D-brane Deconstructions in IIB Orientifolds
Collinucci, Andres; Esole, Mboyo
2009-01-01
With model building applications in mind, we collect and develop basic techniques to analyze the landscape of D7-branes in type IIB compact Calabi-Yau orientifolds, in three different pictures: F-theory, the D7 worldvolume theory and D9-anti-D9 tachyon condensation. A significant complication is that consistent D7-branes in the presence of O7^- planes are generically singular, with singularities locally modeled by the Whitney Umbrella. This invalidates the standard formulae for charges, moduli space and flux lattice dimensions. We infer the correct formulae by comparison to F-theory and derive them independently and more generally from the tachyon picture, and relate these numbers to the closed string massless spectrum of the orientifold compactification in an interesting way. We furthermore give concrete recipes to explicitly and systematically construct nontrivial D-brane worldvolume flux vacua in arbitrary Calabi-Yau orientifolds, illustrate how to read off D-brane flux content, enhanced gauge groups and c...
Type IIB orientifolds, D-brane instantons and the large volume scenario
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Plauschinn, Erik
2009-07-28
This thesis is concerned with a branch of research in String Theory called String Phenomenology which aims for a better understanding of the connection between String Theory and Particle Physics. In particular, in this work we cover three topics which are important in order to establish this connection. The first topic is about String Theory model building in the context of so-called type IIB orientifolds with orientifold three- and seven-planes. After giving a brief overview, we work out in detail an important consistency condition for String Theory constructions, the so-called tadpole cancellation condition, and we verify explicitly that chiral anomalies are cancelled via the generalised Green-Schwarz mechanism. The second topic is concerned with so-called D-brane instantons which are nonperturbative effects in type II String Theory constructions. We recall the instanton calculus for such configurations, we derive the so-called A eck-Dine-Seiberg superpotential in String Theory and we develop an important constraint, a chiral zero-mode constraint, for instanton contributions in the presence of a realistic Particle Physics sector. The third topic is about moduli stabilisation in type IIB string compactifications. More concretely, we review the so-called KKLT as well as Large Volume Scenario, and we construct and study a model for the latter scenario where the constraint mentioned above has been taken into account explicitly. Although the three topics studied in this thesis are slightly different in nature, there is nevertheless a complex interplay between them with many interrelations. In order to uncover these connections, a detailed study of each individual subject has been performed which has led to new results such as the chiral zero-mode constraint. (orig.)
D-Brane Superpotential and Orientifold Projection
Diaconescu, D E; Karp, R L; Sinha, K; Diaconescu, Duiliu-Emanuel; Garcia-Raboso, Alberto; Karp, Robert L.; Sinha, Kuver
2006-01-01
We develop computational tools for the tree-level superpotential of B-branes in Calabi-Yau orientifolds. Our method is based on a systematic implementation of the orientifold projection in the geometric approach of Aspinwall and Katz. In the process we lay down some ground rules for orientifold projections in the derived category.
d-Brane Instantons in Type II Orientifolds
Blumenhagen, Ralph; Cvetič, Mirjam; Kachru, Shamit; Weigand, Timo
2009-11-01
We review recent progress in determining the effects of d-brane instantons in [Formula: see text] supersymmetric compactifications of Type II string theory to four dimensions. We describe the abstract d-brane instanton calculus for holomorphic couplings such as the superpotential, the gauge kinetic function, and higher fermionic F-terms, and we briefly discuss the implications of background fluxes for the instanton sector. We then summarize the concrete consequences of stringy d-brane instantons for the construction of semirealistic models of particle physics or supersymmetry breaking in compact and noncompact geometries.
D-branes in Type IIA and Type IIB theories from tachyon condensation
Kluson, J
2000-01-01
In this paper we will construct all D-branes in Type IIA and Type IIB theories via tachyon condensation. We also propose form of Wess-Zumino term for non-BPS D-brane and we will show that tachyon condensation in this term leads to standard Wess-Zumino term for BPS D-brane.
Type IIB orientifolds with discrete torsion
Karp, R L; Witten, Louis; Karp, Robert L; Witten, Louis
2001-01-01
We consider compact four-dimensional ${\\bf Z_N}\\times {\\bf Z_M}$ type IIB orientifolds, for certain values of $N$ and $M$. We allow the additional feature of discrete torsion and discuss the modification of the consistency conditions arising from tadpole cancellation. We point out the differences between the cases with and without discrete torsion.
Moduli stabilization in type IIB orientifolds
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Schulgin, W.
2007-06-04
This thesis deals with the stabilization of the moduli fields in the compactifications of the type IIB string theory on orientifolds. A concrete procedure for the construction of solutions, in which all moduli fields are fixed, yields the KKLT scenario. We study, on which models the scenario can be applied, if approximations of the original KKLT work are abandoned. We find that in a series of models, namely such without complex-structure moduli the construction of the consistent solutions in the framework of the KKLT scenario is not possible. The nonperturbative effects, like D3 instantons and gaugino condensates are a further component of the KKLT scenario. They lead to the stabilization of the Kaehler moduli. We present criteria for the generation of the superpotential due to the D3 instantons at a Calaby-Yau manifold in presence of fluxes. Furthermore we show that although the presence of the nonperturbative superpotential in the equations of motions is correlated with the switching on of all ISD and IASD fluxes, the deciding criterium for the generation of the nonperturbative superpotential depends only on the fluxes of the type (2,1). Thereafter we discuss two models, in which we stabilize all moduli fields. Thereby it deals with Calabi-Yau orientifolds which have been obtained by a blow-up procedure from the Z{sub 6-II} and Z{sub 2} x Z{sub 4} orientifolds.
GUTs on Compact Type IIB Orientifolds
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Blumenhagen, Ralph; /Munich, Max Planck Inst.; Braun, Volker; /Dublin Inst.; Grimm, Thomas W.; /Bonn U.; Weigand, Timo; /SLAC
2008-12-01
We systematically analyze globally consistent SU(5) GUT models on intersecting D7-branes in genuine Calabi-Yau orientifolds with O3- and O7-planes. Beyond the well-known tadpole and K-theory cancellation conditions there exist a number of additional subtle but quite restrictive constraints. For the realization of SU(5) GUTs with gauge symmetry breaking via U(1)Y flux we present two classes of suitable Calabi-Yau manifolds defined via del Pezzo transitions of the elliptically fibred hypersurface P{sub 1,1,1,6,9}[18] and of the Quintic P{sub 1,1,1,1,1}[5], respectively. To define an orientifold projection we classify all involutions on del Pezzo surfaces. We work out the model building prospects of these geometries and present five globally consistent string GUT models in detail, including a 3-generation SU(5) model with no exotics whatsoever. We also realize other phenomenological features such as the 10 10 5{sub H} Yukawa coupling and comment on the possibility of moduli stabilization, where we find an entire new set of so-called swiss-cheese type Calabi-Yau manifolds. It is expected that both the general constrained structure and the concrete models lift to F-theory vacua on compact Calabi-Yau fourfolds.
On the quantum stability of IIB orbifolds and orientifolds with Scherk-Schwarz SUSY breaking
Borunda, M; Trapletti, M
2003-01-01
We study the quantum stability of Type IIB orbifold and orientifold string models in various dimensions, including Melvin backgrounds, where supersymmetry (SUSY) is broken {\\it \\`a la} Scherk-Schwarz (SS) by twisting periodicity conditions along a circle of radius R. In particular, we compute the R-dependence of the one-loop induced vacuum energy density $\\rho(R)$, or cosmological constant. For SS twists different from Z2 we always find, for both orbifolds and orientifolds, a monotonic $\\rho(R)<0$, eventually driving the system to a tachyonic instability. For Z2 twists, orientifold models can have a different behavior, leading either to a runaway decompactification limit or to a negative minimum at a finite value R_0. The last possibility is obtained for a 4D chiral orientifold model where a more accurate but yet preliminary analysis seems to indicate that $R_0\\to \\infty$ or towards the tachyonic instability, as the dependence on the other geometric moduli is included.
On four-derivative terms in IIB Calabi-Yau orientifold reductions
Weissenbacher, Matthias
2016-01-01
We perform a Kaluza-Klein reduction of IIB supergravity including purely gravitational $\\alpha '^3$-corrections on a Calabi-Yau threefold, and perform the orientifold projection accounting for the presence of $O3/O7$-planes. We consider infinitesimal K\\"{a}hler deformations of the Calabi-Yau background and derive the complete set of four-derivative couplings quadratic in these fluctuations coupled to gravity. In particular, we find four-derivative couplings of the K\\"{a}hler moduli fields in the four-dimensional effective supergravity theory, which are referred to as friction couplings in the context of inflation.
Applications of the D-instanton calculus in type IIB orientifold compactifications
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Moster, Sebastian
2010-06-22
In this thesis string compactifications are studied in the formalism of the large-volume type IIB string theory. This class of compactifications possesses an in various regards phenomenologically interesting effective low-energy field theory. Theme of this thesis is the further development of these models motivated by recent knowledges in the D-brane instanton calculus of the string theory. After a short, general introduction in the string theory and especially in type IIB orbifolds and their consistency conditions the large-volume models are extensively presented and the hitherto knowledges on their phenomenology - like scale hierarchies, gauge couplings, supersymmetry breaking, and cosmological questions - discussed. An essential part in the construction of the large-volume models is the stabilizing of moduli fields by means of nonperturbative contribution to the superpotential in the effective low-energy field theory, which are caused by D-brane instantons or gaugino condensates. With recent knowledges in the D-brane instanton calculus it is shown that the moduli stabilization with the hitherto applied mechanism is not compatible with the existence of chiral fermions, as they occur in the standard model of elementary particle physics. A modified mechanism is proposed, in which the moduli fields are stabilized by additions of D-terms. Then by so-called ''polyinstanton corrections'' for the gauge-kinetic function a new large-volume scenario is constructed, in which the string scale without fine tuning lies not in an as in these model usual intermediate range of about 10{sup 11} GeV, but at 10{sup 16} GeV. By this this construction becomes interesting also for grand unified theories with SU(5) or SO(10) gauge groups. This is demonstrated on explicit models. Finally supersymmetry breaking is treated in large-volume scenarios. By the new mechanism for the moduli stabilization it is suggested that the supersymmetry breaking is caused by a
On Fluxed Instantons and Moduli Stabilisation in IIB Orientifolds and F-theory
Grimm, Thomas W; Palti, Eran; Weigand, Timo
2011-01-01
We study the superpotential induced by Euclidean D3-brane instantons carrying instanton flux, with special emphasis on its significance for the stabilisation of Kahler moduli and Neveu-Schwarz axions in Type IIB orientifolds. Quite generally, once a chiral observable sector is included in the compactification, arising on intersecting D7-branes with world-volume flux, resulting charged instanton zero modes prevent a class of instantons from participating in moduli stabilisation. We show that instanton flux on Euclidean D3-branes can remove these extra zero modes and helps in reinstating full moduli stabilisation within a geometric regime. We comment also on the F-theoretic description of this effect of alleviating the general tension between moduli stabilisation and chirality. In addition we propose an alternative solution to this problem based on dressing the instantons with charged matter fields which is unique to F-theory and cannot be realised in the weak coupling limit.
Franco, Sebastian; Krefl, Daniel; Park Jaemo; Uranga, Angel M; Végh, David
2007-01-01
We introduce new techniques based on brane tilings to investigate D3-branes probing orientifolds of toric Calabi-Yau singularities. With these new tools, one can write down many orientifold models and derive the resulting low-energy gauge theories living on the D-branes. Using the set of ideas in this paper one recovers essentially all orientifolded theories known so far. Furthermore, new orientifolds of non-orbifold toric singularities are obtained. The possible applications of the tools presented in this paper are diverse. One particular application is the construction of models which feature dynamical supersymmetry breaking as well as the computation of D-instanton induced superpotential terms.
Burgess, C P; Quevedo, Fernando; Rabadan, Raul
2004-01-01
We study several different kinds of bound states built from D-branes and orientifolds. These states are to atoms what branonium - the bound state of a brane and its anti-brane - is to positronium, inasmuch as they typically involve a light brane bound to a much heavier object with conserved charges which forbid the system's decay. We find the fully relativistic motion of a probe Dp'-brane in the presence of source Dp-branes is integrable by quadratures. Keplerian conic sections are obtained for special choices for p and p' and the systems are shown to be equivalent to nonrelativistic systems. Their quantum behaviour is also equivalent to the corresponding non-relativistic limit. In particular the p=6, p'=0 case is equivalent to a non-relativistic dyon in a magnetic monopole background, with the trajectories in the surface of a cone. We also show that the motion of the probe branes about D6-branes in IIA theory is equivalent to the motion of the corresponding probes in the uplift to M-theory in 11 dimensions, ...
Buchel, Alexander Sergeevich
. In the third part of this thesis we discuss orientifolds of Type IIB strings with quantized B-flux. First, we consider anomaly cancelations in Type IIB orientifolds on T4/ZN , N = 2, 4, with quantized NS-NS sector background B-flux. We identify the twisted sector R-R scalars and tensor multiplets with Green-Schwarz interactions responsible for this cancelation. We present an explicit construction of the models and argue that consistence with 2b/2 multiplicity of 59-sector states requires a modification of the relation between the 1-loop channel and a tree channel modulus for the 59-cylinder amplitudes. We then extend analysis to the four dimensional Type IIB orientifolds on T6/Z6 with NS-NS sector background B-flux. We provide an explicit construction of these four dimensional vacua and show that all gauge anomalies cancel. (Abstract shortened by UMI.)
Can we live on a D-brane? -- Effective theory on a self-gravitating D-brane --
Shiromizu, T; Onda, S; Torii, T; Torii, Takashi
2003-01-01
We consider a D-brane coupled with gravity in type IIB supergravity on S^5 and derive the effective theory on the D-brane in two different ways, that is, holographic and geometrical projection methods. We find that the effective equations on the brane obtained by these methods coincide. The theory on the D-brane described by the Born-Infeld action is not like Einstein-Maxwell theory in the lower order of the gradient expansion, i.e., the Maxwell field does not appear in the theory. Thus the careful analysis and statement for cosmology on self-gravitating D-brane should be demanded in realistic models.
Discrete flavor symmetries in D-brane models
Marchesano, Fernando; Vázquez-Mercado, Liliana
2013-01-01
We study the presence of discrete flavor symmetries in D-brane models of particle physics. By analyzing the compact extra dimensions of these models one can determine when such symmetries exist both in the context of intersecting and magnetized D-brane constructions. Our approach allows to distinguish between approximate and exact discrete symmetries, and it can be applied to compactification manifolds with continuous isometries or to manifolds that only contain discrete isometries, like Calabi-Yau three-folds. We analyze in detail the class of rigid D-branes models based on a Z_2 x Z'_2 toroidal orientifold, for which the flavor symmetry group is either the dihedral group D_4 or tensor products of it. We construct explicit Pati-Salam examples in which families transform in non-Abelian representations of the flavor symmetry group, constraining Yukawa couplings beyond the effect of massive U(1) D-brane symmetries.
Bachlechner, Thomas C
2013-01-01
We study the dynamics of ultrarelativistic D-branes. The dominant phenomenon is bremsstrahlung: mild acceleration induced by closed string interactions triggers extremely rapid energy loss through radiation of massless closed strings. After characterizing bremsstrahlung from a general k-dimensional extended object in a D-dimensional spacetime, we incorporate effects specific to D-branes, including velocity-dependent forces and open string pair creation. We then show that dissipation due to bremsstrahlung can substantially alter the dynamics in DBI inflation.
Bachlechner, Thomas C.; McAllister, Liam
2013-10-01
We study the dynamics of ultrarelativistic D-branes. The dominant phenomenon is bremsstrahlung: mild acceleration induced by closed string interactions triggers extremely rapid energy loss through radiation of massless closed strings. After characterizing bremsstrahlung from a general k-dimensional extended object in a D-dimensional spacetime, we incorporate effects specific to D-branes, including velocity-dependent forces and open string pair creation. We then show that dissipation due to bremsstrahlung can substantially alter the dynamics in DBI inflation.
Anomalies and inflow on D-branes and O-planes
Scrucca, Claudio A; Scrucca, Claudio A.; Serone, Marco
1999-01-01
We derive the general form of the anomaly for chiral spinors and self-dual antisymmetric tensors living on D-brane and O-plane interesections, using both path-integral and index theorem methods. We then show that the anomalous couplings to RR forms of D-branes and O-planes in a general background are precisely those required to cancel these anomalies through the inflow mechanism. This allows, for instance, for local anomaly cancellation in generic orientifold models, the relevant Green-Schwarz term being given by the sum of the anomalous couplings of all the D-branes and O-planes in the model.
Carey, A L; Murray, M K; Carey, Alan L.; Johnson, Stuart; Murray, Michael K.
2002-01-01
This paper shows how to construct anomaly free world sheet actions in string theory with $D$-branes. Our method is to use Deligne cohomology and bundle gerbe theory to define geometric objects which are naturally associated to $D$-branes and connections on them. The holonomy of these connections can be used to cancel global anomalies in the world sheet action.
Aspects of string theory compactifications. D-brane statistics and generalised geometry
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Gmeiner, F.
2006-05-26
In this thesis we investigate two different aspects of string theory compactifications. The first part deals with the issue of the huge amount of possible string vacua, known as the landscape. Concretely we investigate a specific well defined subset of type II orientifold compactifications. We develop the necessary tools to construct a very large set of consistent models and investigate their gauge sector on a statistical basis. In particular we analyse the frequency distributions of gauge groups and the possible amount of chiral matter for compactifications to six and four dimensions. In the phenomenologically relevant case of four-dimensional compactifications, special attention is paid to solutions with gauge groups that include those of the standard model, as well as Pati-Salam, SU(5) and flipped SU(5) models. Additionally we investigate the frequency distribution of coupling constants and correlations between the observables in the gauge sector. These results are compared with a recent study of Gepner models. Moreover, we elaborate on questions concerning the finiteness of the number of solutions and the computational complexity of the algorithm. In the second part of this thesis we consider a new mathematical framework, called generalised geometry, to describe the six-manifolds used in string theory compactifications. In particular, the formulation of T-duality and mirror symmetry for nonlinear topological sigma models is investigated. Therefore we provide a reformulation and extension of the known topological A- and B-models to the generalised framework. The action of mirror symmetry on topological D-branes in this setup is presented and the transformation of the boundary conditions is analysed. To extend the considerations to D-branes in type II string theory, we introduce the notion of generalised calibrations. We show that the known calibration conditions of supersymmetric branes in type IIA and IIB can be obtained as special cases. Finally we investigate
Orientifolding in N=2 superspace
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Robles-Llana, D.; Saueressig, F.; Vandoren, S. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Utrecht (Netherlands); Rocek, M. [C.N. Yang Institute for Theoretical Physics, Stony Brook University, NY 11794-3840 (United States); Theis, U. [Institute for Theoretical Physics, Friedrich-Schiller-University Jena, 07743 Jena (Germany)
2007-05-15
We discuss orientifold projections on superspace effective actions for hypermultiplets. We present a simple and new mechanism that allows one to find the Kaehler potential and complex structure for the N=1 theory directly in terms of the parent N=2 theory. As an application, we demonstrate our method for Calabi-Yau orientifold compactifications of type IIB superstrings. (Abstract Copyright [2007], Wiley Periodicals, Inc.)
D-brane physics. From weak to strong coupling
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Vieira Lopes, Daniel Ordine
2013-01-10
In this thesis we discuss two aspects of branes relevant to high-energy phenomenology. First, we consider a single D6-brane wrapping a special Lagrangian cycle and the background space compactified in a Calabi-Yau orientifold the conditions needed to obtain a four-dimensional N=1 supersymmetric theory. We calculate the bosonic part of the effective action by performing a Kaluza-Klein reduction of the brane seven-dimensional action, and obtain the N=1 characteristic data. To discuss the moduli, we first fix the moduli from deformations of the background Calabi-Yau and study the D-brane deformation moduli space. We next allow for Calabi-Yau deformations, and show that the moduli space for complex structure deformations is corrected by the fields living on the D6-brane. We also calculate the scalar potential from D- and F-terms generated from brane and background configurations that would break the supersymmetry condition. We then, via Mirror Symmetry, relate the spectrum obtained in our work to the spectrum in Type IIB effective theory with D3- D5- and D7-branes, and we propose a Kaehler potential for the moduli space of brane deformations in Type IIB theories. In the second part of the thesis we discuss effects of brane intersections when the string coupling can become strong, and we work in the framework of F-theory. After reviewing the basics of F-theory constructions and a particular SU(5) model already discussed in the literature, we construct a model which contains a point of E{sub 8} singularity, and curves of E{sub 6} singularity. By explicitly resolving the space, we show that the resolution requires the introduction of higher dimensional fibers, and argue how we can circumvent this problem for the E{sub 6} curve, leading to the expected resolution that generate an E{sub 6} group, while at the E{sub 8} point we cannot make the resolution lead to an expected E{sub 8} structure.
D-brane networks in flux vacua, generalized cycles and calibrations
Evslin, Jarah; Martucci, Luca
2007-07-01
We consider chains of generalized submanifolds, as defined by Gualtieri in the context of generalized complex geometry, and define a boundary operator that acts on them. This allows us to define generalized cycles and the corresponding homology theory. Gauge invariance demands that D-brane networks on flux vacua must wrap these generalized cycles, while deformations of generalized cycles inside of a certain homology class describe physical processes such as the dissolution of D-branes in higher-dimensional D-branes and MMS-like instantonic transitions. We introduce calibrations that identify the supersymmetric D-brane networks, which minimize their energy inside of the corresponding homology class of generalized cycles. Such a calibration is explicitly presented for type II Script N = 1 flux compactifications to four dimensions. In particular networks of walls and strings in compactifications on warped Calabi-Yau's are treated, with explicit examples on a toroidal orientifold vacuum and on the Klebanov-Strassler geometry.
D-brane networks in flux vacua, generalized cycles and calibrations
Evslin, J; Evslin, Jarah; Martucci, Luca
2007-01-01
We consider chains of generalized submanifolds, as defined by Gualtieri in the context of generalized complex geometry, and define a boundary operator that acts on them. This allows us to define generalized cycles and the corresponding homology theory. Gauge invariance demands that D-brane networks on flux vacua must wrap these generalized cycles, while deformations of generalized cycles inside of a certain homology class describe physical processes such as the dissolution of D-branes in higher-dimensional D-branes and MMS-like instantonic transitions. We introduce calibrations that identify the supersymmetric D-brane networks, which minimize their energy inside of the corresponding homology class of generalized cycles. Such a calibration is explicitly presented for type II N=1 flux compactifications to four dimensions. In particular networks of walls and strings in compactifications on warped Calabi-Yau's are treated, with explicit examples on a toroidal orientifold vacuum and on the Klebanov-Strassler geome...
Orientifolds of string theory Melvin backgrounds
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Angelantonj, Carlo E-mail: carlo.angelantonj@cern.ch; Dudas, Emilian; Mourad, Jihad
2002-08-19
We study the dynamics of type I strings on Melvin backgrounds, with a single or multiple twisted two-planes. We construct two inequivalent types of orientifold models that correspond to (non-compact) irrational versions of Scherk-Schwarz type breaking of supersymmetry. In the first class of vacua, D-branes and O-planes are no longer localized in space-time but are smeared along the compact Melvin coordinate with a characteristic profile. On the other hand, the second class of orientifolds involves O-planes and D-branes that are both rotated by an angle proportional to the twist. In case of 'multiple Melvin spaces', some amount of supersymmetry is recovered if the planes are twisted appropriately and part of the original O-planes are transmuted into new ones. The corresponding boundary and crosscap states are determined.
The supergravity fields for a D-brane with a travelling wave from string amplitudes
Black, William; Turton, David
2010-01-01
We calculate the supergravity fields sourced by a D-brane with a null travelling wave from disk amplitudes in type IIB string theory compactified on T^4 x S^1. The amplitudes reproduce the non-trivial features of the previously known two-charge supergravity solutions in the D-brane/momentum frame, providing a direct link between the microscopic bound states and their macroscopic descriptions.
The supergravity fields for a D-brane with a travelling wave from string amplitudes
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Black, William, E-mail: w.black@qmul.ac.u [Queen Mary University of London, Centre for Research in String Theory, Department of Physics, Mile End Road, London E1 4NS (United Kingdom); Russo, Rodolfo, E-mail: r.russo@qmul.ac.u [Queen Mary University of London, Centre for Research in String Theory, Department of Physics, Mile End Road, London E1 4NS (United Kingdom); Turton, David, E-mail: d.j.turton@qmul.ac.u [Queen Mary University of London, Centre for Research in String Theory, Department of Physics, Mile End Road, London E1 4NS (United Kingdom)
2010-11-08
We calculate the supergravity fields sourced by a D-brane with a null travelling wave from disk amplitudes in type IIB string theory compactified on T{sup 4}xS{sup 1}. The amplitudes reproduce all the non-trivial features of the previously known two-charge supergravity solutions in the D-brane/momentum duality frame, providing a direct link between the microscopic bound states and their macroscopic descriptions.
D-branes, Supersymmetry Breaking, and Neutrinos
Seo, Jihye
2010-01-01
This thesis studies meta- and exactly stable supersymmetry breaking mechanisms in heterotic and type IIB string theories and constructs an F-theory Grand Unified Theory model for neutrino physics in which neutrino mass is determined by the supersymmetry breaking mechanism. Focussing attention on heterotic string theory compactified on a 4-torus, stability of non-supersymmetric states is studied. A non-supersymmetric state with robust stability is constructed, and its exact stability is proven in a large region of moduli space of T^4 against all the possible decay mechanisms allowed by charge conservation. Using string-string duality, the results are interpreted in terms of Dirichlet-branes in type IIA string theory compactified on an orbifold limit of a K3 surface. In type IIB string theory, metastable and exactly stable non-supersymmetric systems are constructed using D-branes and Calabi-Yau geometry. Branes and anti-branes wrap rigid and separate 2-spheres inside a non-compact Calabi-Yau three-fold: supersy...
Gravitational backreaction of anti-D branes in the warped compactification
Koyama, K; Koyama, Kayoko; Koyama, Kazuya
2005-01-01
We derive a low-energy effective theory for gravity with anti-D branes, which are essential to get de Sitter solutions in the type IIB string warped compactification, by taking account of gravitational backreactions of anti-D branes. In order to see the effects of the self-gravity of anti-D branes, a simplified model is studied where a 5-dimensional anti-de Sitter ({\\it AdS}) spacetime is realized by the bulk cosmological constant and the 5-form flux, and anti-D branes are coupled to the 5-form field by Chern-Simon terms. The {\\it AdS} spacetime is truncated by introducing UV and IR cut-off branes like the Randall-Sundrum model. We derive an effective theory for gravity on the UV brane and reproduce the familiar result that the tensions of the anti-D branes give potentials suppressed by the forth-power of the warp factor at the location of the anti-D branes. However, in this simplified model, the potential energy never inflates the UV brane, although the anti-D-branes are inflating. The UV brane is dominated ...
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Koivisto, Tomi [Institute for Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway); Wills, Danielle [Centre for Particle Theory, Department of Mathematical Sciences, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Zavala, Ivonne, E-mail: t.s.koivisto@astro.uio.no, E-mail: d.e.wills@durham.ac.uk, E-mail: e.i.zavala@rug.nl [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)
2014-06-01
Disformally coupled cosmologies arise from Dirac-Born-Infeld actions in Type II string theories, when matter resides on a moving hidden sector D-brane. Since such matter interacts only very weakly with the standard model particles, this scenario can provide a natural origin for the dark sector of the universe with a clear geometrical interpretation: dark energy is identified with the scalar field associated to the D-brane's position as it moves in the internal space, acting as quintessence, while dark matter is identified with the matter living on the D-brane, which can be modelled by a perfect fluid. The coupling functions are determined by the (warped) extra-dimensional geometry, and are thus constrained by the theory. The resulting cosmologies are studied using both dynamical system analysis and numerics. From the dynamical system point of view, one free parameter controls the cosmological dynamics, given by the ratio of the warp factor and the potential energy scales. The disformal coupling allows for new scaling solutions that can describe accelerating cosmologies alleviating the coincidence problem of dark energy. In addition, this scenario may ameliorate the fine-tuning problem of dark energy, whose small value may be attained dynamically, without requiring the mass of the dark energy field to be unnaturally low.
Particle models from orientifolds at Gepner-orbifold points
Aldazabal, G; Juknevich, J E
2004-01-01
We consider configurations of stacks of orientifold planes and D-branes wrapped on a non trivial internal space of the structure {(Gepner model)^{c=3n} x T^{2(3-n)}}/Z_N, for n=1,2,3. By performing simple moddings by discrete symmetries of Gepner models at orienti fold points, consistent with a Z_N orbifold action, we show that projection on D-brane configurations can be achieved, generically leading to chiral gauge theories. Either supersymmetric or non-supersymmetric (tachyon free) models can be obtained. We illustrate the procedure through some explicit examples.
Hashimoto, Koji
2015-01-01
We show that band spectrum of topological insulators can be identified as the shape of D-branes in string theory. The identification is based on a relation between the Berry connection associated with the band structure and the ADHM/Nahm construction of solitons whose geometric realization is available with D-branes. We also show that chiral and helical edge states are identified as D-branes representing a noncommutative monopole.
Dynamical Generation of Yukawa Couplings in Intersecting D-brane Models
Kitazawa, N
2004-01-01
We propose a scenario to obtain non-trivial Yukawa coupling matrices for the quark-lepton mass generation in supersymmetric intersecting D-brane models in type IIA T^6/Z_2 x Z_2 orientifold. As an example, an explicit model is constructed in which all the four generations of quarks and leptons and two pairs of massless Higgs fields are composite. In this model non-trivial Yukawa interactions are obtained by the interplay between the string-level higher dimensional interactions among "preons" and the dynamics of the confinement of "preons".
D-Brane Recoil Mislays Information
Ellis, Jonathan Richard; Nanopoulos, Dimitri V
1998-01-01
We discuss the scattering of a light closed-string state off a $D$ brane, taking into account quantum recoil effects on the latter, which are described by a pair of logarithmic operators. The light-particle and $D$-brane subsystems may each be described by a world-sheet with an external source due to the interaction between them. This perturbs each subsystem away from criticality, which is compensated by dressing with a Liouville field whose zero mode we interpret as time. The resulting evolution equations for the $D$ brane and the closed string are of Fokker-Planck and modified quantum Liouville type, respectively. The apparent entropy of each subsystem increases as a result of the interaction between them, which we interpret as the loss of information resulting from non-observation of the other entangled subsystem. We speculate on the possible implications of these results for the propagation of closed strings through a dilute gas of virtual $D$ branes.
T-Duality for Orientifolds and Twisted KR-Theory
Doran, Charles; Méndez-Diez, Stefan; Rosenberg, Jonathan
2014-08-01
D-brane charges in orientifold string theories are classified by the KR-theory of Atiyah. However, this is assuming that all O-planes have the same sign. When there are O-planes of different signs, physics demands a "KR-theory with a sign choice" which up until now has not been studied by mathematicians (with the unique exception of Moutuou, who did not have a specific application in mind). We give a definition of this theory and compute it for orientifold theories compactified on S 1 and T 2. We also explain how and why additional "twisting" is implemented. We show that our results satisfy all possible T-duality relationships for orientifold string theories on elliptic curves, which will be studied further in subsequent work.
Ramgoolam, S.; Thorlacius, L.
1996-01-01
States obtained by projecting boundary states, associated with D-branes, to fixed mass-level and momentum generically define non-trivial cohomology classes. For on-shell states the cohomology is the standard one, but when the states are off-shell the relevant cohomology is defined using a BRST operator with ghost zero modes removed. The zero momentum cohomology falls naturally into multiplets of $SO(D-1,1)$. At the massless level, a simple set of D-brane configurations generates the full set ...
Generalized N=1 orientifold compactifications and the Hitchin functionals
Energy Technology Data Exchange (ETDEWEB)
Benmachiche, I. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Grimm, T.W. [Wisconsin Univ., Madison, WI (United States). Dept. of Physics
2006-02-15
The four-dimensional N=1 supergravity theories arising in compactifications of type IIA and type IIB on generalized orientifold backgrounds with background fluxes are discussed. The Kaehler potentials are derived for reductions on SU(3) structure orientifolds and shown to consist of the logarithm of the two Hitchin functionals. These are functions of even and odd forms parameterizing the geometry of the internal manifold, the B-field and the dilaton. The superpotentials induced by background fluxes and the non-Calabi-Yau geometry are determined by a reduction of the type IIA and type IIB fermionic actions on SU(3) and generalized SU(3) x SU(3) manifolds. Mirror spaces of Calabi-Yau orientifolds with electric and part of the magnetic NS-NS fluxes are conjectured to be certain SU(3) x SU(3) structure manifolds. Evidence for this identification is provided by comparing the generalized type IIA and type IIB superpotentials. (orig.)
String Thermodynamics in D-Brane Backgrounds
Abel, S A; Kogan, I I; Rabinovici, Eliezer
1999-01-01
We discuss the thermal properties of string gases propagating in various D-brane backgrounds in the weak-coupling limit, and at temperatures close to the Hagedorn temperature. We determine, in the canonical ensemble, whether the Hagedorn temperature is limiting or non-limiting. This depends on the dimensionality of the D-brane, and the size of the compact dimensions. We find that in many cases the non-limiting behaviour manifest in the canonical ensemble is modified to a limiting behaviour in the microcanonical ensemble and show that, when there are different systems in thermal contact, the energy flows into open strings on the `limiting' D-branes of largest dimensionality. Such energy densities may eventually exceed the D-brane intrinsic tension. We discuss possible implications of this for the survival of Dp-branes with large values of p in an early cosmological Hagedorn regime. We also discuss the general phase diagram of the interacting theory, as implied by the holographic and black-hole/string correspon...
Equivalence of D-brane categories
Quintero Velez, A.
2009-01-01
In this thesis certain aspects of D-branes and their role in a deeper understanding of gauged linear sigma models and quiver gauge theories are investigated, including the relevant categories in the mathematical setup. Our applications include the development of a McKay correspondence for Landau-Gin
Energy Technology Data Exchange (ETDEWEB)
McGreevy, John Austen; /Stanford U., Phys. Dept.
2005-07-06
This thesis is a study of D-branes in string compactifications. In this context, D-branes are relevant as an important component of the nonperturbative spectrum, as an incisive probe of these backgrounds, and as a natural stringy tool for localizing gauge interactions. In the first part of the thesis, we discuss half-BPS D-branes in compactifications of type II string theory on Calabi-Yau threefolds. The results we describe for these objects are pertinent both in their role as stringy brane-worlds, and in their role as solitonic objects. In particular, we determine couplings of these branes to the moduli determining the closed-string geometry, both perturbatively and non-perturbatively in the worldsheet expansion. We provide a local model for transitions in moduli space where the BPS spectrum jumps, and discuss the extension of mirror symmetry between Calabi-Yau manifolds to the case when D-branes are present. The next section is an interlude which provides some applications of D-branes to other curved backgrounds of string theory. In particular, we discuss a surprising phenomenon in which fundamental strings moving through background Ramond-Ramond fields dissolve into large spherical D3-branes. This mechanism is used to explain a previously-mysterious fact discovered via the AdS-CFT correspondence. Next, we make a connection between type IIA string vacua of the type discussed in the first section and M-theory compactifications on manifolds of G{sub 2} holonomy. Finally we discuss constructions of string vacua which do not have large radius limits. In the final part of the thesis, we develop techniques for studying the worldsheets of open strings ending on the curved D-branes studied in the first section. More precisely, we formulate a large class of massive two-dimensional gauge theories coupled to boundary matter, which flow in the infrared to the relevant boundary conformal field theories. Along with many other applications, these techniques are used to describe
Indian Academy of Sciences (India)
David Bailin
2003-02-01
I brieﬂy outline previous work on getting the (supersymmetric) standard model from string theory, and then describe two ecent attempts using D-branes. The ﬁrst uses D3- and D7- branes and gives a supersymmetric standard model with extra vector-like matter and an intermediate uniﬁcation scale. The second uses intersecting D4-branes and yields a non-supersymmetric spectrum with TeV-scale uniﬁcation.
D-Brane Inflation on Conifolds
Halyo, E
2004-01-01
We describe a model of D--brane inflation on fractional D3 branes transverse to a resolved and deformed conifold. The resolution and the deformation are both necessary for inflation. The fractional branes slowly approach each other along the $S^3$ and separate along the $S^2$ in the base of the conifold. We show that on the brane this corresponds to hybrid inflation. We describe the model also in terms of intersecting branes.
Gravitational Couplings on D-brane Revisited
Ghodsi, Ahmad
2016-01-01
Gravitational couplings in bulk space-time include those terms which are fixed by scattering amplitude of strings and ambiguous terms that are coming from the field redefinitions. These field redefinitions can be fixed in the bulk by ghost-free condition. In this paper we have revised the effective gravitational couplings on D-branes by including the field redefinitions. We find the gravitational effective action up to $\\alpha'^2$-order.
Holographic backgrounds from D-brane probes
Moskovic, Micha
2014-01-01
This thesis focuses on the derivation of holographic backgrounds from the field theory side, without using any supergravity equations of motion. Instead, we rely on the addition of probe D-branes to the stack of D-branes generating the background. From the field theory description of the probe branes, one can compute an effective action for the probes (in a suitable low-energy/near-horizon limit) by integrating out the background branes. Comparing this action with the generic probe D-brane action then allows to determine the holographic background dual to the considered field theory vacuum. In the first part, the required pre-requisites of field and string theory are recalled and this strategy to derive holographic backgrounds is explained in more detail on the basic case of D3-branes in flat space probed by a small number of D-instantons. The second part contains our original results, which have already appeared in arXiv:1301.3738, arXiv:1301.7062 and arXiv:1312.0621. We first derive the duals to three conti...
BPS domain walls from backreacted orientifolds
Blåbäck, Johan; Van Riet, Thomas; Vercnocke, Bert
2013-01-01
Compactifications with D-brane and orientifold sources lead to standard gauged supergravity theories if the sources are smeared over the internal directions. It is therefore of interest to find how the solutions described by the gauged supergravity are altered by properly localising the sources. In this paper we analyse this for BPS domain wall solutions in the seven-dimensional gauged supergravity obtained from an O6 toroidal orientifold compactification in massive IIA supergravity. This is one of the simplest no-scale supergravities that can be constructed and analysed in full detail. We find and discuss the BPS domain walls both when the O6 planes are smeared and localised. When the O6 planes are localised the domain wall solutions live in a warped compactification. In order to get explicit expressions we also consider the non-compact versions of the solutions for which the O6 planes have been traded for D6 branes. Through T-duality we obtain partially localised solutions for compactifications to four dime...
Noncommutative Yang-Mills in IIB Matrix Model
Aoki, H; Iso, S; Kawai, H; Kitazawa, Y; Tada, T
2000-01-01
We show that twisted reduced models can be interpreted as noncommutative Yang-Mills theory. Based upon this correspondence, we obtain noncommutative Yang-Mills theory with D-brane backgrounds in IIB matrix model. We propose that IIB matrix model with D-brane backgrounds serve as a concrete definition of noncommutative Yang-Mills. We investigate D-instanton solutions as local excitations on D3-branes. When instantons overlap, their interaction can be well described in gauge theory and AdS/CFT correspondence. We show that IIB matrix model gives us the consistent potential with IIB supergravity when they are well separated.
750 GeV diphoton excesses in a realistic D-brane model
Li, Tianjun; Maxin, James A.; Mayes, Van E.; Nanopoulos, Dimitri V.
2016-07-01
We study the diphoton excesses near 750 GeV recently reported by the ATLAS and CMS collaborations within the context of a phenomenologically interesting intersecting/magnetized D-brane model on a toroidal orientifold. It is shown that the model contains a Standard Model singlet scalar as well as vector-like quarks and leptons. In addition, it is shown that the singlet scalar has Yukawa couplings with vector-like quarks and leptons such that it may be produced in proton-proton collisions via gluon fusion as well as decay to diphotons through loops involving the vector-like quarks. Moreover, the required vector-like quarks and leptons may appear in complete S U (5 ) multiplets so that gauge coupling unification may be maintained. Finally, it is shown that the diphoton signal may be accommodated within the model.
The $750$ GeV Diphoton Excesses in a Realistic D-brane Model
Li, Tianjun; Mayes, Van E; Nanopoulos, Dimitri V
2016-01-01
We study the diphoton excesses near $750$ GeV recently reported by the ATLAS and CMS collaborations within the context of a phenomenologically interesting intersecting/magnetized D-brane model on a toroidal orientifold. It is shown that the model contains a SM singlet scalar as well as vector-like quarks and leptons. In addition, it is shown that the singlet scalar has Yukawa couplings with vector-like quarks and leptons such that it may be produced in proton-proton collisions via gluon fusion as well as decay to diphotons through loops involving the vector-like quarks. Moreover, the required vector-like quarks and leptons may appear in complete $SU(5)$ multiplets so that gauge coupling unification may be maintained. Finally, it is shown that the diphoton signal may be explained within the model.
Dijkgraaf, R.
We study of chiral fermions on a quantum curve by embedding them instring theory as an intersecting D-brane configuration together with a B-field. Mathematically, this system is described by a holonomic D-module. Here we focus on spectral curves, which play a prominant role in the theory of (quantum) integrable hierarchies. We show how to associate a quantum state to the system, and subsequently how to compute quantum invariants. The material of this paper is treated at greater length in the paper [R.~Dijkgraaf, L.~Hollands and P.~Sulkowski, arXiv:0810.4157] that also contains many examples.
Energy Technology Data Exchange (ETDEWEB)
Horowitz, Gary; /UC, Santa Barbara; Lawrence, Albion; /Brandeis U. /Santa Barbara, KITP; Silverstein, Eva; /SLAC /Stanford U., Phys. Dept. /Santa Barbara, KITP
2010-08-26
We study a simple model of a black hole in AdS and obtain a holographic description of the region inside the horizon. A key role is played by the dynamics of the scalar fields in the dual gauge theory. This leads to a proposal for a dual description of D-branes falling through the horizon of any AdS black hole. The proposal uses a field-dependent time reparameterization in the field theory. We relate this reparametrization to various gauge invariances of the theory. Finally, we speculate on information loss and the black hole singularity in this context.
String Fluid from Unstable D-branes
Gibbons, G W; Yi, P; Gibbons, Gary; Hori, Kentaro; Yi, Piljin
2001-01-01
We consider Sen's effective action for unstable D-branes, and study its classical dynamics exactly. In the true vacuum, the Hamiltonian dynamics remains well-defined despite a vanishing action, and is that of massive relativistic string fluid of freely moving electric flux lines. The energy(tension) density equals the flux density in the local co-moving frame. Furthermore, a finite dual Lagrangian exists and is related to the Nielsen-Olesen field theory of ``dual'' strings, supplemented by a crucial constraint. We conclude with discussion on the endpoint of tachyon condensation.
D-brane anti-D-brane system in string theory
Hyakutake, Y
2003-01-01
In this paper, we review a system of D-brane and anti-D-brane in type II superstring theories. [A. Sen, hep-th/9904207 and references there in; Y.Hyakutake, Master-Th., Doctor-Th. (in Japanese)] This system is unstable an tachyonic modes, which have negative mass squared, appear from open strings between D-brane and anti-D-brane. The effective field theory on the world-volume is described by U(1) x U(1) gauge theory with a complex tachyon field. Since the mass squared of the techyon field is negative, a tachyon potential would be like a wine bottle. In order to make the system stable, the tachyon rolls down the potential and gets some vacuum expectation value. This is called the tachyon condensation mechanism. During this mechanism, Dp-brane and anti-Dp-brane annihilate completely, if we admit Sen's conjecture. The suspicions between tachyon condensation and Hawking radiation are also discussed. (author)
Non-BPS D-Branes in Light-Cone Green-Schwarz Formalism
Mukhopadhyay, P
2005-01-01
Non-BPS D-branes are difficult to describe in a manifestly supersymmetric formalism. For definiteness we concentrate on type IIB string theory in flat background in light-cone Green-Schwarz formalism. We study both the boundary state and the boundary conformal field theory descriptions of these D-branes and go through various consistency checks. We analyze Sen's original construction of non-BPS D-branes given in terms of an orbifold boundary conformal field theory. We also directly study the relevant world-sheet theory by deriving the open string boundary condition from the covariant boundary state. Both these methods give the same open string spectrum which is consistent with the boundary state, as required by the world-sheet duality. The boundary condition found in the second method is given in terms of bi-local fields that are quadratic in Green-Schwarz fermions. We design a special ``doubling trick'' suitable to handle such boundary conditions and prescribe rules for computing all possible correlation fun...
D-brane Instantons in Type II String Theory
Blumenhagen, Ralph; Kachru, Shamit; Weigand, Timo
2009-01-01
We review recent progress in determining the effects of D-brane instantons in N=1 supersymmetric compactifications of Type II string theory to four dimensions. We describe the abstract D-brane instanton calculus for holomorphic couplings such as the superpotential, the gauge kinetic function and higher fermionic F-terms. This includes a discussion of multi-instanton effects and the implications of background fluxes for the instanton sector. Our presentation also highlights, but is not restricted to the computation of D-brane instanton effects in quiver gauge theories on D-branes at singularities. We then summarize the concrete consequences of stringy D-brane instantons for the construction of semi-realistic models of particle physics or SUSY-breaking in compact and non-compact geometries.
D-brane Instantons in Type II String Theory
Energy Technology Data Exchange (ETDEWEB)
Blumenhagen, Ralph; /Munich, Max Planck Inst.; Cvetic, Mirjam; /Pennsylvania U.; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC; Weigand, Timo; /SLAC
2009-06-19
We review recent progress in determining the effects of D-brane instantons in N=1 supersymmetric compactifications of Type II string theory to four dimensions. We describe the abstract D-brane instanton calculus for holomorphic couplings such as the superpotential, the gauge kinetic function and higher fermionic F-terms. This includes a discussion of multi-instanton effects and the implications of background fluxes for the instanton sector. Our presentation also highlights, but is not restricted to the computation of D-brane instanton effects in quiver gauge theories on D-branes at singularities. We then summarize the concrete consequences of stringy D-brane instantons for the construction of semi-realistic models of particle physics or SUSY-breaking in compact and non-compact geometries.
D-brane Instantons in Type II String Theory
Energy Technology Data Exchange (ETDEWEB)
Blumenhagen, Ralph; /Munich, Max Planck Inst.; Cvetic, Mirjam; /Pennsylvania U.; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC; Weigand, Timo; /SLAC
2009-06-19
We review recent progress in determining the effects of D-brane instantons in N=1 supersymmetric compactifications of Type II string theory to four dimensions. We describe the abstract D-brane instanton calculus for holomorphic couplings such as the superpotential, the gauge kinetic function and higher fermionic F-terms. This includes a discussion of multi-instanton effects and the implications of background fluxes for the instanton sector. Our presentation also highlights, but is not restricted to the computation of D-brane instanton effects in quiver gauge theories on D-branes at singularities. We then summarize the concrete consequences of stringy D-brane instantons for the construction of semi-realistic models of particle physics or SUSY-breaking in compact and non-compact geometries.
Noncommutative Dirac-Born-Infeld Action for D-brane
Lee, T
2000-01-01
We derive the noncommutative Dirac-Born-Infeld action for the $D$-brane, which governs dynamics of $D$-brane with a NS-NS $B$-field in the low energy regime. Depending on some details of the path integral prescriptions, both ordinary Dirac-Born-Infeld action and noncommutative one can be obtained by evaluating the same Polyakov string path integral for the open string ending on the $D$-brane. Thus, it establishes the equivalence of the noncommutative Dirac-Born-Infeld action and the ordinary one.
New dualities from orientifold transitions Part II: string theory
García-Etxebarria, Iñaki; Heidenreich, Ben; Wrase, Timm
2013-10-01
We present a string theoretical description, given in terms of branes and orientifolds wrapping vanishing cycles, of the dual pairs of gauge theories analyzed in [1]. Based on the resulting construction we argue that the duality that we observe in field theory is inherited from S-duality of type IIB string theory. We analyze in detail the complex cone over the zeroth del Pezzo surface and discuss an infinite family of orbifolds of flat space. For the del Pezzo case we describe the system in terms of large volume objects, and show that in this language the duality can be understood from the strongly coupled behavior of the O7+ plane, which we analyze using simple F-theory considerations. For all cases we also give a different argument based on the existence of appropriate torsional components of the 3-form flux lattice. Along the way we clarify some aspects of the description of orientifolds in the derived category of coherent sheaves, and in particular we discuss the important role played by exotic orientifolds — ordinary orientifolds composed with auto-equivalences of the category — when describing orientifolds of ordinary quiver gauge theories.
D-branes and the Standard Model
Antoniadis, Ignatios; Rizos, J; Tomaras, T N
2003-01-01
We perform a systematic study of the Standard Model embedding in a D-brane configuration of type I string theory at the TeV scale. We end up with an attractive model and we study several phenomenological questions, such as gauge coupling unification, proton stability, fermion masses and neutrino oscillations. At the string scale, the gauge group is U(3)_color x U(2)_weak x U(1)_1 x U(1)_bulk. The corresponding gauge bosons are localized on three collections of branes; two of them describe the strong and weak interactions, while the last abelian factor lives on a brane which is extended in two large extra dimensions with a size of afew microns. The hypercharge is a linear combination of the first three U(1)s. All remaining U(1)s get masses at the TeV scale due to anomalies, leaving the baryon and lepton numbers as (perturbatively) unbroken global symmetries at low energies. The conservation of baryon number assures proton stability, while lepton number symmetry guarantees light neutrino masses that involve a r...
Maldacena, J M; Maldacena, Juan M; Susskind, Leonard
1996-01-01
The application of D-brane methods to large black holes whose Schwarzschild radius is larger than the compactification scale is problematic. Callan and Maldacena have suggested that despite apparent problems of strong interactions when the number of branes becomes large, the open string degrees of freedom may remain very dilute due to the growth of the horizon area which they claim grows more rapidly than the average number of open strings. Such a picture of a dilute weakly coupled string system conflicts with the picture of a dense string-soup that saturates the bound of one string per planck area. A more careful analysis shows that Callan and Maldacena were not fully consistent in their estimates. In the form that their model was studied it can not be used to extrapolate to large mass without being in conflict with the Hawking Bekenstein entropy formula. A somewhat modified model can reproduce the correct entropy formula. In this ``improved model" the number of string bits on the horizon scales like the ent...
Differential K-characters and D-branes
Ruffino, Fabio Ferrari
2016-01-01
Starting from the definition of Cheeger-Simons K-character, we show how to describe D-brane world-volumes, the Wess-Zumino action and topological D-brane charges within the K-theoretical framework in type II superstring theory. We stress in particular how each feature of the old cohomological classification can be reproduced using the K-theoretical language.
Rotation of D-brane and Non-commutative Geometry
Wang, P; Wang, Pei; Yue, Ruihong
1999-01-01
Our motivation is to find the relationship between the commutator of coordinates and uncertainty relation involving only the coordinates. The boundary condition with constant background field is connected with the rotation of D-brane at general angle. And the mode expansions of D-brane we found is more reasonable than those appeared in literature. The partition functions and scattering amplitudes are also discussed.
Flavor structure in D-brane models: Majorana neutrino masses
Hamada, Yuta; Kobayashi, Tatsuo; Uemura, Shohei
2014-05-01
We study the flavor structure in intersecting D-brane models. We study anomalies of the discrete flavor symmetries. We analyze the Majorana neutrino masses, which can be generated by D-brane instanton effects. It is found that a certain pattern of mass matrix is obtained and the cyclic permutation symmetry remains unbroken. As a result, trimaximal mixing matrix can be realized if Dirac neutrino mass and charged lepton mass matrices are diagonal.
Flavor structure in D-brane models: Majorana neutrino masses
Hamada, Yuta; Uemura, Shohei
2014-01-01
We study the flavor structure in intersecting D-brane models. We study anomalies of the discrete flavor symmetries. We analyze the Majorana neutrino masses, which can be generated by D-brane instanton effects. It is found that a certain pattern of mass matrix is obtained and the cyclic permutation symmetry remains unbroken. As a result, trimaximal mixing matrix can be realized if Dirac neutrino mass and charged lepton mass matrices are diagonal.
Some Navigation Rules for D-Brane Monodromy
Aspinwall, Paul S
2001-01-01
We explore some aspects of monodromies of D-branes in the Kahler moduli space of Calabi-Yau compactifications. Here a D-brane is viewed as an object of the derived category of coherent sheaves. We compute all the interesting monodromies in some nontrivial examples and link our work to recent results and conjectures concerning helices and mutations. We note some particular properties of the 0-brane.
D-branes and the Standard Model
Energy Technology Data Exchange (ETDEWEB)
Antoniadis, I.; Kiritsis, E.; Rizos, J. E-mail: irizos@cc.uoi.gr; Tomaras, T.N
2003-06-09
We perform a systematic study of the Standard Model embedding in a D-brane configuration of type I string theory at the TeV scale. We end up with an attractive model and we study several phenomenological questions, such as gauge coupling unification, proton stability, fermion masses and neutrino oscillations. At the string scale, the gauge group is U(3){sub color}xU(2){sub weak}xU(1){sub 1}xU(1){sub bulk}. The corresponding gauge bosons are localized on three collections of branes; two of them describe the strong and weak interactions, while the last Abelian factor lives on a brane which is extended in two large extra dimensions with a size of a few microns. The hypercharge is a linear combination of the first three U(1)'s. All remaining U(1)'s get masses at the TeV scale due to anomalies, leaving the baryon and lepton numbers as (perturbatively) unbroken global symmetries at low energies. The conservation of baryon number assures proton stability, while lepton number symmetry guarantees light neutrino masses that involve a right-handed neutrino in the bulk. The model predicts the value of the weak angle which is compatible with the experiment when the string scale is in the TeV region. It also contains two Higgs doublets that provide tree-level masses to all fermions of the heaviest generation, with calculable Yukawa couplings; one obtains a naturally heavy top and the correct ratio m{sub b}/m{sub {tau}}. We also study neutrino masses and mixings in relation to recent solar and atmospheric neutrino data.
A Solution to the Doublet-Triplet Splitting Problem in the Type IIB Supergravity
Watari, T
2002-01-01
The doublet--triplet mass splitting problem is one of the most serious problems in supersymmetric grand unified theories (GUTs). A class of models based on a product gauge group, such as the SU(5)_{GUT} times U(3)_H or the SU(5)_{GUT} times U(2)_H, realize naturally the desired mass splitting that is protected by an unbroken R symmetry. It has been pointed out that various features in the models suggest that these product-group unification models are embedded in a supersymmetric brane world. We show an explicit construction of those models in the supersymmetric brane world based on the Type IIB supergravity in ten dimensions. We consider T^6/(Z_{12} times Z_2) orientifold for the compactified six extra dimensions. We find that all of the particles needed for the GUT-symmetry-breaking sector are obtained from the D-brane fluctuations. The three families of quarks and leptons are introduced at an orbifold singularity, although their origin remains unexplained. This paper includes extensive discussion on anomaly...
Spiked Instantons from Intersecting D-branes
Nekrasov, Nikita
2016-01-01
The moduli space of spiked instantons that arises in the context of the BPS/CFT correspondence is realised as the moduli space of classical vacua, i.e. low-energy open string field configurations, of a certain stack of intersecting D1-branes and D5-branes in Type IIB string theory. The presence of a constant B-field induces an interesting dynamics involving the tachyon condensation.
Spiked instantons from intersecting D-branes
Directory of Open Access Journals (Sweden)
Nikita Nekrasov
2017-01-01
Full Text Available The moduli space of spiked instantons that arises in the context of the BPS/CFT correspondence [22] is realised as the moduli space of classical vacua, i.e. low-energy open string field configurations, of a certain stack of intersecting D1-branes and D5-branes in Type IIB string theory. The presence of a constant B-field induces an interesting dynamics involving the tachyon condensation.
Spiked instantons from intersecting D-branes
Nekrasov, Nikita; Prabhakar, Naveen S.
2017-01-01
The moduli space of spiked instantons that arises in the context of the BPS/CFT correspondence [22] is realised as the moduli space of classical vacua, i.e. low-energy open string field configurations, of a certain stack of intersecting D1-branes and D5-branes in Type IIB string theory. The presence of a constant B-field induces an interesting dynamics involving the tachyon condensation.
Issues on Orientifolds On the brane construction of gauge theories with SO(2n) global symmetry
Hanany, A; Hanany, Amihay; Zaffaroni, Alberto
1999-01-01
We discuss issues related to orientifolds and the brane realization for gauge theories with orthogonal and symplectic groups. We specifically discuss the case of theories with (hidden) global SO(2n) symmetry, from three to six dimensions. We analyze mirror symmetry for three dimensional N=4 gauge theories, Brane Box Models and six-dimensional gauge theories. We also discuss the issue of T-duality for D_n space-time singularities. Stuck D branes on ON^0 planes play an interesting role.
Topological Insulators and Superconductors from D-branes
Ryu, Shinsei
2010-01-01
Realization of topological insulators (TIs) and superconductors (TSCs), such as the quantum spin Hall effect and the Z_2 topological insulator, in terms of D-branes in string theory is proposed. We establish a one-to-one correspondence between the K-theory classification of TIs/TSCs and D-brane charges. The string theory realization of TIs and TSCs comes naturally with gauge interactions, and the Wess-Zumino term of the D-branes gives rise to a gauge field theory of topological nature. This sheds light on TIs and TSCs beyond non-interacting systems, and the underlying topological field theory description thereof. In particular, our string theory realization includes the honeycomb lattice Kitaev model in two spatial dimensions, and its higher-dimensional extensions.
D-branes in String theory Melvin backgrounds
Dudas, E A
2002-01-01
We determine the consistent D-brane configurations in type II nonsupersymmetric Melvin Background. The D-branes are analysed from three complementary points of view: the effective Born-Infeld action, the open string partition function and the boundary state approach. We show the agreement of the results obtained by the three different approaches. Among the surprising features is the existence of supersymmetric branes, some of them having a quasi-periodic direction. We also discuss the generalisation to backgrounds with several magnetic fields, some of them preserving in the closed and the open spectra some amount of supersymmetry. The case of rational magnetic flux, equivalent to freely-acting noncompact orbifolds, is also studied. It allows more possibilities of consistent D-brane configurations.
On the microcanonical description of D-brane thermodynamics
Meana, M L; Meana, Marco Laucelli; Peñalba, Jesús Puente
1999-01-01
We study the microcanonical description of string gases in the presence of D-branes. We obtain exact expressions for the single string density of states and draw the regions in phase space where asymptotic approximations are valid. We are able to describe the whole range of energies including the SYM phase of the D-branes and we remark the importance of the infrared cut-off used in the high energy approximations. With the complete expression we can obtain the density of states of the multiple string gas and study its thermal properties, showing that the Hagedorn temperature is maximum for every system and there is never a phase transition whenever there is thermal contact among the strings attached to different D-branes.
Israel, D
2005-01-01
We study the exact construction of D-branes in Lorentzian AdS(3). We start by defining a family of conformal field theories that gives a natural Euclidean version of the SL(2,R) CFT and does not correspond to H(3)+, the analytic continuation of AdS(3). We argue that one can recuperate the exact CFT results of Lorentzian AdS(3), upon an analytic continuation in the moduli space of these conformal field theories. Then we construct exact boundary states for various symmetric and symmetry-breaking D-branes in AdS(3).
Axion stabilization in type IIB flux compactifications
Hristov, K.
2009-01-01
A scenario for stabilization of axionic moduli fields in the context of type IIB Calabi-Yau flux compactifications is discussed in detail. We consider the case of a Calabi-Yau orientifold with h1,1−≠0 which allows for the presence of B2 and C2-moduli. In an attempt to generalize the KKLT and the Lar
Axion stabilization in type IIB flux compactifications
Hristov, K.
2009-01-01
A scenario for stabilization of axionic moduli fields in the context of type IIB Calabi-Yau flux compactifications is discussed in detail. We consider the case of a Calabi-Yau orientifold with h1,1−≠0 which allows for the presence of B2 and C2-moduli. In an attempt to generalize the KKLT and the Lar
Instanton Induced Neutrino Majorana Masses in CFT Orientifolds with MSSM-like spectra
Ibáñez, L E; Uranga, Angel M
2007-01-01
Recently it has been shown that string instanton effects may give rise to neutrino Majorana masses in certain classes of semi-realistic string compactifications. In this paper we make a systematic search for supersymmetric MSSM-like Type II Gepner orientifold constructions admitting boundary states associated with instantons giving rise to neutrino Majorana masses and other L- and/or B-violating operators. We analyze the zero mode structure of D-brane instantons on general type II orientifold compactifications, and show that only instantons with O(1) symmetry can have just the two zero modes required to contribute to the 4d superpotential. We however discuss how the addition of fluxes and/or possible non-perturbative extensions of the orientifold compactifications would allow also instantons with Sp(2) and U(1) symmetries to generate such superpotentials. In the context of Gepner orientifolds with MSSM-like spectra, we find no models with O(1) instantons with just the required zero modes to generate a neutrin...
Proposal for non-BPS D-brane action
Kluson, J
2000-01-01
In this short note we would like to propose a form for the action of a non-BPS D-brane, which will be manifestly supersymmetric invariant and T-duality covariant. We also explicitly show that tachyon condensation on the world-volume of this brane leads to the Dirac-Born-Infeld action for BPS D(p-1)-brane.
Chaotic Cascades for D-branes on Singularities
Franco, S; Herzog, C; Walcher, J; Franco, Sebastian; He, Yang-Hui; Herzog, Christopher; Walcher, Johannes
2004-01-01
We briefly review our work on the cascading renormalization group flows for gauge theories on D-branes probing Calabi-Yau singularities. Such RG flows are sometimes chaotic and exhibit duality walls. We construct supergravity solutions dual to logarithmic flows for these theories. We make new observations about a surface of conformal theories and more complicated supergravity solutions.
SUSY in Silico: numerical D-brane bound state spectroscopy
Anous, Tarek
2015-01-01
We numerically construct BPS and non-BPS wavefunctions of an $\\mathcal{N}=4$ quiver quantum mechanics with two abelian nodes and a single arrow. This model captures the dynamics of a pair of wrapped D-branes interacting via a single light string mode. A dimensionless parameter $\
Minimal left-right symmetric intersecting D-brane model
Anchordoqui, Luis A; Goldberg, Haim; Huang, Xing; Lust, Dieter; Taylor, Tomasz R
2016-01-01
We investigate left-right symmetric extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. The left-handed and right-handed fermions transform as doublets under Sp(1)_L and Sp(1)_R, and so their masses must be generated by the introduction of Higgs fields in a bi-fundamental (2,2) representation under the two Sp(1) gauge groups. For such D-brane configurations the left-right symmetry must be broken by Higgs fields in the doublet representation of Sp(1)_R and therefore Majorana mass terms are suppressed by some higher physics scale. The left-handed and right-handed neutrinos pair up to form Dirac fermions which maneuver the decay widths of the right-handed W' boson to yield comparable branching fractions into dilepton and dijets channels. Using the most recent searches at LHC13 Run II with 2016 data we constrain the (g_R, m_{W'}) parameter space. Our ana...
D-Brane superstrings and new perspective of our world
Hashimoto, Koji
2012-01-01
Superstring theory is a promising theory which can potentially unify all the forces and the matters in particle physics. A new multi-dimensional object which is called "D-brane" was found. It drastically changed our perspective of a unified world. We may live on membrane-like hypersurfaces in higher dimensions ("braneworld scenario"), or we can create blackholes at particle accelarators, or the dynamics of quarks is shown to be equivalent to the higher dimensional gravity theory. All these scenarios are explained in this book with plain words but with little use of equations and with many figures. The book starts with a summary of long-standing problems in elementary particle physics and explains the D-branes and many applications of them. It ends with future roads for a unified ultimate theory of our world.
D-brane. Superstrings and new perspective of our world
Energy Technology Data Exchange (ETDEWEB)
Hashimoto, Koji [RIKEN, Saitama, Wako (Japan). Mathematical Physics Lab.
2012-07-01
Superstring theory is a promising theory which can potentially unify all the forces and the matters in particle physics. A new multi-dimensional object which is called ''D-brane'' was found. It drastically changed our perspective of a unified world. We may live on membrane-like hypersurfaces in higher dimensions (''braneworld scenario''), or we can create blackholes at particle accelerators, or the dynamics of quarks is shown to be equivalent to the higher dimensional gravity theory. All these scenarios are explained in this book with plain words but with little use of equations and with many figures. The book starts with a summary of long-standing problems in elementary particle physics and explains the D-branes and many applications of them. It ends with future roads for a unified ultimate theory of our world. (orig.)
D-branes in N=2 Liouville and its mirror
Israel, D; Troost, J; Israel, Dan; Pakman, Ari; Troost, Jan
2004-01-01
We study D-branes in the mirror pair N=2 Liouville / supersymmetric SL(2,R)/U(1) coset superconformal field theories. We build D0, D1 and D2 branes, on the basis of the boundary state construction for the Euclidean AdS(3) conformal field theory. We also construct D0-branes in an orbifold that rotates the angular direction of the cigar. We show how the poles of correlators associated to localized states and bulk interactions naturally decouple in the one-point functions of localized and extended branes. We stress the role played in the analysis of D-brane spectra by primaries in SL(2,R)/U(1) which are descendents of the parent theory.
Non-commutative tachyon action and D-brane geometry
Herbst, Manfred; Kreuzer, M; Herbst, Manfred; Kling, Alexander; Kreuzer, Maximilian
2002-01-01
We analyse open string correlators in non-constant background fields, including the metric $g$, the antisymmetric $B$-field, and the gauge field $A$. Working with a derivative expansion for the background fields, but exact in their constant parts, we obtain a tachyonic on-shell condition for the inserted functions and extract the kinetic term for the tachyon action. The 3-point correlator yields a non-commutative tachyon potential. We also find a remarkable feature of the differential structure on the D-brane: Although the boundary metric $G$ plays an essential role in the action, the natural connection on the D-brane is the same as in closed string theory, i.e. it is compatible with the bulk metric and has torsion $H=dB$. This means, in particular, that the parallel transport on the brane is independent of the gauge field $A$.
Intersecting D-branes and black hole entropy
Behrndt, Klaus; Bergshoeff, Eric
1996-01-01
In four dimensions there are 4 different types of extremal Maxwell/scalar black holes characterized by a scalar coupling parameter a with a = 0, 1/âˆš3, 1, âˆš3. These black holes can be described as intersections of ten-dimensional non-singular Ramond-Ramond objects, i.e, D-branes, waves and Taub-N
Cosmological constant and gravitational theory on D-brane
Shiromizu, T; Torii, T; Shiromizu, Tetsuya; Koyama, Kazuya; Torii, Takashi
2003-01-01
In a toy model we derive the gravitational equation on a self-gravitating curved D-brane. The effective theory on the brane is drastically changed from the ordinal Einstein equation. The net cosmological constant on the brane depends on a tuning between the brane tension and the brane charges. Moreover, non-zero matter stress tensor exists if the net cosmological constant is not zero. This fact indicates a direct connection between matters on the brane and the dark energy.
Linear Sigma Model Toolshed for D-brane Physics
Energy Technology Data Exchange (ETDEWEB)
Hellerman, Simeon
2001-08-23
Building on earlier work, we construct linear sigma models for strings on curved spaces in the presence of branes. Our models include an extremely general class of brane-worldvolume gauge field configurations. We explain in an accessible manner the mathematical ideas which suggest appropriate worldsheet interactions for generating a given open string background. This construction provides an explanation for the appearance of the derived category in D-brane physic complementary to that of recent work of Douglas.
Some phenomenology of intersecting D-brane models
Energy Technology Data Exchange (ETDEWEB)
Kane, Gordon L.; Kumar, Piyush; /Michigan U., MCTP; Lykken, Joseph D.; /Fermilab; Wang, Ting T.; /Michigan U., MCTP
2004-11-01
We present some phenomenology of a new class of intersecting D-brane models. Soft SUSY breaking terms for these models are calculated in the complex structure (u)-moduli dominant SUSY breaking approach (in type IIA). In this case, the dependence of the soft terms on the Yukawas and Wilson lines drops out. These soft terms have a different pattern compared to the usual heterotic string models. Phenomenological implications for dark matter are discussed.
D-brane superpotentials: Geometric and worldsheet approaches
Energy Technology Data Exchange (ETDEWEB)
Baumgartl, Marco, E-mail: m.baumgartl@physik.uni-muenchen.d [Arnold Sommerfeld Center, Ludwig-Maximilians-Universitaet, Theresienstr. 37, Muenchen 80333 (Germany); Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, Garching 85748 (Germany); Brunner, Ilka, E-mail: ilka.brunner@physik.uni-muenchen.d [Arnold Sommerfeld Center, Ludwig-Maximilians-Universitaet, Theresienstr. 37, Muenchen 80333 (Germany); Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, Garching 85748 (Germany); Soroush, Masoud, E-mail: masoud.soroush@physik.uni-muenchen.d [Arnold Sommerfeld Center, Ludwig-Maximilians-Universitaet, Theresienstr. 37, Muenchen 80333 (Germany); Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, Garching 85748 (Germany)
2011-02-21
From the worldsheet perspective, the superpotential on a D-brane wrapping internal cycles of a Calabi-Yau manifold is given as a generating functional for disk correlation functions. On the other hand, from the geometric point of view, D-brane superpotentials are captured by certain chain integrals. In this work, we explicitly show for branes wrapping internal two-cycles how these two different approaches are related. More specifically, from the worldsheet point of view, D-branes at the Landau-Ginzburg point have a convenient description in terms of matrix factorizations. We use a formula derived by Kapustin and Li to explicitly evaluate disk correlators for families of D2-branes. On the geometry side, we then construct a three-chain whose period gives rise to the effective superpotential and show that the two expressions coincide. Finally, as an explicit example, we choose a particular compact Calabi-Yau hypersurface and compute the effective D2-brane superpotential in different branches of the open moduli space, in both geometric and worldsheet approaches.
Phenomenological analysis of D-brane Pati-Salam vacua
Anastasopoulos, P.; Leontaris, G. K.; Vlachos, N. D.
2010-05-01
In the present work, we perform a phenomenological analysis of the effective low energy models with Pati-Salam (PS) gauge symmetry derived in the context of D-branes. The main issue in these models arises from the fact that the right-handed fermions and the PS-symmetry breaking Higgs field transform identically under the symmetry, causing unnatural matter-Higgs mixing effects. We argue that this problem can be solved in particular D-brane setups where these fields arise in different intersections. We further observe that whenever a large Higgs mass term is being generated in a particular class of mass spectra, a splitting mechanism -reminiscent of the doublet triplet splitting- may protect the neutral Higgs components from becoming heavy. We analyze the implications of each individual representation available in these models in order to specify the minimal spectrum required to build up a consistent model that reconciles the low energy data. A short discussion is devoted to the effects of stringy instanton corrections, particularly those generating missing Yukawa couplings and contributing to the fermion mass textures. We discuss the correlations of the intersecting D-brane spectra with those obtained from Gepner constructions and analyze the superpotential, the resulting mass textures and the low energy implications of some examples of the latter along the lines proposed above.
Orientifolding in N = 2 Superspace
Robles-Llana, D.; Rocek, M.; Saueressig, Frank; Theis, U.; Vandoren, S.
2007-01-01
We discuss orientifold projections on superspace effective actions for hypermultiplets. We present a simple and new mechanism that allows one to find the K¨ahler potential and complex structure for the N = 1 theory directly in terms of the parent N = 2 theory. As an application, we demonstrate our m
Categories of Massless D-Branes and del Pezzo Surfaces
Addington, Nicolas
2013-01-01
In analogy with the physical concept of a massless D-brane, we define a notion of "Q-masslessness" for objects in the derived category. This is defined in terms of monodromy around singularities in the stringy Kahler moduli space and is relatively easy to study using spherical functors. We consider several examples in which del Pezzo surfaces and other rational surfaces in Calabi-Yau threefolds are contracted. For precisely the del Pezzo surfaces that can be written as hypersurfaces in weighted P3, the category of Q-massless objects is a "fractional Calabi-Yau" category of graded matrix factorizations.
D5 elliptic fibrations: non-Kodaira fibers and new orientifold limits of F-theory
Esole, Mboyo; Yau, Shing-Tung
2011-01-01
A D5 elliptic fibration is a fibration whose generic fiber is modeled by the complete intersection of two quadric surfaces in P3. They provide simple examples of elliptic fibrations admitting a rich spectrum of singular fibers (not all on the list of Kodaira) without introducing singularities in the total space of the fibration and therefore avoiding a discussion of their resolutions. We study systematically the fiber geometry of such fibrations using Segre symbols and compute several topological invariants. We present for the first time Sen's (orientifold) limits for D5 elliptic fibrations. These orientifolds limit describe different weak coupling limits of F-theory to type IIB string theory giving a system of three brane-image-brane pairs in presence of a Z_2 orientifold. The orientifold theory is mathematically described by the double cover the base of the elliptic fibration. Such orientifold theories are characterized by a transition from a semi-stable singular fiber to an unstable one. In this paper, we ...
D-branes and Short Distances in String Theory
Douglas, M R; Pouliot, P; Shenker, S H; Douglas, Michael R.; Kabat, Daniel; Pouliot, Philippe; Shenker, Stephen H.
1996-01-01
We study the behavior of D-branes at distances far shorter than the string length scale~$l_s$. We argue that short-distance phenomena are described by the IR behavior of the D-brane world-volume quantum theory. This description is valid until the brane motion becomes relativistic. At weak string coupling 0-brane quantum mechanics to study 0-brane collisions and find structure at length scales corresponding to the eleven-dimensional Planck length ($\\lp11 ($\\R11 \\sim \\gs l_s$). We use 0-branes to probe non-trivial geometries and topologies at sub-stringy scales. We study the 0-brane 4-brane system, calculating the 0-brane moduli space metric, and find the bound state at threshold, which has characteristic size $\\lp11$. We examine the blowup of an orbifold and are able to resolve the resulting $S^2$ down to size $\\lp11$. A 0-brane with momentum approaching $1/\\R11$ is able to explore a larger configuration space in which the blowup is embedded. Analogous phenomena occur for small instantons. We finally turn to 1...
Phenomenological analysis of D-brane Pati-Salam vacua
Anastasopoulos, Pascal; Vlachos, Nikolaos D
2010-01-01
In the present work we perform a phenomenological analysis of the effective low energy models with Pati-Salam (PS) gauge symmetry derived in the context of D-branes. A main issue in these models arises from the fact that the right-handed fermions and the PS-symmetry breaking Higgs field transform identically under the PS symmetry, causing unnatural matter-Higgs mixing effects. We argue that this problem could be solved in particular D-brane setups where these fields arise in different intersections. We further observe that whenever a large Higgs mass term is generated in a particular class of mass spectra, a splitting mechanism -reminiscent of the doublet triplet splitting- may protect the neutral Higgs components from a heavy mass term. We analyze the implications of each individual representation which in principle is available in these models in order to specify the minimal spectrum required to build up a consistent PS model which reconciles the low energy data. A short discussion is devoted on the effects...
D-branes in T-fold conformal field theory
Kawai, Shinsuke
2008-01-01
We investigate boundary dynamics of orbifold conformal field theory involving T-duality twists. Such models typically appear in contexts of non-geometric string compactifications that are called monodrofolds or T-folds in recent literature. We use the framework of boundary conformal field theory to analyse the models from a microscopic world-sheet perspective. In these backgrounds there are two kinds of D-branes that are analogous to bulk and fractional branes in standard orbifold models. The bulk D-branes in T-folds allow intuitive geometrical interpretations and are consistent with the classical analysis based on the doubled torus formalism. The fractional branes, on the other hand, are `non-geometric' at any point in the moduli space and their geometric counterparts seem to be missing in the doubled torus analysis. We compute cylinder amplitudes between the bulk and fractional branes, and find that the lightest modes of the open string spectra show intriguing non-linear dependence on the moduli (location o...
Backreacting D-brane instantons on branes at singularities
García-Valdecasas Tenreiro, Eduardo; Uranga, Angel
2017-08-01
Non-perturbative D-brane instanton effects in 4d N=1 string compactifications can be geometrized in terms of a backreacted generalized geometry. We extend earlier results to setups in which the D-brane instanton is charged under the 4d gauge symmetries, and show that the backreacted topology yields the correct charged field theory operators in the 4d effective action. In type IIA models with D6-branes, the backreaction of D2-brane instantons forces the recombination of D6-branes, such that the 4d charged field theory operators arise from basic worldsheet instantons in the backreacted geometry. We provide large classes of examples of D2-brane instanton effects on intersecting D6-brane systems in local models mirror to D3-branes at singularities. The backreacted geometry and the field theory operators are easily encoded in terms of simple operations in the graphs arising from the underlying dimer diagrams. This description agrees, in the appropriate cases, with the complex deformations triggered by certain fractional branes at the bottom of duality cascades.
NS-branes in 5d brane world models
Park, Eun Kyung
2010-01-01
We study codimension-1 brane solutions of the 5d brane world models compactified on $S_1 / \\mathbb{Z}_2$. In string theoretical setup they suggest that the background branes located at orbifold fixed points should be NS-branes (in the five dimensional sense), rather than D-branes. Indeed, the existence of the background NS-branes is indispensable to obtain flat geometry $M_4 \\times S_1 / \\mathbb{Z}_2$ where $M_4$ represents the 4d Minkowski spacetime, and without these branes the 5d metric becomes singular everywhere. This result is very reminiscent of the $(p+3)$d effective string theory \\cite{1} where the NS-NS type $p$-brane is indispensable to obtain a flat geometry $R_2$ or $R_2 /\\mathbb{Z}_n$ on the transverse dimensions. Without this NS-NS type $p$-brane the 2d transverse space becomes a pin-shaped singular space. The correspondence between these two theories leads us to a conjecture that the whole flat backgrounds of the string theory inherently invovle the NS-branes implicitly in their ansatz, and he...
On Orientifolds of c=1 Orbifolds
Dijkstra, T P T; Riccioni, F; Schellekens, Adrian Norbert
2003-01-01
The aim of this paper is to study orientifolds of c=1 conformal field theories. A systematic analysis of the allowed orientifold projections for c=1 orbifold conformal field theories is given. We compare the Klein bottle amplitudes obtained at rational points with the orientifold projections that we claim to be consistent for any value of the orbifold radius. We show that the recently obtained Klein bottle amplitudes corresponding to exceptional modular invariants, describing bosonic string theories at fractional square radius, are also in agreement with those orientifold projections.
T-duality and actions for non-BPS D-branes
Bergshoeff, EA; de Roo, M; de Wit, TC; Eyras, E; Panda, S; Wit, Tim C. de
2000-01-01
We employ T-duality to restrict the tachyon dependence of effective actions for non-BPS D-branes. For the Born-Infeld part the criteria of T-duality and supersymmetry are satisfied by a simple extension of the D-brane Born-Infeld action.
Fiol, Bartomeu; Torrents, Genis
2014-01-01
We compute the exact vacuum expectation value of circular Wilson loops for Euclidean ${\\cal N}=4$ super Yang-Mills with $G=SO(N),Sp(N)$, in the fundamental and spinor representations. These field theories are dual to type IIB string theory compactified on $AdS_5\\times {\\mathbb R} {\\mathbb P}^5$ plus certain choices of discrete torsion, and we use our results to probe this holographic duality. We first revisit the LLM-type geometries having $AdS_5\\times {\\mathbb R} {\\mathbb P}^5$ as ground state. Our results clarify and refine the identification of these LLM-type geometries as bubbling geometries arising from fermions on a half harmonic oscillator. We furthermore identify the presence of discrete torsion with the one-fermion Wigner distribution becoming negative at the origin of phase space. We then turn to the string world-sheet interpretation of our results and argue that for the quantities considered they imply two features: first, the contribution coming from world-sheets with a single crosscap is closely ...
Exceptional collections and D-branes probing toric singularities
Herzog, C P; Herzog, Christopher P.; Karp, Robert L.
2006-01-01
We demonstrate that a strongly exceptional collection on a singular toric surface can be used to derive the gauge theory on a stack of D3-branes probing the Calabi-Yau singularity caused by the surface shrinking to zero size. A strongly exceptional collection, i.e., an ordered set of sheaves satisfying special mapping properties, gives a convenient basis of D-branes. We find such collections and analyze the gauge theories for weighted projective spaces, and many of the Y^{p,q} and L^{p,q,r} spaces. In particular, we prove the strong exceptionality for all p in the Y^{p,p-1} case, and similarly for the Y^{p,p-2r} case.
Dark Solitons, D-branes and Noncommutative Tachyon Field Theory
Giaccari, Stefano
2016-01-01
In this paper we discuss the boson/vortex duality by mapping the Gross-Pitaevskii theory into an effective string theory, both with and without boundaries. Through the effective string theory, we find the Seiberg-Witten map between the commutative and the noncommutative tachyon field theories, and consequently identify their soliton solutions with the D-branes in the effective string theory. We perform various checks of the duality map and the identification of classical solutions. This new insight of the duality between the Gross-Pitaevskii theory and the effective string theory allows us to test many results of string theory in Bose-Einstein condensates, and at the same time help us understand the quantum behavior of superfluids and cold atom systems.
A delicate universe: compactification obstacles to D-brane inflation.
Baumann, Daniel; Dymarsky, Anatoly; Klebanov, Igor R; McAllister, Liam; Steinhardt, Paul J
2007-10-01
We investigate whether explicit models of warped D-brane inflation are possible in string compactifications. To this end, we study the potential for D3-brane motion in a warped conifold that includes holomorphically embedded D7-branes involved in moduli stabilization. The presence of the D7-branes significantly modifies the inflaton potential. We construct an example based on a very simple and symmetric embedding due to Kuperstein, z1= const, in which it is possible to fine-tune the potential so that slow-roll inflation can occur. The resulting model is rather delicate: inflation occurs in the vicinity of an inflection point, and the cosmological predictions are extremely sensitive to the precise shape of the potential.
Worldsheet approaches to D-branes on supersymmetric cycles
Energy Technology Data Exchange (ETDEWEB)
Govindarajan, Suresh E-mail: suresh@chaos.iitm.ernet.in; Jayaraman, T. E-mail: jayaram@imsc.ernet.in; Sarkar, Tapobrata E-mail: sarkar@imsc.ernet.in
2000-07-31
We consider D-branes wrapped around supersymmetric cycles of Calabi-Yau manifolds from the viewpoint of N=2 Landau-Ginzburg models with boundary as well as by consideration of boundary states in the corresponding Gepner models. The Landau-Ginzburg approach enables us to provide a target space interpretation for the boundary states. The boundary states are obtained by applying Cardy's procedure to combinations of characters in the Gepner models which are invariant under spectral flow. We are able to relate the two descriptions using common discrete symmetries occurring in the two descriptions. We thus provide an extension to the boundary, the bulk correspondence between Landau-Ginzburg orbifolds and the corresponding Gepner models.
D-branes, symplectomorphisms and noncommutative gauge theories
Energy Technology Data Exchange (ETDEWEB)
Martin, I.; Ovalle, J.; Restuccia, A
2001-09-01
It is shown that the dual of the double compactified D=11 Supermembrane and a suitable compactified D=10 Super 4D-brane with nontrivial wrapping on the target space may be formulated as non-commutative gauge theories. The Poisson bracket over the world-volume is intrinsically defined in terms of the minima of the hamiltonian of the theory, which may be expressed in terms of a non degenerate 2-form. A deformation of the Poisson bracket in terms of the Moyal brackets is then performed. A non-commutative gauge theory in terms of the Moyal star bracket is obtained. It is shown that all these theories may be described in terms of symplectic connections on symplectic fibrations, the world volume being its base manifold and the (sub)group of volume preserving diffeomorphisms, p = 2 (p > 2), generate the symplectomorphisms which preserve the (infinite dimensional) Poisson bracket of the fibration.
D-branes, symplectomorphisms and noncommutative gauge theories
Martín, I.; Ovalle, J.; Restuccia, A.
It is shown that the dual of the double compactified D=11 Supermembrane and a suitable compactified D=10 Super 4D-brane with nontrivial wrapping on the target space may be formulated as non-commutative gauge theories. The Poisson bracket over the world-volume is intrinsically defined in terms of the minima of the hamiltonian of the theory, which may be expressed in terms of a non degenerate 2-form. A deformation of the Poisson bracket in terms of the Moyal brackets is then performed. A non-commutative gauge theory in terms of the Moyal star bracket is obtained. It is shown that all these theories may be described in terms of symplectic connections on symplectic fibrations, the world volume being its base manifold and the (sub)group of volume preserving diffeomorphisms, p = 2 ( p > 2), generate the symplectomorphisms which preserve the (infinite dimensional) Poisson bracket of the fibration.
Connecting Localization and Wall-Crossing via D-Branes
Chang, Chih-Kai; Jain, Dharmesh; Lee, Norton
2015-01-01
We demonstrate explicitly that the vacuum expectation values (vevs) of BPS line operators in 4d N=2 super Yang-Mills theory compactified on a circle, computed by localization techniques, can be expanded in terms of Darboux coordinates as proposed by Gaiotto, Moore, and Neitzke [arXiv:1006.0146]. However, we need to refine the expansion by including additional novel monopole bubbling contributions to obtain a precise match. Using D-brane realization of these singular BPS line operators, we derive and incorporate the monopole bubbling contributions as well as predict the degeneracies of framed BPS states contributing to the line operator vevs in the limit of vanishing simultaneous spatial and R-symmetry rotation fugacity parameter.
Challenges for D-brane large-field inflation with stabilizer fields
Landete, Aitor; Marchesano, Fernando; Wieck, Clemens
2016-09-01
We study possible string theory compactifications which, in the low-energy limit, describe chaotic inflation with a stabilizer field. We first analyze type IIA setups where the inflationary potential arises from a D6-brane wrapping an internal three-cycle, and where the stabilizer field is either an open-string or bulk Kähler modulus. We find that after integrating out the relevant closed-string moduli consistently, tachyonic directions arise during inflation which cannot be lifted. This is ultimately due to the shift symmetries of the type IIA Kähler potential at large compactification volume. This motivates us to search for stabilizer candidates in the complex structure sector of type IIB orientifolds, since these fields couple to D7-brane Wilson lines and their shift symmetries are generically broken away from the large complex structure limit. However, we find that in these setups the challenge is to obtain the necessary hierarchy between the inflationary and Kaluza-Klein scales.
Challenges for D-brane large-field inflation with stabilizer fields
Landete, Aitor; Wieck, Clemens
2016-01-01
We study possible string theory compactifications which, in the low-energy limit, describe chaotic inflation with a stabilizer field. We first analyze type IIA setups where the inflationary potential arises from a D6-brane wrapping an internal three-cycle, and where the stabilizer field is either an open-string or bulk K\\"ahler modulus. We find that after integrating out the relevant closed-string moduli consistently, tachyonic directions arise during inflation which cannot be lifted. This is ultimately due to the shift symmetries of the type IIA K\\"ahler potential at large compactification volume. This motivates us to search for stabilizer candidates in the complex structure sector of type IIB orientifolds, since these fields couple to D7-brane Wilson lines and their shift symmetries are generically broken away from the large complex structure limit. However, we find that in these setups the challenge is to obtain the necessary hierarchy between the inflationary and Kaluza-Klein scales.
Orientifold Planar Equivalence: The Chiral Condensate
DEFF Research Database (Denmark)
Armoni, Adi; Lucini, Biagio; Patella, Agostino
2008-01-01
The recently introduced orientifold planar equivalence is a promising tool for solving non-perturbative problems in QCD. One of the predictions of orientifold planar equivalence is that the chiral condensates of a theory with $N_f$ flavours of Dirac fermions in the symmetric (or antisymmetric...
On Susy Standard-like models from orbifolds of D=6 Gepner orientifolds
Aldazabal, G; Juknevich, J E
2006-01-01
As a further elaboration of the proposal of Ref. [1] we address the construction of Standard-like models from configurations of stacks of orientifold planes and D-branes on an internal space with the structure ${(Gepner model)^{c=6} \\times T^2}/Z_N$. As a first step, the construction of D=6 Type II B orientifolds on Gepner points, in the diagonal invariant case and for both, odd and even, affine levels is discussed. We build up the explicit expressions for B-type boundary states and crosscaps and obtain the amplitudes among them. From such amplitudes we read the corresponding spectra and the tadpole cancellation equations. Further compactification on a T^2 torus, by simultaneously orbifolding the Gepner and the torus internal sectors, is performed. The embedding of the orbifold action in the brane sector breaks the original gauge groups and leads to N=1 supersymmetric chiral spectra. Whenever even orbifold action on the torus is considered, new branes, with worldvolume transverse to torus coordinates, must be...
Massless D-Branes on Calabi-Yau Threefolds and Monodromy
Aspinwall, Paul S; Horja, R P; Aspinwall, Paul S.; Karp, Robert L.
2002-01-01
We analyze the link between the occurrence of massless B-type D-branes for specific values of moduli and monodromy around such points in the moduli space. This allows us to propose a classification of all massless B-type D-branes at any point in the moduli space of Calabi-Yau's. This classification then justifies a previous conjecture due to Horja for the general form of monodromy. Our analysis is based on using monodromies around points in moduli space where a single D-brane becomes massless to generate monodromies around points where an infinite number become massless. We discuss the various possibilities within the classification.
Supersymmetric Composite Models on Intersecting D-branes
Kitazawa, N
2004-01-01
We construct supersymmetric composite models of quarks and leptons from type IIA T^6/(Z_2 x Z_2) orientifolds with intersecting D6-branes. In case of T^6 = T^2 x T^2 x T^2 with no tilted T^2, a composite model of the supersymmetric SU(5) grand unified theory with three generations is constructed. In case of that one T^2 is tilted, a composite model with SU(3)_c x SU(2)_L x U(1)_Y gauge symmetry with three generations is constructed. These models are not realistic, but contain fewer additional exotic particles and U(1) gauge symmetries due to the introduction of the compositeness of quarks and leptons. The mu-term of Higgs fields can be naturally generated through the exponentially suppressed Yukawa interaction among "preons".
Boundary fermions, coherent sheaves and D-branes on Calabi-Yau manifolds
Energy Technology Data Exchange (ETDEWEB)
Govindarajan, Suresh E-mail: suresh@chaos.iitm.ernet.in; Jayaraman, T. E-mail: jayaram@imsc.ernet.in
2001-12-10
We construct boundary conditions in the gauged linear sigma model for B-type D-branes on Calabi-Yau manifolds that correspond to coherent sheaves given by the cohomology of a monad. This necessarily involves the introduction of boundary fields, and in particular, boundary fermions. The large-volume monodromy for these D-brane configurations is implemented by the introduction of boundary contact terms. We also discuss the construction of D-branes associated to coherent sheaves that are the cohomology of complexes of arbitrary length. We illustrate the construction using examples, specifically those associated with the large-volume analogues of the Recknagel-Schomerus states with no moduli. Using some of these examples we also construct D-brane states that arise as bound states of the above rigid configurations and show how moduli can be counted in these cases.
D-Brane Probes in the Matrix Model
Ferrari, Frank
2013-01-01
Recently, a new approach to large N gauge theories, based on a generalization of the concept of D-brane probes to any gauge field theory, was proposed. In the present note, we compute the probe action in the one matrix model with a quartic potential. This allows to illustrate several non-trivial aspects of the construction in an exactly solvable set-up. One of our main goal is to test the bare bubble approximation. The approximate free energy found in this approximation, which can be derived from a back-of-an-envelope calculation, matches the exact result for all values of the 't Hooft coupling with a surprising accuracy. Another goal is to illustrate the remarkable properties of the equivariant partial gauge-fixing procedure, which is at the heart of the formalism. For this we use a general xi-gauge to compute the brane action. The action depends on xi in a very non-trivial way, yet we show explicitly that its critical value does not and coincide with twice the free energy, as required by general consistency...
Strings, boundary fermions and coincident D-branes
Wulff, L
2007-01-01
This thesis describes an attempt to write down covariant actions for coincident D-branes using so-called boundary fermions instead of matrices to describe the non-abelian fields. These fermions can be thought of as Chan-Paton degrees of freedom for the open string. It is shown that by gauge-fixing and by suitably quantizing these boundary fermions the non-abelian action that is known, the Myers action, can be reproduced. Furthermore it is shown that under natural assumptions, unlike the Myers action, the action formulated using boundary fermions also posseses kappa-symmetry when formulated on superspace. Another aspect of string theory discussed in this thesis is that of tensionless strings. These are of great interest for example because of their possible relation to higher spin gauge theories via the AdS/CFT-correspondence. The tensionless superstring in a plane wave background, a Penrose limit of the near-horizon geometry of a stack of D3-branes, is considered and compared to the tensile case.
Metastable vacua and D-branes at the conifold
Argurio, R; Franco, S; Kachru, S; Argurio, Riccardo; Bertolini, Matteo; Franco, Sebastian; Kachru, Shamit
2007-01-01
We consider quiver gauge theories arising on D-branes at simple Calabi-Yau singularities (quotients of the conifold). These theories have metastable supersymmetry breaking vacua. The field theoretic mechanism is basically the one exhibited by the examples of Intriligator, Seiberg and Shih in SUSY QCD. In a dual description, the SUSY breaking is captured by the presence of anti-branes. In comparison to our earlier related work, the main improvements of the present construction are that we can reach the free magnetic range of the SUSY QCD theory where the existence of the metastable vacua is on firm footing, and we can see explicitly how the small masses for the quark flavors (necessary to the existence of the SUSY breaking vacua) are dynamically stabilized. One crucial mass term is generated by a stringy instanton. Finally, our models naturally incorporate R-symmetry breaking in the non-supersymmetric vacuum, in a way similar to the examples of Kitano, Ooguri and Ookouchi.
On alpha'-corrections to D-brane solutions
De Haro, S; Skenderis, K; Haro, Sebastian de; Sinkovics, Annamaria; Skenderis, Kostas
2003-01-01
We discuss the computation of the leading corrections to D-brane solutions due to higher derivative terms in the corresponding low energy effective action. We develop several alternative methods for analyzing the problem. In particular, we derive an effective one-dimensional action from which the field equations for spherically symmetric two-block brane solutions can be derived, show how to obtain first order equations, and discuss a few other approaches. We integrate the equations for extremal branes and obtain the corrections in terms of integrals of the evaluation of the higher derivative terms on the lowest order solution. To obtain completely explicit results one would need to know all leading higher derivative corrections which at present are not available. One of the known higher derivative terms is the R^4 term, and we obtain the corrections to the D3 brane solution due to this term alone. We note, however, that (unknown at present) higher terms depending on F_5 are expected to modify our result. We a...
A Note on Holographic Renormalization of Probe D-Branes
Benincasa, Paolo
2009-01-01
A great deal of progress has been recently made in the study of holography for non-conformal branes. Considering the near-horizon limit of backgrounds generated by such branes, we discuss the holographic renormalization of probe D-branes in these geometries. More specifically, we discuss in some detail systems with a codimension-one defect. For this class of systems, the mode which describes the probe branes wrapping a maximal 2-sphere in the transverse space behaves like a free massive scalar propagating in a higher-dimensional (asymptotically) AdS_{q+1}-space. The counterterms needed are then the ones of a free massive scalar in asymptotically AdS_{q+1}. The original problem can be recovered by compactifying the AdS-space on a torus and finally performing the analytic continuation of q to the value of interest, which can be fractional. We compute the one-point correlator for the operator dual to the embedding function. We finally comment on holographic renormalization in the more general cases of codimensio...
Low energy effective action on a self-gravitating D-brane
Onda, S; Koyama, K; Hayakawa, S; Onda, Sumitada; Shiromizu, Tetsuya; Koyama, Kazuya; Hayakawa, Shoko
2003-01-01
Recently the study of braneworld on the self-gravitating D-brane has been initiated and derived the gravitational equation on the brane by holographic and geometrical projection methods. Surprisingly, in common with these two methods, the matter on the brane cannot be the source of the gravity on the brane at leading order. In this paper we will propose the low energy effective action on the D-brane coupled with gravity which derives the same results.
IIB Soliton Spectra with All Fluxes Activated
Evslin, J
2003-01-01
Building upon an earlier proposal for the classification of fluxes, a sequence is proposed which generalizes the AHSS by computing type IIB string theory's group of conserved RR and also NS charges, which is conjectured to be a K-theory of dual pairs. As a test, the formalism of Maldacena, Moore and Seiberg (hep-th/0108100) is applied to classify D-branes, NS5-branes, F-strings and their dielectric counterparts in IIB compactified on a 3-sphere with both NS and RR background fluxes. The soliton spectra on the 3-sphere are then compared with the output of the sequence, as is the baryon spectrum in Witten's non-spin^c example, AdS^5xRP^5. The group of conserved charges is seen to change during Brown-Teitelboim-like phase transitions which change the effective cosmological constant.
D-branes in a Big Bang/Big Crunch Universe: Nappi-Witten Gauged WZW Model
Hikida, Y; Panigrahi, K L; Hikida, Yasuaki; Nayak, Rashmi R.; Panigrahi, Kamal L.
2005-01-01
We study D-branes in the Nappi-Witten model, which is a gauged WZW model based on (SL(2,R) x SU(2)) / (U(1) x U(1)). The model describes a four dimensional space-time consisting of cosmological regions with big bang/big crunch singularities and static regions with closed time-like curves. The aim of this paper is to investigate by D-brane probes whether there are pathologies associated with the cosmological singularities and the closed time-like curves. We first classify D-branes in a group theoretical way, and then examine DBI actions for effective theories on the D-branes. In particular, we show that D-brane metric from the DBI action does not include singularities, and wave functions on the D-branes are well behaved even in the presence of closed time-like curves.
D-Branes at Singularities A Bottom-Up Approach to the String Embedding of the Standard Model
Aldazabal, G; Quevedo, Fernando; Uranga, Angel M
2000-01-01
We propose a bottom-up approach to the building of particle physics models from string theory. Our building blocks are Type II D-branes which we combine appropriately to reproduce desirable features of a particle theory model: 1) Chirality ; 2) Standard Model group ; 3) N=1 or N=0 supersymmetry ; 4) Three quark-lepton generations. We start such a program by studying configurations of D=10, Type IIB D3-branes located at singularities. We study in detail the case of Z_N, N=1,0 supersymmetric orbifold singularities leading to the SM group or some left-right symmetricextension. In general, tadpole cancellation conditions require the presence of additional branes, e.g. D7-branes. For the N=1 supersymmetric case the unique twist leading to three quark-lepton generations is Z_3, predicting $\\sin^2\\theta_W=3/14=0.21$. The models obtained are the simplest semirealistic string models ever built. In the non-supersymmetric case there is a three-generation model for each Z_N, N>4, but the Weinberg angle is in general too ...
D-Branes at Singularities A Bottom-Up Approach to the String Embedding of the Standard Model
Aldazabal, G.; Quevedo, F.; Uranga, A.M.
2000-01-01
We propose a bottom-up approach to the building of particle physics models from string theory. Our building blocks are Type II D-branes which we combine appropriately to reproduce desirable features of a particle theory model: 1) Chirality ; 2) Standard Model group ; 3) N=1 or N=0 supersymmetry ; 4) Three quark-lepton generations. We start such a program by studying configurations of D=10, Type IIB D3-branes located at singularities. We study in detail the case of Z_N, N=1,0 supersymmetric orbifold singularities leading to the SM group or some left-right symmetricextension. In general, tadpole cancellation conditions require the presence of additional branes, e.g. D7-branes. For the N=1 supersymmetric case the unique twist leading to three quark-lepton generations is Z_3, predicting $\\sin^2\\theta_W=3/14=0.21$. The models obtained are the simplest semirealistic string models ever built. In the non-supersymmetric case there is a three-generation model for each Z_N, N>4, but the Weinberg angle is in general too ...
Dynamical Electroweak Symmetry Breaking in String Models with D-branes
Kitazawa, Noriaki
2009-01-01
The possibility of dynamical electroweak symmetry breaking by strong coupling gauge interaction in models with D-branes in String Theory is examined. Instead of elementary scalar Higgs doublet fields, the gauge symmetry with strong coupling (technicolor) is introduced. As the first step of this direction, a toy model, which is not fully realistic, is concretely analyzed in some detail. The model consists of D-branes and anti-D-branes at orbifold singularities in (T^2 x T^2 x T^2)/Z_3 which preserves supersymmetry. Supersymmetry is broken through the brane supersymmetry breaking. It is pointed out that the problem of large S parameter in dynamical electroweak symmetry breaking scenario may be solved by natural existence of kinetic term mixings between hypercharge U(1) gauge boson and massive anomalous U(1) gauge bosons. The problems to be solved toward constructing more realistic models are clarified in the analysis.
D-brane stability, geometric engineering, and monodromy in the Derived Category
Karp, R L
2005-01-01
We discuss aspects of topological B-type D-branes in the framework of the derived category of coherent sheaves on a Calabi-Yau 3-fold X. We analyze the link between massless D-branes and monodromies in the CFT moduli space. A classification of all massless D-branes at any point in the moduli space is conjectured, together with an associated monodromy. We test the conjectures in two independent ways. First we establish a composition formula for certain Fourier-Mukai functors, which is a consequence of the triangulated structure of D(X). Secondly, using pi-stability we rederive the stable soliton spectrum of the pure N=2 supersymmetric SU(2) Seiberg-Witten theory. In this approach, the simplicity of the spectrum rests on Grothendieck's theorem concerning vector bundles over P^1.
D-branes as coherent states in the open string channel
Cantcheff, Marcelo Botta
2007-01-01
We show that bosonic D-brane states may be represented as coherent states in an open string representation. By using the Thermo Field Dynamics (TFD) formalism, we may construct a condensed state of open string modes which encodes the information on the D-brane configuration. We also introduce a construction alternative to TFD, which does not require to assume thermal equilibrium. It is shown that the dynamics of the system, combined with geometric properties of the duplication rules of TFD, is sufficient to obtain the thermal states and their analytic continuations in a geometric fashion. We adopt this approach to show that bosonic D-brane states in the open string sector may also be built as boundary states in a special sense. Some implications of this study on the interpretation of the open/closed duality and on the kinematical/algebraic structure of an open string field theory are also commented.
Inflation on Fractional Branes: D--Brane Inflation as D--Term Inflation
Halyo, E
2004-01-01
We describe a D--brane inflation model which consists of two fractional D3 branes separated on a transverse $T^2 \\times K3$. Inflation arises due to the resolved orbifold singularity of $K3$ which corresponds to an anomalous D--term on the brane. Therefore D--brane inflation in the bulk corresponds to D--term inflation on the brane. The inflaton and the trigger field parametrize the interbrane distances on $T^2$ an $K3$ respectively. After inflation the branes reach a supersymmetric configuration in which they are at the origin of $T^2$ but separated along the $K3$ directions.
D-branes from Pure Spinor Superstring in AdS_5 x S^5 Background
Hanazawa, Sota
2016-01-01
We examine the surface term for the BRST transformation of the open pure spinor superstring in an AdS_5 x S^5 background. We find that the boundary condition to eliminate the surface term leads to a classification of possible configurations of 1/2 supersymmetric D-branes.
D-branes from pure spinor superstring in AdS5 × S5 background
Hanazawa, Sota; Sakaguchi, Makoto
2017-01-01
We examine the surface term for the BRST transformation of the open pure spinor superstring in an AdS5 ×S5 background. We find that the boundary condition to eliminate the surface term leads to a classification of possible configurations of 1/2 supersymmetric D-branes.
Weak gravity conjecture as a razor criterium for exotic D-brane instantons
Addazi, Andrea
2017-01-01
We discuss implications of weak gravity conjecture (WGC) for exotic D-brane instantons. In particular, WGC leads to indirect stringent bounds on non-perturbative superpotentials generated by exotic instantons with many implications for phenomenology: R-parity violating processes, neutrino mass, μ-problem, neutron-antineutron transitions and collider physics.
Discussing string extensions of the Standard Model in D brane world
Di Vecchia, P
2009-01-01
In this talk we will describe the problems that one encounters when one tries to connect string theory with particle phenomenology. Then, in order to have chiral matter describing quarks and leptons, we introduce the magnetized D branes. Finally, as an explicit example of a string extension of the Standard Model, we will describe the one constructed by Ibanez, Marchesano and Rabadan.
Discussing string extensions of the Standard Model in D brane world
Energy Technology Data Exchange (ETDEWEB)
Di Vecchia, Paolo [Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen O (Denmark); NORDITA, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)
2009-01-15
In this talk we will describe the problems that one encounters when one tries to connect string theory with particle phenomenology. Then, in order to have chiral matter describing quarks and leptons, we introduce the magnetized D branes. Finally, as an explicit example of a string extension of the Standard Model, we will describe the one constructed by Ibanez, Marchesano and Rabadan.
Remarks on Global Anomalies in RCFT Orientifolds
Gato-Rivera, Beatriz
2006-01-01
We check the list of supersymmetric standard model orientifold spectra of Dijkstra, Huiszoon and Schellekens for the presence of global anomalies, using probe branes. Absence of global anomalies is found to impose strong constraints, but in nearly all cases they are automatically satisfied by the solutions to the tadpole cancellation conditions.
Instanton Effects in Orientifold ABJM Theory
Moriyama, Sanefumi
2015-01-01
We investigate another supersymmetric Chern-Simons theory called orientifold ABJM theory, which replaces the unitary supergroup structure of the ABJM theory by an orthosymplectic one. The non-perturbative structure of it is completely clarified by considering the duplication of the quiver.
Orientifolds of Warped Throats from Toric Calabi-Yau Singularities
Retolaza, Ander
2016-01-01
We study the complex deformations of orientifolds of D3-branes at toric CY singularities, using their description in terms of dimer diagrams. We describe orientifold quotients that have fixed lines or fixed points in the dimer, and characterize the possibilities to deform them in terms of the behaviour of zig-zag paths under the orientifold symmetry. The resulting models are holographic duals to warped throats with orientifold planes. Our systematic construction provides a general class of configurations which includes models recently appeared in the context of de Sitter uplift by nilpotent goldstino or dynamical supersymmetry breaking.
Standard model-like D-brane models and gauge couplings
Energy Technology Data Exchange (ETDEWEB)
Hamada, Yuta [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Kobayashi, Tatsuo [Department of Physics, Hokkaido University, Sapporo 060-0810 (Japan); Uemura, Shohei, E-mail: uemura@gauge.scphys.kyoto-u.ac.jp [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)
2015-08-15
We systematically search intersecting D-brane models, which just realize the Standard Model chiral matter contents and gauge symmetry. We construct new classes of non-supersymmetric Standard Model-like models. We also study the gauge coupling constants of these models. The tree level gauge coupling is a function of the compactification moduli, the string scale, the string coupling and the winding numbers of D-branes. By tuning them, we examine whether the models can explain the experimental values of gauge couplings. As a result, we find that the string scale should be greater than 10{sup 14–15} GeV if the compactification scale and the string scale are of the same order.
Aspects Of D-branes : From Branes In Motion To Meson Spectroscopy
Winters, D J
2004-01-01
We discuss various aspects of D-branes, ranging from their basic properties as extended objects within string theory to their application, via the AdS/CFT correspondence, to the physics of gauge theories. Our initial emphasis is on the description of time-dependent, yet supersymmetric, brane configurations and to this end we first provide a review of established results on D- branes. We then investigate various supersymmetric brane intersections. Motivated by the recent results on supertubes, we investigate general constraints under which parallel brane-antibrane configurations are supersymmetric. Dual descriptions of these configurations involve systems of intersecting branes in relative motion. In particular, we find new supersymmetric configurations which are not related to a static brane intersection by a boost. In these new configurations, the intersection point moves at the speed of light. We then briefly review the AdS/CFT correspondence between string and gauge theories. Our emphasis here is on the re...
On the 3-form formulation of axion potentials from D-brane instantons
García-Valdecasas, Eduardo
2016-01-01
The study of axion models and quantum corrections to their potential has experienced great progress by phrasing the axion potential in terms of a 3-form field eating up the 2-form field dual to the axion. Such reformulation of the axion potential has been described for axion monodromy models, and for axion potentials from non-perturbative gauge dynamics. In this paper we propose a 3-form description of the axion potentials from non-gauge D-brane instantons. Interestingly, the required 3-form field does not arise in the underlying geometry, but rather shows up in the KK compactification in the generalized geometry obtained when the backreaction of the D-brane instanton is taken into account.
Superconformal index of N=3 orientifold theories
Imamura, Yosuke
2016-01-01
We analyze the superconformal index of the N=3 supersymmetric Z_k generalized orientifold theories recently proposed. In the large N limit we derive the index from the Kaluza-Klein modes in AdS_5 x S^5/Z_k, which are obtained from ones in AdS_5 x S^5 by a simple projection. For the ordinary Z_2 orientifold case the agreement with the gauge theory calculation is explicitly confirmed, and for Z_k with k > 2 we perform a few consistency checks with known results for N=3 theories. We also study finite N corrections by analyzing wrapped D3-branes and discrete torsions in the dual geometry.
Orientifold Planar Equivalence: The Quenched Meson Spectrum
Lucini, Biagio; Patella, Agostino; Rago, Antonio
2010-01-01
A numerical study of Orientifold Planar Equivalence is performed in SU(N) Yang-Mills theories for N=2,3,4,6. Quenched meson masses are extracted in the antisymmetric, symmetric and adjoint representations for the pseudoscalar and vector channels. An extrapolation of the vector mass as a function of the pseudoscalar mass to the large-N limit shows that the numerical results agree within errors for the three theories, as predicted by Orientifold Planar Equivalence. As a byproduct of the extrapolation, the size of the corrections up to O(1/N^3) are evaluated. A crucial prerequisite for the extrapolation is the determination of an analytical relationship between the corrections in the symmetric and in the antisymmetric representations, order by order in a 1/N expansion.
Global D-brane models with stabilised moduli and light axions
Cicoli, Michele
2012-01-01
We review recent attempts to try to combine global issues of string compactifications, like moduli stabilisation, with local issues, like semi-realistic D-brane constructions. We list the main problems encountered, and outline a possible solution which allows globally consistent embeddings of chiral models. We also argue that this stabilisation mechanism leads to an axiverse. We finally illustrate our general claims in a concrete example where the Calabi-Yau manifold is explicitly described by toric geometry.
Space-Time Uncertainty and Approaches to D-Brane Field Theory
Yoneya, Tamiaki
2007-01-01
In connection with the space-time uncertainty principle which gives a simple qualitative characterization of non-local or non-commutative nature of short-distance space-time structure in string theory, author's recent approaches toward field theories for D-branes are briefly outlined, putting emphasis on some key ideas lying in the background. The final section of the present report is devoted partially to a tribute to Yukawa on the occasion of the centennial of his birth.
Orientifolding of the ABJ Fermi gas
Okuyama, Kazumi
2016-01-01
The grand partition functions of ABJ theory can be factorized into even and odd parts under the reflection of fermion coordinate in the Fermi gas approach. In some cases, the even/odd part of ABJ grand partition function is equal to that of $\\mathcal{N}=5$ $O(n)\\times USp(n')$ theory, hence it is natural to think of the even/odd projection of grand partition function as an orientifolding of ABJ Fermi gas system. By a systematic WKB analysis, we determine the coefficients in the perturbative part of grand potential of such orientifold ABJ theory. We also find the exact form of the first few "half-instanton" corrections coming from the twisted sector of the reflection of fermion coordinate. For the Chern-Simons level $k=2,4,8$ we find closed form expressions of the grand partition functions of orientifold ABJ theory, and for $k=2,4$ we prove the functional relations among the grand partition functions conjectured in arXiv:1410.7658.
Domain walls in noncommutative gauge theories, folded D-branes, and communication with mirror world
Energy Technology Data Exchange (ETDEWEB)
Dubovsky, S.L.; Sibiryakov, S.M. E-mail: sibir@ms2.inr.ac.ru
2004-07-19
Noncommutative U(N) gauge theories at different N may be often thought of as different sectors of a single theory. For instance, U(1) theory possesses a sequence of vacua labeled by an integer parameter N, and the theory in the vicinity of the Nth vacuum coincides with the U(N) noncommutative gauge theory. We construct domain walls on noncommutative plane, which separate vacua with different gauge groups in gauge theory with adjoint scalar field. The scalar field has nonminimal coupling to the gauge field, such that the scale of noncommutativity is determined by the vacuum value of the scalar field. The domain walls are solutions of the BPS equations in the theory. It is natural to interprete the domain wall as a stack of D-branes plus a stack of folded D-branes. We support this interpretation by the analysis of small fluctuations around domain walls, and suggest that such configurations of branes emerge as solutions of the Matrix model in large class of pp-wave backgrounds with inhomogeneous field strength. We point out that the folded D-brane per se provides an explicit realization of the 'mirror world' idea, and speculate on some phenomenological consequences of this scenario.
Baecklund transformations, D-branes and fluxes in minimal type 0 strings
Energy Technology Data Exchange (ETDEWEB)
Carlisle, James E [Centre for Particle Theory, Department of Mathematical Sciences, University of Durham, Durham DH1 3LE, England (United Kingdom); Johnson, Clifford V [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Pennington, Jeffrey S [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States)
2007-10-12
We study the type 0A string theory in the (2, 4k) superconformal minimal model backgrounds, focusing on the fully non-perturbative string equations which define the partition function of the model. The equations admit a parameter, {gamma}, which in the spacetime interpretation controls the number of background D-branes, or R-R flux units, depending upon which weak coupling regime is taken. We study the properties of the string equations (often focusing on the (2, 4) model in particular) and their physical solutions. The solutions are the potential for an associated Schroedinger problem whose wavefunction is that of an extended D-brane probe. We perform a numerical study of the spectrum of this system for varying {gamma} and establish that when {gamma} is a positive integer the equations' solutions have special properties consistent with the spacetime interpretation. We also show that a natural solution-generating transformation (that changes {gamma} by an integer) is the Baecklund transformation of the KdV hierarchy specialized to (scale invariant) solitons at the zero velocity. Our results suggest that the localized D-branes of the minimal string theories are directly related to the solitons of the KdV hierarchy.
D-brane gauge theories from toric singularities of the form $C^3/\\Gamma$ and $C^4/\\Gamma$
Sarkar, Tapobrata
2000-01-01
We discuss examples of D-branes probing toric singularities, and the computation of their world-volume gauge theories from the geometric data of the singularities. We consider several such examples of D-branes on partial resolutions of the orbifolds ${\\bf C^3/Z_2\\times Z_2}$,${\\bf C^3/Z_2\\times Z_3}$ and ${\\bf C^4/Z_2\\times Z_2 \\times Z_2}$.
Exact relations between M2-brane theories with and without Orientifolds
Honda, Masazumi
2015-01-01
We study partition functions of low-energy effective theories of M2-branes, whose type IIB brane constructions include orientifolds. We mainly focus on circular quiver superconformal Chern-Simons theory on S^3, whose gauge group is O(2N+1)x USp(2N)x ... x O(2N+1)x USp(2N). This theory is a natural generalization of N=5 ABJM theory with the gauge group O(2N+1)_{2k}x USp(2N)_{-k}. We find that the partition function of this type of theory has a simple relation to the one of the M2-brane theories without the orientifolds, whose gauge group is U(N)x ... x U(N). By using this relation, we determine an exact form of the grand partition function of the O(2N+1)_2 x USp(2N)_{-1} ABJM theory, where its supersymmetry is expected to enhance to N=6. As another interesting application, we discuss that our result gives a natural physical interpretation of a relation between grand partition functions of the U(N+1)_4 x U(N)_{-4} ABJ theory and U(N)_2 x U(N)_{-2} ABJM theory, recently conjectured by Grassi-Hatsuda-Marino. We a...
New N=1 dualities from orientifold transitions - Part II: String Theory
García-Etxebarria, Iñaki; Wrase, Timm
2013-01-01
We present a string theoretical description, given in terms of branes and orientifolds wrapping vanishing cycles, of the dual pairs of gauge theories analyzed in 1210.7799. Based on the resulting construction we argue that the duality that we observe in field theory is inherited from S-duality of type IIB string theory. We analyze in detail the complex cone over the zeroth del Pezzo surface and discuss an infinite family of orbifolds of flat space. For the del Pezzo case we describe the system in terms of large volume objects, and show that in this language the duality can be understood from the strongly coupled behavior of the O7^+ plane, which we analyze using simple F-theory considerations. For all cases we also give a different argument based on the existence of appropriate torsional components of the 3-form flux lattice. Along the way we clarify some aspects of the description of orientifolds in the derived category of coherent sheaves, and in particular we discuss the important role played by exotic ori...
IIB supergravity on manifolds with SU(4) structure and generalized geometry
Prins, Daniël
2013-01-01
We consider N=(2,0) backgrounds of IIB supergravity on eight-manifolds M_8 with strict SU(4) structure. We give the explicit solution to the Killing spinor equations as a set of algebraic relations between irreducible su(4) modules of the fluxes and the torsion classes of M_8. One consequence of supersymmetry is that M_8 must be complex. We show that the conjecture of arxiv:1010.5789 concerning the correpondence between background supersymmetry equations in terms of generalized pure spinors and generalized calibrations for admissible static, magnetic D-branes, does not capture the full set of supersymmetry equations. We identify the missing constraints and express them in the form of a single pure-spinor equation which is well defined for generic SU(4)\\times SU(4) backgrounds. This additional equation is given in terms of a certain analytic continuation of the generalized calibration form for codimension-2 static, magnetic D-branes.
Shift-symmetries and gauge coupling functions in orientifolds and F-theory
Corvilain, Pierre; Regalado, Diego
2016-01-01
We investigate the field dependence of the gauge coupling functions of four-dimensional Type IIB orientifold and F-theory compactifications with space-time filling seven-branes. In particular, we analyze the constraints imposed by holomorphicity and covariance under shift-symmetries of the bulk and brane axions. This requires introducing quantum corrections that necessarily contain Riemann theta functions on the complex torus spanned by the D7-brane Wilson line moduli. Our findings hint towards a new underlying geometric structure for gauge coupling functions in string compactifications. We generalize this discussion to a genuine F-theory compactification on an elliptically fibered Calabi-Yau fourfold. We perform the first general dimensional reduction of eleven-dimensional supergravity and dualization to the F-theory frame. The resulting effective action is compared with the circle reduction of a four-dimensional N=1 supergravity theory. The F-theory geometry elegantly unifies bulk and brane degrees of freed...
D-Branes, RR-Fields and Duality on Noncommutative Manifolds
Brodzki, J; Rosenberg, J; Szabó, R J; Brodzki, Jacek; Mathai, Varghese; Rosenberg, Jonathan; Szabo, Richard J.
2006-01-01
We develop some of the ingredients needed for string theory on noncommutative spacetimes, proposing an axiomatic formulation of T-duality as well as establishing a very general formula for D-brane charges. This formula is closely related to a noncommutative Grothendieck-Riemann-Roch theorem that is proved here. Our approach relies on a very general form of Poincare duality, which is studied here in detail. Among the technical tools employed are calculations with iterated products in bivariant K-theory and cyclic theory, which are simplified using a novel diagram calculus reminiscent of Feynman diagrams.
Inflation driven by single geometric tachyon with D-brane orbiting around NS5-branes
Kwon, Pyung Seong; Panigrahi, Kamal L; Sami, M
2011-01-01
We investigate models in which inflation is driven by a single geometrical tachyon. We assume that the D-brane as a probe brane in the background of NS5-branes has non-zero angular momentum which is shown to play similar role as the number of the scalar fields of the assisted inflation. We demonstrate that the angular momentum corrected effective potential allows to account for the observational constraint on COBE normalization, spectral index $n_S$ and the tensor to scalar ratio of perturbations consistent with WMAP seven years data.
Inflation driven by single geometric tachyon with D-brane orbiting around NS5-branes
Energy Technology Data Exchange (ETDEWEB)
Kwon, Pyung Seong, E-mail: bskwon@ks.ac.kr [Department of Physics, Kyungsung University, Pusan 608-736 (Korea, Republic of); Jun, Gyeong Yun, E-mail: gyjun@ks.ac.kr [Department of Physics, Kyungsung University, Pusan 608-736 (Korea, Republic of); Panigrahi, Kamal L., E-mail: panigrahi@phy.iitkgp.ernet.in [Department of Physics and Meteorology and Centre for Theoretical Studies, Indian Institute of Technology Kharagpur, 721 302 (India); Sami, M., E-mail: sami@iucaa.ernet.in [Center for Theoretical Physics, Jamia Millia Islamia, New Delhi 110092 (India)
2012-05-30
We investigate models in which inflation is driven by a single geometrical tachyon. We assume that the D-brane as a probe brane in the background of NS5-branes has non-zero angular momentum which is shown to play similar role as the number of the scalar fields of the assisted inflation. We demonstrate that the angular momentum corrected effective potential allows to account for the observational constraint on COBE normalization, spectral index n{sub S} and the tensor to scalar ratio of perturbations consistent with WMAP seven years data.
Körs, B
1999-01-01
We study nonperturbative aspects of asymmetric orbifolds of type IIA, focussing on models that allow a dual perturbative heterotic description. In particular we derive the boundary states that describe the nonsupersymmetric D-branes of the untwisted sector and their zero mode spectra. These we use to demonstrate, how some special non BPS multiplets are identified under the duality map, and give some indications, how the mismatch of bosons and fermions in the perturbative heterotic spectrum is to be interpreted in terms of the nonperturbative degrees of freedom on the type IIA side.
Orientifold Planar Equivalence: The Chiral Condensate
Armoni, A; Patella, A; Pica, C
2008-01-01
The recently introduced orientifold planar equivalence is a promising tool for solving non-perturbative problems in QCD. One of the predictions of orientifold planar equivalence is that the chiral condensates of a theory with $N_f$ flavours of Dirac fermions in the symmetric (or antisymmetric) representation and $N_f$ flavours of Majorana fermions in the adjoint representation have the same large $N$ value for any value of the mass of the (degenerate) fermions. Assuming the invariance of the theory under charge conjugation, we prove this statement on the lattice for staggered quenched condensates in SU($N$) Yang-Mills in the large $N$ limit. Then, we compute numerically those quenched condensates for $N$ up to 8. After separating the even from the odd corrections in $1/N$, we are able to show that our data support the equivalence; however, unlike other quenched observables, subleading terms in $1/N$ are needed for describing the data for the symmetric and antisymmetric representation at $N$=3. Possible lesson...
Liu, Chien-Hao
2016-01-01
In earlier works, D(1) (arXiv:0709.1515 [math.AG]), D(11.1) (arXiv:1406.0929 [math.DG]), D(11.2) (arXiv:1412.0771 [hep-th]), and D(11.3.1) (arXiv:1508.02347 [math.DG]), we have explained why a D-brane in string theory, when treated as a fundamental dynamical object, can be described by a map $\\varphi$ from an Azumaya/matrix manifold $X^{Az}$ (cf. D-brane world-volume) with a fundamental module with a connection $(E,\
Hamilton-Jacobi method and effective actions of D-brane and M-brane in supergravity
Energy Technology Data Exchange (ETDEWEB)
Sato, Matsuo E-mail: machan@het.phys.sci.osaka-u.ac.jp; Tsuchiya, Asato E-mail: tsuchiya@het.phys.sci.osaka-u.ac.jp
2003-11-03
We show that the effective actions of D-brane and M-brane are solutions to the Hamilton-Jacobi (H-J) equations in supergravities. This fact means that these effective actions are on-shell actions in supergravities. These solutions to the H-J equations reproduce the supergravity solutions that represent D-branes in a B{sub 2} field, M2 branes and the M2-M5 bound states. The effective actions in these solutions are those of a probe D-brane and a probe M-brane. Our findings can be applied to the study of the gauge/gravity correspondence, especially the holographic renormalization group, and a search for new solutions of supergravity.
Hamilton-Jacobi method and effective actions of D-brane and M-brane in supergravity
Sato, Matsuo; Tsuchiya, Asato
2003-11-01
We show that the effective actions of D-brane and M-brane are solutions to the Hamilton-Jacobi (H-J) equations in supergravities. This fact means that these effective actions are on-shell actions in supergravities. These solutions to the H-J equations reproduce the supergravity solutions that represent D-branes in a B2 field, M2 branes and the M2-M5 bound states. The effective actions in these solutions are those of a probe D-brane and a probe M-brane. Our findings can be applied to the study of the gauge/gravity correspondence, especially the holographic renormalization group, and a search for new solutions of supergravity.
Domain Walls and Flux Tubes in N=2 SQCD D-Brane Prototypes
Shifman, M
2003-01-01
This paper could have been entitled "D branes and strings from flesh and blood." We study field theoretic prototypes of D branes/strings. To this end we consider (2+1)-dimensional domain walls in (3+1)-dimensional N=2 SQCD with SU(2) gauge group and two quark flavors in the fundamental representation. This theory is perturbed by a small mass term of the adjoint matter which, in the leading order in the mass parameter, does not break N=2 supersymmetry, and reduces to a (generalized) Fayet-Iliopoulos term in the effective low-energy N=2 SQED. We find 1/2 BPS-saturated domain wall solution interpolating between two quark vacua at weak coupling, and show that this domain wall localizes a U(1) gauge field. To make contact with the brane/string picture we consider the Abrikosov-Nielsen-Olesen magnetic flux tube in one of two quark vacua and demonstrate that it can end on the domain wall. We find an explicit 1/4 BPS-saturated solution for the wall/flux tube junction. We verify that the end point of the flux tube on ...
Backlund Transformations, D-Branes, and Fluxes in Minimal Type 0 Strings
Carlisle, J E; Pennington, J S; Carlisle, James E.; Johnson, Clifford V.; Pennington, Jeffrey S.
2005-01-01
We study the Type 0A string theory in the (2,4k) superconformal minimal model backgrounds, focusing on the fully non-perturbative string equations which define the partition function of the model. The equations admit a parameter, Gamma, which in the spacetime interpretation controls the number of background D-branes, or R-R flux units, depending upon which weak coupling regime is taken. We study the properties of the string equations (often focusing on the (2,4) model in particular) and their physical solutions. The solutions are the potential for an associated Schrodinger problem whose wavefunction is that of an extended D-brane probe. We perform a numerical study of the spectrum of this system for varying Gamma and establish that when Gamma is a positive integer the equations' solutions have special properties consistent with the spacetime interpretation. We also show that a natural solution-generating transformation (that changes Gamma by an integer) is the Backlund transformation of the KdV hierarchy spec...
Nonassociative Star Product Deformations for D-Brane World-Volumes in Curved Backgrounds
Cornalba, Lorenzo; Schiappa, Ricardo
We investigate the deformation of D-brane world-volumes in curved backgrounds. We calculate the leading corrections to the boundary conformal field theory involving the background fields, and in particular we study the correlation functions of the resulting system. This allows us to obtain the world-volume deformation, identifying the open string metric and the noncommutative deformation parameter. The picture that unfolds is the following: when the gauge invariant combination ω=B+F is constant one obtains the standard Moyal deformation of the brane world-volume. Similarly, when dω= 0 one obtains the noncommutative Kontsevich deformation, physically corresponding to a curved brane in a flat background. When the background is curved, H=dω≠ 0, we find that the relevant algebraic structure is still based on the Kontsevich expansion, which now defines a nonassociative star product with an A∞ homotopy associative algebraic structure. We then recover, within this formalism, some known results of Matrix theory in curved backgrounds. In particular, we show how the effective action obtained in this framework describes, as expected, the dielectric effect of D-branes. The polarized branes are interpreted as a soliton, associated to the condensation of the brane gauge field.
Nonassociative star product deformations for D-Brane world-volumes in curved backgrounds
Energy Technology Data Exchange (ETDEWEB)
Cornalba, L. [Lab. de Physique Theorique, Ecole Normale Superieure, Paris (France); Schiappa, R. [Harvard Univ., Cambridge, MA (United States). Dept. of Physics
2002-01-01
We investigate the deformation of D-brane world-volumes in curved backgrounds. We calculate the leading corrections to the boundary conformal field theory involving the background fields, and in particular we study the correlation functions of the resulting system. This allows us to obtain the world-volume deformation, identifying the open string metric and the noncommutative deformation parameter. The picture that unfolds is the following: when the gauge invariant combination {omega}=B+F is constant one obtains the standard Moyal deformation of the brane world-volume. Similarly, when d{omega}=0 one obtains the noncommutative Kontsevich deformation, physically corresponding to a curved brane in a flat background. When the background is curved, H=d{omega}{ne}0, we find that the relevant algebraic structure is still based on the Kontsevich expansion, which now defines a nonassociative star product with an A{sub {infinity}} homotopy associative algebraic structure. We then recover, within this formalism, some known results of Matrix theory in curved backgrounds. In particular, we show how the effective action obtained in this framework describes, as expected, the dielectric effect of D-branes. The polarized branes are interpreted as a soliton, associated to the condensation of the brane gauge field. (orig.)
Liu, Chien-Hao
2014-01-01
In this Part II of D(11), we introduce new objects: super-$C^k$-schemes and Azumaya super-$C^k$-manifolds with a fundamental module (or, synonymously, matrix super-$C^k$-manifolds with a fundamental module), and extend the study in D(11.1) ([L-Y3], arXiv:1406.0929 [math.DG]) to define the notion of `differentiable maps from an Azumaya/matrix supermanifold with a fundamental module to a real manifold or supermanifold'. This allows us to introduce the notion of `fermionic D-branes' in two different styles, one parallels Ramond-Neveu-Schwarz fermionic string and the other Green-Schwarz fermionic string. A more detailed discussion on the Higgs mechanism on dynamical D-branes in our setting, taking maps from the D-brane world-volume to the space-time in question and/or sections of the Chan-Paton bundle on the D-brane world-volume as Higgs fields, is also given for the first time in the D-project. Finally note that mathematically string theory begins with the notion of a differentiable map from a string world-sheet...
The K-Theoretic Formulation of D-Brane Aharonov-Bohm Phases
Directory of Open Access Journals (Sweden)
Aaron R. Warren
2012-01-01
Full Text Available The topological calculation of Aharonov-Bohm phases associated with D-branes in the absence of a Neveu-Schwarz B-field is explored. The K-theoretic classification of Ramond-Ramond fields in Type II and Type I theories is used to produce formulae for the Aharonov-Bohm phase associated with a torsion flux. A topological construction shows that K-theoretic pairings to calculate such phases exist and are well defined. An analytic perspective is then taken, obtaining a means for determining Aharonov-Bohm phases by way of the reduced eta-invariant. This perspective is used to calculate the phase for an experiment involving the (−1 −8 system in Type I theory and compared with previous calculations performed using different methods.
Possible topological quantum computation via Khovanov homology: D-brane topological quantum computer
Vélez, Mario; Ospina, Juan
2009-05-01
A model of a D-Brane Topological Quantum Computer (DBTQC) is presented and sustained. The model is based on four-dimensional TQFTs of the Donaldson-Witten and Seiber-Witten kinds. It is argued that the DBTQC is able to compute Khovanov homology for knots, links and graphs. The DBTQC physically incorporates the mathematical process of categorification according to which the invariant polynomials for knots, links and graphs such as Jones, HOMFLY, Tutte and Bollobás-Riordan polynomials can be computed as the Euler characteristics corresponding to special homology complexes associated with knots, links and graphs. The DBTQC is conjectured as a powerful universal quantum computer in the sense that the DBTQC computes Khovanov homology which is considered like powerful that the Jones polynomial.
A Note on Dimer Models and D-brane Gauge Theories
Agarwal, Prarit; Sarkar, Tapobrata
2008-01-01
The connection between quiver gauge theories and dimer models has been well studied. It is known that the matter fields of the quiver gauge theories can be represented using the perfect matchings of the dimer model. We conjecture that the perfect matchings give information about the charge matrix of the quiver gauge theory. Further, we perform explicit computations on some aspects of partial resolutions of toric singularities using dimer models. We analyse these with graph theory techniques, using the perfect matchings of orbifolds of the form $\\BC^3/\\Gamma$, where the orbifolding group $\\Gamma$ may be noncyclic. Using these, we study the construction of the superpotential of gauge theories living on D-branes which probe these singularities, including the case where one or more adjoint fields are present upon partial resolution. Applying a combination of open and closed string techniques to dimer models, we also study some aspects of their symmetries.
D-Brane Potentials from Multi-Trace Deformations in AdS/CFT
Bernamonti, Alice
2009-01-01
It is known that certain AdS boundary conditions allow smooth initial data to evolve into a big crunch. To study this type of cosmological singularity, one can use the dual quantum field theory, where the non-standard boundary conditions are reflected by the presence of a multi-trace potential unbounded below. For specific AdS_4 and AdS_5 models, we provide a D-brane (or M-brane) interpretation of the unbounded potential. Using probe brane computations, we show that the AdS boundary conditions of interest cause spherical branes to be pushed to the boundary of AdS in finite time, and that the corresponding potential agrees with the multi-trace deformation of the dual field theory. Systems with expanding spherical D3-branes are related to big crunch supergravity solutions by a phenomenon known as geometric transition.
Musso, Daniele
2012-01-01
The non-perturbative dynamics of quantum field theories is studied using theoretical tools inspired by string formalism. Two main lines are developed: the analysis of stringy instantons in a class of four-dimensional N=2 gauge theories and the holographic study of the minimal model for a strongly coupled unbalanced superconductor. The field theory instanton calculus admits a natural and efficient description in terms of D-brane models. In addition, the string viewpoint offers the possibility of generalizing the ordinary instanton configurations. Even though such generalized, or stringy, instantons would be absent in a purely field-theoretical, low-energy treatment, we demonstrate that they do alter the IR effective description of the brane dynamics by introducing contributions related to the string scale. In the first part of this thesis we compute explicitly the stringy instanton corrections to the effective prepotential in a class of quiver gauge theories. In the second part of the thesis, we present a deta...
Testing 5d-6d dualities with fractional D-branes
Yun, Youngbin
2016-12-01
6d SCFTs compactified on a circle can often be studied from nonperturbative 5d super-Yang-Mills theories, using instanton solitons. However, the 5d Yang-Mills theories with 6d UV fixed points frequently have too many hypermultiplet matters, which makes it difficult to use the ADHM techniques for instantons. With the examples of 6d N=(1, 0) SCFTs with Sp( N) gauge symmetry and 2 N + 8 fundamental hypermultiplets, we show that one can still make rigorous studies of these 5d-6d relations in the `fractional D-brane sectors'. We test the recently proposed 5d duals given by Sp( N + 1) gauge theories, and compare their instanton partition functions with the elliptic genera of 6d self-dual strings.
D6-brane Splitting on Type IIA Orientifolds
Cvetic, M; Li, T; Liu, T; Cvetic, Mirjam; Langacker, Paul; Li, Tianjun; Liu, Tao
2004-01-01
We address both the string and field theory aspects of D6-brane splitting on Type IIA orientifolds with supersymmetric intersecting D6-branes. We focus specifically on the Z_2 x Z_2 orientifolds and address the symmetry breaking pattern for D6-branes parallel with the orientifold 6-planes as well as those positioned at angles. We demonstrate that the string theory results, which have a beautiful geometric interpretation, are in one to one correspondence with the field theory results associated with vacuum expectation values (Higgsing) of moduli in the antisymmetric representation of Sp(2N) gauge symmetry (for branes parallel with orientifold planes) or adjoint representation of U(N) (for branes at general angles). In particular, moving branes away from the orientifold planes results in change of the chiral spectrum and may change the number of families. We also provide the first new examples of the supersymmetric Standard-like models with the electroweak symmetry arising from the branes parallel with the orie...
Planar Limit of Orientifold Field Theories and Emergent Center Symmetry
Energy Technology Data Exchange (ETDEWEB)
Armoni, Adi; Shifman, Mikhail; Unsal, Mithat
2007-12-05
We consider orientifold field theories (i.e. SU(N) Yang-Mills theories with fermions in the two-index symmetric or antisymmetric representations) on R{sub 3} x S{sub 1} where the compact dimension can be either temporal or spatial. These theories are planar equivalent to supersymmetric Yang-Mills. The latter has Z{sub N} center symmetry. The famous Polyakov criterion establishing confinement-deconfinement phase transition as that from Z{sub N} symmetric to Z{sub N} broken phase applies. At the Lagrangian level the orientifold theories have at most a Z{sub 2} center. We discuss how the full Z{sub N} center symmetry dynamically emerges in the orientifold theories in the limit N {yields} {infinity}. In the confining phase the manifestation of this enhancement is the existence of stable k-strings in the large-N limit of the orientifold theories. These strings are identical to those of supersymmetric Yang-Mills theories. We argue that critical temperatures (and other features) of the confinement-deconfinement phase transition are the same in the orientifold daughters and their supersymmetric parent up to 1/N corrections. We also discuss the Abelian and non-Abelian confining regimes of four-dimensional QCD-like theories.
Non-supersymmetric Orientifolds of Gepner Models
Gato-Rivera, B
2008-01-01
Starting from a previously collected set of tachyon-free closed strings, we search for N=2 minimal model orientifold spectra which contain the standard model and are free of tachyons and tadpoles at lowest order. For each class of tachyon-free closed strings -- bulk supersymmetry, automorphism invariants or Klein bottle projection -- we do indeed find non-supersymmetric and tachyon free chiral brane configurations that contain the standard model. However, a tadpole-cancelling hidden sector could only be found in the case of bulk supersymmetry. Although about half of the examples we have found make use of branes that break the bulk space-time supersymmetry, the resulting massless open string spectra are nevertheless supersymmetric in all cases. Dropping the requirement that the standard model be contained in the spectrum, we find chiral tachyon and tadpole-free solutions in all three cases, although in the case of bulk supersymmetry all massless spectra are supersymmetric. In the other two cases we find truly ...
Dynamical Generation of mu-terms and Yukawa Couplings in Intersecting D-brane Models
Kitazawa, N
2004-01-01
We construct a supersymmetric composite model from type IIA T^6/(Z_2 x Z_2) orientifolds with intersecting D6-branes. All the three generations of quarks and leptons are naturally emerged as composite fields at low energies. Two pairs of light electroweak Higgs doublets can be obtained with realistic values of mu-terms. The hierarchical Yukawa couplings for the quark-lepton mass can be generated by the interplay between the string-level higher dimensional interactions among "preons" and the dynamics of the confinement of "preons". The model is not perfectly realistic in some points: some exotic particles, one additional U(1) gauge symmetry, no explicit mechanism for supersymmetry breaking, and so on.
Cohomological orientifold Donaldson-Thomas invariants as Chow groups
Franzen, Hans
2016-01-01
We establish a geometric interpretation of orientifold Donaldson-Thomas invariants of $\\sigma$-symmetric quivers with involution. More precisely, we prove that the cohomological orientifold Donaldson-Thomas invariant is isomorphic to the rational Chow group of the moduli space of $\\sigma$-stable self-dual quiver representations. As an application we prove that the Chow Betti numbers of moduli spaces of stable $m$-tuples in classical Lie algebras can be computed numerically. We also prove a cohomological wall-crossing formula relating semistable Hall modules for different stabilities.
LHC Phenomenology and Cosmology of String-Inspired Intersecting D-Brane Models
Anchordoqui, Luis A; Goldberg, Haim; Huang, Xing; Lust, Dieter; Taylor, Tomasz R; Vlcek, Brian
2012-01-01
We discuss the phenomenology and cosmology of a Standard-like Model inspired by string theory, in which the gauge fields are localized on D-branes wrapping certain compact cycles on an underlying geometry, whose intersection can give rise to chiral fermions. The energy scale associated with string physics is assumed to be near the Planck mass. To develop our program in the simplest way, we work within the construct of a minimal model with gauge-extended sector U (3)_B \\times Sp (1)_L \\times U (1)_{I_R} \\times U (1)_L. The resulting U (1) content gauges the baryon number B, the lepton number L, and a third additional abelian charge I_R which acts as the third isospin component of an SU(2)_R. All mixing angles and gauge couplings are fixed by rotation of the U(1) gauge fields to a basis diagonal in hypercharge Y and in an anomaly free linear combination of I_R and B-L. The anomalous $Z'$ gauge boson obtains a string scale St\\"uckelberg mass via a 4D version of the Green-Schwarz mechanism. To keep the realizatio...
Stability Of D-brane Geometries And A Quantum Check Of Ads/cft
Mitra, I
2003-01-01
The first part of this thesis explores the stability of non-supersymmetric constructions using D-branes and M- branes. Guided mainly by intuition developed using the correspondence between gauge theory and gravity, known as AdS/CFT, we propose a precise relationship between thermodynamic and dynamical stability of non-extremal branes. We verify the conjecture explicitly for non- extremal M2-branes with angular momentum in planes perpendicular to the world-volume, in the limit of many M2-branes where the supergravity approximation is reliable. Next, we explore the stability of near-horizon geometries of extremal branes which are product geometries of anti-de Sitter space and positively curved Einstein spaces. Our main motivation is to answer the question: Do non-supersymmetric stable vacua exist? We find that the answer is yes. But for Type IIA strings in the presence of D8-branes and for a non-supersymmetric open string theory with gauge group USp(32) we find that spherical compactifications are unstable. The...
Orientifolds of type IIA strings on Calabi-Yau manifolds
Govindarajan, S; Govindarajan, Suresh; Majumder, Jaydeep
2004-01-01
We identify type IIA orientifolds that are dual to M-theory compactifications on manifolds with G_2-holonomy. We then discuss the construction of crosscap states in Gepner models. (Based on a talk presented by S.G. at PASCOS 2003 held at the Tata Institute of Fundamental Research, Mumbai during Jan. 3-8, 2003.)
Implementing odd-axions in dimensional oxidation of non-geometric type IIB action
Shukla, Pramod
2016-01-01
In a setup of type IIB string compactification on an orientifold of a ${\\mathbb T}^6/{\\mathbb Z}_4$ sixfold, the presence of geometric flux ($\\omega$) and non-geometric fluxes ($Q, R$) is implemented along with the standard NS-NS and RR three-form fluxes ($H, F$). After computing the F/D-term contributions to the ${\\cal N}=1$ four dimensional effective scalar potential, we rearrange the same into `suitable' pieces by using a set of new generalized flux orbits. Subsequently, we dimensionally oxidize the various pieces of the total four dimensional scalar potential to guess their ten-dimensional origin.
Shift-symmetries and gauge coupling functions in orientifolds and F-theory
Corvilain, Pierre; Grimm, Thomas W.; Regalado, Diego
2017-05-01
We investigate the field dependence of the gauge coupling functions of four-dimensional Type IIB orientifold and F-theory compactifications with space-time filling seven-branes. In particular, we analyze the constraints imposed by holomorphicity and covariance under shift-symmetries of the bulk and brane axions. This requires introducing quantum corrections that necessarily contain Riemann theta functions on the complex torus spanned by the D7-brane Wilson line moduli. Our findings hint towards a new underlying geometric structure for gauge coupling functions in string compactifications. We generalize this discussion to a genuine F-theory compactification on an elliptically fibered Calabi-Yau fourfold. We perform the first general dimensional reduction of eleven-dimensional super-gravity and dualization to the F-theory frame. The resulting effective action is compared with the circle reduction of a four-dimensional N = 1 supergravity theory. The F-theory geometry elegantly unifies bulk and brane degrees of freedom and allows us to infer non-trivial results about holomorphicity and shift-symmetries. For instance, we gain new insight into kinetic mixing of bulk and brane gauge fields.
SU(5) orientifolds, Yukawa couplings, Stringy Instantons and Proton Decay
Kiritsis, Elias; Schellekens, Bert; 10.1016
2009-01-01
We construct a large class of SU(5) orientifold vacua with tadpole cancellation both for the standard and the flipped case. We give a general analysis of superpotential couplings up to quartic order in orientifold vacua and identify the properties of needed Yukawa couplings as well as the baryon number violating couplings. We point out that successful generation of the perturbatively forbidden Yukawa couplings entails a generically disastrous rate for proton decay from an associated quartic term in the superpotential, generated from the same instanton effects. This problem seems generic and may appear in F-theory vacua as well. We search for the appropriate instanton effects that generate the missing Yukawa couplings in the SU(5) vacua we constructed and find them in a small subset of them.
A numerical investigation of orientifold planar equivalence for quenched mesons
Lucini, Biagio; Patella, Agostino; Rago, Antonio
2010-01-01
We measure on the lattice the quenched pseudoscalar and vector meson masses at a fixed value of the lattice spacing for SU(N) gauge theory with fermions in the adjoint, in the symmetric and in the antisymmetric representations of the gauge group. Simulations are performed for N=3,4,6 in all those representations, with the addition of N=2 for the adjoint representation. We illustrate a strategy for separating the even from the odd-power contributions in 1/N in the masses. Using this technique, we extrapolate the vector mass to the large-N limit in the chiral region and show that at N = infty this mass is the same within errors in all the three representations, as predicted by orientifold planar equivalence. Possible implications of our investigation for studying orientifold planar equivalence in the dynamical case are discussed.
String Theory on Elliptic Curve Orientifolds and KR-Theory
Doran, Charles; Méndez-Diez, Stefan; Rosenberg, Jonathan
2015-04-01
We analyze the brane content and charges in all of the orientifold string theories on space-times of the form , where E is an elliptic curve with holomorphic or anti-holomorphic involution. Many of these theories involve "twistings" coming from the B-field and/or sign choices on the orientifold planes. A description of these theories from the point of view of algebraic geometry, using the Legendre normal form, naturally divides them into three groupings. The physical theories within each grouping are related to one another via sequences of T-dualities. Our approach agrees with both previous topological calculations of twisted KR-theory and known physics arguments, and explains how the twistings originate from both a mathematical and a physical perspective.
Aoki, H; Kawai, H; Kitazawa, Y; Tada, T; Tsuchiya, A
1999-01-01
We review our proposal for a constructive definition of superstring, type IIB matrix model. The IIB matrix model is a manifestly covariant model for space-time and matter which possesses N=2 supersymmetry in ten dimensions. We refine our arguments to reproduce string perturbation theory based on the loop equations. We emphasize that the space-time is dynamically determined from the eigenvalue distributions of the matrices. We also explain how matter, gauge fields and gravitation appear as fluctuations around dynamically determined space-time.
Poisson Lie symmetry and D-branes in WZW model on the Heisenberg Lie group $H_4$
Eghbali, A
2015-01-01
We show that the WZW model on the Heisenberg Lie group $H_4$ has Poisson-Lie symmetry only when the dual Lie group is ${ A}_2 \\oplus 2{ A}_1$. In this way, we construct the mutual T-dual sigma models on Drinfel'd double generated by the Heisenberg Lie group $H_4$ and its dual pair, ${ A}_2 \\oplus 2{ A}_1$, as the target space in such a way that the original model is the same as the $H_4$ WZW model. Furthermore, we show that the dual model is conformal up to two loops order. Finally, we discuss $D$-branes and the worldsheet boundary conditions defined by a gluing matrix on the $H_4$ WZW model. Using the duality map obtained from the canonical transformation description of the Poisson-Lie T-duality transformations for the gluing matrix which locally defines the properties of the $D$-brane, we find two different cases of the gluing matrices for the WZW model based on the Heisenberg Lie group $H_4$ and its dual model.
Poisson Lie symmetry and D-branes in WZW model on the Heisenberg Lie group H4
Directory of Open Access Journals (Sweden)
A. Eghbali
2015-10-01
Full Text Available We show that the WZW model on the Heisenberg Lie group H4 has Poisson–Lie symmetry only when the dual Lie group is A2⊕2A1. In this way, we construct the mutual T-dual sigma models on Drinfel'd double generated by the Heisenberg Lie group H4 and its dual pair, A2⊕2A1, as the target space in such a way that the original model is the same as the H4 WZW model. Furthermore, we show that the dual model is conformal up to two-loop order. Finally, we discuss D-branes and the worldsheet boundary conditions defined by a gluing matrix on the H4 WZW model. Using the duality map obtained from the canonical transformation description of the Poisson–Lie T-duality transformations for the gluing matrix which locally defines the properties of the D-brane, we find two different cases of the gluing matrices for the WZW model based on the Heisenberg Lie group H4 and its dual model.
D-brane gauge theories from toric singularities of the form C{sup 3}/{gamma} and C{sup 4}/{gamma}
Energy Technology Data Exchange (ETDEWEB)
Sarkar, Tapobrata E-mail: tapo@theory.tifr.res.in
2001-02-12
We discuss examples of D-branes probing toric singularities, and the computation of their world-volume gauge theories from the geometric data of the singularities. We consider several such examples of D-branes on partial resolutions of the orbifolds C{sup 3}/Z{sub 2}xZ{sub 2}, C{sup 3}/Z{sub 2}xZ{sub 3} and C{sup 4}/Z{sub 2}xZ{sub 2}xZ{sub 2}.
Deforming D-brane models on $T^6/(\\mathbb{Z}_2 \\times \\mathbb{Z}_{2M})$ orbifolds
Koltermann, Isabel; Honecker, Gabriele
2015-01-01
We review the stabilisation of complex structure moduli in Type IIA orientifolds, especially on $T^6 / (\\mathbb{Z}_2 \\times \\mathbb{Z}_6^\\prime \\times \\Omega \\mathcal{R})$ with discrete torsion, via deformations of $\\mathbb{Z}_2 \\times \\mathbb{Z}_2$ orbifold singularities. While D6-branes in SO(2N) and USp(2N) models always preserve supersymmetry and thus give rise to flat directions, in an exemplary Pati-Salam model with only U(N) gauge groups ten out of the 15 deformation moduli can be stabilised at the orbifold point.
Line bundle twisted chiral de Rham complex and bound states of D-branes on toric manifolds
Energy Technology Data Exchange (ETDEWEB)
Parkhomenko, S.E., E-mail: spark@itp.ac.ru [Landau Institute for Theoretical Physics, 142432 Chernogolovka, Moscow region (Russian Federation); Moscow Institute of Physics and Technology, 141707 Dolgoprudny, Moscow region (Russian Federation)
2014-04-15
In this note we calculate elliptic genus in various examples of twisted chiral de Rham complex on two-dimensional toric compact manifolds and Calabi–Yau hypersurfaces in toric manifolds. At first the elliptic genus is calculated for the line bundle twisted chiral de Rham complex on a compact smooth toric manifold and K3 hypersurface in P{sup 3}. Then we twist chiral de Rham complex by sheaves localized on positive codimension submanifolds in P{sup 2} and calculate in each case the elliptic genus. In the last example the elliptic genus of chiral de Rham complex on P{sup 2} twisted by SL(N) vector bundle with instanton number k is calculated. In all the cases considered we find the infinite tower of open string oscillator contributions and identify directly the open string boundary conditions of the corresponding bound state of D-branes.
S-duality in N = 1 orientifold SCFTs
Energy Technology Data Exchange (ETDEWEB)
Garcia-Etxebarria, Inaki [Max Planck Institute for Physics, Munich (Germany); Heidenreich, Ben [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada)
2017-03-15
We present a general solution to the problem of determining all S-dual descriptions for a specific (but very rich) class of N = 1 SCFTs. These SCFTs are indexed by decorated toric diagrams, and can be engineered in string theory by probing orientifolds of isolated toric singularities with D3 branes. The S-dual phases are described by quiver gauge theories coupled to specific types of conformal matter which we describe explicitly. We illustrate our construction with many examples, including S-dualities in previously unknown SCFTs. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Orientifold ABJM Matrix Model: Chiral Projections and Worldsheet Instantons
Moriyama, Sanefumi
2016-01-01
We study the partition function of the orientifold ABJM theory, which is a superconformal Chern-Simons theory associated with the orthosymplectic supergroup. We find that the partition function associated with any orthosymplectic supergroup can be realized as that of a Fermi gas system whose density matrix is identical to that associated with the corresponding unitary supergroup with a projection to the even or odd chirality. Furthermore we propose an identity and use it to identify all of the Gopakumar-Vafa invariants for the worldsheet instanton effects systematically.
On de Sitter vacua in type IIA orientifold compactifications
Energy Technology Data Exchange (ETDEWEB)
Saueressig, Frank [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands)]. E-mail: f.s.saueressig@phys.uu.nl; Theis, Ulrich [Institute for Theoretical Physics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, D-07743 Jena (Germany)]. E-mail: ulrich.theis@uni-jena.de; Vandoren, Stefan [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands)]. E-mail: s.vandoren@phys.uu.nl
2006-02-02
This Letter discusses the orientifold projection of the quantum corrections to type IIA strings compactified on rigid Calabi-Yau threefolds. It is shown that N=2 membrane instanton effects give a holomorphic contribution to the superpotential, while the perturbative corrections enter into the Kahler potential. At the level of the scalar potential the corrections to the Kahler potential give rise to a positive energy contribution similar to adding anti-D3-branes in the KKLT scenario. This provides a natural mechanism to lift an AdS vacuum to a meta-stable dS vacuum.
Discrete Gauge Symmetries in Discrete MSSM-like Orientifolds
Ibanez, L E; Uranga, A M
2012-01-01
Motivated by the necessity of discrete Z_N symmetries in the MSSM to insure baryon stability, we study the origin of discrete gauge symmetries from open string sector U(1)'s in orientifolds based on rational conformal field theory. By means of an explicit construction, we find an integral basis for the couplings of axions and U(1) factors for all simple current MIPFs and orientifolds of all 168 Gepner models, a total of 32990 distinct cases. We discuss how the presence of discrete symmetries surviving as a subgroup of broken U(1)'s can be derived using this basis. We apply this procedure to models with MSSM chiral spectrum, concretely to all known U(3)xU(2)xU(1)xU(1) and U(3)xSp(2)xU(1)xU(1) configurations with chiral bi-fundamentals, but no chiral tensors, as well as some SU(5) GUT models. We find examples of models with Z_2 (R-parity) and Z_3 symmetries that forbid certain B and/or L violating MSSM couplings. Their presence is however relatively rare, at the level of a few percent of all cases.
Discrete gauge symmetries in discrete MSSM-like orientifolds
Ibáñez, L. E.; Schellekens, A. N.; Uranga, A. M.
2012-12-01
Motivated by the necessity of discrete ZN symmetries in the MSSM to insure baryon stability, we study the origin of discrete gauge symmetries from open string sector U(1)'s in orientifolds based on rational conformal field theory. By means of an explicit construction, we find an integral basis for the couplings of axions and U(1) factors for all simple current MIPFs and orientifolds of all 168 Gepner models, a total of 32 990 distinct cases. We discuss how the presence of discrete symmetries surviving as a subgroup of broken U(1)'s can be derived using this basis. We apply this procedure to models with MSSM chiral spectrum, concretely to all known U(3)×U(2)×U(1)×U(1) and U(3)×Sp(2)×U(1)×U(1) configurations with chiral bi-fundamentals, but no chiral tensors, as well as some SU(5) GUT models. We find examples of models with Z2 (R-parity) and Z3 symmetries that forbid certain B and/or L violating MSSM couplings. Their presence is however relatively rare, at the level of a few percent of all cases.
Real bundle gerbes, orientifolds and twisted KR-homology
Hekmati, Pedram; Szabo, Richard J; Vozzo, Raymond F
2016-01-01
We introduce a notion of Real bundle gerbes on manifolds equipped with an involution. We elucidate their relation to Jandl gerbes and prove that they are classified by their Real Dixmier-Douady class in Grothendieck's equivariant sheaf cohomology. We show that the Grothendieck group of Real bundle gerbe modules is isomorphic to twisted KR-theory for a torsion Real Dixmier-Douady class. Building on the Baum-Douglas model for K-homology and the orientifold construction in string theory, we introduce geometric cycles for twisted KR-homology groups using Real bundle gerbe modules. We prove that this defines a real-oriented generalised homology theory dual to twisted KR-theory for Real closed manifolds, and more generally for Real finite CW-complexes, for any Real Dixmier-Douady class. This is achieved by defining an explicit natural transformation to analytic twisted KR-homology and proving that it is an isomorphism. Our constructions give a new framework for the classification of orientifolds in string theory, p...
Kitazawa, Y; Saito, O; Kitazawa, Yoshihisa; Mizoguchi, Shun'ya; Saito, Osamu
2006-01-01
We study the zero-dimensional reduced model of D=6 pure super Yang-Mills theory and argue that the large N limit describes the (2,0) Little String Theory. The one-loop effective action shows that the force exerted between two diagonal blocks of matrices behaves as 1/r^4, implying a six-dimensional spacetime. We also observe that it is due to non-gravitational interactions. We construct wave functions and vertex operators which realize the D=6, (2,0) tensor representation. We also comment on other "little" analogues of the IIB matrix model and Matrix Theory with less supercharges.
Real Baum-Connes assembly and T-duality for torus orientifolds
Rosenberg, Jonathan
2015-03-01
We show that the real Baum-Connes conjecture for abelian groups, possibly twisted by a cocycle, explains the isomorphisms of (twisted) KR-groups that underlie all T-dualities of torus orientifold string theories.
Gran, U; Papadopoulos, G; Roest, D
2007-01-01
We adapt the spinorial geometry method to investigate supergravity backgrounds with near maximal number of supersymmetries. We then apply the formalism to show that the IIB supergravity backgrounds with 31 supersymmetries preserve an additional supersymmetry and so they are maximally supersymmetric. This rules out the existence of IIB supergravity preons.
Supersymmetric 4D Orientifolds of Type IIA with D6-branes at Angles
Blumenhagen, R; Körs, B; Blumenhagen, Ralph; Goerlich, Lars; Kors, Boris
2000-01-01
We study a certain class of four-dimensional N=1 supersymmetric orientifolds for which the world-sheet parity transformation is combined with a complex conjugation in the compact directions. We investigate in detail the orientifolds of the Z_3, Z_4, Z_6 and Z_6' toroidal orbifolds finding solutions to the tadpole cancellation conditions for all models. Generically, all the massless spectra turn out to be non-chiral.
M5-branes, orientifolds, and S-duality
Hwang, Yoonseok; Kim, Seok
2016-01-01
We study the instanton partition functions of 5d maximal super Yang-Mills theories with all classical gauge groups. They are computed from the ADHM quantum mechanics of the D0-D4-O4 systems. Our partition functions respect S-dualities of the circle compactified Yang-Mills theories and various orientifold backgrounds. We also compute and study the $S^5$ partition functions that correspond to the 6d (2,0) superconformal indices. Our SO(2N) index takes the form of the vacuum character of $\\mathcal{W}_D$ algebra in a special limit, supporting the $\\mathcal{W}$ algebra conjecture. We propose new indices for (2,0) theories with outer automorphism twists along the temporal circle, obtained from non-simply-laced SYMs on $S^5$.
M5-branes, orientifolds, and S-duality
Hwang, Yoonseok; Kim, Joonho; Kim, Seok
2016-12-01
We study the instanton partition functions of 5d maximal super Yang-Mills theories with all classical gauge groups. They are computed from the ADHM quantum mechanics of the D0-D4-O4 systems. Our partition functions respect S-dualities of the circle compactified Yang-Mills theories and various orientifold backgrounds. We also compute and study the S 5 partition functions that correspond to the 6d (2 , 0) superconformal indices. Our SO(2 N ) index takes the form of the vacuum character of W_D algebra in a special limit, supporting the W algebra conjecture. We propose new indices for (2 , 0) theories with outer automorphism twists along the temporal circle, obtained from non-simply-laced SYMs on S 5.
Natural inflation with and without modulations in type IIB string theory
Abe, Hiroyuki; Otsuka, Hajime
2014-01-01
We propose a mechanism for the natural inflation with and without modulation in the framework of type IIB string theory on toroidal orientifold or orbifold. We explicitly construct the stabilization potential of complex structure, dilaton and K\\"ahler moduli, where one of the imaginary component of complex structure moduli becomes light which is identified as the inflaton. The inflaton potential is generated by the gaugino-condensation term which receives the one-loop threshold corrections determined by the field value of complex structure moduli and the axion decay constant of inflaton is enhanced by the inverse of one-loop factor. We also find the threshold corrections can also induce the modulations to the original scalar potential for the natural inflation. Depending on these modulations, we can predict several sizes of tensor-to-scalar ratio as well as the other cosmological observables reported by WMAP, Planck and/or BICEP2 collaborations.
Dimensional oxidation and modular completion of non-geometric type IIB action
Gao, Xin
2015-01-01
Utilizing a setup of type IIB superstring theory compactified on an orientifold of T^6/(Z2 x Z2), we propose a modular invariant dimensional oxidation of the four-dimensional scalar potential. In the oxidized ten-dimensional supergravity action, the standard NS-NS and RR three form fluxes (H-, F-) as well as the non-geometric fluxes (Q-, P-) are found to nicely rearrange themselves to form generalized flux-combinations. As an application towards moduli stabilization, using the same S-duality invariant scalar potential, we examine the recently proposed No-Go theorem (in arXiv:1409.7075) about creating a mass-hierarchy between universal-axion and the dilaton relevant for axionic-inflation. We find the No-Go arguments to be quite robust even with the inclusion of non-geometric (Q-, P-) fluxes.
Type IIA orientifolds on SU(2)-structure manifolds
Energy Technology Data Exchange (ETDEWEB)
Danckaert, Thomas
2010-11-15
We investigate the possible supersymmetry-preserving orientifold projections of type IIA string theory on a six-dimensional background with SU(2)-structure. We find two categories of projections which preserve half of the low-energy supersymmetry, reducing the effective theory from an N=4 supergravity theory, to an N=2 supergravity. For these two cases, we impose the projection on the low-energy spectrum and reduce the effective N=4 supergravity action accordingly. We can identify the resulting gauged N=2 supergravity theory and bring the action into canonical form. We compute the scalar moduli spaces and characterize the gauged symmetries in terms of the geometry of these moduli spaces. Due to their origin in N=4 supergravity, which is a highly constrained theory, the moduli spaces are of a very simple form. We find that, for suitable background manifolds, isometries in all scalar sectors can become gauged. The obtained gaugings share many features with those of N=2 supergravities obtained previously from other G-structure compactifications. (orig.)
Standard Model Compactifications of IIA Z3 x Z3 Orientifolds from Intersecting D6-branes
Kokorelis, C E
2004-01-01
We discuss the construction of chiral four dimensional T^6/(Z3 x Z3) orientifold compactifications of IIA theory, using D6-branes intersecting at angles and not aligned with the orientifold O6 planes. Cancellation of mixed U(1) anomalies requires the presence of a generalized Green-Schwarz mechanism mediated by RR partners of closed string untwisted moduli. As expected all complex moduli fields get stabilized naturally in these constructions by the orbifold symmetry. In this respect we describe the appearance of three quark and lepton family SU(3)_C x SU(2)_L x U(1)_Y non-supersymmetric orientifold models with only the massless spectrum of the SM at low energy that can have either no exotics present and three families of $\
Management of type IIb dyslipidemia.
Arai, Hidenori; Ishibashi, Shun; Bujo, Hideaki; Hayashi, Toshio; Yokoyama, Shinji; Oikawa, Shinichi; Kobayashi, Junji; Shirai, Kohji; Ota, Takao; Yamashita, Shizuya; Gotoda, Takanari; Harada-Shiba, Mariko; Sone, Hirohito; Eto, Masaaki; Suzuki, Hiroaki; Yamada, Nobuhiro
2012-01-01
Although the Japan Atherosclerosis Society guideline for the diagnosis and prevention of atherosclerosis cardiovascular diseases for the Japanese population provides targets for low-density lipoprotein (LDL) cholesterol, triglycerides, and high-density lipoprotein (HDL) cholesterol to prevent cardiovascular disease in patients with dyslipidemia, there is no guideline specifically targeting the treatment of type IIb dyslipidemia, which is one of the most common types of dyslipidemia, along with type IIa and type IV dyslipidemia. Type IIb dyslipidemia is important because it sometimes accompanies atherogenic lipid profiles, such as small, dense LDL, remnants, low HDL cholesterolemia. It is also associated with type 2 diabetes mellitus, metabolic syndrome, and chronic kidney disease (CKD), and most patients with familial combined hyperlipidemia (FCHL) show this phenotype; therefore, it is assumed that patients with type IIb dyslipidemia have a high risk for cardiovascular disease. Thus, the management of type IIb dyslipidemia is very important for the prevention of cardiovascular disease, so we have attempted to provide a guideline for the management of type IIb dyslipidemia.
Self-dual quiver moduli and orientifold Donaldson-Thomas invariants
Young, Matthew B
2014-01-01
Motivated by the counting of BPS states in string theory with orientifolds, we study moduli spaces of self-dual representations of a quiver with contravariant involution. We develop Hall module techniques to compute the number of points over finite fields in moduli stacks of semistable self-dual representations. Wall-crossing formulas relate these counts for different choices of stability conditions. In particular cases, these formulas model the primitive wall-crossing of orientifold Donaldson-Thomas/BPS invariants suggested in the physics literature. In finite type examples, the wall-crossing can be understood as identities for quantum dilogarithms acting in representations of quantum tori.
Hayasaka, K; Hayasaka, Kiyoshi; Nakayama, Ryuichi
2002-01-01
We point out that when a D-brane is placed in an NS-NS B field background with non-vanishing field strength (H=dB) along the D-brane worldvolume, the coordinate of one end of the open string does not commute with that of the other in the low energy limit. The degrees of the freedom associated with both ends are not decoupled and accordingly, the effective action must be quite different from that of the ordinary noncommutative gauge theory for a constant B background. We construct an associative and noncommutative product which operates on the coordinates of both ends of the string and propose a new type of noncommutative gauge action for the low energy effective theory of a Dp-brane. This effective theory is bi-local and lives in twice as large dimensions (2D=2(p+1)) as in the H=0 case. When viewed as a theory in the D-dimensional space, this theory is non-local and we must force the two ends of the string to coincide. We will then propose a prescription for reducing this bi-local effective action to that in ...
Lee, Taejin
2016-01-01
We construct a covariant open bosonic string field theory on multiple D-branes, which reduces to a non-Abelian group Yang-Mills gauge theory in the zero-slope limit. Making use of the first quantized open bosonic string in the proper time gauge, we convert the string amplitudes given by the Polyakov path integrals on string world sheets into those of the second quantized theory. On multiple D-branes, the string field takes values in the Lie-algebra of $U(N)$ group and the three-string vertex function must be invariant under the global $U(N)$ transformation. This requirement together with the condition that the string field theory reduces to the non-Abelian gauge field theory in the zero-slope limit, uniquely determines the three-string vertex function. We also examine the effective four-string vertex diagrams generated perturbatively by the three-string vertex at tree level. In the zero-slope limit they reduce to the tree diagrams with four external gauge fields with an intermediate massless gauge field propa...
Liu, Chien-Hao
2009-01-01
In this continuation of [L-Y1], [L-L-S-Y], [L-Y2], and [L-Y3] (arXiv:0709.1515 [math.AG], arXiv:0809.2121 [math.AG], arXiv:0901.0342 [math.AG], arXiv:0907.0268 [math.AG]), we study D-branes in a target-space with a fixed $B$-field background $(Y,\\alpha_B)$ along the line of the Polchinski-Grothendieck Ansatz, explained in [L-Y1] and further extended in the current work. We focus first on the gauge-field-twist effect of $B$-field to the Chan-Paton module on D-branes. Basic properties of the moduli space of D-branes, as morphisms from Azumaya schemes with a twisted fundamental module to $(Y,\\alpha_B)$, are given. For holomorphic D-strings, we prove a valuation-criterion property of this moduli space. The setting is then extended to take into account also the deformation-quantization-type noncommutative geometry effect of $B$-field to both the D-brane world-volume and the superstring target-space(-time) $Y$. This brings the notion of twisted ${\\cal D}$-modules that are realizable as twisted locally-free coherent...
Algebraic K-theory and derived equivalences suggested by T-duality for torus orientifolds
Rosenberg, Jonathan
2016-01-01
We show that certain isomorphisms of (twisted) KR-groups that underlie T-dualities of torus orientifold string theories have purely algebraic analogues in terms of algebraic K-theory of real varieties and equivalences of derived categories of (twisted) coherent sheaves. The most interesting conclusion is a kind of Mukai duality in which the "dual abelian variety" to a smooth projective genus-1 curve over R with no real points is (mildly) noncommutative.
Deforming D-brane models on T{sup 6}/(Z{sub 2} x Z{sub 2M}) orbifolds
Energy Technology Data Exchange (ETDEWEB)
Koltermann, Isabel; Blaszczyk, Michael; Honecker, Gabriele [PRISMA Cluster of Excellence and Institut fuer Physik (WA THEP), Johannes-Gutenberg-Universitaet, Mainz (Germany)
2016-04-15
We review the stabilisation of complex structure moduli in Type IIA orientifolds, especially on T{sup 6}/(Z{sub 2} x Z{sub 6}{sup '} x ΩR) with discrete torsion, via deformations of Z{sub 2} x Z{sub 2} orbifold singularities. While D6-branes in SO(2N) and USp(2N) models always preserve supersymmetry and thus give rise to flat directions, in an exemplary Pati-Salam model with only U(N) gauge groups ten out of the 15 deformation moduli can be stabilised at the orbifold point. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Denef, Frederik; Padi, Megha
2009-01-01
By T-dualizing space-filling D-branes in IIB orientifold compactifications along the three non-internal spatial directions, we obtain black hole bound states living in a universe with a gauged spatial reflection symmetry. We call these objects orientiholes. The gravitational entropy of various IIA orientihole configurations provides an "experimental" estimate of the number of vacua in various sectors of the IIB landscape. Furthermore, basic physical properties of orientiholes map to (sometimes subtle) microscopic features, thus providing a useful alternative viewpoint on a number of issues arising in D-brane model building. More generally, we give orientihole generalizations of recently derived wall crossing formulae, and conjecture a relation to the topological string analogous to the OSV conjecture, but with a linear rather than a quadratic identification of partition functions.
The type IIB string axiverse and its low-energy phenomenology
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); INFN, Sezione di Trieste (Italy); Goodsell, Mark D. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-06-15
We study closed string axions in type IIB orientifold compactifications. We show that for natural values of the background fluxes the moduli stabilisation mechanism of the LARGE Volume Scenario (LVS) gives rise to an axiverse characterised by the presence of a QCD axion plus many light axion-like particles whose masses are logarithmically hierarchical. We study the phenomenological features of the LVS axiverse, deriving the masses of the axions and their couplings to matter and gauge fields. We also determine when closed string axions can solve the strong CP problem, and analyse the first explicit examples of semi-realistic models with stable moduli and a QCD axion candidate which is not eaten by an anomalous Abelian gauge boson. We discuss the impact of the choice of inflationary scenario on the LVS axiverse, and summarise the astrophysical, cosmological and experimental constraints upon it. Moreover, we show how models can be constructed with additional light axion-like particles that could explain some intriguing astrophysical anomalies, and could be searched for in the next generation of axion helioscopes and light-shining-through-a-wall experiments.
Predictions for orientifold field theories from type 0{sup '} string theory
Energy Technology Data Exchange (ETDEWEB)
Armoni, Adi [Department of Physics, University of Wales Swansea, Singleton Park, Swansea SA2 8PP (United Kingdom); Imeroni, Emiliano [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Postbus 80.195, 3508 TD Utrecht (Netherlands)]. E-mail: e.imeroni@phys.uu.nl
2005-12-29
Two predictions about finite-N non-supersymmetric 'orientifold field theories' are made by using the dual type 0{sup '} string theory on C{sup 3}/Z{sub 2}xZ{sub 2} orbifold singularity. First, the mass ratio between the lowest pseudoscalar and scalar color-singlets is estimated to be equal to the ratio between the axial anomaly and the scale anomaly at strong coupling, M{sub -}/M{sub +}{approx}C{sub -}/C{sub +}. Second, the ratio between the domain wall tension and the value of the quark condensate is computed.
A Three-Family Standard-like Orientifold Model Yukawa Couplings and Hierarchy
Cvetic, M; Shiu, G; Cvetic, Mirjam; Langacker, Paul; Shiu, Gary
2002-01-01
We discuss the hierarchy of Yukawa couplings in a supersymmetric three family Standard-like string Model. The model is constructed by compactifying Type IIA string theory on a Z_2 x Z_2 orientifold in which the Standard Model matter fields arise from intersecting D6-branes. When lifted to M theory, the model amounts to compactification of M-theory on a G_2 manifold. While the actual fermion masses depend on the vacuum expectation values of the multiple Higgs fields in the model, we calculate the leading worldsheet instanton contributions to the Yukawa couplings and examine the implications of the Yukawa hierarchy.
Composite inflation from super Yang-Mills theory, orientifold, and one-flavor QCD
DEFF Research Database (Denmark)
Channuie, P.; Jorgensen, J. J.; Sannino, F.
2012-01-01
Recent investigations have shown that inflation can be driven by four-dimensional strongly interacting theories nonminimally coupled to gravity. We explore this paradigm further by considering composite inflation driven by orientifold field theories. The advantage of using these theories resides ...... nonminimally coupled QCD theory of inflation. The scale of composite inflation, for all the models presented here, is of the order of 10(16) GeV. Unitarity studies of the inflaton scattering suggest that the cutoff of the model is at the Planck scale. DOI: 10.1103/PhysRevD.86.125035...
Covariant action for type IIB supergravity
Sen, Ashoke
2016-07-01
Taking clues from the recent construction of the covariant action for type II and heterotic string field theories, we construct a manifestly Lorentz covariant action for type IIB supergravity, and discuss its gauge fixing maintaining manifest Lorentz invariance. The action contains a (non-gravitating) free 4-form field besides the usual fields of type IIB supergravity. This free field, being completely decoupled from the interacting sector, has no physical consequence.
A D-brane inspired U(3){sub C}xU(3){sub L}xU(3){sub R} model
Energy Technology Data Exchange (ETDEWEB)
Leontaris, G.K. [Theoretical Physics Division, Ioannina University, GR-45110 Ioannina (Greece)]. E-mail: leonta@artemis1.physics.uoi.gr; Rizos, J. [Theoretical Physics Division, Ioannina University, GR-45110 Ioannina (Greece)
2006-01-26
Motivated by D-brane scenarios, we consider a non-supersymmetric model based on the gauge symmetry U(3){sub C}xU(3){sub L}xU(3){sub R} which is equivalent to the SU(3){sup 3} ''trinification'' model supplemented by three U(1)'s. Two U(1) combinations are anomalous while the third U(1){sub Z{sup '}} is anomaly free and contributes to the hypercharge generator. This hypercharge embedding corresponds to sin{sup 2}{theta}{sub W}=619 in the case of full gauge coupling unification. The U(3){sup 3} symmetry is broken down to the Standard Model by vevs of two (1,3,3-bar )-scalar multiplets supplemented by two Higgs fields in (1,3,1) and (1,1,3) representations. The latter break U(1){sub Z{sup '}} and provide heavy masses to the extra lepton doublets. Fermions belong to (3,3-bar ,1)+(3-bar ,1,3)+(1,3,3-bar ) representations as in the trinification model. The model predicts a natural quark-lepton hierarchy, since quark masses are obtained from tree-level couplings, while charged leptons receive masses from fourth order Yukawa terms, as a consequence of the extra Abelian symmetries. Light Majorana neutrino masses are obtained through a see-saw type mechanism operative at the SU(3){sub R} breaking scale of the order M{sub R}>=10{sup 9} GeV.
Heterotic and type II orientifold compactifications on SU(3) structure manifolds
Energy Technology Data Exchange (ETDEWEB)
Benmachiche, I.
2006-07-15
We study the four-dimensional N=1 effective theories of generic SU(3) structure compactifications in the presence of background fluxes. For heterotic and type IIA/B orientifold theories, the N=1 characteristic data are determined by a Kaluza-Klein reduction of the fermionic actions. The Kaehler potentials, superpotentials and the D-terms are entirely encoded by geometrical data of the internal manifold. The background flux and the intrinsic torsion of the SU(3) structure manifold, gives rise to contributions to the four-dimensional F-terms. The corresponding superpotentials generalize the Gukov-Vafa-Witten superpotential. For the heterotic compactification, the four-dimensional fermionic supersymmetry variations, as well as the conditions on supersymmetric vacua, are determined. The Yukawa couplings of the theory turn out to be similar to their Calabi-Yau counterparts. (Orig.)
On the exact open-closed vertex in plane-wave light-cone string field theory
Lucietti, J; Sinha, A K; Lucietti, James; Schafer-Nameki, Sakura; Sinha, Aninda
2003-01-01
The open-closed vertex in the maximally supersymmetric type IIB plane-wave light-cone string field theory is considered and an explicit solution for the bosonic part of the vertex is derived, valid for all values of the mass parameter, \\mu. This vertex is of relevance to IIB plane-wave orientifolds, as well as IIB plane-wave strings in the presence of D-branes, and their gauge theory duals. Methods of complex analysis are used to develop a systematic procedure for obtaining the solution. This procedure is first applied to the vertex in flat space, and then extended to the plane-wave case. The plane-wave solution for the vertex requires introducing certain ``\\mu-deformed Gamma functions'', which are generalizations of the ordinary Gamma function. The behaviour of the Neumann matrices is graphically illustrated and their large-\\mu asymptotics are analysed.
Generalized N=1 and N=2 structures in M-theory and type II orientifolds
Graña, Mariana
2012-01-01
We consider M-theory and type IIA reductions to four dimensions with N=2 and N=1 supersymmetry and discuss their interconnection. Our work is based on the framework of Exceptional Generalized Geometry (EGG), which extends the tangent bundle to include all symmetries in M-theory and type II string theory, covariantizing the local U-duality group E7. We describe general N=1 and N=2 reductions in terms of SU(7) and SU(6) structures on this bundle and thereby derive the effective four-dimensional N=1 and N=2 couplings, in particular we compute the Kahler and hyper-Kahler potentials as well as the triplet of Killing prepotentials (or the superpotential in the N=1 case). These structures and couplings can be described in terms of forms on an eight-dimensional tangent space where SL(8) contained in E7 acts, which might indicate a description in terms of an eight-dimensional internal space, similar to F-theory. We finally discuss an orbifold action in M-theory and its reduction to O6 orientifolds, and show how the pr...
String coupling and interactions in type IIB matrix model
Kitazawa, Yoshihisa
2008-01-01
We investigate the interactions of closed strings in IIB matrix model. The basic interaction of the closed superstring is realized by the recombination of two intersecting strings. Such interaction is investigated in IIB matrix model via two dimensional noncommutative gauge theory in the IR limit. By estimating the probability of the recombination, we identify the string coupling g_s in IIB matrix model. We confirm that our identification is consistent with matrix string theory.
Muneer, Bushra; Lali, Tayyaba; Iqbal, Muhammad J; Shakoori, Farah R; Shakoori, Abdul R
2016-10-01
Four arsenic resistant yeast were isolated from the industrial wastewater. Two strains IIB-As1 and IIB-As2 identified as Candida tropicalis and Saccharomyces cerevisiae, respectively. IIB-As1 and IIB-As2 showed maximum arsenic resistance. IIB-As1 showed maximum growth at 35 °C whereas it was 30 °C for IIB-As2. The yeast isolate showed typical growth curves, but arsenic extended the lag phase. Glutathione plays an important role in metal tolerance. In the present study, As increased the level glutathione and non-protein thiols in yeast isolates. Removal of As from supernatant was analyzed using the atomic absorption spectrophotometer. They removed arsenic from the medium after 72 h of incubation. Both yeast strains efficiently removed arsenic from the industrial effluent when used individually or in consortia. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Multiwavelength observations of the Type IIb supernova 2009mg
DEFF Research Database (Denmark)
Oates, S. R.; Bayless, A. J.; Stritzinger, M. D.
2012-01-01
We present Swift Ultra-Violet Optical Telescope and X-Ray Telescope (XRT) observations, and visual wavelength spectroscopy of the Type IIb supernova (SN) 2009mg, discovered in the Sb galaxy ESO 121-G26. The observational properties of SN 2009mg are compared to the prototype Type IIb SNe 1993J...
Multiwavelength observations of the Type IIb supernova 2009mg
DEFF Research Database (Denmark)
Oates, S. R.; Bayless, A. J.; Stritzinger, M. D.
2012-01-01
We present Swift Ultra-Violet Optical Telescope and X-Ray Telescope (XRT) observations, and visual wavelength spectroscopy of the Type IIb supernova (SN) 2009mg, discovered in the Sb galaxy ESO 121-G26. The observational properties of SN 2009mg are compared to the prototype Type IIb SNe 1993J...
Is inflation from unwinding fluxes IIB?
Gautason, Fridrik Freyr; Schillo, Marjorie; Van Riet, Thomas
2017-03-01
In this paper we argue that the mechanism of unwinding inflation is naturally present in warped compactifications of type IIB string theory with local throats. The unwinding of flux is caused by its annihilation against branes. The resulting inflaton potential is linear with periodic modulations. We initiate an analysis of the inflationary dynamics and cosmological observables, which are highly constrained by moduli stabilization. For the simplified model of single-Kähler Calabi-Yau spaces we find that many, though not all of the consistency constraints can be satisfied. Particularly, in this simple model geometric constraints are in tension with obtaining the observed amplitude of the scalar power spectrum. However, we do find 60 efolds of inflation with a trans-Planckian field excursion which offers the hope that slightly more complicated models can lead to a fully consistent explicit construction of large field inflation of this kind.
Is inflation from unwinding fluxes IIB?
Gautason, Fridrik Freyr; Van Riet, Thomas
2016-01-01
In this paper we argue that the mechanism of unwinding inflation is naturally present in warped compactifications of type IIB string theory with local throats. The unwinding of flux is caused by its annihilation against branes. The resulting inflaton potential is linear with periodic modulations. We initiate an analysis of the inflationary dynamics and cosmological observables, which are highly constrained by moduli stabilization. For the simplified model of single-K\\"ahler Calabi-Yau spaces we find that many, though not all of the consistency constraints can be satisfied. Particularly, in this simple model geometric constraints are in tension with obtaining the observed amplitude of the scalar power spectrum. However, we do find 60 efolds of inflation with a trans-Planckian field excursion which offers the hope that slightly more complicated models can lead to a fully consistent explicit construction of large field inflation of this kind.
The CDF Run IIb silicon detector
Energy Technology Data Exchange (ETDEWEB)
Aoki, M.; Bacchetta, N.; Behari, S.; Benjamin, D.; Bisello, D.; Bolla, G.; Bortoletto, D.; Burghard, A.; Busetto, G.; Cabrera, S.; Canepa, A.; Castro, A.; Cardoso, G.; Chertok, M.; Ciobanu, C.; Derylo, G.; Fang, I.; Flaugher, B. E-mail: brenna@fnal.gov; Freeman, J.; Galtieri, L.; Galyardt, J.; Garcia-Sciveres, M.; Giurgiu, G.; Gorelov, I.; Haber, C.; Hara, K.; Hoeferkamp, M.; Holbrook, B.; Hrycyk, M.; Junk, T.; Kim, S.; Kobayashi, K.; Krieger, B.; Kruse, M.; Lander, R.; Lu, R.-S.; Lukens, P.; Malferrari, L.; Manea, C.; Margotti, A.; Maksimovic, P.; Merkel, P.; Moccia, S.; Nakano, I.; Naoumov, D.; Novak, J.; Okusawa, T.; Orlov, Y.; Pancaldi, G.; Pantano, D.; Pavlicek, V.; Pellett, D.; Seidel, S.; Semeria, F.; Takei, Y.; Tanaka, R.; Wang, Z.; Watje, P.; Weber, M.; Wester, W.; Wilkes, T.; Yamamoto, K.; Yao, W.; Zimmermann, S.; Zucchelli, S.; Zucchini, A
2004-02-01
Fermilab plans to deliver 5-15 fb{sup -1} of integrated luminosity to the CDF and D0 experiments. The current inner silicon detectors at CDF (SVXIIa and L00) will not tolerate the radiation dose associated with high-luminosity running and will need to be replaced. A new readout chip (SVX4) has been designed in radiation-hard 0.25 {mu}m, CMOS technology. Single-sided sensors are arranged in a compact structure, called a stave, with integrated readout and cooling systems. This paper describes the general design of the Run IIb system, testing results of prototype electrical components (staves), and prototype silicon sensor performance before and after irradiation.
Space-Time Structures from IIB Matrix Model
Aoki, H; Kawai, H; Kitazawa, Y; Tada, T
1998-01-01
We derive a long distance effective action for space-time coordinates from a IIB matrix model. It provides us an effective tool to study the structures of space-time. We prove the finiteness of the theory for finite $N$ to all orders of the perturbation theory. Space-time is shown to be inseparable and its dimensionality is dynamically determined. The IIB matrix model contains a mechanism to ensure the vanishing cosmological constant which does not rely on the manifest supersymmetry. We discuss possible mechanisms to obtain realistic dimensionality and gauge groups from the IIB matrix model.
Focal Cortical Dysplasia Type IIB and Human Papillomavirus
Directory of Open Access Journals (Sweden)
J. Gordon Millichap
2013-03-01
Full Text Available Researchers at Temple University School of Medicine, Philadelphia, PA tested the hypothesis that human papillomavirus type 16 oncoprotein E6 (HPV16 E6 is present in human focal cortical dysplasia type IIB (FCDIIB specimens.
Binary progenitor models of type IIb supernovae
Claeys, J S W; Pols, O R; Eldridge, J J; Baes, M
2011-01-01
Massive stars that lose their hydrogen-rich envelope down to a few tenths of a solar mass explode as extended type IIb supernovae, an intriguing subtype that links the hydrogen-rich type II supernovae with the hydrogen-poor type Ib and Ic. The progenitors may be very massive single stars that lose their envelope due to their stellar wind, but mass stripping due to interaction with a companion star in a binary system is currently considered to be the dominant formation channel. We computed an extensive grid of binary models with the Eggleton binary evolution code. The predicted rate from our standard models, which assume conservative mass transfer, is about 6 times smaller than the current rate indicated by observations. It is larger but still comparable to the rate expected from single stars. To recover the observed rate we must generously allow for uncertainties and low accretion efficiencies in combination with limited angular momentum loss from the system. Motivated by the claims of detection and non-detec...
Seifert, Alexander
2015-01-01
We construct global semi-realistic supersymmetric models with intersecting D6-branes on the non-factorisable orientifold $T^6/(\\mathbb{Z}_4\\times\\Omega\\mathcal{R})$. The non-factorisable structure gives rise to differences compared to the factorisable case: additional conditions for the three-cycles to be Lagrangian and extra constraints on the wrapping numbers for building fractional cycles.
Model building on the non-factorisable type IIA T{sup 6}/(Z{sub 4} x ΩR) orientifold
Energy Technology Data Exchange (ETDEWEB)
Seifert, Alexander; Honecker, Gabriele [Institute for Physics (WA THEP) and Cluster of Excellence PRISMA, Johannes Gutenberg University, Mainz (Germany)
2016-04-15
We construct global semi-realistic supersymmetric models with intersecting D6-branes on the non-factorisable orientifold T{sup 6}/(Z{sub 4} x ΩR). The non-factorisable structure gives rise to differences compared to the factorisable case: additional conditions for the three-cycles to be Lagrangian and extra constraints on the wrapping numbers for building fractional cycles. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Observation and interpretation of type IIb supernova explosions
Morales-Garoffolo, Antonia
2016-03-01
Core-collapse supernovae (CC-SNe) explosions represent the final demise of massive stars. Among the various types, there is a group of relatively infrequent CC-SNe termed type IIb, which appear to be hybrids between normal type II SNe (those characterised by H emission) and type Ib (those that lack H features in their spectra but exhibit prominent HeI lines). The nature of the stellar progenitors leading to type IIb SNe is currently unknown, although two channels are contemplated: single massive stars that have lost part of their outer envelope as a consequence of stellar winds, and massive stars that shed mass by Roche-Lobe overflow to a companion. The latter is in fact the favoured scenario for most of the objects observed up to now. In the majority of cases, when there are no direct progenitor detections, some hints about type IIb SN progenitors (e.g., initial mass) can be derived indirectly from the objects' light curves (LCs) and spectra. Motivated by the relatively few well-sampled observational datasets that exist up to date for type IIb SNe and the unknowns on their progenitors, we carried out extensive observations (mainly in the optical domain) for the young type IIb SNe 2011fu and 2013df. Both these SNe are particularly interesting because they show a first LC peak caused by shock breakout, followed by a secondary 56Ni-decay-powered maximum. The analysis of the data for SNe 2011fu and 2013df points to precursors that seem to have been stars with large radii (of the order of 100 RSun), with low mass hydrogen envelopes (tenths of MSun), and relatively low initial masses (12-18 MSun), which could have formed part of interacting binary systems. The nature of a third SN IIb candidate, OGLE-2013-SN-100, proved to be enigmatic. OGLE-2013-SN-100, shows a first peak in the LC, and other characteristics somewhat similar to those of type IIb SNe. However, after a deeper analysis, we conclude OGLE-2013-SN-100 is likely not a SN of type IIb. We provide an alternative
Holography of D-Brane Reconnection
Berg, M; Samtleben, H; Berg, Marcus; Hohm, Olaf; Samtleben, Henning
2007-01-01
Gukov, Martinec, Moore and Strominger found that the D1-D5-D5' system with the D5-D5' angle at 45 degrees admits a deformation "rho" preserving supersymmetry. Under this deformation, the D5-branes and D5'-branes reconnect along a single special Lagrangian manifold. We construct the near-horizon limit of this brane setup (for which no supergravity solution is currently known), imposing the requisite symmetries perturbatively in the deformation rho. Reducing to the three-dimensional effective gauged supergravity, we compute the scalar potential and verify the presence of a deformation with the expected properties. We compute the conformal dimensions as functions of rho. This spectrum naturally organizes into N=3 supermultiplets, corresponding to the 3/16 preserved by the brane system. We give some remarks on the symmetric orbifold CFT for Q_D5=Q_D5', outline the computation of rho-deformed correlators in this theory, and probe computations in our rho-deformed background.
D-branes and vacuum periodicity
Galtsov, D V; Galtsov, Dmitri; Dyadichev, Vladimir
2000-01-01
The superstring/M-theory suggests the Born-Infeld type modification of the classical gauge field lagrangian. We discuss how this changes topological issues related to vacuum periodicity in the SU(2) theory in four spacetime dimensions. A new feature, which is due to the breaking of scale invariance by the non-Abelian Born-Infeld (NBI) action, is that the potential barrier between the neighboring vacua is lowered to a finite height. At the top of the barrier one finds an infinite family of sphaleron-like solutions mediating transitions between different topological sectors. We review these solutions for two versions of the NBI action: with the ordinary and symmetrized trace. Then we show the existence of sphaleron excitations of monopoles in the NBI theory with the triplet Higgs. Soliton solutions in the constant external Kalb-Ramond field are also discussed which correspond to monopoles in the gauge theory on non-commutative space. A non-perturbative monopole solution for the non-commutative U(1) theory is pr...
Models of Inflation on D-Branes
Halyo, E
2003-01-01
We obtain models of chaotic, slow--roll, hybrid and D--term inflation from the Hanany--Witten brane configuration and its deformations. The deformations are given by the different orientations of the branes and control the parameters of the scalar potential such as the inflaton mass, Yukawa couplings and the anomalous D--term. The different inflationary models are continuously connected and arise in different limits of the parameter space. We describe a compactified version of the brane construction that also leads to models of inflation.
D-brane scattering and annihilation
D'Amico, Guido; Gobbetti, Roberto; Kleban, Matthew; Schillo, Marjorie
2015-01-01
We study the dynamics of parallel brane-brane and brane-antibrane scattering in string theory in flat spacetime, focusing on the pair production of open strings that stretch between the branes. We are particularly interested in the case of scattering at small impact parameter b
Attractor horizons in six-dimensional type IIB supergravity
Energy Technology Data Exchange (ETDEWEB)
Astefanesei, Dumitru, E-mail: dumitru.astefanesei@ucv.cl [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile); Miskovic, Olivera, E-mail: olivera.miskovic@ucv.cl [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile); Olea, Rodrigo, E-mail: rodrigo.olea@unab.cl [Universidad Andres Bello, Departamento de Ciencias Fisicas, Republica 220, Santiago (Chile)
2012-08-14
We consider near horizon geometries of extremal black holes in six-dimensional type IIB supergravity. In particular, we use the entropy function formalism to compute the charges and thermodynamic entropy of these solutions. We also comment on the role of attractor mechanism in understanding the entropy of the Hopf T-dual solutions in type IIA supergravity.
Seven-branes and instantons in type IIB supergravity
Hartong, Jelle
2008-01-01
F-theory provides a means to study the type IIB string theory in the non-perturbative regime where the complex coupling is of order unity. This should be contrasted with the perturbative regime where the string coupling is small. F-theory will be used in this thesis to argue for the existence of nov
Diagrammar and metamorphosis of coset symmetries in dimensionally reduced type IIB supergravity
Nurmagambetov, A J
2004-01-01
Studying the reduction of type IIB supergravity from ten to three space-time dimensions we describe the metamorphosis of Dynkin diagram for gravity line "caterpillar" into a type IIB supergravity "dragonfly" that is triggered by inclusion of scalars and antisymmetric tensor fields. The final diagram corresponds to type IIB string theory E8 global symmetry group which is the subgroup of the conjectured E11 hidden symmetry group. Application of the results for getting the type IIA/IIB T-duality rules and for searching for type IIB vacua solutions is considered.
Open string multi-branched and Kahler potentials
Carta, Federico; Staessens, Wieland; Zoccarato, Gianluca
2016-01-01
We consider type II string compactifications on Calabi-Yau orientifolds with fluxes and D-branes, and analyse the F-term scalar potential that simultaneously involves closed and open string modes. In type IIA models with D6-branes such potential can be directly computed by integrating out Minkowski three-forms. The result shows a multi-branched structure along the space of lifted open string moduli, in which discrete shifts in special Lagrangian and Wilson line deformations are compensated by changes in the RR flux quanta. The same sort of discrete shift symmetries are present in the superpotential and constrain the Kahler potential. As for the latter, inclusion of open string moduli breaks the factorisation between complex structure and Kahler moduli spaces. Nevertheless, the 4d Kahler metrics display a set of interesting relations that allow to rederive the scalar potential analytically. Similar results hold for type IIB flux compactifications with D7-brane Wilson lines.
Global embeddings for branes at toric singularities
Balasubramanian, Vijay; Braun, Volker; García-Etxebarria, Iñaki
2012-01-01
We describe how local toric singularities, including the Toric Lego construction, can be embedded in compact Calabi-Yau manifolds. We study in detail the addition of D-branes, including non-compact flavor branes as typically used in semi-realistic model building. The global geometry provides constraints on allowable local models. As an illustration of our discussion we focus on D3 and D7-branes on (the partially resolved) (dP0)^3 singularity, its embedding in a specific Calabi-Yau manifold as a hypersurface in a toric variety, the related type IIB orientifold compactification, as well as the corresponding F-theory uplift. Our techniques generalize naturally to complete intersections, and to a large class of F-theory backgrounds with singularities.
Mechanical properties of D0 Run IIB silicon detector staves
Energy Technology Data Exchange (ETDEWEB)
Lanfranco, Giobatta; Fast, James; /Fermilab
2001-06-01
A proposed stave design for the D0 Run IIb silicon tracker outer layers featuring central cooling channels and a composite shell mechanical structure is evaluated for self-deflection and deflection due to external loads. This paper contains an introduction to the stave structure, a section devoted to composite lamina and laminate properties and finally a section discussing the beam deflections expected for assembled staves using these laminates.
Fuzzy Spacetime with SU(3) Isometry in IIB Matrix Model
Kaneko, H; Tomino, D
2005-01-01
A group of fuzzy spacetime with SU(3) isometry is studied at the two loop level in IIB matrix model. It consists of spacetime from 4 to 6 dimensions, namely from CP2 to SU(3)/U(1)x U(1). The effective action scales in a universal manner in the large N limit as N and N^{4/3} on 4 and 6 dimensional manifolds respectively. The 4 dimensional spacetime CP2 possesses the smallest effective action in this class.
CDF Run IIb Silicon Vertex Detector DAQ Upgrade
Energy Technology Data Exchange (ETDEWEB)
S. Behari et al.
2003-12-18
The CDF particle detector operates in the beamline of the Tevatron proton-antiproton collider at Fermilab, Batavia, IL. The Tevatron is expected to undergo luminosity upgrades (Run IIb) in the future, resulting in a higher number of interactions per beam crossing. To operate in this dense radiation environment, an upgrade of CDF's silicon vertex detector (SVX) subsystem and a corresponding upgrade of its VME-based DAQ system has been explored. Prototypes of all the Run IIb SVX DAQ components have been constructed, assembled into a test stand and operated successfully using an adapted version of CDF's network-capable DAQ software. In addition, a PCI-based DAQ system has been developed as a fast and inexpensive tool for silicon detector and DAQ component testing in the production phase. In this paper they present an overview of the Run IIb silicon DAQ upgrade, emphasizing the new features and improvements incorporated into the constituent VME boards, and discuss a PCI-based DAQ system developed to facilitate production tests.
Spectropolarimetry of the Type IIb SN 2008aq
Stevance, H F; Baade, D; Hoflich, P; Patat, F; Spyromilio, J; Wheeler, J C; Clocchiatti, A; Wang, L; Yang, Y; Zelaya, P
2016-01-01
We present optical spectroscopy and spectropolarimetry of the Type IIb SN 2008aq 16 days and 27 days post-explosion. The spectrum of SN 2008aq remained dominated by Halpha P Cygni profile at both epochs, but showed a significant increase in the strength of the helium features, which is characteristic of the transition undergone by supernovae between Type IIb and Type Ib. Comparison of the spectra of SN 2008aq to other Type IIb SNe (SN 1993J, SN 2011dh, and SN 2008ax) at similar epochs revealed that the helium lines in SN 2008aq are much weaker, suggesting that its progenitor was stripped to a lesser degree. SN 2008aq also showed significant levels of continuum polarisation at p_cont = 0.70 (+/- 0.22) % in the first epoch, increasing to p_cont = 1.21 (+/- 0.33) % by the second epoch. Moreover, the presence of loops in the q-u planes of Halpha and He I in the second epoch suggests a departure from axial symmetry.
CDF Run IIb Silicon Vertex Detector DAQ Upgrade
Energy Technology Data Exchange (ETDEWEB)
S. Behari et al.
2003-12-18
The CDF particle detector operates in the beamline of the Tevatron proton-antiproton collider at Fermilab, Batavia, IL. The Tevatron is expected to undergo luminosity upgrades (Run IIb) in the future, resulting in a higher number of interactions per beam crossing. To operate in this dense radiation environment, an upgrade of CDF's silicon vertex detector (SVX) subsystem and a corresponding upgrade of its VME-based DAQ system has been explored. Prototypes of all the Run IIb SVX DAQ components have been constructed, assembled into a test stand and operated successfully using an adapted version of CDF's network-capable DAQ software. In addition, a PCI-based DAQ system has been developed as a fast and inexpensive tool for silicon detector and DAQ component testing in the production phase. In this paper they present an overview of the Run IIb silicon DAQ upgrade, emphasizing the new features and improvements incorporated into the constituent VME boards, and discuss a PCI-based DAQ system developed to facilitate production tests.
On the progenitor of the Type IIb supernova 2016gkg
Kilpatrick, Charles D.; Foley, Ryan J.; Abramson, Louis E.; Pan, Yen-Chen; Lu, Cicero-Xinyu; Williams, Peter; Treu, Tommaso; Siebert, Matthew R.; Fassnacht, Christopher D.; Max, Claire E.
2017-03-01
We present a detection in pre-explosion Hubble Space Telescope (HST) imaging of a point source consistent with being the progenitor star of the Type IIb supernova (SN IIb) 2016gkg. Post-explosion imaging from the Keck adaptive optics system was used to perform relative astrometry between the Keck and HST imaging. We identify a single point source in the HST images coincident with the SN position to 0.89σ. The HST photometry is consistent with the progenitor star being an A0 Ia star with T = 9500 K and log (L/L⊙) = 5.15. We find that the SN 2016gkg progenitor star appears more consistent with binary than single-star evolutionary models. In addition, early-time light-curve data from SN 2016gkg revealed a rapid rise in luminosity within ∼0.4 d of non-detection limits, consistent with models of the cooling phase after shock break-out. We use these data to determine an explosion date of 2016 September 20.15 and progenitor-star radius of log (R/R⊙) = 2.41, which agrees with photometry from the progenitor star. Our findings are also consistent with detections of other SNe IIb progenitor stars, although more luminous and bluer than most other examples.
Directory of Open Access Journals (Sweden)
Yao Wang
Full Text Available Cucurbitacin IIb (CuIIb is one of the major active compounds in Hemsleyadine tablets which have been used for clinical treatment of bacillary dysentery, enteritis and acute tonsilitis. However, its action mechanism has not been completely understood. This study aimed to explore the anti-inflammatory activity of CuIIb and its underlying mechanism in mitogen-activated lymphocytes isolated from mouse mesenteric lymph nodes. The results showed that CuIIb inhibited the proliferation of concanavalin A (Con A-activated lymphocytes in a time- and dose-dependent manner. CuIIb treatment arrested their cell cycle in S and G2/M phases probably due to the disruption of the actin cytoskeleton and the modulation of p27(Kip1 and cyclin levels. Moreover, the surface expression of activation markers CD69 and CD25 on Con A-activated CD3(+ T lymphocytes was suppressed by CuIIb treatment. Both Con A- and phorbol ester plus ionomycin-induced expression of TNF-α, IFN-γ and IL-6 proteins was attenuated upon exposure to CuIIb. Mechanistically, CuIIb treatment suppressed the phosphorylation of JNK and Erk1/2 but not p38 in Con A-activated lymphocytes. Although CuIIb unexpectedly enhanced the phosphorylation of IκB and NF-κB (p65, it blocked the nuclear translocation of NF-κB (p65. In support of this, CuIIb significantly decreased the mRNA levels of IκBα and TNF-α, two target genes of NF-κB, in Con A-activated lymphocytes. In addition, CuIIb downregulated Con A-induced STAT3 phosphorylation and increased cell apoptosis. Collectively, these results suggest that CuIIb exhibits its anti-inflammatory activity through modulating multiple cellular behaviors and signaling pathways, leading to the suppression of the adaptive immune response.
$\\mathcal{N}=1$ AdS$_4$ sourceless vacua in type IIB
Solard, Gautier
2016-01-01
In this paper, we are looking for $\\mathcal{N}=1$, AdS$_4$ sourceless vacua in type IIB. While several examples exist in type IIA , there exists only one example of such vacua in type IIB . Thanks to the framework of generalized geometry we were able to devise a semi-algorithmical method to look for sourceless vacua. We present this method, which can easily be generalized to more complex cases, and give two new sourceless vacua in type IIB.
Energy Technology Data Exchange (ETDEWEB)
Zhu, Jieqing; Zhu, Jianghai; Negri, Ana; Provasi, Davide; Filizola, Marta; Coller, Barry S.; Springer, Timothy A. (Sinai); (Rockefeller); (CH-Boston)
2011-08-24
The platelet integrin {alpha}{sub IIb}{beta}{sub 3} is essential for hemostasis and thrombosis through its binding of adhesive plasma proteins. We have determined crystal structures of the {alpha}{sub IIb}{beta}{sub 3} headpiece in the absence of ligand and after soaking in RUC-1, a novel small molecule antagonist. In the absence of ligand, the {alpha}{sub IIb}{beta}{sub 3} headpiece is in a closed conformation, distinct from the open conformation visualized in presence of Arg-Gly-Asp (RGD) antagonists. In contrast to RGD antagonists, RUC-1 binds only to the {alpha}{sub IIb} subunit. Molecular dynamics revealed nearly identical binding. Two species-specific residues, {alpha}{sub IIb} Y190 and {alpha}{sub aIIb} D232, in the RUC-1 binding site were confirmed as important by mutagenesis. In sharp contrast to RGD-based antagonists, RUC-1 did not induce {alpha}{sub IIb}{beta}{sub 3} to adopt an open conformation, as determined by gel filtration and dynamic light scattering. These studies provide insights into the factors that regulate integrin headpiece opening, and demonstrate the molecular basis for a novel mechanism of integrin antagonism.
Schroedinger invariant solutions of type IIB with enhanced supersymmetry
Energy Technology Data Exchange (ETDEWEB)
Donos, Aristomenis [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gauntlett, Jerome P. [Imperial College, London (United Kingdom). Theoretical Physics Group; Imperial College, London (United Kingdom). Inst. for Mathematical Sciences
2009-07-15
We construct the Killing spinors for a class of supersymmetric solutions of type IIB supergravity that are invariant under the non-relativistic Schroedinger algebra. The solutions depend on a five-dimensional Sasaki- Einstein space and it has been shown that they admit two Killing spinors. Here we will show that, for generic Sasaki-Einstein space, there are special subclasses of solutions which admit six Killing spinors and we determine the corresponding superisometry algebra. We also show that for the special case that the Sasaki-Einstein space is the round five-sphere, the number of Killing spinors can be increased to twelve. (orig.)
Vertex operators of ghost number three in Type IIB supergravity
Energy Technology Data Exchange (ETDEWEB)
Mikhailov, Andrei, E-mail: andrei@ift.unesp.br
2016-06-15
We study the cohomology of the massless BRST complex of the Type IIB pure spinor superstring in flat space. In particular, we find that the cohomology at the ghost number three is nontrivial and transforms in the same representation of the supersymmetry algebra as the solutions of the linearized classical supergravity equations. Modulo some finite dimensional spaces, the ghost number three cohomology is the same as the ghost number two cohomology. We also comment on the difference between the naive and semi-relative cohomology, and the role of b-ghost.
Shin-ya, Hagiwara; MASAYUKI, TAKAHASHI; Akihiko, Yamagishi; Division of Biological Sciences, Graduate School of Science, Hokkaido University
2001-01-01
The alternatively spliced isoform of the nonmuscle myosin heavy chain IIB (MHC-IIB) with an insert of 21 amino acids near the actin-binding region, MHC-IIB (B2), is expressed specifically in the brain and spinal cord in Mammalia and Aves. We performed immunoblot analyses to elucidate the distribution of MHC-IIB (B2) in the brains of various animals. Nearly half of MHC-IIB existed as the B2 inserted isoform (MHC-IIB (B2)) in the cerebrum of the guinea-pig, rabbit and pig, while the non-B2 inse...
Hagiwara, Shin-ya; Takahashi, Masayuki; Yamagishi, Akihiko
2001-01-01
The alternatively spliced isoform of the nonmuscle myosin heavy chain IIB (MHC-IIB) with an insert of 21 amino acids near the actin-binding region, MHC-IIB(B2), is expressed specifically in the brain and spinal cord in Mammalia and Aves. We performed immunoblot analyses to elucidate the distribution of MHC-IIB(B2) in the brains of various animals. Nearly half of MHC-IIB existed as the B2 inserted isoform (MHC-IIB(B2)) in the cerebrum of the guinea-pig, rabbit and pig, while the non-B2 inserte...
The Platelet Integrin αIIbβ3 Differentially Interacts with Fibrin Versus Fibrinogen.
Litvinov, Rustem I; Farrell, David H; Weisel, John W; Bennett, Joel S
2016-04-08
Fibrinogen binding to the integrin αIIbβ3 mediates platelet aggregation and spreading on fibrinogen-coated surfaces. However,in vivoαIIbβ3 activation and fibrinogen conversion to fibrin occur simultaneously, although the relative contributions of fibrinogenversusfibrin to αIIbβ3-mediated platelet functions are unknown. Here, we compared the interaction of αIIbβ3 with fibrin and fibrinogen to explore their differential effects. A microscopic bead coated with fibrinogen or monomeric fibrin produced by treating the immobilized fibrinogen with thrombin was captured by a laser beam and repeatedly brought into contact with surface-attached purified αIIbβ3. When αIIbβ3-ligand complexes were detected, the rupture forces were measured and displayed as force histograms. Monomeric fibrin displayed a higher probability of interacting with αIIbβ3 and a greater binding strength. αIIbβ3-fibrin interactions were also less sensitive to inhibition by abciximab and eptifibatide. Both fibrinogen- and fibrin-αIIbβ3 interactions were partially inhibited by RGD peptides, suggesting the existence of common RGD-containing binding motifs. This assumption was supported using the fibrin variants αD97E or αD574E with mutated RGD motifs. Fibrin made from a fibrinogen γ'/γ' variant lacking the γC αIIbβ3-binding motif was more reactive with αIIbβ3 than the parent fibrinogen. These results demonstrate that fibrin is more reactive with αIIbβ3 than fibrinogen. Fibrin is also less sensitive to αIIbβ3 inhibitors, suggesting that fibrin and fibrinogen have distinct binding requirements. In particular, the maintenance of αIIbβ3 binding activity in the absence of the γC-dodecapeptide and the α-chain RGD sequences suggests that the αIIbβ3-binding sites in fibrin are not confined to its known γ-chain and RGD motifs.
Thermal properties of D0 Run IIb silicon detector staves
Energy Technology Data Exchange (ETDEWEB)
Lanfranco, Giobatta; Fast, James; /Fermilab
2001-06-01
A proposed stave design for the D0 Run IIb silicon tracker outer layers featuring central cooling channels and hybrid substrates mounted directly to the silicon sensor surfaces is evaluated for heat transfer characteristics and thermal deflections. In order to control leakage current noise in the silicon it is necessary to maintain the silicon in Layer 2 (R {approx} 100mm) at or below +5C. The current cooling system using 30% ethylene glycol in water can deliver coolant to the inlet of the silicon tracker at a temperature of -8C to -10C. This paper also investigates some alternative coolant options for Run IIB. While these are not required for the outer layers of silicon, they may be needed for L0, which sits at R {approx} 15mm. In this case the silicon must be kept at or below -5C, very near the lower limit for delivery of 30% glycol/water coolant. However, for the inner layers the electronics will be mounted independently from the silicon so the local heat flux is greatly reduced. This paper does not consider the cooling issues for the inner layers.
Type IIB flux vacua from G-theory II
Candelas, Philip; Damian, Cesar; Larfors, Magdalena; Morales, Jose Francisco
2014-01-01
We find analytic solutions of type IIB supergravity on geometries that locally take the form $\\text{Mink}\\times M_4\\times \\mathbb{C}$ with $M_4$ a generalised complex manifold. The solutions involve the metric, the dilaton, NSNS and RR flux potentials (oriented along the $M_4$) parametrised by functions varying only over $\\mathbb{C}$. Under this assumption, the supersymmetry equations are solved using the formalism of pure spinors in terms of a finite number of holomorphic functions. Alternatively, the solutions can be viewed as vacua of maximally supersymmetric supergravity in six dimensions with a set of scalar fields varying holomorphically over $\\mathbb{C}$. For a class of solutions characterised by up to five holomorphic functions, we outline how the local solutions can be completed to four-dimensional flux vacua of type IIB theory. A detailed study of this global completion for solutions with two holomorphic functions has been carried out in the companion paper [1]. The fluxes of the global solutions ar...
Type IIB flux vacua from G-theory I
Candelas, Philip; Damian, Cesar; Larfors, Magdalena; Morales, Jose Francisco
2014-01-01
We construct non-perturbatively exact four-dimensional Minkowski vacua of type IIB string theory with non-trivial fluxes. These solutions are found by gluing together, consistently with U-duality, local solutions of type IIB supergravity on $T^4 \\times \\mathbb{C}$ with the metric, dilaton and flux potentials varying along $\\mathbb{C}$ and the flux potentials oriented along $T^4$. We focus on solutions locally related via U-duality to non-compact Ricci-flat geometries. More general solutions and a complete analysis of the supersymmetry equations are presented in the companion paper [1]. We build a precise dictionary between fluxes in the global solutions and the geometry of an auxiliary $K3$ surface fibered over $\\mathbb{CP}^1$. In the spirit of F-theory, the flux potentials are expressed in terms of locally holomorphic functions that parametrize the complex structure moduli space of the $K3$ fiber in the auxiliary geometry. The brane content is inferred from the monodromy data around the degeneration points o...
On the Progenitor of the Type IIb Supernova 2016gkg
Kilpatrick, Charles D; Abramson, Louis E; Pan, Yen-Chen; Lu, Cicero-Xinyu; Williams, Peter; Treu, Tommaso; Siebert, Matthew R; Fassnacht, Christopher D; Max, Claire E
2016-01-01
We present a detection in pre-explosion Hubble Space Telescope (HST) imaging of a point source consistent with being the progenitor star of the Type IIb supernova (SN IIb) 2016gkg. Post-explosion imaging from the Keck Adaptive Optics system was used to perform relative astrometry between the Keck and HST imaging. We identify a single point source in the HST images coincident with the SN position to 0.89-sigma. The HST photometry is consistent with the progenitor star being an A0Ia star with T=9500 K and log (L/Lsun)=5.15. We find that the SN 2016gkg progenitor star appears more consistent with binary than single-star evolutionary models. In addition, early-time light curve data from SN 2016gkg revealed a rapid rise in luminosity within ~0.4 days of non-detection limits, consistent with models of the cooling phase after shock break-out. We use these data to determine an explosion date of 20.15 September 2016 and progenitor star radius of log (R/Rsun)=2.41, which agrees with photometry from the progenitor star....
Effective Actions of IIB Matrix Model on S^3
Kaneko, Hiromichi; Matsumoto, Koichiro
2007-01-01
S^3 is a simple principle bundle which is locally S^2 \\times S^1. It has been shown that such a space can be constructed in terms of matrix models. It has been also shown that such a space can be realized by a generalized compactification procedure in the S^1 direction. We investigate the effective action of supersymmetric gauge theory on S^3 with an angular momentum cutoff and that of a matrix model compactification. The both cases can be realized in a deformed IIB matrix model with a Myers Term. We find that the highly divergent contributions at the tree and one loop level are sensitive to the uv cutoff. However the two loop level contributions are universal since they are only logarithmically divergent. We expect that the higher loop contributions are insensitive to the uv cutoff since 3d gauge theory is super renormalizable.
On Asymptotic Freedom and Confinement from Type-IIB Supergravity
Kehagias, A A
1999-01-01
We present a new type-IIB supergravity vacuum that describes the strong coupling regime of a non-supersymmetric gauge theory. The latter has a running coupling such that the theory becomes asymptotically free in the ultraviolet. It also has a running theta angle due to a non-vanishing axion field in the supergravity solution. We also present a worm-hole solution, which has finite action per unit four-dimensional volume and two asymptotic regions, a flat space and an AdS^5\\times S^5. The corresponding N=2 gauge theory, instead of being finite, has a running coupling. We compute the quark-antiquark potential in this case and find that it exhibits, under certain assumptions, area-law behaviour for large separations.
Recent developments in the type IIB matrix model
Nishimura, Jun
2014-01-01
We review recent developments in the type IIB matrix model, which was conjectured to be a nonperturbative formulation of superstring theory. In the first part we review the recent results for the Euclidean model, which suggest that SO(10) symmetry is spontaneously broken. In the second part we review the recent results for the Lorentzian model. In particular, we discuss Monte Carlo results, which suggest that (3+1)-dimensional expanding universe emerges dynamically. We also discuss some results suggesting the emergence of exponential expansion and the power-law expansion at later times. The behaviors at much later times are studied by the classical equation of motion. We discuss a solution representing 3d expanding space, which suggests a possible solution to the cosmological constant problem.
The Cassiopeia A supernova was of type IIb.
Krause, Oliver; Birkmann, Stephan M; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Rieke, George H; Misselt, Karl A
2008-05-30
Cassiopeia A is the youngest supernova remnant known in the Milky Way and a unique laboratory for supernova physics. We present an optical spectrum of the Cassiopeia A supernova near maximum brightness, obtained from observations of a scattered light echo more than three centuries after the direct light of the explosion swept past Earth. The spectrum shows that Cassiopeia A was a type IIb supernova and originated from the collapse of the helium core of a red supergiant that had lost most of its hydrogen envelope before exploding. Our finding concludes a long-standing debate on the Cassiopeia A progenitor and provides new insight into supernova physics by linking the properties of the explosion to the wealth of knowledge about its remnant.
Aspects of Moduli Stabilization in Type IIB String Theory
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Shaaban Khalil
2016-01-01
Full Text Available We review moduli stabilization in type IIB string theory compactification with fluxes. We focus on KKLT and Large Volume Scenario (LVS. We show that the predicted soft SUSY breaking terms in KKLT model are not phenomenological viable. In LVS, the following result for scalar mass, gaugino mass, and trilinear term is obtained: m0=m1/2=-A0=m3/2, which may account for Higgs mass limit if m3/2~O(1.5 TeV. However, in this case, the relic abundance of the lightest neutralino cannot be consistent with the measured limits. We also study the cosmological consequences of moduli stabilization in both models. In particular, the associated inflation models such as racetrack inflation and Kähler inflation are analyzed. Finally, the problem of moduli destabilization and the effect of string moduli backreaction on the inflation models are discussed.
On asymptotic freedom and confinement from type-IIB supergravity
Kehagias, A.; Sfetsos, K.
1999-06-01
We present a new type-IIB supergravity vacuum that describes the strong coupling regime of a non-supersymmetric gauge theory. The latter has a running coupling such that the theory becomes asymptotically free in the ultraviolet. It also has a running theta angle due to a non-vanishing axion field in the supergravity solution. We also present a worm-hole solution, which has finite action per unit four-dimensional volume and two asymptotic regions, a flat space and an AdS5xS5. The corresponding N=2 gauge theory, instead of being finite, has a running coupling. We compute the quark-antiquark potential in this case and find that it exhibits, under certain assumptions, an area-law behaviour for large separations.
Type IIB supergravity on squashed Sasaki-Einstein manifolds
Cassani, Davide; Faedo, Anton F
2010-01-01
We provide a consistent N=4 Kaluza-Klein truncation of type IIB supergravity on general 5-dimensional squashed Sasaki-Einstein manifolds. Our reduction ansatz keeps all and only the supergravity modes dual to the universal gauge sector of the associated conformal theories, via the gauge/gravity correspondence. The reduced 5-dimensional model displays remarkable features: it includes both zero-modes as well as massive iterations of the Kaluza-Klein operators on the internal manifold; it contains tensor fields dual to vectors charged under a non-abelian gauge group; it has a scalar potential with a non-supersymmetric AdS vacuum in addition to the supersymmetric one.
Affleck-Dine Baryogenesis in Type IIB String Models
Allahverdi, Rouzbeh; Muia, Francesco
2016-01-01
We present a viable string embedding of Affleck-Dine baryogenesis in type IIB sequestered models where the late-time decay of the lightest modulus reheats the universe to relatively low temperatures. We show that if inflation is driven by a blow-up Kaehler modulus, the Affleck-Dine field can become tachyonic during inflation if the Kaehler metric for matter fields has an appropriate inflaton-dependent contribution. We find that the Affleck-Dine mechanism can generate the observed baryon asymmetry for natural values of the underlying parameters which lead also to successful inflation and low-energy gaugino masses in a split supersymmetry scenario. The reheating temperature from the lightest modulus decay is high enough to allow thermal Higgsino-like dark matter.
Aspects of moduli stabilization in type IIB string theory
Khalil, Shaaban; Nassar, Ali
2015-01-01
We review moduli stabilization in type IIB string theory compactification with fluxes. We focus on the KKLT and Large Volume Scenario (LVS). We show that the predicted soft SUSY breaking terms in KKLT model are not phenomenological viable. In LVS, the following result for scalar mass, gaugino mass, and trilinear term is obtained: $m_0 =m_{1/2}= - A_0=m_{3/2}$, which may account for Higgs mass limit if $m_{3/2} \\sim {\\cal O}(1.5)$ TeV. However, in this case the relic abundance of the lightest neutralino can not be consistent with the measured limits. We also study the cosmological consequences of moduli stabilization in both models. In particular, the associated inflation models such as racetrack inflation and K\\"ahler inflation are analyzed. Finally the problem of moduli destabilization and the effect of string moduli backreaction on the inflation models are discussed.
Affleck-Dine baryogenesis in type IIB string models
Allahverdi, Rouzbeh; Cicoli, Michele; Muia, Francesco
2016-06-01
We propose a possible string embedding of Affleck-Dine baryogenesis in type IIB sequestered models where the late-time decay of the lightest modulus reheats the universe to relatively low temperatures. We show that if inflation is driven by a blow-up Kähler modulus, the Affleck-Dine field can become tachyonic during inflation if the Kähler metric for matter fields has an appropriate inflaton-dependent contribution. We find that the Affleck-Dine mechanism can generate the observed baryon asymmetry for natural values of the underlying parameters which lead also to successful inflation and low-energy gaugino masses in a split supersymmetry scenario. The reheating temperature from the lightest modulus decay is high enough to allow thermal Higgsino-like dark matter.
MHC-IIB filament assembly and cellular localization are governed by the rod net charge.
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Michael Rosenberg
Full Text Available BACKGROUND: Actin-dependent myosin II molecular motors form an integral part of the cell cytoskeleton. Myosin II molecules contain a long coiled-coil rod that mediates filament assembly required for myosin II to exert its full activity. The exact mechanisms orchestrating filament assembly are not fully understood. METHODOLOGY/PRINCIPAL FINDINGS: Here we examine mechanisms controlling filament assembly of non-muscle myosin IIB heavy chain (MHC-IIB. We show that in vitro the entire C-terminus region of net positive charge, found in myosin II rods, is important for self-assembly of MHC-IIB fragments. In contrast, no particular sequences in the rod region with net negative charge were identified as important for self-assembly, yet a minimal area from this region is necessary. Proper paracrystal formation by MHC-IIB fragments requires the 196aa charge periodicity along the entire coiled-coil region. In vivo, in contrast to self-assembly in vitro, negatively-charged regions of the coiled-coil were found to play an important role by controlling the intracellular localization of native MHC-IIB. The entire positively-charged region is also important for intracellular localization of native MHC-IIB. CONCLUSIONS/SIGNIFICANCE: A correct distribution of positive and negative charges along myosin II rod is a necessary component in proper filament assembly and intracellular localization of MHC-IIB.
Focal cortical dysplasia type IIa and IIb: MRI aspects in 118 cases proven by histopathology
Energy Technology Data Exchange (ETDEWEB)
Colombo, Nadia; Citterio, Alberto [Ospedale Ca Granda Niguarda, Department of Neuroradiology, Milano (Italy); Tassi, Laura; Mai, Roberto; Sartori, Ivana; Cardinale, Francesco; Lo Russo, Giorgio [Ospedale Niguarda, Claudio Munari Epilepsy Surgery Center, Milano (Italy); Deleo, Francesco; Spreafico, Roberto [IRCCS Foundation Neurological Institute ' ' C. Besta' ' , Department of Epilepsy Clinic and Experimental Neurophysiology, Milano (Italy); Bramerio, Manuela [Ospedale Niguarda, Department of Pathology, Milano (Italy)
2012-10-15
This study aims to review the magnetic resonance imaging (MRI) aspects of a large series of patients with focal cortical dysplasia type II (FCD II) and attempt to identify distinctive features in the two histopathological subtypes IIa and IIb. We retrospectively reviewed the MRI scans of 118 patients with histological proven FCD IIa (n = 37) or IIb (n = 81) who were surgically treated for intractable epilepsy. MRI was abnormal in 93 patients (79 %) and unremarkable in 25 (21 %). A dysplastic lesion was identified in 90 cases (97 %) and classified as FCD II in 83 and FCD non-II in seven cases. In three cases, the MRI diagnosis was other than FCD. There was a significant association between the presence of cortical thickening (p = 0.002) and the ''transmantle sign'' (p < 0.001) and a correct MRI diagnosis of FCD II. MRI positivity was more frequent in the patients with FCD IIb than in those with FCD IIa (91 % vs. 51 %), and the detection rate of FCD II was also better in the patients with type IIb (88 % vs. 32 %). The transmantle sign was significantly more frequent in the IIb subgroup (p = 0.003). The rates of abnormal MRI results and correct MRI diagnoses of FCD II were significantly higher in the IIb subgroup. Although other MRI stigmata may contribute to the diagnosis, the only significant correlation was between the transmantle sign and FCD IIb. (orig.)
Progress toward the Determination of Complete Vertex Operators for The IIB Matrix Model
Kitazawa, Y; Saito, O; Kitazawa, Yoshihisa; Mizoguchi, Shun'ya; Saito, Osamu
2006-01-01
We report on progress in determining the complete form of vertex operators for the IIB matrix model. The exact expressions are obtained for those emitting massless IIB supergravity fields up to sixth order in the light-cone superfield, in which the conjugate gravitino and conjugate two-form vertex operators are newly determined. We also provide a consistency check by computing the kinematical factor of a four-point graviton amplitude in a D-instanton background. We conjecture that the low-energy effective action of the IIB matrix model at large N is given by tree-level supergravity coupled to the vertex operators.
Integrin αIIb-mediated PI3K/Akt activation in platelets.
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Haixia Niu
Full Text Available Integrin αIIbβ3 mediated bidirectional signaling plays a critical role in thrombosis and haemostasis. Signaling mediated by the β3 subunit has been extensively studied, but αIIb mediated signaling has not been characterized. Previously, we reported that platelet granule secretion and TxA2 production induced by αIIb mediated outside-in signaling is negatively regulated by the β3 cytoplasmic domain residues R(724KEFAKFEEER(734. In this study, we identified part of the signaling pathway utilized by αIIb mediated outside-in signaling. Platelets from humans and gene deficient mice, and genetically modified CHO cells as well as a variety of kinase inhibitors were used for this work. We found that aggregation of TxA2 production and granule secretion by β3Δ724 human platelets initiated by αIIb mediated outside-in signaling was inhibited by the Src family kinase inhibitor PP2 and the PI3K inhibitor wortmannin, respectively, but not by the MAPK inhibitor U0126. Also, PP2 and wortmannin, and the palmitoylated β3 peptide R(724KEFAKFEEER(734, each inhibited the phosphorylation of Akt residue Ser473 and prevented TxA2 production and storage granule secretion. Similarly, Akt phosphorylation in mouse platelets stimulated by the PAR4 agonist peptide AYPGKF was αIIbβ3-dependent, and blocked by PP2, wortmannin and the palmitoylated peptide p-RKEFAKFEEER. Akt was also phosphorylated in response to mAb D3 plus Fg treatment of CHO cells in suspension expressing αIIbβ3-Δ724 or αIIbβ3E(724AERKFERKFE(734, but not in cells expressing wild type αIIbβ3. In summary, SFK(s and PI3K/Akt signaling is utilized by αIIb-mediated outside-in signaling to activate platelets even in the absence of all but 8 membrane proximal residues of the β3 cytoplasmic domain. Our results provide new insight into the signaling pathway used by αIIb-mediated outside-in signaling in platelets.
Supersymmetry of AdS and flat IIB backgrounds
Beck, S.; Gutowski, J.; Papadopoulos, G.
2015-02-01
We present a systematic description of all warped AdS n × w M 10- n and IIB backgrounds and identify the a priori number of supersymmetries N preserved by these solutions. In particular, we find that the AdS n backgrounds preserve for n ≤ 4 and for 4 < n ≤ 6 supersymmetries and for suitably restricted. In addition under some assumptions required for the applicability of the maximum principle, we demonstrate that the Killing spinors of AdS n backgrounds can be identified with the zero modes of Dirac-like operators on M 10- n establishing a new class of Lichnerowicz type theorems. Furthermore, we adapt some of these results to backgrounds with fluxes by taking the AdS radius to infinity. We find that these backgrounds preserve for 2 < n ≤ 4 and for 4 < n ≤ 7 supersymmetries. We also demonstrate that the Killing spinors of AdS n × w M 10- n do not factorize into Killing spinors on AdS n and Killing spinors on M 10- n .
Spectropolarimetry of the Type IIb Supernova 2001ig
Maund, J R; Patat, F; Wang, L; Baade, D; Hoflich, P A
2007-01-01
We present spectropolarimetric observations of the Type IIb SN 2001ig in NGC 7424; conducted with the ESO VLT FORS1 on 2001 Dec 16, 2002 Jan 3 and 2002 Aug 16 or 13, 31 and 256 days post-explosion. These observations are at three different stages of the SN evolution: (1) The hydrogen-rich photospheric phase, (2) the Type II to Type Ib transitional phase and (3) the nebular phase. At each of these stages, the observations show remarkably different polarization properties as a function of wavelength. We show that the degree of interstellar polarization is 0.17%. The low intrinsic polarization (~0.2%) at the first epoch is consistent with an almost spherical (<10% deviation from spherical symmetry) hydrogen dominated ejecta. Similar to SN 1987A and to Type IIP SNe, a sharp increase in the degree of the polarization (~1%) is observed when the outer hydrogen layer becomes optically thin by day 31; only at this epoch is the polarization well described by a ``dominant axis.'' The polarization angle of the data sh...
Duality covariant type IIB supersymmetry and nonperturbative consequences
Bars, Itzhak
1997-01-01
Type-IIB supersymmetric theories have an SL(2,Z) invariance, known as U-duality, which controls the non-perturbative behavior of the theory. Under SL(2,Z) the supercharges are doublets, implying that the bosonic charges would be singlets or triplets. However, among the bosonic charges there are doublet strings and doublet fivebranes which are in conflict with the doublet property of the supercharges. It is shown that the conflict is resolved by structure constants that depend on moduli, such as the tau parameter, which transform under the same SL(2,Z). The resulting superalgebra encodes the non-perturbative duality properties of the theory and is valid for any value of the string coupling constant. The usefulness of the formalism is illustrated by applying it to purely algebraic computations of the tension of (p,q) strings, and the mass and entropy of extremal blackholes constructed from D-1-branes and D-5-branes. In the latter case the non-perturbative coupling dependence of the BPS mass and metric is comput...
Kato, T; Horie, K; Hagiwara, T; Maeda, E; Tsumura, H; Ohashi, H; Miyazaki, H
1996-08-01
The recently cloned factor thrombopoietin (TPO) has been shown to exhibit megakaryocyte colony-stimulating activity in vitro. In this investigation, to further evaluate the action of TPO on megakaryocyte progenitor cells (colony-forming units-megakaryocyte [CFU-MK]), GpIIb/IIIa+ and GpIIb/IIIa- populations of CFU-MK were prepared from rat bone marrow cells based on their reactivity with P55 antibody, a monoclonal antibody against rat GpIIb/IIIa, and their responsiveness to recombinant human TPO (rhTPO) and recombinant rat interleukin-3 (rrIL-3) was examined using a megakaryocyte colony-forming assay (Meg-CSA). rhTPO supported only megakaryocyte colony growth from both fractions in a dose-dependent fashion. The mean colony size observed with the GpIIb/IIIa+ population was smaller than that seen with the GpIIb/IIIa- population. With the optimal concentration of either rhTPO or rrIL-3, similar numbers of megakaryocyte colonies were formed from the GpIIb/IIIa+ population previously shown to be highly enriched for CFU-MK. In contrast, the maximum number of megakaryocyte colonies from the GpIIb/IIIa- population stimulated by rhTPO was only 24.2% of that achieved with rrIL-3. Morphologic analysis of rhTPO-promoted megakaryocyte colonies from the GpIIb/IIIa+ population showed that the average colony size was smaller but that the mean diameter of individual megakaryocytes was larger than in megakaryocyte colonies promoted with rrIL-3. rhTPO plus rrIL-3, each at suboptimal concentrations, had an additive effect on proliferation of CFU-MK in the GpIIb/IIIa+ fraction, whereas rhTPO plus murine IL-6 or murine granulocyte-macrophage colony-stimulating factor (mG-M-CSF) modestly but significantly reduced megakaryocyte colony growth. These results indicate that TPO preferentially acts on GpIIb/IIIa+ late CFU-MK with lower proliferative capacity and interacts with some other cytokines in CFU-MK development.
CEACAM1 regulates integrin αIIbβ3-mediated functions in platelets.
Yip, Jana; Alshahrani, Musaed; Beauchemin, Nicole; Jackson, Denise E
2016-01-01
Previous studies have implicated that the Ig-ITIM superfamily member, CEACAM1 may regulate integrin function. While CEACAM1 has been demonstrated to play a role as an inhibitory co-receptor of ITAM-associated GPVI/FcR γ-chain signaling pathways in platelets, its physiologic role in integrin αIIbβ3-mediated platelet function is unclear. In this study, we investigate the functional importance of Ceacam1 in murine platelets. We show that CEACAM1 is constitutively associated with integrin αIIbβ3 in resting human and mouse platelets as demonstrated by co-immunoprecipitation studies. Using Ceacam1-deficient mice, we show that they have prolonged tail bleeding times and volume of blood lost that is corrected by reconstitution with platelet Ceacam1. Ceacam1(-/-) platelets have moderate integrin αIIbβ3 mediated functional defects with impaired kinetics of platelet spreading on fibrinogen and failure to retract fibrin clots in vitro. This functional integrin αIIbβ3 defect could not be attributed to altered integrin αIIbβ3 expression. Ceacam1(-/-) platelets displayed normal "inside-out" signaling properties as demonstrated by normal agonist-induced binding of soluble (fluorescein isothiocyanate) FITC-fibrinogen, JON/A antibody binding, and increases in cytosolic free calcium levels. This study provides direct evidence that Ceacam1 is essential for normal integrin αIIbβ3-mediated platelet function and that disruption of mouse Ceacam1 induced moderate integrin αIIbβ3-mediated functional defects.
Comparison of Diversity of Type IIb Supernovae with Asymmetry in Cassiopeia A Using Light Echoes
Finn, Kieran; Modjaz, Maryam; Liu, Yu-Qian; Rest, Armin
2016-01-01
We compare the diversity of spectral line velocities in a large sample of type IIb supernovae (SNe IIb) with the expected asphericity in the explosion, as measured from the light echoes of Cassiopeia A (Cas A), which was a historical galactic SN IIb. We revisit the results of Rest et al. (2011a), who used light echoes to observe Cas A from multiple lines of sight and hence determine its asphericity, as seen in the velocity of three spectral lines (He I $\\lambda$5876, H$\\alpha$ and the Ca II NIR triplet). We confirm and improve on this measurement by reproducing the effect of the light echoes in the spectra of several extragalactic SNe IIb found in the literature as well as a new SN IIb template recently created by Liu et al. (2015), and comparing these to the observed light echo spectra of Cas A, including their associated uncertainties. In order to quantify the accuracy of this comparison we smooth the light echo spectra of Cas A using Gaussian processes and we use a Monte Carlo method to measure the absorpt...
P-cadherin counteracts myosin II-B function: implications in melanoma progression
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De Wever Olivier
2010-09-01
Full Text Available Abstract Background Malignant transformation of melanocytes is frequently attended by a switch in cadherin expression profile as shown for E- and N-cadherin. For P-cadherin, downregulation in metastasizing melanoma has been demonstrated, and over-expression of P-cadherin in melanoma cell lines has been shown to inhibit invasion. The strong invasive and metastatic nature of cutaneous melanoma implies a deregulated interplay between intercellular adhesion and migration-related molecules Results In this study we performed a microarray analysis to compare the mRNA expression profile of an invasive BLM melanoma cell line (BLM LIE and the non-invasive P-cadherin over-expression variant (BLM P-cad. Results indicate that nonmuscle myosin II-B is downregulated in BLM P-cad. Moreover, myosin II-B plays a major role in melanoma migration and invasiveness by retracting the tail during the migratory cycle, as shown by the localization of myosin II-B stress fibers relative to Golgi and the higher levels of phosphorylated myosin light chain. Analysis of P-cadherin and myosin II-B in nodular melanoma sections and in a panel of melanoma cell lines further confirmed that there is an inverse relationship between both molecules. Conclusions Therefore, we conclude that P-cadherin counteracts the expression and function of myosin II-B, resulting in the suppression of the invasive and migratory behaviour of BLM melanoma cells
Analysis of Altered Micro RNA Expression Profiles in Focal Cortical Dysplasia IIB.
Li, Lin; Liu, Chang-Qing; Li, Tian-Fu; Guan, Yu-Guang; Zhou, Jian; Qi, Xue-Ling; Yang, Yu-Tao; Deng, Jia-Hui; Xu, Zhi-Qing David; Luan, Guo-Ming
2016-04-01
Focal cortical dysplasia type IIB is a commonly encountered subtype of developmental malformation of the cerebral cortex and is often associated with pharmacoresistant epilepsy. In this study, to investigate the molecular etiology of focal cortical dysplasia type IIB, the authors performed micro ribonucleic acid (RNA) microarray on surgical specimens from 5 children (2 female and 3 male, mean age was 73.4 months, range 50-112 months) diagnosed of focal cortical dysplasia type IIB and matched normal tissue adjacent to the lesion. In all, 24 micro RNAs were differentially expressed in focal cortical dysplasia type IIB, and the microarray results were validated using quantitative real-time polymerase chain reaction (PCR). Then the putative target genes of the differentially expressed micro RNAs were identified by bioinformatics analysis. Moreover, biological significance of the target genes was evaluated by investigating the pathways in which the genes were enriched, and the Hippo signaling pathway was proposed to be highly related with the pathogenesis of focal cortical dysplasia type IIB. © The Author(s) 2015.
Fibre inflation: observable gravity waves from IIB string compactifications
Energy Technology Data Exchange (ETDEWEB)
Cicoli, M.; Quevedo, F. [DAMTP, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom); Burgess, C.P., E-mail: M.Cicoli@damtp.cam.ac.uk, E-mail: cburgess@perimeterinstitute.ca, E-mail: F.Quevedo@damtp.cam.ac.uk [Perimeter Institute for Theoretical Physics, Waterloo, ON, N2L 2Y5 (Canada)
2009-03-15
We introduce a simple string model of inflation, in which the inflaton field can take trans-Planckian values while driving a period of slow-roll inflation. This leads naturally to a realisation of large field inflation, inasmuch as the inflationary epoch is well described by the single-field scalar potential V = V{sub 0}(3-4e{sup -{phi}/(3){sup 1{sup /{sup 2}}}}). Remarkably, for a broad class of vacua all adjustable parameters enter only through the overall coefficient V{sub 0}, and in particular do not enter into the slow-roll parameters. Consequently these are determined purely by the number of e -foldings, N{sub e}, and so are not independent: {epsilon} {approx_equal} 3/2{eta}{sup 2}. This implies similar relations among observables like the primordial scalar-to-tensor amplitude, r, and the scalar spectral tilt, n{sub s}: r {approx_equal} 6(n{sub s}-1){sup 2}. N{sub e} is itself more model-dependent since it depends partly on the post-inflationary reheat history. In a simple reheating scenario a reheating temperature of T{sub rh} {approx_equal} 10{sup 9} GeV gives N{sub e} {approx_equal} 58, corresponding to n{sub s} {approx_equal} 0.970 and r {approx_equal} 0.005, within reach of future observations. The model is an example of a class that arises naturally in the context of type IIB string compactifications with large-volume moduli stabilisation, and takes advantage of the generic existence there of Kaehler moduli whose dominant appearance in the scalar potential arises from string loop corrections to the Kaehler potential. The inflaton field is a combination of Kaehler moduli of a K3-fibered Calabi-Yau manifold. We believe there are likely to be a great number of models in this class-''high-fibre models''-in which the inflaton starts off far enough up the fibre to produce observably large primordial gravity waves.
Stability of Fuzzy S^2 x S^2 x S^2 in IIB Type Matrix Models
Kaneko, H; Tomino, D
2005-01-01
We study the stability of fuzzy S^2 x S^2 x S^2 backgrounds in three different IIB type matrix models with respect to the change of the spins of each S^2 at the two loop level. We find that S^2 x S^2 x S^2 background is metastable and the effective action favors a single large S^2 in comparison to the remaining S^2 x S^2 in the models with Myers term. On the other hand, we find that a large S^2 x S^2 in comparison to the remaining S^2 is favored in IIB matrix model itself. We further study the stability of fuzzy S^2 x S^2 background in detail in IIB matrix model with respect to the scale factors of each S^2 as well. In this case, we find unstable directions which lower the effective action away from the most symmetric fuzzy S^2 x S^2 background.
Free Differential Algebras and Pure Spinor Action in IIB Superstring Sigma Models
Oda, Ichiro
2011-01-01
In this paper we extend to the case of IIB superstring sigma models the method proposed in hep-th/10023500 to derive the pure spinor approach for type IIA sigma models. In particular, starting from the (Free) Differential Algebra and superspace parametrization of type IIB supergravity, extended to include the BRST differential and all the ghosts, we derive the BRST transformations of fields and ghosts as well as the standard pure spinor constraints for the ghosts $\\lambda $ related to supersymmetry. Moreover, using the method first proposed by us, we derive the pure spinor action for type IIB superstrings in curved supergravity backgrounds (on shell), in full agreement with the action first obtained by Berkovits and Howe.
Free differential algebras and pure spinor action in IIB superstring sigma models
Oda, Ichiro; Tonin, Mario
2011-06-01
In this paper we extend to the case of IIB superstring sigma models the method proposed in hep-th/10023500 to derive the pure spinor approach for type IIA sigma models. In particular, starting from the (Free) Differential Algebra and superspace parametrization of type IIB supergravity, extended to include the BRST differential and all the ghosts, we derive the BRST transformations of fields and ghosts as well as the standard pure spinor constraints for the ghosts λ related to supersymmetry. Moreover, using the method first proposed by us, we derive the pure spinor action for type IIB superstrings in curved supergravity backgrounds (on shell), in full agreement with the action first obtained by Berkovits and Howe.
Effects of escins Ia, Ib, IIa, and IIb from horse chestnuts on gastric emptying in mice.
Matsuda, H; Li, Y; Murakami, T; Yamahara, J; Yoshikawa, M
1999-03-05
Inhibitory effects of the saponin fraction and its principal constituents, escins Ia, Ib, IIa, and IIb, from horse chestnuts on gastric emptying were investigated in mice loaded with a non-nutrient or nutrient meal. The saponin fraction and escins Ia-IIb inhibited gastric emptying of a 1.5% carboxymethyl cellulose sodium salt (CMC-Na) meal by 11.1-54.2% (12.5-200 mg/kg). Escins Ia-IIb (50 mg/kg) also inhibited gastric emptying of a 40% glucose meal by 21.1-23.5% except for escin Ia, a milk meal by 18.4-33.1%, and a 30% ethanol meal by 13.5-15.9%. The effects of escins Ia-IIb on gastric emptying of the CMC-Na meal were attenuated by pretreatment with streptozotocin (100 mg/kg, i.v.), capsaicin (75 mg/kg in total, s.c.), or insulin (1 U/kg, s.c.). The effect of insulin was reduced by glucose (2 g/kg, i.v.) which can directly nourish the brain, but not by fructose (2 g/kg, i.v.) which cannot be utilized by the brain. The effects of escins Ia-IIb (50 mg/kg) were overridden in 60% ethanol-loaded mice, in which the central nervous system was suppressed by ethanol. These results suggest that capsaicin-sensitive sensory nerves and central nervous system partly participate in the effects of escins Ia-IIb.
A defined peptide that inhibits the formation of the glycoprotein IIb and IIIa complex.
Chiang, Thomas M; Zhu, Jiaqian
2005-01-01
Collagen-platelet interaction plays an important role in hemostasis and pathological thrombosis. The proposed mechanism of the interaction was the activation of platelets-->releasing of contents from granules-->aggregation. The common end point is the platelets and fibrin aggregates. Platelet glycoprotein (GP) IIb/IIIa (the alphaIIbbeta3 integrin) complexes serve as a receptor for the binding of fibrinogen to form firmed aggregates. Blockading of GP IIb/IIIa has been proposed to prevent platelet aggregation independent of the substance(s) responsible for activating the platelets. The development of various forms of GP IIb/IIIa inhibitor has resulted in the inhibition of platelet aggregation, although studies of alphaIIbbeta3 receptor function and various GP IIb/IIIa inhibitors have demonstrated the potential for these agents to produce effects on other aspects of platelet function as well as having nonplatelet effects. This study investigated platelet inhibition provided by blocking the GP IIb/IIIa complex formation by using a peptide derived from the GP IIIa molecule. The peptide inhibits both types I and III collagen-induced platelet aggregation in a dose-dependent manner. The defined peptide interferes with the formation of the GP IIb/IIIa complex by inhibiting the binding of FITC-PAC-1 onto ADP-, type I collagen-, and type III collagen-activated platelets. However, P-selectin secretion is not affected by the peptide. In addition, the peptide is not interfering with the binding of FITC-PAC-1 to platelets that were preincubated with indomethacin. Results from this study may suggest that the defined peptide is an effective agent to block the interaction of types I and III collagen with platelets.
Lu, Shajia; Horowits, Robert
2008-09-01
We investigated the role of nonmuscle myosin heavy chain (NMHC) IIB in cultured embryonic mouse cardiomyocytes by specific knockdown using RNA interference. NMHC IIB protein levels decreased 90% compared with mock-transfected cells by 3 days post transfection. NMHC IIB knockdown resulted in a slow decrease in N-RAP protein levels over 6 days with no change in N-RAP transcript levels. N-RAP is a scaffold for alpha-actinin and actin assembly during myofibrillogenesis, and we quantitated myofibril accumulation by morphometric analysis of alpha-actinin organization. Between 3 and 6 days, NMHC IIB knockdown was accompanied by the abolishment of cardiomyocyte spreading. During this period the rate of myofibril accumulation steadily decreased, correlating with the slowly decreasing levels of N-RAP. Between 6 and 8 days NMHC IIB and N-RAP protein levels recovered, and cardiomyocyte spreading and myofibril accumulation resumed. Inhibition of proteasome function using MG132 led to accumulation of excess N-RAP, and the secondary decrease in N-RAP that otherwise accompanied NMHC IIB knockdown was abolished. The results show that NMHC IIB knockdown led to decreased N-RAP levels through proteasome-mediated degradation. Furthermore, these proteins have distinct functional roles, with NMHC IIB playing a role in cardiomyocyte spreading and N-RAP functioning in myofibril assembly.
Early total thyroidectomy in patients with multiple endocrine neoplasia IIb syndrome.
Delius, R E; Thompson, N W
1989-11-01
Medullary carcinoma of the thyroid gland (MCT) develops at an early age in children with multiple endocrine neoplasia (MEN) IIb syndrome. Prompt diagnosis of the syndrome and early total thyroidectomy offer the only chance for cure. Surgical guidelines for managing the pediatric patient with potential for MCT have included screening with provocative calcitonin tests beginning at one year of age and total thyroidectomy performed when either basal calcitonin or stimulated test levels become abnormal. The diagnosis of MEN IIb, however, can be made on the basis of pathognomic clinical features, including characteristic facies, marfanoid body habitus, submucosal ganglioneuromas and thickened corneal nerves. A family is described herein in which one member had the pathognomonic clinical findings of MEN IIb but did not have an elevated level of serum calcitonin in response to stimulation with pentagastrin and calcium. Nonetheless, a total thyroidectomy was performed and multiple microscopic foci of MCT were found on pathologic examination. This suggests that total thyroidectomy should be performed upon any patient with the characteristic phenotype of MEN IIb, regardless of the results of the stimulation test for calcitonin.
IIB OSTEOSARCOMA - CURRENT MANAGEMENT, LOCAL-CONTROL, AND SURVIVAL STATISTICS - THE NETHERLANDS
VETH, RPH
Guarded optimism is justified in light of the results of treatment of IIB osteosarcoma in the Netherlands. This is due to improvements in diagnostic imaging techniques, staging, adjuvant chemotherapy, and surgical treatment. Five-year survival rates have increased from 25% to 80%. En bloc resection
van Montfort, Robert; Pijning, Tjaard; Kalk, Kornelis; Schuurman-Wolters, Gea K.; Reizer, Jonathan; Safer Jr., Milton H.; Robillard, George; Dijkstra, Bauke W.
1994-01-01
Crystals of enzyme IIB of the cellobiose-specific phosphotransferase system have been obtained from 15% polyethylene glycol 4000 using both streak-seeding and macroseeding techniques at 4°. Crystals were grown with the hanging drop method of vapour diffusion. Addition of 2-propanol and benzamidine/H
Directory of Open Access Journals (Sweden)
Rajesh Kumar Mandal
2014-01-01
Full Text Available Phakomatosis pigmentovascularis (PPV is a rare combination of pigmentary and vascular components with or without systemic involvement. We report here a rare association of Sturge-Weber syndrome, Klippel-Trenaunay syndrome, and PPV type IIb in a 15-year-old boy who had right upper limb monoparesis along with a history of recurrent convulsions.
30 CFR 57.22604 - Blasting from the surface (II-B mines).
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Blasting from the surface (II-B mines). 57.22604 Section 57.22604 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... MINES Safety Standards for Methane in Metal and Nonmetal Mines Explosives § 57.22604 Blasting from...
Solutions of type IIB and D=11 supergravity with Schroedinger(z) symmetry
Energy Technology Data Exchange (ETDEWEB)
Donos, Aristomenis [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gauntlett, Jerome P. [Imperial College, London (United Kingdom). Theoretical Physics Group; Imperial College, London (United Kingdom). Inst. for Mathematical Sciences
2009-05-15
We construct families of supersymmetric solutions of type IIB and D=11 supergravity that are invariant under the non-relativistic Schroedinger(z) algebra for various values of the dynamical exponent z. The new solutions are based on five- and seven-dimensional Sasaki-Einstein manifolds, respectively, and include supersymmetric solutions with z=2. (orig.)
Halyo, E
2004-01-01
We describe a model of P-term inflation on D5 branes wrapped on resolved and deformed $A_n$ type singularities. On the brane world--volume the resolution and deformation of the singularity correspond to an anomalous D-term and a linear term in the superpotential respectively. In the limiting cases with vanishing resolution or deformation we get F or D-term inflation as expected. We give a T-dual description of the model in terms of intersecting branes.
D branes in background fluxes and Nielsen-Olesen instabilities
Russo, Jorge G.
2016-06-01
In quantum field theory, charged particles with spin ≥ 1 may become tachyonic in the present of magnetic fluxes above some critical field, signaling an instability of the vacuum. The phenomenon is generic, in particular, similar instabilities are known to exist in open and closed string theory, where a spinning string state can become tachyonic above a critical field. In compactifications involving RR fluxes F p+2, the quantum states which could become tachyonic by the same Nielsen-Olesen mechanism are D p branes. By constructing an appropriate background with RR magnetic flux that takes into account back-reaction, we identify the possible tachyonic D p brane states and compute the formula for the energy spectrum in a sector. More generally, we argue that in any background RR magnetic flux, there are high spin D p quantum states which become very light at critical fields.
Stability of D-brane embeddings in nontrivial backgrounds
Energy Technology Data Exchange (ETDEWEB)
Anguelova, Lilia [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada); Institute for Nuclear Research and Nuclear Energy, BAS,Sofia (Bulgaria); Suranyi, Peter; Wijewardhana, L.C.R. [Department of Physics, University of Cincinnati,Cincinnati, OH 45221 (United States)
2014-01-27
We propose a new analytical method for determining whether nonsupersymmetric probe branes embedded in nontrivial backgrounds are perturbatively stable or not. The method is based on a relationship between zero mass solutions of the relevant DBI equations of motion and tachyonic solutions. Furthermore, due to the above relation, the question, of whether a classical solution is stable or not, can be answered simply by studying the derivatives of that solution with respect to its integration constants. Finally, we illustrate the efficiency of this method by applying it to several interesting examples.
Note about unstable D-branes with dynamical tension
KlusoÅ, J.
2016-08-01
We propose an action for an unstable Dp-brane with dynamical tension. We show that the equations of motion are equivalent to the equations of motion derived from Dirac-Born-Infeld and Wess-Zumino actions for a non-Bogomol'nyi-Prasad-Sommerfield Dp-brane. We also find the Hamiltonian formulation of this action and analyze the properties of the solutions corresponding to the tachyon vacuum and zero-tension solution.
D branes in background fluxes and Nielsen-Olesen instabilities
Russo, Jorge G
2016-01-01
In quantum field theory, charged particles with spin $\\geq 1$ may become tachyonic in the present of magnetic fluxes above some critical field, signaling an instability of the vacuum. The phenomenon is generic, in particular, similar instabilities are known to exist in open and closed string theory, where a spinning string state can become tachyonic above a critical field. In compactifications involving RR fluxes $F_{p+2}$, the quantum states which could become tachyonic by the same Nielsen-Olesen mechanism are Dp branes. By constructing an appropriate background with RR magnetic flux that takes into account back-reaction, we identify the possible tachyonic Dp brane states and compute the formula for the energy spectrum in a sector. More generally, we argue that in any background RR magnetic flux, there are high spin Dp quantum states which become very light at critical fields.
Note About Unstable D-Brane with Dynamical Tension
Kluson, J
2016-01-01
We propose an action for unstable Dp-brane with dynamical tension. We show that the equations of motion are equivalent to the equations of motion derived from DBI and WZ actions for non-BPS Dp-brane. We also find Hamiltonian formulation of this action and analyze properties of the solutions corresponding to the tachyon vacuum and zero tension solution.
D-branes and coherent topological charge structure in QCD
Thacker, Hank
2006-12-01
Monte Carlo studies of pure glue SU(3) gauge theory using the overlap-based topological charge operator have revealed a laminar structure in the QCD vacuum consisting of extended, thin, co- herent, locally 3-dimensional sheets of topological charge embedded in 4D space, with opposite sign sheets interleaved. Studies of localization properties of Dirac eigenmodes have also shown evidence for the delocalization of low-lying modes on effectively 3-dimensional surfaces. In this talk, I review some theoretical ideas which suggest the possibility of 3-dimensionally coherent topological charge structure in 4-dimensional gauge theory and provide a possible interpretation of the observed structure. I begin with Luscher's "Wilson bag" integral over the 3-index Chern- Simons tensor. The analogy with a Wilson loop as a charged world line in 2-dimensional CP N-1 sigma models suggests that the Wilson bag surface represents the world volume of a physical membrane. The large-N chiral Lagrangian arguments of Witten also indicate the existence of multiple "k-vacuum" states with discontinuous transitions between k-vacua at θ = odd multi- ples of π. The domain walls between these vacua have the properties of a Wilson bag surface. Finally, I review the AdS/CFT duality view of θ dependence in QCD. The dual realtionship be- tween topological charge in gauge theory and Ramond-Ramond charge in type IIA string theory suggests that the coherent topological charge sheets observed on the lattice are the holographic image of wrapped D6 branes.
Mirror Symmetry, D-Branes and Counting Holomorphic Discs
Aganagic, Mina; Vafa, Cumrun
2000-01-01
We consider a class of special Lagrangian subspaces of Calabi-Yau manifolds and identify their mirrors, using the recent derivation of mirror symmetry, as certain holomorphic varieties of the mirror geometry. This transforms the counting of holomorphic disc instantons ending on the Lagrangian submanifold to the classical Abel-Jacobi map on the mirror. We recover some results already anticipated as well as obtain some highly non-trivial new predictions.
Recombination of Intersecting D-Branes and Cosmological Inflation
Gómez-Reino, Marta
2002-01-01
We consider the interactions between Dp-branes intersecting at an arbitrary number of angles in the context of type II string theory. For cosmology purposes we concentrate in the theory on R^{3,1} x T^6. Interpreting the distance between the branes as the inflaton field, the branes can intersect at most at two angles in the compact space. If the configuration is non-supersymmetric we will have an interbrane potential that provides an effective cosmological inflationary epoch at the four dimensional intersection between the branes. The end of inflation occurs when the interbrane distance becomes small compared with the string scale, where a tachyon develops triggering the recombination of the branes. We study this recombination due to tachyon instabilities and we find the possibility for the final configuration to be again branes intersecting at two angles. This preserves the interesting features that are present in the intersecting brane models from the string model building point of view also after the end o...
D-brane Solitons in Supersymmetric Sigma-Models
Gauntlett, J P; Tong, D; Townsend, P K; Gauntlett, Jerome P.; Portugues, Rubén; Tong, David; Townsend, Paul K.
2001-01-01
Massive D=4 N=2 supersymmetric sigma models typically admit domain wall (Q-kink) solutions and string (Q-lump) solutions, both preserving 1/2 supersymmetry. We exhibit a new static 1/4 supersymmetric `kink-lump' solution in which a string ends on a wall, and show that it has an effective realization as a BIon of the D=4 super DBI-action. It is also shown to have a time-dependent Q-kink-lump generalization which reduces to the Q-lump in a limit corresponding to infinite BI magnetic field. All these 1/4 supersymmetric sigma-model solitons are shown to be realized in M-theory as calibrated, or `Q-calibrated', M5-branes in an M-monopole background.
D-branes and coherent topological charge structure in QCD
Thacker, H B
2006-01-01
Monte Carlo studies of pure glue SU(3) gauge theory using the overlap-based topological charge operator have revealed a laminar structure in the QCD vacuum consisting of extended, thin, coherent, locally 3-dimensional sheets of topological charge embedded in 4D space, with opposite sign sheets interleaved. Studies of localization properties of Dirac eigenmodes have also shown evidence for the delocalization of low-lying modes on effectively 3-dimensional surfaces. In this talk, I review some theoretical ideas which suggest the possibility of 3-dimensionally coherent topological charge structure in 4-dimensional gauge theory and provide a possible interpretation of the observed structure. I begin with Luscher's ``Wilson bag'' integral over the 3-index Chern-Simons tensor. The analogy with a Wilson loop as a charged world line in 2-dimensional $CP^{N-1}$ sigma models suggests that the Wilson bag surface represents the world volume of a physical membrane. The large-N chiral Lagrangian arguments of Witten also in...
Directory of Open Access Journals (Sweden)
Kou Y
2017-09-01
Full Text Available Yurong Kou,1,* Tengfei Zhao,2,* Shaohui Huang,2 Jie Liu,3 Weiyi Duan,2 Yunjing Wang,2 Zechen Wang,2 Delong Li,2 Chunliu Ning,2 Changfu Sun2 1Department of Oral Biology, School of Stomatology, China Medical University, Shenyang, Liaoning, People’s Republic of China; 2Department of Oral and Maxillofacial Surgery, School of Stomatology, China Medical University, Shenyang, Liaoning, People’s Republic of China; 3Centre of Science Experiment, China Medical University, Shenyang, Liaoning, People’s Republic of China *These authors contributed equally to this work Purpose: The aim of this study was to clarify whether level IIb dissection should be performed or avoided in the treatment of oral squamous cell carcinoma by meta-analysis.Materials and methods: Articles that were published before June 2017 were searched electronically in four databases (Web of Science, PubMed, Ovid and China National Knowledge Infrastructure without any date or language restrictions by two independent reviewers. Abstracts and full-text papers which investigated the cervical metastases to level IIb from primary head and neck cancers and were deemed potentially relevant were screened. Data were analyzed using RevMan 5.3.Results: Four hundred and fifty-five abstracts and 129 full-text papers were screened, and 22 studies were included in the analysis. Among the 2001 patients included, 112 patients had level IIb metastases, the pooled frequency of which was 6% (95% confidence interval [CI]: 4.0–7.0. Among the 400 patients with tongue squamous cell carcinoma from 12 studies, 37 patients had level IIb metastases, the pooled incidence of which was 7% (95% CI: 5.0–10.0. Metastases to level IIb always went together with level IIa, and only three patients were found to have isolated level IIb metastases without involving the other levels.Conclusion: Due to the low frequency of level IIb nodal metastases in oral squamous cell carcinoma patients and rare occurrence of isolated
On D-brane anti D-brane effective actions and their corrections to all orders in alpha-prime
Hatefi, Ehsan
2013-01-01
Based on a four point function, the S-matrix elements at disk level of the scattering amplitude of one closed string Ramond-Ramond field ($C$) and two tachyons and one scalar field, we find out new couplings in brane anti brane effective actions for $p=n,p+2=n$ cases. Using the infinite corrections of the vertex of one RR, one gauge and one scalar field and applying the correct expansion, it is investigated in details how we produce the infinite gauge poles of the amplitude for $p = n$ case. By discovering new higher derivative corrections of two tachyon-two scalar couplings in brane anti brane systems to all orders in $\\alpha'$, we also obtain the infinite scalar poles in $t'+s'+u$-channel in field theory. Working with the complete form of the amplitude with the closed form of the expansion and comparing all the infinite contact terms of this amplitude, we derive several new Wess-Zumino couplings with all their infinite higher derivative corrections in the world volume of brane anti brane systems. In particu...
On D-brane -anti D-brane effective actions and their all order bulk singularity structures
Energy Technology Data Exchange (ETDEWEB)
Hatefi, Ehsan [Centre for Research in String Theory, School of Physics and Astronomy,Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Institute for Theoretical Physics, TU Wien,Wiedner Hauptstrasse 8-10/136, A-1040 Vienna (Austria)
2016-04-27
All four point functions of brane anti brane system including their correct all order α{sup ′} corrections have been addressed. All five point functions of one closed string Ramond-Ramond (RR), two real tachyons and either one gauge field or the scalar field in both symmetric and asymmetric pictures have also been explored. The entire analysis of
On D-brane -anti D-brane effective actions and their all order bulk singularity structures
Hatefi, Ehsan
2016-04-01
All four point functions of brane anti brane system including their correct all order α' corrections have been addressed. All five point functions of one closed string Ramond-Ramond (RR), two real tachyons and either one gauge field or the scalar field in both symmetric and asymmetric pictures have also been explored. The entire analysis of is carried out. Not only does it fix the vertex operator of RR in asymmetric picture and in higher point functions of string theory amplitudes but also it confirms the fact that there is no issue of picture dependence of the mixed closed RR, gauge fields, tachyons and fermion fields in all symmetric or anti symmetric ones. We compute S-matrix in the presence of a transverse scalar field, two real tachyons and that reveals two different kinds of bulk singularity structures, involving an infinite number of u-channel gauge field and (u+s'+t')-channel scalar bulk poles. In order to produce all those bulk singularity structures, we define various couplings at the level of the effective field theory that involve the mixing term of Chern-Simons coupling (with C-potential field) and a covariant derivative of the scalar field that comes from the pull-back of brane. Eventually we explore their all order α' corrections in the presence of brane anti brane system where various remarks will be also pointed out.
On D-brane-Anti D-brane Effective actions and their all order Bulk Singularity Structures
Hatefi, Ehsan
2016-01-01
All four point functions of brane anti brane system including their correct all order $\\alpha'$ corrections have been addressed. All five point functions of one closed string Ramond-Ramond (RR), two real tachyons and either one gauge field or the scalar field in both symmetric and asymmetric pictures have also been explored. The entire analysis of $$ is carried out. Not only does it fix the vertex operator of RR in asymmetric picture and in higher point functions of string theory amplitudes but also it confirms the fact that there is no issue of picture dependence of the mixed closed RR, gauge fields, tachyons and fermion fields in all symmetric or anti symmetric ones. We compute $$ S-matrix in the presence of a transverse scalar field, two real tachyons and that reveals two different kinds of bulk singularity structures, involving an infinite number of $u'$ gauge field and $(u+s'+t')$ bulk poles. In order to produce all those bulk singularity structures, we define various couplings at the level of the effect...
On D-brane anti D-brane effective actions and their corrections to all orders in alpha-prime
Energy Technology Data Exchange (ETDEWEB)
Hatefi, Ehsan, E-mail: ehatefi@ictp.it [International Centre for Theoretical Physics, Strada Costiera 11, Trieste (Italy)
2013-09-01
Based on a four point function, the S-matrix elements at disk level of the scattering amplitude of one closed string Ramond-Ramond field (C) and two tachyons and one scalar field, we find out new couplings in brane anti brane effective actions for p = n, p+2 = n cases. Using the infinite corrections of the vertex of one RR, one gauge and one scalar field and applying the correct expansion, it is investigated in detail how we produce the infinite gauge poles of the amplitude for p = n case. By discovering new higher derivative corrections of two tachyon-two scalar couplings in brane anti brane systems to all orders in α', we also obtain the infinite scalar poles in (t'+s'+u)-channel in field theory. Working with the complete form of the amplitude with the closed form of the expansion and comparing all the infinite contact terms of this amplitude, we derive several new Wess-Zumino couplings with all their infinite higher derivative corrections in the world volume of brane anti brane systems. In particular, in producing all the infinite scalar poles of < V{sub C}V{sub φ}V{sub T}V{sub T} > , one has to consider the fact that scalar's vertex operator in (-1)-picture must carry the internal σ{sub 3} Chan-Paton matrix. The symmetric trace effective action has a non-zero coupling between Dφ{sup (1)i} and Dφ{sup (2)}{sub i} while this coupling does not exist in ordinary trace effective action.
Directory of Open Access Journals (Sweden)
Wen Hwa Lee
Full Text Available Agonist-stimulated platelet activation triggers conformational changes of integrin αIIbβ3, allowing fibrinogen binding and platelet aggregation. We have previously shown that an octapeptide, p1YMESRADR8, corresponding to amino acids 313-320 of the β-ribbon extending from the β-propeller domain of αIIb, acts as a potent inhibitor of platelet aggregation. Here we have performed in silico modelling analysis of the interaction of this peptide with αIIbβ3 in its bent and closed (not swing-out conformation and show that the peptide is able to act as a substitute for the β-ribbon by forming a clasp restraining the β3 hybrid and βI domains in a closed conformation. The involvement of species-specific residues of the β3 hybrid domain (E356 and K384 and the β1 domain (E297 as well as an intrapeptide bond (pE315-pR317 were confirmed as important for this interaction by mutagenesis studies of αIIbβ3 expressed in CHO cells and native or substituted peptide inhibitory studies on platelet functions. Furthermore, NMR data corroborate the above results. Our findings provide insight into the important functional role of the αIIb β-ribbon in preventing integrin αIIbβ3 head piece opening, and highlight a potential new therapeutic approach to prevent integrin ligand binding.
T-dualization of type IIB superstring theory in double space
Nikolić, Bojan
2015-01-01
In this article we offer the new interpretation of T-dualization procedure of type IIB superstring theory in double space framework. We use the ghost free action of type IIB superstring in pure spinor formulation in approximation of constant background fields up to the quadratic terms. T-dualization along any subset of the initial coordinates, $x^a$, is equivalent to the permutation of this subset with subset of the corresponding T-dual coordinates, $y_a$, in double space coordinate $Z^M=(x^\\mu,y_\\mu)$. Demanding that the T-dual transformation law after exchange $x^a\\leftrightarrow y_a$ has the same form as initial one, we obtain the T-dual NS-NS and NS-R background fields. The T-dual R-R field strength is determined up to one arbitrary constant under some assumptions.
Supersymmetric AdS{sub 6} solutions of type IIB supergravity
Energy Technology Data Exchange (ETDEWEB)
Kim, Hyojoong, E-mail: h.kim@khu.ac.kr; Kim, Nakwoo, E-mail: nkim@khu.ac.kr [Department of Physics and Research Institute of Basic Science, Kyung Hee University, 130-701, Seoul (Korea, Republic of); Suh, Minwoo, E-mail: minsuh@usc.edu [Department of Physics, Sogang University, 121-742, Seoul (Korea, Republic of)
2015-10-11
We study the general requirement for supersymmetric AdS{sub 6} solutions in type IIB supergravity. We employ the Killing spinor technique and study the differential and algebraic relations among various Killing spinor bilinears to find the canonical form of the solutions. Our result agrees precisely with the work of Apruzzi et al. (JHEP 1411:099, 2014), which used the pure spinor technique. Hoping to identify the geometry of the problem, we also computed four-dimensional theory through the dimensional reduction of type IIB supergravity on AdS{sub 6}. This effective action is essentially a non-linear sigma model with five scalar fields parametrizing SL(3,ℝ)/SO(2,1), modified by a scalar potential and coupled to Einstein gravity in Euclidean signature. We argue that the scalar potential can be explained by a subgroup CSO(1,1,1) ⊂SL(3,ℝ) in a way analogous to gauged supergravity.
Supersymmetric AdS{sub 6} solutions of type IIB supergravity
Energy Technology Data Exchange (ETDEWEB)
Kim, Hyojoong; Kim, Nakwoo [Kyung Hee University, Department of Physics and Research Institute of Basic Science, Seoul (Korea, Republic of); Suh, Minwoo [Sogang University, Department of Physics, Seoul (Korea, Republic of)
2015-10-15
We study the general requirement for supersymmetric AdS{sub 6} solutions in type IIB supergravity. We employ the Killing spinor technique and study the differential and algebraic relations among various Killing spinor bilinears to find the canonical form of the solutions. Our result agrees precisely with the work of Apruzzi et al. (JHEP 1411:099, 2014), which used the pure spinor technique. Hoping to identify the geometry of the problem, we also computed four-dimensional theory through the dimensional reduction of type IIB supergravity on AdS{sub 6}. This effective action is essentially a non-linear sigma model with five scalar fields parametrizing SL(3,R)/ SO(2,1), modified by a scalar potential and coupled to Einstein gravity in Euclidean signature. We argue that the scalar potential can be explained by a subgroup CSO(1,1,1) is contained in SL(3,R) in a way analogous to gauged supergravity. (orig.)
Tiny graviton matrix theory: DLCQ of IIB plane-wave string theory, a conjecture
Energy Technology Data Exchange (ETDEWEB)
Sheikh-Jabbari, Mohammad M. [Department of Physics, Stanford University, 382 via Pueblo Mall, Stanford CA 94305-4060 (United States)]. E-mail: jabbari@itp.stanford.edu
2004-09-01
We conjecture that the discrete light-cone quantization (DLCQ) of strings on the maximally supersymmetric type IIB plane-wave background in the sector with J units of light-cone momentum is a supersymmetric 0+1 dimensional U(J) gauge theory (quantum mechanics) with PSU(2|2) x PSU(2|2) x U(1) superalgebra. The conjectured hamiltonian for the plane-wave matrix (string) theory, the tiny graviton matrix theory, is the quantized (regularized) three brane action on the same background. We present some pieces of evidence for this conjecture through analysis of the hamiltonian , its vacua, spectrum and coupling constant. Moreover, we discuss an extension of our conjecture to the DLCQ of type IIB strings on AdS{sub 5} x S{sup 5} geometry. (author)
A Spin(7) Conifold Transition in Type IIB as an F-theory Flop
Tan, M C; Teo, Edward
2004-01-01
We consider type IIB string theory compactified on an 8-dimensional Spin(7) manifold with N D5-branes, undergoing a conifold transition to a geometry with no branes and N units of dual 3-form RR flux through appropriate 3-cycles. We show that at {\\it constant} IIB coupling, in the limit of large N and finite 't Hooft coupling, this conifold transition can be lifted to a purely geometric S^5 flop in the 11-dimensional space of an equivalent F-theory without branes and fluxes. The S^5 flop in this equivalent F-theory is a higher-dimensional analogue of the S^3 flop in M-theory on a G_2 manifold discovered by Atiyah et al., albeit resulting in a theory with {\\cal N}=1 in d=2 instead of d=4.
Models of Particle Physics from Type IIB String Theory and F-theory: A Review
Maharana, Anshuman
2012-01-01
We review particle physics model building in type IIB string theory and F-theory. This is a region in the landscape where in principle many of the key ingredients required for a realistic model of particle physics can be combined successfully. We begin by reviewing moduli stabilisation within this framework and its implications for supersymmetry breaking. We then review model building tools and developments in the weakly coupled type IIB limit, for both local D3-branes at singularities and global models of intersecting D7-branes. Much of recent model building work has been in the strongly coupled regime of F-theory due to the presence of exceptional symmetries which allow for the construction of phenomenologically appealing Grand Unified Theories. We review both local and global F-theory model building starting from the fundamental concepts and tools regarding how the gauge group, matter sector and operators arise, and ranging to detailed phenomenological properties explored in the literature.
Patko, Zsofia; Csaszar, Albert; Acsady, Gyorgy; Peter, Karlheinz; Schwarz, Meike
2012-01-01
Circulating platelet-leukocyte hetero-aggregates play an important role in acute cardiovascular events and hypersensitivity reactions. The association involves the receptor families of selectins and integrin. The objective of this study was to investigate the role of CD11b/CD18 integrin (Mac-1) in hetero-aggregate formation and search for a counter-receptor on platelets ready to interact with Mac-1. As a model of leukocytes, Mac-1 presenting Chinese hamster ovary (CHO) cells were used to evaluate the role of Mac-1 in hetero-aggregate formation. The amount of CHO cell-bound active and inactive platelets was measured by flow cytometry, while the counter-receptors on platelets were identified via using blocking antibodies. We observed significant platelet adhesion on Mac-1-bearing cells when platelet-rich plasma or activated platelets were present. Inactive platelets did not adhere to Mac-1-bearing cells. Addition of fibrinogen, a ligand of Mac-1 significantly increased platelet binding. CD40L was demonstrated to act similarly on Mac-1. Inhibition of platelet GpIIb/IIIa completely abolished CHO cell-platelet aggregation. In our study, we have shown for the first time that Mac-1 mediates the formation of hetero-aggregates without selectin tethering when Mac-1 ligands such as fibrinogen or CD40L are present and blockers of platelet GpIIb/IIIa are able to diminish this interaction.
Di-J/Ψ Studies, Level 3 Tracking and the D0 Run IIb Upgrade
Energy Technology Data Exchange (ETDEWEB)
Vint, Philip John [Imperial College, London (United Kingdom)
2010-02-01
The D0 detector underwent an upgrade to its silicon vertex detector and triggering systems during the transition from Run IIa to Run IIb to maximize its ability to fully exploit Run II at the Fermilab Tevatron. This thesis describes improvements made to the tracking and vertexing algorithms used by the high level trigger in both Run IIa and Run IIb, as well as a search for resonant di-J/Ψ states using both Run IIa and Run IIb data. Improvements made to the tracking and vertexing algorithms during Run IIa included the optimization of the existing tracking software to reduce overall processing time and the certification and testing of a new software release. Upgrades made to the high level trigger for Run IIb included the development of a new tracking algorithm and the inclusion of the new Layer 0 silicon detector into the existing software. The integration of Layer 0 into the high level trigger has led to an improvement in the overall impact parameter resolution for tracks of ~50%. The development of a new parameterization method for finding the error associated to the impact parameter of tracks returned by the high level tracking algorithm, in association with the inclusion of Layer 0, has led to improvements in vertex resolution of ~4.5 μm. A previous search in the di-J/Ψ channel revealed a unpredicted resonance at ~13.7 GeV/c^{2}. A confirmation analysis is presented using 2.8 fb^{-1} of data and two different approaches to cuts. No significant excess is seen in the di-J/Ψ mass spectrum.
Buitrago, Lorena; Rendon, Augusto; Liang, Yupu; Simeoni, Ilenia; Negri, Ana; Filizola, Marta; Ouwehand, Willem H.; Coller, Barry S.; Alessi, Marie-Christine; Ballmaier, Matthias; Bariana, Tadbir; Bellissimo, Daniel; Bertoli, Marta; Bray, Paul; Bury, Loredana; Carrell, Robin; Cattaneo, Marco; Collins, Peter; French, Deborah; Favier, Remi; Freson, Kathleen; Furie, Bruce; Germeshausen, Manuela; Ghevaert, Cedric; Gomez, Keith; Goodeve, Anne; Gresele, Paolo; Guerrero, Jose; Hampshire, Dan J.; Hadinnapola, Charaka; Heemskerk, Johan; Henskens, Yvonne; Hill, Marian; Hogg, Nancy; Johnsen, Jill; Kahr, Walter; Kerr, Ron; Kunishima, Shinji; Laffan, Michael; Natwani, Amit; Neerman-Arbez, Marguerite; Nurden, Paquita; Nurden, Alan; Ormiston, Mark; Othman, Maha; Ouwehand, Willem; Perry, David; Vilk, Shoshana Ravel; Reitsma, Pieter; Rondina, Matthew; Simeoni, Ilenia; Smethurst, Peter; Stephens, Jonathan; Stevenson, William; Szkotak, Artur; Turro, Ernest; Van Geet, Christel; Vries, Minka; Ward, June; Waye, John; Westbury, Sarah; Whiteheart, Sidney; Wilcox, David; Zhang, Bi
2015-01-01
Next-generation sequencing is transforming our understanding of human genetic variation but assessing the functional impact of novel variants presents challenges. We analyzed missense variants in the integrin αIIbβ3 receptor subunit genes ITGA2B and ITGB3 identified by whole-exome or -genome sequencing in the ThromboGenomics project, comprising ∼32,000 alleles from 16,108 individuals. We analyzed the results in comparison with 111 missense variants in these genes previously reported as being associated with Glanzmann thrombasthenia (GT), 20 associated with alloimmune thrombocytopenia, and 5 associated with aniso/macrothrombocytopenia. We identified 114 novel missense variants in ITGA2B (affecting ∼11% of the amino acids) and 68 novel missense variants in ITGB3 (affecting ∼9% of the amino acids). Of the variants, 96% had minor allele frequencies (MAF) < 0.1%, indicating their rarity. Based on sequence conservation, MAF, and location on a complete model of αIIbβ3, we selected three novel variants that affect amino acids previously associated with GT for expression in HEK293 cells. αIIb P176H and β3 C547G severely reduced αIIbβ3 expression, whereas αIIb P943A partially reduced αIIbβ3 expression and had no effect on fibrinogen binding. We used receiver operating characteristic curves of combined annotation-dependent depletion, Polyphen 2-HDIV, and sorting intolerant from tolerant to estimate the percentage of novel variants likely to be deleterious. At optimal cut-off values, which had 69–98% sensitivity in detecting GT mutations, between 27% and 71% of the novel αIIb or β3 missense variants were predicted to be deleterious. Our data have implications for understanding the evolutionary pressure on αIIbβ3 and highlight the challenges in predicting the clinical significance of novel missense variants. PMID:25827233
β-Subunit Binding Is Sufficient for Ligands to Open the Integrin αIIbβ3 Headpiece.
Lin, Fu-Yang; Zhu, Jianghai; Eng, Edward T; Hudson, Nathan E; Springer, Timothy A
2016-02-26
The platelet integrin αIIbβ3 binds to a KQAGDV motif at the fibrinogen γ-chain C terminus and to RGD motifs present in loops in many extracellular matrix proteins. These ligands bind in a groove between the integrin α and β-subunits; the basic Lys or Arg side chain hydrogen bonds to the αIIb-subunit, and the acidic Asp side chain coordinates to a metal ion held by the β3-subunit. Ligand binding induces headpiece opening, with conformational change in the β-subunit. During this opening, RGD slides in the ligand-binding pocket toward αIIb, with movement of the βI-domain β1-α1 loop toward αIIb, enabling formation of direct, charged hydrogen bonds between the Arg side chain and αIIb. Here we test whether ligand interactions with β3 suffice for stable ligand binding and headpiece opening. We find that the AGDV tetrapeptide from KQAGDV binds to the αIIbβ3 headpiece with affinity comparable with the RGDSP peptide from fibronectin. AGDV induced complete headpiece opening in solution as shown by increase in hydrodynamic radius. Soaking of AGDV into closed αIIbβ3 headpiece crystals induced intermediate states similarly to RGDSP. AGDV has very little contact with the α-subunit. Furthermore, as measured by epitope exposure, AGDV, like the fibrinogen γ C-terminal peptide and RGD, caused integrin extension on the cell surface. Thus, pushing by the β3-subunit on Asp is sufficient for headpiece opening and ligand sliding, and no pulling by the αIIb subunit on Arg is required.
Type IIB String Backgrounds on Parallelizable PP-Waves and Conformal Liouville Theory
Hssaini, M
2003-01-01
The scope of this work concerns the adaptation of the parallelizability pp-wave (Ppp-wave) process to D=10 type IIB string backgrounds in the presence of the non-trivial anti-self dual R-R 5-form $\\QTR{cal}{F}$. This is important in the sense that it gives rise to some unsuspected properties. In fact, exact solutions of type IIB string backgrounds on Ppp-waves are discussed. For the $u$-dependence of the dilaton field $\\Phi $, we establish explicitly a correspondence between type IIB supergravity equations of motion and 2d-conformal Liouville field theory. We show also that the corresponding conserved conformal current $T(\\Phi)$ coincides exactly with the trace of the symmetric matrix $\\mu_{ij}$ appearing in the quadratic front factor $F=\\mu _{ij}x^{i}x^{j}$ of the Ppp-wave. Furthermore, we consider the transverse space dependence of the dilaton $\\Phi $ and show that the supergravity equations are easily solved for the linear realization of the dilaton field. Other remarkable properties related to this case a...
The progenitor and early evolution of the Type IIb SN 2016gkg
Tartaglia, L; Sand, D J; Valenti, S; Smartt, S J; McCully, C; Anderson, J P; Arcavi, I; Elias-Rosa, N; Galbany, L; Gal-Yam, A; Haislip, J B; Hosseinzadeh, G; Howell, D A; Inserra, C; Jha, S W; Kankare, E; Lundqvist, P; Maguire, K; Mattila, S; Reichart, D; Smith, K W; Smith, M; Stritzinger, M; Sullivan, M; Taddia, F; Tomasella, L
2016-01-01
We report initial observations and analysis on the Type IIb SN 2016gkg in the nearby galaxy NGC 613. SN 2016gkg exhibited a clear double-peaked light curve during its early evolution, as evidenced by our intensive spectroscopic and photometric follow-up campaign. SN 2016gkg shows strong similarities with other Type IIb SNe, in particular with respect to the \\he emission features observed $\\sim\\,9\\,\\rm{days}$ after explosion in both the optical and near infrared. SN 2016gkg evolved faster than the prototypical Type IIb SN 1993J, with a decline similar to that of SN 2011dh after the first peak. Archival {\\it Hubble Space Telescope} images indicate a pre-explosion source at SN 2016gkg's position, suggesting a progenitor star with a $\\sim$mid F spectral type and initial mass $15-20$\\msun, depending on the distance modulus adopted for NGC 613. Modeling the temperature evolution within $5\\,\\rm{days}$ of explosion, we obtain a progenitor radius of $\\sim\\,60-120$\\rsun, consistent with the spectral type obtained from ...
Two CRM protein subfamilies cooperate in the splicing of group IIB introns in chloroplasts.
Asakura, Yukari; Bayraktar, Omer Ali; Barkan, Alice
2008-11-01
Chloroplast genomes in angiosperms encode approximately 20 group II introns, approximately half of which are classified as subgroup IIB. The splicing of all but one of the subgroup IIB introns requires a heterodimer containing the peptidyl-tRNA hydrolase homolog CRS2 and one of two closely related proteins, CAF1 or CAF2, that harbor a recently recognized RNA binding domain called the CRM domain. Two CRS2/CAF-dependent introns require, in addition, a CRM domain protein called CFM2 that is only distantly related to CAF1 and CAF2. Here, we show that CFM3, a close relative of CFM2, associates in vivo with those CRS2/CAF-dependent introns that are not CFM2 ligands. Mutant phenotypes in rice and Arabidopsis support a role for CFM3 in the splicing of most of the introns with which it associates. These results show that either CAF1 or CAF2 and either CFM2 or CFM3 simultaneously bind most chloroplast subgroup IIB introns in vivo, and that the CAF and CFM subunits play nonredundant roles in splicing. These results suggest that the expansion of the CRM protein family in plants resulted in two subfamilies that play different roles in group II intron splicing, with further diversification within a subfamily to accommodate multiple intron ligands.
Cho, Chul-Hyun; Jung, Jae-Hoon; Kim, Beom-Soo
2017-05-01
The purpose of this study was to evaluate the radiologic and clinical outcomes of coracoclavicular (CC) stabilization using a suture button device for Neer type IIB lateral clavicle fractures. Eighteen consecutive patients with Neer type IIB fractures were treated with CC stabilization using a TightRope device (Arthrex, Naples, FL, USA). The mean follow-up period was 46.6 months (range, 24-75 months). Radiologic outcomes were assessed using serial plain radiographs. Clinical outcomes were evaluated using the visual analog scale pain score; University of California, Los Angeles score; American Shoulder and Elbow Surgeons score; and subjective shoulder value. Intraoperative and postoperative complications were also evaluated. Of the 18 cases, 17 (94.4%) showed complete bony union. The mean final visual analog scale pain score was 1.1; University of California, Los Angeles score, 31.3; American Shoulder and Elbow Surgeons score, 88.6; and subjective shoulder value, 88.5%. Four complications were observed: (1) intraoperative coracoid process fracture, (2) nonunion, (3) delayed union, and (4) shoulder stiffness. The case with a coracoid process fracture during coracoid tunnel generation was converted to the K-wire tension band technique. CC stabilization using a suture button device for Neer type IIB lateral clavicle fractures yielded satisfactory radiologic and clinical outcomes. The major advantage of this technique is that implant removal is not required. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.
Wang, Lian; Soe, Nwe Nwe; Sowden, Mark; Xu, Yingqian; Modjeski, Kristina; Baskaran, Padmamalini; Kim, Yeonghwan; Smolock, Elaine M; Morrell, Craig N; Berk, Bradford C
2014-05-05
Cyclophilin A (CyPA) is an important mediator in cardiovascular diseases. It possesses peptidyl-prolyl cis-trans isomerase activity (PPIase) and chaperone functions, which regulate protein folding, intracellular trafficking and reactive oxygen species (ROS) production. Platelet glycoprotein receptor αIIbβ3 integrin activation is the common pathway for platelet activation. It was our objective to understand the mechanism by which CyPA-regulates αIIbβ3 activation in platelets. Mice deficient for CyPA (CyPA-/-) had prolonged tail bleeding time compared to wild-type (WT) controls despite equivalent platelet numbers. In vitro studies revealed that CyPA-/- platelets exhibited dramatically decreased thrombin-induced platelet aggregation. In vivo, formation of occlusive thrombi following FeCl3 injury was also significantly impaired in CyPA-/- mice compared with WT-controls. Furthermore, CyPA deficiency inhibited flow-induced thrombus formation in vitro. Flow cytometry demonstrated that thrombin-induced ROS production and αIIbβ3 activation were reduced in CyPA-/- platelets. Coimmunoprecipitation studies showed ROS-dependent increased association of CyPA and αIIbβ3. This association was dependent upon the PPIase activity of CyPA. Significantly, fibrinogen-platelet binding, platelet spreading and cytoskeleton reorganisation were also altered in CyPA-/- platelets. Moreover, CyPA deficiency prevented thrombin-induced αIIbβ3 and cytoskeleton association. In conclusion, CyPA is an important mediator in platelet function by regulation of αIIbβ3 bidirectionalsignalling through increased ROS production and facilitating interaction between αIIbβ3 and the cell cytoskeleton.
De Luca, Giuseppe; Van't Hof, Arnoud W J; Gibson, C Michael; Cutlip, Donald; Zeymer, Uwe; Noc, Marko; Maioli, Mauro; Zorman, Simona; Gabriel, H Mesquita; Emre, Ayse; Rakowski, Tomasz; Gyongyosi, Maryann; Huber, Kurt; Bellandi, Francesco; Dudek, Dariusz
2015-03-15
Contrasting data have been so far reported on facilitation with glycoprotein IIb-IIIa inhibitors (GpIIbIIIa) in patients who underwent primary percutaneous coronary intervention. However, it has been demonstrated a time-dependent composition of coronary thrombus in ST-segment elevation myocardial infarction, with more platelets in the first hours. Subsequently, the benefits of early administration of GpIIbIIIa may be affected by the time from symptoms onset to GpIIbIIIa, that therefore is the aim of this study. Our population is represented by 814 patients who underwent GpIIbIIIa facilitated primary angioplasty included in the Early glycoprotein IIb-IIIa inhibitors in primary angioplasty database. Patients were divided according to quartiles of time from symptom onset to GpIIbIIIa administration (≤65 minutes; 65 to 100 minutes; 101 to 178 minutes; and >178 minutes). Myocardial perfusion was evaluated by myocardial blush grade and ST-segment resolution. Time from symptoms onset to GpIIbIIIa was linearly associated with hypertension, diabetes, hypercholesterolemia, and previous myocardial infarction but inversely associated with smoking. Abciximab was more often administrated later from symptoms onset. Time from symptoms onset to GpIIbIIIa was significantly associated with the rate of preprocedural recanalization (thrombolysis in myocardial infarction [TIMI] 2 to 3; p Time to GpIIbIIIa had a significant impact on mortality (hazard ratio [95% confidence interval] 1.46 [1.11 to 1.92], p = 0.007) that was confirmed after correction for baseline confounding factors (adjusted hazard ratio [95% confidence interval] 1.41 [1.02 to 2.21], p = 0.042). In conclusion, this study showed that in patients who underwent primary angioplasty with upstream GpIIbIIIa, time from symptoms onset to GpIIbIIIa strongly impacts on preprocedural recanalization, distal embolization, myocardial perfusion, and long-term survival.
Ahmed, Kamran A; Wilder, Richard B
2015-01-01
To evaluate post-orchiectomy utilization of radiation therapy (RT) versus other management approaches in stage IIA and IIB testicular seminoma patients. Two hundred and forty-one patients with stage IIA and IIB testicular seminoma were identified between 1988 and 2003 using the Surveillance, Epidemiology, and End Results (SEER) database. Median follow-up was 10 years. Patients with stage IIA disease underwent RT more frequently than those with stage IIB disease (72 % vs. 46 %, respectively; P seminoma.
Flow and transport at the Las Cruces trench site: Experiment IIb
Energy Technology Data Exchange (ETDEWEB)
Vinson, J.; Hills, R.G. [New Mexico State Univ., Las Cruces, NM (United States); Wierenga, P.J.; Young, M.H. [Arizona Univ., Tucson, AZ (United States). Dept. of Soil and Water Science
1997-07-01
The US Nuclear Regulatory Commission (NRC) has been directed by Congress in the Low Level Waste Policy Act of 1980 to develop regulatory guidance and assist the individual states and compacts in siting and assessing future low level radioactive waste (LLW) disposal facilities. Three water flow and solute transport experiments were performed as part of a comprehensive field trench study near Las Cruces, New Mexico to test deterministic and stochastic models of vadose zone flow and transport. This report presents partial results from the third experiment (experiment IIb). Experiments IIa and b were conducted on the North side of the trench, on a plot 1.22 m wide by 12 m long, perpendicular to the trench. The area was drip irrigated during two time periods with water containing a variety of tracers. The advance of the water front during the two irrigation episodes was measured with tensiometers and neutron probes. Solute front positions were determined from soil solution sampling through suction samplers and from disturbed sampling. The results from experiment IIb show predominantly downward water movement through the layered unsaturated soil, as evidenced from neutron probe data and gravimetric sampling. Tritium plumes were only half as deep and half as wide as the water plumes at 310 days after the beginning of experiment IIb. Chromium, applied as Cr(VI), moved a readily as, and similar to tritium, but there was a loss of mass due to reduction of Cr(VI) to Cr(III). Chloride and nitrate, initially present at high concentrations in the soil solution, were displaced by the low concentration irrigation water, resulting in chloride and nitrate concentration distributions that looked like negative images of the tritium distributions. The extensive data presented should serve well as a data base for model testing.
Maeda, K; Milisavljevic, D; Folatelli, G; Drout, M R; Kuncarayakti, H; Margutti, R; Kamble, A; Soderberg, A; Tanaka, M; Kawabata, M; Kawabata, K S; Yamanaka, M; Nomoto, K; Kim, J H; Simon, J D; Phillips, M M; Parrent, J; Nakaoka, T; Moriya, T J; Suzuki, A; Takaki, K; Ishigaki, M; Sakon, I; Tajitsu, A; Iye, M
2015-01-01
We report the late-time evolution of Type IIb Supernova (SN IIb) 2013df. SN 2013df showed a dramatic change in its spectral features at ~1 year after the explosion. Early on it showed typical characteristics shared by SNe IIb/Ib/Ic dominated by metal emission lines, while later on it was dominated by broad and flat-topped Halpha and He I emissions. The late-time spectra are strikingly similar to SN IIb 1993J, which is the only previous example clearly showing the same transition. This late-time evolution is fully explained by a change in the energy input from the 56Co decay to the interaction between the SN ejecta and dense circumstellar matter (CSM). The mass loss rate is derived to be (~5.4 +- 3.2) x 10^{-5} Msun/yr (for the wind velocity of ~20 km/s, similar to SN 1993J but larger than SN IIb 2011dh by an order of magnitude. The striking similarity between SNe 2013df and 1993J in the (candidate) progenitors and the CSM environments, and the contrast in these natures to SN 2011dh, infer that there is a link...
On the absence of BPS preonic solutions in IIA and IIB supergravities
Bandos, I A; de Azcárraga, J A; Azcarraga, Jose A. de; Bandos, Igor A.; Varela, Oscar
2006-01-01
We consider the present absence of 31 out of 32 supersymmetric solutions in supergravity i.e., of solutions describing BPS preons. A recent result indicates that (bosonic) BPS preonic solutions do not exist in type IIB supergravity. We reconsider this analysis by using the G-frame method, extend it to the IIA supergravity case, and show that there are no (bosonic) preonic solutions for type IIA either. For the classical D=11 supergravity no conclusion can be drawn yet, although the negative IIA results permit establishing the conditions that preonic solutions would have to satisfy. For supergravities with `stringy' corrections, the existence of BPS preonic solutions remains fully open.
Warping the Kähler potential of F-theory/IIB flux compactifications
Energy Technology Data Exchange (ETDEWEB)
Martucci, Luca [Dipartimento di Fisica ed Astronomia “Galileo Galilei' , Università di Padova,and INFN - Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy)
2015-03-13
We identify the low-energy Kähler potential of warped F-theory/IIB flux compactifications whose light spectrum includes universal, Kähler, axionic and mobile D3-brane moduli. The derivation is based on four-dimensional local superconformal symmetry and holomorphy of brane instanton contributions and it reproduces and generalises previous partial results. We compute the resulting kinetic terms, which show their explicit dependence on the warping. The Kähler potential satisfies the no-scale condition and produces, at leading order in the large volume expansion, a specific correction to the unwarped Kähler potential.
Prognostic and predictive value of YKL-40 in stage IIB-III melanoma
DEFF Research Database (Denmark)
Krogh, Merete; Christensen, Ib; Bouwhuis, Marna
2016-01-01
This study investigates the prognostic and predictive value of YKL-40 in stage IIB-III melanoma patients who were randomized to adjuvant interferon α-2b (IFN) or observation. Serum YKL-40 was determined postoperatively in patients from the Nordic IFN Trial (n=602), EORTC 18952 (n=246), and EORTC...... 18991 (n=386) (EORTC, European Organisation for Research and Treatment of Cancer). YKL-40 protein expression was determined in 300 tissue sections of primary melanoma or lymph node metastases from 204 Danish patients from the Nordic IFN Trial. Multivariate Cox analysis (including sex, age, stage...
A search for AdS5 X S2 IIB supergravity solutions dual to N = 2 SCFTs
Colgáin, Eoin Ó
2011-01-01
We present a systematic search for Type IIB supergravity solutions whose spacetimes include AdS5 and S2 factors, which would be candidate duals to N = 2 four-dimensional Superconformal field theories. The candidate solutions encode the SU(2) R-symmetry geometrically on the S2 and an additional Killing vector generates the U(1) R-symmetry. By analysing the Killing spinor equations we show that no such solutions exist. This suggests that, if Type IIB backgrounds dual to N = 2 SCFTs exist, the SU(2) R-symmetry is realised non-geometrically. Finally, we also show that, in the context of both N = 1 and N = 2 Type IIB backgrounds with an AdS5 factor, the only candidate U(1) R-symmetry Killing vector directions are the ones that appear for generic values of the Killing spinors; no further Killing vectors exist for special values of the Killing spinors.
Mattheij, Nadine J A; Swieringa, Frauke; Mastenbroek, Tom G; Berny-Lang, Michelle A; May, Frauke; Baaten, Constance C F M J; van der Meijden, Paola E J; Henskens, Yvonne M C; Beckers, Erik A M; Suylen, Dennis P L; Nolte, Marc W; Hackeng, Tilman M; McCarty, Owen J T; Heemskerk, Johan W M; Cosemans, Judith M E M
2016-04-01
Coated platelets, formed by collagen and thrombin activation, have been characterized in different ways: i) by the formation of a protein coat of α-granular proteins; ii) by exposure of procoagulant phosphatidylserine; or iii) by high fibrinogen binding. Yet, their functional role has remained unclear. Here we used a novel transglutaminase probe, Rhod-A14, to identify a subpopulation of platelets with a cross-linked protein coat, and compared this with other platelet subpopulations using a panel of functional assays. Platelet stimulation with convulxin/thrombin resulted in initial integrin α(IIb)β3 activation, the appearance of a platelet population with high fibrinogen binding, (independently of active integrins, but dependent on the presence of thrombin) followed by phosphatidylserine exposure and binding of coagulation factors Va and Xa. A subpopulation of phosphatidylserine-exposing platelets bound Rhod-A14 both in suspension and in thrombi generated on a collagen surface. In suspension, high fibrinogen and Rhod-A14 binding were antagonized by combined inhibition of transglutaminase activity and integrin α(IIb)β3 Markedly, in thrombi from mice deficient in transglutaminase factor XIII, platelet-driven fibrin formation and Rhod-A14 binding were abolished by blockage of integrin α(IIb)β3. Vice versa, star-like fibrin formation from platelets of a patient with deficiency in α(IIb)β3(Glanzmann thrombasthenia) was abolished upon blockage of transglutaminase activity. We conclude that coated platelets, with initial α(IIb)β3 activation and high fibrinogen binding, form a subpopulation of phosphatidylserine-exposing platelets, and function in platelet-dependent star-like fibrin fiber formation via transglutaminase factor XIII and integrin α(IIb)β3.
Exact half-BPS type IIB interface solutions I: local solution and supersymmetric Janus
Energy Technology Data Exchange (ETDEWEB)
D' Hoker, Eric; Estes, John; Gutperle, Michael [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
2007-06-15
The complete Type IIB supergravity solutions with 16 supersymmetries are obtained on the manifold AdS{sub 4} x S{sup 2} x S{sup 2} x {sigma} with SO(2, 3) x SO(3) x SO(3) symmetry in terms of two holomorphic functions on a Riemann surface {sigma}, which generally has a boundary. This is achieved by reducing the BPS equations using the above symmetry requirements, proving that all solutions of the BPS equations solve the full Type IIB supergravity field equations, mapping the BPS equations onto a new integrable system akin to the Liouville and Sine-Gordon theories, and mapping this integrable system to a linear equation which can be solved exactly. Amongst the infinite class of solutions, a non-singular Janus solution is identified which provides the AdS/CFT dual of the maximally supersymmetric Yang-Mills interface theory discovered recently. The construction of general classes of globally non-singular solutions, including fully back-reacted AdS{sub 5} x S{sup 5} and supersymmetric Janus doped with D5 and/or NS5 branes, is deferred to a companion paper.
Topological charges in SL(2,R) covariant massive 11-dimensional and Type IIB SUGRA
Callister, Andrew K
2009-01-01
In this paper we construct closed expressions that correspond to the topological charges of the various 1/2-BPS states of the maximal 10 and 11-dimensional supergravity theories. These expressions are related to the structure of the SUSY algebras in curved spacetimes. We mainly focus on IIB SUGRA and 11-dimensional SUGRA in a double M9-brane background, with an emphasis on the SL(2,R) multiplet structure of the charges and how these map between theories. This includes the charges corresponding to the multiplets of 7- and 9-branes in IIB. We find that examining the possible multiplet structures of the charges provides another tool for exploring the spectrum of BPS states that appear in these theories. As a prerequisite to constructing the charges we determine the field equations and multiplet structure of the 11-dimensional gauge potentials, extending previous results on the subject. The massive gauge transformations of the fields are also discussed. We also demonstrate how these massive gauge transformations ...
Topological charges in SL(2,R) covariant massive 11-dimensional and type IIB supergravity
Callister, Andrew K.; Smith, Douglas J.
2009-12-01
In this paper we construct closed expressions that correspond to the topological charges of the various 1/2-BPS states of the maximal 10- and 11-dimensional supergravity theories. These expressions are related to the structure of the supersymmetry algebras in curved spacetimes. We mainly focus on IIB supergravity and 11-dimensional supergravity in a double M9-brane background, with an emphasis on the SL(2,R) multiplet structure of the charges and how these map between theories. This includes the charges corresponding to the multiplets of 7- and 9-branes in IIB. We find that examining the possible multiplet structures of the charges provides another tool for exploring the spectrum of BPS states that appear in these theories. As a prerequisite to constructing the charges we determine the field equations and multiplet structure of the 11-dimensional gauge potentials, extending previous results on the subject. The massive gauge transformations of the fields are also discussed. We also demonstrate how these massive gauge transformations are compatible with the construction of an SL(2,R) covariant kinetic term in the 11-dimensional Kaluza-Klein monopole worldvolume action.
Generalized type IIB supergravity equations and non-Abelian classical r-matrices
Orlando, Domenico; Sakamoto, Jun-ichi; Yoshida, Kentaroh
2016-01-01
We study Yang-Baxter deformations of the $AdS_5 \\times S^5$ superstring with non-Abelian classical $r$-matrices which satisfy the homogeneous classical Yang-Baxter equation (CYBE). By performing a supercoset construction, we can get deformed $AdS_5 \\times S^5$ backgrounds. While this is a new area of research, the current understanding is that Abelian classical $r$-matrices give rise to solutions of type IIB supergravity, while non-Abelian classical $r$-matrices lead to solutions of the generalized supergravity equations. We examine here some examples of non-Abelian classical r-matrices and derive the associated backgrounds explicitly. All of the resulting backgrounds satisfy the generalized equations. For some of them, we derive "T-dualized" backgrounds by adding a linear coordinate dependence to the dilaton and show that these satisfy the usual type IIB supergravity equations. Remarkably, some of the "T-dualized" backgrounds are locally identical to undeformed $AdS_5 \\times S^5$ after an appropriate coordin...
Generalized type IIB supergravity equations and non-Abelian classical r-matrices
Orlando, Domenico; Reffert, Susanne; Sakamoto, Jun-ichi; Yoshida, Kentaroh
2016-11-01
We study Yang-Baxter deformations of the {{AdS}}5× {S}5 superstring with non-Abelian classical r-matrices which satisfy the homogeneous classical Yang-Baxter equation. By performing a supercoset construction, we can get deformed {{AdS}}5× {S}5 backgrounds. While this is a new area of research, the current understanding is that Abelian classical r-matrices give rise to solutions of type IIB supergravity, while non-Abelian classical r-matrices lead to solutions of the generalized supergravity equations. We examine here some examples of non-Abelian classical r-matrices and derive the associated backgrounds explicitly. All of the resulting backgrounds satisfy the generalized equations. For some of them, we derive ‘T-dualized’ backgrounds by adding a linear coordinate dependence to the dilaton and show that these satisfy the usual type IIB supergravity equations. Remarkably, some of the ‘T-dualized’ backgrounds are locally identical to undeformed {{AdS}}5× {S}5 after an appropriate coordinate transformation, but this seems not to be generally the case.
A sufficient condition for de Sitter vacua in type IIB string theory
Energy Technology Data Exchange (ETDEWEB)
Rummel, Markus [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2011-07-15
We derive a sufficient condition for realizing meta-stable de Sitter vacua with small positive cosmological constant within type IIB string theory flux compactifications with spontaneously broken supersymmetry. There are a number of 'lamp post' constructions of de Sitter vacua in type IIB string theory and supergravity. We show that one of them - the method of 'Kaehler uplifting' by F-terms from an interplay between non-perturbative effects and the leading {alpha}'-correction - allows for a more general parametric understanding of the existence of de Sitter vacua. The result is a condition on the values of the flux induced superpotential and the topological data of the Calabi-Yau compactification, which guarantees the existence of a meta-stable de Sitter vacuum if met. Our analysis explicitly includes the stabilization of all moduli, i.e. the Kaehler, dilaton and complex structure moduli, by the interplay of the leading perturbative and non-perturbative effects at parametrically large volume. (orig.)
A likely inverse-Compton emission from the Type IIb SN 2013df
Li, K L
2016-01-01
The inverse-Compton X-ray emission model for supernovae has been well established to explain the X-ray properties of many supernovae for over 30 years. However, no observational case has yet been found to connect the X-rays with the optical lights as they should be. Here, we report the discovery of a hard X-ray source that is associated with a Type II-b supernova. Simultaneous emission enhancements have been found in both the X-ray and optical light curves twenty days after the supernova explosion. While the enhanced X-rays are likely dominated by inverse-Compton scatterings of the supernova's lights from the Type II-b secondary peak, we propose a scenario of a high-speed supernova ejecta colliding with a low-density pre-supernova stellar wind that produces an optically thin and high-temperature electron gas for the Comptonization. The inferred stellar wind mass-loss rate is consistent with that of the supernova progenitor candidate as a yellow supergiant detected by the Hubble Space Telescope, providing an i...
Multi-Wavelength Observations of the Type IIb Supernova 2009mg
Oates, S. R.; Bayless, A. J.; Stritzinger, M. D.; Prichard, T.; Prieto, J. L.; Immler, S.; Brown, P. J.; Breeveld, A. A.; DePasquale, M.; Kuin, N. P. M.; Hamuy, M.; Holland, S. T.; Taddia, F.; Roming, P. W. A.
2012-01-01
We present Swift UVOT and XRT observations, and visual wavelength spectroscopy of the Type IIb supernova (SN) 2009mg, discovered in the Sb galaxy ESO 121-G26. The observational properties of SN 2009mg are compared to the prototype Type IIb SNe 1993J and 2008ax, with which we find many similarities. However,minor differences are discernible including SN 2009mg not exhibiting an initial fast decline or micro-band upturn as observed in the comparison objects, and its rise to maximum is somewhat slower leading to slightly broader light curves. The late-time temporal index of SN 2009mg, determined from 40 days post-explosion, is consistent with the decay rate of SN 1993J, but inconsistent with the decay of Co-56. This suggests leakage of gamma-rays out of the ejecta and a stellar mass on the small side of the mass distribution. Our XRT nondetection provides an upper limit on the mass-loss rate of the progenitor of M less than 1.5 x 10(exp -5) solar mass yr(exp -1). Modelling of the SN light curve indicates a kinetic energy of 0.15 sup +0.02 sub -0.13 x 10(exp 51) erg, an ejecta mass of 0.56 sup+0.10 sub -.26 solar mass and a Ni-56 mass of 0.10 plus or minus 0.01 solar mass.
The Type IIb Supernova 2013df and Its Cool Supergiant Progenitor
Van Dyk, Schuyler D; Fox, Ori D; Cenko, S Bradley; Clubb, Kelsey I; Filippenko, Alexei V; Foley, Ryan J; Miller, Adam A; Smith, Nathan; Kelly, Patrick L; Lee, William H; Ben-Ami, Sagi; Gal-Yam, Avishay
2013-01-01
We have obtained early-time photometry and spectroscopy of Supernova (SN) 2013df in NGC 4414. The SN is clearly of Type IIb, with notable similarities to SN 1993J. From its luminosity at secondary maximum light, it appears that less $^{56}$Ni ($\\lesssim 0.06\\ M_{\\odot}$) was synthesized in the SN 2013df explosion than was the case for the SNe IIb 1993J, 2008ax, and 2011dh. Based on a comparison of the light curves, the SN 2013df progenitor must have been more extended in radius prior to explosion than the progenitor of SN 1993J. The total extinction for SN 2013df is estimated to be $A_V=0.30$ mag. The metallicity at the SN location is likely to be solar. We have conducted Hubble Space Telescope (HST) Target of Opportunity observations of the SN with the Wide Field Camera 3, and from a precise comparison of these new observations to archival HST observations of the host galaxy obtained 14 years prior to explosion, we have identified the progenitor of SN 2013df to be a yellow supergiant, somewhat hotter than a ...
Ultraviolet Spectroscopy of Type IIb Supernovae: Diversity and the Impact of Circumstellar Material
Ben-Ami, Sagi; Gal-Yam, Avishay; Mazzali, Paolo A; Filippenko, Alexei V; Horesh, Assaf; Matheson, Thomas; Modjaz, Maryam; Sauer, Daniel N; Silverman, Jeffrey M; Smith, Nathan; Yaron, Ofer
2014-01-01
We present new Hubble Space Telescope (HST) multi-epoch ultraviolet (UV) spectra of the bright Type IIb SN 2013df, and undertake a comprehensive anal- ysis of the set of four Type IIb supernovae for which HST UV spectra are available (SN 1993J, SN 2001ig, SN 2011dh, and SN 2013df). We find strong diversity in both continuum levels and line features among these objects. We use radiative-transfer models that fit the optical part of the spectrum well, and find that in three of these four events we see a UV continuum flux excess, apparently unaffected by line absorption. We hypothesize that this emission originates above the photosphere, and is related to interaction with circumstel- lar material (CSM) located in close proximity to the SN progenitor. In contrast, the spectra of SN 2001ig are well fit by single-temperature models, display weak continuum and strong reverse-fluorescence features, and are similar to spectra of radioactive 56Ni-dominated Type Ia supernovae. A comparison of the early shock-cooling comp...
SN 2011fu: A type IIb Supernova with a luminous double-peaked light curve
Morales-Garoffolo, A; Bersten, M; Jerkstrand, A; Taubenberger, S; Benetti, S; Cappellaro, E; Kotak, R; Pastorello, A; Bufano, F; Domínguez, R M; Ergon, M; Fraser, M; Gao, X; García, E; Howell, D A; Isern, J; Smartt, S J; Tomasella, L; Valenti, S
2015-01-01
We present optical and near infrared observations of the type IIb supernova (SN) 2011fu from a few days to $\\sim300$ d after explosion. The SN presents a double-peaked light curve (LC) similar to that of SN 1993J, although more luminous and with a longer cooling phase after the primary peak. The spectral evolution is also similar to SN 1993J's, with hydrogen dominating the spectra to $\\sim40$ d, then helium gaining strength, and nebular emission lines appearing from $\\sim60$ d post-explosion. The velocities derived from the P-Cygni absorptions are overall similar to those of other type IIb SNe. We have found a strong similarity between the oxygen and magnesium line profiles at late times, which suggests that these lines are forming at the same location within the ejecta. The hydrodynamical modelling of the pseudo-bolometric LC and the observed photospheric velocities suggest that SN 2011fu was the explosion of an extended star ($\\rm R\\sim450$ R$_\\odot$), in which 1.3 $\\times 10^{51}$ erg of kinetic energy wer...
Analysis of Late--time Light Curves of Type IIb, Ib and Ic Supernovae
Wheeler, J Craig; Clocchiatti, A
2014-01-01
The shape of the light curve peak of radioactive-powered core-collapse "stripped-envelope," supernovae constrains the ejecta mass, nickel mass, and kinetic energy by the brightness and diffusion time for a given opacity and observed expansion velocity. Late-time light curves give constraints on the same parameters, given the gamma-ray opacity. Previous work has shown that the principal light curve peaks for SN IIb with small amounts of hydrogen and for hydrogen/helium-deficient SN Ib/c are often rather similar near maximum light, suggesting similar ejecta masses and kinetic energies, but that late-time light curves show a wide dispersion, suggesting a dispersion in ejecta masses and kinetic energies. It was also shown that SN IIb and SN Ib/c can have very similar late-time light curves, but different ejecta velocities demanding significantly different ejecta masses and kinetic energies. We revisit these topics by collecting and analyzing well-sampled single color and quasi-bolometric light curves from the lit...
Moduli Space of IIB Superstring and SUYM in AdS5 × S5
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
This paper consists of two parts. In part Ⅰ, we interpret the hidden symmetry of the moduli space of IIB superstring on AdS5 × S5 in terms of the chiral embedding in AdS5, which turns out to be the CP3 conformal affine Toda model. We review how the position μ of poles in the Riemann-Hilbert formulation of dressing transformation and the value of loop parameter μ in the vertex operator of affine algebra determine the moduli space of the soliton solutions, which describes the moduli space of the Green-Schwarz superstring. We show also how this affine SU(4) symmetry affinizes the con formal symmetry in the twistor space, and how a soliton string corresponds to a Robinson congruence with twist and dilation spin coefficients μ of twistor. In part H, by extending the dressing symmetric action of IIB string in AdS5 × S5 to the Da brane, we find a gauged WZW action of Higgs Yang-Mills field including the 2-cocycle of axially anomaly. The left and right twistor structures of left and right α-planes glue into an ambitwistor. The symmetry group of Nahm equations is centrally extended to an affine group, thus we explain why the spectral curve is given by affine Toda.
Radiative-transfer models for supernovae IIb/Ib/Ic from binary-star progenitors
Dessart, Luc; Woosley, Stan; Livne, Eli; Waldman, Roni; Yoon, Sung-Chul; Langer, Norbert
2015-01-01
We present 1-D non-Local-Thermodynamic-Equilibrium time-dependent radiative-transfer simulations for supernovae (SNe) of type IIb, Ib, and Ic that result from the terminal explosion of the mass donor in a close-binary system. Here, we select three ejecta with a total kinetic energy of ~1.2e51erg, but characterised by different ejecta masses (2-5Msun), composition, and chemical mixing. The type IIb/Ib models correspond to the progenitors that have retained their He-rich shell at the time of explosion. The type Ic model arises from a progenitor that has lost its helium shell, but retains 0.32Msun of helium in a CO-rich core of 5.11Msun. We discuss their photometric and spectroscopic properties during the first 2-3 months after explosion, and connect these to their progenitor and ejecta properties including chemical stratification. For these three models, Arnett's rule overestimates the 56Ni mass by ~50% while the procedure of Katz et al., based on an energy argument, yields a more reliable estimate. The presenc...
The vitamin D analog ED-71 is a potent regulator of intestinal phosphate absorption and NaPi-IIb.
Brown, Alex J; Zhang, Fanjie; Ritter, Cynthia S
2012-11-01
The vitamin D analog ED-71 [1α,25-dihydroxy-2β-(3-hydroxypropyloxy)vitamin D(3)] has been approved for treatment of osteoporosis in Japan, but its effects on mineral metabolism have not been fully explored. We investigated the actions of ED-71 on phosphate (Pi) absorption and induction of the intestinal sodium/phosphate cotransporters. Oral treatment of vitamin D-deficient rats with ED-71 (20 pmol every other day for 8 d) produced a maximal 8-fold increase in duodenal Pi absorption, measured by the in situ loop method, whereas 1,25-dihyroxyvitamin D(3) [1,25(OH)(2)D(3]), at doses up to 150 pmol, had no effect. This action of ED-71 was attributable to a dramatic 24-fold induction of sodium-dependent Pi transporter type IIb (NaPi-IIb) mRNA in the duodenum; Pit-1 and Pit-2 mRNA levels were not increased. In vitamin D-replete rats, ED-71 treatment (50 pmol) at 72 and 24 h before death increased NaPi-IIb mRNA in the duodenum and jejunum, but not the ileum, whereas 1,25(OH)(2)D(3) at 1000 pmol was ineffective in all segments. Single oral doses of ED-71 increased mouse intestinal NaPi-IIb mRNA and protein between 6 and 24 h. Surprisingly, rat lung NaPi-IIb was not increased by ED-71, despite its coexpression with the vitamin D receptor in alveolar type II cells. However, ED-71 did not induce intestinal NaPi-IIb in vitamin D receptor-ablated mice. The greater potency of ED-71 than 1,25(OH)(2)D(3) on NaPi-IIb appears to be due to much higher and more prolonged levels of ED-71 in the circulation. In summary, ED-71, due to its disparate pharmacokinetics, is a much more potent inducer of intestinal Pi absorption and NaPi-IIb than 1,25(OH)(2)D(3), suggesting a role for this analog in the treatment of Pi-wasting disorders.
Akkerhuis, KM; van den Brand, MJBM; van der Zwaan, C; Suryapranata, H; van der Wieken, LR; Stibbe, J; Hoffmann, J; Baardman, T; Deckers, JW
2001-01-01
Objective-Lefradafiban is the orally active prodrug of fradafiban, a glycoprotein IIb/IIIa receptor antagonist. The present phase II study aimed to determine the dose of lefradafiban that provides 80% blockade of the glycoprotein IIb/IIIa receptors by fradafiban, and to study the pharmacodynamics an
K.M. Akkerhuis (Martijn); M.L. Simoons (Maarten); C. van der Zwaan (Coen); H. Suryapranata (Harry); J. Stibbe (Jeanne); J. Hoffmann; T. Baardman (Taco); M.J.B.M. van den Brand (Marcel); J.W. Deckers (Jaap); L.R. van der Wieken (Ron); H.O.J. Peels
2001-01-01
textabstractOBJECTIVE: Lefradafiban is the orally active prodrug of fradafiban, a glycoprotein IIb/IIIa receptor antagonist. The present phase II study aimed to determine the dose of lefradafiban that provides 80% blockade of the glycoprotein IIb/IIIa receptors by fradafiban, and to study the pharma
Echeverria, Angela; Krajcer, Zvonimir
2016-10-01
Anticoagulant and antiplatelet medications are necessary in peripheral endovascular intervention, but a standardized approach has not yet been established. Glycoprotein IIb/IIIa inhibitor use in endovascular lower extremity interventions decreased overall amputation rates. Glycoprotein IIb/IIIa inhibitor use in endovascular lower extremity interventions increased postprocedural bleeding and complications requiring intervention.
Verdoia, M.; Pergolini, P.; Camaro, C.; Restifo, M.; Rolla, R.; Schaffer, A.; Giovine, G. Di; Marino, P.; Bellomo, G.; Suryapranata, H.; Luca, G. De; Study, G.
2013-01-01
Glycoprotein IIb-IIIa (Gp IIb-IIIa), a fibrinogen receptor located on platelet surface, is a key point in the pathway leading to platelet aggregation. Therefore, great interest has emerged in the last decades on its pharmacological block, both by irreversible binding of abciximab or by competitive
Budnik, Ivan; Shenkman, Boris; Savion, Naphtali
2016-09-01
Effective platelet function requires formation of a physical link between fibrin(ogen), integrin αIIbβ3, and cytoplasmic actin filaments. We investigated the role of the Gαq, Gαi, and Gα12/13 families of heterotrimeric GTP-binding proteins (G proteins) in the assembly of a ligand-αIIbβ3-actin cytoskeleton complex. Selective and combined activation of the G proteins was achieved by using combinations of various platelet agonists and inhibitors. Formation and stability of fibrinogen-αIIbβ3 interaction were evaluated by the extent of platelet aggregation and the rate of eptifibatide-induced platelet disaggregation; association of αIIbβ3 with the cytoskeleton was analyzed by western blot. Formation of the fibrin-αIIbβ3-actin cytoskeleton complex was evaluated by rotational thromboelastometry assay in which clot formation was induced by the mixture of reptilase and factor XIIIa. We demonstrated that involvement of heterotrimeric G proteins in the formation of the ligand-αIIbβ3-cytoskeleton complex depends on whether fibrinogen or fibrin serves as the integrin ligand. Formation of the fibrinogen-αIIbβ3-cytoskeleton complex requires combined activation of at least two G protein pathways while the maximal αIIbβ3-cytoskeleton association and the strongest αIIbβ3-fibrinogen binding supporting irreversible platelet aggregation require combined activation of all three-Gαq, Gαi, and Gα12/13-G protein families. In contrast, formation of the fibrin-αIIbβ3-cytoskeleton complex mediating clot retraction is critically dependent on the activation of the Gαi family, especially on the activation of Gαz.
Mazonakis, Michalis; Berris, Theocharris; Lyraraki, Efrossyni; Damilakis, John
2015-03-01
This study was conducted to calculate the peripheral dose to critical structures and assess the radiation risks from modern radiotherapy for stage IIA/IIB testicular seminoma. A Monte Carlo code was used for treatment simulation on a computational phantom representing an average adult. The initial treatment phase involved anteroposterior and posteroanaterior modified dog-leg fields exposing para-aortic and ipsilateral iliac lymph nodes followed by a cone-down phase for nodal mass irradiation. Peripheral doses were calculated using different modified dog-leg field dimensions and an extended conventional dog-leg portal. The risk models of the BEIR-VII report and ICRP-103 were combined with dosimetric calculations to estimate the probability of developing stochastic effects. Radiotherapy for stage IIA seminoma with a target dose of 30 Gy resulted in a range of 23.0-603.7 mGy to non-targeted peripheral tissues and organs. The corresponding range for treatment of stage IIB disease to a cumulative dose of 36 Gy was 24.2-633.9 mGy. A dose variation of less than 13% was found by altering the field dimensions. Radiotherapy with the conventional instead of the modern modified dog-leg field increased the peripheral dose up to 8.2 times. The calculated heart doses of 589.0-632.9 mGy may increase the risk for developing cardiovascular diseases whereas the testicular dose of more than 231.9 mGy may lead to a temporary infertility. The probability of birth abnormalities in the offspring of cancer survivors was below 0.13% which is much lower than the spontaneous mutation rate. Abdominoplevic irradiation may increase the lifetime intrinsic risk for the induction of secondary malignancies by 0.6-3.9% depending upon the site of interest, patient’s age and tumor dose. Radiotherapy for stage IIA/IIB seminoma with restricted fields and low doses is associated with an increased morbidity. These data may allow the definition of a risk-adapted follow-up scheme for long
Nonperturbative type IIB model building in the F-theory framework
Energy Technology Data Exchange (ETDEWEB)
Jurke, Benjamin Helmut Friedrich
2011-02-28
This dissertation is concerned with the topic of non-perturbative string theory, which is generally considered to be the most promising approach to a consistent description of quantum gravity. The five known 10-dimensional perturbative string theories are all interconnected by numerous dualities, such that an underlying non-perturbative 11-dimensional theory, called M-theory, is postulated. Due to several technical obstacles, little is known about the fundamental objects in this theory. There exists an alternative non-perturbative description to type IIB string theory, namely F-theory. Here the SL(2;Z) self-duality of IIB theory is geometrized in the form of an elliptic fibration over the space-time. Moreover, higher-dimensional objects like 7-branes are included via singularities into the geometric picture. This formally elegant description, however, requires significant technical effort for the construction of suitable compactification geometries, as many different aspects necessarily have to be dealt with at the same time. On the other hand, the generation of essential GUT building blocks like certain Yukawa couplings or spinor representations is easier compared to perturbative string theory. The goal of this study is therefore to formulate a unified theory within the framework of F-theory, that satisfies basic phenomenological constraints. Within this thesis, at first E3-brane instantons in type IIB string theory - 4-dimensional objects that are entirely wrapped around the invisible dimensions of space-time - are matched with M5-branes in F-theory. Such objects are of great importance in the generation of critical Yukawa couplings or the stabilization of the free parameters of a theory. Certain properties of M5-branes then allow to derive a new criterion for E3-branes to contribute to the superpotential. In the aftermath of this analysis, several compactification geometries are constructed and checked for basic properties that are relevant for semi
Risk model in stage IB1-IIB cervical cancer with positive node after radical hysterectomy
Directory of Open Access Journals (Sweden)
Chen Z
2016-05-01
Full Text Available Zhilan Chen,1,2,* Kecheng Huang,1,* Zhiyong Lu,1,3 Song Deng,1,4 Jiaqiang Xiong,1 Jia Huang,1 Xiong Li,5 Fangxu Tang,1 Zhihao Wang,6 Haiying Sun,1 Lin Wang,1 Shasha Zhou,1 Xiaoli Wang,1 Yao Jia,1 Ting Hu,1 Juan Gui,7 Dongyi Wan,1 Ding Ma,1 Shuang Li,1 Shixuan Wang11Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Techonology, Wuhan, 2Department of Obstetrics and Gynecology, Wuhan General Hospital of Guangzhou Military Command, Wuhan, 3Hubei Key Laboratory of Embryonic Stem Cell Research, Tai-He Hospital, Hubei University of Medicine, Shiyan, Hubei, 4Department of Obstetrics and Gynecology, University Hospital of Hubei University for Nationalities, Enshi, Hubei, 5Department of Obstetrics and Gynecology, Wuhan Central Hospital, Wuhan, 6Department of Pathology and Pathophysiology, Key Laboratory of Ministry of Education of China for Neurological Disorders, Huazhong University of Science and Techonology, Wuhan, 7Department of Obstetrics and Gynecology, Renmin Hospital, Wuhan University, Wuhan, People’s Republic of China*These authors contributed equally to this workAbstract: The purpose of this study was to identify risk factors in patients with surgically treated node-positive IB1-IIB cervical cancer and to establish a risk model for disease-free survival (DFS and overall survival (OS. A total of 170 patients who underwent radical hysterectomy and bilateral pelvic lymphadenectomy as primary treatment for node-positive International Federation of Gynaecology and Obstetrics (FIGO stage IB1-IIB cervical cancer from January 2002 to December 2008 were retrospectively analyzed. Five published risk models were evaluated in this population. The variables, including common iliac lymph node metastasis and parametrial invasion, were independent predictors of outcome in a multivariate analysis using a Cox regression model. Three distinct prognostic groups (low, intermediate, and high risk
On WZ and RR couplings of BPS branes and their all order α‧ corrections in IIB, IIA
Hatefi, Ehsan
2017-03-01
We compute all three and four point couplings of BPS Dp-branes for all different nonzero p-values on the entire world volume and transverse directions. We start finding out all four point function supersymmetric Wess-Zumino (WZ) actions of one closed string Ramond-Ramond (RR) field with two fermions, either with the same (IIB) or different chirality (IIA) as well as their all order α‧ corrections. The closed form of S-matrices of two closed string RR in both IIB, IIA, including their all order α‧ corrections have also been addressed. Our results confirm that, not only the structures of α‧ corrections but also their coefficients of IIB are quite different from their IIA ones. The S-matrix of an RR and two gauge (scalar) fields and their all order corrections in antisymmetric picture of RR have been carried out as well. Various remarks on the restricted Bianchi identities as well as all order α‧ corrections to all different supersymmetric WZ couplings in both type IIA and IIB superstring theory are also released. Lastly, different singularity structures as well as all order contact terms for all non-vanishing traces in type II have also been constructed.
On WZ and RR Couplings of BPS Branes and their all order $\\alpha'$ Corrections in IIB, IIA
Hatefi, Ehsan
2016-01-01
We compute all three and four point couplings of BPS $D_{p}$-branes for all different nonzero $p$-values on the entire world volume and transverse directions. We start finding out all four point function supersymmetric Wess-Zumino (WZ) actions of one closed string Ramond-Ramond (RR) field with two fermions, either with the same (IIB) or different chirality (IIA) as well as their all order $\\alpha'$ corrections. The closed form of S-matrices of two closed string RR in both IIB, IIA, including their all order $\\alpha'$ corrections have also been addressed. Our results confirm that, not only the structures of $\\alpha'$ corrections but also their coefficients of IIB are quite different from their IIA ones. The S-matrix of an RR and two gauge (scalar) fields and their all order corrections in antisymmetric picture of RR have been carried out as well. Various remarks on the restricted Bianchi identities as well as all order $\\alpha'$ corrections to all different supersymmetric WZ couplings in both type IIA and IIB ...
SN 2011dh: DISCOVERY OF A TYPE IIb SUPERNOVA FROM A COMPACT PROGENITOR IN THE NEARBY GALAXY M51
Energy Technology Data Exchange (ETDEWEB)
Arcavi, Iair; Gal-Yam, Avishay; Yaron, Ofer; Sternberg, Assaf; Rabinak, Itay; Waxman, Eli [Department of Particle Physics and Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Kasliwal, Mansi M.; Quimby, Robert M.; Ofek, Eran O.; Horesh, Assaf; Kulkarni, Shrinivas R. [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Filippenko, Alexei V.; Silverman, Jeffrey M.; Cenko, S. Bradley; Li, Weidong; Bloom, Joshua S.; Nugent, Peter E.; Poznanski, Dovi [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Sullivan, Mark [Department of Physics (Astrophysics), University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom); Gorbikov, Evgeny, E-mail: iair.arcavi@weizmann.ac.il [The Wise Observatory and the Raymond and Beverly Sackler School of Physics and Astronomy, the Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); and others
2011-12-15
On 2011 May 31 UT a supernova (SN) exploded in the nearby galaxy M51 (the Whirlpool Galaxy). We discovered this event using small telescopes equipped with CCD cameras and also detected it with the Palomar Transient Factory survey, rapidly confirming it to be a Type II SN. Here, we present multi-color ultraviolet through infrared photometry which is used to calculate the bolometric luminosity and a series of spectra. Our early-time observations indicate that SN 2011dh resulted from the explosion of a relatively compact progenitor star. Rapid shock-breakout cooling leads to relatively low temperatures in early-time spectra, compared to explosions of red supergiant stars, as well as a rapid early light curve decline. Optical spectra of SN 2011dh are dominated by H lines out to day 10 after explosion, after which He I lines develop. This SN is likely a member of the cIIb (compact IIb) class, with progenitor radius larger than that of SN 2008ax and smaller than the eIIb (extended IIb) SN 1993J progenitor. Our data imply that the object identified in pre-explosion Hubble Space Telescope images at the SN location is possibly a companion to the progenitor or a blended source, and not the progenitor star itself, as its radius ({approx}10{sup 13} cm) would be highly inconsistent with constraints from our post-explosion spectra.
Lee, Dong-Ha; Kim, Hyun-Hong; Lim, Deok Hwi; Kim, Jong-Lae; Park, Hwa-Jin
2015-01-01
In this study, we investigated the effects of cordycepin-enriched (CE)-WIB801C, a n-butanol extract of Cordyceps militaris-hypha on collagen-stimulated platelet aggregation. CE-WIB801C dose dependently inhibited collagen-induced platelet aggregation, and had a synergistic effect together with cordycepin (W-cordycepin) from CE-WIB801C on the inhibition of collagen-induced platelet aggregation. CE-WIB801C and cordycepin stimulated the phosphorylation of VASP (Ser157) and the dephosphorylation of PI3K and Akt, and inhibited the binding of fibrinogen to glycoprotein IIb/IIIa (αIIb/β3) and the release of ATP and serotonin in collagen-induced platelet aggregation. A-kinase inhibitor Rp-8-Br-cAMPS reduced CE-WIB801C-, and cordycepin-increased VASP (Ser157) phosphorylation, and increased CE-WIB801C-, and cordycepin-inhibited the fibrinogen binding to αIIb/β3. Therefore, we demonstrate that CE-WIB801C-, and cordycepin-inhibited fibrinogen binding to αIIb/β3 are due to stimulation of cAMP-dependent phosphorylation of VASP (Ser157), and inhibition of PI3K/Akt phosphorylation. These results strongly indicate that CE-WIB801C and cordycepin may have preventive or therapeutic potential for platelet aggregation-mediated diseases, such as thrombosis, myocardial infarction, atherosclerosis, and ischemic cerebrovascular disease. PMID:25593645
Integrin α(IIb)β₃ exists in an activated state in subjects with elevated plasma homocysteine levels.
LENUS (Irish Health Repository)
McGarrigle, Sarah A
2011-01-01
Elevated levels of plasma homocysteine (Hcy) are an independent risk factor for cardiovascular disease and thrombosis. The molecular basis for this phenomenon is not known but may relate to modification of cell surface thiols. The platelet specific integrin α(IIb)β₃ is a cysteine-rich cell adhesion molecule that plays a critical role in platelet aggregation and adhesion in haemostasis and thrombosis. In this study, we looked for evidence of a homocysteine-induced modification of α(IIb)β₃ using a fluorescently labeled PAC-1 antibody that recognizes the activated conformation of the integrin on the platelet surface. We show that exogenous Hcy (10-100 µM) and homocysteine thiolactone (HcyTL) (10-100 µM) increased PAC-1 binding to platelets in a concentration dependent manner in vitro. In parallel, we show subjects with clinical hyperhomocysteinemia exhibit a greater degree of activation of α(IIb)β₃ compared to age-matched controls. These findings demonstrate that circulating Hcy can modulate the activation state of the platelet integrin α(IIb)β₃, a key player in platelet aggregation and thrombosis.
Core-collapse explosions of Wolf–Rayet stars and the connection to Type IIb/Ib/Ic supernovae
Dessart, L.; Hillier, D.J.; Livne, E.; Yoon, S.C.; Woosley, S.E.; Waldman, R.; Langer, N.
2011-01-01
We present non-Local Thermodynamic Equilibrium (LTE) time-dependent radiative-transfer simulations of supernova (SN) IIb/Ib/Ic spectra and light curves, based on ∼1051 erg pistondriven ejecta, with and without 56Ni, produced from single and binary Wolf–Rayet (WR) stars evolved at solar and sub-solar
LENUS (Irish Health Repository)
2015-01-01
Radial head fracture is the most common type of elbow fracture in adults. It results from a fall on an outstretched hand. However, simultaneous bilateral radial head fractures are extremely rare. We report a case of simultaneous bilateral mason type IIb radial head fractures in a young female, which was treated nonoperatively with excellent results
2017-09-28
Cervical Adenocarcinoma; Cervical Adenosquamous Carcinoma; Cervical Squamous Cell Carcinoma, Not Otherwise Specified; Positive Para-Aortic Lymph Node; Positive Pelvic Lymph Node; Stage IB2 Cervical Cancer; Stage II Cervical Cancer; Stage IIA Cervical Cancer; Stage IIB Cervical Cancer; Stage IIIB Cervical Cancer; Stage IVA Cervical Cancer
Khaspekova, S G; Ziuriaev, I T; Iakushkin, V V; Golubeva, N V; Ruda, M Ia; Mazurov, A V
2011-01-01
Interaction between aggregating activity of platelets and glycoprotein (GP) IIb/IIIa (fibrinogen receptor) content on their surface was investigated in patients with acute coronary syndrome (ACS). Eighty nine ACS patients were included into the study - 69 with and 20 without elevation of ST segment. Blood was collected within the first hour of admission to the clinic (1 day), and then at 3-5 and 8-12 days. All patients received standard antiaggregant therapy - acetylsalicylic acid - ASA (thromboxane A2 synthesis inhibitor) and clopidogrel (ADP receptor antagonist). Platelet aggregation was analyzed at the first time point when patients had already taken ASA but not clopidogrel, and then (3-5 and 8- 12 days) upon combined therapy with both preparations. Aggregation was induced by 5 and 20 uM ADP and measured by turbidimetric method. In comparison with the initial level (1 day, ASA) at days 3-5, i.e. after development of clopidogrel effect, platelet aggregation was decreased by 54 and 40% upon its stimulation with 5 and 20 uM ADP, and was not further changed at days 8-12. GP IIb/IIIa content on platelet surface was determined by binding of 125I-labelled monoclonal antibody CRC64. GP IIb/IIIa number varied from 31100 to 73000 per platelet with the mean level of 48500 +/- 8400 (mean +/- standard deviation). No differences were detected between mean GP IIb/IIIa number at 1, 3-5 and 8-12 days after ACS onset. Upon repeat GP IIb/IIIa measurement coefficient of variation was 6.1% demonstrating the stability of this parameter in each patient. Positive correlation between platelet aggregation and GP IIb/IIIa content was detected at the first day - correlation coefficients (r) 0.425 and 0.470 for 5 and 20 uM ADP (n=57, p0.05). These results indicates that variations of GP IIb/IIIa content affect platelet aggregating activity within first hours of ACS upon ASA treatment. However after saturation with clopidogrel this factor has no significant influence on platelet aggregation
A review of the microscopic modeling of the 5-dim. black hole of IIB string theory
Indian Academy of Sciences (India)
Spenta R Wadia
2001-01-01
We review the theory of the microscopic modeling of the 5-dim. black hole of type IIB string theory in terms of the 1-5 brane system. A detailed discussion of the low energy effective Lagrangian of the brane system is presented and the black hole micro-states are identiﬁed. These considerations are valid in the strong coupling regime of supergravity due to the non-renormalization of the low energy dynamics in this model. Using Maldacena duality and standard statistical mechanics methods one can account for black hole thermodynamics and calculate the absorption cross section and the Hawking radiation rates. Hence, at least in the case of this model black hole, since we can account for black hole properties within a unitary theory, there is no information paradox.
Higgins, Melanie A; Hamilton, Aileen M; Boraston, Alisdair B
2017-05-01
Streptococcus pneumoniae harbors a significant number of transporters, including phosphotransferase (PTS) systems, allowing the bacterium to utilize a number of different carbohydrates for metabolic and other purposes. The genes encoding for one PTS transport system in particular (EII(fuc) ) are found within a fucose utilization operon in S. pneumoniae TIGR4. Here, we report the three-dimensional structures of IIA(fuc) and IIB(fuc) providing evidence that this PTS system belongs to the EII(man) family. Additionally, the predicted metabolic pathway for this distinctive fucose utilization system suggests that EII(fuc) transports the H-disaccharide blood group antigen, which would represent a novel PTS transporter specificity. Proteins 2017; 85:963-968. © 2016 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
ANTIMETASTATIC EFFECT OF INTEGRIN IIb/IIIa INHIBITORS ON SALIVARY ADENOID CYSTIC CARCINOMA
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Objectives: To investigate the relation between metastatic potential of salivary adenoid cystic carcinoma (SACC) and tumor cell-platelet adhesion, and the antimetastatic effect of integrin IIb/IIIa inhibitor on SACC. Methods: Tumor cell-platelet adhesion of highly metastatic SACC-LM, non-highly metastatic SACC-83 and effect of aspirin, arginine-aspartate (RD), magnesium acetylsalicylate on adhesion were studied in vitro. Antimetastafic effect of aspirin, RD, magnesium acetysalicylate on experimental metastasis of SACC was observed in vivo. Results: The tumor cell-platelet adhesion was stronger in SACC-LM than in SACC-83. Aspirin, RD and magnesium acetylsalicylate could inhibit the adhesion of SACC-LM at the concentration of 1, 5 and 25 mg/ml. RD can inhibit experimental metastasis of SACC. Conclusion: Metastasis of SACC is related to platelet-tumor cell adhesion, RD could inhibit metastasis of SACC.
XMM-Newton and Swift observations of the Type IIb SN 2011dh in Messier 51
Campana, Sergio
2012-01-01
The Type IIb SN 2011dh exploded in the nearby galaxy M51 (the Whirlpool Galaxy) and provides us with one of the best laboratory to study early high energy emission from SNe. We give here a comprehensive view of the X-ray properties of SN 2011dh from the analyses of two pointed XMM-Newton early observations as well as of the full Swift X-ray Telescope (XRT) dataset (163 ks). Due to the high XMM-Newton throughput, we were able to satisfactorily fit the X-ray spectrum with two hot diffuse gas components including an additional absorption component to our Galaxy. A power law model provided a worse description of the data. In addition, the early Swift XRT light curve hints of a flux excess at early times (< 3 d), consistent with the adiabatic cooling of stellar's photosphere a few days after the shock breakout.
XMM-Newton and Swift observations of the Type IIb supernova 2011dh in Messier 51
Campana, Sergio; Immler, Stefan
2012-11-01
The Type IIb supernova (SN) 2011dh exploded in the nearby galaxy M51 (the Whirlpool galaxy) and provides us with one of the best laboratories to study early high-energy emission from SNe. We give here a comprehensive view of the X-ray properties of SN 2011dh from the analyses of two pointed XMM-Newton early observations as well as the full Swift X-ray Telescope (XRT) data set (163 ks). Due to the high XMM-Newton throughput, we were able to satisfactorily fit the X-ray spectrum with two hot diffuse gas components including an additional absorption component to our Galaxy. A power-law model provided a worse description of the data. In addition, the early Swift XRT light curve hints of a flux excess at early times (≲3 d), consistent with the adiabatic cooling of stellar's photosphere a few days after the shock breakout.
Measurements on irradiated L1 sensor prototypes for the D0 Run IIb silicon detector project
Energy Technology Data Exchange (ETDEWEB)
Ahsan, M.; Bolton, T.; Carnes, K.; /Kansas State U.; Demarteau, M.; /Fermilab; Demina, R.; /Rochester U.; Gray, T.; /Kansas State U.; Korjenevski, S.; /Rochester U.; Lehner, F.; /Zurich U.; Lipton, R.; Mao, H.S.; /Fermilab; McCarthy, R.; /SUNY, Stony Brook /Kansas State U. /Fermilab
2010-01-01
We report on irradiation studies of Hamamatsu prototype silicon microstrip detectors for layer 1 of the D0 upgrade project for Run IIb. The irradiation was carried out with 10 MeV protons up to proton fluence of 10{sup 14} p/cm{sup 2} at the J.R. Macdonald Laboratory, Manhatten, KS. The flux calibration was carefully checked using different dose normalization techniques. The results based on the obtained sensor leakage currents after irradiation show that the NIEL scaling hypothesis for low energy protons has to be applied with great care. We observe 30-40% less radiation damage in silicon for 10 MeV proton exposure than is expected from the predicted NIEL scaling.
AdS$_5$ vacua from type IIB supergravity on $T^{1,1}$
Louis, Jan
2016-01-01
We study maximally supersymmetric Anti-de Sitter backgrounds in consistent N=2 truncations of type IIB supergravity compactified on the Sasaki-Einstein manifold $T^{1,1}$. In particular, we focus on truncations that contain fields coming from the nontrivial second and third cohomology forms on $T^{1,1}$. These give rise to N=2 supergravity coupled to two vector- and two hypermultiplets (Betti-vector truncation) or one vector- and three hypermultiplets (Betti-hyper truncation), respectively. We find that both truncations admit AdS$_5$ backgrounds with the gauge group always being broken but containing at least an $U(1)_R$ factor. Moreover, in both cases we show that the moduli space of AdS vacua is nontrivial and of maximal dimension. Finally, we explicitly compute the metrics on these moduli spaces.
Fiorin, F; Steffan, A; Pradella, P; Bizzaro, N; Potenza, R; De Angelis, V
1998-08-01
EDTA-dependent pseudothrombocytopenia (PTCP) consists of an inappropriate low platelet count caused by autoantibodies present in the serum samples reacting with platelets only in EDTA-anticoagulated blood. By using immunoprecipitation and Western blot techniques, we studied the immunochemical specificity of platelet agglutinating autoantibodies in the serum samples of 10 patients with PTCP. Furthermore, to evaluate a possible role of PTCP-associated IgG autoantibodies in increased platelet turnover, we assayed the plasma glycocalicin (GC) level and calculated the GC index for every patient. Our results provide direct evidence that an epitope located on platelet membrane glycoprotein IIb is recognized by PTCP-associated IgG antibodies; moreover GC levels in patients with EDTA-dependent PTCP were similar to control levels, thus excluding an increased platelet turnover. We conclude that antiplatelet antibodies directed against platelet cryptantigens are unlikely to have a major role in the increased removal of cells from circulation.
Displacements and stress distribution in D0 Run IIb stave due to CTE mismatches
Energy Technology Data Exchange (ETDEWEB)
Lanfranfo, Giobatta; Fast, James; /Fermilab
2001-07-01
A possible D0 Run IIb stave design currently under study is characterized by an outer carbon fiber stiffening shell with the silicon detectors mounted internally and a single central cooling line running between them; in this paper the stave will be analyzed for thermal compatibility since the different coefficient of thermal expansion in the materials may cause unpredictable stresses and strains in the structure. A simplified stave section has been modeled with finite elements for different materials configurations and the vertical and longitudinal displacements induced by the thermal gradient, together with the related stresses, have been computed. Finally, once selected the most suitable material combination, a more realistic model has been created in order to study the influence of the hybrid location along the ladders.
Inhibition of class IIb histone deacetylase significantly improves cloning efficiency in mice.
Ono, Tetsuo; Li, Chong; Mizutani, Eiji; Terashita, Yukari; Yamagata, Kazuo; Wakayama, Teruhiko
2010-12-01
Since the first mouse clone was produced by somatic cell nuclear transfer, the success rate of cloning in mice has been extremely low. Some histone deacetylase inhibitors, such as trichostatin A and scriptaid, have improved the full-term development of mouse clones significantly, but the mechanisms allowing for this are unclear. Here, we found that two other specific inhibitors, suberoylanilide hydroxamic acid and oxamflatin, could also reduce the rate of apoptosis in blastocysts, improve the full-term development of cloned mice, and increase establishment of nuclear transfer-generated embryonic stem cell lines significantly without leading to obvious abnormalities. However, another inhibitor, valproic acid, could not improve cloning efficiency. Suberoylanilide hydroxamic acid, oxamflatin, trichostatin A, and scriptaid are inhibitors for classes I and IIa/b histone deacetylase, whereas valproic acid is an inhibitor for classes I and IIa, suggesting that inhibiting class IIb histone deacetylase is an important step for reprogramming mouse cloning efficiency.
Directory of Open Access Journals (Sweden)
Kulski Jerzy K
2006-12-01
Full Text Available Abstract Background The quail and chicken major histocompatibility complex (Mhc genomic regions have a similar overall organization but differ markedly in that the quail has an expanded number of duplicated class I, class IIB, natural killer (NK-receptor-like, lectin-like and BG genes. Therefore, the elucidation of genetic factors that contribute to the greater Mhc diversity in the quail would help to establish it as a model experimental animal in the investigation of avian Mhc associated diseases. Aims and approaches The main aim here was to characterize the genetic and genomic features of the transcribed major quail MhcIIB (CojaIIB region that is located between the Tapasin and BRD2 genes, and to compare our findings to the available information for the chicken MhcIIB (BLB. We used four approaches in the study of the quail MhcIIB region, (1 haplotype analyses with polymorphic loci, (2 cloning and sequencing of the RT-PCR CojaIIB products from individuals with different haplotypes, (3 genomic sequencing of the CojaIIB region from the individuals with the different haplotypes, and (4 phylogenetic and duplication analysis to explain the variability of the region between the quail and the chicken. Results Our results show that the Tapasin-BRD2 segment of the quail Mhc is highly variable in length and in gene transcription intensity and content. Haplotypic sequences were found to vary in length between 4 to 11 kb. Tapasin-BRD2 segments contain one or two major transcribed CojaIIBs that were probably generated by segmental duplications involving c-type lectin-like genes and NK receptor-like genes, gene fusions between two CojaIIBs and transpositions between the major and minor CojaIIB segments. The relative evolutionary speed for generating the MhcIIBs genomic structures from the ancestral BLB2 was estimated to be two times faster in the quail than in the chicken after their separation from a common ancestor. Four types of genomic rearrangement
ULTRAVIOLET SPECTROSCOPY OF TYPE IIB SUPERNOVAE: DIVERSITY AND THE IMPACT OF CIRCUMSTELLAR MATERIAL
Energy Technology Data Exchange (ETDEWEB)
Ben-Ami, Sagi [Smithsonian Astrophysical Observatory, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Hachinger, Stephan; Mazzali, Paolo A. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Gal-Yam, Avishay; Horesh, Assaf; Yaron, Ofer [Department of Particle Physics and Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Matheson, Thomas [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Modjaz, Maryam [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, Room 529, New York, NY 10003 (United States); Sauer, Daniel N. [Department of Astronomy, Stockholm University, Albanova University Center, SE-106 91 Stockholm (Sweden); Silverman, Jeffrey M. [Department of Astronomy, University of Texas, Austin, TX 78712 (United States); Smith, Nathan, E-mail: sbenami@cfa.harvard.edu [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
2015-04-10
We present new Hubble Space Telescope (HST) multi-epoch ultraviolet (UV) spectra of the bright Type IIb SN 2013df, and undertake a comprehensive analysis of the set of four SNe IIb for which HST UV spectra are available (SN 1993J, SN 2001ig, SN 2011dh, and SN 2013df). We find strong diversity in both continuum levels and line features among these objects. We use radiative-transfer models that fit the optical part of the spectrum well, and find that in three of these four events we see a UV continuum flux excess, apparently unaffected by line absorption. We hypothesize that this emission originates above the photosphere, and is related to interaction with circumstellar material (CSM) located in close proximity to the SN progenitor. In contrast, the spectra of SN 2001ig are well fit by single-temperature models, display weak continuum and strong reverse-fluorescence features, and are similar to spectra of radioactive {sup 56}Ni-dominated SNe Ia. A comparison of the early shock-cooling components in the observed light curves with the UV continuum levels which we assume trace the strength of CSM interaction suggests that events with slower cooling have stronger CSM emission. The radio emission from events having a prominent UV excess is perhaps consistent with slower blast-wave velocities, as expected if the explosion shock was slowed down by the CSM that is also responsible for the strong UV, but this connection is currently speculative as it is based on only a few events.
The type IIb supernova 2013df and its cool supergiant progenitor
Energy Technology Data Exchange (ETDEWEB)
Van Dyk, Schuyler D. [Spitzer Science Center/Caltech, Mail Code 220-6, Pasadena, CA 91125 (United States); Zheng, WeiKang; Fox, Ori D.; Clubb, Kelsey I.; Filippenko, Alexei V.; Kelly, Patrick L. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Miller, Adam A. [Jet Propulsion Laboratory, MS 169-506, Pasadena, CA 91109 (United States); Smith, Nathan [Steward Observatory, University of Arizona, Tucson, AZ 85720 (United States); Lee, William H. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70-264, Cd. Universitaria, México DF 04510 (Mexico); Ben-Ami, Sagi; Gal-Yam, Avishay, E-mail: vandyk@ipac.caltech.edu [Benoziyo Center for Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel)
2014-02-01
We have obtained early-time photometry and spectroscopy of supernova (SN) 2013df in NGC 4414. The SN is clearly of Type IIb, with notable similarities to SN 1993J. From its luminosity at secondary maximum light, it appears that less {sup 56}Ni (≲ 0.06 M {sub ☉}) was synthesized in the SN 2013df explosion than was the case for the SNe IIb 1993J, 2008ax, and 2011dh. Based on a comparison of the light curves, the SN 2013df progenitor must have been more extended in radius prior to explosion than the progenitor of SN 1993J. The total extinction for SN 2013df is estimated to be A{sub V} = 0.30 mag. The metallicity at the SN location is likely to be solar. We have conducted Hubble Space Telescope (HST) Target of Opportunity observations of the SN with the Wide Field Camera 3, and from a precise comparison of these new observations to archival HST observations of the host galaxy obtained 14 yr prior to explosion, we have identified the progenitor of SN 2013df to be a yellow supergiant, somewhat hotter than a red supergiant progenitor for a normal Type II-Plateau SN. From its observed spectral energy distribution, assuming that the light is dominated by one star, the progenitor had effective temperature T {sub eff} = 4250 ± 100 K and a bolometric luminosity L {sub bol} = 10{sup 4.94±0.06} L {sub ☉}. This leads to an effective radius R {sub eff} = 545 ± 65 R {sub ☉}. The star likely had an initial mass in the range of 13-17 M {sub ☉}; however, if it was a member of an interacting binary system, detailed modeling of the system is required to estimate this mass more accurately. The progenitor star of SN 2013df appears to have been relatively similar to the progenitor of SN 1993J.
Bolnick, Daniel I; Snowberg, Lisa K; Caporaso, J Gregory; Lauber, Chris; Knight, Rob; Stutz, William E
2014-10-01
Animals harbour diverse communities of symbiotic bacteria, which differ dramatically among host individuals. This heterogeneity poses an immunological challenge: distinguishing between mutualistic and pathogenic members of diverse and host-specific microbial communities. We propose that Major Histocompatibility class II (MHC) genotypes contribute to recognition and regulation of gut microbes, and thus, MHC polymorphism contributes to microbial variation among hosts. Here, we show that MHC IIb polymorphism is associated with among-individual variation in gut microbiota within a single wild vertebrate population of a small fish, the threespine stickleback. We sampled stickleback from Cedar Lake, on Vancouver Island, and used next-generation sequencing to genotype the sticklebacks' gut microbiota (16S sequencing) and their MHC class IIb exon 2 sequences. The presence of certain MHC motifs was associated with altered relative abundance (increase or decrease) of some microbial Families. The effect sizes are modest and entail a minority of microbial taxa, but these results represent the first indication that MHC genotype may affect gut microbiota composition in natural populations (MHC-microbe associations have also been found in a few studies of lab mice). Surprisingly, these MHC effects were frequently sex-dependent. Finally, hosts with more diverse MHC motifs had less diverse gut microbiota. One implication is that MHC might influence the efficacy of therapeutic strategies to treat dysbiosis-associated disease, including the outcome of microbial transplants between healthy and diseased patients. We also speculate that macroparasite-driven selection on MHC has the potential to indirectly alter the host gut microbiota, and vice versa.
Soft SUSY breaking terms for chiral matter in IIB string compactifications
Energy Technology Data Exchange (ETDEWEB)
Conlon, Joseph P.; Abdussalam, Shehu S.; Quevedo, Fernando; Suruliz, Kerim [DAMTP, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)
2007-01-15
This paper develops the computation of soft supersymmetry breaking terms for chiral D7 matter fields in IIB Calabi-Yau flux compactifications with stabilised moduli. We determine explicit expressions for soft terms for the single-modulus KKLT scenario and the multiple-moduli large volume scenario. In particular we use the chiral matter metrics for Calabi-Yau backgrounds recently computed in hep-th/0609180. These differ from the better understood metrics for non-chiral matter and therefore give a different structure of soft terms. The soft terms take a simple form depending explicitly on the modular weights of the corresponding matter fields. For the large-volume case we find that in the simplest D7 brane configuration, scalar masses, gaugino masses and A-terms are very similar to the dilaton-dominated scenario. Although all soft masses are suppressed by ln (M{sub P}/m{sub 3/2}) compared to the gravitino mass, the anomaly-mediated contributions do not compete, being doubly suppressed and thus subdominant to the gravity-mediated tree-level terms. Soft terms are flavour-universal to leading order in an expansion in inverse Kaehler moduli. They also do not introduce extra CP violating phases to the effective action. We argue that soft term flavour universality should be a property of the large-volume compactifications, and more generally IIB flux models, in which flavour is determined by the complex structure moduli while supersymmetry is broken by the Kaehler moduli. For the simplest large-volume case we run the soft terms to low energies and present some sample spectra and a basic phenomenological analysis.
Selection at the MHC class IIB locus across guppy (Poecilia reticulata) populations.
Fraser, B A; Ramnarine, I W; Neff, B D
2010-02-01
The highly diverse genes of the major histocompatibility complex (MHC) are important in the adaptive immune system and are expected to be under selection from pathogens. Thus, the MHC genes provide an exceptional opportunity to investigate patterns of selection within and across populations. In this study, we analyzed genetic variation at the MHC class IIB gene and six microsatellite loci across 10 populations of guppies (Poecilia reticulata) in the northern range of Trinidad. We found a high level of diversity at the MHC, with a total of 43 alleles in 142 individuals. At the population level, we found that neutral evolution could not fully account for the variability found at the MHC. Instead, we found that MHC F(ST) statistics were lower than F(ST) derived from the microsatellite loci; 33 of 45 population pairwise estimates for the MHC were significantly lower than those for the microsatellite loci, and MHC F(ST) estimates were consistently lower than those predicted by a coalescent model of neutral evolution. These results suggest a similar selection acting across populations, and we discuss the potential roles of directional and balancing selection. At the sequence level, we found evidence for both positive and purifying selection. Furthermore, positive selection was detected within and adjacent to the putative peptide-binding region (PBR) of the MHC. Surprisingly, we also found a purifying selection at two sites within the putative PBR. Overall, our data provide evidence for selection for functional diversity at the MHC class IIB gene at both the population and nucleotide levels of guppy populations.
De Sitter Uplift with Dynamical Susy Breaking
Retolaza, Ander
2015-01-01
We propose the use of D-brane realizations of Dynamical Supersymmetry Breaking (DSB) gauge sectors as sources of uplift in compactifications with moduli stabilization onto de Sitter vacua. This construction is fairly different from the introduction of anti D-branes, yet allows for tunably small contributions to the vacuum energy via their embedding into warped throats. The idea is explicitly exemplified by the embedding of the 1-family $SU(5)$ DSB model in a local warped throat with fluxes, which we discuss in detail in terms of orientifolds of dimer diagrams.
De Sitter uplift with Dynamical Susy Breaking
Retolaza, Ander; Uranga, Angel
2016-04-01
We propose the use of D-brane realizations of Dynamical Supersymmetry Breaking (DSB) gauge sectors as sources of uplift in compactifications with moduli stabilization onto de Sitter vacua. This construction is fairly different from the introduction of anti D-branes, yet allows for tunably small contributions to the vacuum energy via their embedding into warped throats. The idea is explicitly exemplified by the embedding of the 1-family SU(5) DSB model in a local warped throat with fluxes, which we discuss in detail in terms of orientifolds of dimer diagrams.
Directory of Open Access Journals (Sweden)
Kamran A. Ahmed
2015-02-01
Full Text Available Objectives To evaluate post-orchiectomy utilization of radiation therapy (RT versus other management approaches in stage IIA and IIB testicular seminoma patients. Materials and Methods Two hundred and forty-one patients with stage IIA and IIB testicular seminoma were identified between 1988 and 2003 using the Surveillance, Epidemiology, and End Results (SEER database. Results Median follow-up was 10 years. Patients with stage IIA disease underwent RT more frequently than those with stage IIB disease (72% vs. 46%, respectively; P<0.001. There was no significant change in RT utilization for stage IIA or IIB disease between 1988 and 2003 (P = 0.89. Conclusions Between 1988 and 2003, stage IIA patients underwent RT more often than stage IIB patients in the United States. There was no significant change in RT utilization for stage IIA or IIB disease during this time period. Based on reports describing excellent progression-free survival with cisplatin-based chemotherapy, this approach has increased in popularity since 2003 and may eventually become the most popular treatment approach for both stage IIA and IIB testicular seminoma.
Ahmed, Kamran A.; Wilder, Richard B.
2015-01-01
Objectives To evaluate post-orchiectomy utilization of radiation therapy (RT) versus other management approaches in stage IIA and IIB testicular seminoma patients. Materials and Methods Two hundred and forty-one patients with stage IIA and IIB testicular seminoma were identified between 1988 and 2003 using the Surveillance, Epidemiology, and End Results (SEER) database. Results Median follow-up was 10 years. Patients with stage IIA disease underwent RT more frequently than those with stage IIB disease (72% vs. 46%, respectively; Pseminoma. PMID:25928512
Zeng, Lin; Jin, Shouguang
2003-01-01
Pseudomonas aeruginosa harbors a chromosomal aminoglycoside phosphotransferase gene, aph(3′)-IIb, which confers P. aeruginosa resistance to several important aminoglycoside antibiotics, including kanamycin A and B, neomycin B and C, butirosin, and seldomycin F5. The aph(3′)-IIb gene has been found to be regulated by an AraC-type transcriptional regulator (HpaA) encoded by a gene located upstream of the aph(3′)-IIb gene. In the presence of 4-hydroxyphenylacetic acid (4-HPA), HpaA activates the...
ANTIMETASTATIC EFFECT OF INTEGRIN IIb/IIIa INHIBITORS ON SALIVARY ADENOID CYSTIC CARCINOMA
Institute of Scientific and Technical Information of China (English)
LI; Feng-he
2001-01-01
［1］Gasic GJ, Gasic TB, Stewart CC, et al. Antimetastatic effects associated with platelet reduction [J]. Proc Natl Acad Sci 1968; 61:46.［2］Gu YZ, Qiu WL, He RG, et al. An experimental study of the effects of aspirin on the adhesion of salivary adenoid cystic carcinoma cells [J]. Shanghai Stomatol 1999; 8:65.［3］Im SY, Ko HM, Ko JW, et al. Augmentation of tumor metastasis by platelet-activating factor [J]. Cancer Res 1996; 56:2262.［4］Tang DG, Onoda JM, Steinert BW. Phenotypic properties of cultured tumor cells: Integrin IIb/b 3 expression, tumor-cell-induced platelet aggrega-tion, and tumor cell adhesion to endothelium as an important parameters of experimental metastasis [J]. Int J Cancer 1993; 54:338.［5］Oleksowicz L, Mrowiec Z, Schwartz E, et al. Characterization of tumor-induced platelet aggregafion: The role of immunorelated GP IIb/IIIa expression by MCF-7 breast cancer cells [J]. Thromb Rest 1995; 79:261.［6］Nierodzik ML, Klepfish A, Karptkin S, et al. Role of platelet thrombin, integrin IIb-IIIa, fibronectin and von Willebrand factors on tumor adhesion in vitro and metastasis in vivo [J]. Thromb Haemost 1995; 74:282.［7］Guan Xiao-feng, Qiu Wei-liu, He Rong-gen, et al. The selection of a highly pulmonary metastatic cell line of salivary adenoid cystic carcinoma [J]. Chi J Stomatol 1996; 31:74.［8］Bhatti RA, Gadarowski J, Ray P, et al. Potential role of platelet and coagulation factors in the metastasis of prostatic cancer [J]. Invasion Metastasis 1996; 16:49.［9］Li Sheng-lin, Liu Xiu-Ping, Zhang Kui-hua. Establishment of a human salivary adenoid cystic carcinoma cell line and its characteristics [J]. Chi J Stomatol 1990; 25:29.［10］Chang HS, Yang RS, Huang TF. The Arg-Gly-Asp-containing peptide, rhodostomin, inhibits in vitro cell adhesion to extracellular matrices and platelet aggregation caused by Sao-2 human osteosarcoma cells [J]. Br J Cancer 1995; 71:265.［11］Karptkin S, Pearlstein E, Ambrogio C, et al. Role of adhesive
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Achmad F. Kamal
2011-05-01
Full Text Available Background: Extracorporeally irradiated (ECI technique is an alternative of limb salvage procedure in treating osteosarcoma regarding limitation of endoprosthesis and allograft. This study evaluated the outcomes of limb salvage surgery using extracorporeally irradiated (ECI autograft and its correlation with patient’s characteristics.Methods: Retrospective cohort design was performed to study 20 patients with stage IIB osteosarcoma treated by ECI autograft from 1995 to 2008. Survival, local recurrence, metastases, complications, union time and functional score based on Musculoskeletal Tumor Society scoring system-(MSTS were evaluated. Kaplan-Meier method was used to describe survival, local recurrence free survival, and metastases free survival. The correlation among patient’s characteristics that were age, gender, duration, site of tumor size, type of osteosarcoma, SAP (serum alkaline phosphatase level, type of biopsy, and type of Huvos were analyzed by Log rank test. Chi-square test was used to analyze the correlation between MSTS score and patient’s characteristics, local recurrence, metastases, complications.Results: Five-year survival was 54.97 ± 9.8 %, five-year local recurrence free survival was 66.5 ± 7.6%, and five year metastasis-free survival was 57.13 ± 10.04%. Six patients died, five were due to lung metastases and one due to complication of chemotherapy. Three underwent amputation after local recurrence. Kaplan-Meier curve showed that a good type of Huvos (III, IV always gave better survival, local recurrence free survival, and metastases free survival than poor type of Huvos (I,II. Normal SAP level gave better local recurrence free survival compare to increased level of SAP. Mean of union rate was 8.13 months. MSTS mean score was good (70.63% in patients with no evidence of disease. MSTS score was poor in patients with local recurrence (p = 0.025, metastases (p = 0.01, complications (p = 0.03, and the
Gillingham, Mark A F; Béchet, Arnaud; Courtiol, Alexandre; Rendón-Martos, Manuel; Amat, Juan A; Samraoui, Boudjéma; Onmuş, Ortaç; Sommer, Simone; Cézilly, Frank
2017-02-20
Selective pressure from pathogens is thought to shape the allelic diversity of major histocompatibility complex (MHC) genes in vertebrates. In particular, both local adaptation to pathogens and gene flow are thought to explain a large part of the intraspecific variation observed in MHC allelic diversity. To date, however, evidence that adaptation to locally prevalent pathogens maintains MHC variation is limited to species with limited dispersal and, hence, reduced gene flow. On the one hand high gene flow can disrupt local adaptation in species with high dispersal rates, on the other hand such species are much more likely to experience spatial variation in pathogen pressure, suggesting that there may be intense pathogen mediated selection pressure operating across breeding sites in panmictic species. Such pathogen mediated selection pressure operating across breeding sites should therefore be sufficient to maintain high MHC diversity in high dispersing species in the absence of local adaptation mechanisms. We used the Greater Flamingo, Phoenicopterus roseus, a long-lived colonial bird showing a homogeneous genetic structure of neutral markers at the scale of the Mediterranean region, to test the prediction that higher MHC allelic diversity with no population structure should occur in large panmictic populations of long-distance dispersing birds than in other resident species. We assessed the level of allelic diversity at the MHC Class IIB exon 2 from 116 individuals born in four different breeding colonies of Greater Flamingo in the Mediterranean region. We found one of the highest allelic diversity (109 alleles, 2 loci) of any non-passerine avian species investigated so far relative to the number of individuals and loci genotyped. There was no evidence of population structure between the four major Mediterranean breeding colonies. Our results suggest that local adaptation at MHC Class IIB in Greater Flamingos is constrained by high gene flow and high MHC diversity
National Research Council Canada - National Science Library
Nährlich, Lutz; Mainz, Jochen G; Adams, Constantin; Engel, Corinna; Herrmann, Gloria; Icheva, Vanya; Lauer, Josefine; Deppisch, Caroline; Wirth, Andreas; Unger, Katy; Graepler-Mainka, Ute; Hector, Andreas; Heyder, Susanne; Stern, Martin; Döring, Gerd; Gulbins, Erich; Riethmüller, Joachim
2013-01-01
... and infection susceptibility to pulmonary P. aeruginosa in these mice. To test for a beneficial effect of amitriptyline in vivo, we performed a phase IIb randomised, double-blind, placebo-controlled study...
Directory of Open Access Journals (Sweden)
Jens Röther
2015-08-01
Conclusion: Vascular events with the use of IABP are common but in our study, not significantly associated with a higher mortality. Treatment with GP IIb/IIIa-antagonists is associated with a higher risk of vascular events.
Remarks on non-BPS string amplitudes and their all order α' contact interactions in IIB, IIA
Hatefi, Ehsan
2017-03-01
We explore the entire form of S-Matrix elements of a potential C n-1 Ramond-Ramond (RR) form field, a tachyon and two transverse scalar fields on both world volume and transverse directions of type IIB and IIA superstring theories. Apart from string theory can be re-verified in an Effective Field Theory (EFT) by pull-back of branes. To construct the rest of S-matrix elements one needs to first derive restricted world volume (or bulk) Bianchi identities and then discover new EFT couplings in both type IIB and IIA. Finally the presence of commutator of scalar fields inside the exponential of Wess-Zumino action for non-BPS branes has been confirmed as well.
All 1/2 BPS solutions of IIB supergravity with SO(4)xSO(4) isometry
Energy Technology Data Exchange (ETDEWEB)
Liu, James T. [Michigan Center for Theoretical Physics, Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States)], E-mail: jimliu@umich.edu; Sabra, Wafic [Centre for Advanced Mathematical Sciences and Physics Department, American University of Beirut (Lebanon)
2007-12-13
In (hep-th/0409174), Lin, Lunin and Maldacena constructed a set of regular 1/2 BPS geometries in IIB theory. These remarkable 'bubbling AdS' geometries have a natural interpretation as duals of chiral primary operators with weight {delta}=J in N=4 super-Yang-Mills theory. Although these geometries have been assumed to be complete, from a purely supergravity point of view, additional 1/2 BPS configurations may potentially exist with a preferred null isometry. We explore this possibility and prove that the only additional class of 1/2 BPS solutions with SO(4)xSO(4) isometry are the familiar IIB pp-waves.
Pham, Thuy-Trang; Accadbled, Franck; Abid, Abdelaziz; Ibnoulkhatib, Aissa; Bayle-Iniguez, Xavier; Wargny, Matthieu; Sales de Gauzy, Jérôme
2017-07-20
Blount's method is controversial for the treatment of Gartland types IIB and III supracondylar fracture of the humerus (SCFH) in children. The purpose of this study was to evaluate the clinical and radiologic outcomes and the failure and complication rates. All types IIB and III SCFH treated with Blount's method from 2003-2013 were included in this retrospective single-center study. Clinical assessment was performed according to Flynn criteria. Baumann angle, anteversion angle, anterior humeral line, and humeroulnar angle were measured for radiographic assessment. Among 447 children with types IIB and III SCHF, 339 were treated according to Blount's method. There were 173 boys (51%), and the mean age was 6.3 years (1-14 years); 71% were type III. Mean time to surgery was 5.7 hours. According to Flynn criteria, results were satisfactory in 91% of cases. No compartment syndrome was encountered. There were 16 (4.7%) secondary displacements requiring surgical revision. Five (1.9%) children developed a cubitus varus deformity. At latest follow-up, the mean Baumann angle was 74.7° (95% confidence interval, 74.1-75.3), the mean anteversion angle was 39.9° (95% confidence interval, 39.5-40.3), the anterior humeral line was normal in 87.6% of cases, and the mean humeroulnar angle was 8.7°. Blount's method is appropriate to manage types IIB and III SCFH, provided anatomic and stable reduction is obtained. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.
Institute of Scientific and Technical Information of China (English)
Li HUANG; Mian ZHAO; Zhenhua LUO; Hua WU
2016-01-01
The worldwide declines in amphibian populations have largely been caused by infectious fungi and bacteria. Given that vertebrate immunity against these extracellular pathogens is primarily functioned by the major histocompatibility complex (MHC) class II molecules, the characterization and the evolution of amphibian MHC class II genes have attracted increasing attention. The polymorphism of MHC class II genes was found to be correlated with susceptibility to fungal pathogens in many amphibian species, suggesting the importance of studies on MHC class II genes for amphibians. However, such studies on MHC class II gene evolution have rarely been conducted on amphibians in China. In this study, we chose Omei treefrog (Rhacophorus omeimontis), which lived moist environments easy for breeding bacteria, to study the polymorphism of its MHC class II genes and the underlying evolutionary mechanisms. We amplified the entire MHC class IIB exon 2 sequence in the R. omeimontis using newly designed primers. We detected 102 putative alleles in 146 individuals. The number of alleles per individual ranged from one to seven, indicating that there are at least four loci containing MHC class IIB genes in R. omeimontis. The allelic polymorphism estimated from the 102 alleles in R. omeimontis was not high compared to that estimated in other anuran species. No significant gene recombination was detected in the 102 MHC class IIB exon 2 sequences. In contrast, both gene duplication and balancing selection greatly contributed to the variability in MHC class IIB exon 2 sequences of R. omeimontis. This study lays the groundwork for the future researches to comprehensively analyze the evolution of amphibian MHC genes and to assess the role of MHC gene polymorphisms in resistance against extracellular pathogens for amphibians in China.
Directory of Open Access Journals (Sweden)
Daniel K Shanley
Full Text Available Pregnancy-specific glycoproteins (PSGs are immunoglobulin superfamily members encoded by multigene families in rodents and primates. In human pregnancy, PSGs are secreted by the syncytiotrophoblast, a fetal tissue, and reach a concentration of up to 400 ug/ml in the maternal bloodstream at term. Human and mouse PSGs induce release of anti-inflammatory cytokines such as IL-10 and TGFβ1 from monocytes, macrophages, and other cell types, suggesting an immunoregulatory function. RGD tri-peptide motifs in the majority of human PSGs suggest that they may function like snake venom disintegrins, which bind integrins and inhibit interactions with ligands. We noted that human PSG1 has a KGD, rather than an RGD motif. The presence of a KGD in barbourin, a platelet integrin αIIbβ3 antagonist found in snake venom, suggested that PSG1 may be a selective αIIbβ3 ligand. Here we show that human PSG1 binds αIIbβ3 and inhibits the platelet - fibrinogen interaction. Unexpectedly, however, the KGD is not critical as multiple PSG1 domains independently bind and inhibit αIIbβ3 function. Human PSG9 and mouse Psg23 are also inhibitory suggesting conservation of this function across primate and rodent PSG families. Our results suggest that in species with haemochorial placentation, in which maternal blood is in direct contact with fetal trophoblast, the high expression level of PSGs reflects a requirement to antagonise abundant (3 mg/ml fibrinogen in the maternal circulation, which may be necessary to prevent platelet aggregation and thrombosis in the prothrombotic maternal environment of pregnancy.
Ezumi, Y; Takayama, H; Okuma, M
1995-05-19
The major platelet integrin alpha IIb beta 3 (glycoprotein IIb-IIIa) has been implicated in the regulation of tyrosine phosphorylation and dephosphorylation in activated platelets. To investigate the mechanisms of the alpha IIb beta 3-dependent tyrosine dephosphorylation, normal platelets or thrombasthenic platelets lacking alpha IIb beta 3 were stimulated with thrombin and fractionated into Triton X-100-soluble or -insoluble subcellular matrices. We then examined the kinetics of the tyrosine-phosphorylated proteins and distribution of protein-tyrosine phosphatases in these fractions and whole cell lysates. First, alpha IIb beta 3-dependent tyrosine dephosphorylation was recovered mainly in the cytoskeleton with similar kinetics to the whole cell lysate. Second, protein-tyrosine phosphatase (PTP) 1B and its cleaved 42-kDa form were associated with the cytoskeleton in an aggregation-dependent manner, whereas association of PTP1C with the cytoskeleton was regulated differentially both by thrombin stimulation and by alpha IIb beta 3-mediated aggregation. Several calpain inhibitors did not affect either tyrosine phosphorylation and dephosphorylation or relocation of PTP1B, but they did inhibit cleavage of PTP1B. Cytochalasin D blocked relocation of both PTP1B and PTP1C but not PTP1B cleavage. SH-PTP2 was distributed in the other fractions than the cytoskeleton and showed no relocation on thrombin stimulation. Finally, the cytoskeleton-associated PTP1C became tyrosine-phosphorylated in an alpha IIb beta 3-mediated aggregation-dependent manner. Thus, integrin alpha IIb beta 3 was involved differentially in the regulation of PTP1B and PTP1C.
Tsume, Yasuhiro; Igawa, Naoto; Drelich, Adam J; Amidon, Gregory E; Amidon, Gordon L
2017-09-14
The formulation developments and the in vivo assessment of Biopharmaceutical Classification System (BCS) class II drugs are challenging due to their low solubility and high permeability in the human gastrointestinal (GI) tract. Since the GI environment influences the drug dissolution of BCS class II drugs, the human GI characteristics should be incorporated into the in vitro dissolution system to predict bioperformance of BCS class II drugs. An absorptive compartment may be important in dissolution apparatus for BCS class II drugs, especially for bases (BCS IIb) because of high permeability, precipitation and supersaturation. Thus, the in vitro dissolution system with an absorptive compartment may help predicting the in vivo phenomena of BCS class II drugs better than compendial dissolution apparatuses. In this study, an absorptive compartment (a biphasic device) was introduced to a gastrointestinal simulator (GIS). This addition was evaluated if this in vitro system could improve the prediction of in vivo dissolution for BCS class IIb drugs, ketoconazole and raloxifene, and subsequent absorption. The GIS is a practical in vivo predictive tool and exhibited an improved in vivo prediction utilizing the biphasic format and thus a better tool for evaluating the bioperformance of BCS class IIb drugs than compendial apparatuses. Copyright © 2017. Published by Elsevier Inc.
Type IIb Supernova SN 2011dh: Spectra and Photometry from the Ultraviolet to the Near-Infrared
Marion, G H "Howie''; Kirshner, Robert P; Foley, Ryan J; Berlind, Perry; Bieryla, Allyson; Bloom, Joshua S; Calkins, Michael L; Challis, Peter; Chevalier, Roger A; Chornock, Ryan; Culliton, Chris; Curtis, Jason L; Esquerdo, Gilbert A; Everett, Mark E; Falco, Emilio E; France, Kevin; Fransson, Claes; Friedman, Andrew S; Garnavich, Peter; Leibundgut, Bruno; Meyer, Samuel; Smith, Nathan; Soderberg, Alicia M; Sollerman, Jesper; Starr, Dan L; Szklenar, Tamas; Takats, Katalin; Wheeler, J Craig
2013-01-01
We report spectroscopic and photometric observations of the Type IIb SN 2011dh obtained between 4 and 34 days after the estimated date of explosion (May 31.5 UT). These data cover a wide wavelength range from 2000 Angstroms in the ultraviolet (UV) to 2.4 microns in the near-infrared (NIR). NIR spectra reveal helium in the atmosphere 3 days before the B-band maximum and confirm the classification of SN 2011dh as a Type IIb. Optical spectra provide line profiles and velocity measurements of H I, He I, Ca II and Fe II. UV spectra obtained with the Space Telescope Imaging Spectrograph show that the UV flux for SN 2011dh is low compared to other SN IIb. H I features are strong early and weaken during the period of our observations. He I features are first detected eleven days after the explosion and become progressively stronger. For all phases at which He is detected, the hydrogen line-forming region is separated from the helium layer by about 4000 km/s. This velocity gap is consistent with a H-rich shell surroun...
The Prognosis of Patients with Stage Ib-IIb Node-Positive Cervical Carcinoma after Radical Surgery
Institute of Scientific and Technical Information of China (English)
XiCheng; ShumoCai; ZitingLi; MeiqinTang; MuquanXue; RongyuZang
2004-01-01
OBJECTIVE To investigate the influence of positive lymph nodes on the prognosis for patients with stage Ib-IIb cervical carcinoma.METHODS Sixty-six patients with stage Ib-IIb cervical carcinoma who underwent a radical hysterectomy and pelvic lymphadenectomy were analyzed retrospectively. The potential prognostic factors were calculated by the Cox proportional hazard model.RFSULTS The 5-year survival of metastasis was 40.7%. The Coxthe patients with pelvic lymph node proportional hazard model analysis showed that cellular differentiation, the number of positive nodes and adjuvant therapy were independent prognostic factors (PO.05). The 5-year survival of the patients who had no adjuvant therapy (12.6%) was much lower than that(53.7%) of those with adjuvant therapy (P0.05).CONCLUSION The prognosis of patients with stage Ib-IIb node-positive cervical carcinoma who underwent radical surgery was poor. Adjuvant therapy can increase the survival rate, decrease the pelvic recurrence and distant metastasis.
A BINARY PROGENITOR FOR THE TYPE IIb SUPERNOVA 2011dh IN M51
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Benvenuto, Omar G. [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, B1900FWA La Plata (Argentina); Bersten, Melina C.; Nomoto, Ken' ichi, E-mail: obenvenu@fcaglp.unlp.edu.ar, E-mail: melina.bersten@ipmu.jp [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)
2013-01-10
We perform binary stellar evolutionary calculations following the simultaneous evolution of both stars in the system to study a potential progenitor system for the Type IIb supernova 2011dh. Pre-explosion photometry as well as light-curve modeling has provided constraints on the physical properties of the progenitor system. Here, we present a close binary system (CBS) that is compatible with such constraints. The system is formed by stars of solar composition with 16 M {sub Sun} + 10 M {sub Sun} on a circular orbit with an initial period of 125 days. The primary star ends its evolution as a yellow supergiant with a mass of Almost-Equal-To 4 M {sub Sun }, a final hydrogen content of Almost-Equal-To (3-5) Multiplication-Sign 10{sup -3} M {sub Sun }, and with an effective temperature and luminosity in agreement with the Hubble Space Telescope (HST) pre-explosion observations of SN 2011dh. These results are nearly insensitive to the adopted accretion efficiency factor {beta}. At the time of explosion, the companion star has an effective temperature of 22,000-40,000 K, depending on the value of {beta}, and lies near the zero-age main sequence. Considering the uncertainties in the HST pre-SN photometry, the secondary star is only marginally detectable in the bluest observed band. CBSs, as opposed to single stars, provide a natural frame to explain the properties of SN 2011dh.
Radio and X-rays From SN 2013df Enlighten Progenitors of Type IIb Supernovae
Kamble, Atish; Soderberg, Alicia M; Chakraborti, Sayan; Fransson, Claes; Chevalier, Roger; Powell, Diana; Milisavljevic, Dan; Parrent, Jerod; Bietenholz, Michael
2015-01-01
We present radio and X-ray observations of the nearby Type IIb Supernova 2013df in NGC4414 from 10 to 250 days after the explosion. The radio emission showed a peculiar soft-to-hard spectral evolution. We present a model in which inverse Compton cooling of synchrotron emitting electrons can account for the observed spectral and light curve evolution. A significant mass loss rate, $\\dot{M} \\approx 8 \\times 10^{-5}\\,\\rm M_{\\odot}/yr$ for a wind velocity of 10 km/s, is estimated from the detailed modeling of radio and X-ray emission, which are primarily due to synchrotron and bremsstrahlung, respectively. We show that SN 2013df is similar to SN 1993J in various ways. The shock wave speed of SN 2013df was found to be average among the radio supernovae; $v_{sh}/c \\sim 0.07$. We did not find any significant deviation from smooth decline in the light curve of SN 2013df. One of the main results of our self-consistent multiband modeling is the significant deviation from energy equipartition between magnetic fields and...
Higher derivative corrections to near-extremal black holes in type IIB supergravity
Buchel, A
2006-01-01
We discuss string theory alpha' corrections to charged near-extremal black 3-branes/black holes in type IIB supergravity. We find that supersymmetric global AdS_5 x S^5 geometry is not corrected to leading order in alpha', while charged or non-extremal black 3-branes/black hole geometries receive alpha' corrections. Following gauge theory-string theory correspondence the thermodynamics of these geometries is mapped to the thermodynamics of large-n_c N=4 supersymmetric Yang-Mills theory at finite (large) 't Hooft coupling with the U(1)_R-charge chemical potential. We use holographic renormalization to compute the Gibbs free energy and the ADM mass of the near-extremal solutions. The remaining thermodynamic potentials are evaluated enforcing the first law of thermodynamics. We present analytic expressions for the alpha' corrected thermodynamics of black holes in AdS_5 x S^5 and the thermodynamics of charged black 3-branes with identical chemical potentials for [U(1)_R]^3 charges and large (compare to chemical p...
Warped $AdS_6\\times S^2$ in Type IIB supergravity I: Local solutions
D'Hoker, Eric; Karch, Andreas; Uhlemann, Christoph F
2016-01-01
We investigate the existence of solutions with 16 residual supersymmetries to Type IIB supergravity on a space-time of the form $AdS_6 \\times S^2$ warped over a two-dimensional Riemann surface $\\Sigma$. The $SO(2,5) \\times SO(3)$ isometry extends to invariance under the exceptional Lie superalgebra $F(4)$. In the present paper, we construct the general Ansatz compatible with these symmetries, derive the corresponding reduced BPS equations, and obtain their complete local solution in terms of two locally holomorphic functions ${\\cal A}_\\pm$ on $\\Sigma$, subject to certain positivity and regularity conditions. Globally, $({\\cal A}_+, {\\cal A}_-)$ are allowed to be multiple-valued on $\\Sigma$ and be holomorphic sections of a holomorphic bundle over $\\Sigma$ with structure group contained in $SU(1,1) \\times { C}$. Globally regular solutions are expected to provide the near-horizon geometry of $(p,q)$ 5-brane and 7-brane webs which are holographic duals to five-dimensional conformal field theories. A preliminary a...
The Type IIb SN 2011dh - 2 years of observations and modelling of the lightcurves
Ergon, M; Sollerman, J; Elias-Rosa, N; Fransson, C; Fraser, M; Pastorello, A; Kotak, R; Taubenberger, S; Tomasella, L; Valenti, S; Benetti, S; Helou, G; Kasliwal, M M; Maund, J; Smartt, S J; Spyromilio, J
2014-01-01
We present optical and near-infrared (NIR) photometry and spectroscopy as well as modelling of the lightcurves of the Type IIb supernova (SN) 2011dh. Our extensive dataset spans 2 years, and complemented with Spitzer mid-infrared (MIR) data, we use it to build a 3-732 days optical to MIR bolometric lightcurve. To model the <400 days bolometric lightcurve we use a hydrodynamical model grid and a bolometric correction determined with steady-state NLTE modelling. We obtain similar results using the <100 days and <400 days bolometric lightcurves, and using the latter we find a helium core mass of 3.1 (+0.7-0.4) solar masses for SN 2011dh. We present 100-500 days bolometric and photometric lightcurves for the Jerkstrand et al. (2014) steady-state NLTE models, and the preferred 12 solar masses (initial mass) model shows a good overall agreement with the observed lightcurves. We find an excess in the K and the MIR bands developing between 100 and 250 days, during which an increase in the optical decline rat...
The Continuing Story of SN IIb 2013df: New Optical and IR Observations and Analysis
Szalai, Tamás; Nagy, Andrea P; Silverman, Jeffrey M; Wheeler, J Craig; Dhungana, Govinda; Marion, G Howie; Kehoe, Robert; Fox, Ori D; Sárneczky, Krisztián; Marschalkó, Gábor; Bíró, Barna I; Borkovits, Tamás; Hegedüs, Tibor; Szakáts, Róbert; Ferrante, Farley V; Bányai, Evelin; Hodosán, Gabriella; Kelemen, János; Pál, András
2016-01-01
SN 2013df is a nearby Type IIb supernova that seems to be the spectroscopic twin of the well-known SN 1993J. Previous studies revealed many, but not all interesting properties of this event. Our goal was to add new understanding of both the early and late-time phases of SN 2013df. Our spectral analysis is based on 6 optical spectra obtained with the 9.2m Hobby-Eberly Telescope during the first month after explosion, complemented by a near-infrared spectrum. We applied the SYNAPPS spectral synthesis code to constrain the chemical composition and physical properties of the ejecta. A principal result is the identification of "high-velocity" He I lines in the early spectra of SN 2013df, manifest as the blue component of the double-troughed profile at ~5650 A. This finding, together with the lack of clear separation of H and He lines in velocity space, indicates that both H and He features form at the outer envelope during the early phases. We also obtained ground-based BVRI and g'r'i'z' photometric data up to +45...
Power-law expansion of the Universe from the bosonic Lorentzian type IIB matrix model
Ito, Yuta; Nishimura, Jun; Tsuchiya, Asato
2015-11-01
Recent studies on the Lorentzian version of the type IIB matrix model show that (3+1)D expanding universe emerges dynamically from (9+1)D space-time predicted by superstring theory. Here we study a bosonic matrix model obtained by omitting the fermionic matrices. With the adopted simplification and the usage of a large-scale parallel computer, we are able to perform Monte Carlo calculations with matrix size up to N = 512, which is twenty times larger than that used previously for the studies of the original model. When the matrix size is larger than some critical value N c ≃ 110, we find that (3+1)D expanding universe emerges dynamically with a clear large- N scaling property. Furthermore, the observed increase of the spatial extent with time t at sufficiently late times is consistent with a power-law behavior t 1/2, which is reminiscent of the expanding behavior of the Friedmann-Robertson-Walker universe in the radiation dominated era. We discuss possible implications of this result on the original supersymmetric model including fermionic matrices.
SN2003bg: a broad-lined Type IIb Supernova with Hydrogen
Mazzali, Paolo A; Hamuy, Mario; Nomoto, Ken'ichi
2009-01-01
Models for the spectra and the light curve, in the photospheric as well as in the late nebular phase, are used to infer the properties of the very radio-bright, broad-lined type IIb Supernova 2003bg. Consistent fits to the light curve and the spectral evolution are obtained with an explosion that ejected ~ 4 M_sun of material with a kinetic energy of ~ 5 10^51 erg. A thin layer of hydrogen, comprising ~ 0.05 M_sun, is inferred to be present in the ejecta at the highest velocities (v >~ 9000 km/s), while a thicker helium layer, comprising ~ 1.25 M_sun, was ejected at velocities between 6500 and 9000 km/s. At lower velocities, heavier elements are present, including ~ 0.2 M_sun of 56Ni that shape the light curve and the late-time nebular spectra. These values suggest that the progenitor star had a mass of ~ 20-25 M_sun (comparable to, but maybe somewhat smaller than that of the progenitor of the XRF/SN 2008D). The rather broad-lined early spectra are the result of the presence of a small amount of material (~ 0...
The Spectra of Type IIB Flux Compactifications at Large Complex Structure
Brodie, Callum
2015-01-01
We compute the spectra of the Hessian matrix, ${\\cal H}$, and the matrix ${\\cal M}$ that governs the critical point equation of the low-energy effective supergravity, as a function of the complex structure and axio-dilaton moduli space in type IIB flux compactifications at large complex structure. We find both spectra analytically in an $h^{1,2}_-+3$ real-dimensional subspace of the moduli space, and show that they exhibit a universal structure with highly degenerate eigenvalues, independently of the choice of flux, the details of the compactification geometry, and the number of complex structure moduli. In this subspace, the spectrum of the Hessian matrix contains no tachyons, but there are also no critical points. We show numerically that the spectra of ${\\cal H}$ and ${\\cal M}$ remain highly peaked over a large fraction of the sampled moduli space of explicit Calabi-Yau compactifications with 2 to 5 complex structure moduli. In these models, the scale of the supersymmetric contribution to the scalar masses...
A Binary Progenitor for the Type IIb Supernova 2011dh in M51
Benvenuto, Omar G; Nomoto, Ken'ichi
2012-01-01
We perform binary stellar evolutionary calculations following the simultaneous evolution of both stars in the system to study a potential progenitor system for the Type IIb supernova 2011dh. Pre-explosion photometry as well as light-curve modeling have provided constraints on the physical properties of the progenitor system. Here we present a close binary system that is compatible with such constraints. The system is formed by stars of solar composition with 16 Msun + 10 Msun on a circular orbit with an initial period of 125 days. The primary star ends its evolution as a yellow supergiant with a mass of \\sim 4 Msun, a final hydrogen content of \\sim 3-5E-03 Msun and with an effective temperature and luminosity in agreement with the HST pre-explosion observations of SN 2011dh. These results are nearly insensitive to the adopted accretion efficiency factor beta. At the time of explosion, the companion star has an effective temperature of 22 to 40 thousand Kelvin, depending on the value of beta, and lies near the...
An effect of glycoprotein IIb/IIIa inhibitors on the kinetics of red blood cells aggregation.
Sokolova, Irina A; Muravyov, Alexei V; Khokhlova, Maria D; Rikova, Sofya Yu; Lyubin, Evgeny V; Gafarova, Marina A; Skryabina, Maria N; Fedyanin, Angrey A; Kryukova, Darya V; Shahnazarov, Alexander A
2014-01-01
The reversible aggregation of red blood cells (RBCs) continues to be of the basic science and clinical interest. Recently it has been reported about a specific binding between fibrinogen and unknown erythrocyte glycoprotein receptors. The aim of this study was to investigate whether the red blood cell aggregation (RBCA) include the cell-cell interaction using the membrane receptors that bind such ligands as fibrinogen or fibronectin. To test this hypothesis the RBCs were incubated with monafram - the drug of the monoclonal antibodies against glycoprotein (GP) IIb/IIIa, with the GPIIb-IIIa receptor antagonist tirofiban, epifibatide and with the fibrinogen inhibiting peptide. It has been found that the RBC incubation with monafram resulted in a marked RBCA decrease mainly in persons with high level of aggregation. Another research session has shown that RBC incubation with fibronectin was accompanied by a significant RBCA rise. The monafram addition to red cell incubation medium resulted in a significant RBCA lowering. The cell incubation with tirofiban and epifibatide issued in RBCA decrease. The similar results were obtained when RBCs were incubated with the fibrinogen inhibiting peptide. Although monafram, tirofiban, eptifibatide and the fibrinogen inhibiting peptide were related to fibrinogen function they didn't inhibit RBCA completely. Therefore, under moderate and low red blood cell aggregation the cell binding is probably related to nonspecific mode. It seems evident that the specific and nonspecific modes of red blood cell aggregate formation could co-exist. Additional theoretical and experimental investigations in this area are needed.
Temporal variation at the MHC class IIb in wild populations of the guppy (Poecilia reticulata).
Fraser, Bonnie A; Ramnarine, Indar W; Neff, Bryan D
2010-07-01
Understanding genetic diversity in natural populations is a fundamental objective of evolutionary biology. The immune genes of the major histocompatibility complex (MHC) are excellent candidates to study such diversity because they are highly polymorphic in populations. Although balancing selection may be responsible for maintaining diversity at these functionally important loci, temporal variation in selection pressure has rarely been examined. We examine temporal variation in MHC class IIB diversity in nine guppy (Poecilia reticulata) populations over two years. We found that five of the populations changed significantly more at the MHC than at neutral (microsatellite) loci as measured by F(ST), which suggests that the change at the MHC was due to selection and not neutral processes. Additionally, pairwise population differentiation measures at the MHC were higher in 2007 than in 2006, with the signature of selection changing from homogenizing to diversifying selection or neutral evolution. Interestingly, within the populations the magnitude of the change at the MHC between years was related to the change in the proportion of individuals infected by a common parasite, indicating a link between genetic structure and the parasite. Our data thereby implicate temporal variation in selective pressure as an important mechanism maintaining diversity at the MHC in wild populations.
Institute of Scientific and Technical Information of China (English)
Yunfa Yang; Hong Du; Pin Huang; Jianwei Wang; Guangming Zhang; Zhonghe Xu
2008-01-01
Objective:To evaluate X-linked inhibitor of apoptosis protein (XIAP) expression in biopsy specimens from the patients with stage IIB osteosarcomas before chemotherapy to study XIAP expression and its predictive significance of prognosis in stage IIB osteosarcomas.Methods:The expression of XIAP was retrospectively detected by SP immunohistochemistry in 31 cases biopsy specimens from stage IIB osteosarcomas before chemotherapy,and the relationship between XIAP expression and clinicopathologic features of the patients with stage IIB osteosarcomas was analyzed.Results:The osteosarcoma specimens showed strong cell nucleus immunoreaction of XIAP while normal bone specimens showed weak.High XIAP positive expression independently predicted the patient's poor outcome and had no relationship with clinicopathologic variables such as age,gender,location,tumor size,rate of tumor necrosis to preoperative chemotherapy,local recurrence (P＞0.05).Significant correlations were found between high XIAP expression and metastasis (P=0.022),and also between high XIAP expression and final survival (P=0.011).Conclusion:XIAP plays an important role in the development of stage IIB osteosarcomas and XIAP expression of biopsy specimens before chemotherapy can be seen as a promising prognostic marker in early predicting the outcome of patlenta suffering from stage IIB osteosarcomas.
Zeng, Lin; Jin, Shouguang
2003-12-01
Pseudomonas aeruginosa harbors a chromosomal aminoglycoside phosphotransferase gene, aph(3')-IIb, which confers P. aeruginosa resistance to several important aminoglycoside antibiotics, including kanamycin A and B, neomycin B and C, butirosin, and seldomycin F5. The aph(3')-IIb gene has been found to be regulated by an AraC-type transcriptional regulator (HpaA) encoded by a gene located upstream of the aph(3')-IIb gene. In the presence of 4-hydroxyphenylacetic acid (4-HPA), HpaA activates the expression of aph(3')-IIb as well as that of the hpa regulon which encodes metabolic enzymes for the utilization of 4-HPA. hpaA and aph(3')-IIb form an operon, and in response to the presence of 4-HPA, the wild-type P. aeruginosa strain PAK (but not its hpaA mutant strain) displays increased resistance to neomycin. A survey of 39 clinical and 19 environmental isolates of P. aeruginosa demonstrated in all of them the presence of an hpaA-aph gene cluster, while 56 out of the 58 isolates are able to utilize the 4-HPA as a sole carbon source, suggesting a feature common to P. aeruginosa strains. Interestingly, a larger portion of clinical isolates than environmental isolates showed 4-HPA-induced resistance to neomycin. The aph(3')-IIb gene product is likely to function as a metabolic enzyme which has a cross-reactivity with aminoglycosides. These findings provide new insight into the possible mechanism of P. aeruginosa antibiotic resistance.
Feininger, Tomas; Barrero L., Dario; Castro, Nestor; Hall, R.B.
1973-01-01
The Inventario Minero National (IMN), a four-year cooperative geologic mapping and mineral resources appraisal project, was accomplished under an agreement between the Republic of Colombia and the U. S. Agency for International Development from 1964 through 1969. Subzone IIB, consisting essentially of the east half of Zone comprises nearly 20,000 km2 principally in the Department of Antioquia but including also small parts of the Departments of Caldas and Tolima. The rocks in IIB range from Precambrian to Holocene. Precambrian feldspar-quartz gneiss occupies a mosaic of fault-bounded blocks intruded by igneous rocks between the Oto fault and the Rio Magdalena. Paleozoic rocks are extensive, and include lightly metamorphosed graptolite-bearing Ordovician shale at Cristalina, and a major suite of graphitic quartz-mica schist, feldspathic and aluminous gneiss, quartzite, marble, amphibolite, and other rocks. Syntectonic intrusive gneiss included many of the older rocks during a late Paleozoic(?) orogeny, which was accompanied by Abukuma-type metamorphosing from lowermost greenschist to upper amphibolite facies. A Jurassic diorite pluton bounded by faults cuts volcanic rocks of unknown age east of the Otu fault. Cretaceous rocks are major units. Middle Cretaceous carbonaceous shale, sandstone, graywacke, conglomerate, and volcanic rocks are locally prominent. The Antioquian batholith (quartz diorite) of Late Cretaceous age cuts the middle Cretaceous and older rocks. A belt of Tertiary nonmarine clastic sedimentary rocks crops out along the Magdalena Valley. Patches of Tertiary alluvium are locally preserved in the mountains. Quaternary alluvium, much of it auriferous, is widespread in modern stream valleys. Structurally IIB constitutes part of a vast complex synclinorium intruded concordantly by syntectonic catazonal or mesozonal felsic plutons, and by the later epizonal post-tectonic Antioquian batholith. Previously unrecognized major wrench faults are outstanding
T-Duality and Topological Insulators
Mathai, Varghese
2015-01-01
It is well known that topological insulators are classified by a family of groups, which coincidentally also classifies D-brane charges on orientifolds in string theory. In this letter, we extend this correlation via a geometric analog of the real Fourier transform to obtain a novel duality of topological insulators that can be viewed as a condensed matter analog of T-duality in string theory.
Structural basis for quinine-dependent antibody binding to platelet integrin αIIbβ3.
Zhu, Jianghai; Zhu, Jieqing; Bougie, Daniel W; Aster, Richard H; Springer, Timothy A
2015-10-29
Drug-induced immune thrombocytopenia (DITP) is caused by antibodies that react with specific platelet-membrane glycoproteins when the provoking drug is present. More than 100 drugs have been implicated as triggers for this condition, quinine being one of the most common. The cause of DITP in most cases appears to be a drug-induced antibody that binds to a platelet membrane glycoprotein only when the drug is present. How a soluble drug promotes binding of an otherwise nonreactive immunoglobulin to its target, leading to platelet destruction, is uncertain, in part because of the difficulties of working with polyclonal human antibodies usually available only in small quantities. Recently, quinine-dependent murine monoclonal antibodies were developed that recognize a defined epitope on the β-propeller domain of the platelet integrin αIIb subunit (GPIIb) only when the drug is present and closely mimic the behavior of antibodies found in human patients with quinine-induced thrombocytopenia in vitro and in vivo. Here, we demonstrate specific, high-affinity binding of quinine to the complementarity-determining regions (CDRs) of these antibodies and define in crystal structures the changes induced in the CDR by this interaction. Because no detectable binding of quinine to the target integrin could be demonstrated in previous studies, the findings indicate that a hybrid paratope consisting of quinine and reconfigured antibody CDR plays a critical role in recognition of its target epitope by an antibody and suggest that, in this type of drug-induced immunologic injury, the primary reaction involves binding of the drug to antibody CDRs, causing it to acquire specificity for a site on a platelet integrin.
Mechanism of quinine-dependent monoclonal antibody binding to platelet glycoprotein IIb/IIIa.
Bougie, Daniel W; Peterson, Julie; Rasmussen, Mark; Aster, Richard H
2015-10-29
Drug-dependent antibodies (DDAbs) that cause acute thrombocytopenia upon drug exposure are nonreactive in the absence of the drug but bind tightly to a platelet membrane glycoprotein, usually α(IIb)/β3 integrin (GPIIb/IIIa) when the drug is present. How a drug promotes binding of antibody to its target is unknown and is difficult to study with human DDAbs, which are poly-specific and in limited supply. We addressed this question using quinine-dependent murine monoclonal antibodies (mAbs), which, in vitro and in vivo, closely mimic antibodies that cause thrombocytopenia in patients sensitive to quinine. Using surface plasmon resonance (SPR) analysis, we found that quinine binds with very high affinity (K(D) ≈ 10⁻⁹ mol/L) to these mAbs at a molar ratio of ≈ 2:1 but does not bind detectably to an irrelevant mAb. Also using SPR analysis, GPIIb/IIIa was found to bind monovalently to immobilized mAb with low affinity in the absence of quinine and with fivefold greater affinity (K(D) ≈ 2.2 × 10⁻⁶) when quinine was present. Measurements of quinine-dependent binding of intact mAb and fragment antigen-binding (Fab) fragments to platelets showed that affinity is increased 10 000- to 100 000-fold by bivalent interaction between antibody and its target. Together, the findings indicate that the first step in drug-dependent binding of a DDAb is the interaction of the drug with antibody, rather than with antigen, as has been widely thought, where it induces structural changes that enhance the affinity/specificity of antibody for its target epitope. Bivalent binding may be essential for a DDAb to cause thrombocytopenia.
Directory of Open Access Journals (Sweden)
Jennifer L Hodges
Full Text Available Dendritic spines in hippocampal neurons mature from a filopodia-like precursor into a mushroom-shape with an enlarged post-synaptic density (PSD and serve as the primary post-synaptic location of the excitatory neurotransmission that underlies learning and memory. Using myosin II regulatory mutants, inhibitors, and knockdowns, we show that non-muscle myosin IIB (MIIB activity determines where spines form and whether they persist as filopodia-like spine precursors or mature into a mushroom-shape. MIIB also determines PSD size, morphology, and placement in the spine. Local inactivation of MIIB leads to the formation of filopodia-like spine protrusions from the dendritic shaft. However, di-phosphorylation of the regulatory light chain on residues Thr18 and Ser19 by Rho kinase is required for spine maturation. Inhibition of MIIB activity or a mono-phosphomimetic mutant of RLC similarly prevented maturation even in the presence of NMDA receptor activation. Expression of an actin cross-linking, non-contractile mutant, MIIB R709C, showed that maturation into a mushroom-shape requires contractile activity. Loss of MIIB also leads to an elongated PSD morphology that is no longer restricted to the spine tip; whereas increased MIIB activity, specifically through RLC-T18, S19 di-phosphorylation, increases PSD area. These observations support a model whereby myosin II inactivation forms filopodia-like protrusions that only mature once NMDA receptor activation increases RLC di-phosphorylation to stimulate MIIB contractility, resulting in mushroom-shaped spines with an enlarged PSD.
Role of Various Extractants in Removing Group-IIB Elements of Soils Incubated with EDTA
Directory of Open Access Journals (Sweden)
Tanmoy Karak
2004-01-01
Full Text Available This paper presents the results of an experimental investigation undertaken to evaluate different extractant solutions viz. HCl, Mg(NO32, and DTPA with the range of concentration from 0.001 to 0.1N after incubation with group-IIB metals (Zn, Cd, and Hg and EDTA to understand the capability to remove Zn, Cd, and Hg from soils. Two noncontaminated soils, one acidic (GHL and the other alkaline (KAP, in reaction were taken from an agricultural field of West Bengal, India for this investigation. Experiments were conducted on these two soils spiked with ZnII, CdII, and HgII in concentrations of 612, 321, and 215 mg/kg for soil GHL and 778, 298, and 157 mg/kg for soil KAP, respectively, which simulate typical electroplating waste contamination. The removal of Zn, Cd, and Hg in soil GHL within the range of HCl concentrations was 8.216.5, 12.219.1, and 4.36.9 whereas these were 6.57.6, 8.514.1, and 3.25.2 in soil KAP. The removal of Zn, Cd, and Hg in soil GHL within the range of Mg(NO32 concentrations were 12.228.5, 19.124.6, and 18.219.1 whereas these were 9.112.1, 8.312.1, and 10.648.1 in soil KAP. For DTPA extractant, the percent removal of metal was found to be significantly higher than the other two extractants, which corroborates that DTPA is a better extractant for soil cleaning.
Glycoprotein IIb/IIIa and P2Y12 Induction by Oligochitosan Accelerates Platelet Aggregation
Halim, Ahmad Sukari; Hussein, Abdul Rahim; Ujang, Zanariah
2014-01-01
Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y12, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y12 is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC) with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C), and oligochitosan 53 (O-C 53)]. We studied gpiibiiia and P2Y12 through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%), followed by O-C (65.5 ± 7.17%). Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y12 (1.12 ± 0.03-fold) compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y12 levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y12, thus accelerating platelet aggregation in vitro. PMID:25247182
Analysis of Radiotherapy Associated Factors in Stage IIb Carcinoma of Uterine Cervix
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Moon, Chang Woo; Jeung, Tae Sig; Yum, Ha Yong [Kosin Medical College of Medicine, Pusan (Korea, Republic of)
1990-12-15
331 patients of stage IIb uterine cervix cancer treated by radiation alone at Kosin Medical Center between June 1980 and Dec. 1985 were analysed to determine parameters of radiotherapy associated to disease states. Survival rate was highest among the reported (82.8% for crude and 82.4% for disease free survival). Pelvic control rate in 6 weeks after the end of radiotherapy was 93.6% in the patients treated with ICR following total pelvic radiation and 71.6% with small field additional external irradiation. 5 year survival rate in those who achieved pelvic control was 98. 9% and 12.9% in those who had pelvic failure and/or metastasis after radiation. The survival rate figured maximal 88.5% with dosage of 7500-8500 cGy to point A with acceptable incidence of complications (4.9%) but without increasing survival above it and minimal 74.1% with dosage of less than 6500 cGy. The treatment failure was counted 18.7% (62 of 331 patients): Local failure 72. 6% ( 45 of 62 patients), locoregional failure 3.2% (2 of 62 patients) and distant failure 24% (15 of 62 patients). Late complications were found In 50 patients (15.1%) and 42% of them was rectal bleeding and stenosis. The dose of 8500 cGy to point A was found to be critical for complication and 70% of complications occurred above it and was more serious one such as fistula. Rectal complications were developed above rectal dose 6500 cGy and bladder complication above bladder dose 7500 cGy. Major cause of death was cachexia due to locoregional failure (73.7% of death), next was due to metastasis to lung, liver and bone, and only 3 patients died of complication of intestinal perforations and obstruction. In conclusion higher external radiation dose for a bulky uterine cervix and barrel shaped uterus was essential for local control.
Dorkin, Henry L; Staab, Doris; Operschall, Elisabeth; Alder, Jeff; Criollo, Margarita
2015-01-01
Treatment of infective bronchitis involving Pseudomonas aeruginosa is a cornerstone of care in patients with cystic fibrosis (CF). This phase IIb, randomised, double-blind, placebo-controlled study assessed the efficacy and safety of ciprofloxacin dry powder for inhalation (DPI) in this population. Patients with CF, ≥12 years of age (N=286), were randomised to ciprofloxacin DPI (32.5 mg (n=93) or 48.75 mg (n=93)), or corresponding placebo (32.5 mg, n=65; 48.75 mg, n=35) twice daily for 28 days. The primary objective was the change in forced expiratory volume in 1 s (FEV1) from baseline (day 0) to end of treatment (day 29) in the intent-to-treat population for ciprofloxacin DPI compared with the corresponding placebo group. The primary effectiveness objective was not met; there were no significant differences in change in FEV1 between ciprofloxacin DPI and the corresponding placebo group for either dose (p=0.154). However, in pooled analyses, FEV1 decline from baseline to treatment end was significantly lower with ciprofloxacin DPI than with placebo (pooled data; p=0.02). Ciprofloxacin DPI showed positive effects on sputum bacterial load and quality of life, but these effects were not maintained at the 4-week follow-up. Ciprofloxacin DPI was well tolerated and there were no significant differences in type/incidence of treatment-emergent adverse events by treatment group (p=0.115). Further investigations are needed to determine the full scope of the beneficial effects of ciprofloxacin DPI for patients with CF. Clinicaltrials.gov NCT00645788; EudraCT 2008-008314-40.
The Two-Peptide (Class-IIb) Bacteriocins: Genetics, Biosynthesis, Structure, and Mode of Action
Nissen-Meyer, Jon; Oppegård, Camilla; Rogne, Per; Haugen, Helen Sophie; Kristiansen, Per Eugen
The two-peptide (class-IIb) bacteriocins consist of two different peptides, both of which are required to obtain high antimicrobial activity. These bacteriocins kill target-cells by inducing membrane-leakage and they seem to display some specificity with respect to the molecules they transfer across membranes. The genes encoding the two peptides of two-peptide bacteriocins are next to each other on the same operon. In the same or a nearby operon are genes encoding (i) the immunity protein that protects the bacteriocin-producer from its own bacteriocin, (ii) a dedicated ABC-transporter that exports the bacteriocin from cells and cleaves off the N-terminal bacteriocin leader sequence, and (iii) an accessory protein whose exact function has not been fully clarified. Some two-peptide bacteriocins appear to be produced constitutively, whereas the production of other two-peptide bacteriocins is regulated through a three-component regulatory system that consists of a peptide pheromone, a membrane-associated histidine protein kinase, and response regulators. It has recently been proposed that the two peptides of (some) two-peptide bacteriocins may form a membrane-penetrating helix-helix structure involving helix-helix interacting GxxxG-motifs present in all currently characterized two-peptide bacteriocins. It has also been suggested that the helix-helix structure interacts with an integrated membrane (transport) protein, thus inducing a conformational change in the protein, which in turn causes membrane-leakage. This proposed mode-of-action is similar to that of the pediocin-like (class-IIa) bacteriocins and lactococcin A, which bind to a part of the mannose phosphotransferase permease that is embedded in the cell membrane, thereby altering the conformation of the permease in a manner that causes membrane-leakage and cell death.
Matheis, Erika A; Spratley, E Meade; Hayes, Curtis W; Adelaar, Robert S; Wayne, Jennifer S
2014-01-01
Adult acquired flatfoot deformity is a degenerative disease causing medial arch dysfunction. Surgical correction has typically involved tendon reconstruction with calcaneal osteotomy; however, the postoperative changes have not been fully characterized. The present study assessed the success of surgical correction of Stage IIb adult acquired flatfoot deformity through changes in plantar pressures and patient-generated outcome scores. With Institutional Review Board approval, 6 participants were evaluated before and after surgery using pedobarography, the Foot and Ankle Outcome Score, and the Medical Outcomes Study 36-item short-form questionnaire. The plantar pressures were recorded using a TekScan HRMat(®) during walking and in a 1- and 2-foot stance. The resulting contour maps were segmented into 9 regions, with the peak pressure, normalized force, and arch index calculated. Surgical effects were analyzed using paired t tests. Postoperatively, the Foot and Ankle Outcome Score and Medical Outcomes Study 36-item short-form questionnaire scores increased significantly from 180 ± 78 to 360 ± 136 (p < .03) and 47 ± 18 to 71 ± 19 (p = .06), respectively. During the 2-foot stance, the normalized force had increased significantly in the lateral midfoot (p < .03), although no significant differences were found in peak pressures. No significant differences were observed in the 1-foot stance. During walking, the normalized force increased significantly in the lateral mid- and forefoot (p < .05). The peak pressure increased significantly in the lateral forefoot (p < .01). The arch index values demonstrated no significant changes. The increased questionnaire scores indicated that surgical correction improved the self-perceived health of the participants. Lateral shifts in the peak pressure and normalized force suggest that forefoot and midfoot loading is altered postoperatively, consistent with the goal of offloading the dysfunctional arch. Thus, the present study has
Lawlor, Michael W; Read, Benjamin P; Edelstein, Rachel; Yang, Nicole; Pierson, Christopher R; Stein, Matthew J; Wermer-Colan, Ariana; Buj-Bello, Anna; Lachey, Jennifer L; Seehra, Jasbir S; Beggs, Alan H
2011-02-01
X-linked myotubular myopathy (XLMTM) is a congenital disorder caused by deficiency of the lipid phosphatase, myotubularin. Patients with XLMTM often have severe perinatal weakness that requires mechanical ventilation to prevent death from respiratory failure. Muscle biopsy specimens from patients with XLMTM exhibit small myofibers with central nuclei and central aggregations of organelles in many cells. It was postulated that therapeutically increasing muscle fiber size would cause symptomatic improvement in myotubularin deficiency. Recent studies have elucidated an important role for the activin-receptor type IIB (ActRIIB) in regulation of muscle growth and have demonstrated that ActRIIB inhibition results in significant muscle hypertrophy. To evaluate whether promoting muscle hypertrophy can attenuate symptoms resulting from myotubularin deficiency, the effect of ActRIIB-mFC treatment was determined in myotubularin-deficient (Mtm1δ4) mice. Compared with wild-type mice, untreated Mtm1δ4 mice have decreased body weight, skeletal muscle hypotrophy, and reduced survival. Treatment of Mtm1δ4 mice with ActRIIB-mFC produced a 17% extension of lifespan, with transient increases in weight, forelimb grip strength, and myofiber size. Pathologic analysis of Mtm1δ4 mice during treatment revealed that ActRIIB-mFC produced marked hypertrophy restricted to type 2b myofibers, which suggests that oxidative fibers in Mtm1δ4 animals are incapable of a hypertrophic response in this setting. These results support ActRIIB-mFC as an effective treatment for the weakness observed in myotubularin deficiency. Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
Ina, Koichiro; Hayashi, Toshio; Araki, Atsushi; Kawashima, Seinosuke; Sone, Hirohito; Watanabe, Hiroshi; Ohrui, Takashi; Yokote, Koutaro; Takemoto, Minoru; Kubota, Kiyoshi; Noda, Mitsuhiko; Noto, Hiroshi; Ding, Qun-Fang; Zhang, Jie; Yu, Ze-Yun; Yoon, Byung-Koo; Nomura, Hideki; Kuzuya, Masafumi
2014-10-01
The risk factors for ischemic heart disease (IHD) or cerebrovascular accident (CVA) in elderly diabetic individuals with type IIb dyslipidemia are not fully known. Therefore, we investigated the relationship between lipid levels and IHD and CVA in diabetic individuals with type IIb dyslipidemia. The Japan Cholesterol and Diabetes Mellitus Study is a prospective cohort study of 4014 type 2 diabetic patients (1936 women; age 67.4 ± 9.5 years). The primary end-points were the onset of IHD or CVA. Lipid and glucose levels, and other factors were investigated in relation to the occurrence of IHD or CVA. A total of 462 participants were included in the group of patients with type IIb dyslipidemia. The 462 diabetic participants with type IIb dyslipidemia were divided into those who were aged 75 years (n=168, 190 and 104, respectively). High-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol/HDL-C were significantly associated with the risk of cardiovascular events in diabetic individuals with type IIb dyslipidemia who were aged HDL-C and diastolic blood pressure was significantly associated with cardiovascular events in patients aged 65-74 years. Non-HDL-C was not significantly associated with the risk of cardiovascular events. Multiple regression analysis showed that lower HDL-C was significantly associated with the risk of cardiovascular events in diabetic individuals with type IIb dyslipidemia who were aged HDL-C was an important risk factor for cardiovascular events in diabetic individuals with type IIb dyslipidemia who were aged <75 years. © 2013 Japan Geriatrics Society.
De Luca, Giuseppe; Michael Gibson, C; Bellandi, Francesco; Murphy, Sabina; Maioli, Mauro; Noc, Marko; Zeymer, Uwe; Dudek, Dariusz; Arntz, Hans-Richard; Zorman, Simona; Gabriel, H Mesquita; Emre, Ayse; Cutlip, Donald; Rakowski, Tomasz; Gyongyosi, Mariann; Huber, Kurt; Van't Hof, Arnoud W J
2009-10-01
The Early Glycoprotein IIb-IIIa inhibitors in Primary angioplasty (EGYPT) cooperation aimed at evaluating, by pooling individual patient's data of randomized trials, the benefits of pharmacological facilitation with Gp IIb-IIIa inhibitors among STEMI patients undergoing primary angioplasty. In the current study we analyze the benefits of early Gp IIb-IIIa inhibitors in diabetic patients. The literature was scanned by formal searches of electronic databases (MEDLINE, EMBASE) from January 1990 to October 2007. We examined all randomized trials on facilitation by early administration of Gp IIb-IIIa inhibitors in STEMI. No language restrictions were enforced. Individual patients' data were obtained from 11 out of 13 trials, including 1,662 patients. Diabetes was present in 281 (16.9%). Early Gp IIb-IIIa inhibitors were associated with improved preprocedural TIMI 3 flow (26.0% vs. 13.1%, P = 0.006), postprocedural TIMI 3 flow (90.1% vs. 75.0%, P = 0.18), MBG 3 (40.8% vs. 30.4%, P = 0.004), and less distal embolization (11.6% vs. 20.8%, P = 0.05). However, early Gp IIb-IIIa inhibitors did not significantly reduce mortality (8.3% vs. 9.5%, P = 0.64). This meta-analysis shows that pharmacological facilitation with early administration of Gp IIb-IIIa inhibitors in STEMI patients with diabetes undergoing primary angioplasty, is associated with significant benefits in terms of preprocedural and postprocedural TIMI flow, improved myocardial perfusion, without significant benefits in mortality.
Directory of Open Access Journals (Sweden)
Mushtaq Mir
2013-01-01
Full Text Available Background: The management of locally advanced (Stage IIb and III breast cancer is challenging. It often includes multimodal treatment with systemic therapy and/or radiation therapy and surgery. Immediate breast reconstruction has not traditionally been performed in these patients. We review the results of immediate rectus abdominis musculo-cutaneous (TRAM/VRAM flap in 60 patients treated for Stage IIb and III breast cancer. Materials and Methods: Data were collected prospectively on 60 patients diagnosed with Stage IIb (32 patients and Stage III (28 patients breast cancer between May 2008 and May 2012. All patients had mastectomy and immediate rectus abdominis myocutaneous reconstruction (TRAM in 40 patients and VRAM in 20 patients. All patients received primary systemic therapy, and all patients received postoperative radiotherapy to the operative site. Results: Mean age was 40.13 (range 28-53 years, mean hospital stay was 8.86 days and mean follow-up for the group was 28 months. Neither of them developed local disease recurrence in the operative site till the last follow-up. Eight (13.3% patients had some delay in chemo-radiation therapy due to flap-related complications. Flap-related complications were present in eight patients (partial flap failure in four and superficial skin necrosis in four. There was no adverse effect of chemo-radiation therapy on reconstructed breast. Conclusion: Immediate TRAM/VRAM breast reconstruction for locally advanced breast cancer is not associated with a significant delay in adjuvant therapy or an increased risk of local relapse. Radiation therapy can be delivered to the reconstructed breast when indicated without difficulty. Breast reconstruction facilitates surgical resection of locally advanced breast cancer with primary closure and should be considered if the patient desires immediate breast reconstruction.
Okazawa-Sakai, Mika; Mabuchi, Seiji; Isohashi, Fumiaki; Kawashima, Atsushi; Yokoi, Eriko; Ogawa, Kazuhiko; Kimura, Tadashi
2017-08-17
To investigate the predictors of distant relapse in International Federation of Gynecology and Obstetrics (FIGO) stage IIB-IVA cervical cancer patients treated with definitive radiotherapy (RT). The clinical data of 219 patients with FIGO stage IIB-IVA cervical cancer treated with definitive RT between January 1997 and December 2011 were retrospectively reviewed. The cumulative distant relapse, progression-free survival (PFS) and overall survival (OS) rates were calculated using the Kaplan-Meier method and compared using the log-rank test. A Cox proportional hazards regression model was used to investigate the predictors of distant relapse in patients. Following treatment with definitive RT, 61 of the 219 (27.9%) patients developed distant relapse with median PFS and OS rates of 9.9 and 32.8 months, and estimated five-year PFS and OS rates of 4.9% and 21.3%, respectively. Multivariate analysis revealed that pelvic node metastasis, pretreatment leukocytosis and pretreatment neutrophilia were significant predictors of distant relapse. The risk of developing distant relapse was found to be associated with the number of predictors that the patients displayed: the estimated five-year distant relapse rates of the patients with no predictors, one predictor and two predictors were 20.3%, 35.5% and 88.9%, respectively. Roughly 28% of patients with FIGO stage IIB-IVA cervical cancer developed distant relapse after definitive RT. Pelvic lymph node metastasis and pretreatment leukocytosis/neutrophilia are independent predictors of distant relapse. © 2017 Japan Society of Obstetrics and Gynecology.
Balvers, W G; Boersma, M G; Veeger, C; Rietjens, I M
1992-09-15
The cytochrome P-450-dependent O-dealkylation of alkoxyresorufins was used to study the effect of cumene hydroperoxide on cytochrome P-450 IIB1 and IA1 in microsomal and reconstituted systems. In liver microsomal systems from respectively phenobarbital and 3-methylcholanthrene pretreated male Wistar rats, cytochrome P-450 IIB1-dependent pentoxyresorufin-O-dealkylation appeared to be more sensitive to cumene hydroperoxide treatment than cytochrome P-450 IA1-dependent ethoxyresorufin-O-dealkylation. This phenomenon was also observed when the cumene hydroperoxide sensitivity of P-450 IIB1 and IA1 was studied in an isosafrole pretreated rat liver microsomal system. The decrease in alkoxy-O-dealkylating activities appeared to proceed by destruction of the cytochrome P-450 component of the enzyme system. Purification and reconstitution of the enzyme system components in a system in which the isolated proteins were not incorporated into a membrane resulted in the disappearance of the difference in sensitivity between the two P-450 enzymes. However, in a reconstituted system with membrane incorporated proteins, again cytochrome P-450 IIB1 expressed a higher sensitivity towards cumene hydroperoxide than cytochrome P-450 IA1. From this it was concluded that the differential cumene hydroperoxide sensitivity of cytochrome P-450 IIB1 and IA1 is not caused by an intrinsic difference in their sensitivity but by a differential effect of membrane incorporation on their cumene hydroperoxide sensitivity.
(2,2) and (0,4) Supersymmetric Boundary Conditions in 3d N = 4 Theories and Type IIB Branes
Chung, Hee-Joong
2016-01-01
The half-BPS boundary conditions preserving N = (2,2) and N = (0,4) supersymmetry in 3d N = 4 supersymmetric gauge theories are examined. The BPS equations admit decomposition of the bulk supermultiplets into specific boundary supermultiplets of preserved supersymmetry. Bogomolony-like equations and Nahm-like equations arise in the vector multiplet BPS boundary conditions and Robin-type boundary conditions appear for the hypermultiplet coupled to vector multiplet. The half-BPS boundary conditions are realized in the brane configurations of Type IIB string theory.
Directory of Open Access Journals (Sweden)
Oliveira Helena CF
2005-06-01
Full Text Available Abstract Background Human immunodeficiency virus (HIV infection is very prevalent in Brazil. HIV therapy has been recently associated with coronary heart disease (CHD. Dyslipidemia is a major risk factor for CHD that is frequently described in HIV positive patients, but very few studies have been conducted in Brazilian patients evaluating their lipid profiles. Methods In the present work, we evaluated the frequency and severity of dyslipidemia in 257 Brazilian HIV positive patients. Two hundred and thirty-eight (93% were submitted to antiretroviral therapy (224 treated with protease inhibitors plus nucleoside reverse transcriptase inhibitors, 14 treated only with the latter, 12 naive and 7 had no records of treatment. The average time on drug treatment with antiretroviral therapy was 20 months. None of the patients was under lipid lowering drugs. Cholesterol, triglyceride, phospholipid and free fatty acids were determined by enzymatic colorimetric methods. Lipoprotein profile was estimated by the Friedewald formula and Fredrickson's phenotyping was obtained by serum electrophoresis on agarose. Apolipoprotein B and AI and lipoprotein "a" were measured by nephelometry. Results The Fredrickson phenotypes were: type IIb (51%, IV (41%, IIa (7%. In addition one patient was type III and another type V. Thirty-three percent of all HIV+ patients presented serum cholesterol levels ≥ 200 mg/dL, 61% LDL-cholesterol ≥ 100 mg/dL, 65% HDL-cholesterol below 40 mg/dL, 46% triglycerides ≥ 150 mg/dL and 10% have all these parameters above the limits. Eighty-six percent of patients had cholesterol/HDL-cholesterol ratio ≥ 3.5, 22% increased lipoprotein "a", 79% increased free fatty acids and 9% increased phospholipids. The treatment with protease inhibitors plus nucleoside reverse transcriptase inhibitors increased the levels of cholesterol and triglycerides in these patients when compared with naïve patients. The HDL-cholesterol (p = 0.01 and
Zeng, Lin; Jin, Shouguang
2003-01-01
Pseudomonas aeruginosa harbors a chromosomal aminoglycoside phosphotransferase gene, aph(3′)-IIb, which confers P. aeruginosa resistance to several important aminoglycoside antibiotics, including kanamycin A and B, neomycin B and C, butirosin, and seldomycin F5. The aph(3′)-IIb gene has been found to be regulated by an AraC-type transcriptional regulator (HpaA) encoded by a gene located upstream of the aph(3′)-IIb gene. In the presence of 4-hydroxyphenylacetic acid (4-HPA), HpaA activates the expression of aph(3′)-IIb as well as that of the hpa regulon which encodes metabolic enzymes for the utilization of 4-HPA. hpaA and aph(3′)-IIb form an operon, and in response to the presence of 4-HPA, the wild-type P. aeruginosa strain PAK (but not its hpaA mutant strain) displays increased resistance to neomycin. A survey of 39 clinical and 19 environmental isolates of P. aeruginosa demonstrated in all of them the presence of an hpaA-aph gene cluster, while 56 out of the 58 isolates are able to utilize the 4-HPA as a sole carbon source, suggesting a feature common to P. aeruginosa strains. Interestingly, a larger portion of clinical isolates than environmental isolates showed 4-HPA-induced resistance to neomycin. The aph(3′)-IIb gene product is likely to function as a metabolic enzyme which has a cross-reactivity with aminoglycosides. These findings provide new insight into the possible mechanism of P. aeruginosa antibiotic resistance. PMID:14638496
Energy Technology Data Exchange (ETDEWEB)
Springer, Timothy A.; Zhu, Jianghai; Xiao, Tsan (Harvard-Med)
2009-01-12
Hemostasis and thrombosis (blood clotting) involve fibrinogen binding to integrin {alpha}{sub IIb}{beta}{sub 3} on platelets, resulting in platelet aggregation. {alpha}{sub v}{beta}{sub 3} binding fibrinogen via an Arg-Asp-Gly (RGD) motif in fibrinogen's {alpha} subunit. {alpha}{sub IIb}{beta}{sub 3} also binds to fibrinogen; however, it does so via an unstructured RGD-lacking C-terminal region of the {gamma} subunit ({gamma}C peptide). These distinct modes of fibrinogen binding enable {alpha}{sub IIb}{beta}{sub 3} and {alpha}{sub v}{beta}{sub 3} to function cooperatively in hemostasis. In this study, crystal structures reveal the integrin {alpha}{sub IIb}{beta}{sub 3}-{gamma}C peptide interface, and, for comparison, integrin {alpha}{sub IIb}{beta}{sub 3} bound to a lamprey {gamma}C primordial RGD motif. Compared with RGD, the GAKQAGDV motif in {gamma}C adopts a different backbone configuration and binds over a more extended region. The integrin metal ion-dependent adhesion site (MIDAS) Mg{sup 2+} ion binds the {gamma}C Asp side chain. The adjacent to MIDAS (ADMIDAS) Ca{sup 2+} ion binds the {gamma}C C terminus, revealing a contribution for ADMIDAS in ligand binding. Structural data from this natively disordered {gamma}C peptide enhances our understanding of the involvement of {gamma}C peptide and integrin {alpha}{sub IIb}{beta}{sub 3} in hemostasis and thrombosis.
Klimov, A N; Konstantinov, V O; Lipovetsky, B M; Kuznetsov, A S; Lozovsky, V T; Trufanov, V F; Plavinsky, S L; Gundermann, K J; Schumacher, R
1995-12-01
In patients with moderate, dietary noncorrigible hyperlipoproteinemia type IIb and ischemic heart disease, treatment with nicotinic acid is limited by the side effects of the drug. In 100 patients, 6-month treatment with nicotinic acid (n = 50) or "essential" phospholipids (EPL); Lipostabil, manufacturer: Rhône-Poulenc Rorer) (n = 50) indicated comparable efficacy for both substances: Significant (p < .001) reductions of serum total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride values were similar in both groups, while nicotinic acid increased high-density lipoprotein (HDL) cholesterol significantly (p < .01) better than Lipostabil. A detailed analysis of ultracentrifugal lipoprotein profiles, hydroperoxide concentrations in LDL, and cholesterol-accepting properties of HDL in a small number of Lipostabil- and nicotinic acid-treated patients revealed favorable shifts in the lipoprotein profile, significant (p < .05) reductions of LDL hydroperoxides, and favorable increases of the most antiatherogenic HDL2b subfraction only in the Lipostabil-treated group. Clinically, both medications reduced the intensity and number of angina pectoris attacks per week (p < .05), but only Lipostabil-treated patients significantly (p < .05) increased their working capacity in the veloergometric test. Since in the nicotinic acid-treated group dropouts (nine patients, eight related to the drug) and side effects [14] exceeded those in the Lipostabil-treated group (two dropouts not related to the drug, no side effects), it is suggested that Lipostabil is a preferable alternative in the treatment of patients with moderate, dietary noncorrigible hyperlipoproteinemia IIb and ischemic heart disease.
Supernova 2010as: the lowest-velocity member of a family of flat-velocity type IIb supernovae
Energy Technology Data Exchange (ETDEWEB)
Folatelli, Gastón; Bersten, Melina C.; Nomoto, Ken' ichi [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Kuncarayakti, Hanindyo; Hamuy, Mario [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Olivares Estay, Felipe; Pignata, Giuliano [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile); Anderson, Joseph P. [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago (Chile); Holmbo, Simon; Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Maeda, Keiichi [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Morrell, Nidia; Contreras, Carlos; Phillips, Mark M. [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Förster, Francisco [Center for Mathematical Modelling, Universidad de Chile, Avenida Blanco Encalada 2120 Piso 7, Santiago (Chile); Prieto, José Luis [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544 (United States); Valenti, Stefano [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Afonso, Paulo; Altenmüller, Konrad; Elliott, Jonny, E-mail: gaston.folatelli@ipmu.jp [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, D-85740 Garching (Germany); and others
2014-09-01
We present extensive optical and near-infrared photometric and spectroscopic observations of the stripped-envelope supernova SN 2010as. Spectroscopic peculiarities such as initially weak helium features and low expansion velocities with a nearly flat evolution place this object in the small family of events previously identified as transitional Type Ib/c supernovae (SNe). There is ubiquitous evidence of hydrogen, albeit weak, in this family of SNe, indicating that they are in fact a peculiar kind of Type IIb SNe that we name 'flat-velocity' Type IIb. The flat-velocity evolution—which occurs at different levels between 6000 and 8000 km s{sup –1} for different SNe—suggests the presence of a dense shell in the ejecta. Despite the spectroscopic similarities, these objects show surprisingly diverse luminosities. We discuss the possible physical or geometrical unification picture for such diversity. Using archival Hubble Space Telescope images, we associate SN 2010as with a massive cluster and derive a progenitor age of ≈6 Myr, assuming a single star-formation burst, which is compatible with a Wolf-Rayet progenitor. Our hydrodynamical modeling, on the contrary, indicates that the pre-explosion mass was relatively low, ≈4 M {sub ☉}. The seeming contradiction between a young age and low pre-SN mass may be solved by a massive interacting binary progenitor.
Supernova 2010as: the Lowest-Velocity Member of a Family of Flat-Velocity Type IIb Supernovae
Folatelli, Gastón; Kuncarayakti, Hanindyo; Estay, Felipe Olivares; Anderson, Joseph P; Holmbo, Simon; Maeda, Keiichi; Morrell, Nidia; Nomoto, Ken'ichi; Pignata, Giuliano; Stritzinger, Maximilian; Contreras, Carlos; Förster, Francisco; Hamuy, Mario; Phillips, Mark M; Prieto, José Luis; Valenti, Stefano; Afonso, Paulo; Altenmüller, Konrad; Elliott, Jonny; Greiner, Jochen; Updike, Adria; Haislip, Joshua B; LaCluyze, Aaron P; Moore, Justin P; Reichart, Daniel E
2014-01-01
We present extensive optical and near-infrared photometric and spectroscopic observations of the stripped-envelope (SE) supernova SN 2010as. Spectroscopic peculiarities, such as initially weak helium features and low expansion velocities with a nearly flat evolution, place this object in the small family of events previously identified as transitional Type Ib/c supernovae (SNe). There is ubiquitous evidence of hydrogen, albeit weak, in this family of SNe, indicating that they are in fact a peculiar kind of Type IIb SNe that we name "flat-velocity Type IIb". The flat velocity evolution---which occurs at different levels between 6000 and 8000 km/s for different SNe---suggests the presence of a dense shell in the ejecta. Despite the spectroscopic similarities, these objects show surprisingly diverse luminosities. We discuss the possible physical or geometrical unification picture for such diversity. Using archival HST images we associate SN 2010as with a massive cluster and derive a progenitor age of ~6 Myr, ass...
HCV IRES domain IIb affects the configuration of coding RNA in the 40S subunit's decoding groove.
Filbin, Megan E; Kieft, Jeffrey S
2011-07-01
Hepatitis C virus (HCV) uses a structured internal ribosome entry site (IRES) RNA to recruit the translation machinery to the viral RNA and begin protein synthesis without the ribosomal scanning process required for canonical translation initiation. Different IRES structural domains are used in this process, which begins with direct binding of the 40S ribosomal subunit to the IRES RNA and involves specific manipulation of the translational machinery. We have found that upon initial 40S subunit binding, the stem-loop domain of the IRES that contains the start codon unwinds and adopts a stable configuration within the subunit's decoding groove. This configuration depends on the sequence and structure of a different stem-loop domain (domain IIb) located far from the start codon in sequence, but spatially proximal in the IRES•40S complex. Mutation of domain IIb results in misconfiguration of the HCV RNA in the decoding groove that includes changes in the placement of the AUG start codon, and a substantial decrease in the ability of the IRES to initiate translation. Our results show that two distal regions of the IRES are structurally communicating at the initial step of 40S subunit binding and suggest that this is an important step in driving protein synthesis.
Dessart, Luc; Woosley, Stan; Livne, Eli; Waldman, Roni; Yoon, Sung-Chul; Langer, Norbert
2016-01-01
We present 1-D non-Local-Thermodynamic-Equilibrium time-dependent radiative-transfer simulations for a large grid of supernovae (SNe) IIb/Ib/Ic that result from the terminal explosion of the mass donor in a close-binary system. Our sample covers ejecta masses $M_{\\rm e}$ of 1.7$-$5.2M$_\\odot$, kinetic energies $E_{\\rm kin}$ of 0.6$-$5.0$\\times$10$^{51}$erg, and $^{56}$Ni masses of 0.05$-$0.30M$_\\odot$. We find a strong correlation between the $^{56}$Ni mass and the photometric properties at maximum, and between the rise time to bolometric maximum and the post-maximum decline rate. We confirm the small scatter in ($V-R$) at 10d past $R$-band maximum. The quantity $V_{\\rm m} \\equiv \\sqrt{2E_{\\rm kin}/M_{\\rm e}}$ is comparable to the Doppler velocity measured from HeI 5875\\AA\\ at maximum in SNe IIb/Ib, although some scatter arises from the uncertain level of chemical mixing. The OI7772\\AA\\ line may be used for SNe Ic, but the correspondence deteriorates with higher ejecta mass/energy. We identify a temporal reve...
Oh, Chung-Hun; Shin, Jang-In; Mo, Sang Joon; Yun, Sung-Jo; Kim, Sung-Hoon; Rhee, Yun-Hee
2013-07-01
L-sulforaphane was identified as an anticarcinogen that could produce quinine reductase and a phase II detoxification enzyme. In recent decades, multi-effects of L-sulforaphane may have been investigated, but, to the authors' knowledge, the antiplatelet activation of L-sulforaphane has not been studied yet.In this study, 2 μg/ml of collagen, 50 μg/ml of ADP and 5 μg/ml of thrombin were used for platelet aggregations with or without L-sulforaphane. L-sulforaphane inhibited the platelet aggregation dose-dependently. Among these platelet activators, collagen was most inhibited by L-sulforaphane, which markedly decreased collagen-induced glycoprotein IIb/IIIa activation and thromboxane A2 (TxA2) formation in vitro. L-sulforaphane also reduced the collagen and epinephrine-induced pulmonary embolism, but did not affect prothrombin time (PT) in vivo. This finding demonstrated that L-sulforaphane inhibited the platelet activation through an intrinsic pathway.L-sulforaphane had a beneficial effect on various pathophysiological pathways of the collagen-induced platelet aggregation and thrombus formation as a selective inhibition of cyclooxygenase and glycoprotein IIb/IIIa antagonist. Thus, we recommend L-sulforaphane as a potential antithrombotic drug.
Institute of Scientific and Technical Information of China (English)
Patrcia Vidigal; Clia Guiu-Aragons; Sara Amncio; Lusa Carvalho
2015-01-01
Peroxiredoxins (Prx) catalyse the reduction of hydrogen peroxide (H2O2) and, in association with catalases and other peroxidases, may participate in signal transduction by regulating intercel ular H2O2 concentration that in turn can control gene transcription and cel signaling. Using virus-induced-gene-silencing (VIGS), 2-Cys Peroxiredoxin (2CysPrx) family and type-II Peroxiredoxin B (PrxI B) gene were silenced in Nicotiana benthamiana, to study the impact that the loss of function of each Prx would have in the antioxidant system under control (22 °C) and severe heat stress conditions (48 °C). The results showed that both Prxs, although in different organel es, influence the regeneration of ascorbate to a significant extent, but with different purposes. 2CysPrx affects abscisic acid (ABA) biosynthesis through ascorbate, while PrxIIB does it probably through the xanthophyl cycle. Moreover, 2CysPrx is key in H2O2 scavenging and in consequence in the regulation of ABA signal-ing downstream of reactive oxygen species and PrxIIB provides an important assistance for H2O2 peroxisome scavenges.
Type IIb supernova SN 2011dh: Spectra and photometry from the ultraviolet to the near-infrared
Energy Technology Data Exchange (ETDEWEB)
Marion, G. H.; Kirshner, Robert P.; Foley, Ryan J.; Berlind, Perry; Bieryla, Allyson; Calkins, Michael L.; Challis, Peter; Chornock, Ryan; Esquerdo, Gilbert A.; Falco, Emilio E.; Friedman, Andrew S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Vinko, Jozsef [University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Bloom, Joshua S. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Chevalier, Roger A. [Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States); Culliton, Chris; Curtis, Jason L. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Everett, Mark E. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); France, Kevin [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Fransson, Claes [Department of Astronomy, The Oskar Klein Centre, Stockholm University, S-106 91 Stockholm (Sweden); Garnavich, Peter, E-mail: gmarion@cfa.harvard.edu [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); and others
2014-02-01
We report spectroscopic and photometric observations of the Type IIb SN 2011dh obtained between 4 and 34 days after the estimated date of explosion (May 31.5 UT). The data cover a wide wavelength range from 2000 Å in the ultraviolet (UV) to 2.4 μm in the near-infrared (NIR). Optical spectra provide line profiles and velocity measurements of H I, He I, Ca II, and Fe II that trace the composition and kinematics of the supernova (SN). NIR spectra show that helium is present in the atmosphere as early as 11 days after the explosion. A UV spectrum obtained with the Space Telescope Imaging Spectrograph reveals that the UV flux for SN 2011dh is low compared to other SN IIb. Modeling the spectrum with SYNOW suggests that the UV deficit is due to line blanketing from Ti II and Co II. The H I and He I velocities in SN 2011dh are separated by about 4000 km s{sup –1} at all phases. A velocity gap is consistent with models for a preexplosion structure in which a hydrogen-rich shell surrounds the progenitor. We estimate that the H shell of SN 2011dh is ≈8 times less massive than the shell of SN 1993J and ≈3 times more massive than the shell of SN 2008ax. Light curves (LCs) for 12 passbands are presented: UVW2, UVM2, UVW1, U, u', B, V, r', i', J, H, and K{sub s} . In the B band, SN 2011dh reached peak brightness of 13.17 mag at 20.0 ± 0.5 after the explosion. The maximum bolometric luminosity of 1.8 ± 0.2 × 10{sup 42} erg s{sup –1} occurred ≈22 days after the explosion. NIR emission provides more than 30% of the total bolometric flux at the beginning of our observations, and the NIR contribution increases to nearly 50% of the total by day 34. The UV produces 16% of the total flux on day 4, 5% on day 9, and 1% on day 34. We compare the bolometric LCs of SN 2011dh, SN 2008ax, and SN 1993J. The LC are very different for the first 12 days after the explosions, but all three SN IIb display similar peak luminosities, times of peak, decline rates, and
Litvinov, Rustem I; Mekler, Andrey; Shuman, Henry; Bennett, Joel S; Barsegov, Valeri; Weisel, John W
2012-10-12
Using a combined experimental and theoretical approach named binding-unbinding correlation spectroscopy (BUCS), we describe the two-dimensional kinetics of interactions between fibrinogen and the integrin αIIbβ3, the ligand-receptor pair essential for platelet function during hemostasis and thrombosis. The methodology uses the optical trap to probe force-free association of individual surface-attached fibrinogen and αIIbβ3 molecules and forced dissociation of an αIIbβ3-fibrinogen complex. This novel approach combines force clamp measurements of bond lifetimes with the binding mode to quantify the dependence of the binding probability on the interaction time. We found that fibrinogen-reactive αIIbβ3 pre-exists in at least two states that differ in their zero force on-rates (k(on1) = 1.4 × 10(-4) and k(on2) = 2.3 × 10(-4) μm(2)/s), off-rates (k(off1) = 2.42 and k(off2) = 0.60 s(-1)), and dissociation constants (K(d)(1) = 1.7 × 10(4) and K(d)(2) = 2.6 × 10(3) μm(-2)). The integrin activator Mn(2+) changed the on-rates and affinities (K(d)(1) = 5 × 10(4) and K(d)(2) = 0.3 × 10(3) μm(-2)) but did not affect the off-rates. The strength of αIIbβ3-fibrinogen interactions was time-dependent due to a progressive increase in the fraction of the high affinity state of the αIIbβ3-fibrinogen complex characterized by a faster on-rate. Upon Mn(2+)-induced integrin activation, the force-dependent off-rates decrease while the complex undergoes a conformational transition from a lower to higher affinity state. The results obtained provide quantitative estimates of the two-dimensional kinetic rates for the low and high affinity αIIbβ3 and fibrinogen interactions at the single molecule level and offer direct evidence for the time- and force-dependent changes in αIIbβ3 conformation and ligand binding activity, underlying the dynamics of fibrinogen-mediated platelet adhesion and aggregation.
Energy Technology Data Exchange (ETDEWEB)
Ferrigno, Robson [Fundacao Antonio Prudente, Sao Paulo, SP (Brazil). Hospital A.C. Camargo; Oliveira Faria, Sergio Luis Campos de [Pontificia Univ. Catolica de Campinas, SP (Brazil). Hospital Mario Gatti
1995-05-01
From September 1989 to December 1992, 178 patients with cervix cancer were treated with radiation therapy alone, being 81 stage IIIB patients were randomized according to the number of intracavitary brachytherapy insertion realized after external irradiation. Of these, 34 were treated with two intracavitary insertion (group A) and 47 with one insertion (group B). Among stage IIIB patients, 54 were treated with one intracavitary insertion after external irradiation (group C) and 47 with external irradiation alone as they had no geometrical condition for intracavitary insertion (group D). There were no statistical difference in 50 months disease free survival among patients stage IIB treated with one or two intracavitary insertion, 72,3% and 70.6% respectively (P=0,711). The 50 months disease free survival were better in patients stage IIIB treated with external irradiation followed by one intracavitary insertion, compared with those treated with external irradiation alone, 51,8% and 30,2% respectively (P=0,007). This series suggests that there is no difference in the treatment of stage IIB cervix cancer with one or two intracavitary insertion. Among stage IIIB patients, the worse result of those treated with external irradiation alone was probably due to the unfavorable prognostic factors, as they were excluded for brachytherapy because they showed no geometrical condition for intracavitary insertion and larger tumor volume. (author) 18 refs., 2 figs., 5 tabs.
Novel mutations of integrin αIIb and β3 genes in Turkish children with Glanzmann's thrombasthenia.
Tokgoz, Huseyin; Torun Ozkan, Didem; Caliskan, Umran; Akar, Nejat
2015-01-01
Glanzmann's thrombasthenia (GT) is an inherited disorder of platelet aggregation, characterized by qualitative and quantitative defect on platelet αIIbβ3 integrin (GpIIb/IIIa), resulting in lifelong bleeding tendency due to defective platelet plug formation. The αIIb gene (ITGA2B) and β3 gene (ITGB3) are closely located at chromosome 17q21.31-32. ITGA2B consist of 30 exons and encoding α chain, whereas ITGB3 has 15 exons and encoding β chain. Until now, according to the Human Gene Mutation Database (HGMD), 138 mutations at ITGA2B gene and 101 mutations at ITGB3 gene have been identified. We aimed to determine whether there was any mutation in the ITGA2B and ITGB3 genes, and a correlation between clinical phenotype and genotype in Turkish GT patients. We examined 20 patients with GT followed at the Department of Pediatric Hematology, Meram Faculty of Medicine, for Clinical and Laboratory Findings and Molecular Genetic Analysis. Peripheral blood was collected from patients, and a written informed consent for genetic analysis was obtained from parents. DNA was isolated from by proteinase K and phenol/chloroform extraction. ITGA2B and ITGB3 genes were screened by polymerase chain reaction. There were 12 females and 8 males with a median age of 15.25 years. Major clinical presentations of these patients were mucocutaneous bleedings. The most common bleeding type was epistaxis (85%). Life-threatening bleedings were seen in five patients. Seven (35%) patients showed various mutations in the ITGA2B or ITGB3 genes. We detected four novel mutations in three different regions and two mutations defined previously within the ITGA2B gene. These changes are at exon 4; c.570 T > G alteration, at exon 13 c.1277 T > A, c.1291 T > G alterations, at exon 19 c.1921A > G alterations. And from the start point of exon 14, behind 107 bases, we detected a heterozygous alteration at Thymine to Guanine. According to PolyPhen Database Program and NCBI Multiple Alignment Tool Database
Müller, Gerhard; Gurrath, Marion; Kessler, Horst
1994-12-01
Structurally guided design approaches to low-molecular-weight platelet aggregation antagonists addressing the platelet-associated heterodimeric cell surface receptor gpIIb/IIIa rely on comparative studies of an ensemble of conformationally and biologically characterized compounds, since no high-resolution structure of the receptor system is available. We report a classical indirect and comparative pharmacophore refinement approach based on a series of small cyclic Arg-Gly-Asp (RGD) peptides as gpIIb/IIIa-fibrinogen interaction antagonists. These peptides have previously been investigated as potent and selective tumor cell adhesion inhibitors. The definition of geometrical descriptors classifying the RGD peptide conformations and their subsequent analysis over selected RGD- and RXD-containing protein structures allows for a correlation of distinct structural features for platelet aggregation inhibition. An almost parallel alignment of the Arg and Asp side chains was identified by a vector analysis as being present in all active cyclic hexa-and pentapeptides. This orientation is induced mainly by the constraint of backbone cyclization and is not of any covalent tripeptide-inherent origin, which was rationalized by a 500 ps high-energy MD simulation of a sequentially related linear model peptide. The incorporation of the recognition tripeptide Arg-Gly-Asp into the cyclic peptide templates acted as a filter mechanism, restricting the otherwise free torsional relation of both side chains to a parallel orientation. Based on the derived results, several detailed features of the receptor binding site could be deduced in terms of receptor complementarity. These findings should govern the design of next-generation compounds with enhanced activities. Furthermore, the complementary stereochemical characteristics of the substrate can be used as boundary conditions for pseudoreceptor modelling studies that are capable of reconstructing a hypothetical binding pocket
Type II heat-labile enterotoxins (LT-II) have been reported in Escherichia coli isolates from humans, animals, food and water samples. The roles of the antigenically distinguishable LT-IIa and LT-IIb subtypes in pathogenesis and virulence of enterotoxigenic E. coli (ETEC) have not been previously re...
T. Bauer (Timm); H. Möllmann (Helge); F. Weidinger (Franz); U. Zeymer (Uwe); R. Seabra-Gomes (Ricardo); F.R. Eberli (Franz Robert); P.W.J.C. Serruys (Patrick); A. Vahanian (Alec); S. Silber (Sigmund); W. Wijns (William); M. Hochadel (Matthias); H.M. Nef (Holger); C.W. Hamm (Christian); J. Marco (Jean); A.K. Gitt (Anselm)
2010-01-01
textabstractBackground: The most recent ESC guidelines for percutaneous coronary intervention (PCI) recommend the use of glycoprotein IIb/IIIa inhibitors (GPI) in high risk patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS), particularly in diabetics. Little is known about th
Bui-Nguyen, B.; Butrynski, J. E.; Penel, N.; Blay, J. Y.; Isambert, N.; Milhem, M.; Kerst, J. M.; Reyners, A. K. L.; Litiere, S.; Marreaud, S.; Collin, F.; van der Graaf, W. T. A.
Purpose: To evaluate whether trabectedin as first-line chemotherapy for advanced/metastatic soft tissue sarcoma prolongs progression-free survival (PFS), compared to doxorubicin and, in the phase IIb part here, to select the most appropriate trabectedin treatment schedule (3-hour or 24-hour
Bui-Nguyen, B.; Butrynski, J.E.; Penel, N.; Blay, J.Y.; Isambert, N.; Milhem, M.; Kerst, J.M.; Reyners, A.K.; Litiere, S.; Marreaud, S.; Collin, F.; Graaf, W.T.A. van der
2015-01-01
PURPOSE: To evaluate whether trabectedin as first-line chemotherapy for advanced/metastatic soft tissue sarcoma prolongs progression-free survival (PFS), compared to doxorubicin and, in the phase IIb part here, to select the most appropriate trabectedin treatment schedule (3-hour or 24-hour
Arcavi, Iair; Yaron, Ofer; Sternberg, Assaf; Rabinak, Itay; Waxman, Eli; Kasliwal, Mansi M; Quimby, Robert M; Ofek, Eran O; Horesh, Assaf; Kulkarni, Shrinivas R; Filippenko, Alexei V; Silverman, Jeffrey M; Cenko, S Bradley; Li, Weidong; Bloom, Joshua S; Sullivan, Mark; Fox, Derek B; Nugent, Peter E; Poznanski, Dovi; Gorbikov, Evgeny; Riou, Amedee; Lamotte-Bailey, Stephane; Griga, Thomas; Cohen, Judith G; Polishook, David; Xu, Dong; Ben-Ami, Sagi; Manulis, Ilan; Walker, Emma S; Mazzali, Paulo A; Pian, Elena; Matheson, Thomas; Maquire, Kate; Pan, Yen-Chen; Bersier, David; James, Philip; Marchant, Jonathan M; Smith, Robert J; Mottram, Chris J; Barnsley, Robert M; Kandrashoff, Michael T; Clubb, Kelsey I
2011-01-01
On May 31, 2011 UT a supernova (SN) exploded in the nearby galaxy M51 (the Whirlpool Galaxy). We discovered this event using small telescopes equipped with CCD cameras, as well as by the Palomar Transient Factory (PTF) survey, and rapidly confirmed it to be a Type II supernova. Our early light curve and spectroscopy indicates that PTF11eon resulted from the explosion of a relatively compact progenitor star as evidenced by the rapid shock-breakout cooling seen in the light curve, the relatively low temperature in early-time spectra and the prompt appearance of low-ionization spectral features. The spectra of PTF11eon are dominated by H lines out to day 10 after explosion, but initial signs of He appear to be present. Assuming that He lines continue to develop in the near future, this SN is likely a member of the cIIb (compact IIb; Chevalier and Soderberg 2010) class, with progenitor radius larger than that of SN 2008ax and smaller than the eIIb (extended IIb) SN 1993J progenitor. Our data imply that the object...
K.M. Akkerhuis (Martijn); K.L. Neuhaus (Karl); R.G. Wilcox (Robert); A. Vahanian (Alec); J-L. Boland (Jean); J. Hoffmann; T. Baardman (Taco); G. Nehmiz; U. Roth; A.P.J. Klootwijk (Peter); J.W. Deckers (Jaap); M.L. Simoons (Maarten)
2000-01-01
textabstractAIMS: Oral glycoprotein IIb/IIIa inhibitors might enhance the early benefit of an intravenous agent and prevent subsequent cardiac events in patients with acute coronary syndromes. We assessed the safety and preliminary efficacy of 1 month treatment with three dose levels of the oral GP
Bui-Nguyen, B.; Butrynski, J. E.; Penel, N.; Blay, J. Y.; Isambert, N.; Milhem, M.; Kerst, J. M.; Reyners, A. K. L.; Litiere, S.; Marreaud, S.; Collin, F.; van der Graaf, W. T. A.
2015-01-01
Purpose: To evaluate whether trabectedin as first-line chemotherapy for advanced/metastatic soft tissue sarcoma prolongs progression-free survival (PFS), compared to doxorubicin and, in the phase IIb part here, to select the most appropriate trabectedin treatment schedule (3-hour or 24-hour infusion
Bui-Nguyen, B.; Butrynski, J.E.; Penel, N.; Blay, J.Y.; Isambert, N.; Milhem, M.; Kerst, J.M.; Reyners, A.K.; Litiere, S.; Marreaud, S.; Collin, F.; Graaf, W.T.A. van der
2015-01-01
PURPOSE: To evaluate whether trabectedin as first-line chemotherapy for advanced/metastatic soft tissue sarcoma prolongs progression-free survival (PFS), compared to doxorubicin and, in the phase IIb part here, to select the most appropriate trabectedin treatment schedule (3-hour or 24-hour infusion
DEFF Research Database (Denmark)
Stone, Gregg W; Mehran, Roxana; Goldstein, Patrick;
2015-01-01
bleeding and mortality rates, but higher acute stent thrombosis rates compared with heparin + a glycoprotein IIb/IIIa inhibitor (GPI). Subsequent changes in primary PCI, including the use of potent P2Y12 inhibitors, frequent radial intervention, and pre-hospital medication administration, were incorporated...... into the EUROMAX (European Ambulance Acute Coronary Syndrome Angiography) trial, which assigned 2,218 patients to bivalirudin versus heparin ± GPI before primary PCI. OBJECTIVES: The goal of this study was to examine the outcomes of procedural anticoagulation with bivalirudin versus heparin ± GPI for primary PCI......, given the evolution in primary PCI. METHODS: Databases from HORIZONS-AMI and EUROMAX were pooled for patient-level analysis. The Breslow-Day test evaluated heterogeneity between trials. RESULTS: A total of 5,800 patients were randomized to bivalirudin (n = 2,889) or heparin ± GPI (n = 2,911). The radial...
Capodagli, Glenn C; Lee, Stephen A; Boehm, Kyle J; Brady, Kristin M; Pegan, Scott D
2014-12-09
Staphylococcus aureus is one of the most common nosocomial sources of soft-tissue and skin infections and has more recently become prevalent in the community setting as well. Since the use of penicillins to combat S. aureus infections in the 1940s, the bacterium has been notorious for developing resistances to antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA). With the persistence of MRSA as well as many other drug resistant bacteria and parasites, there is a growing need to focus on new pharmacological targets. Recently, class II fructose 1,6-bisphosphate aldolases (FBAs) have garnered attention to fill this role. Regrettably, scarce biochemical data and no structural data are currently available for the class II FBA found in MRSA (SaFBA). With the recent finding of a flexible active site zinc-binding loop (Z-Loop) in class IIa FBAs and its potential for broad spectrum class II FBA inhibition, the lack of information regarding this feature of class IIb FBAs, such as SaFBA, has been limiting for further Z-loop inhibitor development. Therefore, we elucidated the crystal structure of SaFBA to 2.1 Å allowing for a more direct structural analysis of SaFBA. Furthermore, we determined the KM for one of SaFBA's substrates, fructose 1,6-bisphosphate, as well as performed mode of inhibition studies for an inhibitor that takes advantage of the Z-loop's flexibility. Together the data offers insight into a class IIb FBA from a pervasively drug resistant bacterium and a comparison of Z-loops and other features between the different subtypes of class II FBAs.
Energy Technology Data Exchange (ETDEWEB)
Oyen, W.J.G.; Boerman, O.C.; Corstens, F.H.M. [Department of Nuclear Medicine, University Hospital Nijmegen, Nijmegen (Netherlands); Brouwers, F.M. [Department of Nuclear Medicine, University Hospital Nijmegen, Nijmegen (Netherlands); Department of Internal Medicine, University Hospital Nijmegen, Nijmegen (Netherlands); Barrett, J.A. [DuPont Pharmaceutical Company, Radiopharmaceutical Division, North Billerica, MA (United States); Verheugt, F.W.A. [Department of Cardiology, University Hospital Nijmegen, Nijmegen (Netherlands); Ruiter, D.J. [Department of Pathology, University Hospital Nijmegen, Nijmegen (Netherlands); Meer, J.W.M. van der [Department of Internal Medicine, University Hospital Nijmegen, Nijmegen (Netherlands)
2000-04-01
Bacterial endocarditis is an important clinical problem that may result in persistent bacteraemia and irreversible cardiac damage. Since endocarditis is characterized by aggregation of activated platelets, fibrin and bacteria, we studied DMP444, a technetium-99m labelled high-affinity antagonist of the GP IIb/IIIa receptor that is expressed on activated platelets. In seven Beagle dogs (11-15 kg), the left ventricle was catheterized via the right carotid artery. One hour later, 5 x 10{sup 7} colony forming units of Staphylococcus aureus were injected intracardially. Half an hour later, the catheter was removed. Two extra dogs underwent a complete sham procedure. One day after the intervention, five infected and the two non-infected dogs were injected with 37 MBq/kg {sup 99m}Tc-DMP444 and two infected dogs with 37 MBq/kg {sup 99m}Tc-IgG (used as a non-specific control agent) and imaged up to 4 h after injection. Samples were obtained for tissue counting, microbiology and histology. From 1 to 2 h post injection onward, there was clear focal accumulation of DMP444 in the aortic valve region when endocarditis was present, and this accumulation increased with time. The non-infected and the {sup 99m}Tc-IgG injected dogs showed only persisting blood pool activity without any focal abnormality. At 4 h post injection, the in vivo valve-to-blood pool ratios were 1.87{+-}0.18 in endocarditis, 1.01{+-}0.05 in non-infected controls and 1.09{+-}0.02 in {sup 99m}Tc-IgG injected dogs (P<0.05). It is concluded that targeting activated platelets with the {sup 99m}Tc-labelled GP IIb/IIIa antagonist DMP444 allows a final diagnosis of experimental bacterial endocarditis within 4 h owing to high, specific and fast in vivo uptake. (orig.)
Zhi, Huiying; Dai, Jing; Liu, Junling; Zhu, Jieqing; Newman, Debra K; Gao, Cunji; Newman, Peter J
2015-01-01
IgG immune complexes contribute to the etiology and pathogenesis of numerous autoimmune disorders, including heparin-induced thrombocytopenia, systemic lupus erythematosus, rheumatoid- and collagen-induced arthritis, and chronic glomerulonephritis. Patients suffering from immune complex-related disorders are known to be susceptible to platelet-mediated thrombotic events. Though the role of the Fc receptor, FcγRIIa, in initiating platelet activation is well understood, the role of the major platelet adhesion receptor, integrin αIIbβ3, in amplifying platelet activation and mediating adhesion and aggregation downstream of encountering IgG immune complexes is poorly understood. The goal of this investigation was to gain a better understanding of the relative roles of these two receptor systems in immune complex-mediated thrombotic complications. Human platelets, and mouse platelets genetically engineered to differentially express FcγRIIa and αIIbβ3, were allowed to interact with IgG-coated surfaces under both static and flow conditions, and their ability to spread and form thrombi evaluated in the presence and absence of clinically-used fibrinogen receptor antagonists. Although binding of IgG immune complexes to FcγRIIa was sufficient for platelet adhesion and initial signal transduction events, platelet spreading and thrombus formation over IgG-coated surfaces showed an absolute requirement for αIIbβ3 and its ligands. Tyrosine kinases Lyn and Syk were found to play key roles in IgG-induced platelet activation events. Taken together, our data suggest a complex functional interplay between FcγRIIa, Lyn, and αIIbβ3 in immune complex-induced platelet activation. Future studies may be warranted to determine whether patients suffering from immune complex disorders might benefit from treatment with anti-αIIbβ3-directed therapeutics.
Directory of Open Access Journals (Sweden)
Huiying Zhi
Full Text Available IgG immune complexes contribute to the etiology and pathogenesis of numerous autoimmune disorders, including heparin-induced thrombocytopenia, systemic lupus erythematosus, rheumatoid- and collagen-induced arthritis, and chronic glomerulonephritis. Patients suffering from immune complex-related disorders are known to be susceptible to platelet-mediated thrombotic events. Though the role of the Fc receptor, FcγRIIa, in initiating platelet activation is well understood, the role of the major platelet adhesion receptor, integrin αIIbβ3, in amplifying platelet activation and mediating adhesion and aggregation downstream of encountering IgG immune complexes is poorly understood. The goal of this investigation was to gain a better understanding of the relative roles of these two receptor systems in immune complex-mediated thrombotic complications. Human platelets, and mouse platelets genetically engineered to differentially express FcγRIIa and αIIbβ3, were allowed to interact with IgG-coated surfaces under both static and flow conditions, and their ability to spread and form thrombi evaluated in the presence and absence of clinically-used fibrinogen receptor antagonists. Although binding of IgG immune complexes to FcγRIIa was sufficient for platelet adhesion and initial signal transduction events, platelet spreading and thrombus formation over IgG-coated surfaces showed an absolute requirement for αIIbβ3 and its ligands. Tyrosine kinases Lyn and Syk were found to play key roles in IgG-induced platelet activation events. Taken together, our data suggest a complex functional interplay between FcγRIIa, Lyn, and αIIbβ3 in immune complex-induced platelet activation. Future studies may be warranted to determine whether patients suffering from immune complex disorders might benefit from treatment with anti-αIIbβ3-directed therapeutics.
Directory of Open Access Journals (Sweden)
Christopher J Greene
Full Text Available Currently, there is a shortage of adjuvants that can be employed with protein subunit vaccines to enhance protection against biological threats. LT-IIb(T13I is an engineered nontoxic derivative of LT-IIb, a member of the type II subfamily of heat labile enterotoxins expressed by Escherichia coli, that possesses potent mucosal adjuvant properties. In this study we evaluated the capacity of LT-IIb(T13I to augment the potency of RiVax, a recombinant ricin toxin A subunit vaccine, when co-administered to mice via the intradermal (i.d. and intranasal (i.n. routes. We report that co-administration of RiVax with LT-IIb(T13I by the i.d. route enhanced the levels of RiVax-specific serum IgG antibodies (Ab and elevated the ratio of ricin-neutralizing to non-neutralizing Ab, as compared to RiVax alone. Protection against a lethal ricin challenge was also augmented by LT-IIb(T13I. While local inflammatory responses elicited by LT-IIb(T13I were comparable to those elicited by aluminum salts (Imject®, LT-IIb(T13I was more effective than aluminum salts at augmenting production of RiVax-specific serum IgG. Finally, i.n. administration of RiVax with LT-IIb(T13I also increased levels of RiVax-specific serum and mucosal Ab and enhanced protection against ricin challenge. Collectively, these data highlight the potential of LT-IIb(T13I as an effective next-generation i.d., or possibly i.n. adjuvant for enhancing the immunogenicity of subunit vaccines for biodefense.
Energy Technology Data Exchange (ETDEWEB)
Schmidberger, H. [Radiologische Universitaetsklinik Tuebingen (Germany). Abt. fuer Strahlentherapie; Bamberg, M. [Radiologische Universitaetsklinik Tuebingen (Germany). Abt. fuer Strahlentherapie
1995-03-01
Testicular seminoma in the early stages is treated with orchiectomy and radiotherapy to the retroperitoneal nodes. Despite the high cure rates of this treatment, there is an ongoing controversy concerning the extent of the radiation fields and the radiation doses to be given in the clinical stages I, IIA and IIB. In the present literature review, these controversial issues are discussed. Four hundred and ninety-one patients in stage I testicular seminoma received adjuvant paraaortic irradiation with a total dose of 26 Gy. Forty-one patients in stage IIA, and 19 patients in stage IIB received 30 Gy or 36 Gy respectively to the paraaortic and ipsilateral iliacal nodes. Paraaortic radiotherapy in stage I disease was associated with low acute side effects and a disease-free survival in 97.1% of the patients after a median observation of 13 months. In stage IIA the disease-free survival was 100%, in stage IIB 94.7%. The literature review and preliminary results of the reported ongoing trial are indicating that paraaortic irradiation in stage I and paraaortic with ipsilateral iliacal irradiation in stages IIA and IIB seem to be a sufficient treatment in early stage testicular seminoma with low treatment associated morbidity. (orig./MG) [Deutsch] Testikulaere Seminome in den fruehen Stadien werden nach der Semikastratio mit einer Radiatio der retroperitonealen Lymphknotenstationen behandelt. Trotz der hohen Heilungsraten dieser Behandlung bestehen kontroverse Ansichten sowohl ueber die adaequate Ausdehnung der Bestrahlungsfelder als auch ueber die Dosierung der Bestrahlung in den klinischen Stadien I, IIA und IIB. In dem vorliegenden Literaturueberblick werden diese kontroversen Standpunkte diskutiert. 491 Patienten mit testikulaeren Seminomen im Stadium I erhielten eine adjuvante Bestrahlung der Paraaortalregion mit einer Gesamtdosis von 26 Gy. 41 Patienten im Stadium IIA und 19 Patienten im Stadium IIB erhielten eine Bestrahlung mit jeweils 30 Gy bzw. 36 Gy auf die
2d (0,2) Quiver Gauge Theories and D-Branes
Franco, Sebastian; Lee, Sangmin; Seong, Rak-Kyeong; Yokoyama, Daisuke
2015-01-01
We initiate a systematic study of 2d (0,2) quiver gauge theories on the worldvolume of D1-branes probing singular toric Calabi-Yau 4-folds. We present an algorithm for efficiently calculating the classical mesonic moduli spaces of these theories, which correspond to the probed geometries. We also introduce a systematic procedure for constructing the gauge theories for arbitrary toric singularities by means of partial resolution, which translates to higgsing in the field theory. Finally, we introduce Brane Brick Models, a novel class of brane configurations that consist of D4-branes suspended from an NS5-brane wrapping a holomorphic surface, tessellating a 3-torus. Brane Brick Models are the 2d analogues of Brane Tilings and allow a direct connection between geometry and gauge theory.
Localized four-dimensional gravity in the D-brane background with NS $B$ field
Fonseca, R C; Losano, L
2016-01-01
We calculate small correction terms to gravitational potential near $p$-branes embedded in a constant NS $B$ field background in the context of M-theory or string theory. The normalizable wave functions of gravity fluctuations around the brane describe only massive modes. We compute such wave functions analytically. We estimate the correction to gravitational potential for small and long distances, and show that there is an intermediate range of distances in which we can identify $4D$ gravity on the brane below a crossover scale given in terms of components of the $B$ field. The $4D$ gravity is metastable and for distances much larger than the crossover scale the $5D$ gravity is recovered.
Isospin violating dark matter in Stückelberg portals with intersecting D-branes
Peiró, Miguel
2016-05-01
Certain string theory constructions are representative of the so-called hidden sector scenarios in which the hidden particles interact with the Standard Model matter fields through the exchange of massive Z‧ bosons. We show that such string motivated Stückelberg portals naturally lead to isospin violating interactions of DM particles with nuclei in direct detection experiments. We find that the ratios between the DM coupling to neutrons and protons for both, spin-independent (fn/fp ) and spin-dependent (an/ap ) interactions, are generically different from ±1, and depend on the charges of the quarks under the extra U(1) gauge groups. In order to find the experimentally allowed values of these ratios, we have incorporated constraints from searches for dijet and dilepton resonances at the LHC as well as LUX bounds on the elastic scattering of DM off nucleons. Our results highlight the importance of combining different search methods to shed light on this sort of scenarios.
Finite Temperature Corrections to Tachyon Mass in Intersecting D-Branes
Sethi, Varun; Sarkar, Swarnendu
2016-01-01
We continue with the analysis of finite temperature corrections to the Tachyon mass in intersecting branes which was initiated in arxiv:1403.0389. In this paper we extend the computation to the case of intersecting D3-branes by considering a setup of two intersecting branes in flat-space background. A holographic model dual to BCS superconductor consisting of intersecting D8-branes in D4-brane background was proposed in arxiv:1104.2843. The background considered here is a simplified configuration of this dual model. We compute the one-loop Tachyon amplitude in the Yang-Mills approximation and show that the result is finite. Analyzing the amplitudes further we numerically compute the transition temperature at which the Tachyon becomes massless. The analytic expressions for the one-loop amplitudes obtained here reduce to those for intersecting D1-branes obtained in arxiv:1403.0389 as well as those for intersecting D2-branes.
Microstates of D1–D5(-P black holes, as interacting D-branes
Directory of Open Access Journals (Sweden)
Takeshi Morita
2015-07-01
Full Text Available In our previous study (Morita et al., 2014 [1], we figured out that the thermodynamics of the near extremal black p-branes can be explained as the collective motions of gravitationally interacting elementary p-branes (the p-soup proposal. We test this proposal in the near-extremal D1–D5 and D1–D5-P black holes and show that their thermodynamics also can be explained in a similar fashion, i.e. via the collective motions of the interacting elementary D1-branes and D5-branes (and waves. It may imply that the microscopic origins of these intersecting black branes and the black p-brane are explained in the unified picture. We also argue the relation between the p-soup proposal and the conformal field theory calculations of the D1–D5(-P black holes in superstring theory.
Microstates of D1-D5(-P) black holes as interacting D-branes
Morita, Takeshi
2014-01-01
In our previous study [1] (1311.6540), we figured out that the thermodynamics of the near extremal black $p$-branes can be explained as the collective motions of gravitationally interacting elementary $p$-branes (the $p$-soup proposal). We test this proposal in the near-extremal D1-D5 and D1-D5-P black holes and show that their thermodynamics also can be explained in a similar fashion, i.e. via the collective motions of the interacting elementary D1-branes and D5-branes (and waves). It may imply that the microscopic origins of these intersecting black branes and the black $p$-brane are explained in the unified picture. We also argue the relation between the $p$-soup proposal and the conformal field theory calculations of the D1-D5(-P) black holes in superstring theory.
Microstates of D1-D5(-P) black holes, as interacting D-branes
Morita, Takeshi; Shiba, Shotaro
2015-07-01
In our previous study (Morita et al., 2014 [1]), we figured out that the thermodynamics of the near extremal black p-branes can be explained as the collective motions of gravitationally interacting elementary p-branes (the p-soup proposal). We test this proposal in the near-extremal D1-D5 and D1-D5-P black holes and show that their thermodynamics also can be explained in a similar fashion, i.e. via the collective motions of the interacting elementary D1-branes and D5-branes (and waves). It may imply that the microscopic origins of these intersecting black branes and the black p-brane are explained in the unified picture. We also argue the relation between the p-soup proposal and the conformal field theory calculations of the D1-D5(-P) black holes in superstring theory.
Microstates of D1–D5(-P) black holes, as interacting D-branes
Energy Technology Data Exchange (ETDEWEB)
Morita, Takeshi, E-mail: morita.takeshi@shizuoka.ac.jp [Department of Physics, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529 (Japan); Shiba, Shotaro, E-mail: sshiba@cc.kyoto-su.ac.jp [Maskawa Institute for Science and Culture, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-ku, Kyoto 603-8555 (Japan)
2015-07-30
In our previous study (Morita et al., 2014 [1]), we figured out that the thermodynamics of the near extremal black p-branes can be explained as the collective motions of gravitationally interacting elementary p-branes (the p-soup proposal). We test this proposal in the near-extremal D1–D5 and D1–D5-P black holes and show that their thermodynamics also can be explained in a similar fashion, i.e. via the collective motions of the interacting elementary D1-branes and D5-branes (and waves). It may imply that the microscopic origins of these intersecting black branes and the black p-brane are explained in the unified picture. We also argue the relation between the p-soup proposal and the conformal field theory calculations of the D1–D5(-P) black holes in superstring theory.
Solitons in Seiberg-Witten Theory and D-branes in the Derived Category
Aspinwall, Paul S; Aspinwall, Paul S.; Karp, Robert L.
2003-01-01
We analyze the "geometric engineering" limit of a type II string on a suitable Calabi-Yau threefold to obtain an N=2 pure SU(2) gauge theory. The derived category picture together with Pi-stability of B-branes beautifully reproduces the known spectrum of BPS solitons in this case in a very explicit way. Much of the analysis is particularly easy since it can be reduced to questions about the derived category of CP1.
2d (0,2) quiver gauge theories and D-branes
Energy Technology Data Exchange (ETDEWEB)
Franco, Sebastián [Physics Department, The City College of the CUNY,160 Convent Avenue, New York, NY 10031 (United States); The Graduate School and University Center, The City University of New York,365 Fifth Avenue, New York NY 10016 (United States); Ghim, Dongwook [Department of Physics and Astronomy, Seoul National University,Seoul 151-747 (Korea, Republic of); Lee, Sangmin [Department of Physics and Astronomy, Seoul National University,Seoul 151-747 (Korea, Republic of); Center for Theoretical Physics, Seoul National University,Seoul 151-747 (Korea, Republic of); College of Liberal Studies, Seoul National University,Seoul 151-742 (Korea, Republic of); School of Physics, Korea Institute for Advanced Study,Seoul 130-722 (Korea, Republic of); Seong, Rak-Kyeong [School of Physics, Korea Institute for Advanced Study,Seoul 130-722 (Korea, Republic of); Yokoyama, Daisuke [Department of Mathematics, King’s College London,The Strand, London WC2R 2LS (United Kingdom)
2015-09-14
We initiate a systematic study of 2d(0,2) quiver gauge theories on the worldvolume of D1-branes probing singular toric Calabi-Yau 4-folds. We present an algorithm for efficiently calculating the classical mesonic moduli spaces of these theories, which correspond to the probed geometries. We also introduce a systematic procedure for constructing the gauge theories for arbitrary toric singularities by means of partial resolution, which translates to higgsing in the field theory. Finally, we introduce Brane Brick Models, a novel class of brane configurations that consist of D4-branes suspended from an NS5-brane wrapping a holomorphic surface, tessellating a 3-torus. Brane Brick Models are the 2d analogues of Brane Tilings and allow a direct connection between geometry and gauge theory.
Nonlocal Effects on D-branes in Plane-Wave Backgrounds
Ganor, O J; Ganor, Ori J.; Varadarajan, Uday
2002-01-01
We argue that the effective field theory on D3-branes in a plane-wave background with 3-form flux is a nonlocal deformation of Yang-Mills theory. In the case of NSNS flux, it is a dipole field theory with lightlike dipole vectors. For an RR 3-form flux the dipole theory is strongly coupled. We propose a weakly coupled S-dual description for it. The S-dual description is local at any finite order in string perturbation theory but becomes nonlocal when all perturbation theory orders are summed together.
Radiative symmetry breaking on D-branes at non-supersymmetric singularities
Kitazawa, Noriaki
2006-10-01
The possibility of radiative gauge symmetry breaking on D3-branes at non-supersymmetric orbifold singularities is examined. As an example, a simple model of D3-branes at non-supersymmetric C/Z singularity with some D7-branes for the cancellations of RR tadpoles in twisted sectors is analyzed in detail. We find that there are no tachyon modes in twisted sectors, and NS-NS tadpoles in twisted sectors are canceled out, though uncanceled tadpoles and tachyon modes exist in untwisted sectors. This means that this singularity background is a stable solution of string theory at tree level, though some specific compactification of six-dimensional space should be considered for a consistent untwisted sector. On D3-brane three massless "Higgs doublet fields" and three family "up-type quarks" are realized at tree level. Other fermion fields, "down-type quarks" and "leptons", can be realized as massless modes of the open strings stretching between D3-branes and D7-branes. The Higgs doublet fields have Yukawa couplings with up-type quarks, and they also have self-couplings which give a scalar potential without flat directions. Since there is no supersymmetry, the radiative corrections may naturally develop negative Higgs mass squared and "electroweak symmetry breaking". We explicitly calculate the open string one-loop correction to the Higgs mass squared from twisted sectors, and find that the negative value is indeed realized in this specific model.
Radiative Symmetry Breaking on D-branes at Non-supersymmetric Singularities
Kitazawa, N
2006-01-01
The possibility of radiative gauge symmetry breaking on D3-branes at non-supersymmetric orbifold singularities is examined. As an example, a simple model of D3-branes at non-supersymmetric C^3/Z_6 singularity with some D7-branes for the cancellations of R-R tadpoles in twisted sectors is analyzed in detail. We find that there are no tachyon modes in twisted sectors, and NS-NS tadpoles in twisted sectors are canceled out, though uncanceled tadpoles and tachyon modes exist in untwisted sectors. This means that this singularity background is a stable solution of string theory at tree level, though some specific compactification of six-dimensional space should be considered for a consistent untwisted sector. On D3-brane three massless "Higgs doublet fields" and three family "up-type quarks" are realized at tree level. Other fermion fields, "down-type quarks" and "leptons", can be realized as massless modes of the open strings stretching between D3-branes and D7-branes. The Higgs doublet fields have Yukawa couplin...
Confining k-string tensions with D-Branes in Super Yang-Mills theories
Ridgway, Jefferson M
2008-01-01
We discuss confining k strings in four dimensional gauge theories using D5 branes in AdS5xS5, and D3 branes in Klebanov-Strassler and Maldacena-Nunez backgrounds. We present two results: The first that confining k string tensions in N=4 can be calculated using D5 branes in AdS5xS5 with a cut-off in the bulk AdS. Using an embedding of R2 times S4 in S5, we show that the D5 brane replicates a string of rank k in the antisymmetric representation. The second result shows that the S-Dual calculation to hep-th/0111078 reproduces the action in the Klebanov-Strassler and Maldacena-Nunez backgrounds exactly, while providing a more natural manifestation of the string charge k.
Seiberg duality for Chern-Simons quivers and D-brane mutations
Closset, Cyril
2012-03-01
Chern-Simons quivers for M2-branes at Calabi-Yau singularities are best understood as the low energy theory of D2-branes on a dual type IIA background. We show how the D2-brane point of view naturally leads to three dimensional Seiberg dualities for Chern-Simons quivers with chiral matter content: They arise from a change of brane basis (or mutation), in complete analogy with the better known Seiberg dualities for D3-brane quivers. This perspective reproduces the known rules for Seiberg dualities in Chern-Simons-Yang-Mills theories with unitary gauge groups. We provide explicit examples of dual theories for the quiver dual to the {Y^{{p,q}}}left( {mathbb{C}{mathbb{P}^{{2}}}} right) geometries. We also comment on the string theory derivation of CS quivers dual to massive type IIA geometries.
Seiberg duality for Chern-Simons quivers and D-brane mutations
Closset, Cyril
2012-01-01
Chern-Simons quivers for M2-branes at Calabi-Yau singularities are best understood as the low energy theory of D2-branes on a dual type IIA background. We show how the D2-brane point of view naturally leads to three dimensional Seiberg dualities for Chern-Simons quivers with chiral matter content: They arise from a change of brane basis (or mutation), in complete analogy with the better known Seiberg dualities for D3-brane quivers. This perspective reproduces the known rules for Seiberg dualities in Chern-Simons-Yang-Mills theories with unitary gauge groups. We provide explicit examples of dual theories for the quiver dual to the Y^{p,q}(CP^2) geometries. We also comment on the string theory derivation of CS quivers dual to massive type IIA geometries.
Realistic D-Brane Models on Warped Throats: Fluxes, Hierarchies and Moduli Stabilization
Cascales, J F G; Quevedo, Fernando; Uranga, Angel M
2004-01-01
We describe the construction of string theory models with semirealistic spectrum in a sector of (anti) D3-branes located at an orbifold singularity at the bottom of a highly warped throat geometry, which is a generalisation of the Klebanov-Strassler deformed conifold. These models realise the Randall-Sundrum proposal to naturally generate the Planck/electroweak hierarchy in a concrete string theory embedding, and yielding interesting chiral open string spectra. We describe examples with Standard Model gauge group (or left-right symmetric extensions) and three families of SM fermions, with correct quantum numbers including hypercharge. The dilaton and complex structure moduli of the geometry are stabilised by the 3-form fluxes required to build the throat. We describe diverse issues concerning the stabilisation of geometric Kahler moduli, like blow-up modes of the orbifold singularities, via D term potentials and gauge theory non-perturbative effects, like gaugino condensation. This local geometry, once embedd...
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Harskamp, Ralf E., E-mail: r.e.harskamp@gmail.com [Academic Medical Center–University of Amsterdam, Amsterdam (Netherlands); VU University Medical Center, Amsterdam (Netherlands); Duke Clinical Research Institute, Durham, NC (United States); Hoedemaker, Niels [Academic Medical Center–University of Amsterdam, Amsterdam (Netherlands); Newby, L. Kristin [Duke Clinical Research Institute, Durham, NC (United States); Woudstra, Pier; Grundeken, Maik J.; Beijk, Marcel A.; Piek, Jan J.; Tijssen, Jan G. [Academic Medical Center–University of Amsterdam, Amsterdam (Netherlands); Mehta, Rajendra H. [Duke Clinical Research Institute, Durham, NC (United States); Winter, Robbert J. de [Academic Medical Center–University of Amsterdam, Amsterdam (Netherlands)
2016-01-15
Background: Percutaneous coronary intervention (PCI) of saphenous vein grafts (SVG) poses a high-risk for distal coronary thromboembolic events. Glycoprotein IIb/IIIa inhibitors are frequently used in hope of reducing the impact of this, although the safety and efficacy of these drugs to improve outcomes in this setting are understudied. Methods: Patients were included if they had prior coronary artery bypass surgery and subsequently underwent PCI of ≥ 1 SVG graft at a Dutch academic center between 1997 and 2008. These patients were matched 1:1 based on peri-procedural use of abciximab using a propensity-score matching algorithm based on 17 variables. Conditional logistic regression and Cox regression stratified on matched pairs were performed to evaluate the association between abciximab use and MACCE (the composite measure of mortality, myocardial infarction, stroke and repeat revascularization) at 30 days and up to 1 year. Results: The composite of 30-day MACCE occurred in 18 patients (15.3%) in the abciximab group and 16 patients (13.6%) in the propensity matched control group (OR: 1.13, 95% CI: 0.57–2.21, p = 0.73). At 1-year follow-up, MACCE rates were also similar (32.5% vs. 33.9%, HR: 0.97, 95% CI: 0.59–1.59). Major bleeding (BARC types 3a–c) was higher in the abciximab group (11.9% vs. 4.2%, OR: 2.80, 95% CI: 1.01–7.77). Ischemic outcomes did not differ among patients with acute coronary syndromes. Conclusion: The use of intravenous abciximab was not associated with improved clinical outcomes up to 1-year among patients undergoing SVG PCI, but was related to more bleeding. - Highlights: • PCI of SVG poses a high-risk for distal coronary thromboembolic events. • Glycoprotein IIb/IIIa inhibitors are frequently used in an attempt to reduce this risk. • We evaluated the safety and efficacy of abciximab (a glycoprotein IIb/IIIa inhibitor) using a propensity-score matched analysis of 236 patients at a large academic medical center. • Thirty
Directory of Open Access Journals (Sweden)
Divyanshu Dubey
2014-01-01
Full Text Available Objectives: Retrospective pooled analysis of data from published prospective studies and randomized phase 1 and 2 trials was done to assess efficacy and safety profile of intravenous combination therapy [glycoprotein IIb/IIIa inhibitors and IV tissue plasminogen activator (tPA] in management of acute ischemic stroke. Materials and Methods: We searched Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, and EMBASE databases; two reviewers independently selected studies reporting safety endpoints and outcome measures in acute ischemic stroke patients treated with combination therapy. tPA arm of the National Institute of Neurological Disorders and Stroke (NINDS tPA trial was included in tPA-only group. Weighted means and proportions were calculated for numeric and categorical variables respectively. Bivariate analysis using Fisher′s exact test was done to compare baseline descriptors, safety endpoints, and outcome measures. Results: Combination therapy arm included 188 patients and IV tPA arm had 218 patients. Mean National Institutes of Health Stroke Scale (NIHSS in two groups were 12.8 and 14.6, respectively. Mean time-to-treatment was 2.3 hours in combination therapy arm and 2.55 hours in tPA arm. Treatment with combination therapy was associated with significant reduction in rate of symptomatic intracranial hemorrhage (sICH [odds ratio (OR 0.26, 95% cumulative incidence (CI 0.07 0.83, P value 0.01. Difference in better functional outcome at 90 days (OR 0.87, 95% CI 0.59-1.30, P value 0.54 and death at 90 days (OR 1.16, 95% CI 0.69-1.93, P value 0.60 were not significantly different in two groups. Conclusion: Combination of low dose IV TPA with glycoprotein IIb/IIIa inhibitors is associated with reduction in sICH rates in patients with acute ischemic stroke as compared to standard dose of IV tPA.
Relizani, Karima
2014-01-01
Myostatin, a growth factor of the TGF-β family that signals through the activin receptor-IIB (ActRIIB), has been identified as an important negative regulator of skeletal muscle growth. However, its effect on muscle energy metabolism and energy dependent muscle function remains largely unexplored. I here investigated the consequence of impaired ActRIIB signaling for muscle metabolism in two experimental models, i) the constitutive myostatin knockout mice and ii) following pharmacological admi...
Hamilton, M J D
2016-01-01
We review the actions of the supergravity theory in eleven dimensions as well as the type IIA and IIB supergravities in ten dimensions and derive the bosonic equations of motion in a coordinate-free notation. We also consider the existence of supersymmetries and the associated generalized Killing spinor equations. The aim of this note is to serve as a formulary and make the equations of supergravity more easily accessible to mathematicians.
Jerkstrand, A; Smartt, S J; Fransson, C; Sollerman, J; Taubenberger, S; Bersten, M; Spyromilio, J
2014-01-01
We investigate line formation processes in Type IIb supernovae (SNe) from 100 to 500 days post-explosion using spectral synthesis calculations. The modeling identifies the nuclear burning layers and physical mechanisms that produce the major emission lines, and the diagnostic potential of these. We compare the model calculations with data on the three best observed Type IIb SNe to-date - SN 1993J, SN 2008ax, and SN 2011dh. Oxygen nucleosynthesis depends sensitively on the main-sequence mass of the star and modeling of the [O I] 6300, 6364 lines constrains the progenitors of these three SNe to the M_ZAMS=12-16 M_sun range (ejected oxygen masses 0.3-0.9 M_sun), with SN 2011dh towards the lower end and SN 1993J towards the upper end of the range. The high ejecta masses from M_ZAMS >= 17 M_sun progenitors give rise to brighter nebular phase emission lines than observed. Nucleosynthesis analysis thus supports a scenario of low/moderate mass progenitors for Type IIb SNe, and by implication an origin in binary syste...
Directory of Open Access Journals (Sweden)
Ming Cheng
Full Text Available Structural and functional analyses of integrin αIIbβ3 has implicated swing-out motion of the β3 hybrid domain in αIIbβ3 activation and ligand binding. Using data from targeted molecular dynamics (TMD simulations, we engineered two disulfide-bonded mutant receptors designed to limit swing-out (XS-O. XS-O mutants cannot bind the high Mr ligand fibrinogen in the presence of an activating mAb or after introducing mutations into the αIIb subunit designed to simulate inside-out signaling. They also have reduced capacity to be "primed" to bind fibrinogen by pretreatment with eptifibatide. They can, however, bind the small RGD venom protein kistrin. Despite their inability to bind soluble fibrinogen, the XS-O mutants can support adhesion to immobilized fibrinogen, although such adhesion does not initiate outside-in signaling leading to normal cytoskeletal reorganization. Collectively, our data further define the biologic role of β3 hybrid domain swing-out in both soluble and immobilized high Mr ligand binding, as well as in priming and outside-in signaling. We also infer that swing-out is likely to be a downstream effect of receptor extension.
N=4 Supergravity Lagrangian for Type IIB on $T^{6/Z_{2}$ in Presence of Fluxes and D3-Branes
D'Auria, R; Gargiulo, F; Trigiante, M; Vaulà, Silvia; Auria, Riccardo D'; Ferrara, Sergio; Gargiulo, Floriana; Trigiante, Mario
2003-01-01
We derive the Lagrangian and the transformation laws of N=4 gauged supergravity coupled to matter multiplets whose sigma-model of the scalars is SU(1,1)/U(1)x SO(6,6+n)/SO(6)xSO(6+n) and which corresponds to the effective Lagrangian of the Type IIB string compactified on the T^6/Z_2 with fluxes turned on and in presence of n D3-branes. The gauge group is T^12x G where G is the gauge group on the brane and T^12 is the gauge group on the bulk corresponding to the gauged translations of the R-R scalars coming from the R-R four--form. The N=4 bulk sector of this theory can be obtained as a truncation of the Scherk-Schwarz spontaneously broken N=8 supergravity. Consequently the full bulk spectrum satisfies quadratic and quartic mass sum rules, identical to those encountered in Scherk-Schwarz reduction gauging a flat group. This theory gives rise to a no scale supergravity extended with partial super-Higgs mechanism.
Warped AdS6 × S 2 in Type IIB supergravity II: global solutions and five-brane webs
D'Hoker, Eric; Gutperle, Michael; Uhlemann, Christoph F.
2017-05-01
Motivated by the construction of holographic duals to five-dimensional superconformal quantum field theories, we obtain global solutions to Type IIB supergravity invariant under the superalgebra F (4) on a space-time of the form AdS6 × S 2 warped over a two-dimensional Riemann surface Σ. In earlier work, the general local solutions were expressed in terms of two locally holomorphic functions A ± on Σ and global solutions were sketched when Σ is a disk. In the present paper, the physical regularity conditions on the supergravity fields required for global solutions are implemented on A ± for arbitrary Σ. Global solutions exist only when Σ has a non-empty boundary ∂Σ. The differentials ∂ A ± are allowed to have poles only on ∂Σ and each pole corresponds to a semi-infinite ( p, q) five-brane. The construction for the disk is carried out in detail and the conditions for the existence of global solutions are articulated for surfaces with more than one boundary and higher genus.
Warped AdS{sub 6}×S{sup 2} in Type IIB supergravity I: local solutions
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D’Hoker, Eric; Gutperle, Michael [Department of Physics and Astronomy, University of California Los Angeles,405 Hilgard Avenue, Los Angeles, CA 90095-1547 (United States); Karch, Andreas; Uhlemann, Christoph F. [Department of Physics, University of Washington,P.O. Box 351560, Seattle, WA 98195-1560 (United States)
2016-08-05
We investigate the existence of solutions with 16 residual supersymmetries to Type IIB supergravity on a space-time of the form AdS{sub 6}×S{sup 2} warped over a two-dimensional Riemann surface Σ. The SO(2,5)×SO(3) isometry extends to invariance under the exceptional Lie superalgebra F(4). In the present paper, we construct the general Ansatz compatible with these symmetries, derive the corresponding reduced BPS equations, and obtain their complete local solution in terms of two locally holomorphic functions A{sub ±} on Σ, subject to certain positivity and regularity conditions. Globally, (A{sub +},A{sub −}) are allowed to be multiple-valued on Σ and be holomorphic sections of a holomorphic bundle over Σ with structure group contained in SU(1,1)×ℂ. Globally regular solutions are expected to provide the near-horizon geometry of (p,q) 5-brane and 7-brane webs which are holographic duals to five-dimensional conformal field theories. A preliminary analysis of the positivity and regularity conditions will be presented here, leaving the construction of globally regular solutions to a subsequent paper.
Extended no-scale structure and {alpha}'{sup 2} corrections to the type IIB action
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Pedro, F.G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Rummel, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Hong Kong Univ. of Science and Technology (China). Inst. for Advanced Study; Westphal, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kavali Institute for Theoretical Physics, Santa Barbara, CA (United States)
2013-06-15
We analyse a new N=1 string tree level correction at O({alpha}'{sup 2}) to the Kaehler potential of the volume moduli of type IIB Calabi-Yau flux compactification found recently by T. W. Grimm, R. Savelli and M. Weissenbacher (arXiv:1303.3317 [hep-th]) and its impact on the moduli potential. We find that it imposes a strong lower bound the Calabi-Yau volume in the Large Volume Scenario of moduli stabilisation. For KKLT-like scenarios we find that consistency of the action imposes an upper bound on the flux superpotential vertical stroke W{sub 0} vertical stroke