bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arterial spin labeling measurement of cerebral perfusion in children with sickle cell disease
Authors: Gevers Sanna , Nederveen Aart J. , Fijnvandraat Karin , van den Berg Sandra M. , van Ooij Pim , Heijtel Dennis F. , Heijboer Harriët , Nederkoorn Paul J. , Engelen Marc , van Osch Matthias J. , Majoie Charles B. 
Published: November 2011

AbstractPurpose:To evaluate the applicability of arterial spin labeling (ASL) cerebral blood flow (CBF) measurements in children with sickle cell disease (SCD).Materials and Methods:We included 12 patients and five controls. Conventional magnetic resonance imaging (MRI) (T2, fluid attenuated inversion recovery [FLAIR], and MR angiography) was performed to diagnose silent infarcts, vasculopathy, or leukoencephalopathy. Pseudo‐continuous ASL was performed to measure CBF using two postlabeling delays to identify transit‐time effects. Perfusion estimates were corrected for hematocrit and blood velocity in the labeling plane and compared to phase‐contrast MR. CBF asymmetries between the flow maps of the left and right internal carotid arteries were tested for significance using paired t‐tests. Significant asymmetries were expressed in terms of an asymmetry ratio (AR = absolute difference/mean). An AR >10% was considered clinically relevant.Results:Mean CBF was higher in patients than in controls. Agreement between CBF and flow improved after applying hematocrit and velocity corrections. At a 2100 msec postlabeling delay one patient had a clinically relevant asymmetry. No association was observed between CBF asymmetries and silent infarcts.Conclusion:Care must be taken in the interpretation of ASL‐CBF measurements in SCD patients. A long postlabeling delay with blood velocity correction anticipates overestimation of CBF asymmetries. J. Magn. Reson. Imaging 2012;35:779‐787. © 2011 Wiley Periodicals, Inc.
Comparison of a 28‐channel receive array coil and quadrature volume coil for morphologic imaging and T2 mapping of knee cartilage at 7T
Authors: Chang Gregory , Wiggins Graham C. , Xia Ding , Lattanzi Riccardo , Madelin Guillaume , Raya Jose G. , Finnerty Matthew , Fujita Hiroyuki , Recht Michael P. , Regatte Ravinder R. 
Published: November 2011

AbstractPurpose:To compare a new birdcage‐transmit, 28‐channel receive array (28‐Ch) coil and a quadrature volume coil for 7T morphologic MRI and T2 mapping of knee cartilage.Materials and Methods:The right knees of 10 healthy subjects were imaged on a 7T whole body magnetic resonance (MR) scanner using both coils. 3D fast low‐angle shot (3D‐FLASH) and multiecho spin‐echo (MESE) sequences were implemented. Cartilage signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), thickness, and T2 values were assessed.Results:SNR/CNR was 17%–400% greater for the 28‐Ch compared to the quadrature coil (P ≤ 0.005). Bland–Altman plots show mean differences between measurements of tibial/femoral cartilage thickness and T2 values obtained with each coil to be small (−0.002 ± 0.009 cm / 0.003 ± 0.011 cm) and large (−6.8 ± 6.7 msec/−8.2 ± 9.7 msec), respectively. For the 28‐Ch coil, when parallel imaging with acceleration factors (AF) 2, 3, and 4 was performed SNR retained was: 62%–69%, 51%–55%, and 39%–45%.Conclusion:A 28‐Ch knee coil provides increased SNR/CNR for 7T cartilage morphologic imaging and T2 mapping. Coils should be switched with caution during clinical studies because T2 values may differ. The greater SNR of the 28‐Ch coil could be used to perform parallel imaging with AF2 and obtain similar SNR as the quadrature coil. J. Magn. Reson. Imaging 2012;441‐448. © 2011 Wiley Periodicals, Inc.
Speech processing: From peripheral to hemispheric asymmetry of the auditory system
Authors: Lazard Diane S. , Collette Jean‐Louis , Perrot Xavier 
Published: November 2011

AbstractLanguage processing from the cochlea to auditory association cortices shows side‐dependent specificities with an apparent left hemispheric dominance. The aim of this article was to propose to nonspeech specialists a didactic review of two complementary theories about hemispheric asymmetry in speech processing. Starting from anatomico‐physiological and clinical observations of auditory asymmetry and interhemispheric connections, this review then exposes behavioral (dichotic listening paradigm) as well as functional (functional magnetic resonance imaging and positron emission tomography) experiments that assessed hemispheric specialization for speech processing. Even though speech at an early phonological level is regarded as being processed bilaterally, a left‐hemispheric dominance exists for higher‐level processing. This asymmetry may arise from a segregation of the speech signal, broken apart within nonprimary auditory areas in two distinct temporal integration windows—a fast one on the left and a slower one on the right—modeled through the asymmetric sampling in time theory or a spectro‐temporal trade‐off, with a higher temporal resolution in the left hemisphere and a higher spectral resolution in the right hemisphere, modeled through the spectral/temporal resolution trade‐off theory. Both theories deal with the concept that lower‐order tuning principles for acoustic signal might drive higher‐order organization for speech processing. However, the precise nature, mechanisms, and origin of speech processing asymmetry are still being debated. Finally, an example of hemispheric asymmetry alteration, which has direct clinical implications, is given through the case of auditory aging that mixes peripheral disorder and modifications of central processing.
Cationic Polymerization of Styrene Derivatives and Cyclopentadiene Catalyzed by B(C6F5)3 in Aqueous Media: Comparison of Suspension, Emulsion and Dispersion Processes
Authors: Kostjuk Sergei V. , Ganachaud Francois , Radchenko Alexei V. , Vasilenko Irina V. 
Published: November 2011

AbstractSummary: The cationic polymerization of styrene derivatives [p‐methoxystyrene (pMOS), p‐hydroxystyrene (pHS), styrene (St)] and cyclopentadiene (CPD) using B(C6F5)3‐based initiating systems in aqueous media is reported, focusing specifically on the influence of various additives (surfactant, solvent) on the control of the polymerization rate and molar masses. 1‐(4‐Methoxyphenyl)ethanol (1)/B(C6F5)3 system induced living dispersion (in solvent/water mixture, without surfactant) cationic polymerize‐tion of pMOS and pHS, affording polymers which Mns increased in direct proportion to monomer conversion (Mn ≤ 4500 g mol−1) and which exhibited rather narrow molecular weight distributions (Mw/Mn ≤ 1.5). Polymerization of St and CPD in suspension (in water without surfactant) proceeded uniquely through activation of the initiator followed by irreversible termination by water giving oligomers with Mn ≤ 2000 g mol−1 and Mw/Mn ≤ 2.0. Besides, pHS also polymerized in a living fashion under emulsion (in micellar aqueous solutions) conditions (Mn ≤ 4500 g mol−1; Mw/Mn ≤ 1.5) using either BRIJ®97 or hexa‐decyltrimethylammonium bromide (CTAB) as surfactants, whereas conventional non‐living cationic polymerization occurred with pMOS (using BRIJ®97 or CTAB as surfactants) and CPD (using dodecylbenzenesulfonic acid, DBSA).
Investigation of 1,1‐diphenylethylene Oligomerization in the End‐Capping Reaction of Poly(styryl)lithium
Authors: Quirk Roderic P. , Garces Camila , Dabney David , Polce Michael J. , Wesdemiotis Chris 
Published: November 2011

AbstractSummary: The possible oligomerization of 1,1‐diphenylethylene (DPE) in the end‐capping reaction of poly(styryl)lithium (PSLi) was studied in hydrocarbon solvents using excess DPE (≤16 mol‐eq); the effect of addition of THF (30 mol‐eq Lewis base) and extended times of reaction (8‐24 h) were also investigated. The characterization of the polymers was made by size exclusion chromatography (SEC), proton nuclear magnetic resonance spectroscopy (1H NMR) and matrix‐assisted laser desorption/ionization time of flight mass spectrometry (MALDI‐TOF MS). MALDI‐ TOF mass spectrometric results revealed the absence of DPE oligomerization under the reaction conditions used in this study.
Environmental tobacco smoke and Parkinson's disease
Authors: Searles Nielsen Susan , Gallagher Lisa G. , Lundin Jessica I. , Longstreth W.T. , Smith‐Weller Terri , Franklin Gary M. , Swanson Phillip D. , Checkoway Harvey 
Published: November 2011

AbstractBackground:Parkinson's disease is inversely associated with cigarette smoking, but its relation with passive smoking or environmental tobacco smoke exposure is rarely examined.Methods:Within a case–control study, we assessed the association between Parkinson's disease and living or working with active smokers. Cases were newly diagnosed with idiopathic Parkinson's disease (n = 154) from western Washington State in 2002–2008. Age‐ and sex‐matched controls (n = 173) were neurologically normal and unrelated to cases.Results:Compared with never active or passive tobacco smokers, we observed reduced Parkinson's disease risks for ever passive only smokers (OR, 0.34; 95% CI, 0.16–0.73), similar to those for ever active smokers (OR, 0.35; 95% CI, 0.17–0.73). Among persons whose only tobacco smoke exposure was passive smoking at home, risk was inversely associated with years exposed.Conclusions:These observations parallel those well established for active smoking. However, it remains unresolved whether a true protective effect of tobacco smoke, generally detrimental to health, underlies these associations. © 2011 Movement Disorder Society
The A3 adenosine receptor as multifaceted therapeutic target: pharmacology, medicinal chemistry, and in silico approaches
Authors: Cheong Siew Lee , Federico Stephanie , Venkatesan Gopalakrishnan , Mandel Alexander Laurence , Shao Yi‐Ming , Moro Stefano , Spalluto Giampiero , Pastorin Giorgia 
Published: November 2011

AbstractAdenosine is an ubiquitous local modulator that regulates various physiological and pathological functions by stimulating four membrane receptors, namely A1, A2A, A2B, and A3. Among these G protein‐coupled receptors, the A3 subtype is found mainly in the lung, liver, heart, eyes, and brain in our body. It has been associated with cerebroprotection and cardioprotection, as well as modulation of cellular growth upon its selective activation. On the other hand, its inhibition by selective antagonists has been reported to be potentially useful in the treatment of pathological conditions including glaucoma, inflammatory diseases, and cancer. In this review, we focused on the pharmacology and the therapeutic implications of the human (h)A3 adenosine receptor (AR), together with an overview on the progress of hA3AR agonists, antagonists, allosteric modulators, and radioligands, as well as on the recent advances pertaining to the computational approaches (e.g., quantitative structure–activity relationships, homology modeling, molecular docking, and molecular dynamics simulations) applied to the modeling of hA3AR and drug design.  © 2011 Wiley Periodicals, Inc. Med Res Rev
Copolymerization of VDF and HFP in Supercritical Carbon Dioxide: A Robust Approach for Modeling Precipitation and Dispersion Kinetics
Authors: Costa Liborio I. , Storti Giuseppe , Morbidelli Massimo , Ferro Loredana , Galia Alessandro , Scialdone Onofrio , Filardo Giuseppe 
Published: November 2011

AbstractA kinetic model is developed for the heterogeneous free‐radical copolymerization of vinylidene fluoride and hexafluoropropylene in supercritical CO2. The model accounts for polymerization in both the dispersed (polymer‐rich) phase and in the continuous (polymer‐free) supercritical phase, for radical interphase transport, diffusion limitations, and chain‐length‐dependent termination in the polymer‐rich phase. A parameter evaluation strategy is developed and detailed to estimate most of the kinetic parameters a priori while minimizing their evaluation by direct fitting. The resulting model predictions compare favorably with the experimental results of conversion and MWD at varying monomer feed composition, monomer concentration, interphase area, and pressure of the system.magnified image
Improved nanocrystal formation, quantum confinement and carrier transport properties of doped Si quantum dot superlattices for third generation photovoltaics
Authors: Di Dawei , Xu Heli , Perez‐Wurfl Ivan , Green Martin A. , Conibeer Gavin 
Published: November 2011

ABSTRACTAn all‐Si tandem solar cell has the potential to achieve high conversion efficiency at low cost. However, the selection and synthesis of candidate material remain challenging. In this work, we show that the conventional ‘Si quantum dots (Si QDs) in SiO2 matrix’ approach can lead to the formation of over‐sized Si nanocrystals especially when doped with phosphorous, making the size‐dependent quantum confinement less effective. Also, our investigation has shown that the high resistivity of this material has become the performance bottleneck of the solar cell. To resolve these matters, we propose a new design based on Si QDs embedded in a SiO2/Si3N4 hybrid matrix. By replacing the SiO2 tunnel barriers by the Si3N4 layers, the new material manages to constrain the growth of doped Si QDs effectively and enhances the apparent band gap, as shown in X‐ray diffraction, Raman, photoluminescence and optical spectroscopic measurements. Besides, electrical characterisation on Si QD/c‐Si heterointerface test structures indicates the new material possesses improved vertical carrier transport properties. Copyright © 2011 John Wiley & Sons, Ltd.
Inward facing conformations of the MetNI methionine ABC transporter: Implications for the mechanism of transinhibition
Authors: Johnson Eric , Nguyen Phong T. , Yeates Todd O. , Rees Douglas C. 
Published: November 2011

AbstractTwo new crystal structures of the Escherichia coli high affinity methionine uptake ATP Binding Cassette (ABC) transporter MetNI, purified in the detergents cyclohexyl‐pentyl‐β‐D‐maltoside (CY5) and n‐decyl‐β‐D‐maltopyranoside (DM), have been solved in inward facing conformations to resolutions of 2.9 and 4.0 Å, respectively. Compared to the previously reported 3.7 Å resolution structure of MetNI purified in n‐dodecyl‐β‐D‐maltopyranoside (DDM), the higher resolution of the CY5 data enabled significant improvements to the structural model in several regions, including corrections to the sequence registry, and identification of ADP in the nucleotide binding site. CY5 crystals soaked with selenomethionine established details of the methionine binding site in the C2 regulatory domain of the ABC subunit, including the displacement of the side chain of MetN residue methionine 301 by the exogenous ligand. When compared to the CY5 or DDM structures, the DM structure exhibits a significant repositioning of the dimeric C2 domains, including an unexpected register shift in the intermolecular β‐sheet hydrogen bonding between monomers, and a narrowing of the nucleotide binding space. The immediate proximity of the exogenous methionine binding site to the conformationally variable dimeric interface provides an indication of how methionine binding to the regulatory domains might mediate the phenomenon of transinhibition.
Modeling large regions in proteins: Applications to loops, termini, and folding
Authors: Adhikari Aashish N. , Peng Jian , Wilde Michael , Xu Jinbo , Freed Karl F. , Sosnick Tobin R. 
Published: November 2011

AbstractTemplate‐based methods for predicting protein structure provide models for a significant portion of the protein but often contain insertions or chain ends (InsEnds) of indeterminate conformation. The local structure prediction “problem” entails modeling the InsEnds onto the rest of the protein. A well‐known limit involves predicting loops of ≤12 residues in crystal structures. However, InsEnds may contain as many as ∼50 amino acids, and the template‐based model of the protein itself may be imperfect. To address these challenges, we present a free modeling method for predicting the local structure of loops and large InsEnds in both crystal structures and template‐based models. The approach uses single amino acid torsional angle “pivot” moves of the protein backbone with a Cβ level representation. Nevertheless, our accuracy for loops is comparable to existing methods. We also apply a more stringent test, the blind structure prediction and refinement categories of the CASP9 tournament, where we improve the quality of several homology based models by modeling InsEnds as long as 45 amino acids, sizes generally inaccessible to existing loop prediction methods. Our approach ranks as one of the best in the CASP9 refinement category that involves improving template‐based models so that they can function as molecular replacement models to solve the phase problem for crystallographic structure determination.
Effects of three reducing agents on pasting properties of stored rice
Authors: Guo Yubao , Tu Kang , Pan Leiqing , Zhang Wei , Zhang Yincheng 
Published: November 2011

AbstractThe effects of three reducing agents (dithiothreitol, ascorbic acid, and tea polyphenols) on pasting properties of fresh and aged rice were investigated using Rapid Visco Analyzer. Results showed that ascorbic acid did not only significantly increase peak viscosity (PV) and breakdown of aged rice in a concentration dependent manner (p<0.05), but also decreased its setback significantly (p<0.05). Dithiothreitol increased the PV, breakdown and setback of the aged rice. Importantly, the extent of ascorbic acid enhancing PV of the aged rice was higher than that of dithiothreitol, and showed positive dose‐effect relationship. Compared with ascorbic acid and dithiothreitol, tea polyphenols only significantly decreased setback of the aged rice (p<0.05). It was concluded that ascorbic acid was the most effective improver on pasting properties of aged rice as compared to dithiothreitol or tea polyphenols, especially in increasing PV and breakdown, and in decreasing setback. This showed rice ageing included, but was not limited, to the formation of disulfides, and more changes of ageing would involve hydrogen bonding and hydrophobic interactions. The different influences of SDS on fresh rice and aged rice also confirmed these findings to a certain extent. The improved role of ascorbic acid was ascribed to enhancing water absorption capacity, soluble solid content and granule swelling capacity of the aged rice.
Direct cellular reprogramming in Caenorhabditis elegans: facts, models, and promises for regenerative medicine
Authors: Zuryn Steven , Daniele Thomas , Jarriault Sophie 
Published: November 2011

AbstractIn vitro systems of cellular reprogramming [induced pluripotent stem (iPS) cells and direct reprogramming or transdifferentiation] are rapidly improving our repertoire of molecular techniques that can force cells in culture to change into a desired identity. However, the new frontier for regenerative medicine is in vivo cellular reprogramming, which in light of concerns about the safety of in vitro cell manipulations, is an increasingly attractive approach for regenerative medicine. Powerful in vivo approaches are currently being undertaken in the genetic model Caenorhabditis elegans. Several very distinct cell types have been induced to change or have been discovered to transform naturally, into altogether different cell types. These examples have improved our understanding of the fundamental molecular and cellular mechanisms that permit cell identity changes in live animals. In addition, the combination of a stereotyped lineage with single cell analyses allows dissection of the early and intermediate mechanisms of reprogramming, as well as their kinetics. As a result, several important concepts on in vivo cellular reprogramming have been recently developed. WIREs Dev Biol 2012, 1:138–152. doi: 10.1002/wdev.7This article is categorized under:

Gene Expression and Transcriptional Hierarchies > Nuclear Reprogramming
Gene Expression and Transcriptional Hierarchies > Cellular Differentiation
Invertebrate Organogenesis > Worms
Adult Stem Cells, Tissue Renewal, and Regeneration > Stem Cell Differentiation and Reversion
The impact of turbulence intensity and atmospheric stability on power deficits due to wind turbine wakes at Horns Rev wind farm
Authors: Hansen Kurt S. , Barthelmie Rebecca J. , Jensen Leo E. , Sommer Anders 
Published: November 2011

ABSTRACTThe wind turbine operational characteristics, power measurements and meteorological measurements from Horns Rev offshore wind farm have been identified, synchronized, quality screened and stored in a common database as 10 min statistical data. A number of flow cases have been identified to describe the flow inside the wind farm, and the power deficits along rows of wind turbines have been determined for different inflow directions and wind speed intervals. A method to classify the atmospheric stability based on the Bulk‐Ri number has been implemented. Long‐term stability conditions have been established, which confirms, in line with previous results, that conditions tend towards near neutral as wind speeds increase but that both stable and unstable conditions are present at wind speeds up to 15 m s −1. Moreover, there is a strong stability directional dependence with southerly winds having fewer unstable conditions, whereas northerly winds have fewer observations in the stable classes. Stable conditions also tend to be associated with lower levels of turbulence intensity, and this relationship persists as wind speeds increase. Power deficit is a function of ambient turbulence intensity. The level of power deficit is strongly dependent on the wind turbine spacing; as turbulence intensity increases, the power deficit decreases. The power deficit is determined for four different wind turbine spacing distances and for stability classified as very stable, stable and others (near neutral to very unstable). The more stable the conditions are, the larger the power deficit. Copyright © 2011 John Wiley & Sons, Ltd.
Cryo‐electron microscopy of ribosomal complexes in cotranslational folding, targeting, and translocation
Authors: Knoops Kèvin , Schoehn Guy , Schaffitzel Christiane 
Published: November 2011

AbstractSingle‐particle cryo‐electron microscopy (cryo‐EM) became a well‐established method to study the structure and function of large macromolecular assemblies in a close to physiological environment. Cryo‐EM reconstructions of ribosomal complexes trapped at different stages during translation, cotranslational targeting, and translocation provide new insights on a molecular level into these processes, which are vital for the correct localization and folding of all proteins in the cell. The EM structures in combination with biochemical experiments and available high‐resolution crystal or nuclear magnetic resonance (NMR) structures of individual factors and of the ribosome allow for interpretation in quasi‐atomic detail of the molecular mechanism of ribosomal complexes, their conformational changes and dynamic interactions with factors like the signal recognition particle, SRP receptor, the translocon, and the chaperone trigger factor. The snapshots obtained by single‐particle EM reconstructions enable us to follow the path of a nascent protein from the peptidyl‐transferase center, through the ribosomal tunnel, to and across the translocon in the membrane. With new developments in image processing techniques it is possible to sort a biological homogenous sample into different conformational states and to reach subnanometer resolution such that folding of the nascent chain into secondary structure elements can be directly visualized. With improved cryo‐electron tomography and correlative light microscopy and EM, it will be possible to visualize ribosomal complexes in their cellular context. WIREs RNA 2012, 3:429–441. doi: 10.1002/wrna.119This article is categorized under:

RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry
RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications
Translation > Ribosome Structure/Function