bluuebunny/crossref_metadata_2025 huggingface dataset:
Proteomic Analysis of
Vibrio cholerae
in Human Stool
Authors: LaRocque Regina C. , Krastins Bryan , Harris Jason B. , Lebrun Lauren M. , Parker Kenneth C. , Chase Michael , Ryan Edward T. , Qadri Firdausi , Sarracino David , Calderwood Stephen B.
Published: July 2008

An effective vaccine for
Vibrio cholerae
is not yet available for use in the developing world, where the burden of cholera disease is highest. Characterizing the proteins that are expressed by
V. cholerae
in the human host environment may provide insight into the pathogenesis of cholera and assist with the development of an improved vaccine. We analyzed the
V. cholerae
proteins present in the stools of 32 patients with clinical cholera. The
V. cholerae
outer membrane porin, OmpU, was identified in all of the human stool samples, and many
V. cholerae
proteins were repeatedly identified in separate patient samples. The majority of
V. cholerae
proteins identified in human stool are involved in protein synthesis and energy metabolism. A number of proteins involved in the pathogenesis of cholera, including the A and B subunits of cholera toxin and the toxin-coregulated pilus, were identified in human stool. In a subset of stool specimens, we also assessed which in vivo expressed
V. cholerae
proteins were recognized uniquely by convalescent-phase as opposed to acute-phase serum from cholera patients. We identified a number of these in vivo expressed proteins as immunogenic during human infection. To our knowledge, this is the first characterization of the proteome of a pathogenic bacteria recovered from a natural host.
ACandida albicansMannoprotein Deprived of Its Mannan Moiety Is Efficiently Taken Up and Processed by Human Dendritic Cells and Induces T-Cell Activation without Stimulating Proinflammatory Cytokine Production
Authors: Pietrella Donatella , Lupo Patrizia , Rachini Anna , Sandini Silvia , Ciervo Alessandra , Perito Stefano , Bistoni Francesco , Vecchiarelli Anna
Published: July 2008

Mannoproteins are cell wall components of pathogenic fungi and play major virulence and immunogenic roles with both their mannan and protein moieties. The 65-kDa mannoprotein (MP65) ofCandida albicansis a β-glucanase adhesin recognized as a major target of the human immune response against this fungus, and its recombinant product (rMP65; devoid of the mannan moiety) is presently under consideration as a vaccine candidate. Here we investigated cellular and molecular aspects of the interaction of rMP65 with human antigen-presenting cells. We also assessed the ability of rMP65 to initiate a T-cell response. Both the native mannosylated MP65 (nMP65) and the recombinant product were efficiently bound and taken up by macrophages and dendritic cells. However, contrarily to nMP65, rMP65 did not induce tumor necrosis factor alpha and interleukin-6 release from these cells. On the other hand, rMP65 was rapidly endocytosed by both macrophages and dendritic cells, in a process involving both clathrin-dependent and clathrin-independent mechanisms. Moreover, the RGD sequence inhibited rMP65 uptake to some extent. After internalization, rMP65 partially colocalized with lysosomal membrane-associated glycoproteins 1 and 2. This possibly resulted in efficient protein degradation and presentation to CD4+T cells, which proliferated and produced gamma interferon. Collectively, these results demonstrate that the absence of the mannan moiety does not deprive MP65 of the capacity to initiate the pattern of cellular and molecular events leading to antigen presentation and T-cell activation, which are essential features for further consideration of MP65 as a potential vaccine candidate.
The Interleukin-17 Receptor Plays a Gender-Dependent Role in Host Protection againstPorphyromonas gingivalis-Induced Periodontal Bone Loss
Authors: Yu Jeffrey J. , Ruddy Matthew J. , Conti Heather R. , Boonanantanasarn Kanitsak , Gaffen Sarah L.
Published: July 2008

Interleukin-17 (IL-17) is a proinflammatory cytokine secreted by the newly described CD4+Th17 subset, which is distinct from classic Th1 and Th2 lineages. IL-17 contributes to bone destruction in rheumatoid arthritis but is essential in host defense against pathogens that are susceptible to neutrophils. Periodontal disease (PD) is a chronic inflammatory condition initiated by anaerobic oral pathogens such asPorphyromonas gingivalis, and it is characterized by host-mediated alveolar bone destruction due primarily to the immune response. The role of IL-17 in PD is controversial. Whereas elevated IL-17 levels have been found in humans with severe PD, we recently reported that female C57BL/6J mice lacking the IL-17 receptor (IL-17RAKO) are significantly more susceptible to PD bone loss due to defects in the chemokine-neutrophil axis (J. J. Yu, M. J. Ruddy, G. C. Wong, C. Sfintescu, P. J. Baker, J. B. Smith, R. T. Evans, and S. L. Gaffen, Blood109:3794-3802, 2007). Since different mouse strains exhibit differences in susceptibility to PD as well as Th1/Th2 cell skewing, we crossed the IL-17RA gene knockout onto the BALB/c background and observed a similar enhancement in alveolar bone loss followingP. gingivalisinfection. Unexpectedly, in both strains IL-17RAKOfemale mice were much more susceptible to PD bone loss than males. Moreover, female BALB/c-IL-17RAKOmice were defective in producing anti-P. gingivalisimmunoglobulin G and the chemokines KC/Groα and MIP-2. In contrast, male mice produced normal levels of chemokines and anti-P. gingivalisantibodies, but they were defective in granulocyte colony-stimulating factor upregulation. This study demonstrates a gender-dependent effect of IL-17 signaling and indicates that gender differences should be taken into account in the preclinical and clinical safety testing of anti-IL-17 biologic therapies.
Drosophila melanogaster-Based Screening for Multihost Virulence Factors ofPseudomonas aeruginosaPA14 and Identification of a Virulence-Attenuating Factor, HudA
Authors: Kim Seol-Hee , Park Shin-Young , Heo Yun-Jeong , Cho You-Hee
Published: July 2008

Pseudomonas aeruginosais an important opportunistic human pathogen that interacts with phylogenetically diverse nonmammalian hosts, including plants, nematodes, and insects. Here, we exploited theP. aeruginosa-induced killing of the fruit flyDrosophila melanogasteras an assay system to screen for virulence-attenuated mutants ofP. aeruginosaPA14. Fifteen nonredundant mutants were isolated from 4,018 random transposon (TnphoA) insertion clones, and 13 out of them (86.7%) displayed significantly reduced virulence in a murine peritonitis model as well. The TnphoAinsertion sites of the 15 mutants were determined; already known virulence genes (dsbA,pvdI,fhlB,pilF, andwspF) and new virulence genes such as PA0253 (hudR), PA0369, PA2077, PA0272, PA2113, PA2965 (fabF1), and PA2002 were identified; one insertion was located at the intergenic region between PA1928 and PA1929; and the other two insertions were located in the genes (PA14_35740 and PA14_36000) within a putative genomic island, indicating a potential pathogenicity island of PA14. Further characterization ofhudR, a virulence gene which encodes a MarR/SlyA family transcription factor, revealed that elevated expression of PA0254 (hudA[homologous toUbiD]) was necessary and sufficient for the virulence attenuation of thehudRmutant. The HudR protein repressed thehudARoperon by directly binding to its upstream promoter region. Collectively, these results validate the relevance of theD. melanogastermodel for the high-throughput identification of new virulence factors involved in the multihost pathogenesis ofP. aeruginosa.
ONLINE CLUSTERING ALGORITHMS
Authors: BARBAKH WESAM , FYFE COLIN
Published: July 2008

We introduce a set of clustering algorithms whose performance function is such that the algorithms overcome one of the weaknesses of K-means, its sensitivity to initial conditions which leads it to converge to a local optimum rather than the global optimum. We derive online learning algorithms and illustrate their convergence to optimal solutions which K-means fails to find. We then extend the algorithm by underpinning it with a latent space which enables a topology preserving mapping to be found. We show visualisation results on some standard data sets.
IMPROVEMENT OF IMAGE CLASSIFICATION USING WAVELET COEFFICIENTS WITH STRUCTURED-BASED NEURAL NETWORK
Authors: ZOU WEIBAO , CHI ZHERU , LO KING CHUEN
Published: July 2008

Image classification is a challenging problem in organizing a large image database. However, an effective method for such an objective is still under investigation. A method based on wavelet analysis to extract features for image classification is presented in this paper. After an image is decomposed by wavelet, the statistics of its features can be obtained by the distribution of histograms of wavelet coefficients, which are respectively projected onto two orthogonal axes, i.e., x and y directions. Therefore, the nodes of tree representation of images can be represented by the distribution. The high level features are described in low dimensional space including 16 attributes so that the computational complexity is significantly decreased. 2800 images derived from seven categories are used in experiments. Half of the images were used for training neural network and the other images used for testing. The features extracted by wavelet analysis and the conventional features are used in the experiments to prove the efficacy of the proposed method. The classification rate on the training data set with wavelet analysis is up to 91%, and the classification rate on the testing data set reaches 89%. Experimental results show that our proposed approach for image classification is more effective.
ROBUST EXPONENTIAL STABILITY OF MARKOVIAN JUMPING NEURAL NETWORKS WITH TIME-VARYING DELAY
Authors: GAO MING , LOU XUYANG , CUI BAOTONG
Published: July 2008

This paper considers the robust stability of a class of neural networks with Markovian jumping parameters and time-varying delay. By employing a new Lyapunov–Krasovskii functional, a sufficient condition for the global exponential stability of the delayed Markovian jumping neural networks is established. The proposed condition is also extended to the uncertain cases, which are shown to be the improvement and extension of the existing ones. Finally, the validity of the results are illustrated by an example.
GEOMETRIC ENGINEERING LIMIT AND WEAK GRAVITY CONJECTURE
Authors: EGUCHI TOHRU , TACHIKAWA YUJI
Published: July 2008

We analyze the coupled [Formula: see text] supergravity and Yang-Mills system using holomorphy, near the rigid limit where the former decouples from the latter. We find that there appears generically a new mass scale around gMpl where g is the gauge coupling constant and Mpl is the Planck scale. This is in accord with the weak-gravity conjecture proposed recently.
COVARIANT ENTANGLEMENT ENTROPY
Authors: TAKAYANAGI TADASHI
Published: July 2008

We review our recent formulation1,2 of computing entanglement entropy in a holographic way. The basic examples can be found by applying AdS/CFT correspondence and the holographic formula has successfully been checked in many examples of conformal field theories. We also explain the covariant formulation of holographic entanglement entropy which is closely related to the covariant entropy bound (Bousso bound) in an interesting way.
LONG OPEN STRING AND NON-SINGLET SECTOR IN MATRIX QUANTUM MECHANICS
Authors: MATSUO YUTAKA
Published: July 2008

Recently Maldacena conjectured that the long folded open string in noncritical string theory is described by the non-singlet sectors of matrix quantum mechanics. In this paper, we first describe how to obtain the exact wave functions of this system when the sign of the potential is reverted, based on a work with Y. Hatsuda. The wave functions are labeled by three Young diagrams and the degeneracy associated with it is given by the group theoretical quantities. In the second part, based on a work with J.-E. Bourgine, K. Hosomichi and I. Kostov, we derive the scattering amplitude of two long strings and which coincides with the result from the Liouville theory. It generalizes the result of the one-body scattering by Kostov and uses the relation with the two-matrix model correlation functions.
TOWARDS (DE)CONSTRUCTING 4D YANG-MILLS THEORY
Authors: FUKUMA MASAFUMI , KATAYAMA KEN-ICHI
Published: July 2008

We investigate 3D Yang-Mills theory coupled to an adjoint scalar, which can be regarded as a zeroth order approximation in (de)constructing 4D Yang-Mills theory. We develop a new algorithm to obtain the renormalized Hamiltonian with the Karabali-Nair variable, by carefully identifying finite local counterterms. We also discuss how this formalism can be applied to obtain glueball spectrum.
REDUCED MODEL FOR SUPERSTRINGS ON AdSn × Sn
Authors: GRIGORIEV MAXIM , TSEYTLIN ARKADY
Published: July 2008

We review the Pohlmeyer reduction of the superstring sigma model on AdSn × Sn leading to a gauged WZW model with an integrable potential. In particular, we consider the case of GS superstrings on AdS3 × S3 supported by RR flux. The bosonic part of the reduced Lagrangian is given by the sum of the complex sine-Gordon Lagrangian and its sinh-Gordon counterpart. We determine the corresponding fermionic part and discuss possible 2d supersymmetry of the reduced action.
ALDAY-MALDACENA DUALITY AND AdS PLATEAU PROBLEM
Authors: MOROZOV A.
Published: July 2008

A short summary of approximate approach to the study of minimal surfaces in AdS, based on solving Nambu-Goto equations iteratively. Today, after partial denunciation of the BDS conjecture, this looks like the only constructive approach to understanding the ways of its possible modification and thus to saving the Alday-Maldacena duality. Numerous open technical problems are explicitly formulated throughout the text.
COMMENTS ON GLUON SCATTERING AMPLITUDES IN $\mathcal{N} = 4$ SUPER YANG-MILLS THEORY AT STRONG COUPLING
Authors: ITO KATSUSHI
Published: July 2008

We review recent developments in calculation of the gluon scattering amplitudes in [Formula: see text] super Yang-Mills theory at strong coupling via AdS/CFT correspondence. We discuss certain class of 6 and 8 point amplitudes at strong coupling, which can be obtained by cutting and gluing the 4-point amplitude.
DEFORMATION OF DIJKGRAAF-VAFA RELATION VIA SPONTANEOUSLY BROKEN $\mathcal{N} = 2$ SUPERSYMMETRY
Authors: MARUYOSHI KAZUNOBU
Published: July 2008

We review the matter induced part of the effective superpotential of [Formula: see text], U(N) gauge model in which [Formula: see text] supersymmetry is spontaneously broken to [Formula: see text]. We derive this by the diagrammatical computation and by using the properties of the chiral ring and the generalized Konishi anomaly equations.
LOCALIZED MODES IN SINGULAR CALABI-YAU CONFORMAL FIELD THEORIES
Authors: MIZOGUCHI SHUN'YA
Published: July 2008

We construct spacetime supersymmetric, modular invariant partition functions for type II and heterotic strings on the conifold-type singularities such that they include contributions coming from the discrete-series representations of SL(2, R). In particular for the E8 × E8 heterotic case, they are in the 27 representation of E6 and localized on a four-dimensional "brane" at the tip of the cigar geometry.
BRANE SUPERPOTENTIAL AND LOCAL CALABI–YAU MANIFOLDS
Authors: RICCO ANTONIO
Published: July 2008

We briefly report on some recent progresses in the computation of B-brane superpotentials for Type II strings compactified on Calabi–Yau manifolds, obtained by using a paramatrization of tubular neighborhoods of complex submanifolds, also known as local spaces. In particular, we propose a closed expression for the superpotential of a brane on a genus-g curve in a Calabi–Yau threefold for the cases in which there exists a holomorphic projection from the local space around the curve to the curve itself.
SINGULARITIES AND GAUGE-GRAVITY DUALITY
Authors: DAS SUMIT R.
Published: July 2008

We describe toy models of cosmology in asymptotically AdS space-times which have natural gauge theory duals. For spacetimes containing null singularities we argue that the gauge theory provides a well defined evolution in light front time even though the gravity description does not. For models with spacelike singularities examined so far, we identify the signature of such singularities in the gauge theory. However, it is not clear whether these singularities can be "resolved".
D-BRANES AND CLOSED STRING FIELD THEORY
Authors: ISHIBASHI NOBUYUKI , BABA YUTAKA , MURAKAMI KOICHI
Published: July 2008

We construct solitonic states in the OSp invariant string field theory, which are BRST invariant in the leading order of regularization parameter. One can show that these solitonic states describe D-branes and ghost D-branes, by calculating the scattering amplitudes.
NEAR EXTREMAL BLACK HOLE ENTROPY AS ENTANGLEMENT ENTROPY VIA AdS2/CFT1
Authors: AZEYANAGI TATSUO
Published: July 2008

We holographically derive entropy of (near) extremal black holes as entanglement entropy of conformal quantum mechanics(CQM) living in two boundaries of AdS2.
GENERAL OPERATOR SOLUTIONS AND BRST QUANTIZATION OF SUPERSTRINGS IN THE pp-WAVE WITH TORSION
Authors: CHIZAKI YOICHI , YAHIKOZAWA SHIGEAKI
Published: July 2008

We completely accomplish the canonically covariant quantization of RNS superstrings in the pp-wave background with torsion which is equivalent to the NS-NS flux. In this quantization, we construct general operator solutions which satisfy all the equations of motion and all the canonical (anti)commutation relations. Because the general operator solutions can be composed of only free modes, we also call them free-mode representations. Using the covariant free-mode representations, we calculate the anomaly in the super-Virasoro algebra and determine the number of dimensions of spacetime and ordering constant from the nilpotency condition of the BRST charge in the NS-NS pp-wave.
INTEGRABLE ASPECTS OF NONCOMMUTATIVE ANTI-SELF-DUAL YANG-MILLS EQUATIONS
Authors: HAMANAKA MASASHI
Published: July 2008

We discuss extension of soliton theory and integrable systems to non-commutative (NC) spaces, focusing on integrable aspects of NC Anti-Self-Dual Yang-Mills (ASDYM) equations. We give exact soliton solutions (with both finite- and infinite-action solutions) by means of Bäcklund transformations. In the construction of NC soliton solutions, one kind of NC determinants, quasideterminants, play crucial roles. This is partially based on collaboration with C. R. Gilson and J. J. C. Nimmo (Glasgow).
CREATION OF D9-BRANE–$\overline{{\rm D}9}$-BRANE PAIRS FROM HAGEDORN TRANSITION OF CLOSED STRINGS
Authors: HOTTA KENJI
Published: July 2008

Atick and Witten have proposed the Hagedorn transition of closed strings via condensation of 'winding tachyon'. But we have not known the stable minimum of this tachyon potential yet. On the other hand, we have previously shown that a phase transition occurs near the Hagedorn temperature and D9-brane– [Formula: see text]-brane pairs become stable. We present a conjecture that D9-brane– [Formula: see text]-brane pairs are created by the Hagedorn transition of closed strings. We will show some circumstantial evidences for this conjecture.
CASIMIR ENERGY OF 5D ELECTRO-MAGNETISM AND SPHERE LATTICE REGULARIZATION
Authors: ICHINOSE SHOICHI
Published: July 2008

Casimir energy is calculated in the 5D warped system. It is compared with the flat one. The position/ momentum propagator is exploited. A new regularization, called sphere lattice regularization, is introduced. It is a direct realization of the geometrical interpretation of the renormalization group. The regularized configuration is closed-string like. We do not take the KK-expansion approach. Instead the P/M propagator is exploited, combined with the heat-kernel method. All expressions are closed-form (not KK-expanded form). Rigorous quantities are only treated (non-perturbative treatment). The properly regularized form of Casimir energy, is expressed in the closed form. We numerically evaluate its Λ(4D UV-cutoff), ω(5D bulk curvature, warpedness parameter) and T(extra space IR parameter) dependence.
D-BRANES AND KRAMERS-WANNIER DUALITY IN NON-CRITICAL SUPERSTRING THEORY
Authors: IRIE HIROTAKA
Published: July 2008

We study boundary states in (p,q) minimal superstring theory, combining the explicit form of matter wave functions. Within the modular bootstrap framework, Cardy states of (p, q) minimal superconformal field theory are completely determined in both cases of the different supercharge combinations, and the remaining consistency checks in the super-Liouville case are also performed. Using these boundary states, we determine the explicit form of FZZT- and ZZ-brane boundary states both in each GSO projection. Annulus amplitudes of FZZT branes are evaluated and principal FZZT branes are identified. In particular, we found that these principal FZZT branes do not satisfy Cardy's consistency conditions for each other and play a role of order/disorder parameters of a Kramers-Wannier duality in spacetime of this superstring theory. This presentation is based on the paper1.
BOUNDARY STATE OF SUPERSTRING IN OPEN STRING CHANNEL
Authors: IMAMURA YOSUKE , ISONO HIROSHI , MATSUO YUTAKA
Published: July 2008

We report on the boundary state of superstring in the open string channel, which describes the superconformal field theory of open string emission and absorption by D-brane.
THE BV MASTER EQUATION FOR THE WILSON ACTION IN GENERAL YANG-MILLS GAUGE THEORY
Authors: HIGASHI TAKESHI , ITOU ETSUKO , KUGO TAICHIRO
Published: July 2008

We study the four dimensional gauge theory within Wilsonian Renormalization Group (WRG) method. The Wilson effective action for general Yang-Mills gauge theory is shown to satisfy the usual form of Batalin-Vilkovisky (BV) master equation, despite that a momentum cutoff apparently breaks the gauge invariance. In the case of Abelian gauge theory, in particular, it actually deduces the Ward-Takahashi identity for Wilson action recently derived by Sonoda. We elucidated the relation of our Wilson master action with that derived by Ref. 2 and, in particular, showed that our BV Master equation really reproduced the Sonoda's WT identity for the Wilson action in QED. (This is a proceeding to the conference based on the poster given by E.I.).
INDEX THEOREMS ON TORSIONAL GEOMETRIES
Authors: KIMURA TETSUJI
Published: July 2008

We investigate the Atiyah-Singer index theorems with torsion given by Neveu-Schwarz three-form flux H under the condition d H = 0 in flux compactification scenarios with non-trivial background fields in string theories. Using an identification between the Clifford algebra on the geometry and the canonical quantization condition in [Formula: see text] quantum mechanics, we explicitly reformulate the Dirac index on manifolds with torsion, which will provides a fundamental information to effective theories derived from string theory. In the same analogy we also reformulate the Euler characteristics and the Hirzebruch signatures in the framework of [Formula: see text] quantum mechanics.
DYNAMICS OF DOMAIN WALL NETWORKS
Authors: NAGASHIMA TAKAYUKI
Published: July 2008

Networks or webs of domain walls are admitted in Abelian or non-Abelian gauge theory coupled to fundamental Higgs fields with complex masses. We examine the dynamics of the domain wall loops by using the moduli space approximation. This talk is based on works in collaboration with M.Eto, T.Fujimori, M.Nitta, K.Ohashi, and N.Sakai1,2.
HOLOGRAPHY OF NON-RELATIVISTIC STRING ON AdS5 × S5
Authors: SAKAGUCHI MAKOTO , YOSHIDA KENTAROH
Published: July 2008

We briefly review a holography of non-relativistic (NR) string on AdS 5× S 5. The NR string can be regarded as a semiclassical string around an AdS2 classical solution corresponding to a straight Wilson line in the gauge-theory side. Exciting non-normalizable modes of the NR string gives source term insertions on the Wilson line. For normalizable modes we discuss a relation to a conformal quantum mechanics.
COMMENTS ON ORIENTIFOLD OF BRANE TILINGS
Authors: IMAMURA YOSUKE , KIMURA KEISUKE , YAMAZAKI MASAHITO
Published: July 2008

The relation between brane charge conservation law in fivebrane system described by orientifolded brane tilings and the gauge anomaly cancellation in the corresponding gauge theories is summarized.
THE MICROSCOPIC APPROACH TO $\mathcal{N} = 1$ SUPER YANG-MILLS THEORIES
Authors: FERRARI FRANK
Published: July 2008

We give a brief account of the recent progresses in super Yang-Mills theories based in particular on the application of Nekrasov's instanton technology to the case of [Formula: see text] supersymmetry. We have developed a first-principle formalism from which any chiral observable in the theory can be computed, including in strongly coupled confining vacua. The correlators are first expressed in terms of some external variables as sums over colored partitions. The external variables are then fixed to their physical values by extremizing the microscopic quantum superpotential. Remarquably, the results can be shown to coincide with the Dijkgraaf-Vafa matrix model approach, which uses a totally different mathematical framework. These results clarify many important properties of [Formula: see text] theories, related in particular to generalized Konishi anomaly equations and to Veneziano-Yankielowicz terms in the glueball superpotentials. The proof of the equivalence between the formalisms based on colored partitions and on matrices is also a proof of the open/closed string duality in the chiral sector of the theories.
REFINED INSTANTON COUNTING AND MACDONALD FUNCTIONS
Authors: KANNO HIROAKI
Published: July 2008

We argue that the Nekrasov's partition function with two equivariant parameters is reproduced by the method of topological vertex, if we introduce a refined version of the vertex. Our refined topological vertex is expressed in terms the specialization of the Macdonald functions which is related to the equivariant character of the Hilbert scheme of ℂ2. We provide diagrammatic rules for computing the partition function.
INTEGRABLE STRUCTURE OF 5d$\mathcal{N} = 1$ SUPERSYMMETRIC YANG-MILLS AND MELTING CRYSTAL
Authors: NAKATSU TOSHIO , NOMA YUI , TAKASAKI KANEHISA
Published: July 2008

We study loop operators of 5d[Formula: see text] SYM in Ω background. Computation of their correlation functions is described. For the case of U(1) theory, the generating function reproduces the partition function of melting crystal model with external potential. We argue the common integrable structure of 5d[Formula: see text] SYM in Ω background and melting crystal model. An extension of the Seiberg-Witten geometry of the U(1) theory is presented.
AN ATTEMPT TOWARDS FIELD THEORY OF D0 BRANES — QUANTUM M-FIELD THEORY
Authors: YONEYA TAMIAKI
Published: July 2008

I discuss my recent attempt in search of a new framework for quantum field theory of D branes. After explaining some motivations in the background of this project, I present, as a first step towards our goal, a second-quantized reformulation of the U (N) Yang-Mills quantum mechanics in which the D0-brane creation-and-annihilation fields connecting theories with different N are introduced. Physical observables are expressed in terms of bilinear forms of the D0 fields. The large N limit is briefly treated using this new formalism.
OPTIMAL SUPERHEDGING UNDER NON-CONVEX CONSTRAINTS — A BSDE APPROACH
Authors: BENDER CHRISTIAN , KOHLMANN MICHAEL
Published: July 2008

We apply theoretical results by Peng on supersolutions for Backward SDEs (BSDEs) to the problem of finding optimal superhedging strategies in a generalized Black–Scholes market under constraints. Constraints may be imposed simultaneously on wealth process and portfolio. They may be non-convex, time-dependent, and random. The BSDE method turns out to be an extremely useful tool for modeling realistic markets: in this paper, it is shown how more realistic constraints on the portfolio may be formulated via BSDE theory in terms of the amount of money invested, the portfolio proportion, or the number of shares held. Based on recent advances on numerical methods for BSDEs (in particular, the forward scheme by Bender and Denk [1]), a Monte Carlo method for approximating the superhedging price is given, which demonstrates the practical applicability of the BSDE method. Some numerical examples concerning European and American options under non-convex borrowing constraints are presented.
FOURIER TRANSFORM METHOD WITH AN ASYMPTOTIC EXPANSION APPROACH: AN APPLICATION TO CURRENCY OPTIONS
Authors: TAKAHASHI AKIHIKO , TAKEHARA KOHTA
Published: July 2008

This paper develops a Fourier transform method with an asymptotic expansion approach for option pricing. The method is applied to European currency options with a libor market model of interest rates and jump-diffusion stochastic volatility models of spot exchange rates. In particular, we derive closed-form approximation formulas of the characteristic functions of log-prices of the underlying assets and the prices of currency options based on a third order asymptotic expansion scheme; we use a jump-diffusion model with a mean-reverting stochastic variance process such as in Heston [7]/Bates [1] and log-normal market models for domestic and foreign interest rates. Finally, the validity of our method is confirmed through numerical examples.
HEDGING UNDER THE HESTON MODEL WITH JUMP-TO-DEFAULT
Authors: CARR PETER , SCHOUTENS WIM
Published: July 2008

In this paper, we will explain how to perfectly hedge under Heston's stochastic volatility model with jump-to-default, which is in itself a generalization of the Merton jump-to-default model and a special case of the Heston model with jumps. The hedging instruments we use to build the hedge will be as usual the stock and the bond, but also the Variance Swap (VS) and a Credit Default Swap (CDS). These instruments are very natural choices in this setting as the VS hedges against changes in the instantaneous variance rate, while the CDS protects against the occurrence of the default event.

First, we explain how to perfectly hedge a power payoff under the Heston model with jump-to-default. These theoretical payoffs play an important role later on in the hedging of payoffs which are more liquid in practice such as vanilla options. After showing how to hedge the power payoffs, we show how to hedge newly introduced Gamma payoffs and Dirac payoffs, before turning to the hedge for the vanillas. The approach is inspired by the Post–Widder formula for real inversion of Laplace transforms. Finally, we will also show how power payoffs can readily be used to approximate any payoff only depending on the value of the underlier at maturity. Here, the theory of orthogonal polynomials comes into play and the technique is illustrated by replicating the payoff of a vanilla call option.
EARLY EXPERIENCES WITH THE 360TF IBM BLUE GENE/L PLATFORM
Authors: BHANOT G. , DENNIS J. M. , EDWARDS J. , GRABOWSKI W. , GUPTA M. , JORDAN K. , LOFT R. D. , SEXTON J. , ST-CYR A. , THOMAS S. J. , TUFO H. M. , VORAN T. , WALKUP R. , WYSZOGRODSKI A. A.
Published: July 2008

The High Order Method Modeling Environment is a scalable, spectral-element-based prototype for the Community Atmospheric Model component of the Community Climate System Model. The 3D moist primitive equations are solved on the cubed sphere with a hybrid pressure η vertical coordinate using an Emanuel convective parametrization for moist processes. Semi-implicit time integration, based on a preconditioned conjugate gradient solver, circumvents the time step restrictions associated with gravity waves. Benchmarks for two standard tests problems at 10 km horizontal resolution have been run on Blue Gene/L. Results obtained on a 32-rack Blue Gene/L system (65,536 processors, 183.5-teraflop peak) show sustained performance of 8.0 teraflops on 32,768 processors for the moist Held–Suarez test problem in coprocessor mode and 11.3 teraflops on 32,768 processors for the aquaplanet test problem, running in virtual node mode.
SPARSE APPROXIMATE INVERSE PRECONDITIONER FOR CONTACT PROBLEMS ON THE EARTH SIMULATOR USING OPENMP
Authors: NAKAJIMA KENGO
Published: July 2008

In this study, the sparse approximate inverse (SAI) preconditioning method is applied to a single SMP node of the Earth Simulator (ES) using OpenMP. The developed method is tested for applications with contact conditions, and demonstrates efficiency and robustness for a wide range of problem sizes. The efficiency and robustness of the SAI preconditioner is competitive with that of the selective blocking method, which is a special preconditioning method for contact problems. The developed method is ported to Hitachi SR8000 and IBM SP-3, and the performance and robustness is evaluated.
GRID SIMULATION SERVICES FOR THE MEDICAL COMMUNITY
Authors: BERTI GUNTRAM , LONSDALE GUY , SCHMIDT JENS GEORG , BENKNER SIEGFRIED , HOSE D. RODNEY , FENNER JOHN W. , JONES DAVID M. , MIDDLETON STUART E. , WOLLNY GERT
Published: July 2008

The first part of this paper presents a selection of medical simulation applications, including image reconstruction, near-real-time registration for neuro-surgery, enhanced dose distribution calculation for radiotherapy, inhaled drug delivery prediction, plastic surgery planning and cardio-vascular system simulation. The latter two topics are discussed in some detail. In the second part, we show how such services can be made available to the clinical practitioner using grid technology. We discuss the developments made and the experience gained during the EU project GEMSS, which provides reliable, efficient, secure and lawful medical grid services.
ISOMORPHISM AND INVERSIONS OF KINEMATIC CHAINS UP TO TEN LINKS USING DEGREES OF FREEDOM OF KINEMATIC PAIRS
Authors: HASAN ALI , KHAN R. A.
Published: July 2008

This paper presents a new method for identifying the distinct mechanisms (DMs) from a given kinematic chain (KC). The KCs are represented in the form of the weighted physical connectivity matrix (WPCM). Two structural invariants derived from the characteristic polynomials of the WPCM of the KC are the sum of absolute characteristic polynomial coefficients (∑WPCM) and the maximum absolute value of the characteristic polynomial coefficient (MWPCM). They have been used as the composite identification number of a KC and mechanism. This is capable of detecting DMs in all types of simple jointed planar KCs up to ten links having the same or different kinematic pairs (KPs). The proposed method has been tested successfully in identifying all the DMs derived from the family of single degree of freedom (dof) KCs up to ten links. Also, it does not require any test for isomorphism separately. This study will help the designer to select the best KC and mechanisms to perform the specified task at the conceptual stage of design.
A GENERALIZED GRADIENT SMOOTHING TECHNIQUE AND THE SMOOTHED BILINEAR FORM FOR GALERKIN FORMULATION OF A WIDE CLASS OF COMPUTATIONAL METHODS
Authors: LIU G. R.
Published: July 2008

This paper presents a generalized gradient smoothing technique, the corresponding smoothed bilinear forms, and the smoothed Galerkin weakform that is applicable to create a wide class of efficient numerical methods with special properties including the upper bound properties. A generalized gradient smoothing technique is first presented for computing the smoothed strain fields of displacement functions with discontinuous line segments, by "rudely" enforcing the Green's theorem over the smoothing domain containing these discontinuous segments. A smoothed bilinear form is then introduced for Galerkin formulation using the generalized gradient smoothing technique and smoothing domains constructed in various ways. The numerical methods developed based on this smoothed bilinear form will be spatially stable and convergent and possess three major important properties: (1) it is variationally consistent, if the solution is sought in a Hilbert space; (2) the stiffness of the discretized model will be reduced compared to the model of the finite element method (FEM) and often the exact model, which allows us to obtain upper bound solutions with respect to both the FEM solution and the exact solution; (3) the solution of the numerical method developed using the smoothed bilinear form is less insensitive to the quality of the mesh, and triangular meshes can be used perfectly without any problems. These properties have been proved, examined, and confirmed by the numerical examples. The smoothed bilinear form establishes a unified theoretical foundation for a class of smoothed Galerkin methods to analyze solid mechanics problems for solutions of special and unique properties: the node-based smoothed point interpolation method (NS-PIM), smoothed finite element method (SFEM), node-based smoothed finite element method (N-SFEM), edge-based smoothed finite element method (E-SFEM), cell-based smoothed point interpolation method (CS-PIM), etc.
Frictional-viscous flow, seismicity and the geology of weak faults: a review and future directions
Authors: Imber J. , Holdsworth R. E. , Smith S. A. F. , Jefferies S. P. , Collettini C.
Published: July 2008

Previously hypothesized fault weakening mechanisms include faults lined by low-friction clay gouges, elevated pore pressures within fault cores and/or the operation of dynamic weakening during seismic slip. Geological studies to support dynamic weakening are still in their infancy and there is little geological evidence for the widespread occurrence of low-friction gouges. The cores of some ancient faults exhumed from <5 km depth contain sheared syntectonic mineral veins. This observation is consistent with elevated pore pressures, but the implications for long-term fault weakening are unclear. Experimental data and microphysical modelling suggest that frictional–viscous flow within phyllosilicate-rich fault rocks (phyllonites, some foliated cataclasites) can cause sufficient weakening of crustal faults to satisfy published heat flow constraints. These predictions are consistent with the common occurrence of phyllonite in the cores of large-displacement faults exhumed from >5 km depth. Comparison with seismological data suggests that some faults with phyllonitic cores are likely to generate large earthquakes. Future studies should establish the geological evidence for seismic slip within phyllonitic fault cores and quantify the partitioning between seismic slip and frictional–viscous flow. Further geological observations are also required to test the hypothesized mechanisms by which earthquakes can nucleate and propagate along phyllosilicate-rich faults.
Fault weakening due to CO
2
degassing in the Northern Apennines: short- and long-term processes
Authors: Collettini C. , Cardellini C. , Chiodini G. , De Paola N. , Holdsworth R. E. , Smith S. A. F.
Published: July 2008

The influx of fluids into fault zones can trigger two main types of weakening process that operate over different timescales and facilitate fault movement and earthquake nucleation. Short- and long-term weakening mechanisms along faults require a continuous fluid supply near the base of the brittle crust, a condition satisfied in the extended/extending area of the Northern Apennines of Italy. Here carbon mass balance calculations, coupling aquifer geochemistry to isotopic and hydrological data, define the presence of a large flux (
c
. 12 160 t/day) of deep-seated CO
2
centred in the extended sector of the area. In the currently active extending area, CO
2
fluid overpressures at ∼85% of the lithostatic load have been documented in two deep (4–5 km) boreholes. In the long-term, field studies on an exhumed regional low-angle normal fault show that, during the entire fault history, fluids reacted with fine-grained cataclasites in the fault core to produce aggregates of weak, phyllosilicate-rich fault rocks that deform by fluid assisted frictional–viscous creep at sub-Byerlee friction values (μ<0.3). In the short term, fluids can be stored in structural traps, such as beneath mature faults, and stratigraphical traps such as Triassic evaporites. Both examples preserve evidence for multiple episodes of hydrofracturing induced by short-term cycles of fluid pressure build-up and release. Geochemical data on the regional-scale CO
2
degassing process can therefore be related to field observations on fluid rock interactions to provide new insights into the deformation processes responsible for active seismicity in the Northern Apennines.
Deformation partitioning within a sinistral transpression zone along the southwestern margin of the Tauern Window (eastern Alps)
Authors: Wölfler Andreas , Rabitsch Robert , Fritz Harald , Gaich Heiko , Kurz Walter , Reiter Angelika
Published: July 2008

This study is concerned with a newly recognized structure at the southwestern border of the Tauern Window and the neighbouring Austroalpine basement rocks, the Lappach Structure. Structural and isotopic investigations show that this structure is the result of sinistral transpression and backthrusting along the Austroalpine–Penninic contact. Deformation partitioning and differential exhumation of crustal wedges is documented by a succession of ductile and brittle deformation stages. Two stages are distinguished: (1) up-doming of Penninic units and associated advective heat transfer caused a strong temperature variation with the highest temperatures in central portions of the Tauern Window. Coeval transpression with distributed sinistral shear formed high-temperature, partly annealed fabrics in central portions and lower-temperature fabrics with strong crystallographic preferred orientation of quartz along the Tauern Window margin. Southward decrease of temperatures was matched by increases in stress and deformation intensity. (2) Progressive cooling was accompanied by shear localization, deformation partitioning and fluid infiltration. Overall sinistral shear resolved in a discrete strike slip–fault and south vergent folds with associated thrusts defining a backthrust zone along the southern Tauern margin. Southwards extrusion disturbed previously established palaeo-isogrades and juxtaposed rocks from greater depths against lower-grade metamorphic units. Fluids penetrated faults, reduced shear strength and contributed to shear localization.
Fluid flow properties of basin-bounding normal faults in platform carbonates, Fucino Basin, central Italy
Authors: Agosta Fabrizio
Published: July 2008

Both structural and petrophysical (porosity, ϕ, and permeability,
k
) data show that the basin-bounding normal faults of the Fucino Basin, central Italy, have a combined barrier–conduit effect on fluid flow. The deformed carbonates comprise fault cores of both matrix- and cement-supported fault rocks (low ϕ and
k
) and major slip surfaces, and damage zones of fragmented and pulverized carbonates (high ϕ and
k
) and small faults. The host rocks are Mesozoic, platform-related boundstones with low ϕ (<1%) and low
k
(<1×10
−4
mD). The results of ultrasonic analysis suggest that the fragmented carbonates contain pores with a high aspect ratio, whereas the fault rocks have pores with a low aspect ratio and some moldic porosity. These two separate fluid units are modelled as an elastic cracked medium (fragmented carbonates), and as a granular medium (fault core). By using well-known correlations, their permeability is then computed from known values of ϕ, pore radii and elastic moduli.
40
Ar/
39
Ar dating of synkinematic white mica: insights from fluid-rock reaction in low-grade shear zones (Mont Blanc Massif) and constraints on timing of deformation in the NW external Alps
Authors: Rolland Y. , Rossi M. , Cox S. F. , Corsini M. , Mancktelow N. , Pennacchioni G. , Fornari M. , Boullier A. M.
Published: July 2008

This paper highlights the use of synkinematic white mica, biotite and phlogopite for the dating of deformation in ductile shear zones within crystalline rocks under low-grade metamorphic conditions. The Mont Blanc shear zones range from 1 mm to 50 m in width and have localized intense fluid flow, resulting in substantial differences in mineralogy and whole-rock geochemistry. On the basis of their synkinematic alteration assemblages and geographic distribution within the Mont Blanc Massif, three main metamorphic zones are distinguished within the network of shear zones. These are: (i) epidote±white mica-bearing assemblages; (ii) chlorite–phlogopite-bearing assemblages; and (iii) white mica±biotite±calcite±actinolite±epidote- bearing assemblages.
40
Ar/
39
Ar age spectra of biotite and phlogopite are complex, and reflect significant variations in chemical composition. In biotite, this is partly due to inheritance from precursor Variscan magmatic biotite. In contrast, new white mica grew at the expense of feldspar during Alpine deformation and its Ar spectra do not show any excess
40
Ar. On the SE side of Mont Blanc, ages of shear zone phengites have a narrow range of 15.8–16.0±0.2 Ma, which is in the same age range as
40
Ar/
39
Ar ages of minerals from kinematically related veins. The top-to-SE sense of shear is consistent with initiation of a Mont Blanc flower-structure within a dextral transpressional system by 16 Ma. On the NW side, mini-plateaux ages of 14.5±0.3 and 23.4±0.4 Ma are preserved in the same sample, suggesting the possibility of two phases of deformation. This is also supported by partly preserved ages of 18–36.6 Ma in biotites and phlogopites. Ages between 36 and 18 Ma might reflect ongoing top-to-NW thrusting, following Penninic Front activation, in a context of nappe stacking and crustal thickening. NW-directed thrusting on the NW side of Mont Blanc continued after 18 Ma, synchronous with SE-directed thrusting on the SE side of the massif. These divergent movements produced the overall pop-up geometry of the Mont Blanc Massif, which may correspond to a positive flower structure developed within a zone of regional dextral transpression extending SW from the Rhone valley into the Mont Blanc area.
Assessment of thermal circulations in strike-slip fault systems: the Terme di Valdieri case (Italian western Alps)
Authors: Baietto A. , Cadoppi P. , Martinotti G. , Perello P. , Perrochet P. , Vuataz F.-D.
Published: July 2008

Individual faults, faults linking at depth in flower structure zones and jogs bounded by faults are common structural elements in strike–slip fault systems and can play an important role in controlling thermal fluid flows. This paper explores the influence of these structures on the thermal circulations and fluid outflows of Terme di Valdieri, in the crystalline basement of the Argentera Massif (western Alps). In this site, thermal waters upwell at the tip of a NW-trending right-lateral fault, but exactly which structures control infiltration of meteoric waters and deep circulation is not clear from field surveys. Three-dimensional thermohydraulic numerical models calculated in steady-state and in transient regimes are presented for three alternative hypotheses. These account for circulations occurring: (i) within a single fault and adjoining host rocks; (ii) in faults intersecting at depth; and (iii) in faults interacting by means of a permeable step-over. The simulations show that advective flows can coexist with convective flows in models (i) and (iii), provided that the fault permeabilities are higher than 2×10
−13
m
2
, while advection prevails in model (ii) at all values of permeability. Model (iii) achieves the best fit to the data under the assumption of advective and convective flows. This finding provides a first quantitative estimate of the importance of jog structures bounded by strike–slip faults in favouring thermal outflows. Moreover, the numerical results suggest that thermal convection can coexist with advection also in mountainous settings.