bluuebunny/crossref_metadata_2025_split huggingface dataset:
Saturation of the magnetorotational instability at large Elsasser number
Authors: Jamroz B. , Julien K. , Knobloch E. 
Published: September 2008

AbstractThe magnetorotational instability is investigated within the shearing box approximation in the large Elsasser number regime. In this regime, which is of fundamental importance to astrophysical accretion disk theory, shear is the dominant source of energy, but the instability itself requires the presence of a weaker vertical magnetic field. Dissipative effects are weaker still but not negligible. The regime explored retains the condition that (viscous and ohmic) dissipative forces do not play a role in the leading order linear instability mechanism. However, they are sufficiently large to permit a nonlinear feedback mechanism whereby the turbulent stresses generated by the MRI act on and modify the local background shear in the angular velocity profile. To date this response has been omitted in shearing box simulations and is captured by a reduced pde model derived here from the global MHD fluid equations using multiscale asymptotic perturbation theory. Results from numerical simulations of the reduced pde model indicate a linear phase of exponential growth followed by a nonlinear adjustment to algebraic growth and decay in the fluctuating quantities. Remarkably, the velocity and magnetic field correlations associated with these algebraic growth and decay laws conspire to achieve saturation of the angular momentum transport. The inclusion of subdominant ohmic dissipation arrests the algebraic growth of the fluctuations on a longer, dissipative time scale. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Can turbulent plane‐shear flows support large‐scale dynamos?
Authors: Kitchatinov L. L. 
Published: September 2008

AbstractTurbulent plane‐shear flow is found to show same basic effects of mean‐fieldMHD as rotating turbulence. In particular, the mean electromotive force (EMF) includes highly anisotropic turbulent diffusion and alpha‐effect. Only magnetic diffusion remains for spatially‐uniform turbulence. The question is addressed whether in this case a self‐excitation of a magnetic field by so‐called sher‐current dynamo is possible and the quasilinear theory provides a negative answer. The streamaligned component of the EMF has the sign opposite to that required for dynamo. If, however, the turbulence is not uniform across the flow direction then a dynamo‐activeα‐effect emerges. The critical magnetic Reynolds number for the alpha‐shear dynamo is estimated to be slightly above ten. Possibilities for cross‐checking theoretical predictions with MHD experiments are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Results of a modified PROMISE experiment
Authors: Stefani F. , Gerbeth G. , Gundrum Th. , Szklarski J. , Rüdiger G. , Hollerbach R. 
Published: September 2008

AbstractThe PROMISE experiment relies on the fact that the critical Reynolds number for the appearance of the magnetorotational instability (MRI) in liquid metal flows drastically decreases when the purely axial magnetic field is replaced by a helical one. We report the results of a modified version of this experiments in which the radial electrical boundary conditions are changed. Special focus is laid on the role of the radial jet region where the two Ekman vortices from the top and the bottom meet each other. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Furfural: Hemicellulose/xylosederived biochemical
Authors: Mamman Ajit Singh , Lee Jong‐Min , Kim Yeong‐Cheol , Hwang In Taek , Park No‐Joong , Hwang Young Kyu , Chang Jong‐San , Hwang Jin‐Soo 
Published: September 2008

AbstractHemicellulose, the second, most common polysaccharide in nature constitutes approximately 20—35% of lignocellulosic biomass. Effective utilization of biomass, hitherto underutilized, is gaining tremendous importance for the production of energy, fuels, and chemicals. Amongst the vast array of chemicals derived from lignocellulosics, furfural is the key chemical that finds wide applications in oil refining, plastics, pharmaceutical and agrochemical industries. There is no synthetic route for the production of furfural. A few conventional technologies currently in practice for its separation and subsequent isolation are appropriately reviewed. Major disadvantages associated with processes currently used for the production of furfural based on acid‐catalyzed hydrolysis have been discussed. A need to develop a process which is devoid of all the shortcomings associated with conventional process is emphasized. Several important aspects of chemistry underlying the acid hydrolysis of xylose are discussed. The importance of myriad pre‐treatment steps involved to surmount the physical and chemical barriers and to liberate xylose from the confines of acid‐resistant layer of lignin has been emphasized. New developments in the production of furfural from cyclodehydration of xylose using solid acid catalysts in the recent past have been reviewed appropriately in present communication. Finally, the production of furfural and furfuryl alcohol, their domestic market and export in China deserve some coverage and therefore have appropriately been discussed as well. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd
Intraneural ganglion cyst: A 200‐year‐old mystery solved
Authors: Spinner Robert J. , Vincent Jean‐François , Wolanskyj Alexandra P. , Scheithauer Bernd W. 
Published: September 2008

AbstractWe describe the first reported case of an intraneural ganglion cyst, an ulnar (“cubital”) intraneural cyst, which, on literature review, dated to 1810. For over 80 years, its original brief description by Beauchêne was wrongly attributed to Duchenne, effectively making the reference and specimen inaccessible to scrutiny. Fortunately, the intact cyst had been safely housed in the Musée Dupuytren, Paris, France, thus permitting its examination. Although originally described as a “serous” cyst, our present understanding of the anatomy of the ulnar nerve and of peripheral nerve pathology allowed us to reinterpret it as a mucin‐filled, elbow‐level, ulnar intraneural ganglion cyst. In addition to its description as a fusiform cystic enlargement of the nerve, we documented similar enlargement of a lumen‐bearing branch, the articular branch at the level of the elbow. Based on our assessment of the specimen and with a modern perspective, we concluded that the origin of the cyst was from the postero‐medial aspect of the elbow joint and that its fluid content, having dissected through a capsular defect, followed the path of the articular branch into the parent ulnar nerve. The purpose of this report is to clarify historical misconceptions regarding the pathogenesis of this controversial entity. Clin. Anat. 21:611–618, 2008. © 2008 Wiley‐Liss, Inc.
Structure, Magnetic Properties, Polarized Neutron Diffraction, and Theoretical Study of a Copper(II) Cubane
Authors: Aronica Christophe , Chumakov Yurii , Jeanneau Erwann , Luneau Dominique , Neugebauer Petr , Barra Anne‐Laure , Gillon Béatrice , Goujon Antoine , Cousson Alain , Tercero Javier , Ruiz Eliseo 
Published: September 2008

AbstractThe paper reports the synthesis, X‐ray and neutron diffraction crystal structures, magnetic properties, high field–high frequency EPR (HF‐EPR), spin density and theoretical description of the tetranuclear CuII complex [Cu4L4] with cubane‐like structure (LH2=1,1,1‐trifluoro‐7‐hydroxy‐4‐methyl‐5‐aza‐hept‐3‐en‐2‐one). The simulation of the magnetic behavior gives a predominant ferromagnetic interaction J1 (+30.5 cm−1) and a weak antiferromagnetic interaction J2 (−5.5 cm−1), which correspond to short and long Cu–Cu distances, respectively, as evidence from the crystal structure (ℋ︁=−${{{}\mathrel{\mathop{\sum{}}\limits_{i\char62 j}}{}}}$2JijŜiŜj). It is in agreement with DFT calculations and with the saturation magnetization value of an S=2 ground spin state. HF‐EPR measurements at low temperatures (5 to 30 K) provide evidence for a negative axial zero‐field splitting parameter D (−0.25±0.01 cm−1) plus a small rhombic term E (0.025±0.001 cm−1, E/D = 0.1). The experimental spin distribution from polarized neutron diffraction is mainly located in the basal plane of the CuII ion with a distortion of yz‐type for one CuII ion. Delocalization on the ligand (L) is observed but to a smaller extent than expected from DFT calculations.
A Dinuclear Iron Complex Based on Parallel Malonate Binding Sites: Cooperative Activation of Dioxygen and Biomimetic Ligand Oxidation
Authors: Siewert Inke , Limberg Christian , Demeshko Serhiy , Hoppe Elke 
Published: September 2008

AbstractA ligand that offers two parallel malonate binding sites linked by a xanthene backbone, namely, Xanthmal2−, has been utilised to synthesise dinuclear FeII complex [Fe2(Xanthmal)2] (1). The reactivity of 1 in contact with O2 was investigated at −40 °C and room temperature. After activation of O2 through interaction with both iron centres the ligand is oxidised: at the Cα position monooxygenation and peroxide formation occur, partially accompanied by CC bond cleavage to yield α‐keto ester groups. To reveal mechanistic details investigations concerning 1) peroxide decomposition, 2) the reactivity of a corresponding mononuclear complex, 3) the influence of monooxygenation of the ligand on the reactivity and 4) product formation in dependence on time were carried out. The results can be explained by postulating formation of high‐valent Fe intermediates and ligand‐to‐metal electron transfer, and the mechanistic scheme derived includes several steps that mimic the (suggested) functioning of non‐heme iron enzymes. In agreement with this proposal, ligand oxidation can also be performed catalytically. Furthermore, we show that via a competitive route [(Xanthmal)2Fe2O] (2) is formed, which is unreactive towards O2 and thus is a dead end with respect to ligand oxidation. Both compounds 1 and 2 were fully characterised, and their properties are discussed.
Determination of the Electrophilicity Parameters of Diethyl Benzylidenemalonates in Dimethyl Sulfoxide: Reference Electrophiles for Characterizing Strong Nucleophiles
Authors: Kaumanns Oliver , Lucius Roland , Mayr Herbert 
Published: September 2008

AbstractThe second‐order rate constants of the reactions of nine substituted diethyl benzylidenemalonates 1 a–i with the carbanions 2 a–e have been determined spectrophotometrically in dimethyl sulfoxide (DMSO). Product studies show that the nucleophiles attack regioselectively at the electrophilic CC double bond of the Michael acceptors to form the carbanionic adducts 4. The correlation log k(20 °C)=s(N+E) allows the determination of the electrophilicity parameters E for the electrophiles 1 a–i from the rate constants determined in this work and the previously published N and s parameters for the nucleophiles 2 a–e. The electrophilicities E for compounds 1 a–i cover a range of six units (−17.7>E>−23.8) and correlate excellently with Hammett's substituent constants σp. The title compounds are roughly ten orders of magnitude less reactive than analogously substituted benzylidene Meldrum's acids, their cyclic analogues. Due to their low reactivities, compounds 1 a–i are suitable reference electrophiles for determining the reactivities of highly reactive nucleophiles, such as carbanions with 16<N<30.
First Principles Investigation of Noncovalent Complexation: A [2.2.2]‐Cryptand Ion‐Binding Selectivity Study
Authors: Su Joe W. , Burnette Ronald R. 
Published: September 2008

AbstractA first principles methodology, aimed at understanding the roles of molecular conformation and energetics in host–guest binding interactions, is developed and tested on a system that pushes the practical limits of ab initio methods. The binding behavior between the [2.2.2]‐cryptand host (4,7,13,16,21,24‐hexaoxa‐1,10‐diaza‐bicyclo[8.8.8]hexacosane) and alkali metal cations (Li+, Na+, and K+) in gas, water, methanol, and acetonitrile is characterized. Hartree–Fock and density functional theory methods are used in concert with crystallographic information to identify gas phase, energy‐minimized conformations. Gas phase free energies of binding, with vibrational contributions, are compared to solution‐state binding constants through relative binding selectivity analysis. Calculated relative binding free energies qualitatively correlated with solution state experiments only after gas phase metal desolvation is considered. The B3LYP exchange–correlation functional improves theoretical correlations with experimental relative binding free energies. The relevance of gas phase calculations towards understanding binding in condensed phases is discussed. Natural bond orbital methods highlights previously unidentified intramolecular and intermolecular M+(222) chemistries, such as an intramolecular n′O→σ*CH hydrogen bond.
Metamorphosis and adult development of the mushroom bodies of the red flour beetle, Tribolium castaneum
Authors: Zhao X. , Coptis V. , Farris S. M. 
Published: September 2008

AbstractThe insect mushroom bodies play important roles in a number of higher processing functions such as sensory integration, higher level olfactory processing, and spatial and associative learning and memory. These functions have been established through studies in a handful of tractable model systems, of which only the fruit fly Drosophila melanogaster has been readily amenable to genetic manipulations. The red flour beetle Tribolium castaneum has a sequenced genome and has been subject to the development of molecular tools for the ready manipulation of gene expression; however, little is known about the development and organization of the mushroom bodies of this insect. The present account bridges this gap by demonstrating that the organization of the Tribolium mushroom bodies is strikingly like that of the fruit fly, with the significant exception that the timeline of neurogenesis is shifted so that the last population of Kenyon cells is born entirely after adult eclosion. Tribolium Kenyon cells are generated by two large neuroblasts per hemisphere and segregate into an early‐born δ lobe subpopulation followed by clear homologs of the Drosophila γ, α′/β′ and α/β lobe subpopulations, with the larval‐born cohorts undergoing dendritic reorganization during metamorphosis. BrdU labeling and immunohistochemical staining also reveal that a proportion of individual Tribolium have variable numbers of mushroom body neuroblasts. If heritable, this variation represents a unique opportunity for further studies of the genetic control of brain region size through the control of neuroblast number and cell cycle dynamics. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
Adolescent development of neuron structure in dentate gyrus granule cells of male syrian hamsters
Authors: Zehr Julia L. , Nichols Liana R. , Schulz Kalynn M. , Sisk Cheryl L. 
Published: September 2008

AbstractHippocampal function, including spatial cognition and stress responses, matures during adolescence. In addition, hippocampal neuron structure is modified by gonadal steroid hormones, which increase dramatically at this time. This study investigated pubertal changes in dendritic complexity of dentate gyrus neurons. Dendrites, spines, and cell bodies of Golgi‐impregnated neurons from the granule cell layer were traced in pre‐, mid‐, and late‐pubertal male Syrian hamsters (21, 35, and 49 days of age). Sholl analysis determined the number of intersections and total dendritic length contained in concentric spheres set at 25‐μm increments from the soma. Spine densities were quantified separately in proximal and distal segments of a subset of neurons used for the Sholl analysis. We found that the structure of neurons in the lower, but not upper, blade of the dentate gyrus changed during adolescence. The lower, infrapyramidal blade showed pruning of dendrites close to the cell body and increases in distal dendritic spine densities across adolescence. These data demonstrate that dentate gyrus neurons undergo substantial structural remodeling during adolescence and that patterns of maturation are region specific. Furthermore, these changes in dendrite structure, which alter the electrophysiological properties of granule cells, are likely related to the adolescent development of hippocampal‐dependent cognitive functions such as learning and memory, as well as hippocampus‐mediated stress responsivity. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
Dual inhibition of proteasomal and lysosomal proteolysis ameliorates autoimmune central nervous system inflammation
Authors: Fissolo Nicolas , Kraus Marianne , Reich Michael , Ayturan Miriam , Overkleeft Herman , Driessen Christoph , Weissert Robert 
Published: September 2008

AbstractMultiple sclerosis (MS) is a detrimental disease of the central nervous system (CNS) leading to long‐term disability. In the course of animal models of multiple sclerosis (experimental autoimmune encephalomyelitis), we find enhanced activity of proteasome subunits b1i, b2, b2i and b5 in the CNS. We demonstrate that pharmacological inhibition of the proteasome by bortezomib ameliorates experimental autoimmune encephalomyelitis in mice and rats in prophylactic and therapeutic treatment with reduced numbers of T‐cells secreting proinflammatory cytokines. The anti‐inflammatory effect of proteasome inhibition was accompanied by reduced NF‐jB activity in the CNS and lymphoid organs. The combined inhibition of proteasomes and lysosomal proteases involved in major histocompatibility complex II antigen presentation further improved therapeutic efficacy. We suggest proteasome inhibition alone or in combination with inhibition of lysosomal proteases as a novel therapeutic strategy against inflammation‐induced neurodegeneration in the CNS. We demonstrate the impact of the proteasome and lysosomal proteases on development of autoimmunity.
Geoadditive models for the analysis of the spatial distribution of soil salinity in a Sardinia coastal area
Authors: Cafarelli Barbara , Pollice Alessio 
Published: September 2008

AbstractThe use of geoadditive models is proposed to analyse the spatial distribution of the sodium absorption ratio (SAR) of a citrus groves cultivated area, in order to ascertain the factors influencing its extreme salinization. Geoadditive models are considered as an evolution of universal kriging, allowing explicit consideration of the linear and nonlinear relations with relevant explanatory variables as well as the spatial correlation described by a standard spatial autocorrelation function. Copyright © 2008 John Wiley & Sons, Ltd.
Analytical ecological epidemiology: exposure–response relations in spatially stratified time series
Authors: Scherb Hagen , Voigt Kristina 
Published: September 2008

AbstractAn important task of environmental research is the investigation of a possible causal relationship between exposure and the frequency of a biologic trait. Major industrial accidents provide examples where the exposure status of large populations may change considerably within relatively short time intervals of days or weeks (e.g. Seveso herbicide plant explosion, Chernobyl Nuclear Power Plant catastrophe). Therefore, purely temporal change‐points may be tested in time series of appropriate public health indicators (e.g. mortality, morbidity, sex ratio at birth). If, in addition, the spatial contamination is strong and variable enough and can be identified with sufficient precision at the level of regional units (e.g. districts), then a spatial‐temporal approach makes sense. This essentially means that a global time trend model is adjusted for region‐specific trend functions, allowing for local or global temporal jumps or broken sticks (change‐points) at certain points in time. The local jump heights may be tested for associations with local exposure (exposure–response relation), and all other characteristics in the data that vary with locality and in time are automatically accounted for, thus minimizing confounding. Spatial‐temporal approaches may help to strengthen the evidence of possible causal relationships. As an example, the human sex ratio at birth in several European countries before and after the Chernobyl Nuclear Power Plant accident was investigated. A long‐term chronic impact of radioactive fallout on the secondary sex ratio has been found. Copyright © 2008 John Wiley & Sons, Ltd.
Europe 1992: The European commission's policy in telecommunications
Authors: Schulte‐Braucks Reinhard 
Published: September 2008

AbstractThis article deals with both the principles of the Green Paper on telecommunications and the current situation of its implementation. It presents the measures necessary for the completion of the Community's internal market and the liberalization of the markets for telecommunications terminal equipment and services. Moreover, it describes the European Commission's initiatives in the field of public procurement and Community‐wide telecommunications infrastructures.
A modification of the predictive analysis for the multiple site diversity performance taking into account the stratified rain
Authors: Kanellopoulos John , Ventouras Spyros 
Published: September 2008

AbstractMultiple site diversity systems are foreseen for earth to satellite paths operating at frequencies above 10 GHz in localities with high rain‐induced attenuation. A recently suggested model for the prediction of diversity performance is properly modified by considering also the stratified type of rain. The modified method uses the assumption of lognormal unconditional distribution of rainfall for the location under consideration. Numerical results are applied to several satellite systems operating in various locations in the United States and Italy. Some useful conclusions are deduced.
Comparison of different facsimile data compression methods for text, graphics and halftone documents
Authors: Böhm Wolfgang , Hartmann Ralf , Ruske Günther 
Published: September 2008

AbstractIn order to store digital image data in a pel‐by‐pel representation a huge amount of storage capacity is necessary. For example a DIN A4 page scanned with a resolution of 300 dpi (dots per inch) needs about 1.1 Mbyte storage capacity in binary representation.This paper deals with various methods to compress binary image data. The focus is to discuss their suitability for archiving usual business documents made up of text, graphics and halftone segments.The two‐dimensional CCITT group 4 recommendation is compared with an adaptive prediction algorithm and a Classified Pel‐Pattern (CLAP) method. For the latter a very efficient systematic code is given. The Classified Pel‐Pattern algorithm achieves the best data compression but at the cost of high complexity. Compressing documents scanned with a resolution of 300 dpi the measured compression ratio is between 1.3–2.5 (halftone pictures) and 50 (line art). Considering only text and graphic documents the recommendation of the CCITT is 5–10% worse but complexity is significantly less. However, it is found that this methods show unsatisfactory results applied to halftone pictures.