bluuebunny/crossref_metadata_2025 huggingface dataset:
Spin crossover in Fe(II) complexes: An ab initio study of ligand σ‐donation
Authors: Domingo Alex , Àngels Carvajal Maria , de Graaf Coen
Published: May 2009

The relative stability of high‐spin and low‐spin states has been studied in a series of Fe(II) complexes with model ligands of different σ donation strength. The natural (delocalized) orbitals are transformed to atomic‐like orbitals to analyze the multiconfigurational wave function in a valence bond picture. This analysis reveals a direct relation between the stabilization of the low‐spin state and the importance of the ligand‐to‐metal charge transfer in the σ orbitals. The multiconfigurational second‐order perturbation theory (CASPT2) energy dependence of the low‐spin state as function of the Fe‐ligand distance deviates significantly from coupled cluster (CCSD(T)) calculations. This is ascribed to the intrinsic multiconfigurational character of the wave function of the low‐spin state, invalidating the use of the simple closed‐shell reference in the coupled cluster calculations. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Cusps and derivatives for wave‐functions expanded in Slater orbitals: A density study
Authors: Reinhardt Peter , Hoggan Philip E.
Published: May 2009

This article recalls basic properties of Slater type Orbital (STO) basis sets, in particular, with respect to satisfying Kato's electron‐nucleus cusp condition. It is shown that a suitable starting point is the set of hydrogen‐like orbitals or, more flexibly, their generalization as Coulomb Sturmians. A case study is presented on the Hartree–Fock density obtained for a water molecule, N2, and CO2 showing that the nuclear cusp condition may be easily accounted for near the heavier nuclei, but only with difficulties at the hydrogen center. In particular, bond stretching affects the expected cusp condition on hydrogen atoms. Some indications are given on the improvement of STO basis sets. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Microscopic branching processes: The O + O2 reaction and its relaxed potential representations
Authors: Rampino Sergio , Skouteris Dimitris , Laganà Antonio
Published: May 2009

An analysis of the O3 DMBE potential energy surface is performed using unconventional contour maps. In this way alternative paths leading to the same products (microscopic branching) are singled out. The detailed J = 0 quantum probabilities and related mode selectivity and energy disposal obtained through an extensive computational campaign on the EGEE production Grid are interpreted in terms of the mentioned alternative reactive paths. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Molecular recognition in cation‐exchanged zeolites
Authors: Pidko Evgeny A. , van Santen Rutger A.
Published: May 2009

The concepts of confinement‐ and molecular recognition‐driven chemical reactivity of cation‐exchanged zeolites is illustrated by our recent results from periodic and cluster density functional theory (DFT) calculations. The reactivity of alkali‐earth‐ and alkaline‐exchanged low‐silica zeolites for selective photo‐oxidation of alkenes with molecular oxygen and for N2O4disproportionation is shown to be mainly due to the specific arrangement and the size of the cations in the zeolite cage. An attempt is made to separate the effects of basicity of the framework, the Lewis acidity of the extra‐framework cations and the electrostatic field in the zeolite cage as well as its geometrical properties for the respective reactions. The importance of the favorable adsorption fashion of the reagents controlled by noncovalent interactions with the microporous matrix is shown. The role of the weak interactions with the zeolite walls and the factors, which determine the preference for a particular adsorption mode, are discussed by the example of light alkanes adsorption to Mg‐ and Ca‐exchanged faujasites. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Phase behavior of ionic clusters down to nanoscale. A review of recent work
Authors: Rodrigues Pedro C. R. , Silva Fernandes Fernando M. S.
Published: May 2009

As finding an exact and manageable partition function for nanoclusters is a desirable but, so far, unattainable task, approximated treatments are proposed to explain and predict phase changes and phase coexistence at these size scales. In this article, a review of those approaches is presented, mainly focusing the authors work on the subject. The foundations and limitations of the proposed models are discussed and perspectives for extended treatments are given. The discussions are illustrated with new molecular dynamics simulations of unconstrained NaI and NaCl clusters. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Davydov's solitons in a homogeneous nucleotide chain
Authors: Lakhno Victor D.
Published: May 2009

Charge transfer in homogeneous nucleotide chains is modeled on the basis of Holstein Hamiltonian. The path length of Davydov solitons in these chains is being studied. It is shown that in a dispersionless case, when the soliton velocity V is small, the path length grows exponentially as V decreases. In this case, the state of a moving soliton is quasisteady. In the presence of dispersion determined by the dependence Ω2 = Ω + Vκ2, the path length in the region 0 < V < V0 is equal to infinity. In this case, the phonon environment follows the charge motion. In the region V > V0, the soliton motion is accompanied by emission of phonons which leads to a finite path length of a soliton. The latter tends to infinity as V → V0 + 0 and V → ∞. The presence of dissipation leads to a finite soliton path length. An equilibrium velocity of soliton in an external electric field is calculated. It is shown that there is a maximum intensity of an electric field at which a steady motion of a soliton is possible. The soliton mobility is calculated for the stable or ohmic brunch. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
The effect of drug‐DNA interactions on the intercalation site formation
Authors: Miroshnychenko K. V. , Shestopalova A. V.
Published: May 2009

The problem of intercalation site formation in the undistorted B‐DNA of different length and sequence was considered. Three models of DNA intercalation targets were proposed that accounted for the binding features of intercalators ethidium, daunomycin and 9‐amino[N‐(2‐dimethylamino)ethyl]‐acridine‐4‐carboxamide (9‐amino‐DACA). The automated docking of ligands into the constructed DNA‐targets produced correct structures of complexes for ethidium and daunomycin when asymmetrically unwound DNA was used as target. To obtain the correct structure of 9‐amino‐DACA‐DNA complex, the manual docking was applied. The results of docking of ligands into different DNA‐targets indicate that, upon formation of the intercalation target, it is sufficient to take into account only the most significant unwinding in one particular helical step: in the intercalation step (for ethidium and 9‐amino‐DACA) or in the adjacent helical step (for daunomycin). The unwinding or overwinding of subsequent helical steps could be refined later during the optimization of the obtained intercalation complex. The unwinding of the DNA helical step on the large angle produces the 5′‐North/3′‐South asymmetry of sugar conformations in this step. The value of the total unwinding of the DNA in the intercalation complex was found to be dependent on the sequence and length of the DNA‐target. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Biocompatible Near‐Infrared Quantum Dots as Ultrasensitive Probes for Long‐Term in vivo Imaging Applications
Authors: Yong Ken‐Tye , Roy Indrajit , Ding Hong , Bergey Earl J. , Prasad Paras N.
Published: May 2009

A facile synthesis method to produce monodisperse, biocompatible, lysine crosslinked mercaptoundecanoic acid (MUA) CdSe0.25Te0.75/CdS near‐infrared (NIR) quantum dots and use them as probes to study their long term in vivo distribution, clearance, and toxicity is presented. Large signal enhancements are demonstrated by these quantum dots, which enables their use as efficient and sensitive probes for live‐animal imaging. An important finding is that mice intravenously injected with ≈10.5 mg kg−1 of NIR QDs survive for more than three months without any apparent adverse effect to their health. Furthermore, it is determined that there is a significant reduction in the number of the QDs in the liver and spleen three months post injection. In addition, histological analysis of heart, kidney, liver, spleen, and lung tissue indicates that there are no acute toxic effects from these lysine cross‐linked MUA NIR QDs. This study suggests that these NIR QDs can be potentially used for long‐term targeted imaging and therapy studies in vivo.
Testing facility for experimental evaluation of non‐structural components under full‐scale floor motions
Authors: Mosqueda Gilberto , Retamales Rodrigo , Filiatrault Andre , Reinhorn Andrei
Published: May 2009

The seismic vulnerability of non‐structural components and equipment with their expensive recovery and/or replacement costs has been demonstrated during past earthquakes. With the exception of the nuclear industry, the limited data collected from past earthquakes are not sufficient to completely characterize the seismic behaviour of non‐structural components and to develop effective mitigation measures. To address these limitations, the University at Buffalo has commissioned a dedicated non‐structural component simulator (University at Buffalo non‐structural component simulator (UB‐NCS)) composed of a two‐level testing frame capable of simultaneously subjecting both displacement and acceleration‐sensitive non‐structural components to realistic full‐scale floor motions expected within multi‐storey buildings. Current codes now require seismic qualification of important non‐structural components, and protocols for experimental qualification have been developed considering existing laboratory limitations. The new testing capabilities provided by the UB‐NCS are described to demonstrate the improved and more realistic qualification procedures that can be achieved. Results are presented from a test on two parallel partition walls aimed to verify the capabilities of the UB‐NCS. Copyright © 2008 John Wiley & Sons, Ltd.
An evaluation of energy response and cumulative plastic rotation demand in steel moment‐resisting frames through dynamic/static pushover analyses
Authors: Akbas Bülent , Tugsal Ülgen Mert , Kara F. İlknur
Published: May 2009

In the energy‐based design approach, the seismic design is performed through the balancing of the energy input and the energy dissipation of the structure. The energy dissipation is represented by the hysteretic energy dissipation capacity defined as the total area enclosed in the force–deformation curves under cyclic loading. Thus, the energy‐based design approach considers the cumulative effect of the seismic loading of the structure. The cumulative damage in the structural members can be expressed in terms of cumulative plastic rotation (CPR). The CPR capacity plays an important role in determining the hysteretic energy dissipation capacity of a steel moment connection. This study investigated the energy response and the CPR capacity and demand through dynamic pushover analyses on steel moment‐resisting frames. The results were compared with the ones obtained from the pushover analysis. Copyright © 2008 John Wiley & Sons, Ltd.
One‐dimensional finite element solution for non‐uniform tall building structures and loading
Authors: Savassi Walter , Mancini Eddie
Published: May 2009

By using a one‐dimensional finite element numerical version based on the continuous medium technique, plane panels of variable geometry and loading are considered, in order to emphasize the capacity of a corresponding very simple computer code. Twin shear walls linked by lintel beams, with walls of lower storeys having bigger cross‐section than the next upper floors, are considered under variable horizontal wind loading through the building height. Afterwards, in that same panel, stronger discrete lintel beam is subsequently placed at each floor position. Results may show where is the optimum level to place those reinforcements in order to get, for example, the smaller top horizontal deflection. The second example considers the case of shear wall curtailment, in the frame shear wall association by pinned bars. Due to the individual behaviour of a single shear wall and of a single frame, it is possible (and real construction may permit that) to construct the wall up to a certain level, smaller than the building height, without having any significant change in the panel top displacement. By using the particular continuous medium finite element computer code, developed by the first author, it is possible to analyse several modelled structures, each having the curtailed wall at subsequent levels, from base to top, and to build an ‘influence line’ to find out the optimum curtailment level. Comparisons with the matrix discrete method and with analytical solutions were considered. Reference to free vibration solutions for such structures was also made. Copyright © 2008 John Wiley & Sons, Ltd.
Fluorine‐containing nanoemulsions for MRI cell tracking
Authors: Janjic Jelena M. , Ahrens Eric T.
Published: May 2009

In this article we review the chemistry and nanoemulsion formulation of perfluorocarbons used for in vivo 19F MRI cell tracking. In this application, cells of interest are labeled in culture using a perfluorocarbon nanoemulsion. Labeled cells are introduced into a subject and tracked using 19F MRI or NMR spectroscopy. In the same imaging session, a high‐resolution, conventional (1H) image can be used to place the 19F‐labeled cells into anatomical context. Perfluorocarbon‐based 19F cell tracking is a useful technology because of the high specificity for labeled cells, ability to quantify cell accumulations, and biocompatibility. This technology can be widely applied to studies of inflammation, cellular regenerative medicine, and immunotherapy. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Diagnostic Tools > In Vivo Nanodiagnostics and Imaging
Nanofibrous composites for tissue engineering applications
Authors: McCullen Seth D. , Ramaswamy Sangeetha , Clarke Laura I. , Gorga Russell E.
Published: May 2009

Development of artificial matrices for tissue engineering is a crucial area of research in the field of regenerative medicine. Successful tissue scaffolds, in analogy with the natural mammalian extracellular matrix (ECM), are multi‐component, fibrous, and on the nanoscale. In addition, to this key morphology, artificial scaffolds must have mechanical, chemical, surface, and electrical properties that match the ECM or basement membrane of the specific tissue desired. In particular, these material properties may vary significantly for the four primary tissues in the body: nerve, muscle, epithelial, and connective. In order to address this complex array of attributes with a polymeric material, a nanocomposite approach, employing a blend of materials, addition of a particle to enhance particular properties, or a surface treatment, is likely to be required. In this review, we examine nanocomposite approaches to address these diverse needs as a function of tissue type. The review is intended as a bridge between material scientists and biomedical researchers to give basic background information on tissue biology to the former, and on material processing approaches to the latter, in a general manner, and specifically review fibrous nanocomposite materials that have previously been used for cell studies, either in vivo or in vitro. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement
Characterization of Cross‐Linked Lipase Aggregates
Authors: Prabhavathi Devi B. L. A. , Guo Zheng , Xu Xuebing
Published: May 2009

Commercially available microbial lipases from different sources were immobilized as cross‐linked enzyme aggregates (CLEAs) using different precipitants and glutaraldehyde as cross‐linkers. These CLEAs were assayed based on esterification between lauric acid and n‐propanol in solvent‐free systems. Precipitants were found to have a profound influence on both specific activities and total activity recovery of CLEAs, as exemplified by Candida antarctica lipase B (CALB). Among the CLEAs of CALB studied, those obtained using PEG600, ammonium sulfate, PEG200 and acetone as precipitants were observed to attain over 200% total activity recovery in comparison with acetone powder directly precipitated from the liquid solution by acetone. PEG200 precipitated CLEA gave the best specific activity (139% relative to acetone powder). The results of kinetic studies showed that Vmax/Km does not significantly change upon CLEA formation. This work presents a characterization of CLEAs based on an esterification activity assay, which is useful for exploring the synthetic application potential of CLEA technology with favorable perspectives.
Solving the Economic Crisis: The Role of the EU
Authors: Daul Joseph
Published: May 2009

The author argues that over the past few months, the political centre-right has become the most credible option in regards to future economic reforms. The proposed framework which balances competitiveness with rules to protect European citizens, while at the same time maintaining the core values of freedom and responsibility, is the best recipe for an effective economic recovery. The author underlines the importance of facing this first global economic crisis by adapting our values to the new era, suggesting that although faced by difficult times, the world has been offered powerful incentives to change. He argues that the single market is part of the solution and not the problem in this financial crisis. Only by working together, yet respecting the rules of subsidiarity at all times and avoiding protectionism at all costs, will the EU both overcome the recession and ensure that a similar situation will never happen again.
Relationship between thallus size and apothecium density in two alpine umbilicate lichens
Authors: SHIMIZU Akira , KUBO Takuya
Published: May 2009

The relationship between thallus size and apothecium density was studied in two umbilicate lichens,Umbilicaria cylindricaandLasallia pensylvanica, growing in alpine rock surface environments. Samples of the two lichens were collected from the Daisetsuzan National Park, northern Japan.Umbilicaria cylindricaproduced many smaller apothecia, whereasL. pensylvanicahad larger but fewer apothecia. To explain the differences in reproductive efforts between these two species, we analyzed the lichen data using a hierarchical Bayesian model in which the density of apothecia for each species was predicted by the thallus area and the sky openness index (SOI). The Bayesian model including unobservable effects, i.e. the random effects of individual lichens and rock faces, predicted that the apothecium density for both species increased as the thallus area increased. The estimated coefficient of thallus area to apothecium density forU. cylindricawas larger than that forL. pensylvanica. We also detected a probable positive relationship between SOI and apothecium density forU. cylindrica, whereas none was detected forL. pensylvanica.
Molecular data show thatBryoria fremontiiandB. tortuosa(Parmeliaceae) are conspecific
Authors: VELMALA Saara , MYLLYS Leena , HALONEN Pekka , GOWARD Trevor , AHTI Teuvo
Published: May 2009

Bryoria fremontiiandB. tortuosaare the only species in the lichenized ascomycete genusBryoriaknown to contain the pulvinic acid derivative vulpinic acid. InB. fremontiithis yellow pigment is restricted to the soralia and apothecia, while inB. tortuosait can occur throughout the thallus. The actual amount of vulpinic acid produced byB. tortuosais rather variable, however, with intermediate specimens bearing both white and yellow pseudocyphellae. We studied the relationship between the two species with parsimony analysis using four DNA regions: 1) the internal transcribed spacers of the nuclear rDNA including the 5.8S region (ITS), 2) partial sequences from the intergenic spacer of the nuclear rDNA (IGS), 3) partial sequences from the small subunit of the mitochondrial rDNA (mtSSU), and 4) partial sequences from the protein-coding glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH). Our phylogenetic analysis revealed thatB. fremontiiandB. tortuosamust be regarded as conspecific, but allowing for some genetic differentiation between European and North American populations.Bryoria tortuosais therefore synonymized withB. fremontii.
A new, Asian species in the Parmeliella mariana complex (Pannariaceae)
Authors: JØRGENSEN Per M.
Published: May 2009

Parmeliella zeylanica is described as a new species in the P. mariana group, although it differs from all known species in the group by not having radiating marginal lobes resting on a distinct mat of rhizohyphae. It is as yet known only from the highlands of Sri Lanka. The new combination Parmeliella leiostroma (Nyl.) P. M. Jørg. is made for a closely related species from the same region, and it is shown that Parmeliella endomilta var. achromatica Makhija & Adawara falls within the variation of Parmeliella mariana (Fr.) P. M.Jørg. & D. J. Galloway, and is not closely related to P. endomilta.
A new species ofMelanotopelia(Graphidaceae) from Africa
Authors: SÉRUSIAUX Emmanuël , BRAND A. Maarten , FISCHER Eberhard , KILLMANN Dorothee , van den BOOM Pieter P. G. , ERTZ Damien
Published: May 2009

Melanotopelia africanais described as new to science from Rwanda (continental Africa) and La Réunion (Mascarenes archipelago).Topeliopsis muscigenais here reported for the first time from La Réunion.
Robot navigation: implications from search strategies in exploring crayfish
Authors: Heußlein Edith , Patullo Blair W. , Macmillan David L.
Published: May 2009

Biomimetic applications play an important role in informing the field of robotics. One aspect is navigation – a skill automobile robots require to perform useful tasks. A sub-area of this is search strategies, e.g. for search and rescue, demining, exploring surfaces of other planets or as a default strategy when other navigation mechanisms fail. Despite that, only a few approaches have been made to transfer biological knowledge of search mechanisms on surfaces along the ground into biomimetic applications. To provide insight for robot navigation strategies, this study describes the paths a crayfish used to explore terrain. We tracked movement when different sets of sensory input were available. We then tested this algorithm with a computer model crayfish and concluded that the movement of C. destructor has a specialised walking strategy that could provide a suitable baseline algorithm for autonomous mobile robots during navigation.
Writing in Cameroon pidgin English: begging the question
Authors: Sala Bonaventure M.
Published: May 2009

Cameroon Pidgin English (CPE) is increasingly becoming an important language in the country, judging from its use in the media (both private and public), in literary texts, the Bible and other religious materials. The soaring of writing in CPE has been hailed by many as a positive signal for the spread and survival of the language, but this begs the question of how it should be written. Formal statements made so far on how CPE should be written are divergent (see Todd, 1986; Mbangwana, 1983; Ayafor, 1996 and Schr¨der, 2003) and in practice the present situation of CPE writing is marred by inconsistency, where the English- and the phonetically-based options compete (see Schneider, 1960 and Awah, 1981). For a full-blown literature (which standardises a language in many respects) to flourish, there is need for an agreed writing system that can make its literature better accessible to the public. We need to know what makes the one option superior to the other and why. Showcasing the literature in CPE as guarantee of viability, as Ayafor (2005) does, is not helpful if we do not pause to ask ourselves how it is, and should be, written. The purpose of this paper is to assess the controversies involved in talking about and conceiving a writing system for CPE. It is also to propose a writing system for CPE, based on linguistic and extra-linguistic parameters.
Maltese English and the nativization phase of the dynamic model
Authors: Thusat Joshua , Anderson Emily , Davis Shante , Ferris Mike , Javed Amber , Laughlin Angela , McFarland Christopher , Sangsiri Raknakwan , Sinclair Judith , Vastalo Victoria , Whelan Win , Wrubel Jessica
Published: May 2009

Research on new varieties of English often reflects specific lexical shifts between a standard variety of English and an outer or expanding variety of English. Studies conducted on Nigerian English, Indian English, Malaysian English, etc., list examples of morphological, syntactical, and lexical nativization without mentioning the evolutionary progression of a post colonial English (PCE). Edgar Schneider (2007) posits a Dynamic Model for plotting the timeline of any post colonial variety of English (PCE). The model reveals five fundamental evolutionary phases to any new English: foundation, exonormative stabilization, nativization, endonormative stabilization, and differentiation. At each phase, the structure of the settler strand (STL) and the indigenous strand (IDG) of English is affected at four different linguistic levels: history/politics, identity construction, sociolinguistics, and linguistic developments. In each phase, researchers of a PCE must find specific instances of development that correspond to the correct phase of evolution. In an attempt to assess the universal applicability of Schneider's (2007) Dynamic Model, this study seeks to use the country of Malta as an example of a new post colonial English residing primarily in phase three: nativization.
In pursuit of linguistic gold: mothering in a globalised world
Authors: Chew Phyllis Ghim-Lian
Published: May 2009

A follow-up of Jin-Kyu Park's contribution in ET97 on ‘English Fever’ in South Korea, by examining one of the consequences in Singapore – the destination for thousands of ‘study mothers’ who migrate from South Korea and China to help their young children acquire ‘linguistic capital’ by learning English.

This paper focuses on the existence of around 7000 Chinese (PRC) and 5000 Korean study mothers in 2007 in the Republic of Singapore (Toh, 2008). Known in their respective home countries as ‘wild goose mothers’ (kirogi omma) and ‘study mothers’ (pei du mama), these mothers leave their husbands behind while they accompany their children, some as young as 7 years, to a foreign country in the pursuit of linguistic gold. ‘We have good science and maths at home but we need the English to make it work.’
English as a lingua franca in aviation
Authors: Seiler Walter
Published: May 2009

The International Civil Aviation Organization now requires all airline pilots to have at least a basic command of conversational English, but Walter Seiler is concerned that an over-emphasis on native-speaker varieties might lead to even more misunderstandings.
BARTLETT CORRECTION IN THE STABLE AR(1) MODEL WITH INTERCEPT AND TREND
Authors: van Giersbergen Noud P.A.
Published: May 2009

Bartlett corrections are derived for testing hypotheses about the autoregressive parameter ρ in the stable (a) AR(1) model, (b) AR(1) model with intercept, (c) AR(1) model with intercept and linear trend. The correction is found explicitly as a function of ρ. In the models with deterministic terms, the correction factor is asymmetric in ρ. Furthermore, the Bartlett correction is monotonically increasing in ρ and tends to infinity when ρ approaches the stability boundary of + 1. Simulation results indicate that the Bartlett corrections are useful in controlling the size of the likelihood ratio statistic in small samples, although these corrections are not the ultimate panacea.
The triangle inequalities and lower semi-continuity of surface energy of partitions
Authors: Caraballo David G.
Published: May 2009

We prove that the triangle inequalities in general are not equivalent to lower semi-continuity of surface energy. In 1990, Ambrosio and Braides proved that the two conditions are equivalent when the number of regions, s, is three. They gave an example in the plane showing that the triangle inequalities do not imply lower semi-continuity when s ≥ 6. The cases when s = 4 and s = 5 have remained open. In this paper, we resolve these open questions and show that, in ℝm, the triangle inequalities are sufficient for lower semi-continuity if and only if s = 3.
On duality and spectral properties of (a, k)-regularized resolvents
Authors: Lizama Carlos , Prado Humberto
Published: May 2009

We construct a duality theory for (a, k)-regularized resolvents, extending some of the known theorems for dual semigroups. We present several classes of spaces, which in the semigroup case correspond to the Favard class and the sun-dual space. By duality arguments spectral inclusion theorems for regularized resolvents are also obtained.
On two-dimensional ferromagnetism
Authors: Pedregal Pablo , Yan Baisheng
Published: May 2009

We present a new method for solving the minimization problem in ferromagnetism. Our method is based on replacing the non-local non-convex total energy of magnetization by a new local non-convex energy of divergence-free fields. Such a general method works in all dimensions. However, for the two-dimensional case, since the divergence-free fields are equivalent to the rotated gradients, this new energy can be written as an integral functional of gradients and hence the minimization problem can be solved by some recent non-convex minimization procedures in the calculus of variations. We focus on the two-dimensional case in this paper and leave the three-dimensional situation to future work. Special emphasis is placed on the analysis of the existence/non-existence depending on the applied field and the physical domain.
Spectral properties of singular Sturm—Liouville operators with indefinite weight sgn x
Authors: Karabash Illya , Trunk Carsten
Published: May 2009

We consider a singular Sturm—Liouville expression with the indefinite weight sgn x. There is a self-adjoint operator in some Krein space associated naturally with this expression. We characterize the local definitizability of this operator in a neighbourhood of ∞. Moreover, in this situation, the point ∞ is a regular critical point. We construct an operator A = (sgn x)(−d2/dx2 + q) with non-real spectrum accumulating to a real point. The results obtained are applied to several classes of Sturm—Liouville operators.
Convex-transitive characterizations of Hilbert spaces
Authors: Talponen Jarno
Published: May 2009

We investigate real convex-transitive Banach spaces X, which admit a one-dimensional bicontractive projection P on X. Various mild conditions regarding the weak topology and the geometry of the norm are provided, which guarantee that such an X is in fact isometrically a Hilbert space. For example, if uESX is a big point such that there is a bicontractive linear projection P : X → [u] and X* is weak*-locally uniformly rotund, then X is a Hilbert space. The results obtained here are motivated by the well-known Banach—Mazur rotation problem, as well as a question posed by B. Randrianantoanina in 2002 about convex-transitive spaces.
Partial regularity of strong local minimizers of quasiconvex integrals with (p, q)-growth
Authors: Schemm Sabine , Schmidt Thomas
Published: May 2009

We consider strictly quasiconvex integrals

in the multi-dimensional calculus of variations. For the C2-integrand f : ℝNn → ℝ we impose (p, q)-growth conditions

with γ, Γ > 0 and 1 < p ≤ q < min {p + 1/n, p(2n − 1)/(2n − 2)}. Under these assumptions we prove partial C1, αloc-regularity for strong local minimizers of F and the associated relaxed functional F.
Purely Functional 1-2 Brother Trees
Authors: HINZE RALF
Published: May 2009

Enter the computing arboretum and you will find a variety of well-studied trees: AVL trees (Adel'son-Vel'skiĭ & Landis 1962), symmetric binary B-trees (Bayer 1972), Hopcroft's 2-3 trees (Aho et al. 1974), the bushy finger trees (Guibas et al. 1977) and the colourful red-black trees (Guibas & Sedgewick 1978). In this pearl, we look at a more exotic species of balanced search trees, 1-2 brother trees (Ottmann et al. 1979), which deserves to be better known. Brother trees lend themselves well to a functional implementation with deletion (Section 5) as straightforward as insertion (Section 3), both running in logarithmic time. Furthermore, brother trees can be constructed from ordered lists in linear time (Section 4). With some simple optimisations in place, this implementation of search trees is one of the fastest around. So, fasten your seat belts.
Adhesion ofPlasmodium falciparum-infected erythrocytes to human cells: molecular mechanisms and therapeutic implications
Authors: Rowe J. Alexandra , Claessens Antoine , Corrigan Ruth A. , Arman Mònica
Published: May 2009

Severe malaria has a high mortality rate (15–20%) despite treatment with effective antimalarial drugs. Adjunctive therapies for severe malaria that target the underlying disease process are therefore urgently required. Adhesion of erythrocytes infected withPlasmodium falciparumto human cells has a key role in the pathogenesis of life-threatening malaria and could be targeted with antiadhesion therapy. Parasite adhesion interactions include binding to endothelial cells (cytoadherence), rosetting with uninfected erythrocytes and platelet-mediated clumping of infected erythrocytes. Recent research has started to define the molecular mechanisms of parasite adhesion, and antiadhesion therapies are being explored. However, many fundamental questions regarding the role of parasite adhesion in severe malaria remain unanswered. There is strong evidence that rosetting contributes to severe malaria in sub-Saharan Africa; however, the identity of other parasite adhesion phenotypes that are implicated in disease pathogenesis remains unclear. In addition, the possibility of geographic variation in adhesion phenotypes causing severe malaria, linked to differences in malaria transmission levels and host immunity, has been neglected. Further research is needed to realise the untapped potential of antiadhesion adjunctive therapies, which could revolutionise the treatment of severe malaria and reduce the high mortality rate of the disease.
Determination of interplanetary coronal mass ejection geometry and orientation from ground‐based observations of galactic cosmic rays
Authors: Kuwabara T. , Bieber J. W. , Evenson P. , Munakata K. , Yasue S. , Kato C. , Fushishita A. , Tokumaru M. , Duldig M. L. , Humble J. E. , Silva M. R. , Dal Lago A. , Schuch N. J.
Published: May 2009

We have developed a method for determining interplanetary coronal mass ejection (ICME) geometry from galactic cosmic ray data recorded by the ground‐based muon detector network. The cosmic ray density depression inside the ICME, which is associated with a Forbush decrease, is represented by an expanding cylinder that is based on a theoretical model of the cosmic ray particle diffusion. ICME geometry and orientation are deduced from observed time variations of cosmic ray density and density gradient and are compared with those deduced from a magnetic flux rope model. From March 2001 to May 2005, 11 ICME events that produced Forbush decreases >2% were observed, and clear variations of the density gradient due to ICME passage were observed in 8 of 11 events. In five of the eight events, signatures of magnetic flux rope structure (large, smooth rotation of magnetic field) were also seen, and the ICME geometry and orientation deduced from the two methods were very similar in three events. This suggests that the cosmic ray‐based method can be used as a complementary method for deducing ICME geometry especially for events where a large Forbush decrease is observed.
Information‐centered representation of retrievals with limited degrees of freedom for signal: Application to methane from the Tropospheric Emission Spectrometer
Authors: Payne Vivienne H. , Clough Shepard A. , Shephard Mark W. , Nassar Ray , Logan Jennifer A.
Published: May 2009

Remote measurements of trace gas profiles from nadir‐viewing instruments are often retrieved and/or reported on a fine grid containing more levels than the number of independent pieces of information in the measurement. Such profiles contain a priori information, which complicates interpretation. For scientific analyses of these data it is desirable to move to a representation in which measurement information is dominant and the influence of a priori information is minimal. Presented here is a postprocessing approach using a simple algorithm to transform each retrieved profile to an appropriate, geographically varying coarse grid. The representation is chosen such that the averaging kernel is close to unity for regions of the atmosphere where the retrieval has most information. The approach takes advantage of the sensitivity characterization allowed by retrieval on a fine grid, while reducing the influence of the a priori, accounting for spatial and temporal variations in the sensitivity of the measurement to the true atmosphere, and preserving obvious physical meaning in the end product. The example used to demonstrate the approach is the methane product from the Tropospheric Emission Spectrometer (TES), which contains 0.5–2.0 degrees of freedom for signal, depending on season and location. The TES methane has been postprocessed, and the end product has been compared with results from GEOS‐Chem, a global chemical model. Results show realistic latitudinal gradients from the TES data. Model/measurement differences also show large‐scale features over Indonesia that we attribute to tropical biomass burning in the summer/fall.
Climate impacts of geoengineering marine stratocumulus clouds
Authors: Jones Andy , Haywood Jim , Boucher Olivier
Published: May 2009

Theoretical potential geoengineering solutions to the global warming problem have recently been proposed. Here, we present an idealized study of the climate response to deliberately seeding large‐scale stratocumulus cloud decks in the North Pacific, South Pacific, and South Atlantic, thereby inducing cooling via aerosol indirect effects. Atmosphere‐only, atmosphere/mixed‐layer ocean, and fully coupled atmosphere/ocean versions of the Met Office Hadley Centre model are used to investigate the radiative forcing, climate efficacy, and regional response of temperature, precipitation, and net primary productivity to such geoengineering. The radiative forcing simulations indicate that, for our parameterization of aerosol indirect effects, up to 35% of the radiative forcing due to current levels of greenhouse gases could be offset by stratocumulus modification. Equilibrium simulations with the atmosphere/mixed‐layer ocean model, wherein each of the three stratocumulus sheets is modified in turn, reveal that the most efficient cooling per unit radiative forcing occurs when the South Pacific stratocumulus sheet is modified. Transient coupled model simulations suggest that geoengineering all three stratocumulus areas delays the simulated global warming by about 25 years. These simulations also indicate that, while some areas experience increases in precipitation and net primary productivity, sharp decreases are simulated in South America, with particularly detrimental impacts on the Amazon rain forest. These results show that, while some areas benefit from geoengineering, there are significant areas where the response could be very detrimental with implications for the practical applicability of such a scheme.
Global pattern of temperature sensitivity of soil heterotrophic respiration (Q10) and its implications for carbon‐climate feedback
Authors: Zhou Tao , Shi Peijun , Hui Dafeng , Luo Yiqi
Published: May 2009

Temperature sensitivity of soil respiration (Q10) is an important parameter in modeling effects of global warming on ecosystem carbon release. Experimental studies of soil respiration have ubiquitously indicated that Q10 has high spatial heterogeneity. However, most biogeochemical models still use a globally constant Q10 in projecting future climate change, partly because no spatial pattern of Q10 values has been derived. In this study, we conducted an inverse analysis to retrieve a global pattern of spatially heterogeneous Q10 values by assimilating data of soil organic carbon into a process‐based terrestrial carbon model (Carnegie‐Ames‐Stanford Approach model) at spatial resolution of 1° by 1°. The estimated Q10 values were, in turn, incorporated into soil respiration models to evaluate their impacts on global respiratory carbon release from soil (i.e., total soil respiration is equal to microbial and root respiration) and from microbial decomposition (i.e., heterotrophic respiration). Our results show that the optimized Q10 values are spatially heterogeneous and vary with environmental factors. In general, Q10 value tends to be high in the high‐latitudinal regions. The mean Q10 values for different biomes range from 1.43 to 2.03, with the highest value in tundra and the lowest value in deserts. When spatially heterogeneous Q10 values were incorporated into global soil respiration models, simulated soil respiration has a feedback intensity of 3.21 Pg C °C−1 to climate warming, which is approximately 40% higher than that with a globally invariant Q10 value. The modeled heterotrophic respiration has a feedback intensity of 2.26 Pg C °C−1, about 25% higher than that derived from a globally invariant Q10 value. Overall, the feedback intensity of soil carbon release to climate warming depends not only on the magnitude of a global mean of Q10 values but also their spatial variability.
Systematic biases in subduction zone hypocenters
Authors: Syracuse Ellen M. , Abers Geoffrey A.
Published: May 2009

Earthquake hypocenters from global datasets commonly have regional biases in their locations due to the use of a one‐dimensional velocity model in their location. To analyze this effect, we group intermediate‐depth earthquakes into forty‐four 500‐km‐long sections of subduction zone. We relocate earthquakes in each group relative to one another and in a three‐dimensional global velocity model. Hypocenters shift up to 25 km regionally when these effects are included; most earthquakes in circum‐Pacific subduction zones are pulled toward the Pacific. Location uncertainties from the relative relocations are reduced to one‐fifth of those from single‐event locations; Wadati‐Benioff zone thicknesses are reduced to two‐thirds of their original thickness. These biases alter estimates of depth to slab beneath arc volcanoes up to 50 km, and alter measurements such as the volume of mantle wedge available for water storage or melt generation, and the size of the thrust zone on which large earthquakes can occur.
How good are ocean buoy observations of radiative fluxes?
Authors: Pinker Rachel T. , Wang Hengmao , Grodsky Semyon A.
Published: May 2009

Satellite‐derived surface shortwave radiation (SWR) has been extensively evaluated against ground observations over land but to a lesser extent over oceans that cover larger portion of the Earth surface. In this study new surface radiative flux estimates from the Moderate Resolution Imaging Spectro‐radiometer (MODIS) are evaluated against buoy measurements of downwelling SWR in the tropical oceans. As a benchmark for achievable accuracies from satellites, similar evaluation is performed over land against the Baseline Surface Radiation Network (BSRN) observations, believed to be of highest available quality. Comparable accuracy of the new satellite SWR data is found over land and over oceans.
Substorm current wedge driven by plasma flow vortices: THEMIS observations
Authors: Keiling A. , Angelopoulos V. , Runov A. , Weygand J. , Apatenkov S. V. , Mende S. , McFadden J. , Larson D. , Amm O. , Glassmeier K.‐H. , Auster H. U.
Published: May 2009

A multipoint analysis of conjugate magnetospheric and ionospheric flow vortices during the formation of the substorm current wedge (SCW) on 19 February 2008 is presented. During the substorm, four Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft were located close to the neutral sheet in the premidnight region between 9 and 12 RE geocentric distance, of which three closely (∼1–2 RE) clustered at ∼23 MLT and one was farther west at ∼21 MLT. The closely clustered spacecraft were engulfed by a counterclockwise plasma flow vortex, while the single spacecraft recorded a clockwise plasma flow vortex. Simultaneously, a pair of conjugate flow vortices with clockwise and counterclockwise rotation appeared in the ionosphere, as inferred from equivalent ionospheric currents. The counterclockwise space vortex, which corresponded to a downward field‐aligned current, was at least 1–2 RE in diameter and had rotational flow speeds of up to 900 km/s. Current density estimates associated with the formation of the space vortex in the first 30 s yielded 2.8 nA/m2 (14 μA/m2 mapped to the ionosphere), or a total current of 1.1 × 105 A. Model calculations based on midlatitude ground magnetometer data show a gradual increase of the field‐aligned current, with 1–2 × 105 A within the first minute and a peak value of 7 × 105 A after 10 min, associated with the SCW, and a matching meridian of the downward current of the SCW and the downward current (counterclockwise) space vortex. The combined ground and space observations, together with the model results, present a scenario in which the space vortices generated the field‐aligned current of the SCW at the beginning of the substorm expansion phase and coupled to the ionosphere, causing the ionospheric vortices.
Study of the long‐term variability of interplanetary plasma and fields as a link for solar‐terrestrial relationships
Authors: Charan Dwivedi Vidya , Tiwari D. P. , Agrawal S. P.
Published: May 2009

Often the interplanetary parameters used for the study of solar‐terrestrial relationships are solar wind speed (V), the total interplanetary magnetic field (B), and the southward component of IMF (Bz). Both hourly and daily values of these parameters have usually been employed to associate with parameters defining terrestrial effects. For our study, we have used the daily values of the interplanetary indices (V, B, and Bz), as well as the daily values of the geomagnetic disturbance index Ap, for the years 1965–2007. The long‐term averages have been calculated for the days when simultaneous data are available for all the four parameters (V, B, Bz, and Ap). These include their yearly averages, as well as the averages on the basis of the phases of the solar activity cycle. The statistical relationship between them has been investigated on these long‐term averages, as well as on the day‐to‐day basis. These sets have been further divided and studied on the basis of days with Bz being <0 or ≥0. The results obtained can be summarized as follows: (1) the magnitudes of the values of Ap are observed to be always enhanced significantly for the case of Bz < 0, as compared to days with Bz ≥ 0, and (2) V versus Ap has always low values of correlation coefficient (r). (3) On the contrary, B versus Ap has high values of “r”; (4) the product of V and B versus Ap always yields much better correlations than for V or B alone, either on an average basis or on a day‐to‐day basis, and (5) although, the long‐term variations of V are not very significant, the variations of B follow solar activity cycle and has a continuously increasing trend during the solar cycles 20 and 21. The statistical results obtained here signify that the product of V and B is more significantly effective in producing large‐scale geomagnetic disturbances.