bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoreflectance spectroscopy for the qualification of GaAsSb alloys introduced in ultrafast heterojunction bipolar transistors on InP
Authors: Chouaib Houssam , Bru‐Chevallier Catherine , Apostoluk Aleksandra , Rudno‐Rudzinski Wojciech , Pelouard Jean‐Luc , Lijadi Melania , Bove Philippe
Published: March 2009

GaAsSb is an important III–V semiconductor ternary alloy which is currently used as the thin base layer in high speed InP Heterojunction Bipolar Transistors (HBT). Up to now, very little is known about physical properties of GaAsSb alloys, such as surface Fermi level pinning and Schottky barrier heights with different contact metals. However such parameters impact directly the cut‐off frequency of HBT devices. Photoreflectance spectroscopy is applied to specific samples differing by their Sb concentration. The exploitation of Franz–Keldysh Oscillations (FKO) spectra allows determining the Fermi level pinning at the free surface of GaAsSb as a function of the alloy composition. Micro‐electroreflectance spectroscopy is also applied to Schottky diodes performed on the same structures, with Ti deposited at the GaAsSb surface. The Schottky barrier height between GaAsSb and Ti is derived from the FKO system recorded in the micro‐electroreflectance spectra. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The magnetic properties of DyFe2Si2 and its crystal‐field levels
Authors: Liu Z.‐S. , Diviš M. , Sechovský V.
Published: March 2009

We used a two‐ion model to derive analytic formulas for the magnetization of DyFe2Si2 with its lowest crystal‐field (CF) states in the presence of an external field exerted in the easy c and hard a directions, respectively, and then evaluated the initial spontaneous magnetization and the Néel temperature of the magnet with the formulas obtained. In comparison with experimental data, our theoretical results suggest that the magnetic process along the easy axis is dominated by the two lowest CF states in the temperature range at least up to 20 K, but the magnetic behaviour in the hard a direction is governed by the six states of the three lowest CF doublets. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Highly nonlinear phenomena of self‐organization of quasi‐two‐dimensional electron gas in high magnetic and electric fields
Authors: Maglevanny I. I.
Published: March 2009

The transverse electric field Ey that appears in lateral superlattices (2SLs) under Hall‐measurement conditions, i.e. in the presence of a longitudinal applied electric field Ex and applied magnetic field H normal to the SL plane (H ∥ OZ) is calculated. In contrast to previous works devoted to this problem both applied electric and magnetic fields are treated as control parameters. By introducing the generalized function of entropy production (the synergetic potential) the kinetic behavior of a quasi‐two‐dimensional nonequilibrium electron gas is investigated from the viewpoint of self‐organization and catastrophe theory. The field Ey contains both the Hall field and the spontaneous transverse electric field that exists without H. The magnetoresistance caused by the appearance of a spontaneous transverse EMF is investigated. Spontaneous transverse EMF, current–voltage characteristics and magnetoresistance are multivalued and sign‐changing functions of applied electric and magnetic fields. From the model computer simulations the observed multistability exhibits a large difference in the behavior of the system in high magnetic fields as compared to low one. The novel nonlinear effects such as first‐order nonequilibrium phase transitions and hysteresis, induced by magnetic field are predicted. As the magnetic field is increased the nonlinear behaviors show self‐organized hierarchical complexity, which manifests itself in fractalization of bifurcation set, whose self‐similar fine structure leading to fractal‐like folds of critical manifold sheets, resulting in fuzzy bifurcations, was discovered. Complex nonlinear behaviors including macrostate crisis and chaotic‐looking intermittency of Hall‐effect characteristics were discovered in limited narrow ranges of the control parameter space. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient moist physics schemes for data assimilation. II: Deep convection
Authors: Stiller O.
Published: March 2009

The development of a cost‐effective convection scheme for a linear 4D‐Var model is described. The very noisy and unsteady behaviour of the Met Office's nonlinear mass‐flux convection scheme motivated an approach in which the linear model is designed to correspond to its nonlinear counterpart only in a time‐average sense. Technically this is implemented in a numerically efficient way by pre‐processing (mainly time‐averaging) the linear scheme's main input files outside the linear model. The new linear scheme includes only two terms from the nonlinear parametrization's sensitivities; one originates from the subsidence part, while the other, the dominant term, involves convective mass‐flux perturbations resulting from the convective available potential energy (CAPE) closure relationship. Including these terms required error mitigation measures, partially to compensate for neglected terms that in some situations have the opposite sign to the represented terms. Measures were also taken to increase the scheme's stability as well as its numerical efficiency. The introduction of this scheme into the Met Office numerical weather prediction (NWP) system led to clear improvements of the forecast skill. Linearization test results show that the new scheme improves the match between linear and nonlinear models. Consistent with its statistical interpretation, precipitation increments of the linear scheme show a reasonable correlation to their nonlinear counterparts only if the nonlinear precipitation is averaged over time intervals of several hours. ©Crown Copyright 2009. Reproduced with the permission of HMSO. Published by John Wiley & Sons Ltd.
The local ETKF and SKEB: Upgrades to the MOGREPS short‐range ensemble prediction system
Authors: Bowler Neill E. , Arribas Alberto , Beare Sarah E. , Mylne Kenneth R. , Shutts Glenn J.
Published: March 2009

The Met Office has been routinely running a short‐range global and regional ensemble prediction system (EPS) since the summer of 2005. This article describes a major upgrade to the global ensemble, which affected both the initial condition and model uncertainty perturbations applied in that ensemble. The change to the initial condition perturbations is to allow localization within the ensemble transform Kalman filter (ETKF). This enables better specification of the ensemble spread as a function of location around the globe. The change to the model uncertainty perturbations is the addition of a stochastic kinetic energy backscatter scheme (SKEB). This adds vorticity perturbations to the forecast in order to counteract the damping of small‐scale features introduced by the semi‐Lagrangian advection scheme.

Verification of ensemble forecasts is presented for the global ensemble system. It is shown that the localization of the ETKF gives a distribution of the spread as a function of latitude that better matches the forecast error of the ensemble mean. The SKEB scheme has a substantial effect on the power spectrum of the kinetic energy, and with the scheme a shallowing of the spectral slope is seen in the tail. A k−5/3 slope is seen at wavelengths shorter than 1000 km and this better agrees with the observed spectrum. The local ETKF significantly improves forecasts at all lead times over a number of variables. The SKEB scheme increases the rate of growth of ensemble spread in some variables, and improves forecast skill at short lead times. ©Crown Copyright 2009. Reproduced with the permission of HMSO. Published by John Wiley & Sons Ltd.
Ensemble transform Kalman filter perturbations for a regional ensemble prediction system
Authors: Bowler Neill E. , Mylne Kenneth R.
Published: March 2009

The Met Office has been routinely running a short‐range ensemble prediction system since the summer of 2005. This system consists of two component ensembles, a global ensemble that provides lateral boundary conditions to a regional ensemble. The global ensemble calculates the initial condition perturbations using a local version of the ensemble transform Kalman filter (ETKF). This article details tests of an ETKF run specifically for the regional ensemble.

The perturbations using the ETKF for the regional ensemble contain more detail on small scales and less power on large scales. This extra small‐scale detail persists for less than 18 h. These perturbations are overall smaller than the ones derived from the global ensemble, since they have been explicitly scaled to match the average error of the ensemble mean forecast at T + 6 h. Aside from the difference in the overall scaling of the perturbations, the skill of the two ensembles is very similar, with slightly higher skill being seen when the perturbations are derived from the global ensemble. The ETKF for the regional ensemble was implemented during May 2007. This change has recently been reversed, following these results.

These comparisons may shed some light on whether the regional ensemble is providing a ‘dynamical downscaling’ of the global ensemble, or unique information of its own. In these tests the ensemble run with perturbations from the global ensemble was slightly more skilful than the regional perturbations ensemble, indicating that improving on dynamical downscaling is likely to be difficult. ©Crown Copyright 2009. Reproduced with the permission of HMSO. Published by John Wiley & Sons Ltd.
Density Functional Theory‐based Quantitative Structure Activity Relationship (QSAR) Study of Alkanol and Alkanthiol Derivatives
Authors: Mehdipour Ahmad Reza , Safarpour Mohammad Ali , Taghavi Fariba , Jamali Maryam
Published: March 2009

The usefulness of the quantum chemical descriptors and a novel group of descriptors called quantum topological molecular similarity (QTMS) indices, calculated at the level of density functional theory (DFT) using 6‐311++G** basis set for QSAR study of anesthetic drugs was examined. A data set containing 24 alkanol and alkanethiol derivatives with known activity was used. Three types of molecular descriptors including QTMS, chemical and quantum chemical was used to derive a quantitative relationship between the anesthetic potency and structural properties. MLR and GA‐PLS were employed to model the relationships between molecular descriptors and biological activity of molecules. Some multiparametric equations containing three descriptors with appropriate statistical qualities were obtained Also, GA‐PLS regression was used to model the structure‐activity relationships more accurately. The results showed that the results obtained by GA‐PLS are similar to MLR and confirmed that hydroxyl group might be the most important region in anesthetic activity of alkanols and akanethiols.
Novel Pirinixic Acids as PPARα Preferential Dual PPARα/γ Agonists
Authors: Zettl Heiko , Dittrich Michaela , Steri Ramona , Proschak Ewgenij , Rau Oliver , Steinhilber Dieter , Schneider Gisbert , Lämmerhofer Michael , Schubert‐Zsilavecz Manfred
Published: March 2009

Pirinixic acid is a moderate agonist of both the alpha and the gamma subtype of the peroxisome proliferator activated receptor (PPAR). Previously, we have shown that α‐alkyl substitution leads to balanced low micromolar‐active dual agonists of PPARα and PPARγ. Taking α‐hexyl pirinixic acid as a new scaffold, we further optimized PPAR activity by enlargement of the lipophilic backbone by substituting the 2,3‐dimethylphenyl with biphenylic moieties. Such a substitution pattern had only minor impact on PPARγ activity but further increased PPARα activity leading to nanomolar activities. Supporting docking studies proposed that the (R)‐enantiomer should fit the PPARα ligand‐binding pocket better and thus be more active than the (S)‐enantiomer. Single enantiomers of selected active analogues were then prepared by enantio‐selective synthesis and enantio‐selective preparative HPLC, respectively. Biological data for the distinct enantiomers fully corroborated the docking experiments and substantiate a stereochemical impact on PPAR activation.
Dynamic update of Java applications—balancing change flexibility vs programming transparency
Authors: Gregersen Allan Raundahl , Jørgensen Bo Nørregaard
Published: March 2009

The ability to dynamically change the behavior of an application is becoming an important issue in contemporary rich client software development. Not only can programmers benefit from dynamic updates during the development of concurrent applications where recreation of complex application states can be avoided during test and debugging but also at post‐deployment time where applications can be updated transparently without going through the well‐known halt, redeploy and restart scheme. In this paper, we explain how our dynamic update framework achieves transparent dynamic updates of running Java applications while guaranteeing both type and thread safety. A novel feature of our approach is that it supports full redefinition of classes by allowing changes to the type hierarchy. Our approach is based on a lightweight runtime system, which is injected into an application via bytecode transformations at class loading. We show how our approach can add dynamic update capabilities to rich client development by integrating it with the NetBeans rich client platform. Performance experiments on our NetBeans implementation show that the overhead of our approach is low when applied to component application programming interface classes. To the best of our knowledge no other existing approach achieves the same level of low overhead and programming transparency. Copyright © 2009 John Wiley & Sons, Ltd.
Upgrading mainland Europe's oldest iron suspension footbridge
Authors: Wouters Ine , Bouw Michael de , Adriaenssens Sigrid , Verdonck Ann
Published: March 2009

Wissekerke castle park in Belgium contains mainland Europe's oldest remaining iron suspension bridge (1824). In 1989, after years of neglect, the Kruibeke town council bought the castle, park and finally, in 2006, the bridge. The Architectural Engineering Lab of the Vrije Universiteit Brussel (æ‐lab) was consulted to put the refurbishment on the right lines and to check whether this bridge can stand the shift in function from private to public.

This paper places the pedestrian bridge within the framework of 19th century bridge construction, determines its historical value, characterizes the used materials by metallographic methods combined with tensile and hardness tests, re‐analyses the structure, proposes strengthening strategies and concludes with a renovation proposal that preserves all of the authentic elements, causes the least visual impact, is durable and guarantees continued public use.
A Simple Mechanochemical Route to Layered Double Hydroxides: Synthesis of Hydrotalcite‐Like Mg‐Al‐NO3‐LDH by Manual Grinding in a Mortar
Authors: Ay Ahmet N. , Zümreoglu‐Karan Birgül , Mafra Luis
Published: March 2009

Hydrotalcite‐like Mg‐Al‐NO3‐layered double hydroxide (LDH) was successfully prepared in a mortar by manually grinding the hydrated magnesium and aluminum nitrate salts with sodium hydroxide. Various techniques, including XRD, MAS NMR, FTIR, SEM; thermogravimetric and differential thermal analyses (TGA,DTA), surface area and zeta potential measurements were used to establish a correlation between the LDH samples prepared in the mortar and by co‐precipitation. The LDH prepared in the mortar showed all the characteristics of a layered structure but with a lower crystallinity. This product was tested for its anion exhange property with tetraborate anions and 52 % of the theoretical exchange capacity was reached. The mortar route does not require heating/refluxing treatment, CO2‐free atmosphere and solvent as in the conventional preparation methods and allows obtaining LDHs in a short reaction time.
[Fe(C6H14N2)2][Sb6S10] – Using a Transition Metal Complex Acting as a Pillar for the Generation of a Three‐dimensional Thioantimonate(III) Network
Authors: Kiebach Ragnar , Warratz Ralph , Näther Christian , Bensch Wolfgang
Published: March 2009

The new three‐dimensional thioantimonate [Fe(C6H14N2)2][Sb6S10] was obtained under solvothermal conditions. The compound crystallizes in space group P with a = 6.174(4), b = 9.679(2), c = 12.772(3) Å, α = 72.08(3), β = 88.15(3), γ = 89.51(3)°, Z = 2. Trigonal pyramidal [SbS3] units and [SbS4] groups are joined to form a two‐dimensional [Sb6S10]2– layer. The in‐situ formed [Fe(C6H14N2)2]2+ complexes act like pillars joining the layers into a three‐dimensional framework through Fe–S bonds. The Fe–S bond lengths are long which may be caused by a pronounced Jahn–Teller distortion. The optical bandgap of 2.0 eV is in agreement with the brownish color of the compound. The Mössbauer spectrum shows a doublet with an isomer shift typical for Fe2+ in the high spin state. In the Raman spectrum the Sb–S stretching modes of the [SbS3] and [SbS4] groups can be distinguished. Upon heating in nitogen the compound is decomposed in one step yielding Sb2S3 and FeSb2S4.
[Cu(H2O)(C5H14N2)2][VO3]2 – A Metavanadate Containing Right‐ and Left‐Handed Helical Chains
Authors: Wutkowski Adam , Näther Christian , Bensch Wolfgang
Published: March 2009

The new metavanadate [Cu(H2O)(C5H14N2)2][VO3]2 (C5H14N2 is 2,2‐dimethylpropyldiamine) (1) was synthesized under solvothermal conditions. The compound crystallizes in the rhombohedral space group R3m with a = 28.6984(15), c = 6.4309(3), V = 4586.9(4) Å3, Z = 9. The main structural motifs are helical metavanadate {VO3}nn– chains made by corner‐sharing [VO4]3– tetrahedra and [Cu(H2O)(C5H14N2)2]2+ complexes with the Cu2+ ion being in a distorted square‐pyramidal coordination environment. The complexes are located between left‐ and right‐handed metavanadate chains.The arrangement of the chains and the [Cu(H2O)(C5H14N2)2]2+ complexes generates channels with liphophilic walls running along [001]. It seems that the orientation of the [Cu(H2O)(C5H14N2)2]2+ moieties is fixed between the metavanadate chains by strong hydrogen bonding interactions. This special arrangement prevents Cu–O bond formation as observed in many Cu2+ containing metavanadate compounds. The compound decomposes in at least three steps. The optical bandgap was determined to 3.04 eV.
Hydrothermal Synthesis of Chiral Metal(II) Phosphinates Derived from Camphor
Authors: Beckmann Jens , Duthie Andrew , Rüttinger Roman , Schwich Torsten
Published: March 2009

The diastereoselective synthesis of bis(3‐endo‐camphoryl)phosphinic acid (1) and its 2‐bornen‐2‐yl ester 2 from the reaction of lithium camphor enolate with phosphorus trichloride and the hydrothermal synthesis of three chiral molecular metal(II) phosphinates of the type M(O2PR2)2·2R2P(O)OH [M = Co (3); Ni (4); Pb (5); R = 3‐endo‐camphoryl] from the reaction of 1 with metal(II) acetates or nitrates is described. The molecular structures of 1–5 are reported.
BaAuP and BaAuAs, Synthesis via Disproportionation of Gold upon Interaction with Pnictides as Bases
Authors: Nuss Jürgen , Jansen Martin
Published: March 2009

Gold disproportinates in the presence of the Zintl phases Ba3P2 or Ba3As2 forming BaAuP and BaAuAs, respectively, and BaAu2. The air and moisture sensitive ternary compounds crystallise in the ZrBeSi type of structure, an ordered variant of AlB2: BaAuP (P63/mmc; a = 440.68(6) pm; c = 899.8(2) pm; R1 = 0.0237; 183 independent reflections); BaAuAs (P63/mmc; a = 453.53(5) pm; c = 902.7(1) pm; R1 = 0.0255; 168 independent reflections). Both compounds, which are accessible as pure phases by reacting BaP or BaAs with gold, can be classified as poor metallic conductors.
A Novel Expansion Mode of Polyoxovanadate Clusters: Synthesis, Crystal Structure and Properties of {[Cu(H2O)(C5H14N2)2]2[V16O38(Cl)]}·4(C5H16N2)
Authors: Wutkowski Adam , Näther Christian , Speldrich Manfred , Kögerler Paul , Bensch Wolfgang
Published: March 2009

The new polyoxovanadate (POV) compound {[Cu(H2O)(C5H14N2)2]2[V16O38(Cl)]}·4(C5H16N2) was synthesized under solvothermal conditions and crystallizes in the tetragonal space group I41/amd with a = 13.8679(6), c = 45.558(2) Å, V = 8761.7(7) Å3. The central structural motif is a {V16O38(Cl)} cluster constructed by condensation of 16 square‐pyramidal VO5 polyhedra. The cluster hosts a central Cl– anion. According to valence bond sum calculations, chemical analysis and magnetic properties the cluster anion may be formulated as [V15IVVVO38(Cl)]12–, i.e., only one vanadium atom is not reduced. To the best of our knowledge this is the first reported {V16O38(X)} cluster in this VIV:VV ratio. The presence of the two different vanadium oxidation states is clearly seen in the IR spectrum. An unusual and hitherto never observed structural feature is the binding mode between the [Cu(H2O)(C5H14N2)2]2+ complexes and the [V15IVVVO38(Cl)]12– anion. The Cu2+ ion binds to a μ2‐O atom of the cluster anion whereas in all other transition metal complex‐augmented POVs bonding between the transition metal cation and the anion occurs through terminal oxygen atoms of the POV. The magnetic properties are dominated by strong antiferromagnetic exchange interactions between the V4+ d1 centers, whereas the Cu2+ d9 cations are magnetically decoupled from the cluster anion. Upon heating, the title compound decomposes in a complex fashion.
Silver(I), Copper(I) and Copper(II) Complex of the New N,Se‐Chelate Ligand 2‐Phenylselenomethyl‐1H‐benzimidazole: Electrochemistry and Structure
Authors: Leboschka Markus , Sieger Monika , Sarkar Biprajit , Niemeyer Mark , Schurr Thilo , Fiedler Jan , Záliš Stanislav , Kaim Wolfgang
Published: March 2009

2‐Phenylselenomethyl‐1H‐benzimidazole (psbi) can form complexes in 2:1 ratio with coinage metal ions. Crystal structure analysis revealed a flattened metal coordination for [AgI(psbi)2](BF4) (1), approaching a distorted‐planar arrangement with weak Ag–Se bonds (d > 2.9 Å) and confirmed as energy minimum by DFT calculations. The typical Jahn–Teller system [CuII(psbi)2Cl2] (2) exhibits a planar CuN2Cl2 core with weak Se···Cu···Se axial ligation [3.2944(8) Å Cu···Se distance]. The oxygen‐sensitive compound [CuI(psbi)2](BF4) (3) exhibits electrochemically reversible oxidation in contrast to the silver(I) analogue 1.
Dissociating self-reported cognitive complaint from clinical insight in schizophrenia
Authors: Bayard Sophie , Capdevielle Delphine , Boulenger Jean-Philippe , Raffard Stéphane
Published: March 2009

Whereas new pharmacological treatments are developed for cognitive impairments in schizophrenia, self-assessment of cognitive dysfunctioning besides their objective validity could be of interest in evaluating patients' motivation to engage in rehabilitation program. Nevertheless insight into symptoms is severely impaired in schizophrenia and is negatively linked with poor compliance. But it is yet unknown if patients with poor insight into their symptoms could have some insight into their cognitive impairments. The aim of this study was to explore the relationships existing between the cognitive complaint and the level of awareness of the disease in patients with schizophrenia. A total of 101 patients with DSM-IV schizophrenia or schizoaffective disorder and 60 control participants were recruited. Insight was assessed using the Scale to assess Unawareness of Mental Disorder (SUMD) and cognitive complaint intensity was assessed with the Scale to Investigate Cognition in Schizophrenia (SSTICS). Participants with schizophrenia displayed the same level of cognitive complaint when compared to healthy controls. Strong correlations were observed between SSTICS total score and duration of illness, levels of depression and state anxiety. Patients with a good insight into the therapeutic effects achieved with medication expressed a more important cognitive complaint. No correlations were found between the four others SUMD insight dimensions and total SSTICS score. The partial overlap of insight into illness and cognitive complaint suggests that insight is modular in schizophrenia. Assessment of cognitive complaint and awareness of illness need to be assessed before engagement in rehabilitation program.
T0901317, an LXR agonist, augments PKA‐induced vascular cell calcification
Authors: Hsu Jeffrey J. , Lu Jinxiu , Huang Michael S. , Geng Yifan , Sage Andrew P. , Bradley Michelle N. , Tontonoz Peter , Demer Linda L. , Tintut Yin
Published: March 2009

We examined the effect of liver X receptor (LXR) agonists on vascular calcification, prevalent in atherosclerotic lesions. T0901317, an LXR agonist, augmented protein kinase A (PKA)‐induced mineralization and alkaline phosphatase (ALP) activity in aortic smooth muscle cells isolated from wild‐type, but not from Lxrβ
−/−mice. A six‐hour T0901317 treatment augmented the PKA‐induced expression of the phosphate transporter Pit‐1, a positive regulator of mineralization, suggesting a direct role. A ten‐day T0901317 treatment attenuated PKA‐induced expression of mineralization inhibitors, osteopontin and ectonucleotide pyrophosphatase/phosphodiesterase‐1, suggesting an indirect role. The effects of T0901317 were attenuated by inhibition of ALP, Pit‐1 and Rho‐associated kinase, but not by inhibition of PKA. These results suggest that T0901317‐augmented mineralization occurs downstream of PKA, involving both direct and indirect LXR‐mediated pathways.
Early mafic magmatism and crustal anatexis on the Isle of Rum: evidence from the Am Màm intrusion breccia
Authors: NICOLL GRAEME R. , HOLNESS MARIAN B. , TROLL VALENTIN R. , DONALDSON COLIN H. , HOLOHAN EOGHAN P. , EMELEUS C. HENRY , CHEW DAVID
Published: March 2009

The Rum Igneous Centre comprises two early marginal felsic complexes (the Northern Marginal Zone and the Southern Mountains Zone), along with the later central ultrabasic–basic layered intrusions. These marginal complexes represent the remnants of near-surface to eruptive felsic magmatism associated with caldera collapse, examples of which are rare in the North Atlantic Igneous Province. Rock units include intra-caldera collapse breccias, rhyolitic ignimbrite deposits and shallow-level felsic intrusions, as well the enigmatic ‘Am Màm intrusion breccia’. The latter comprises a dacitic matrix enclosing lobate basaltic inclusions (~1–15 cm) and a variety of clasts, ranging from millimetres to tens of metres in diameter. These clasts comprise Lewisian gneiss, Torridonian sandstone and coarse gabbro. Detailed re-mapping of the Am Màm intrusion breccia has shown its timing of emplacement as syn-caldera, rather than pre-caldera as previously thought. Textural analysis of entrained clasts and adjacent, uplifted country rocks has revealed their thermal metamorphism by early mafic intrusions at greater depth than their present structural position. These findings provide a window into the evolution of the early mafic magmas responsible for driving felsic magmatism on Rum. Our data help constrain some of the physical parameters of this early magma–crust interaction and place it within the geochemical evolution of the Rum Centre.
Sedimentary and volcano-tectonic processes in the British Paleocene Igneous Province: a review
Authors: BROWN DAVID J. , HOLOHAN EOGHAN P. , BELL BRIAN R.
Published: March 2009

Research on the British Paleocene Igneous Province (BPIP) has historically focused on the emplacement, chemistry and chronology of its elaborate central intrusive complexes and lava fields. However, the BPIP has also been dramatically shaped by numerous erosion, sedimentation and volcano-tectonic events, the significance of which becomes ever clearer as localities in the BPIP are re-investigated and our understanding of volcano-sedimentary processes advances. The resultant deposits provide important palaeo-environmental, palaeo-geographical and stratigraphical information, and highlight the wide range of processes and events that occur in ancient volcanic settings such as the BPIP. In this paper we review the sedimentary and volcano-tectonic processes that can be distinguished in the BPIP, and conceptualize them within a generalized framework model. We identify, and describe, the sedimentary responses to four broadly chronological stages in the history of the BPIP volcanoes: (1) the development of the lava fields, (2) early intrusion-induced uplift, (3) caldera collapse and (4) post-volcano denudation and exhumation of central complexes. We highlight and illustrate the range of sedimentary processes that were active in the BPIP. These operated on and helped shape a dynamic landscape of uplands and lowlands, of alluvial fans, braided rivers, lakes and swamps, and of volcanoes torn apart by catastrophic mass wasting events and/or caldera collapse.
The onset of the North Atlantic Igneous Province in a rifting perspective
Authors: HANSEN J. , JERRAM D. A. , McCAFFREY K. , PASSEY S. R.
Published: March 2009

The processes that led to the onset and evolution of the North Atlantic Igneous Province (NAIP) have been a theme of debate in the past decades. A popular theory has been that the impingement on the lower lithosphere of a hot mantle plume (the ‘Ancestral Iceland’ plume) initiated the first voluminous outbursts of lava and initiated rifting in the North Atlantic area in Early Palaeogene times. Here we review previous studies in order to set the NAIP magmatism in a time–space context. We suggest that global plate reorganizations and lithospheric extension across old orogenic fronts and/or suture zones, aided by other processes in the mantle (e.g. local or regional scale upwellings prior to and during the final Early Eocene rifting), played a role in the generation of the igneous products recorded in the NAIP for this period. These events gave rise to the extensive Paleocene and Eocene igneous rocks in W Greenland, NW Britain and at the conjugate E Greenland–NW European margins. Many of the relatively large magmatic centres of the NAIP were associated with transient and geographically confined doming in Early Paleocene times prior to the final break-up of the North Atlantic area.
Two non-trivial solutions for a non-homogeneous Neumann problem: an Orlicz–Sobolev space setting
Authors: Kristály Alexandru , Mihăilescu Mihai , Rădulescu Vicenţiu
Published: March 2009

In this paper we study a non-homogeneous Neumann-type problem which involves a nonlinearity satisfying a non-standard growth condition. By using a recent variational principle of Ricceri, we establish the existence of at least two non-trivial solutions in an appropriate Orlicz–Sobolev space.
Norm-attaining operators into Lorentz sequence spaces
Authors: Acosta María D.
Published: March 2009

We prove that the Lorentz sequence spaces do not have the property B of Lindenstrauss. In fact, for any admissible sequences w, v ∈ c0 \ l1, the set of norm-attaining operators from the Orlicz space hϕ(w) (ϕ is a certain Orlicz function) into d(v, 1) is not dense in the corresponding space of operators. We also characterize the spaces such that the subset of norm-attaining operators from the Marcinkiewicz sequence space into its dual is dense in the space of all bounded and linear operators between them.
Remarks on generalized elliptic integrals
Authors: Zhang Xiaohui , Wang Gendi , Chu Yuming
Published: March 2009

We study the monotonicity for certain combinations of generalized elliptic integrals, thus generalizing analogous well-known results for classical complete elliptic integrals, and prove a conjecture put forward by Heikkala, Vamanamurthy and Vuorinen.
Universal inequalities for eigenvalues of a system of elliptic equations
Authors: Cheng Qing-Ming , Yang Hong-Cang
Published: March 2009

Let D be a bounded domain in an n-dimensional Euclidean space ℝn. Assume that

are eigenvalues of an eigenvalue problem of a system of n elliptic equations:

In particular, when n=3, the eigenvalue problem describes the behaviour of the elastic vibration. We obtain universal inequalities for eigenvalues of the above eigenvalue problem by making use of a direct and explicit method; our results are sharper than one of Hook. Furthermore, a universal inequality for lower-order eigenvalues of the above eigenvalue problem is also derived.
On structure theory of pre-Hilbert algebras
Authors: Mira José Antonio Cuenca
Published: March 2009

Let A be a real (non-associative) algebra which is normed as real vector space, with a norm ‖·‖ deriving from an inner product and satisfying ‖ac‖ ≤ ‖a‖‖c‖ for any a,c ∈ A. We prove that if the algebraic identity (a((ac)a))a = (a2c)a2 holds in A, then the existence of an idempotent e such that ‖e‖ = 1 and ‖ea‖ = ‖a‖ = ‖ae‖, a ∈ A, implies that A is isometrically isomorphic to ℝ, ℂ, ℍ, $\mathbb{O}$,\, $\stackrel{\raisebox{4.5pt}[0pt][0pt]{\fontsize{4pt}{4pt}\selectfont$\star$}}{\smash{\CC}}$,\, $\stackrel{\raisebox{4.5pt}[0pt][0pt]{\fontsize{4pt}{4pt}\selectfont$\star$}}{\smash{\mathbb{H}}}$,\, $\stackrel{\raisebox{4.5pt}[0pt][0pt]{\fontsize{4pt}{4pt}\selectfont$\star$}}{\smash{\mathbb{O}}}$ or ℙ. This is a non-associative extension of a classical theorem by Ingelstam. Finally, we give some applications of our main result.
Inverse problems for invariant algebraic curves: explicit computations
Authors: Christopher Colin , Llibre Jaume , Pantazi Chara , Walcher Sebastian
Published: March 2009

Given an algebraic curve in the complex affine plane, we describe how to determine all planar polynomial vector fields which leave this curve invariant. If all (finite) singular points of the curve are non-degenerate, we give an explicit expression for these vector fields. In the general setting we provide an algorithmic approach, and as an alternative we discuss sigma processes.
Electrolyte and salt disturbances in older people: causes, management and implications
Authors: Soiza Roy L , Hoyle Graeme E , Chua Melvin PW
Published: March 2009

Salt and electrolyte disturbances are commonly encountered in older patients. A sound understanding of the underlying physiological and pathological mechanisms underpinning the predisposition of older people to the common electrolyte imbalances can help clinicians minimize their considerable associated morbidity and mortality. This review focuses on the more common and clinically relevant salt and electrolyte disorders of older people. The epidemiology, causes, symptoms, diagnosis and treatment of hyponatraemia, hypernatraemia, hyperkalaemia, hypokalaemia and calcium and phosphate imbalance in old age are covered from a clinician's perspective.
Olivine enigma: Why alteration controls the seismic properties of oceanic gabbros
Authors: Carlson R. L. , Miller D. Jay , Newman J.
Published: March 2009

The objective of this study was to determine whether the effects of low Mg content and/or cracks that typically populate olivine grains can explain why P and S wave velocities in samples of oceanic gabbro do not increase with increasing olivine content. The Mg content of olivine in these rocks is known to be appreciably less than Fo90, and optical, SEM, and electron microprobe analyses indicate that the “olivine” is actually an aggregate of olivine and 5–15% crack fill consisting of talc and/or serpentine plus magnetite. Voigt average models show that there is a strong, positive correlation between P wave velocities and Fo90 content but no correlation with Fo73. Because of its Mg content, olivine that is typical of oceanic gabbros does not influence seismic velocities. Adding 11% alteration of olivine to serpentine plus magnetite in the form of crack fill to the Fo73 model yields a nearly exact match between the model and measured P and S wave velocities. The fact that the crack fill consists largely of talc and/or serpentine indicates that these minerals formed by hydrothermal alteration in young, hot (>150°C) lower crust. Hence our results apply to gabbros in situ, as well as to the laboratory samples; seismic velocities in lower oceanic crust produced at high and intermediate spreading rates are controlled principally by the degree of hydrothermal alteration of the gabbros that compose the lower crust.
On the dynamical behaviour of low‐frequency earthquake swarms prior to a dome collapse of Soufrière Hill volcano, Montserrat
Authors: Hammer C. , Neuberg J. W.
Published: March 2009

A series of low‐frequency earthquake swarms prior to a dome collapse on Soufrière Hills volcano, Montserrat, are investigated with the emphasis on event rate and amplitude behaviour. In a single swarm, the amplitudes of consecutive events tend to increase with time, while the rate of event occurrence accelerates initially and then decelerates toward the end of the swarm. However, when consecutive swarms are considered, the average event rates seem to follow the material failure law, and the time of the dome collapse can be successfully estimated using the inverse event rate. These patterns in amplitude and event rate are interpreted as fluctuations in magma ascent velocity, which result in both the generation of low‐frequency events as well as cyclic ground deformation accompanying the swarm activity.
MODIS observations of enhanced clear sky reflectance near clouds
Authors: Várnai Tamás , Marshak Alexander
Published: March 2009

Several recent studies have found that the brightness of clear sky systematically increases near clouds. Understanding this increase is important both for a correct interpretation of observations and for improving our knowledge of aerosol‐cloud interactions. However, while the studies suggested several processes to explain the increase, the significance of each process is yet to be determined. This study examines one of the suggested processes—three‐dimensional (3‐D) radiative interactions between clouds and their surroundings—by analyzing a large dataset of MODIS (Moderate Resolution Imaging Spectroradiometer) observations over the Northeast Atlantic Ocean. The results indicate that 3‐D effects are responsible for a large portion of the observed increase, which extends to about 15 km away from clouds and is stronger (i) at shorter wavelengths (ii) near optically thicker clouds and (iii) near illuminated cloud sides. This implies that it is important to account for 3‐D radiative effects in the interpretation of solar reflectance measurements over clear regions in the vicinity of clouds.
Nonstationarity of a two‐dimensional perpendicular shock: Competing mechanisms
Authors: Lembège Bertrand , Savoini Philippe , Hellinger Petr , Trávníček Pavel M.
Published: March 2009

Two‐dimensional particle‐in‐cell (PIC) simulations are used for analyzing in detail different nonstationary behaviors of a perpendicular supercritical shock. A recent study by Hellinger et al. (2007) has shown that the front of a supercritical shock can be dominated by the emission of large‐amplitude whistler waves. These waves inhibit the self‐reformation driven by the reflected ions; then, the shock front appears almost “quasi‐stationary.” The present study stresses new complementary results. First, for a fixed βi value, the whistler waves emission (WWE) persists for high MA above a critical Mach number (i.e., MA ≥ MAWWE). The quasi‐stationarity is only apparent and disappears when considering the full 3‐D field profiles. Second, for lower MA, the self‐reformation is retrieved and becomes dominant as the amplitude of the whistler waves becomes negligible. Third, there exists a transition regime in MA within which both processes compete each other. Fourth, these results are observed for a strictly perpendicular shock only as B0 is within the simulation plane. When B0 is out of the simulation plane, no whistler waves emission is evidenced and only self‐reformation is recovered. Fifth, the occurrence and disappearance of the nonlinear whistler waves are well recovered in both 2‐D PIC and 2‐D hybrid simulations. The impacts on the results of the mass ratio (2‐D PIC simulations), of the resistivity and spatial resolution (2‐D hybrid simulations), and of the size of the simulation box along the shock front are analyzed in detail.
Storm time density enhancements in the middle‐latitude dayside ionosphere
Authors: Heelis R. A. , Sojka J. J , David M. , Schunk R. W.
Published: March 2009

Enhancements of the total electron content (TEC) in the middle‐latitude dayside ionosphere have often been observed during geomagnetic storms. The enhancements can be as large as a factor of 2 or more, and many sightings of such structures have occurred over the United States. Here we investigate the effectiveness of an expanded convection electric field as a mechanism for producing such ionospheric enhancements. As a test case, we examine the storm period of 5–7 November 2001, for which observations from the DMSP F13 are used to drive the Time Dependent Ionospheric Model (TDIM). Our findings indicate that at favorable universal times, the presence of the expanded electric field is sufficient to create dayside TEC enhancements of a factor of 2 or more. The modeled enhancements consist of locally produced plasma; we do not find it necessary to transport high‐density plasma northward from low latitudes.
Nonlinear electrostatic instabilities in the solar wind
Authors: Gomberoff L.
Published: March 2009

It is well known that nonlinear electrostatic instabilities can be triggered in a plasma with streaming ion species in the presence of finite‐amplitude Alfvén cyclotron waves. The instability occurs when the phase velocity of linear ion‐acoustic waves propagating forward and backward relative to the supporting ion species become equal owing to the presence of the finite‐amplitude wave. On the other hand, it has been shown recently that nonlinear ion‐acoustic‐like instabilities can also occur when the phase velocity of ion‐acoustic waves propagating forward relative to the supporting ion species become equal to the phase velocity of ion‐acoustic waves propagating backward relative to another supporting ion species. This can occur in a system with one streaming ion species relative to the background plasma and, in a completely different regime, when there is more than one drifting ion species. These instabilities may play a role in the evolution of the fast solar wind.
Airwaves generated by an underwater explosion: Implications for volcanic infrasound
Authors: Ichihara M. , Ripepe M. , Goto A. , Oshima H. , Aoyama H. , Iguchi M. , Tanaka K. , Taniguchi H.
Published: March 2009

A shallow explosion in a fluid is one of the fundamental processes of airwave generation in volcanic eruptions. To better understand the mechanism of the airwave generation, underwater explosion experiments were conducted. Although the underwater explosions have been intensely studied over the last century, airwaves have received little attention. In this study, pressure waves were measured in air and under water, and the corresponding motion of the water surface was captured by a high‐speed video camera. Airwaves and associated styles of the surface motion show similarities determined by the scaled depth, defined as the depth divided by the cubic root of the explosion energy. The air waveforms are quite different from the pressure waves measured in the water and cannot be completely explained by linear transmission of pressure waves from water to air. The mechanism of airwave generation is a combination of wave transmission and dynamics of the interface boundary. The first mechanism directly reflects the explosion source, and the same source is also observed as the underwater pressure waves. On the other hand, the second is not necessarily visible in the underwater pressure waves but will provide information on the mechanical properties and behavior of the material above the explosion source. Each mechanism is analyzed in the experiments.
Bed slope effects on turbulent wave boundary layers: 2. Comparison with skewness, asymmetry, and other effects
Authors: Fuhrman D. R. , Fredsøe J. , Sumer B. M.
Published: March 2009

A numerical model solving incompressible Reynolds‐averaged Navier‐Stokes equations, combined with a two‐equation k‐ω model for turbulence closure, is used to systematically compare the relative strength of bed shear stress quantities and boundary layer streaming under wave motions from four contributions believed to play a prominent role in cross‐shore boundary layer and sediment transport processes: (1) converging‐diverging effects from bed slope, (2) wave skewness, (3) wave asymmetry, and (4) waves combined with superposed negative currents (intended to loosely represent, for example, return currents or undertow). The effects from each of the four components are isolated and quantified using a standard set of bed shear stress quantities, allowing their easy comparison. For conditions representing large shallow‐water waves on steep slopes, the results suggest that converging‐diverging effects from beach slope may make a significant onshore bed load contribution. Generally, however, the results suggest wave skewness (in addition to conventional steady streaming) as the most important onshore contribution outside the surf zone. Streaming induced within the wave boundary layer is also investigated for each component, and skewness and asymmetry are demonstrated to promote largely negative streaming velocities, consistent with earlier work. For hydraulically smooth cases, however, a thin region of positive streaming is revealed in the viscous sublayer which is effectively absent in hydraulically rough conditions. Cross‐shore boundary layer dynamics are generally acknowledged to be a complicated combination of numerous competing physical processes, and this work is among few to systematically compare a number of these. It is hoped that the results will be useful in assessing which of the contributions considered will be most prominent for a given set of local wave and beach slope conditions.
Interferometric direction finding of over‐horizon VHF transmitter signals and natural VHF radio emissions possibly associated with earthquakes
Authors: Yasuda Y. , Ida Y. , Goto T. , Hayakawa M.
Published: March 2009

The over‐horizon (out‐of‐sight) VHF transmitter signals are found to be received before an earthquake, and also natural VHF noises are known to be detected prior to an earthquake. In order to have a better understanding of these over‐horizon VHF signals and noises, an interferometric direction‐finding system has been, for the first time, introduced, and some preliminary observational results have been presented here. With FM Sendai as a target VHF transmitter (at 77.1 MHz), we have carried out the observation at Chofu (Tokyo). We can receive occasionally the over‐horizon VHF transmission signals in possible association with earthquakes. We have analyzed a few earthquakes since the commencement of our observation, including a large one named the Niigata Chuetsu‐oki earthquake. The azimuth distribution by means of the interferometer has enabled us to correlate any burst in the temporal evolution of electric field intensity to a certain earthquake. The over‐horizon VHF transmitter signals are always well above the background noise, whose azimuth is found to be relatively close to the direction of Sendai (relatively away from the epicentral direction). Then, the VHF radio noises are always simultaneously detected as an enhancement of background noise, with their azimuths being relatively close to the epicenter of the quake. The mechanisms of seismoatmospheric perturbations as seen from the over‐horizon VHF signal, as well as the natural VHF noise, are discussed.