus. English greater than Spanish, however, demonstrated greater engagement of the left middle frontal gyrus extending into the superior frontal gyrus. We conclude that although word processing in either language activates classical areas associated with reading, there are language‐specific differences, which can be attributed to the disparity in orthographic transparency. English, an orthographically deep language, may require greater engagement of the frontal regions for phonological coding, whereas Spanish allows increased access to semantic processing via the left middle temporal areas. Together, these results suggest that bilinguals will show adjustments to the typical neural representation of reading as necessitated by the demands of the orthography. Hum Brain Mapp, 2012. © 2010 Wiley Periodicals, Inc.
Nonlinear estimation of neural processing time from BOLD signal with application to decision‐making
Authors: Biazoli Claudinei Eduardo , Sato João Ricardo , Cardoso Ellison Fernando , Brammer Michael John , Amaro Edson 
Published: March 2011

AbstractThe extraction of information about neural activity timing from BOLD signal is a challenging task as the shape of the BOLD curve does not directly reflect the temporal characteristics of electrical activity of neurons. In this work, we introduce the concept of neural processing time (NPT) as a parameter of the biophysical model of the hemodynamic response function (HRF). Through this new concept we aim to infer more accurately the duration of neuronal response from the highly nonlinear BOLD effect. The face validity and applicability of the concept of NPT are evaluated through simulations and analysis of experimental time series. The results of both simulation and application were compared with summary measures of HRF shape. The experiment that was analyzed consisted of a decision‐making paradigm with simultaneous emotional distracters. We hypothesize that the NPT in primary sensory areas, like the fusiform gyrus, is approximately the stimulus presentation duration. On the other hand, in areas related to processing of an emotional distracter, the NPT should depend on the experimental condition. As predicted, the NPT in fusiform gyrus is close to the stimulus duration and the NPT in dorsal anterior cingulate gyrus depends on the presence of an emotional distracter. Interestingly, the NPT in right but not left dorsal lateral prefrontal cortex depends on the stimulus emotional content. The summary measures of HRF obtained by a standard approach did not detect the variations observed in the NPT. Hum Brain Mapp, 2012. © 2010 Wiley Periodicals, Inc.
Sensitive period for white‐matter connectivity of superior temporal cortex in deaf people
Authors: Li Yanyan , Ding Guosheng , Booth James R. , Huang Ruiwang , Lv Yating , Zang Yufeng , He Yong , Peng Danling 
Published: March 2011

AbstractPrevious studies have shown that white matter in the deaf brain changes due to hearing loss. However, how white‐matter development is influenced by early hearing experience of deaf people is still unknown. Using diffusion tensor imaging and tract‐based spatial statistics, we compared white‐matter structures among three groups of subjects including 60 congenitally deaf individuals, 36 acquired deaf (AD) individuals, and 38 sex‐ and age‐matched hearing controls (HC). The result showed that the deaf individuals had significantly reduced fractional anisotropy (FA) values in bilateral superior temporal cortex and the splenium of corpus callosum compared to HC. The reduction of FA values in acquired deafness correlated with onset age of deafness, but not the duration of deafness. To explore the underlying mechanism of FA changes in the deaf groups, we further analyzed radial and axial diffusivities and found that (1) the reduced FA values in deaf individuals compared to HC is primarily driven by higher radial diffusivity values and (2) in the AD, higher radial diffusivity was correlated with earlier onset age of deafness, but not the duration of deafness. These findings imply that early sensory experience is critical for the growth of fiber myelination, and anatomical reorganization following auditory deprivation is sensitive to early plasticity in the brain. Hum Brain Mapp, 2012. © 2010 Wiley Periodicals, Inc.
Differential effects of intranasal insulin and caffeine on cerebral blood flow
Authors: Grichisch Yuko , Çavuşoğlu Mustafa , Preissl Hubert , Uludağ Kamil , Hallschmid Manfred , Birbaumer Niels , Häring Hans U. , Fritsche Andreas , Veit Ralf 
Published: March 2011

AbstractInsulin is an important modulator of brain functions such as memory and appetite regulation. Besides the effect on neuronal activity, it is also possible that insulin has a direct vasodilatory effect on cerebral blood flow (CBF). We investigated the impact of increased insulin levels in the central nervous system on basal and task‐induced CBF as well as blood oxygenation level‐dependent (BOLD) response in the visual cortex using pulsed arterial spin‐labeling MRI. An intranasal insulin application was used to avoid peripheral hyperinsulinaemia, which would lead to a cascade of hormonal changes. In a control experiment, caffeine was applied due to its well‐known impact on the vasculature of the brain leading to a reliable reduction of CBF. Eight lean subjects were included in the study. On 2 separate days, intranasal human insulin or caffeine tablets were given to the subjects after fasting over night. On each day, basal CBF and task‐induced CBF were measured before and 30 min after application of insulin or caffeine in each subject. During the task condition, a flickering checkerboard was presented. Insulin had no effect on basal CBF and task‐induced CBF in comparison with drug‐free baseline measurement in the visual cortex and control regions. After caffeine application, however, there was a significant decrease of CBF during stimulation in the visual cortex. The BOLD response was not altered by insulin or caffeine between pre‐ and postdose measurements. In conclusion, we found no evidence for a direct vasodilatory effect of intranasal insulin on the cerebral vascular system in this study. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
Seeing different objects in different ways: Measuring ventral visual tuning to sensory and semantic features with dynamically adaptive imaging
Authors: Cusack Rhodri , Veldsman Michele , Naci Lorina , Mitchell Daniel J. , Linke Annika C. 
Published: March 2011

AbstractA key challenge of object recognition is achieving a balance between selectivity for relevant features and invariance to irrelevant ones. Computational and cognitive models predict that optimal selectivity for features will differ by object, and here we investigate whether this is reflected in visual representations in the human ventral stream. We describe a new real‐time neuroimaging method, dynamically adaptive imaging (DAI), that enabled measurement of neural selectivity along multiple feature dimensions in the neighborhood of single referent objects. The neural response evoked by a referent was compared to that evoked by 91 naturalistic objects using multi‐voxel pattern analysis. Iteratively, the objects evoking the most similar responses were selected and presented again, to converge upon a subset that characterizes the referent's “neural neighborhood.” This was used to derive the feature selectivity of the response. For three different referents, we found strikingly different selectivity, both in individual features and in the balance of tuning to sensory versus semantic features. Additional analyses placed a lower bound on the number of distinct activation patterns present. The results suggest that either the degree of specificity available for object representation in the ventral stream varies by class, or that different objects evoke different processing strategies. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
Relationship between functional connectivity and sensory impairment: Red flag or red herring?
Authors: Dinomais Mickaël , Groeschel Samuel , Staudt Martin , Krägeloh‐Mann Ingeborg , Wilke Marko 
Published: March 2011

AbstractResting‐state functional magnetic resonance imaging (fMRI) can be used to study the functional connectivity in the somatosensory system. However, the relationship between sensory network connectivity, sensory deficits, and structural abnormality remains poorly understood. Previously, we investigated the motor network in children with congenital hemiparesis due to middle cerebral artery strokes (MCA, n = 6) or periventricular lesions (PL, n = 8). In the present study, we validate the use of interleaved resting‐state data from blocked fMRI designs to investigate the somatosensory network in these patients. The approach was validated by assessing the predicted “crossed‐over” connectivity between the cerebral cortex and the cerebellum. Furthermore, the impact on the volume of gray‐matter (GM) in primary (S1) and secondary (S2) somatosensory cortex on functional connectivity measures was investigated. We were able to replicate the well‐known “crossed‐over” pattern of functional connectivity between cerebral and cerebellar cortex. The MCA group displayed more sensory deficit and significantly reduced functional connectivity in the lesioned S2 (but not in lesioned S1) when compared with the PL group. However, when accounting for GM volume loss, this difference disappeared. This study demonstrates the applicability of analyzing resting‐state connectivity in patients with brain lesions. Reductions of functional connectivity within the somatosensory network were associated with sensory deficits, but were fully explained by the underlying GM damage. This underlines the influence of cortical GM volume on functional connectivity measures. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
Comparative study on toxic effects induced by oral or intravascular administration of commonly used disinfectants and surfactants in rats
Authors: Xue Yuying , Zhang Shanshan , Tang Meng , Zhang Ting , Wang Yiqing , Hieda Yoko , Takeshita Haruo 
Published: March 2011

ABSTRACTAccidental ingestion or injection of household products sometimes occurs due to their accessibility, but the toxic manifestations have not been well characterized when they are internally administered. The aim of this study was to investigate the toxic effects induced by ingestion or injection of different ionic surfactants and disinfectants in rats. The test drugs involved benzalkonium and benzethonium (BZK and BZT, both cationic surfactants used as disinfectants), alkyldiaminoethylglycine (AEG, an amphoteric surfactant used as a disinfectant), linear alkylbenzenesulfonate (LAS, an anionic surfactant), polyoxyethylene cetylether (PEC, a nonionic surfactant), chlorhexidine (CHX, not a surfactant but a disinfectant) and saline (control). Male Sprague–Dawley rats were administered one of the test drugs orally (p.o.), intravenously (i.v.) or intraarterially (i.a.). The fatal effects appeared rapidly (<30 min) in i.v.‐administered rats, while taking hours (>5 h) in i.a./p.o.‐administered rats after a dose of around LD50, although the progress and degree of toxic effects varied among the drugs tested. In intravascular administration, BZK and BZT were fatal at doses of 15–20 mg kg−1. Higher concentrations in lung and kidney than in blood were determined. CHX showed a high toxic effect compared with cationic surfactants. The rats administered anionic (LAS) or amphoteric (AEG) surfactant died in less than 24 h at doses over 100 mg kg−1. In p.o. administration, the toxic effects were concentration/dose‐dependent, and all rats administered high doses of surfactants except for PEC died at 5–20 h. The overall toxic ranks could be: cationic surfactant/CHX> anionic/amphoteric surfactant > nonionic surfactant. Copyright © 2011 John Wiley & Sons, Ltd.