bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multimodal integration of EEG and MEG data: A simulation study with variable signal‐to‐noise ratio and number of sensors
Authors: Babiloni Fabio , Babiloni Claudio , Carducci Filippo , Romani Gian Luca , Rossini Paolo M. , Angelone Leonardo M. , Cincotti Febo 
Published: March 2004

AbstractPrevious simulation studies have stressed the importance of the multimodal integration of electroencephalography (EEG) and magnetoencephalography (MEG) data in the estimation of cortical current density. In such studies, no systematic variations of the signal‐to‐noise ratio (SNR) and of the number of sensors were explicitly taken into account in the estimation process. We investigated effects of variable SNR and number of sensors on the accuracy of current density estimate by using multimodal EEG and MEG data. This was done by using as the dependent variable both the correlation coefficient (CC) and the relative error (RE) between imposed and estimated waveforms at the level of cortical region of interests (ROI). A realistic head and cortical surface model was used. Factors used in the simulations were: (1) the SNR of the simulated scalp data (with seven levels: infinite, 30, 20, 10, 5, 3, 1); (2) the particular inverse operator used to estimate the cortical source activity from the simulated scalp data (INVERSE, with two levels, including minimum norm and weighted minimum norm); and (3) the number of EEG or MEG sensors employed in the analysis (SENSORS, with three levels: 128, 61, 29 for EEG and 153, 61, or 38 in MEG). Analysis of variance demonstrated that all the considered factors significantly affect the CC and the RE indexes. Combined EEG–MEG data produced statistically significant lower RE and higher CC in source current density reconstructions compared to that estimated by the EEG and MEG data considered separately. These observations hold for the range of SNR values presented by the analyzed data. The superiority of current density estimation by multimodal integration of EEG and MEG was not due to differences in number of sensors between unimodal (EEG, MEG) and combined (EEG–MEG) inverse estimates. In fact, the current density estimate relative to the EEG–MEG multimodal integration involved 61 EEG plus 63 MEG sensors, whereas estimations carried out with the single modalities alone involved 128 sensors for EEG and 153 sensors for MEG. The results of the simulations also suggest that the use of simultaneous 29 EEG sensors during the MEG measurements carried out with full sensor arrangements (153 sensors) returned an accuracy of the cortical source estimate statistically similar to that obtained by combining 64 EEG and 153 MEG sensors. Hum. Brain Mapp. 22:54–64, 2004. © 2004 Wiley‐Liss, Inc.
Modulation of functional connectivity during the resting state and the motor task
Authors: Jiang Tianzi , He Yong , Zang Yufeng , Weng Xuchu 
Published: March 2004

AbstractQuite a few studies in functional magnetic resonance imaging (fMRI) have tested that, even in a resting state, motor cortices constitute a network. It has never been investigated how the network modulates from the resting state to the motor task state. In this report, by a newly developed approach taking into account n‐to‐1 connectivity using 1‐to‐1 connectivity measures instead of conventional pairwise connectivity, we show the existence of a large organized functional connectivity network related to motor function in the resting brain with fMRI. More importantly, we found that such a network can be modulated from a conscious resting state to planning, initiation, coordination, guidance, and termination of voluntary movement state, exhibited by significant changes of functional connectivity of some brain regions in different brain activity. Moreover, a quantitative description of such a functional modulation has also been presented. Hum. Brain Mapp. 22:65–73, 2004. © 2004 Wiley‐Liss, Inc.
Noninvasive optical imaging in the visual cortex in young infants
Authors: Kusaka Takashi , Kawada Kou , Okubo Kensuke , Nagano Keiko , Namba Masanori , Okada Hitoshi , Imai Tadashi , Isobe Kenichi , Itoh Susumu 
Published: March 2004

AbstractDuring the developmental stage, the brain undergoes anatomic, functional, and metabolic changes necessary to support the complex adaptive behavior of a mature individual. Estimation of developmental changes occurring in different regions of the brain would provide a means of relating various behavioral phenomena to maturation‐specific brain structures, thereby providing useful information on structure‐function relationships in both normal and disease states. We used multichannel near‐infrared spectroscopy (MNIRS), a new noninvasive imaging technique for revealing the course of neural activity in selected brain regions, to monitor the activities of the visual cortex as mirrored by hemodynamic responses in infants subjected to photostimulation during natural sleep. In the infants, oxyhemoglobin and total hemoglobin decreased and deoxyhemoglobin increased in the visual cortex with photostimulation. This pattern of responses was different from the response pattern in adults reported previously. The different patterns of responses to photostimulation in the visual cortices of infants and adults might reflect developmental and behavioral differences. It may reflect a different functional organization of the visual cortex in infants or ongoing retinal development. Our results demonstrated that regional hemodynamic change could be detected in a small area around the visual cortex. MNIRS offers considerable potential for research and noninvasive clinical applications. Hum. Brain Mapping 22:124–134, 2004. © 2004 Wiley‐Liss, Inc.
Novel 2‐phosphabicyclo[2.2.2]oct‐5‐ene derivatives and their use in phosphinylations
Authors: Keglevich György , Kovács János , Körtvélyesi Tamás , Parlagh Gyula , Imre Tímea , Ludányi Krisztina , Hegedűs László , Hanusz Miklós , Simon Kálmán , Márton Andrea , Marosi György , Tőke László 
Published: March 2004

AbstractThe [4 + 2] cycloaddition of the double‐bond isomers (A and B) of dihydrophosphinine oxide 1 afforded novel phosphabicyclo[2.2.2]oct‐5‐ene derivates (2–4), formation of which was justified by PM3 semiempirical calculations. The compounds of dimer type (2–4) were utilized in the UV light‐mediated fragmentation‐related phosphinylation of nucleophiles, especially in that of alcohols. To explore the role of structural modifications on the fragmentation ability, disulfide 5, phosphabicyclooctane 7 obtained by the hydrogenation of 2, and the adduct of dihydrophosphinine oxide 1 with benzoquinone (7) were also synthesized and tested in fragmentation. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:97–106, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10221
An iterative strategy for the synthesis of oligothiophenes by catalytic cross‐coupling reactions
Authors: Pinault Thomas , Chérioux Frédéric , Therrien Bruno , Süss‐Fink Georg 
Published: March 2004

AbstractAn iterative strategy for the synthesis of new sulfur‐functionalized oligothiophenes by Suzuki or Stille cross‐coupling reactions was applied to the reaction of 4‐bromo‐tert‐butylphenylthioether with thiophene derivatives. The planarity of the oligothiophenes obtained was confirmed by the single‐crystal X‐ray structure analysis of 2‐(4′‐tert‐butylthiophenyl)thiophene, which shows a potentially large electronic conjugation length. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:121–126, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10224
Chromophoric macrocycles from the oxidation of bis(aminofurazanylic) ethers of 1,2‐diols
Authors: Sheremetev Aleksei B. , Shatunova Elena V. , Averkiev Boris B. , Dmitriev Dmitrii E. , Petukhov Viktor A. , Antipin Mikhail Yu. 
Published: March 2004

AbstractA series of chromophoric azofurazan‐containing macrocycles 6a–c and 7a–d were synthesized from bis(aminofurazanylic) ethers of 1,2‐diols 4a–d by dibromoisocyanurate oxidation. The macrocycle closure is a result of NN bond formation. An ion‐binding ability of these compounds was tested. The macrocycles were characterized by NMR, MS, IR, and UV spectroscopy. The X‐ray crystal structures of the macrocycles 6a, 7c, and linear counterpart 12 are reported. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:131–145, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10226
1‐(Arylalkyl)quinolizidine Derivatives and Thio‐Isosteric Analogues as Ligands for Sigma Receptors
Authors: Sparatore Anna , Novelli Federica , Sparatore Fabio 
Published: March 2004

AbstractA set of 1‐(arylalkyl)quinolizidines, isosteric thioanalogues, and variously functionalized congeners were synthesized (see 1–25) and tested for affinity to sigma 1 and sigma 2 receptor subtypes, by displacing [3H]‐ (+)‐pentazocine and [3H]DTG from guinea pig brain and rat brain preparations, respectively. All compounds exhibited a good affinity for the σ1 subtype, with subnanomolar Ki values for the best of them, while only modest or poor affinity for the σ2 subtype was observed (Tables 1 and 2). Some structureactivity relationships were put forward.
Phenyl and Phenylethyl Glycosides from Picrorhiza scrophulariiflora
Authors: Huang Sheng‐Xiong , Liao Xun , Nie Quan‐Jiang , Ding Li‐Sheng , Peng Shu‐Lin 
Published: March 2004

AbstractThree new phenyl glycosides, scrophenoside A (1), B (2), and C (3), and two new phenylethyl glycosides, scroside D (4) and scroside E (5), were isolated from the stem of Picrorhiza scrophulariiflora Pennell (Scrophularlaceae), besides five known compounds. On the basis of spectroscopic evidence, the structures of the new compounds were elucidated as 4‐acetyl‐2‐methoxyphenyl 6‐O‐[4‐(β‐D‐glucopyranosyloxy)vanilloyl]‐β‐D‐glucopyranoside (1), 4‐acetylphenyl 6‐O‐[(E)‐p‐coumaroyl]‐β‐D‐glucopyranoside (2), 4‐[(1R)‐ and (1S)‐1‐hydroxyethyl]‐2‐methoxyphenyl β‐D‐glucopyranoside (3a and 3b, resp.), 2‐(3,4‐dihydroxyphenyl)ethyl O‐β‐D‐glucopyranosyl‐(1→3)‐4‐O‐[(E)‐feruloyl]‐β‐D‐glucopyranoside (4), and 2‐(3,4‐dihydroxyphenyl)ethyl O‐β‐D‐glucopyranosyl‐(1→3)‐6‐O‐[(E)‐feruloyl]‐β‐D‐glucopyranoside (5).
New Types of Very Efficient Photolabile Protecting Groups Based upon the [2‐(2‐Nitrophenyl)propoxy]carbonyl (NPPOC) Moiety
Authors: Bühler Sigrid , Lagoja Irene , Giegrich Heiner , Stengele Klaus‐Peter , Pfleiderer Wolfgang 
Published: March 2004

AbstractBased upon the photolabile [2‐(2‐nitrophenyl)propoxy]carbonyl group (NPPOC), a large number of modified 2‐(2‐nitrophenyl)propanol derivatives substituted at the phenyl ring (see 23–34 and 57–76) as well as at the side‐chain (see 85–92 and 95–98) were synthesized to improve the photoreactivity of this new type of photolabile entity. The phenyl moiety was also exchanged by the naphthalenyl group (see 102, 103, 105, 108, 110, 113, and 114), the thienyl substituent (see 115, 117, 118, and 120), and the benzothienyl substituent (see 121). The 2‐(2‐nitroaryl‐ and heteroaryl)propanols were converted with diphosgene into the corresponding carbonochloridates, which reacted subsequently with thymidine to the thymidine 5′‐(protected carbonates) 123–178 as the main reaction products. In several cases, the corresponding 3′‐carbonates and 3′,5′‐dicarbonates 179–212 were also isolated and characterized. Photolysis studies under standardized conditions (see Table) indicated that the rate of photocleavage varies in a broad range depending on the substituents. So far, the thymidine 5′‐[2‐(5‐halo‐2‐nitrophenyl)propyl carbonates] 127–129, 5′‐[2‐(nitro[1,1′‐biphenyl]3‐yl)propyl carbonates] 136–139, 5′‐{2‐[2‐nitro‐5‐(thianthren‐1‐yl)phenyl]propyl carbonate} (140), 5′‐[2‐(5‐naphthalenyl‐2‐nitrophenyl)propyl carbonates] 141 and 142, and 5′‐[2‐(2‐nitro‐5‐thienylphenyl)propyl carbonates] 143 and 144 showed the best properties regarding fast and uniform deprotection. Since the nucleobases of 213–215 do not influence the photocleavage features, in general, the new type of photolabile building blocks allows in form of their 3′‐phosphoramidites the photolithographic formation of high‐quality biochips.
Four New Diterpenoids from Ballota limbata
Authors: Ahmad Viqar Uddin , Farooq Umar , Abbaskhan Ahmed , Hussain Javid , Abbasi Muhammad Athar , Nawaz Sarfraz Ahmad , Choudhary M. Iqbal 
Published: March 2004

AbstractSix diterpenoids (1–6) belonging to the clerodane and tetracyclic diterpene types were isolated from the CHCl3 extract of Ballota limbata. The structures of the new compounds 1 and 4–6 (named ballatenolide A and limbatenolides A–C, resp.) were established by their spectral data, and their relative configuration was determined by 2D NMR. Compounds 2 and 3 were identified as known clerodanes. Compound 1 had a unique feature, i.e., an α,β‐unsaturated γ‐lactone moiety at C(4)/C(6), whereas limbatenolides A–C (4–6) belonged to the rare class of tetracyclic diterpenoids, which are known to occur only in the genus Ballota. All of the isolated compounds showed inhibitory potential in a cholinesterase‐inhibition assay.
Oxidative Rearrangement of 1‐Alkylidene‐1,2,3,4‐tetrahydro‐2‐(trichloroacetyl)isoquinolines to 1,5,6,10b‐Tetrahydro‐10b‐(trichloromethyl)‐3H‐oxazolo[4,3‐a]isoquinolin‐3‐ones
Authors: Lenz George R. , Lessor Ralph A. , Rafalko Patrice W. , Ezell Edward F. , Kosarych Zenyk , Meyer Lars , Margaretha Paul 
Published: March 2004

AbstractOn treatment with lead tetraacetate (Pb(OAc)4), the 1‐(alkylidene)‐1,2,3,4‐tetrahydro‐N‐(trichloroacetyl)isoquinolines 2a–2c as well as the tribromoacetyl derivative 4 undergo an oxidative cyclization with concomitant migration of the trihalogenomethyl group to afford the 1,5,6,10b‐tetrahydro‐10b‐(trichloromethyl)‐3H‐oxazolo[4,3‐a]isoquinolin‐3‐ones 3a–3c or the tribromomethyl derivative 6, respectively. These tricycles are also accessible via esterification of 3,4‐dihydro‐1‐(1‐hydroxy‐1‐methylethyl)isoquinoline 8 with either trichloroacetyl chloride or tribromoacetyl bromide, respectively. A plausible mechanistic description for these reactions involves an – unprecedented – ‘intramolecular iminohaloform’ rearrangement.
Solid‐Phase Synthesis of Oligo(triacetylene)s and Oligo(phenylenetriacetylene)s Employing Sonogashira and CadiotChodkiewicz‐Type Cross‐Coupling Reactions
Authors: Utesch Nils F. , Diederich François , Boudon Corinne , Gisselbrecht Jean‐Paul , Gross Maurice 
Published: March 2004

AbstractWe describe the first polymer‐supported synthesis of poly(triacetylene)‐derived monodisperse oligomers, utilizing Pd0‐catalyzed Sonogashira and CadiotChodkiewicz‐type cross‐couplings as the key steps in the construction of the acetylenic scaffolds. For our investigations, Merrifield resin functionalized with a 1‐(4‐iodoaryl)triazene linker was chosen as the polymeric support (R2; Figure and Scheme 3). The linker selection was made based on the results of several model studies in the liquid phase (Schemes 1 and 2). For the solid‐support synthesis of the oligo(phenylene triacetylene)s 7b–7d, a set of only three reactions was required: i) Pd0‐catalyzed Sonogashira cross‐coupling, ii) Me3Sialkyne deprotection by protodesilylation, and iii) cleavage of the linker with liberation of the generated oligomers (Scheme 5). The longest‐wavelength absorption maxima of the oligo(phenylene triacetylene)s 7a–7d shift bathochromically with increasing oligomeric length, from λmax 337 nm (monomer 7a) to 384 nm (tetramer 7d; Table 2). Based on the electronic absorption data, the effective conjugation length (ECL) of the oligo(phenylene triacetylene)s is estimated to involve at least four monomer units and 40 C‐atoms. π‐Electron conjugation in these oligomers is less efficient than in the known oligo(triacetylene)s 14a–14d (Table 2) due to poor transmittance of π‐electron delocalization by the phenyl rings inserted into the oligomeric backbone. Similar conclusions were drawn from the electrochemical properties of the two oligomeric series as determined by cyclic (CV) and rotating‐disk voltammetry (RDV; Table 3). In sharp contrast to 14b–14d, the oligo(phenylene triacetylene)s 7b–7d are strongly fluorescent, with the highest quantum yield ΦF=0.69 measured for trimer 7c (Table 2). Whereas the Sonogashira cross‐coupling on solid support proceeded smoothly, optimal conditions for alkynealkyne cross‐coupling reactions employing Pd0‐catalyzed CadiotChodkiewicz conditions still remain to be developed, despite extensive experimentation (Scheme 7 and Table 1).
Analytical solution to a bias in the TOPMODEL framework balance
Authors: Saulnier G.‐M. , Datin R. 
Published: March 2004

AbstractThe increasing need for distributed hydrological modelling leads to an intense use of spatially distributed predictions of physically based models, such as TOPMODEL as addressed here. The ability of these models to reproduce the internal behaviour of catchments physically is increasingly tested through field experiments (geochemical investigation, distributed measurements network, etc.). This paper will show that, in the case of TOPMODEL, an implicit approximation remains in the classic derivation of the equations that consists in neglecting the surface of saturated areas with respect to the total surface of the catchment. This simplifying, though unnecessary, approximation leads to a systematic underestimation of the catchment water storage deficit and to divergence in the water budget accounting. This may also significantly change the predicted ratio between subsurface and surface water fluxes in the total discharge. An analytical solution is suggested that leads to water balance accounting which is better defined, and more consistent in comparison with field water storage recording. It is expected that this work will ensure more accurate TOPMODEL predictions, consistent with the assumptions of the model. This will then improve the interpretation of comparisons between results of simulation and field experiments. Copyright © 2004 John Wiley & Sons, Ltd.
Seasonal and interannual variations of nitrate and chloride in stream waters related to spatial and temporal patterns of groundwater concentrations in agricultural catchments
Authors: Martin C. , Aquilina L. , Gascuel‐Odoux C. , Molénat J. , Faucheux M. , Ruiz L. 
Published: March 2004

AbstractNitrate concentrations in streamwater of agricultural catchments often exhibit interannual variations, which are supposed to result from land‐use changes, as well as seasonal variations mainly explained by the effect of hydrological and biogeochemical cycles. In catchments on impervious bedrock, seasonal variations of nitrate concentrations in streamwater are usually characterized by higher nitrate concentrations in winter than in summer. However, intermediate or inverse cycles with higher concentrations in summer are sometimes observed. An experimental study was carried out to assess the mechanisms that determine the seasonal cycles of streamwater nitrate concentrations in intensive agricultural catchments. Temporal and spatial patterns of groundwater concentrations were investigated in two adjacent catchments located in south‐western Brittany (France), characterized by different seasonal variations of streamwater nitrate concentrations. Wells were drilled across the hillslope at depths ranging from 1·5 to 20 m. Dynamics of the water table were monitored and the groundwater nitrate and chloride concentrations were measured weekly over 2 years. Results highlighted that groundwater was partitioned into downslope domains, where denitrification induced lower nitrate concentrations than into mid‐slope and upslope domains. For one catchment, high subsurface flow with high nitrate concentrations during high water periods and active denitrification during low water periods explained the higher streamwater nitrate concentrations in winter than in summer. For the other catchment, the high contribution of groundwater with high nitrate concentrations smoothed or inverted this trend. Increasing bromide/chloride ratio and nitrate concentrations with depth argued for an effect of past agricultural pressure on this catchment. The relative contribution of flows in time and correlatively the spatial origin of waters, function of the depth and the location on the hillslope, and their chemical characteristics control seasonal cycles of streamwater nitrate concentrations and can influence their interannual trends. Copyright © 2004 John Wiley & Sons, Ltd.
Factors governing the formation and persistence of layers in a subalpine snowpack
Authors: Gustafsson David , Waldner Peter A. , Stähli Manfred 
Published: March 2004

AbstractThe layered structure of a snowpack has a great effect on several important physical processes, such as water movement, reflection of solar radiation or avalanche release. Our aim was to investigate what factors are most important with respect to the formation and persistence of distinct layers in a subalpine environment. We used a physically based numerical one‐dimensional model to simulate the development of a snowpack on a subalpine meadow in central Switzerland during one winter season (1998–99). A thorough model validation was based on extensive measurement data including meteorological and snow physical parameters. The model simulated the snow water equivalent and the depth of the snowpack as well as the energy balance accurately. The observed strong layering of the snowpack, however, was not reproduced satisfactorily. In a sensitivity analysis, we tested different model options and parameter settings significant for the formation of snow layers. The neglection of effects of snow microstructure on the compaction rate, and the current description of the water redistribution inside the snowpack, which disregard capillary barrier effects, preferential flow and lateral water flow, were the major limitations for a more realistic simulation of the snowpack layering. Copyright © 2004 John Wiley & Sons, Ltd.