The N=1 effective actions of D-branes in Type IIA and IIB orientifolds
International Nuclear Information System (INIS)
Grimm, Thomas W.; Vieira Lopes, Daniel
2012-01-01
We discuss the four-dimensional N=1 effective actions of single space-time filling Dp-branes in general Type IIA and Type IIB Calabi-Yau orientifold compactifications. The effective actions depend on an infinite number of normal deformations and gauge connection modes. For D6-branes the N=1 Kähler potential, the gauge-coupling function, the superpotential and the D-terms are determined as functions of these fields. They can be expressed as integrals over chains which end on the D-brane cycle and a reference cycle. The infinite deformation space will reduce to a finite dimensional moduli space of special Lagrangian submanifolds upon imposing F- and D-term supersymmetry conditions. We show that the Type IIA moduli space geometry is captured by three real functionals encoding the deformations of special Lagrangian submanifolds, holomorphic three-forms and Kähler two-forms of Calabi-Yau manifolds. These elegantly combine in the N=1 Kähler potential, which reduces after applying mirror symmetry to the results previously determined for space-time filling D3-, D5- and D7-branes. We also propose general chain integral expressions for the Kähler potentials of Type IIB D-branes.
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.)
Type IIB orientifolds, D-brane instantons and the large volume scenario
International Nuclear Information System (INIS)
Plauschinn, Erik
2009-01-01
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.)
Supersymmetric Orientifolds with D-branes at angles
International Nuclear Information System (INIS)
Schreyer, R.
2001-12-01
We show the construction and detailed calculation of N = 1 supersymmetric orientifold compactifications of type IIB string theory to six dimensions and type IIA string theory to four dimensions. The orbifold group in the six dimensional models is Z N and in the four dimensional models Z N x Z M . In addition, worldsheet parity Ω in combination with the complex conjugation R in the compact directions, which are chosen to be direct products of two-tori, is modded out. This naturally leads to the inclusion of D-branes intersecting at angles in the compact directions. Gauge theories are known to live on the worldvolume of D-branes and chiral fermions are expected to be localized at the intersection points. This opens up the possibility to construct new phenomenologically interesting compactifications of string theory. However, the four dimensional models under consideration lead to non-chiral spectra. This is a consequence of the symmetric choice of placing the D-branes on top of the orientifold fixed planes. Nevertheless, a generalization of our model presented in the recent literature has led to a N = 1 supersymmetric compactification to four dimensions including the SM gauge group and three families of chiral fermions. As a more formal aspect, we focus on the case of Z 2 in the six dimensional and Z 2 x Z 2 in the four dimensional ΩR orientifolds to explicitely present models T-dual to known Ω orientifolds. The equivalence of the massless spectra is verified. In addition to the standard consistency conditions from tadpole cancellation, we obtain constraints for some of the models from worldsheet duality using the boundary state formalism. (orig.)
Canonical formulation of IIB D-branes
International Nuclear Information System (INIS)
Kamimura, K.
1998-01-01
We find Wess-Zumino actions for kappa invariant type IIB D-branes in explicit forms. A simple and compact expression is obtained by the use of spinor variables which are defined as power series of differential forms. Using the Wess-Zumino actions we develop the canonical formulation and find the complete set of the constraint equations for generic type IIB Dp-branes. The conserved global supersymmetry charges are determined and the algebra containing the central charges can be obtained explicitly. (orig.)
Orientifolds and D-branes in N=2 gauged linear sigma models
Brunner, Ilka
We study parity symmetries and boundary conditions in the framework of gauged linear sigma models. This allows us to investigate the Kaehler moduli dependence of the physics of D-branes as well as orientifolds in a Calabi-Yau compactification. We first determine the parity action on D-branes and define the set of orientifold-invariant D-branes in the linear sigma model. Using probe branes on top of orientifold planes, we derive a general formula for the type (SO vs Sp) of orientifold planes. As applications, we show how compactifications with and without vector structure arise naturally at different real slices of the Kaehler moduli space of a Calabi-Yau compactification. We observe that orientifold planes located at certain components of the fixed point locus can change type when navigating through the stringy regime.
Orientifold Planes, Type I Wilson Lines and Non-BPS D-branes
International Nuclear Information System (INIS)
Hyakutake, Y.; Imamura, Y.; Sugimoto, S.
2000-01-01
There is a longstanding puzzle concerned with the existence of Op-planes with p≥6, which are orientifold p-planes of negative charge with stuck Dp-branes. We study the consistency of configurations with various orientifold planes and propose a resolution to this puzzle. It is argued that O6-planes are possible in massive IIA theory with odd cosmological constant, while O7-planes and O8-planes are not allowed. Various relations between orientifold planes and non-BPS D-branes are also addressed. (author)
Orientifold Planes, Type I Wilson Lines and Non-BPS D-branes
Hyakutake, Yoshifumi; Imamura, Yosuke; Sugimoto, Shigeki
2000-01-01
There is a longstanding puzzle concerned with the existence of Op~-planes with p>=6, which are orientifold p-planes of negative charge with stuck Dp-branes. We study the consistency of configurations with various orientifold planes and propose a resolution to this puzzle. It is argued that O6~-planes are possible in massive IIA theory with odd cosmological constant, while O7~-planes and O8~-planes are not allowed. Various relations between orientifold planes and non-BPS D-branes are also addr...
Moduli stabilization in type IIB orientifolds
International Nuclear Information System (INIS)
Schulgin, W.
2007-01-01
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 6-II and Z 2 x Z 4 orientifolds
GUTs in type IIB orientifold compactifications
International Nuclear Information System (INIS)
Blumenhagen, Ralph; Braun, Volker; Grimm, Thomas W.; Weigand, Timo
2009-01-01
We systematically analyse 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 realisation 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 1,1,1,6,9 [18] and of the Quintic P 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 realise other phenomenological features such as the 10105 H Yukawa coupling and comment on the possibility of moduli stabilisation, 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.
GUTs on Compact Type IIB Orientifolds
Energy Technology Data Exchange (ETDEWEB)
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.
Flipped SU(5) from D-branes with type IIB fluxes
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Chen Chingming [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States)]. E-mail: cchen@physics.tamu.edu; Mayes, V.E. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States)]. E-mail: eric@physics.tamu.edu; Nanopoulos, D.V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States) and Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, TX 77381 (United States) and Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens 10679 (Greece)]. E-mail: dimitri@physics.tamu.edu
2006-02-16
We construct flipped SU(5) GUT models as type IIB flux vacua on Z{sub 2}xZ{sub 2} orientifolds. Turning on supergravity self-dual NSNS and RR three-form fluxes fixes the toroidal complex structure moduli and the dilaton. We give a specific example of a three-generation flipped SU(5) model with a complete Higgs sector where supersymmetry is softly broken by the supergravity fluxes in the closed string sector. All of the required Yukawa couplings are present if global U(1) factors resulting from a generalized Green-Schwarz mechanism are broken spontaneously or by world-sheet instantons. In addition, the model contains extra chiral and vector-like matter, potentially of mass O(M{sub string}) via trilinear superpotential couplings.
The D-instanton and other supersymmetric D-branes in IIB plane-wave string theory
International Nuclear Information System (INIS)
Gaberdiel, Matthias R.; Green, Michael B.
2003-01-01
A class of D-branes for the type IIB plane-wave background is considered that preserve half the dynamical supersymmetries of the light-cone gauge. The D-branes of this type are the Euclidean (or instantonic) (0,0), (0,4), and (4,0) branes (where (r,s) denotes a brane oriented with r axes in the first four directions transverse to the +, - light-cone, and s axes in the second four directions). Corresponding Lorentzian D-branes are (+,-;0,0), (+,-;0,4), and (+,-;4,0). These are constructed in two ways. The first uses a boundary state formalism which implements appropriate fermionic gluing conditions and the second is based on a direct quantization of the open strings ending on the branes. In distinction to the D-branes considered earlier these have massless world-volume fermions but do not possess kinematical supersymmetries. Cylinder diagrams describing the overlap between a pair of boundary states displaced by some distance are evaluated. The open-string description of this system involves mode frequencies that are, in general, given by irrational solutions to transcendental equations. The closed-string and open-string descriptions are shown to be equivalent by a nontrivial implementation of the S modular transformation. A classical description of the D-instanton (the (0,0) case) in light-cone gauge is also given
International Nuclear Information System (INIS)
Okuda, Takuya; Takayanagi, Tadashi
2006-01-01
We define a ghost D-brane in superstring theories as an object that cancels the effects of an ordinary D-brane. The supergroups U(N|M) and OSp(N/M) arise as gauge symmetries in the supersymmetric world-volume theory of D-branes and ghost D-branes. A system with a pair of D-brane and ghost D-brane located at the same location is physically equivalent to the closed string vacuum. When they are separated, the system becomes a new brane configuration. We generalize the type I/heterotic duality by including n ghost D9-branes on the type I side and by considering the heterotic string whose gauge group is OSp(32+2n/2n). Motivated by the type IIB S-duality applied to D9- and ghost D9-branes, we also find type II-like closed superstrings with U(n/n) gauge symmetry
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Everett, L.; Kane, G.L.; King, S.F.
2000-01-01
We examine the flavor structure of the trilinear superpotential couplings which can result from embedding the Standard Model within D-brane sectors in Type IIB orientifold models, which are examples within the Type I string framework. We find in general that the allowed flavor structures of the Yukawa coupling matrices to leading order are given by basic variations on the d emocratic'' texture ansatz. In certain interesting cases, the Yukawa couplings have a novel structure in which a single right-handed fermion couples democratically at leading order to three left-handed fermions. We discuss the viability of such a s ingle right-handed democracy'' in detail; remarkably, even though there are large mixing angles in the u,d sectors separately, the CKM mixing angles are small. The analysis demonstrates the ways in which the Type I superstring framework can provide a rich setting for investigating novel resolutions to the flavor puzzle. (author)
International Nuclear Information System (INIS)
Bagnoud, Maxime; Carlevaro, Luca
2006-01-01
We study T 11-D-q x T q /Z n orbifold compactifications of eleven-dimensional supergravity and M-theory using a purely algebraic method. Given the description of maximal supergravities reduced on square tori as non-linear coset σ-models, we exploit the mapping between scalar fields of the reduced theory and directions in the tangent space over the coset to construct the orbifold action as a non-Cartan preserving finite order inner automorphism of the complexified U-duality algebra. Focusing on the exceptional serie of Cremmer-Julia groups, we compute the residual U-duality symmetry after orbifold projection and determine the reality properties of their corresponding Lie algebras. We carry out this analysis as far as the hyperbolic e 10 algebra, conjectured to be a symmetry of M-theory. In this case the residual subalgebras are shown to be described by a special class of Borcherds and Kac-Moody algebras, modded out by their centres and derivations. Furthermore, we construct an alternative description of the orbifold action in terms of equivalence classes of shift vectors, and, in D 1, we show that a root of e 10 can always be chosen as the class representative. Then, in the framework of the E 10/10 /K(E 10/10 ) effective σ-model approach to M-theory near a spacelike singularity, we identify these roots with brane configurations stabilizing the corresponding orbifolds. In the particular case of Z 2 orbifolds of M-theory descending to type 0' orientifolds, we argue that these roots can be interpreted as pairs of magnetized D9- and D9'-branes, carrying the lower-dimensional brane charges required for tadpole cancellation. More generally, we provide a classification of all such roots generating Z n product orbifolds for n≤6, and hint at their possible interpretation
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
Applications of the D-instanton calculus in type IIB orientifold compactifications
International Nuclear Information System (INIS)
Moster, Sebastian
2010-01-01
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 11 GeV, but at 10 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 completely from the MSSM
On four-derivative terms in IIB Calabi-Yau orientifold reductions
Energy Technology Data Exchange (ETDEWEB)
Weissenbacher, Matthias [Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo,Kashiwa-no-ha 5-1-5, 277-8583 (Japan)
2017-04-11
We perform a Kaluza-Klein reduction of IIB supergravity including purely gravitational α{sup ′3}-corrections on a Calabi-Yau threefold, and perform the orientifold projection accounting for the presence of O3/O7-planes. We consider infinitesimal Kähler 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 Kähler moduli fields in the four-dimensional effective supergravity theory, which are referred to as friction couplings in the context of inflation.
On D-brane dynamics and moduli stabilization
Kitazawa, Noriaki
2017-09-01
We discuss the effect of the dynamics of D-branes on moduli stabilization in type IIB string theory compactifications, with reference to a concrete toy model of T6/Z 3 orientifold compactification with fractional D3-branes and anti-D3-branes at orbifold fixed points. The resulting attractive forces between anti-D3-branes and D3-branes, together with the repulsive forces between anti-D3-branes and O3-planes, can affect the stability of the compact space. There are no complex structure moduli in T6/Z 3 orientifold, which should thus capture some generic features of more general settings where all complex structure moduli are stabilized by three-form fluxes. The simultaneous presence of branes and anti-branes brings along the breaking of supersymmetry. Non-BPS combinations of this type are typical of “brane supersymmetry breaking” and are a necessary ingredient in the KKLT scenario for stabilizing the remaining Kähler moduli. The conclusion of our analysis is that, while mutual D-brane interactions sometimes help Kähler moduli stabilization, this is not always the case.
International Nuclear Information System (INIS)
Nakamura, Shin
2005-01-01
We propose a new method to describe a recoiling D-brane that is elastically scattered by closed strings in the nonrelativistic region. We utilize the low-energy effective field theory on the worldvolume of the D-brane, and the velocity of the D-brane is described by the time derivative of the expectation values of the massless scalar fields on the worldvolume. The effects of the closed strings are represented by a source term for the massless fields in this method. The momentum conservation condition between the closed strings and the D-brane is derived up to the relative sign of the momentum of the D-brane
Anomalies and inflow on D-branes and O-planes
International Nuclear Information System (INIS)
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 intersections, 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
K-theory, reality, and orientifolds
International Nuclear Information System (INIS)
Gukov, S.
2000-01-01
We use equivariant K-theory to classify charges of new (possibly non-supersymmetric) states localized on various orientifolds in type II string theory. We also comment on the stringy construction of new D-branes and demonstrate the discrete electric-magnetic duality in type I brane systems with p+q=7, as proposed by Witten. (orig.)
Aspects of string theory compactifications. D-brane statistics and generalised geometry
Energy Technology Data Exchange (ETDEWEB)
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
Aspects of string theory compactifications. D-brane statistics and generalised geometry
International Nuclear Information System (INIS)
Gmeiner, F.
2006-01-01
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
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.
Orientifolds and duality cascades: confinement before the wall
Argurio, Riccardo; Bertolini, Matteo
2018-02-01
We consider D-branes at orientifold singularities and discuss two properties of the corresponding low energy four-dimensional effective theories which are not shared, generically, by other Calabi-Yau singularities. The first property is that duality cascades are finite and, unlike ordinary ones, do not require an infinite number of degrees of freedom to be UV-completed. The second is that orientifolds tend to stabilize runaway directions. These two properties can have interesting implications and widen in an intriguing way the variety of gauge theories one can describe using D-branes.
The supergravity fields for a D-brane with a travelling wave from string amplitudes
International Nuclear Information System (INIS)
Black, William; Russo, Rodolfo; 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 xS 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.
Phenomenological aspects of D-branes
International Nuclear Information System (INIS)
Quevedo, F.
2003-01-01
A general overview is presented on string phenomenology, emphasizing the role played by D-branes. A general discussion of the main challenges for string phenomenology is followed by recent progress made in constructing realistic models from D-branes and anti-branes at singularities and also from intersecting D-branes. Some possible cosmological implications of these classes of string models are also mentioned. (author)
Phenomenological aspects of D-branes
Energy Technology Data Exchange (ETDEWEB)
Quevedo, F [Centre for Mathematical Sciences, DAMTP, University of Cambridge, Cambridge (United Kingdom)
2003-08-15
A general overview is presented on string phenomenology, emphasizing the role played by D-branes. A general discussion of the main challenges for string phenomenology is followed by recent progress made in constructing realistic models from D-branes and anti-branes at singularities and also from intersecting D-branes. Some possible cosmological implications of these classes of string models are also mentioned. (author)
Kaste, P.; Lutken, C.A.; Walcher, Johannes
2000-01-01
B-type D-branes are constructed on two different K3-fibrations over IP_1 using boundary conformal field theory at the rational Gepner points of these models. The microscopic CFT charges are compared with the Ramond charges of D-branes wrapped on holomorphic cycles of the corresponding Calabi-Yau manifold. We study in particular D4-branes and bundles localized on the K3 fibers, and find agreement with expectations. This provides a further test of the boundary CFT approach to $D$-brane physics.
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.
Progress in D-brane model building
International Nuclear Information System (INIS)
Marchesano, F.
2007-01-01
The state of the art in D-brane model building is briefly reviewed, focusing on recent achievements in the construction of D=4 N=1 type II string vacua with semi-realistic gauge sectors. Such progress relies on a better understanding of the spectrum of BPS D-branes, the effective field theory obtained from them and the explicit construction of vacua. We first consider D-branes in standard Calabi-Yau compactifications, and then the more involved case of compactifications with fluxes. We discuss how the non-trivial interplay between D-branes and fluxes modifies the previous model-building rules, as well as provides new possibilities to connect string theory to particle physics. (Abstract Copyright [2007], Wiley Periodicals, Inc.)
D-branes in little string theory
International Nuclear Information System (INIS)
Israel, Dan; Pakman, Ari; Troost, Jan
2005-01-01
We analyze in detail the D-branes in the near-horizon limit of NS5-branes on a circle, the holographic dual of little string theory in a double scaling limit. We emphasize their geometry in the background of the NS5-branes and show the relation with D-branes in coset models. The exact one-point functions giving the coupling of the closed string states with the D-branes and the spectrum of open strings are computed. Using these results, we analyze several aspects of Hanany-Witten setups, using exact CFT analysis. In particular we identify the open string spectrum on the D-branes stretched between NS5-branes which confirms the low-energy analysis in brane constructions, and that allows to go to higher energy scales. As an application we show the emergence of the beta-function of the N=2 gauge theory on D4-branes stretching between NS5-branes from the boundary states describing the D4-branes. We also speculate on the possibility of getting a matrix model description of little string theory from the effective theory on the D1-branes. By considering D3-branes orthogonal to the NS5-branes we find a CFT incarnation of the Hanany-Witten effect of anomalous creation of D-branes. Finally we give an brief description of some non-BPS D-branes
Statistical anisotropy from vector curvaton in D-brane inflation
International Nuclear Information System (INIS)
Dimopoulos, Konstantinos; Wills, Danielle; Zavala, Ivonne
2013-01-01
We investigate the possibility of embedding the vector curvaton paradigm in D-brane models of inflation in type IIB string theory in a simple toy model. The vector curvaton is identified with the U(1) gauge field that lives on the world volume of a D3-brane, which may be stationary or undergoing general motion in the internal space. The dilaton is considered as a spectator field which modulates the evolution of the vector field. In this set-up, the vector curvaton is able to generate measurable statistical anisotropy in the spectrum and bispectrum of the curvature perturbation assuming that the dilaton evolves as e −φ ∝a 2 where a(t) is the scale factor. Our work constitutes a first step towards exploring how such distinctive features may arise from the presence of several light fields that naturally appear in string theory models of cosmology.
International Nuclear Information System (INIS)
Kaste, P.; Lerche, W.; Luetken, C.A.; Walcher, J.
2000-01-01
B-type D-branes are constructed on two different K3-fibrations over P 1 using boundary conformal field theory at the rational Gepner points of these models. The microscopic CFT charges are compared with the Ramond charges of D-branes wrapped on holomorphic cycles of the corresponding Calabi-Yau manifold. We study in particular D4-branes and bundles localized on the K3 fibers, and find from CFT that each irreducible component of a bundle on K3 gains one modulus upon fibration over P 1 . This is in agreement with expectations and so provides a further test of the boundary CFT approach to D-brane physics
Moshe RozaliDepartment of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Darren Smyth(Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada)
2014-01-01
We discuss finite density configurations on probe D-branes, in the presence of worldvolume fermions. To this end we consider a phenomenological model whose bosonic sector is governed by the DBI action, and whose charged sector is purely fermionic. In this model, we demonstrate the existence of a compact worldvolume embedding, stabilized by a Fermi surface on the D- brane. The finite density state in the boundary QFT is a Fermi-like liquid. We comment on the possibility of realizing non-Fermi ...
Generalized N=1 orientifold compactifications and the Hitchin functionals
International Nuclear Information System (INIS)
Benmachiche, I.; Hamburg Univ.; Grimm, T.W.
2006-02-01
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.)
Generalized N=1 orientifold compactifications and the Hitchin functionals
International Nuclear Information System (INIS)
Benmachiche, Iman; Grimm, Thomas W.
2006-01-01
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 Kahler 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)xSU(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)xSU(3) structure manifolds. Evidence for this identification is provided by comparing the generalized type IIA and type IIB superpotentials
Indian Academy of Sciences (India)
string theory, and then describe two ecent attempts using D-branes. The first ... ification of the theory Å =T 6/G, where G =G1 +ΩG2 with G1 2 discrete internal sym- ... Whereas in the latter case anomalousU(1) factors in the gauge group disap-.
International Nuclear Information System (INIS)
Alberghi, Gian Luigi; Caceres, Elena; Goldstein, Kevin; Lowe, David A. . lowe@het.brown.edu
2001-08-01
We present a candidate supergravity solution for a stacked configuration of stable non-BPS D-branes in Type II string theory compactified on T 4 /Z 2 . This gives a supergravity description of nonabelian tachyon condensation on the brane woldvolume. (author)
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
D-branes, orbifolds, and Ext groups
International Nuclear Information System (INIS)
Katz, Sheldon; Pantev, Tony; Sharpe, Eric
2003-01-01
In this note we extend previous work on massless Ramond spectra of open strings connecting D-branes wrapped on complex manifolds, to consider D-branes wrapped on smooth complex orbifolds. Using standard methods, we calculate the massless boundary Ramond sector spectra directly in BCFT, and find that the states in the spectrum are counted by Ext groups on quotient stacks (which provide a notion of homological algebra relevant for orbifolds). Subtleties that cropped up in our previous work also appear here. We also use the McKay correspondence to relate Ext groups on quotient stacks to Ext groups on (large radius) resolutions of the quotients. As stacks are not commonly used in the physics community, we include pedagogical discussions of some basic relevant properties of stacks
Schimmrigk, Rolf
2012-01-01
In this paper the problem of constructing spacetime from string theory is addressed in the context of D-brane physics. It is suggested that the knowledge of discrete configurations of D-branes is sufficient to reconstruct the motivic building blocks of certain Calabi-Yau varieties. The collections of D-branes involved have algebraic base points, leading to the notion of K-arithmetic D-crystals for algebraic number fields K. This idea can be tested for D0-branes in the framework of toroidal compactifications via the conjectures of Birch and Swinnerton-Dyer. For the special class of D0-crystals of Heegner type these conjectures can be interpreted as formulae that relate the canonical Neron-Tate height of the base points of the D-crystals to special values of the motivic L-function at the central point. In simple cases the knowledge of the D-crystals of Heegner type suffices to uniquely determine the geometry.
Gauge and gravitational anomalies in D=4 N=1 orientifolds.
S Scrucca, C.; Serone, M.
1999-01-01
We analyze in detail the cancellation of U(1)-gauge and U(1)-gravitational anomalies in certain D=4 N=1 Type IIB orientifolds, from a string theory point of view. We verify the proposal that these anomalies are cancelled by a Green-Schwarz mechanism involving only twisted RR fields.By factorizing
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.
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
International Nuclear Information System (INIS)
Mukhopadhyay, Partha
2005-01-01
Non-BPS D-branes are difficult to describe covariantly 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 with manifest SO(8) covariance 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 functions without boundary insertions. This prescription has been tested by computing disk one-point functions of several classes of closed string states and comparing the results with the boundary state computation. (author)
Noncommutative D-branes from covariant AdS superstring
International Nuclear Information System (INIS)
Sakaguchi, Makoto; Yoshida, Kentaroh
2008-01-01
We study noncommutative (NC) D-branes on AdS 5 xS 5 from κ-invariance of covariant Green-Schwarz action of an open string with a non-trivial world-volume flux. Finding boundary conditions to ensure the κ-invariance, we can see possible configurations of the NC D-branes. With this method 1/4 BPS NC D-branes are discussed. The resulting NC Dp-branes are 1/4 BPS at arbitrary position other than the p=1 case. The exceptional D-string is 1/2 BPS at the origin and 1/4 BPS outside the origin. Those are reduced to possible 1/4 BPS or 1/2 BPS AdS D-branes in the commutative limit. The same analysis is applied to an open superstring in a pp-wave and leads to 1/4 BPS configurations of NC D-branes. These D-branes are consistently obtained from AdS D-branes via the Penrose limit
D-Branes in the Background of NS Fivebranes
Elitzur, Shmuel; Rabinovici, Eliezer; Sarkisian, G; Kutasov, D; Elitzur, Shmuel; Giveon, Amit; Kutasov, David; Rabinovici, Eliezer; Sarkissian, Gor
2000-01-01
We study the dynamics of $D$-branes in the near-horizon geometry of $NS$ fivebranes. This leads to a holographically dual description of the physics of $D$-branes ending on and/or intersecting $NS5$-branes. We use it to verify some properties of such $D$-branes which were deduced indirectly in the past, and discuss some instabilities of non-supersymmetric brane configurations. Our construction also describes vacua of Little String Theory which are dual to open plus closed string theory in asymptotically linear dilaton spacetimes.
Multifield consequences for D-brane inflation
Energy Technology Data Exchange (ETDEWEB)
Dias, Mafalda; Frazer, Jonathan; Liddle, Andrew R., E-mail: m.dias@sussex.ac.uk, E-mail: j.frazer@sussex.ac.uk, E-mail: a.liddle@sussex.ac.uk [Astronomy Centre, University of Sussex, Brighton BN1 9QH (United Kingdom)
2012-06-01
We analyse the multifield behaviour in D-brane inflation when contributions from the bulk are taken into account. For this purpose, we study a large number of realisations of the potential; we find the nature of the inflationary trajectory to be very consistent despite the complex construction. Inflation is always canonical and occurs in the vicinity of an inflection point. Extending the transport method to non-slow-roll and to calculate the running, we obtain distributions for observables. The spectral index is typically blue and the running positive, putting the model under moderate pressure from WMAP7 constraints. The local f{sub NL} and tensor-to-scalar ratio are typically unobservably small, though we find approximately 0.5% of realisations to give observably large local f{sub NL}. Approximating the potential as sum-separable, we are able to give fully analytic explanations for the trends in observed behaviour. Finally we find the model suffers from the persistence of isocurvature perturbations, which can be expected to cause further evolution of adiabatic perturbations after inflation. We argue this is a typical problem for models of multifield inflation involving inflection points and renders models of this type technically unpredictive without a description of reheating.
Multifield consequences for D-brane inflation
International Nuclear Information System (INIS)
Dias, Mafalda; Frazer, Jonathan; Liddle, Andrew R.
2012-01-01
We analyse the multifield behaviour in D-brane inflation when contributions from the bulk are taken into account. For this purpose, we study a large number of realisations of the potential; we find the nature of the inflationary trajectory to be very consistent despite the complex construction. Inflation is always canonical and occurs in the vicinity of an inflection point. Extending the transport method to non-slow-roll and to calculate the running, we obtain distributions for observables. The spectral index is typically blue and the running positive, putting the model under moderate pressure from WMAP7 constraints. The local f NL and tensor-to-scalar ratio are typically unobservably small, though we find approximately 0.5% of realisations to give observably large local f NL . Approximating the potential as sum-separable, we are able to give fully analytic explanations for the trends in observed behaviour. Finally we find the model suffers from the persistence of isocurvature perturbations, which can be expected to cause further evolution of adiabatic perturbations after inflation. We argue this is a typical problem for models of multifield inflation involving inflection points and renders models of this type technically unpredictive without a description of reheating
The bosonic mother of fermionic D-branes
Chattaraputi, Auttakit; Englert, Francois; Houart, Laurent; Taormina, Anne
2002-01-01
We extend the search for fermionic subspaces of the bosonic string compactified on E8 X SO(16) lattices to include all fermionic D-branes. This extension constraints the truncation procedure previously proposed and relates the fermionic strings, supersymmetric or not, to the global structure of the SO(16) group. The specific properties of all the fermionic D-branes are found to be encoded in its universal covering, whose maximal toroid defines the configuration space torus of their mother bos...
E{sub 6} Yukawa couplings in F-theory as D-brane instanton effects
Energy Technology Data Exchange (ETDEWEB)
Collinucci, Andrés [Physique Théorique et Mathématique and International Solvay Institutes,Université Libre de Bruxelles, C.P. 231, 1050 Bruxelles (Belgium); García-Etxebarria, Iñaki [Max Planck Institute for Physics,Föhringer Ring 6, 80805 Munich (Germany)
2017-03-29
At weak coupling the neighborhood of a E{sub 6} Yukawa point in SU(5) GUT F-theory models is described by a non-resolvable orientifold of the conifold. We explicitly show, first directly in IIB and then via a mirror symmetry argument, that in this limit the E{sub 6} Yukawa coupling is better described as coming from the non-perturbative contribution of a euclidean D1-brane wrapping the non-resolvable cycle. We also discuss how the M-theory description interpolates between the weak and strong coupling viewpoints.
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.
On the microcanonical description D-brane thermodynamics
International Nuclear Information System (INIS)
Meana, Marco Laucelli; Penalba, Jesus 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
U-duality and D-brane combinatorics
Pioline, B
1998-01-01
We investigate D-brane instanton contributions to R^4 couplings in any toroidal compactification of type II theories. Starting from the 11D supergravity one-loop four-graviton amplitude computed by Green, Gutperle and Vanhove, we derive the non-perturbative O(e^{-1/\\lambda}) corrections to R^4 couplings by a sequence of T-dualities, and interpret them as precise configurations of bound states of D-branes wrapping cycles of the compactification torus. Dp-branes explicitely appear as fluxes on D(p+2)-branes, and as gauge instantons on D(p+4)-branes. Specific rules for weighting these contributions are obtained, which should carry over to more general situations. Furthermore, it is shown that U-duality in D<=6 relates these D-brane configurations to O(e^{-1/\\lambda^2}) instantons for which a geometric interpretation is still lacking.
Euclidean D-branes and higher-dimensional gauge theory
International Nuclear Information System (INIS)
Acharya, B.S.; Figueroa-O'Farrill, J.M.; Spence, B.; O'Loughlin, M.
1997-07-01
We consider euclidean D-branes wrapping around manifolds of exceptional holonomy in dimensions seven and eight. The resulting theory on the D-brane-that is, the dimensional reduction of 10-dimensional supersymmetric Yang-Mills theory-is a cohomological field theory which describes the topology of the moduli space of instantons. The 7-dimensional theory is an N T =2 (or balanced) cohomological theory given by an action potential of Chern-Simons type. As a by-product of this method, we construct a related cohomological field theory which describes the monopole moduli space on a 7-manifold of G 2 holonomy. (author). 22 refs, 3 tabs
Probing near extremal black holes with D-branes
International Nuclear Information System (INIS)
Maldacena, J.
1998-01-01
We calculate the one loop effective action for D-brane probes moving in the presence of near Bogomol close-quote nyi-Prasad-Sommerfield D-branes. The v 2 term agrees with supergravity in all cases and the static force agrees for a five-dimensional black hole with two large charges. It also agrees qualitatively in all the other cases. We make some comments on the M(atrix) theory interpretation of these results. copyright 1998 The American Physical Society
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
q-deformed oscillators and D-branes on conifold
International Nuclear Information System (INIS)
Okuyama, Kazumi
2009-01-01
We study the q-deformed oscillator algebra acting on the wavefunctions of non-compact D-branes in the topological string on conifold. We find that the mirror B-model curve of conifold appears from the commutation relation of the q-deformed oscillators
D-brane disformal coupling and thermal dark matter
Dutta, Bhaskar; Jimenez, Esteban; Zavala, Ivonne
2017-11-01
Conformal and disformal couplings between a scalar field and matter occur naturally in general scalar-tensor theories. In D-brane models of cosmology and particle physics, these couplings originate from the D-brane action describing the dynamics of its transverse (the scalar) and longitudinal (matter) fluctuations, which are thus coupled. During the post-inflationary regime and before the onset of big bang nucleosynthesis (BBN), these couplings can modify the expansion rate felt by matter, changing the predictions for the thermal relic abundance of dark matter particles and thus the annihilation rate required to satisfy the dark matter content today. We study the D-brane-like conformal and disformal couplings effect on the expansion rate of the Universe prior to BBN and its impact on the dark matter relic abundance and annihilation rate. For a purely disformal coupling, the expansion rate is always enhanced with respect to the standard one. This gives rise to larger cross sections when compared to the standard thermal prediction for a range of dark matter masses, which will be probed by future experiments. In a D-brane-like scenario, the scale at which the expansion rate enhancement occurs depends on the string coupling and the string scale.
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.)
Reheating the D-brane universe via instant preheating
International Nuclear Information System (INIS)
Panda, Sudhakar; Sami, M.; Thongkool, I.
2010-01-01
We investigate a possibility of reheating in a scenario of D-brane inflation in a warped deformed conifold background which includes perturbative corrections to throat geometry sourced by a chiral operator of dimension 3/2 in the conformal field theory. The effective D-brane potential, in this case, belongs to the class of nonoscillatory models of inflation for which the conventional reheating mechanism does not work. We find that gravitational particle production is inefficient and leads to reheating temperature of the order of 10 8 GeV. We show that instant preheating is quite suitable to the present scenario and can easily reheat the universe to a temperature which is higher by about 3 orders of magnitude than its counterpart associated with gravitational particle production. The reheating temperature is shown to be insensitive to a particular choice of inflationary parameters suitable to observations.
Extensive numerical study of a D-brane, anti-D-brane system in AdS5/CFT4
International Nuclear Information System (INIS)
Hegedűs, Árpád
2015-01-01
In this paper the hybrid-NLIE approach of http://dx.doi.org/10.1007/JHEP08(2012)022 is extended to the ground state of a D-brane anti-D-brane system in AdS/CFT. The hybrid-NLIE equations presented in the paper are finite component alternatives of the previously proposed TBA equations and they admit an appropriate framework for the numerical investigation of the ground state of the problem. Straightforward numerical iterative methods fail to converge, thus new numerical methods are worked out to solve the equations. Our numerical data confirm the previous TBA data. In view of the numerical results the mysterious L=1 case is also commented in the paper.
Level-rank duality of untwisted and twisted D-branes
International Nuclear Information System (INIS)
Naculich, Stephen G.; Schnitzer, Howard J.
2006-01-01
Level-rank duality of untwisted and twisted D-branes of WZW models is explored. We derive the relation between D0-brane charges of level-rank dual untwisted D-branes of su-bar (N) K and sp-bar (n) k , and of level-rank dual twisted D-branes of su-bar (2n+1) 2k+1 . The analysis of level-rank duality of twisted D-branes of su-bar (2n+1) 2k+1 is facilitated by their close relation to untwisted D-branes of sp-bar (n) k . We also demonstrate level-rank duality of the spectrum of an open string stretched between untwisted or twisted D-branes in each of these cases
Coset models and D-branes in group manifolds
International Nuclear Information System (INIS)
Orlando, Domenico
2006-01-01
We conjecture the existence of a duality between heterotic closed strings on homogeneous spaces and symmetry-preserving D-branes on group manifolds, based on the observation about the coincidence of the low-energy field description for the two theories. For the closed string side we also give an explicit proof of a no-renormalization theorem as a consequence of a hidden symmetry and infer that the same property should hold true for the higher order terms of the dbi action
Phenomenological analysis of D-brane Pati-Salam vacua
Anastasopoulos, P.; Vlachos, N.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...
On orientifolds of c=1 orbifolds
Energy Technology Data Exchange (ETDEWEB)
Dijkstra, T.P.T. [NIKHEF, PO Box 41882, 1009 DB Amsterdam (Netherlands); Gato-Rivera, B. [NIKHEF, PO Box 41882, 1009 DB Amsterdam (Netherlands); Riccioni, F. [NIKHEF, PO Box 41882, 1009 DB Amsterdam (Netherlands)]. E-mail: f.riccioni@damtp.cam.ac.uk; Schellekens, A.N. [NIKHEF, PO Box 41882, 1009 DB Amsterdam (Netherlands)
2004-10-25
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.
Supergravity solutions for D-branes in Hpp-wave backgrounds
International Nuclear Information System (INIS)
Bain, P.; Meessen, P.; Zamaklar, M.
2002-05-01
We derive two families of supergravity solutions describing D-branes in the maximally supersymmetric Hpp-wave background. The first family of solutions corresponds to quarter-BPS D-branes. These solutions are delocalised along certain directions transverse to the pp-wave The second family corresponds to the non-supersymmetric D-branes. These solutions are fully localised. A peculiar feature of the nonsupersymmetric solutions is that gravity becomes repulsive close to the core of the D-brane. Both families preserve the amount of supersymmetry predicted by the D-brane probe/CFT analysis. All solutions are written in Brinkman coordinates. To construct these kind of solutions it is crucial to identify the coordinates in which the ansatz looks the simplest. We argue that the natural coordinates to get the supergravity description of the half-BPS branes are the Rosen coordinates. (author)
A Delicate Universe: Compactification Obstacles to D-brane Inflation
International Nuclear Information System (INIS)
Baumann, Daniel; Dymarsky, Anatoly; McAllister, Liam; Klebanov, Igor R.; Steinhardt, Paul J.
2007-01-01
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, z 1 =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
On D-branes from gauged linear sigma models
International Nuclear Information System (INIS)
Govindarajan, S.; Jayaraman, T.; Sarkar, T.
2001-01-01
We study both A-type and B-type D-branes in the gauged linear sigma model by considering worldsheets with boundary. The boundary conditions on the matter and vector multiplet fields are first considered in the large-volume phase/non-linear sigma model limit of the corresponding Calabi-Yau manifold, where we find that we need to add a contact term on the boundary. These considerations enable to us to derive the boundary conditions in the full gauged linear sigma model, including the addition of the appropriate boundary contact terms, such that these boundary conditions have the correct non-linear sigma model limit. Most of the analysis is for the case of Calabi-Yau manifolds with one Kaehler modulus (including those corresponding to hypersurfaces in weighted projective space), though we comment on possible generalisations
Heterotic/type I duality and D-brane instantons
Bachas, C.; Fabre, C.; Kiritsis, E.; Obers, N. A.; Vanhove, P.
1998-01-01
We study heterotic/type I duality in d = 8, 9 uncompactified dimensions. We consider the special ("BPS-saturated") F4 and R4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be motivated as arising from a D-brane instanton calculation on the type I side.
Heterotic/type I duality and D-brane instantons
International Nuclear Information System (INIS)
Bachas, C.; Fabre, C.; Vanhove, P.
1998-01-01
We study heterotic/type I duality in d=8,9 uncompactified dimensions. We consider the special (''BPS-saturated'') F 4 and R 4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be motivated as arising from a D-brane instanton calculation on the type I side. (orig.)
Heterotic / type-I duality and D-brane instantons
Bachas, C P; Kiritsis, Elias B; Obers, N A; Vanhove, P
1998-01-01
We study heterotic/type-I duality in d=8,9 uncompactified dimensions. We consider the special (``BPS saturated'') F^4 and R^4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be recognized easily as arising from a D-brane instanton calculation on the type-I side.
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...
Gaugings at angles from orientifold reductions
International Nuclear Information System (INIS)
Roest, Diederik
2009-01-01
We consider orientifold reductions to N= 4 gauged supergravity in four dimensions. A special feature of this theory is that different factors of the gauge group can have relative angles with respect to the electro-magnetic SL(2) symmetry. These are crucial for moduli stabilization and de Sitter vacua. We show how such gaugings at angles generically arise in orientifold reductions.
Supersymmetric composite models on intersecting D-branes
International Nuclear Information System (INIS)
Kitazawa, Noriaki
2004-01-01
We construct supersymmetric composite models of quarks and leptons from type IIA T6/(Z2xZ2) orientifold with intersecting D6-branes. In case of T6=T2xT2xT2 with no tilted T2, a composite model of supersymmetric SU(5) grand unified theory with four generations is constructed. In case of that one T2 is tilted, a composite model with SU(3)cxSU(2)LxU(1)Y gauge symmetry with three generations of left-handed quarks and leptons is constructed. These models are not realistic, but contain relatively fewer additional exotic particles and U(1) gauge symmetries due to the introduction of the compositeness of quarks and leptons. The masses of some exotic particles are naturally generated through the Yukawa interactions among 'preons'
D-brane anti-brane annihilation in an expanding universe
International Nuclear Information System (INIS)
Majumdar, Mahbub; Davis, Anne-Christine
2003-01-01
The time-varying density of D-branes and anti-D-branes in an expanding universe is calculated. The D-brane anti-brane annihilation rate is shown to be too small to compete with the expansion rate of a FRW type universe and the branes over-close the universe. This brane problem is analogous to the old monopole problem. Interestingly however, it is shown that small dimension D-branes annihilate more slowly than high dimension branes. Hence, an initially brany universe may be filled with only low dimension branes at late times. When combined with an appropriate late inflationary theory this leads to an attractive dynamical way to create a realistic braneworld scenario. (author)
Metamaterials mimicking dynamic spacetime, D-brane and noncommutativity in string theory
International Nuclear Information System (INIS)
Miao Rongxin; Zheng Rui; Li Miao
2011-01-01
We propose a scheme to mimic the expanding cosmos in 1+2 dimensions in laboratory. Furthermore, we develop a general procedure to use nonlinear metamaterials to mimic D-brane and noncommutativity in string theory.
Monopoles and instantons on partially compactified D-branes
International Nuclear Information System (INIS)
Lee, K.; Yi, P.
1997-01-01
Motivated by the recent D-brane constructions of world-volume monopoles and instantons, we study the supersymmetric SU(N) Yang-Mills theory on S 1 xR 3+1 , spontaneously broken by a Wilson loop. In addition to the usual N-1 fundamental monopoles, the Nth Bogomol close-quote nyi-Prasad-Sommerfield monopole appears from the Kaluza-Klein sector. When all N monopoles are present, net magnetic charge vanishes and the solution can be reinterpreted as a Wilson-loop instanton of unit Pontryagin number. The instanton-multimonopole moduli space is explicitly constructed, and seen to be identical to a Coulomb phase moduli space of a U(1) N gauge theory in 2+1 dimensions related to Kronheimer close-quote s gauge theory of SU(N)-type. This extends the results by Intriligator and Seiberg to the finite couplings that, in the infrared limit of Kronheimer close-quote s theory, the Coulomb phase parametrizes a centered SU(N) instanton. We also elaborate on the case of restored SU(N) symmetry. copyright 1997 The American Physical Society
String creation, D-branes and effective field theory
International Nuclear Information System (INIS)
Hung Lingyan
2008-01-01
This paper addresses several unsettled issues associated with string creation in systems of orthogonal Dp-D(8-p) branes. The interaction between the branes can be understood either from the closed string or open string picture. In the closed string picture it has been noted that the DBI action fails to capture an extra RR exchange between the branes. We demonstrate how this problem persists upon lifting to M-theory. These D-brane systems are analysed in the closed string picture by using gauge-fixed boundary states in a non-standard lightcone gauge, in which RR exchange can be analysed precisely. The missing piece in the DBI action also manifests itself in the open string picture as a mismatch between the Coleman-Weinberg potential obtained from the effective field theory and the corresponding open string calculation. We show that this difference can be reconciled by taking into account the superghosts in the (0+1) effective theory of the chiral fermion, that arises from gauge fixing the spontaneously broken world-line local supersymmetries
Prospects of inflation in delicate D-brane cosmology
International Nuclear Information System (INIS)
Panda, Sudhakar; Sami, M.; Tsujikawa, Shinji
2007-01-01
We study D-brane inflation in a warped conifold background that includes brane-position dependent corrections for the nonperturbative superpotential. Instead of stabilizing the volume modulus χ at instantaneous minima of the potential and studying the inflation dynamics with an effective single field (radial distance between a brane and an antibrane) φ, we investigate the multifield inflation scenario involving these two fields. The two-field dynamics with the potential V(φ,χ) in this model is significantly different from the effective single-field description in terms of the field φ when the field χ is integrated out. The latter picture underestimates the total number of e-foldings even by 1 order of magnitude. We show that a correct single-field description is provided by a field ψ obtained from a rotation in the two-field space along the background trajectory. This model can give a large number of e-foldings required to solve flatness and horizon problems at the expense of fine-tunings of model parameters. We also estimate the spectra of density perturbations and show that the slow-roll parameter η ψψ =M pl 2 V ,ψψ /V in terms of the rotated field ψ determines the spectral index of scalar metric perturbations. We find that it is generally difficult to satisfy, simultaneously, both constraints of the spectral index and the cosmic background explorer normalization, while the tensor to scalar ratio is sufficiently small to match with observations
D-brane probes in the matrix model
International Nuclear Information System (INIS)
Ferrari, Frank
2014-01-01
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 ξ-gauge to compute the brane action. The action depends on ξ in a very non-trivial way, yet we show explicitly that its critical value does not and coincides with twice the free energy, as required by general consistency. This is made possible by a phenomenon of ghost condensation and the spontaneous breaking of the equivariant BRST symmetry
Poisson-Lie T-duality open strings and D-branes
Klimcik, C.
1996-01-01
Global issues of the Poisson-Lie T-duality are addressed. It is shown that oriented open strings propagating on a group manifold G are dual to D-brane - anti-D-brane pairs propagating on the dual group manifold \\ti G. The D-branes coincide with the symplectic leaves of the standard Poisson structure induced on the dual group \\ti G by the dressing action of the group G. T-duality maps the momentum of the open string into the mutual distance of the D-branes in the pair. The whole picture is then extended to the full modular space M(D) of the Poisson-Lie equivalent \\si-models which is the space of all Manin triples of a given Drinfeld double.T-duality rotates the zero modes of pairs of D-branes living on targets belonging to M(D). In this more general case the D-branes are preimages of symplectic leaves in certain Poisson homogeneous spaces of their targets and, as such, they are either all even or all odd dimensional.
D-branes in a big bang/big crunch universe: Nappi-Witten gauged WZW model
Energy Technology Data Exchange (ETDEWEB)
Hikida, Yasuaki [School of Physics and BK-21 Physics Division, Seoul National University, Seoul 151-747 (Korea, Republic of); Nayak, Rashmi R. [Dipartimento di Fisica and INFN, Sezione di Roma 2, ' Tor Vergata' ' , Rome 00133 (Italy); Panigrahi, Kamal L. [Dipartimento di Fisica and INFN, Sezione di Roma 2, ' Tor Vergata' , Rome 00133 (Italy)
2005-05-01
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.
U duality, D-branes, and black hole emission rates: Agreements and disagreements
International Nuclear Information System (INIS)
Dowker, F.; Kastor, D.; Traschen, J.
1998-01-01
An expression for the spacetime absorption coefficient of a scalar field in a five-dimensional, near-extremal black hole background is derived, which has the same form as that presented by Maldacena and Strominger, but is valid over a larger, U-duality invariant region of parameter space and in general disagrees with the corresponding D-brane result. We develop an argument, based on D-brane thermodynamics, which specifies the range of parameters over which agreement should be expected. For neutral emission, the spacetime and D-brane results agree over this range. However, for charged emission, we find disagreement in the 'fat black hole' regime, in which charge is quantized in smaller units on the brane than in the bulk of spacetime. We indicate a possible problem with the D-brane model in this regime. We also use the Born approximation to study the high frequency limit of the absorption coefficient and find that it approaches unity, for large black hole backgrounds, at frequencies still below the string scale, again in disagreement with D-brane results. copyright 1998 The American Physical Society
Extensive numerical study of a D-brane, anti-D-brane system in AdS{sub 5}/CFT{sub 4}
Energy Technology Data Exchange (ETDEWEB)
Hegedűs, Árpád [MTA Lendület Holographic QFT Group, Wigner Research Centre,H-1525 Budapest 114, P.O.B. 49 (Hungary)
2015-04-20
In this paper the hybrid-NLIE approach of http://dx.doi.org/10.1007/JHEP08(2012)022 is extended to the ground state of a D-brane anti-D-brane system in AdS/CFT. The hybrid-NLIE equations presented in the paper are finite component alternatives of the previously proposed TBA equations and they admit an appropriate framework for the numerical investigation of the ground state of the problem. Straightforward numerical iterative methods fail to converge, thus new numerical methods are worked out to solve the equations. Our numerical data confirm the previous TBA data. In view of the numerical results the mysterious L=1 case is also commented in the paper.
Mirror symmetry, D-brane superpotentials and Ooguri-Vafa invariants of Calabi-Yau manifolds
Zhang, Shan-Shan; Yang, Fu-Zhong
2015-12-01
The D-brane superpotential is very important in the low energy effective theory. As the generating function of all disk instantons from the worldsheet point of view, it plays a crucial role in deriving some important properties of the compact Calabi-Yau manifolds. By using the generalized GKZ hypergeometric system, we will calculate the D-brane superpotentials of two non-Fermat type compact Calabi-Yau hypersurfaces in toric varieties, respectively. Then according to the mirror symmetry, we obtain the A-model superpotentials and the Ooguri-Vafa invariants for the mirror Calabi-Yau manifolds. Supported by Y4JT01VJ01 and NSFC(11475178)
Remarks on global anomalies in RCFT orientifolds
Energy Technology Data Exchange (ETDEWEB)
Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Matematicas y Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands) and Instituto de Matematicas y Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain) and IMAPP, Radboud Universiteit, Nijmegen (Netherlands)]. E-mail: t58@nikhef.nl
2006-01-26
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.
Gaugings at angles from orientifold reductions
Roest, D.
2009-01-01
We consider orientifold reductions to N = 4 gauged supergravity in four dimensions. A special feature of this theory is that different factors of the gauge group can have relative angles with respect to the electro-magnetic SL(2) symmetry. These are crucial for moduli stabilization and de Sitter
Gravitational Couplings for Generalized Orientifold Planes
Giraldo, Juan Fernando Ospina
2000-01-01
The Wess-Zumino action for generalized orientifold planes (GOp-planes) is presented and a series power expantion is realized from which processes that involves GOp-planes, RR-forms, gravitons and gaugeons, are obtained. Finally non-standard GOp-planes are showed.
D-brane description of new open string solutions in AdS5
International Nuclear Information System (INIS)
Kluson, J.
2008-01-01
In this Letter we find D-brane descriptions of some of new open string solutions that were found in (0804.3438 [hep-th]). These D5-brane and D3-brane configurations give gravitational dual descriptions of Wilson loops in some particular representations
Rolling down the throat in NS5-brane background: the case of electrified D-brane
International Nuclear Information System (INIS)
Nakayama, Yu; Takayanagi, Hiromitsu; Panigrahi, Kamal L.; Rey, Soo-Jong
2005-01-01
We study rolling radion dynamics of electrified D-brane in NS5-brane background, both in effective field theory and in full open string theory. We construct exact boundary states and, from them, extract conserved Noether currents. We argue that T-duality and Lorentz boost offer an intuitive approach. In the limit of large number of NS5-branes, both boundary wave functions and conserved currents are sharply peaked and agree with those deduced from the effective field theory. As the number of NS5-branes is reduced, width around the peak becomes wider by string corrections. We also study radiative decay process. By applying Lorentz covariance, we show how the decay of electrified D-brane is related to that of bare D-brane. We compute spectral moments of final state energy and winding quantum number. Using Lorentz covariance argument, we explain in elementary way why winding quantum number should be included and derive rules how to do so. We conclude that Kutasov's 'geometric realization' between radion rolling dynamics and tachyon rolling dynamics holds universally, both for bare and electrified D-branes. (author)
Witten Effect and Fractional Charges on the Domain Wall and the D-Brane-Like Dot
Kanazawa, I.; Maeda, R.
2018-04-01
We have discussed the anomalous excitations such as dyons, Majorana fermions, and quark-like fermions on the domain wall in topological materials and the D-brane-like dot, and the relation to low-energy hadrons in QCD, from the viewpoint of a field-theoretical formula.
Orientifolding of the ABJ Fermi gas
International Nuclear Information System (INIS)
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 N=5O(n)×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 http://arxiv.org/abs/1410.7658.
Orientifolding of the ABJ Fermi gas
Okuyama, Kazumi
2016-03-01
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 {N}=5O(n)× 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.
New WZW D-branes from the algebra of Wilson loop operators
International Nuclear Information System (INIS)
Monnier, Samuel
2009-01-01
We investigate the algebra generated by the topological Wilson loop operators in WZW models. Wilson loops describe the nontrivial fixed points of the boundary renormalization group flows triggered by Kondo perturbations. Their enveloping algebra therefore encodes all the fixed points which can be reached by sequences of Kondo flows. This algebra is easily described in the case of SU(2), but displays a very rich structure for higher rank groups. In the latter case, its action on known D-branes creates a profusion of new and generically non-rational D-branes. We describe their symmetries and the geometry of their worldvolumes. We briefly explain how to extend these results to coset models.
D-branes in N=2 Liouville theory and its mirror
International Nuclear Information System (INIS)
Israel, Dan; Pakman, Ari; Troost, Jan
2005-01-01
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 H 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
On the 3-form formulation of axion potentials from D-brane instantons
Energy Technology Data Exchange (ETDEWEB)
García-Valdecasas, Eduardo [Instituto de Física Teórica UAM-CSIC,C/Nicolás Cabrera 13-15, Campus de Cantoblanco, 28049 Madrid (Spain); Departamento de Física Teórica, Universidad Autónoma de Madrid,Campus de Cantoblanco, 28049 Madrid (Spain); Uranga, Angel [Instituto de Física Teórica UAM-CSIC,C/Nicolás Cabrera 13-15, Campus de Cantoblanco, 28049 Madrid (Spain)
2017-02-16
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.
Global D-brane models with stabilised moduli and light axions
Cicoli, Michele
2014-03-01
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.
Comparing D-branes and black holes with 0- and 6-brane charges
International Nuclear Information System (INIS)
Pierre, J.M.
1997-01-01
We consider configurations of D6-branes with a D0-brane charge given by recent work of Taylor and compute interaction potentials with various D-brane probes using a 1-loop open string calculation. These results are compared to a supergravity calculation using the solution given by Sheinblatt of an extremal black hole carrying 0-brane and 6-brane charges. copyright 1997 The American Physical Society
High energy effects on D-brane and black hole emission rates
International Nuclear Information System (INIS)
Das, S.; Dasgupta, A.; Sarkar, T.
1997-01-01
We study the emission of scalar particles from a class of near-extremal five-dimensional black holes and the corresponding D-brane configuration at high energies. We show that the distribution functions and the black hole greybody factors are modified in the high energy tail of the Hawking spectrum in such a way that the emission rates exactly match. We extend the results to charged scalar emission and to four dimensions. copyright 1997 The American Physical Society
D-brane superpotentials and Ooguri-Vafa invariants of compact Calabi-Yau threefolds
Xu, Feng-Jun; Yang, Fu-Zhong
2015-04-01
We calculate the D-brane superpotentials for two compact Calabi-Yau manifolds X14(1,1,2,3,7) and X8(1,1,1,2,3) which are of non-Fermat type in the type II string theory. By constructing the open mirror symmetry, we also compute the Ooguri-Vafa invariants, which are related to the open Gromov-Witten invariants. Supported by NSFC (11075204, 11475178)
Nonthreshold D-brane bound states and black holes with nonzero entropy
International Nuclear Information System (INIS)
Costa, M.S.; Cvetic, M.
1997-01-01
We start with Bogomol close-quote nyi-Prasad-Sommerfield- (BPS) saturated configurations of two (orthogonally) intersecting M-branes and use the electromagnetic duality or dimensional reduction along a boost, in order to obtain new p-brane bound states. In the first case the resulting configurations are interpreted as BPS-saturated nonthreshold bound states of intersecting p-branes, and in the second case as p-branes intersecting at angles and their duals. As a by-product we deduce the enhancement of supersymmetry as the angle approaches zero. We also comment on the D-brane theory describing these new bound states, and a connection between the angle and the world-volume gauge fields of the D-brane system. We use these configurations to find new embeddings of the four- and five-dimensional black holes with nonzero entropy, whose entropy now also depends on the angle and world-volume gauge fields. The corresponding D-brane configuration sheds light on the microscopic entropy of such black holes. copyright 1997 The American Physical Society
Gauge threshold corrections for local orientifolds
International Nuclear Information System (INIS)
Conlon, Joseph P.; Palti, Eran
2009-01-01
We study gauge threshold corrections for systems of fractional branes at local orientifold singularities and compare with the general Kaplunovsky-Louis expression for locally supersymmetric N = 1 gauge theories. We focus on branes at orientifolds of the C 3 /Z 4 , C 3 /Z 6 and C 3 /Z 6 ' singularities. We provide a CFT construction of these theories and compute the threshold corrections. Gauge coupling running undergoes two phases: one phase running from the bulk winding scale to the string scale, and a second phase running from the string scale to the infrared. The first phase is associated to the contribution of N = 2 sectors to the IR β functions and the second phase to the contribution of both N = 1 and N = 2 sectors. In contrast, naive application of the Kaplunovsky-Louis formula gives single running from the bulk winding mode scale. The discrepancy is resolved through 1-loop non-universality of the holomorphic gauge couplings at the singularity, induced by a 1-loop redefinition of the twisted blow-up moduli which couple differently to different gauge nodes. We also study the physics of anomalous and non-anomalous U(1)s and give a CFT description of how masses for non-anomalous U(1)s depend on the global properties of cycles.
Aspects of stability and phenomenology in type IIA orientifolds with intersecting D6-branes
International Nuclear Information System (INIS)
Ott, T.
2004-01-01
Intersecting branes have been the subject of an elaborate string model building for several years. After a general introduction into string theory, this work introduces in detail the toroidal and Z N -orientifolds. The picture involving D9-branes with B-fluxes is shortly reviewed, but the main discussion employs the T-dual picture of intersecting D6-branes. The derivation of the R-R and NS-NS tadpole cancellation conditions in the conformal field theory is shown in great detail. Various aspects of the open and closed chiral and non-chiral massless spectrum are discussed, involving spacetime anomalies and the generalized Green-Schwarz mechanism. An introduction into possible gauge breaking mechanisms is given, too. Afterwards, both N=1 supersymmetric and non-supersymmetric approaches to low energy model building are treated. Firstly, the problem of complex structure instabilities in toroidal ΩR-orientifolds is approached by a Z 3 -orbifolded model. In particular, a stable non-supersymmetric standard-like model with three fermion generations is discussed. This model features the standard model gauge groups at the same time as having a massless hypercharge, but possessing an additional global B-L symmetry. The electroweak Higgs mechanism and the Yukawa couplings are not realized in the usual way. It is shown that this model descends naturally from a flipped SU(5) GUT model, where the string scale has to be at least of the order of the GUT scale. Secondly, supersymmetric models on the Z 4 -orbifold are discussed, involving exceptional 3-cycles and the explicit construction of fractional D-branes. A three generation Pati-Salam model is constructed as a particular example, where several brane recombination mechanisms are used, yielding non-flat and non-factorizable branes. This model even can be broken down to a MSSM-like model with a massless hypercharge. Finally, the possibility that unstable closed and open string moduli could have played the role of the inflaton in
Closed string emission from unstable D-brane with background electric field
International Nuclear Information System (INIS)
Nagami, Kenji
2004-01-01
We study the closed string emission from an unstable Dp-brane with constant background electric field in bosonic string theory. The average total number density and the average total energy density of emitted closed strings are explicitly calculated in the presence of electric field. It is explicitly shown that the energy density in the UV region becomes finite whenever the background electric field is switched on. The energy density converted into closed strings in the presence of electric field is negligibly small compared with the D-brane tension in the weak string coupling limit. (author)
The energy-carrying velocity and rolling of tachyons of unstable D-branes
International Nuclear Information System (INIS)
Chung, Jin Hyun; L'Yi, Won Sik
2004-01-01
We show that the tachyons that originate from unstable D-branes carry energy and momentum at a velocity β = c 2 /v; where v is the phase velocity, which is greater than c. For an observer who moves with velocity β, the tachyon is observed to be moving from one of the ground states of the tachyon potential to a potential hill. The tachyon is found to either pass over the hill or bounce back to the original ground state. Another possible solution is the case that is margial to these; that is, the tachyon reaches the top of the potential hill and stays there forever.
Space-time uncertainty and approaches to D-brane field theory
International Nuclear Information System (INIS)
Yoneya, Tamiaki
2008-01-01
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, the 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. (author)
Inflation driven by single geometric tachyon with D-brane orbiting around NS5-branes
International Nuclear Information System (INIS)
Kwon, Pyung Seong; Jun, Gyeong Yun; Panigrahi, Kamal L.; Sami, M.
2012-01-01
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.
D-branes in non-critical superstrings and duality in N = 1 gauge theories with flavor
International Nuclear Information System (INIS)
Murthy, S.; Troost, J.
2006-06-01
We study D-branes in the superstring background R 3,1 x SL(2, R) k =1/U(1) which are extended in the cigar direction. Some of these branes are new. The branes realize flavor in the four dimensional N = 1 gauge theories on the D-branes localized at the tip of the cigar. We study the analytic properties of the boundary conformal field theories on these branes with respect to their defining parameter and find non- trivial monodromies in this parameter. Through this approach, we gain a better understanding of the brane set-ups in ten dimensions involving wrapped NS5-branes. As one application, using the boundary conformal field theory description of the electric and magnetic D-branes, we can understand electric-magnetic (Seiberg) duality in N = 1 SQCD microscopically in a string theoretic context. (author)
DDF construction and D-brane boundary states in pure spinor formalism
International Nuclear Information System (INIS)
Mukhopadhyay, Partha
2006-01-01
Open string boundary conditions for non-BPS D-branes in type II string theories discussed in hep-th/0505157 give rise to two sectors with integer (R sector) and half-integer (NS sector) modes for the combined fermionic matter and bosonic ghost variables in pure spinor formalism. Exploiting the manifest supersymmetry of the formalism we explicitly construct the DDF (Del Giudice, Di Vecchia, Fubini) states in both the sectors which are in one-to-one correspondence with the states in light-cone Green-Schwarz formalism. We also give a proof of validity of this construction. A similar construction in the closed string sector enables us to define a physical Hilbert space in pure spinor formalism which is used to project the covariant boundary states of both the BPS and non-BPS instantonic D-branes. These projected boundary states take exactly the same form as those found in light-cone Green-Schwarz formalism and are suitable for computing the cylinder diagram with manifest open-closed duality
D-branes in a non-critical superstrings and minimal super Yang-Mills in various dimensions
International Nuclear Information System (INIS)
Ashok, S.K.; Murthy, S.; Troost, J.
2005-11-01
We construct and analyze D-branes in superstring theories in even dimensions less than ten. The backgrounds under study are supersymmetric R d-1,1 x SL(2,R) k /U(1) where the level of the supercoset is tuned such as to provide bona fide string theory backgrounds. We provide exact boundary states for D-branes that are localized at the tip of the cigar SL(2,R)/U(1) supercoset conformal field theory. We analyze the spectra of open strings on these D-branes and show explicitly that they are consistent with supersymmetry in d = 2,4 and 6. The low energy theory on the world-volume of the D-brane in each case is pure Yang-Mills theory with minimal supersymmetry. In the case with four macroscopic flat directions d = 4, we realize an N = 1 super Yang-Mills theory, and we interpret the backreaction for the dilaton as the running of the gauge coupling, and study the relation between R-symmetry breaking in the gauge theory and the backreaction on the Rr axion. (author)
D-branes at toric singularities: model building, Yukawa couplings and flavour physics
International Nuclear Information System (INIS)
Krippendorf, Sven; Dolan, Matthew J.; Maharana, Anshuman; Quevedo, Fernando
2010-02-01
We discuss general properties of D-brane model building at toric singularities. Using dimer techniques to obtain the gauge theory from the structure of the singularity, we extract results on the matter sector and superpotential of the corresponding gauge theory. We show that the number of families in toric phases is always less than or equal to three, with a unique exception being the zeroth Hirzebruch surface. With the physical input of three generations we find that the lightest family of quarks is massless and the masses of the other two can be hierarchically separated. We compute the CKM matrix for explicit models in this setting and find the singularities possess sufficient structure to allow for realistic mixing between generations and CP violation. (author)
Boundary conformal field theory and the worldsheet approach to D-branes
Recknagel, Andreas
2013-01-01
Boundary conformal field theory is concerned with a class of two-dimensional quantum field theories which display a rich mathematical structure and have many applications ranging from string theory to condensed matter physics. In particular, the framework allows discussion of strings and branes directly at the quantum level. Written by internationally renowned experts, this comprehensive introduction to boundary conformal field theory reaches from theoretical foundations to recent developments, with an emphasis on the algebraic treatment of string backgrounds. Topics covered include basic concepts in conformal field theory with and without boundaries, the mathematical description of strings and D-branes, and the geometry of strongly curved spacetime. The book offers insights into string geometry that go beyond classical notions. Describing the theory from basic concepts, and providing numerous worked examples from conformal field theory and string theory, this reference is of interest to graduate students and...
Non-linear Yang-Mills instantons from strings are π-stable D-branes
International Nuclear Information System (INIS)
Enger, H.; Luetken, C.A.
2004-01-01
We show that B-type Π-stable D-branes do not in general reduce to the (Gieseker-) stable holomorphic vector bundles used in mathematics to construct moduli spaces. We show that solutions of the almost Hermitian Yang-Mills equations for the non-linear deformations of Yang-Mills instantons that appear in the low-energy geometric limit of strings exist iff they are π-stable, a geometric large volume version of Π-stability. This shows that π-stability is the correct physical stability concept. We speculate that this string-canonical choice of stable objects, which is encoded in and derived from the central charge of the string-algebra, should find applications to algebraic geometry where there is no canonical choice of stable geometrical objects
D-brane potentials from multi-trace deformations in AdS/CFT
International Nuclear Information System (INIS)
Bernamonti, Alice; Craps, Ben
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 similar to geometric transition.
Instanton counting, Macdonald function and the moduli space of D-branes
International Nuclear Information System (INIS)
Awata, Hidetoshi; Kanno, Hiroaki
2005-01-01
We argue the connection of Nekrasov's partition function in the Ω background and the moduli space of D-branes, suggested by the idea of geometric engineering and Gopakumar-Vafa invariants. In the instanton expansion of N = 2 SU(2) Yang-Mills theory the Nakrasov's partition function with equivariant parameters ε 1 ,ε 2 of toric action on C 2 factorizes correctly as the character of SU(2) L x SU(2) R spin representation. We show that up to two instantons the spin contents are consistent with the Lefschetz action on the moduli space of D2-branes on (local) F 0 . We also present an attempt at constructing a refined topological vertex in terms of the Macdonald function. The refined topological vertex with two parameters of T 2 action allows us to obtain the generating functions of equivariant χ y and elliptic genera of the Hilbert scheme of n points on C 2 by the method of topological vertex
Constraints on effective Lagrangian of D-branes from non-commutative gauge theory
International Nuclear Information System (INIS)
Okawa, Yuji; Terashima, Seiji
2000-01-01
It was argued that there are two different descriptions of the effective Lagrangian of gauge fields on D-branes by non-commutative gauge theory and by ordinary gauge theory in the presence of a constant B field background. In the case of bosonic string theory, however, it was found in the previous works that the two descriptions are incompatible under the field redefinition which relates the non-commutative gauge field to the ordinary one found by Seiberg and Witten. In this paper we resolve this puzzle to observe the necessity of gauge-invariant but B-dependent correction terms involving metric in the field redefinition which have not been considered before. With the problem resolved, we establish a systematic method under the α' expansion to derive the constraints on the effective Lagrangian imposed by the compatibility of the two descriptions where the form of the field redefinition is not assumed
D-branes in a big bang/big crunch universe: Misner space
International Nuclear Information System (INIS)
Hikida, Yasuaki; Nayak, Rashmi R.; Panigrahi, Kamal L.
2005-01-01
We study D-branes in a two-dimensional lorentzian orbifold R 1,1 /Γ with a discrete boost Γ. This space is known as Misner or Milne space, and includes big crunch/big bang singularity. In this space, there are D0-branes in spiral orbits and D1-branes with or without flux on them. In particular, we observe imaginary parts of partition functions, and interpret them as the rates of open string pair creation for D0-branes and emission of winding closed strings for D1-branes. These phenomena occur due to the time-dependence of the background. Open string 2→2 scattering amplitude on a D1-brane is also computed and found to be less singular than closed string case
D-branes in a big bang/big crunch universe: Misner space
Energy Technology Data Exchange (ETDEWEB)
Hikida, Yasuaki [Theory Group, High Energy Accelerator Research Organization (KEK), Tukuba, Ibaraki 305-0801 (Japan); Nayak, Rashmi R. [Dipartimento di Fisica and INFN, Sezione di Roma 2, ' Tor Vergata' , Rome 00133 (Italy); Panigrahi, Kamal L. [Dipartimento di Fisica and INFN, Sezione di Roma 2, ' Tor Vergata' , Rome 00133 (Italy)
2005-09-01
We study D-branes in a two-dimensional lorentzian orbifold R{sup 1,1}/{gamma} with a discrete boost {gamma}. This space is known as Misner or Milne space, and includes big crunch/big bang singularity. In this space, there are D0-branes in spiral orbits and D1-branes with or without flux on them. In particular, we observe imaginary parts of partition functions, and interpret them as the rates of open string pair creation for D0-branes and emission of winding closed strings for D1-branes. These phenomena occur due to the time-dependence of the background. Open string 2{yields}2 scattering amplitude on a D1-brane is also computed and found to be less singular than closed string case.
Mirror symmetry in three-dimensional gauge theories, quivers and D-branes
International Nuclear Information System (INIS)
De Boer, J.; Ernest Orlando Lawrence Berkeley Nat. Lab., CA; Hori, K.; Ernest Orlando Lawrence Berkeley Nat. Lab., CA; Ooguri, H.; Ernest Orlando Lawrence Berkeley Nat. Lab., CA; Oz, Y.; Ernest Orlando Lawrence Berkeley Nat. Lab., CA
1997-01-01
We construct and analyze dual N=4 supersymmetric gauge theories in three dimensions with unitary and symplectic gauge groups. The gauge groups and the field content of the theories are encoded in quiver diagrams. The duality exchanges the Coulomb and Higgs branches and the Fayet-Iliopoulos and mass parameters. We analyze the classical and the quantum moduli spaces of the theories and construct an explicit mirror map between the mass parameters and the Fayet-Iliopoulos parameters of the dual. The results generalize the relation between ALE spaces and moduli spaces of SU(n) and SO(2n) instantons. We interpret some of these results from the string theory viewpoint, for SU(n) by analyzing T-duality and extremal transitions in type II string compactifications, for SO(2n) by using D-branes as probes. Finally, we make a proposal for the moduli space of vacua of these theories in the absence of matter. (orig.)
Non-supersymmetric orientifolds of Gepner models
Energy Technology Data Exchange (ETDEWEB)
Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); IMAPP, Radboud Universiteit, Nijmegen (Netherlands)], E-mail: t58@nikhef.nl
2009-01-12
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 non-supersymmetric spectra, but a large fraction of them are nevertheless partly or fully supersymmetric at the massless level.
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...
String loop moduli stabilisation and cosmology in IIB flux compactifications
International Nuclear Information System (INIS)
Cicoli, M.
2010-01-01
We present a detailed review of the moduli stabilisation mechanism and possible cosmological implications of the LARGE Volume Scenario (LVS) that emerges naturally in the context of type IIB Calabi-Yau flux compactifications. After a quick overview of physics beyond the Standard Model, we present string theory as the most promising candidate for a consistent theory of quantum gravity. We then give a pedagogical introduction to type IIB compactifications on Calabi-Yau orientifolds where most of the moduli are stabilised by turning on background fluxes. However in order to fix the Kaehler moduli one needs to consider several corrections beyond the leading order approximations. After presenting a survey of all the existing solutions to this problem, we derive the topological conditions on an arbitrary Calabi-Yau to obtain the LVS since it requires no fine-tuning of the fluxes and provides a natural solution of the hierarchy problem. After performing a systematic study of the behaviour of string loop corrections for general type IIB compactifications, we show how they play a crucial role to achieve full Kaehler moduli stabilisation in the LVS. Before examining the possible cosmological implication of these scenarios, we present a broad overview of string cosmology. We then notice how, in the case of K3-fibrations, string loop corrections give rise naturally to an inflationary model which yields observable gravity waves. We finally study the finite-temperature behaviour of the LVS and discuss prospects for future work. (Abstract Copyright [2010], Wiley Periodicals, Inc.)
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.
International Nuclear Information System (INIS)
Sevrin, Alexander; Staessens, Wieland; Wijns, Alexander
2008-01-01
We investigate N = (2, 2) supersymmetric nonlinear σ-models in the presence of a boundary. We restrict our attention to the case where the bulk geometry is described by chiral and twisted chiral superfields corresponding to a bihermitian bulk geometry with two commuting complex structures. The D-brane configurations preserving an N = 2 worldsheet supersymmetry are identified. Duality transformations interchanging chiral for twisted chiral fields and vice versa while preserving all supersymmetries are explicitly constructed. We illustrate our results with various explicit examples such as the WZW-model on the Hopf surface S 3 x S 1 . The duality transformations provide e.g new examples of coisotropic A-branes on Kaehler manifolds (which are not necessarily hyper-Kaehler). Finally, by dualizing a chiral and a twisted chiral field to a semi-chiral multiplet, we initiate the study of D-branes in bihermitian geometries where the cokernel of the commutator of the complex structures is non-empty.
Line bundle twisted chiral de Rham complex and bound states of D-branes on toric manifolds
International Nuclear Information System (INIS)
Parkhomenko, S.E.
2014-01-01
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 3 . Then we twist chiral de Rham complex by sheaves localized on positive codimension submanifolds in P 2 and calculate in each case the elliptic genus. In the last example the elliptic genus of chiral de Rham complex on P 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
Discrete gauge symmetries in discrete MSSM-like orientifolds
International Nuclear Information System (INIS)
Ibáñez, L.E.; Schellekens, A.N.; 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 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 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.
M5-branes, orientifolds, and S-duality
Energy Technology Data Exchange (ETDEWEB)
Hwang, Yoonseok [Department of Physics and Astronomy & Center for Theoretical Physics,Seoul National University, 1 Gwanak-ro, Seoul (Korea, Republic of); Kim, Joonho [School of Physics, Korea Institute for Advanced Study,85 Hoegiro, Seoul (Korea, Republic of); Kim, Seok [Department of Physics and Astronomy & Center for Theoretical Physics,Seoul National University, 1 Gwanak-ro, Seoul (Korea, Republic of)
2016-12-29
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{sup 5} partition functions that correspond to the 6d (2,0) superconformal indices. Our SO(2N) index takes the form of the vacuum character of W{sub 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{sup 5}.
Experimental data report for transient flow calibration facility tests IIB101, IIB102 and IIB201
International Nuclear Information System (INIS)
Wambach, J.L.
1980-01-01
Thermal-hydraulic response data are presented for the transient performance tests of a pitot tube rake (IIB201) and a modular drag disc-turbine transducer (DTT) rake (IIB101, IIB102). The tests were conducted in a system which provided full scale simulation of the pressure vessel and broken loop hot leg piping of the Loss of Fluid Test Facility (LOFT). A load cell system was used to provide a reference mass flow rate measurement
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.)
Systematics of IIB spinorial geometry
Gran, U.; Gutowski, J.; Papadopoulos, G.; Roest, D.
2005-01-01
We reduce the classification of all supersymmetric backgrounds of IIB supergravity to the evaluation of the Killing spinor equations and their integrability conditions, which contain the field equations, on five types of spinors. This extends the work of [hep-th/0503046] to IIB supergravity. We give the expressions of the Killing spinor equations on all five types of spinors. In this way, the Killing spinor equations become a linear system for the fluxes, geometry and spacetime derivatives of...
An Exact Relation for N=1 Orientifold Field Theories with Arbitrary Superpotential
Armoni, Adi; Shifman, M
2004-01-01
We discuss a nonperturbative relation for orientifold parent/daughter pairs of supersymmetric theories with an arbitrary tree-level superpotential. We show that super-Yang-Mills (SYM) theory with matter in the adjoint representation at N-->infinity, is equivalent to a SYM theory with matter in the antisymmetric representation and a related superpotential. The gauge symmetry breaking patterns match in these theories too. The moduli spaces in the limiting case of a vanishing superpotential are also discussed. Finally we argue that there is an exact mapping between the effective superpotentials of two finite-N theories belonging to an orientifold pair.
Exact Results in Non-Supersymmetric Large N Orientifold Field Theories
Armoni, Adi; Veneziano, Gabriele
2003-01-01
We consider non-supersymmetric large N orientifold field theories. Specifically, we discuss a gauge theory with a Dirac fermion in the anti-symmetric tensor representation. We argue that, at large N and in a large part of its bosonic sector, this theory is non-perturbatively equivalent to N=1 SYM, so that exact results established in the latter (parent) theory also hold in the daughter orientifold theory. In particular, the non-supersymmetric theory has an exactly calculable bifermion condensate, exactly degenerate parity doublets, and a vanishing cosmological constant (all this to leading order in 1/N).
International Nuclear Information System (INIS)
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 nonvanishing 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 nonlocal 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 D dimensions and obtaining a local effective action
Massless spectra and gauge couplings at one-loop on non-factorisable toroidal orientifolds
Berasaluce-González, Mikel; Honecker, Gabriele; Seifert, Alexander
2018-01-01
So-called 'non-factorisable' toroidal orbifolds can be rewritten in a factorised form as a product of three two-tori by imposing an additional shift symmetry. This finding of Blaszczyk et al. [1] provides a new avenue to Conformal Field Theory methods, by which the vector-like massless matter spectrum - and thereby the type of gauge group enhancement on orientifold invariant fractional D6-branes - and the one-loop corrections to the gauge couplings in Type IIA orientifold theories can be computed in addition to the well-established chiral matter spectrum derived from topological intersection numbers among three-cycles. We demonstrate this framework for the Z4 × ΩR orientifolds on the A3 ×A1 ×B2-type torus. As observed before for factorisable backgrounds, also here the one-loop correction can drive the gauge groups to stronger coupling as demonstrated by means of a four-generation Pati-Salam example.
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...
The type IIB string axiverse and its low-energy phenomenology
International Nuclear Information System (INIS)
Cicoli, Michele; Goodsell, Mark D.; Ringwald, Andreas
2012-06-01
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.
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.
The Cosmological Constant and Domain Walls in Orientifold Field Theories and N=1 Gluodynamics
Armoni, Adi
2003-01-01
We discuss domain walls and vacuum energy density (cosmological constant) in N=1 gluodynamics and in non-supersymmetric large N orientifold field theories which have been recently shown to be planar equivalent (in the boson sector) to N=1 gluodynamics. A relation between the vanishing force between two parallel walls and vanishing cosmological constant is pointed out. This relation may explain why the cosmological constant vanishes in the orientifold field theory at leading order although the hadronic spectrum of this theory does not contain fermions in the limit N-->infinity. The cancellation is among even and odd parity bosonic contributions, due to NS-NS and R-R cancellations in the annulus amplitude of the underlying string theory. We use the open-closed string channel duality to describe interaction between the domain walls which is interpreted as the exchange of composite ``dilatons'' and ``axions'' coupled to the walls. Finally, we study some planar equivalent pairs in which both theories in the parent...
Generalized IIB supergravity from exceptional field theory
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Baguet, Arnaud; Magro, Marc; Samtleben, Henning [Laboratoire de Physique, Université Claude Bernard Lyon 1, Ens de Lyon, CNRS,F-69342 Lyon (France)
2017-03-20
The background underlying the η-deformed AdS{sub 5}×S{sup 5} sigma-model is known to satisfy a generalization of the IIB supergravity equations. Their solutions are related by T-duality to solutions of type IIA supergravity with non-isometric linear dilaton. We show how the generalized IIB supergravity equations can be naturally obtained from exceptional field theory. Within this manifestly duality covariant formulation of maximal supergravity, the generalized IIB supergravity equations emerge upon imposing on the fields a simple Scherk-Schwarz ansatz which respects the section constraint.
Heterotic and type II orientifold compactifications on SU(3) structure manifolds
International Nuclear Information System (INIS)
Benmachiche, I.
2006-07-01
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.)
More supersymmetric standardlike models from intersecting D6-branes on type IIA orientifolds
International Nuclear Information System (INIS)
Cvetic, Mirjam; Papadimitriou, Ioannis
2003-01-01
We present new classes of supersymmetric standardlike models from a type IIA T 6 /(Z 2 xZ 2 ) orientifold with intersecting D6-branes. D6-branes can wrap general supersymmetric three-cycles of T 6 =T 2 xT 2 xT 2 , and any T 2 is allowed to be tilted. The models still suffer from additional exotics; however, we obtain solutions with fewer Higgs doublets, as well as models with all three families of left-handed quarks and leptons arising from the same intersecting sector, and examples of a genuine left-right symmetric model with three copies of left-handed and right-handed families of quarks and leptons
On (orientifold of) type IIA on a compact Calabi-Yau
International Nuclear Information System (INIS)
Misra, A.
2004-01-01
We study the gauged sigma model and its mirror Landau-Ginsburg model corresponding to type IIA on the Fermat degree-24 hypersurface in WCP 4 [1,1,2,8,12] (whose blow-up gives the smooth CY 3 (3,243)) away from the orbifold singularities, and its orientifold by a freely-acting antiholomorphic involution. We derive the Picard-Fuchs equation obeyed a period integral of a parent N=2 type IIA theory. We obtain the Meijer's basis of solutions to the equation in the large and small complex structure limits (on the mirror Landau-Ginsburg side) of the abovementioned Calabi-Yau, and make some remarks about the monodromy properties associated at the same and another MATHEMATICAlly interesting point. Based on a recently shown N=1 four-dimensional triality between Heterotic on the self-mirror Calabi-Yau CY 3 (11,11), M theory on CY 3 (3,243) x S 1 /(Z 2 ) and F-theory on an elliptically fibered CY 4 with the base given by CP 1 x Enriques surface, we first give a heuristic argument that there can be no superpotential generated in the orientifold of of CY 3 (3,243), and then explicitly verify the same using a mirror symmetry formulation for the abovementioned hypersurface away from its orbifold singularities. We then discuss briefly the sigma model and the mirror Landau-Ginsburg model corresponding to the resolved Calabi-Yau as well. (Abstract Copyright [2004], Wiley Periodicals, Inc.)
Towards Matrix Models in IIB Superstrings
Olesen, P.
1997-01-01
I review the properties of a matrix action of relevance for IIB superstrings. This model generalizes the action proposed by Ishibashi, Kawai, Kitazawa, and Tsuchiya by introducing an auxillary field Y, which is the matrix version of the auxillary field g in the Schild action.
Minkowski vacuum transitions in (nongeometric) flux compactifications
International Nuclear Information System (INIS)
Herrera-Suarez, Wilberth; Loaiza-Brito, Oscar
2010-01-01
In this work we study the generalization of twisted homology to geometric and nongeometric backgrounds. In the process, we describe the necessary conditions to wrap a network of D-branes on twisted cycles. If the cycle is localized in time, we show how by an instantonic brane mediation, some D-branes transform into fluxes on different backgrounds, including nongeometric fluxes. As a consequence, we show that in the case of a IIB six-dimensional torus compactification on a simple orientifold, the flux superpotential is not invariant by this brane-flux transition, allowing the connection among different Minkowski vacuum solutions. For the case in which nongeometric fluxes are turned on, we also discuss some topological restrictions for the transition to occur. In this context, we show that there are some vacuum solutions protected to change by a brane-flux transition.
Type IIA on a compact Calabi-Yau and D=11 supergravity uplift of its orientifold
International Nuclear Information System (INIS)
Misra, A.
2004-01-01
Using the prescription of K. Hori and C. Vafa for defining period integrals in the Landau-Ginsburg theory for compact Calabi-Yau's, we obtain the Picard-Fuchs equation and the Meijer basis of solutions for the compact Calabi-Yau CY 3 (3,243) expressed as a degree-24 Fermat hypersurface after resolution of the orbifold singularities. The importance of the method lies in the ease with which one can consider the large and small complex structure limits, as well as the ability to get the ''ln''-terms in the periods without having to parametrically differentiate infinite series. We consider in detail the evaluation of the monodromy matrix in the large and small complex structure limits. We also consider the action of the freely acting antiholomorphic involution on D=11 supergravity compactified on CY 3 (3,243) x S 1 and obtain the Kaehler potential for the same in the limit of large volume of the Calabi-Yau. As a by-product, we also give a conjecture for the action of the orientation-reversing antiholomorphic involution on the periods, given its action on the cohomology, using a canonical (co)homology basis. Finally, we also consider showing a null superpotential on the orientifold of type IIA on CY 3 (3,243), having taken care of the orbifold singularities. (Abstract Copyright [2004], Wiley Periodicals, Inc.)
Forbidden territories in the string landscape
Kumar, Alok; Mukhopadhyay, Subir; Ray, Koushik
2007-12-01
Problems of stabilizing moduli of the type-IIB string theory on toroidal orientifolds T6/Z2, in presence of worldvolume fluxes on various D-branes, are considered. For Z2 actions, introducing either O9 or O3 planes, we rule out the possibility of moduli stabilization in a wide class of models with Script N = 1 supersymmetry, characterized by the type of fluxes turned on along D-brane worldvolume. Our results, in particular, imply that Abelian worldvolume fluxes can not by themselves stabilize closed string moduli, in a consistent supersymmtric model, for above orientifold compactifications. We also discuss other Z2 orientifolds of T6 and show that certain other brane wrappings are also ruled out by similar consistency requirements. In specific setups we consider examples with D9-branes wrapping on a complex three-torus with its world-volume fluxes taken to be semi-homogeneous bundles and D7-branes wrapping holomorphic four-cycles of the complex three-torus carrying world-volume fluxes.
New families of interpolating type IIB backgrounds
Minasian, Ruben; Petrini, Michela; Zaffaroni, Alberto
2010-04-01
We construct new families of interpolating two-parameter solutions of type IIB supergravity. These correspond to D3-D5 systems on non-compact six-dimensional manifolds which are mathbb{T}2 fibrations over Eguchi-Hanson and multi-center Taub-NUT spaces, respectively. One end of the interpolation corresponds to a solution with only D5 branes and vanishing NS three-form flux. A topology changing transition occurs at the other end, where the internal space becomes a direct product of the four-dimensional surface and the two-torus and the complexified NS-RR three-form flux becomes imaginary self-dual. Depending on the choice of the connections on the torus fibre, the interpolating family has either mathcal{N}=2 or mathcal{N}=1 supersymmetry. In the mathcal{N}=2 case it can be shown that the solutions are regular.
Is inflation from unwinding fluxes IIB?
Energy Technology Data Exchange (ETDEWEB)
Gautason, Fridrik Freyr [Instituut voor Theoretische Fysica, K.University Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium); Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS,Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Schillo, Marjorie; Riet, Thomas Van [Instituut voor Theoretische Fysica, K.University Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium)
2017-03-07
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.
IIB backgrounds with five-form flux
International Nuclear Information System (INIS)
Gran, U.; Gutowski, J.; Papadopoulos, G.
2008-01-01
We investigate all N=2 supersymmetric IIB supergravity backgrounds with non-vanishing five-form flux. The Killing spinors have stability subgroups Spin(7) x R 8 , SU(4) x R 8 and G 2 . In the SU(4) x R 8 case, two different types of geometry arise depending on whether the Killing spinors are generic or pure. In both cases, the backgrounds admit a null Killing vector field which leaves invariant the SU(4) x R 8 structure, and an almost complex structure in the directions transverse to the lightcone. In the generic case, the twist of the vector field is trivial but the almost complex structure is non-integrable, while in the pure case the twist is non-trivial but the almost complex structure is integrable and associated with a relatively balanced Hermitian structure. The G 2 backgrounds admit a time-like Killing vector field and two spacelike closed one-forms, and the seven directions transverse to these admit a co-symplectic G 2 structure. The Spin(7) x R 8 backgrounds are pp-waves propagating in an eight-dimensional manifold with holonomy Spin(7). In addition we show that all the supersymmetric solutions of simple five-dimensional supergravity with a time-like Killing vector field, which include the AdS 5 black holes, lift to SU(4) x R 8 pure Killing spinor IIB backgrounds. We also show that the LLM solution is associated with a co-symplectic co-homogeneity one G 2 manifold which has principal orbit S 3 xS 3
Invasive cervical carcinoma (Stages IB-IIB)
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Sironi, S.; Zanello, A.; Rodighiero, M.G.; Vanzulli, A.; Del Maschio, A.; Taccagni, G.L.; Belloni, C.
1991-01-01
In the patients with invasive cervical carcinoma, the accurate assessment of parametrial invasion greatly affects the therapeutic choice between surgery and radiation therapy. As a matter of fact, surgery is usually performed only in the patients with carcinoma confined to the cervix, whereas those with parametrial involvement, or more advanced stages, are treated with radiation therapy. This prospective study was aimed at investigating the comparative adequecy of CT and MR imaging in assessing parametrial status in the patients with invasive cervical cancer. Twenty-one consecutive patients, with histologic diagnosis of cervical carcinoma, were investigated. All of them were clinically considered as having invasive cervical cancer (FIGO stage IB-IIB) and subsequently underwent surgery. In all cases, detailed histology of the parametrium was obtained. Pathological data were compared with CT and MR findings in all cases. As for assessing parametrial involvement by cancer, CT had 62% accuracy, 63% sensitivity, and 60% specificity, versus MR imaging 81% accuracy, 69% sensitivity, and 80% specificify. Therefore, MR imaging appears to be superior to CT in assessing the parametrial status of patients with invasive cervical carcinoma; the method yields valuable information for treatment planning
TYPE IIb SUPERNOVAE WITH COMPACT AND EXTENDED PROGENITORS
International Nuclear Information System (INIS)
Chevalier, Roger A.; Soderberg, Alicia M.
2010-01-01
The classic example of a Type IIb supernova is SN 1993J, which had a cool extended progenitor surrounded by a dense wind. There is evidence for another category of Type IIb supernova that has a more compact progenitor with a lower density, probably fast, wind. Distinguishing features of the compact category are weak optical emission from the shock heated envelope at early times, nonexistent or very weak H emission in the late nebular phase, rapidly evolving radio emission, rapid expansion of the radio shell, and expected nonthermal as opposed to thermal X-ray emission. Type IIb supernovae that have one or more of these features include SNe 1996cb, 2001ig, 2003bg, 2008ax, and 2008bo. All of these with sufficient radio data (the last four) show evidence for presupernova wind variability. We estimate a progenitor envelope radius ∼1 x 10 11 cm for SN 2008ax, a value consistent with a compact Wolf-Rayet progenitor. Supernovae in the SN 1993J extended category include SN 2001gd and probably the Cas A supernova. We suggest that the compact Type IIb events be designated Type cIIb and the extended ones Type eIIb. The H envelope mass dividing these categories is ∼0.1 M sun .
Elitzur, Shmuel; Sarkisian, G; Elitzur, Shmuel; Rabinovici, Eliezer; Sarkissian, Gor
1999-01-01
We discuss the effect of relevant boundary terms on the nature of branes. This is done for toroidal and orbifold compactifications of the bosonic string. Using the relative minimalization of the boundary entropy as a guiding principle, we uncover the more stable boundary conditions at different regions of moduli space. In some cases, Neumann boundary conditions dominate for small radii while Dirichlet boundary conditions dominate for large radii. The c=1 and c=2 moduli spaces are studied in some detail. The antisymmetric background field B is found to have a more limited role in the case of Dirichlet boundary conditions. This is due to some topological considerations. The results are subjected to T-duality tests and the special role of the points in moduli space fixed under T-duality is explained from least-action considerations.
Conformal symmetry for rotating D-branes
International Nuclear Information System (INIS)
Cao Liming; Matsuo, Yoshinori; Tsukioka, Takuya; Yoo, Chul-Moon
2009-01-01
We apply the Kerr/CFT correspondence to the rotating black p-brane solutions. These solutions give the simplest examples from string theory point of view. Their near horizon geometries have structures of AdS, even though black p-brane solutions do not have AdS-like structures in the non-rotating case. The microscopic entropy which can be calculated via the Cardy formula exactly agrees with Bekenstein-Hawking entropy.
D-brane solutions under market panic
Pincak, Richard
The relativistic quantum mechanic approach is used to develop stock market dynamics. The relativistic is conceptional here as the meaning of big external volatility or volatility shock on a financial market. We used a differential geometry approach with the parallel transport of prices to obtain a direct shift of the stock price movement. The prices are represented here as electrons with different spin orientation. Up and down orientations of the spin particle are likened here to an increase or a decrease of stock prices. The parallel transport of stock prices is enriched by Riemann curvature, which describes some arbitrage opportunities in the market. To solve the stock-price dynamics, we used the Dirac equation for bispinors on the spherical brane-world. We found out that when a spherical brane is abbreviated to the disk on the equator, we converge to the ideal behavior of financial market where Black-Scholes as well as semi-classical equations are sufficient. Full spherical brane-world scenarios can describe non-equilibrium market behavior where all arbitrage opportunities as well as transaction costs are taken into account. Real application of the model to the option pricing was done. The model developed in this paper brings quantitative different results of option pricing dynamics in the case of nonzero Riemann curvature.
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
IIB solutions with N>28 Killing spinors are maximally supersymmetric
International Nuclear Information System (INIS)
Gran, U.; Gutowski, J.; Papadopoulos, G.; Roest, D.
2007-01-01
We show that all IIB supergravity backgrounds which admit more than 28 Killing spinors are maximally supersymmetric. In particular, we find that for all N>28 backgrounds the supercovariant curvature vanishes, and that the quotients of maximally supersymmetric backgrounds either preserve all 32 or N<29 supersymmetries
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
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.
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.
Supersymmetric AdS6 solutions of type IIB supergravity
International Nuclear Information System (INIS)
Kim, Hyojoong; Kim, Nakwoo; Suh, Minwoo
2015-01-01
We study the general requirement for supersymmetric AdS 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 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
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.
Superdualities, brane tensions and massive IIA/IIB duality
International Nuclear Information System (INIS)
Lavrinenko, I.V.; Lue, H.; Pope, C.N.; Stelle, K.S.
1999-01-01
The gauge transformations of p-form fields in supergravity theories acquire a non-commuting character when one introduces potentials both for the theory's original field strengths and for their duals. This has previously been shown in the 'doubled' formalism for maximal supergravities, where a generalised duality relation between original and dual field strengths replaces the equations of motion. In the doubled formalism, the gauge transformations generate a superalgebra, and the corresponding symmetries have accordingly been called 'superdualities'. The corresponding Noether charges form a representation of the cohomology ring on the space-time manifold. In this paper, we show that the gauge symmetry superalgebra implies certain non-trivial relations among the various p-brane tensions, which can straightforwardly be read off from the superalgebra commutation relations. This provides an elegant derivation of the brane-tension relations purely within a given theory, without the need to make use of duality relations between different theories, such as the type IIA/IIB T-duality, although the results are consistent with such dualities. We present the complete set of brane-tension relations in M-theory, in the type IIA and type IIB theories, and in all the lower-dimensional maximal supergravities. We also construct a doubled formalism for massive type IIA supergravity, and this enables us to obtain the brane-tension relations involving the D8-brane, purely within the framework of the massive IIA theory. We also obtain explicit transformations for the nine-dimensional T-duality between the massive type IIA theory and the Scherk-Schwarz reduced type IIB theory
SEARCH FOR PRECURSOR ERUPTIONS AMONG TYPE IIB SUPERNOVAE
Energy Technology Data Exchange (ETDEWEB)
Strotjohann, Nora L.; Ofek, Eran O.; Gal-Yam, Avishay; Yaron, Ofer [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Kulkarni, Shrinivas R.; Cao, Yi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Shaviv, Nir J. [School of Natural Sciences, Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 08540 (United States); Fremling, Christoffer; Sollerman, Jesper [The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-10691 Stockholm (Sweden); Kasliwal, Mansi M. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Nugent, Peter E. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Arcavi, Iair [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93111 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Laher, Russ; Surace, Jason [Spitzer Science Center, California Institute of Technology, M/S 314-6, Pasadena, CA 91125 (United States)
2015-10-01
The progenitor stars of several Type IIb supernovae (SNe) show indications of extended hydrogen envelopes. These envelopes might be the outcome of luminous energetic pre-explosion events, so-called precursor eruptions. We use the Palomar Transient Factory (PTF) pre-explosion observations of a sample of 27 nearby SNe IIb to look for such precursors during the final years prior to the SN explosion. No precursors are found when combining the observations in 15-day bins, and we calculate the absolute-magnitude-dependent upper limit on the precursor rate. At the 90% confidence level, SNe IIb have on average <0.86 precursors as bright as an absolute R-band magnitude of −14 in the final 3.5 years before the explosion and <0.56 events over the final year. In contrast, precursors among SNe IIn have a ≳5 times higher rate. The kinetic energy required to unbind a low-mass stellar envelope is comparable to the radiated energy of a few-weeks-long precursor that would be detectable for the closest SNe in our sample. Therefore, mass ejections, if they are common in such SNe, are radiatively inefficient or have durations longer than months. Indeed, when using 60-day bins, a faint precursor candidate is detected prior to SN 2012cs (∼2% false-alarm probability). We also report the detection of the progenitor of SN 2011dh that does not show detectable variability over the final two years before the explosion. The suggested progenitor of SN 2012P is still present, and hence is likely a compact star cluster or an unrelated object.
Altered inhibition in Tuberous Sclerosis and Type IIb cortical dysplasia
Talos, Delia M.; Sun, Hongyu; Kosaras, Bela; Joseph, Annelise; Folkerth, Rebecca D.; Poduri, Annapurna; Madsen, Joseph R.; Black, Peter M.; Jensen, Frances E.
2012-01-01
Objective The most common neurological symptom of tuberous sclerosis complex (TSC) and focal cortical dysplasia (FCD) is early-life refractory epilepsy. As previous studies have shown enhanced excitatory glutamatergic neurotransmission in TSC and FCD brains, we hypothesized that neurons associated with these lesions may also express altered GABAA receptor (GABAAR)-mediated inhibition. Methods Expression of the GABAAR subunitsα1 and α4, the Na+-K+-2Cl− (NKCC1), and the K+−Cl− (KCC2) transporters in human TSC and FCD Type II specimens were analyzed by Western blot and double label immunocytochemistry. GABAAR responses in dysplastic neurons from a single case of TSC were measured by perforated-patch recording and compared to normal-appearing cortical neurons from a non-TSC epilepsy case. Results TSC and FCD Type IIb lesions demonstrated decreased expression of the GABAAR α1, increased NKCC1 and decreased KCC2 levels. In contrast, FCD Type IIa lesions showed decreased α4, and increased expression of both NKCC1 and KCC2 transporters. Patch clamp recordings from dysplastic neurons in acute slices from TSC tubers demonstrated excitatory GABAAR responses that were significantly attenuated by the NKCC1 inhibitor bumetanide, in contrast to hyperpolarizing GABAAR-mediated currents in normal neurons from non-TSC cortical slices. Interpretation Expression and function of GABAARs in TSC and FCD IIb suggests the relative benzodiazepine insensitivity and more excitatory action of GABA compared to FCD IIa. These factors may contribute to resistance of seizure activity to anticonvulsants that increase GABAergic function, and may justify add-on trials of the NKCC1 inhibitor bumetanide for the treatment of TSC and FCD Type IIb related epilepsy. PMID:22447678
String necklaces and primordial black holes from type IIB strings
International Nuclear Information System (INIS)
Lake, Matthew; Thomas, Steve; Ward, John
2009-01-01
We consider a model of static cosmic string loops in type IIB string theory, where the strings wrap cycles within the internal space. The strings are not topologically stabilised, however the presence of a lifting potential traps the windings giving rise to kinky cycloops. We find that PBH formation occurs at early times in a small window, whilst at late times we observe the formation of dark matter relics in the scaling regime. This is in stark contrast to previous predictions based on field theoretic models. We also consider the PBH contribution to the mass density of the universe, and use the experimental data to impose bounds on the string theory parameters.
Vertex operators of ghost number three in Type IIB supergravity
International Nuclear Information System (INIS)
Mikhailov, Andrei
2016-01-01
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.
Schroedinger invariant solutions of type IIB with enhanced supersymmetry
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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.)
Type IIB flux vacua from G-theory I
International Nuclear Information System (INIS)
Candelas, Philip; Constantin, Andrei; Damian, Cesar; Larfors, Magdalena; Morales, Jose Francisco
2015-01-01
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×ℂ with the metric, dilaton and flux potentials varying along 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 http://arxiv.org/abs/1411.4786. We build a precise dictionary between fluxes in the global solutions and the geometry of an auxiliary K3 surface fibered over 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 of the fiber.
Type IIB flux vacua from G-theory I
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Candelas, Philip [Mathematical Institute, University of Oxford,Andrew Wiles Building, Radcliffe Observatory Quarter,Woodstock Road, Oxford, OX2 6GG (United Kingdom); Constantin, Andrei [Department of Physics and Astronomy, Uppsala University,SE-751 20, Uppsala (Sweden); Damian, Cesar [Departamento de Fisica, DCI, Campus Leon, Universidad de Guanajuato,C.P. 37150, Leon, Guanajuato (Mexico); Larfors, Magdalena [Department of Physics and Astronomy, Uppsala University,SE-751 20, Uppsala (Sweden); Morales, Jose Francisco [INFN - Sezione di Roma “TorVergata”, Dipartimento di Fisica,Università di Roma “TorVergata”, Via della Ricerca Scientica, 00133 Roma (Italy)
2015-02-27
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{sup 4}×ℂ with the metric, dilaton and flux potentials varying along ℂ and the flux potentials oriented along T{sup 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 http://arxiv.org/abs/1411.4786. We build a precise dictionary between fluxes in the global solutions and the geometry of an auxiliary K3 surface fibered over ℂℙ{sup 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 of the fiber.
Inner-shell photoionization of group-IIB atoms
International Nuclear Information System (INIS)
Kutzner, M.; Tidwell, C.; Vance, S.E.; Radojevic, V.
1994-01-01
Total and partial photoionization cross sections, branching ratios, and angular-distribution asymmetry parameters for inner subshells (nl,l≥2) of the group-IIB elements zinc, cadmium, and mercury have been calculated in both the relativistic random-phase approximation and the relativistic random-phase approximation modified to include relaxation. Comparisons are made between the results of the two theoretical methods and with experiment where available. The present theoretical results for the 3d inner-shell photoionization of zinc are not in accord with experiment. We confirm previous work [S. L. Carter and H. P. Kelly, J. Phys. B 11, 2467 (1978)] which demonstrated that relaxation is an important effect in photoionization of the 4d subshell of atomic cadmium. It is also found that the inclusion of relaxation effects resolves a discrepancy between theory and experiment for the 4f inner-shell photoionization of atomic mercury
Aspects of Moduli Stabilization in Type IIB String Theory
Directory of Open Access Journals (Sweden)
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.
Focal cortical dysplasia type IIa and IIb: MRI aspects in 118 cases proven by histopathology
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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.)
Dual mechanism of integrin αIIbβ3 closure in procoagulant platelets.
Mattheij, Nadine J A; Gilio, Karen; van Kruchten, Roger; Jobe, Shawn M; Wieschhaus, Adam J; Chishti, Athar H; Collins, Peter; Heemskerk, Johan W M; Cosemans, Judith M E M
2013-05-10
Inactivation of integrin αIIbβ3 reverses platelet aggregate formation upon coagulation. Platelets from patient (Scott) and mouse (Capn1(-/-) and Ppif(-/-)) blood reveal a dual mechanism of αIIbβ3 inactivation: by calpain-2 cleavage of integrin-associated proteins and by cyclophilin D/TMEM16F-dependent phospholipid scrambling. These data provide novel insight into the switch mechanisms from aggregating to procoagulant platelets. Aggregation of platelets via activated integrin αIIbβ3 is a prerequisite for thrombus formation. Phosphatidylserine-exposing platelets with a key role in the coagulation process disconnect from a thrombus by integrin inactivation via an unknown mechanism. Here we show that αIIbβ3 inactivation in procoagulant platelets relies on a sustained high intracellular Ca(2+), stimulating intracellular cleavage of the β3 chain, talin, and Src kinase. Inhibition of calpain activity abolished protein cleavage, but only partly suppressed αIIbβ3 inactivation. Integrin αIIbβ3 inactivation was unchanged in platelets from Capn1(-/-) mice, suggesting a role of the calpain-2 isoform. Scott syndrome platelets, lacking the transmembrane protein TMEM16F and having low phosphatidylserine exposure, displayed reduced αIIbβ3 inactivation with the remaining activity fully dependent on calpain. In platelets from Ppif(-/-) mice, lacking mitochondrial permeability transition pore (mPTP) formation, agonist-induced phosphatidylserine exposure and αIIbβ3 inactivation were reduced. Treatment of human platelets with cyclosporin A gave a similar phenotype. Together, these data point to a dual mechanism of αIIbβ3 inactivation via calpain(-2) cleavage of integrin-associated proteins and via TMEM16F-dependent phospholipid scrambling with an assistant role of mPTP formation.
A critical role for topoisomerase IIb and DNA double strand breaks in transcription.
Calderwood, Stuart K
2016-05-26
Recent studies have indicated a novel role for topoisomerase IIb in transcription. Transcription of heat shock genes, serum-induced immediate early genes and nuclear receptor-activated genes, each required DNA double strands generated by topoisomerase IIb. Such strand breaks seemed both necessary and sufficient for transcriptional activation. In addition, such transcription was associated with initiation of the DNA damage response pathways, including the activation of the enzymes: ataxia-telangiectasia mutated (ATM), DNA-dependent protein kinase and poly (ADP ribose) polymerase 1. DNA damage response signaling was involved both in transcription and in repair of DNA breaks generated by topoisomerase IIb.
Thornton, Michael A; Zhang, Chunyan; Kowalska, Maria A; Poncz, Mortimer
2002-11-15
The alphaIIb/beta3-integrin receptor is present at high levels only in megakaryocytes and platelets. Its presence on platelets is critical for hemostasis. The tissue-specific nature of this receptor's expression is secondary to the restricted expression of alphaIIb, and studies of the alphaIIb proximal promoter have served as a model of a megakaryocyte-specific promoter. We have examined the alphaIIb gene locus for distal regulatory elements. Sequence comparison between the human (h) and murine (m) alphaIIb loci revealed high levels of conservation at intergenic regions both 5' and 3' to the alphaIIb gene. Additionally, deoxyribonuclease (DNase) I sensitivity mapping defined tissue-specific hypersensitive (HS) sites that coincide, in part, with these conserved regions. Transgenic mice containing various lengths of the h(alpha)IIb gene locus, which included or excluded the various conserved/HS regions, demonstrated that the proximal promoter was sufficient for tissue specificity, but that a region 2.5 to 7.1 kb upstream of the h(alpha)IIb gene was necessary for consistent expression. Another region 2.2 to 7.4 kb downstream of the gene enhanced expression 1000-fold and led to levels of h(alpha)IIb mRNA that were about 30% of the native m(alpha)IIb mRNA level. These constructs also resulted in detectable h(alpha)IIb/m(beta)3 on the platelet surface. This work not only confirms the importance of the proximal promoter of the alphaIIb gene for tissue specificity, but also characterizes the distal organization of the alphaIIb gene locus and provides an initial localization of 2 important regulatory regions needed for the expression of the alphaIIb gene at high levels during megakaryopoiesis.
On a supersymmetric completion of the R4 term in IIB supergravity
International Nuclear Information System (INIS)
Haro, Sebastian de; Sinkovics, Annamaria; Skenderis, Kostas
2003-01-01
We analyze the possibility of constructing a supersymmetric invariant that contains the R 4 term among its components as a superpotential term in type IIB on-shell superspace. We consider a scalar superpotential, i.e. an arbitrary holomorphic function of a chiral scalar superfield. In general, type IIB superspace does not allow for the existence of chiral superfields, but the obstruction vanishes for a specific superfield, the dilaton superfield. This superfield contains all fields of type IIB supergravity among its components, and its existence is implied by the solution of the Bianchi identities. The construction requires the existence of an appropriate chiral measure, and we find an obstruction to the existence of such a measure. The obstruction is closely related to the obstruction for the existence of chiral superfields and is non-linear in the fields. These results imply that the type IIB superinvariant related to the R 4 term is not associated with a scalar chiral superpotential
The G2 spinorial geometry of supersymmetric IIB backgrounds
International Nuclear Information System (INIS)
Gran, U; Gutowski, J; Papadopoulos, G
2006-01-01
We solve the Killing spinor equations of supersymmetric IIB backgrounds which admit one supersymmetry and the Killing spinor has stability subgroup G 2 in Spin(9, 1) x U(1). We find that such backgrounds admit a timelike Killing vector field and the geometric structure of the spacetime reduces from Spin(9, 1) x U(1) to G 2 . We determine the type of G 2 structure that the spacetime admits by computing the covariant derivatives of the spacetime forms associated with the Killing spinor bilinears. We also solve the Killing spinor equations of backgrounds with two supersymmetries and Spin(7) x R 8 -invariant spinors, and four supersymmetries with SU(4) x R 8 - and with G 2 -invariant spinors. We show that the Killing spinor equations factorize in two sets, one involving the geometry and the 5-form flux, and the other the 3-form flux and the scalars. In the Spin(7) x R 8 and SU(4) x R 8 cases, the spacetime admits a parallel null vector field and so the spacetime metric can be locally described in terms of Penrose coordinates adapted to the associated rotation free, null, geodesic congruence. The transverse space of the congruence is a Spin(7) and a SU(4) holonomy manifold, respectively. In the G 2 case, all the fluxes vanish and the spacetime is the product of a three-dimensional Minkowski space with a holonomy G 2 manifold
Group IIB-VIA semiconductor oxide cluster ions
Jayasekharan, Thankan
2018-05-01
Metal oxide cluster ions, MnOm± (M = Zn, Cd) and HgnOm- of various stoichiometry have been generated from solid IIB-VIA semiconductor oxides targets, (ZnO(s), CdO(s), and HgO(s)) by using pulse laser desorption ionization time of flight mass spectrometry with a laser of λ = 355 nm. Analysis of mass spectral data indicates the formation of stoichiometric cluster ions viz., (ZnO)n=1-30+ and (CdO)n=1-40+ along with -O bound anions, (ZnO)n=1-30O-, (CdO)n=1-40O- and (HgO)n=1-36O- from their respective solids. Further, metal oxoanions such as ZnOn=2,3-, CdOn=2,3,6-, and HgOn=2,3,6,7- have also been noted signifying the higher coordination ability of both Cd and Hg with O/O2/O3 species.
VLBI OBSERVATIONS OF THE NEARBY TYPE IIb SUPERNOVA 2011dh
International Nuclear Information System (INIS)
Bietenholz, M. F.; Brunthaler, A.; Soderberg, A. M.; Zauderer, B.; Krauss, M.; Chomiuk, L.; Rupen, M. P.; Bartel, N.
2012-01-01
We report on phase-referenced very long baseline interferometry radio observations of the Type IIb supernova 2011dh, at times t = 83 days and 179 days after the explosion and at frequencies, respectively, of 22.2 and 8.4 GHz. We detected SN 2011dh at both epochs. At the first epoch only an upper limit on SN 2011dh's angular size was obtained, but at the second epoch, we determine the angular radius of SN 2011dh's radio emission to be 0.25 ± 0.08 mas by fitting a spherical shell model directly to the visibility measurements. At a distance of 8.4 Mpc, this angular radius corresponds to a time-averaged (since t = 0) expansion velocity of the forward shock of 21, 000 ± 7000 km s –1 . Our measured values of the radius of the emission region are in excellent agreement with those derived from fitting synchrotron self-absorbed models to the radio spectral energy distribution, providing strong confirmation for the latter method of estimating the radius. We find that SN 2011dh's radius evolves in a power-law fashion, with R∝t 0.92±0.10 .
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...
Duality covariant type-IIB supersymmetry and nonperturbative consequences
International Nuclear Information System (INIS)
Bars, I.
1997-01-01
Type-IIB supersymmetric theories have an SL(2,Z) invariance, known as U duality, which controls the nonperturbative 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 five-branes 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 nonperturbative 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 black holes constructed from D-1-branes and D-5-branes. In the latter case the nonperturbative coupling dependence of the BPS mass and renormalization is computed for the first time in this paper. It is further argued that the moduli dependence of the superalgebra provides hints for four more dimensions beyond ten, such that the superalgebra is embedded in a fundamental theory which would be covariant under SO(11,3). An outline is given for a matrix theory in 14 dimensions that would be consistent with M(atrix) theory as well as with the above observations. copyright 1997 The American Physical Society
COMPARISON OF DIVERSITY OF TYPE IIB SUPERNOVAE WITH ASYMMETRY IN CASSIOPEIA A USING LIGHT ECHOES
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Finn, Kieran; Bianco, Federica B.; Modjaz, Maryam; Liu, Yu-Qian [Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States); Rest, Armin [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
2016-10-20
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 (LEs) of Cassiopeia A (Cas A), which was a historical galactic SN IIb. We revisit the results of Rest et al., who used LEs 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 λ 5876, H α , and the Ca ii near-infrared (NIR) triplet). We confirm and improve on this measurement by reproducing the effect of the LEs in the spectra of several extragalactic SNe IIb found in the literature as well as mean SN IIb spectra recently created by Liu et al. 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 use a Monte Carlo method to measure the absorption velocities of these three features in the spectra. We then test the hypothesis that the diversity of ejecta velocities seen in SNe IIb can be explained by asphericity. We do this by comparing the range of velocities seen in the different LEs, and hence different lines of sight, of Cas A to that seen in the population of SNe IIb. We conclude that these two ranges are of the same order and thus asphericity could be enough to explain the diversity in the expansion velocity alone.
Kindlins, integrin activation and the regulation of talin recruitment to αIIbβ3.
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Bryan N Kahner
Full Text Available Talins and kindlins bind to the integrin β3 cytoplasmic tail and both are required for effective activation of integrin αIIbβ3 and resulting high-affinity ligand binding in platelets. However, binding of the talin head domain alone to β3 is sufficient to activate purified integrin αIIbβ3 in vitro. Since talin is localized to the cytoplasm of unstimulated platelets, its re-localization to the plasma membrane and to the integrin is required for activation. Here we explored the mechanism whereby kindlins function as integrin co-activators. To test whether kindlins regulate talin recruitment to plasma membranes and to αIIbβ3, full-length talin and kindlin recruitment to β3 was studied using a reconstructed CHO cell model system that recapitulates agonist-induced αIIbβ3 activation. Over-expression of kindlin-2, the endogenous kindlin isoform in CHO cells, promoted PAR1-mediated and talin-dependent ligand binding. In contrast, shRNA knockdown of kindlin-2 inhibited ligand binding. However, depletion of kindlin-2 by shRNA did not affect talin recruitment to the plasma membrane, as assessed by sub-cellular fractionation, and neither over-expression of kindlins nor depletion of kindlin-2 affected talin interaction with αIIbβ3 in living cells, as monitored by bimolecular fluorescence complementation. Furthermore, talin failed to promote kindlin-2 association with αIIbβ3 in CHO cells. In addition, purified talin and kindlin-3, the kindlin isoform expressed in platelets, failed to promote each other's binding to the β3 cytoplasmic tail in vitro. Thus, kindlins do not promote initial talin recruitment to αIIbβ3, suggesting that they co-activate integrin through a mechanism independent of recruitment.
van der Meijden, Paola E J; Feijge, Marion A H; Swieringa, Frauke; Gilio, Karen; Nergiz-Unal, Reyhan; Hamulyák, Karly; Heemskerk, Johan W M
2012-10-01
The fibrin(ogen) receptor, integrin α(IIb)β(3), has a well-established role in platelet spreading, aggregation and clot retraction. How α(IIb)β(3) contributes to platelet-dependent coagulation is less well resolved. Here, we demonstrate that the potent suppressing effect of clinically used α(IIb)β(3) blockers on tissue factor-induced thrombin generation is linked to diminished platelet Ca(2+) responses and phosphatidylserine (PS) exposure. The same blockers suppress these responses in platelets stimulated with collagen and thrombin receptor agonists, whereas added fibrinogen potentiates these responses. In platelets spreading on fibrinogen, outside-in α(IIb)β(3) signaling similarly enhances thrombin-induced Ca(2+) rises and PS exposure. These responses are reduced in α(IIb)β(3)-deficient platelets from patients with Glanzmann's thrombasthenia. Furthermore, the contribution of α(IIb)β(3) to tissue factor-induced platelet Ca(2+) rises, PS exposure and thrombin generation in plasma are fully dependent on Syk kinase activity. Tyrosine phosphorylation analysis confirms a key role of Syk activation, which is largely but not exclusively dependent on α(IIb)β(3) activation. It is concluded that the majority of tissue factor-induced procoagulant activity of platelets relies on Syk activation and ensuing Ca(2+) signal generation, and furthermore that a considerable part of Syk activation relies on α(IIb)β(3) signaling. These results hence point to a novel role of Syk in integrin-dependent thrombin generation.
D branes in background fluxes and Nielsen-Olesen instabilities
International Nuclear Information System (INIS)
Russo, Jorge G.
2016-01-01
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 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.
D branes in background fluxes and Nielsen-Olesen instabilities
Energy Technology Data Exchange (ETDEWEB)
Russo, Jorge G. [Institució Catalana de Recerca i Estudis Avançats (ICREA),Pg. Lluis Companys, 23, 08010 Barcelona (Spain); Department de Fisica Cuantica i Astrofisica and Institut de Ciències del Cosmos,Universitat de Barcelona, Martí Franquès, 1, 08028 Barcelona (Spain)
2016-06-06
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{sub 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.
Electromagnetic dipole radiation of oscillating D-branes
International Nuclear Information System (INIS)
Savvidy, G.K.
2000-01-01
I emphasize analogy between Dp-branes in string theories and solitons in gauge theories comparing their common properties and showing differences. In string theory we do not have the full set of equations which define the theory in all orders of coupling constant as it was in gauge theories, nevertheless such solutions have been found as solutions of low energy superstring effective action carrying the RR charges. The existence of dynamical RR charged extended objects in string theory has been deduced also by considering string theory with mixed boundary conditions, when type II closed superstring theory is enriched by open strings with Neumann boundary conditions on p + 1 directions and Dirichlet conditions on the remaining 9-p transverse directions. We will show that for certain excitations of the string/D3-brane system Neumann boundary conditions emerge from the Born-Infeld dynamics. Here the excitations which are coming down the string with a polarization along a direction parallel to the brane are almost completely reflected just as in the case of all-normal Dirichlet excitations considered by Callan and Maldacena, but now the end of the string moves freely on the 3-brane realizing Polchinski's open string Neumann boundary condition dynamically. In the low energy limit ω → 0, i.e. for wavelengths much larger than the string scale only a small fraction ∼ ω 4 of the energy escapes in the form of dipole radiation. The physical interpretation is that a string attached to the 3-brane manifests itself as an electric charge, and waves on the string cause the end point of the string to freely oscillate and produce e.m. dipole radiation in the asymptotic outer region. The magnitude of emitted power is in fact exactly equal to the one given by Thomson formula in electrodynamics
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.
Dynamical Formation of Horizons in Recoiling D Branes
Ellis, Jonathan Richard; Nanopoulos, Dimitri V; Ellis, John
2000-01-01
A toy calculation of string/D-particle interactions within a world-sheet approach indicates that quantum recoil effects - reflecting the gravitational back-reaction on space-time foam due to the propagation of energetic particles - induces the appearance of a microscopic event horizon, or `bubble', inside which stable matter can exist. The scattering event causes this horizon to expand, but we expect quantum effects to cause it to contract again, in a `bounce' solution. Within such `bubbles', massless matter propagates with an effective velocity that is less than the velocity of light in vacuo, which may lead to observable violations of Lorentz symmetry that may be tested experimentally. The conformal invariance conditions in the interior geometry of the bubbles select preferentially three for the number of the spatial dimensions, corresponding to a consistent formulation of the interaction of D3 branes with recoiling D particles, which are allowed to fluctuate independently only on the D3-brane hypersurface.
Gravity mediation in 6d brane-world supergravity
International Nuclear Information System (INIS)
Lee, H.M.
2005-09-01
We consider the gravity-mediated SUSY breaking within the effective theory of six-dimensional brane-world supergravity. We construct the supersymmetric bulk-brane action by Noether method and find the nontrivial moduli coupling of the brane F- and D-terms. We find that the low energy Kaehler potential is not of sequestered form, so gravity mediation may occur at tree level. In moduli stabilization with anomaly effects included, the scalar soft mass squared can be positive at tree level and it can be comparable to the anomaly mediation. (orig.)
Tachyon tube on non BPS D-branes
International Nuclear Information System (INIS)
Huang Wunghong
2004-01-01
We report our searches for a single tubular tachyonic solution of regular profile on unstable non BPS D3-branes. We first show that some extended Dirac-Born-Infeld tachyon actions in which new contributions are added to avoid the Derrick's no-go theorem still could not have a single regular tube solution. Next we use the Minahan-Zwiebach tachyon action to find the regular tube solutions with circular or elliptic cross section. With a critical electric field, the energy of the tube comes entirely from the D0 and strings, while the energy associated to the tubular D2-brane tension is vanishing. We also show that fluctuation spectrum around the tube solution does not contain tachyonic mode. The results are consistent with the identification of the tubular configuration as a BPS D2-brane. (author)
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
A review of the microscopic modeling of the 5-dim. black hole of IIB
Indian Academy of Sciences (India)
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 ...
On D-brane anti D-brane effective actions and their corrections to all orders in alpha-prime
International Nuclear Information System (INIS)
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 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 C V φ V T V T > , one has to consider the fact that scalar's vertex operator in (-1)-picture must carry the internal σ 3 Chan-Paton matrix. The symmetric trace effective action has a non-zero coupling between Dφ (1)i and Dφ (2) i while this coupling does not exist in ordinary trace effective action
International Nuclear Information System (INIS)
Sellami, Walid
2007-01-01
The aim of our study was to evaluate the immediate results and long-term intake of anti-GP IIb / IIIa inhibitors for patients with acute coronary syndrome treated with coronary angioplasty. The use of anti-GP IIb / IIIa is a valid therapeutic option in patients with acute coronary syndrome with signs of severity and for patients undergoing complex angioplasty. Adverse effects of anti-GP IIb / IIIa can be seen to encourage vigilance and careful monitoring during the administration of these molecules and perfect knowledge of their pharmacological properties for appropriate use.
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
International Nuclear Information System (INIS)
Ferrigno, Robson; Oliveira Faria, Sergio Luis Campos de
1995-01-01
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)
Invasive cervical carcinoma (stage IB-IIB): assessment with MR imaging
International Nuclear Information System (INIS)
Sironi, S.; Del Maschio, A.; Belloni, C.; Taccagni, L.
1990-01-01
In patients with cervical carcinoma the selection of the optimal therapy depends on the precise preoperative assessment of the extent of disease. Currently, decisions regarding the management of these patients are made on the basis of clinical (FIGO) staging that has 50% mean error rate. To investigate the value of MR imaging in staging patients with invasive cervical cancer, we performed 25 MR examinations on 23 patients with histologic diagnosis of cervical cancer. All patients were clinically considered as having stage IB or IIB disease and underwent radical hysterectomy, providing specimens for pathologic correlation. The overall accuracy of MR imaging in staging cervical carcinoma (stage IB-IIB) was 78.1%. MR imaging seems to be the most reliable preoperative modality for staging invasive cervical cancer
S and U-duality constraints on IIB S-matrices
International Nuclear Information System (INIS)
Chalmers, Gordon
2000-01-01
S- and U-duality dictate that graviton scattering amplitudes in IIB superstring theory be automorphic functions on the appropriate fundamental domain which describe the inequivalent vacua of (compactified) theories. A constrained functional form of graviton scattering is proposed using Eisenstein series and their generalizations compatible with: (a) two-loop supergravity, (b) genus one superstring theory, (c) the perturbative coupling dependence of the superstring, and (d) with the unitarity structure of the massless modes. The form has a perturbative truncation in the genus expansion at a given order in the derivative expansion. Comparisons between graviton scattering S-matrices and effective actions for the first quantized superstring are made at the quantum level. Possible extended finiteness properties of maximally extended quantum supergravity theories in different dimensions is implied by the perturbative truncation of the functional form of graviton scattering in IIB superstring theory
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.
International Nuclear Information System (INIS)
Volume IIB contains appendices for: flight line maps; geology maps; explanation of geologic legend; flight line/geology maps; radiometric contour maps; magnetic contour maps; geochemical factor analysis maps
Trivalent Chromium Process (TCP) as a Sealer for MIL-A-8625F Type II, IIB, and IC Anodic Coatings
National Research Council Canada - National Science Library
Matzdorf, Craig; Beck, Erin; Hilgeman, Amy; Prado, Ruben
2008-01-01
This report documents evaluations of trivalent chromium compositions (TCP) as sealers for MIL-A-8625F Type II, IIB, and IC anodic coatings conducted from March 2001 through December 2007 by Materials Engineering...
Bartl, S; Weissman, I L
1994-01-01
The major histocompatibility complex (MHC) contains a set of linked genes which encode cell surface proteins involved in the binding of small peptide antigens for their subsequent recognition by T lymphocytes. MHC proteins share structural features and the presence and location of polymorphic residues which play a role in the binding of antigens. In order to compare the structure of these molecules and gain insights into their evolution, we have isolated two MHC class IIB genes from the nurse...
Di-J/ψ Studies, Level 3 Tracking and the D0 Run IIb Upgrade
International Nuclear Information System (INIS)
Vint, Philip John
2009-01-01
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 (micro)m. 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.
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.
Hydroxyurea with Radiation Therapy of the Carcinoma of the Cervix IIA, IIB
Energy Technology Data Exchange (ETDEWEB)
Kim, Jin Hee; Youn, Seon Min; Kim, Ok Bae [Keimyung University College of Medicine, Taegu (Korea, Republic of)
1995-12-15
Purpose : To evaluate the efficacy of hydroxyurea with radiation in carcinoma of the cervix, huge exophytic or endophytic stage IIa and Iib. Materials and Methods : Sixty four patients with carcinoma of the cervix stage IIA(29 patients) with exophytic({>=}3cm in diameter) or huge endophytic mass and IIB(35 patients) treated with radiation and hydroxyurea at the Department of Radiation Oncology, Dongsan Hospital, Keimyung University, School of Medicine from Aug, 1989 to May, 1991. The maximum and mean follow up durations were 68 and 57 months respectively. The radiation therapy consisted of external irradiation to the whole pelvis(3600-5400cGy) shield (4X10 cm), and combined with intracavitary irradiation (3000-3500cGy to point A). Hydroxyurea was to be taken in a single oral dose of 1.0gm/day during radiation therapy. Results : The control rate was 89.1%. The actuarial overall five year survival rate was 78.8% for stage IIA and 72.8% for stage IIB. The overall recurrence rate was 25%(16/64). Twenty-three percent of the patients developed or greater thrombocytopenia. Grade 3 or greater GI, GU complication and anemia were not noted. There was no treatment related death noted. Conclusion : We considered that hydroxyurea and radiation therapy may improve survival rate in huge exophytic and endophytic stage IIa cervical carcinoma with acceptible morbidity.
Hydroxyurea with Radiation Therapy of the Carcinoma of the Cervix IIA, IIB
International Nuclear Information System (INIS)
Kim, Jin Hee; Youn, Seon Min; Kim, Ok Bae
1995-01-01
Purpose : To evaluate the efficacy of hydroxyurea with radiation in carcinoma of the cervix, huge exophytic or endophytic stage IIa and Iib. Materials and Methods : Sixty four patients with carcinoma of the cervix stage IIA(29 patients) with exophytic(≥3cm in diameter) or huge endophytic mass and IIB(35 patients) treated with radiation and hydroxyurea at the Department of Radiation Oncology, Dongsan Hospital, Keimyung University, School of Medicine from Aug, 1989 to May, 1991. The maximum and mean follow up durations were 68 and 57 months respectively. The radiation therapy consisted of external irradiation to the whole pelvis(3600-5400cGy) shield (4X10 cm), and combined with intracavitary irradiation (3000-3500cGy to point A). Hydroxyurea was to be taken in a single oral dose of 1.0gm/day during radiation therapy. Results : The control rate was 89.1%. The actuarial overall five year survival rate was 78.8% for stage IIA and 72.8% for stage IIB. The overall recurrence rate was 25%(16/64). Twenty-three percent of the patients developed or greater thrombocytopenia. Grade 3 or greater GI, GU complication and anemia were not noted. There was no treatment related death noted. Conclusion : We considered that hydroxyurea and radiation therapy may improve survival rate in huge exophytic and endophytic stage IIa cervical carcinoma with acceptible morbidity
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.
Gollnick, Ingo
2012-01-01
Evidence-based and guideline-conforming treatment of claudication in Fontaine stage IIb due to peripheral artery disease is basically conservative. However, many patients in Fontaine stage IIb disease are treated also treated surgically, e.g. with bypass operations or endarterectomy, or with endovascular methods (angioplasty and variations thereof ). The present study compares patient satisfaction with these three therapy modalities. Methods: 666 patients with Fontaine IIb cla...
Flow and transport at the Las Cruces trench site: Experiment IIb
International Nuclear Information System (INIS)
Vinson, J.; Hills, R.G.; Wierenga, P.J.; Young, M.H.
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
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.
On running couplings in gauge theories from type-IIB supergravity
Kehagias, A A
1999-01-01
We construct an explicit solution of type-IIB supergravity describing the strong coupling regime of a non-supersymmetric gauge theory. The latter has a running coupling with an ultraviolet stable fixed point corresponding to the N=4 SU(N) super-Yang-Mills theory at large N. The running coupling has a power law behaviour, argued to be universal, that is consistent with holography. Around the critical point, our solution defines an asymptotic expansion for the gauge coupling beta-function. We also calculate the first correction to the Coulombic quark-antiquark potential.
Precision holography for N={2}^{\\ast } on S 4 from type IIB supergravity
Bobev, Nikolay; Gautason, Friðrik Freyr; van Muiden, Jesse
2018-04-01
We find a new supersymmetric solution of type IIB supergravity which is holographically dual to the planar limit of the four-dimensional N={2}^{\\ast } supersymmetric Yang-Mills theory on S 4. We study a probe fundamental string in this background which is dual to a supersymmetric Wilson loop in the N={2}^{\\ast } theory. Using holography we calculate the expectation value of this line operator to leading order in the 't Hooft coupling. The result is a non-trivial function of the mass parameter of the N={2}^{\\ast } theory that precisely matches the result from supersymmetric localization.
[Complications of surgical stage of treatment in patients with cancer of cervix uteri stage IIB].
Kryzhanivs'ka, A Ie
2013-11-01
The results of treatment of 127 patients, suffering cervix uteri cancer stage IIB in period of 1998 - 2012 yrs, were analyzed. Complications of surgical stage of the combined treatment have had occurred in 40.9% patients, including 40.5% patients, to whom neoadjuvant chemotherapy was conducted and in 41.5%--radiation therapy (RTH). The main postoperative complications--retroperitoneal lymphatic cysts--were revealed in 35.4% patients. The factors, raising the risk of postoperative complications occurrence, are following: the primary tumor spreading, metastatic affection of lymphatic nodes of pelvic cavity, preoperative conduction of RTH or chemotherapy.
Universal properties of type IIB and F-theory flux compactifications at large complex structure
International Nuclear Information System (INIS)
Marsh, M.C. David; Sousa, Kepa
2016-01-01
We consider flux compactifications of type IIB string theory and F-theory in which the respective superpotentials at large complex structure are dominated by cubic or quartic terms in the complex structure moduli. In this limit, the low-energy effective theory exhibits universal properties that are insensitive to the details of the compactification manifold or the flux configuration. Focussing on the complex structure and axio-dilaton sector, we show that there are no vacua in this region and the spectrum of the Hessian matrix is highly peaked and consists only of three distinct eigenvalues (0, 2m 3/2 2 and 8m 3/2 2 ), independently of the number of moduli. We briefly comment on how the inclusion of Kähler moduli affect these findings. Our results generalise those of Brodie & Marsh http://dx.doi.org/10.1007/JHEP01(2016)037, in which these universal properties were found in a subspace of the large complex structure limit of type IIB compactifications.
Bartl, S; Weissman, I L
1994-01-04
The major histocompatibility complex (MHC) contains a set of linked genes which encode cell surface proteins involved in the binding of small peptide antigens for their subsequent recognition by T lymphocytes. MHC proteins share structural features and the presence and location of polymorphic residues which play a role in the binding of antigens. In order to compare the structure of these molecules and gain insights into their evolution, we have isolated two MHC class IIB genes from the nurse shark, Ginglymostoma cirratum. Two clones, most probably alleles, encode proteins which differ by 13 amino acids located in the putative antigen-binding cleft. The protein structure and the location of polymorphic residues are similar to their mammalian counterparts. Although these genes appear to encode a typical MHC protein, no T-cell-mediated responses have been demonstrated in cartilaginous fish. The nurse shark represents the most phylogenetically primitive organism in which both class IIA [Kasahara, M., Vazquez, M., Sato, K., McKinney, E.C. & Flajnik, M.F. (1992) Proc. Natl. Acad. Sci USA 89, 6688-6692] and class IIB genes, presumably encoding the alpha/beta heterodimer, have been isolated.
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.)
Ultraviolet Detection of the Binary Companion to the Type IIb SN 2001ig
Ryder, Stuart D.; Van Dyk, Schuyler D.; Fox, Ori D.; Zapartas, Emmanouil; de Mink, Selma E.; Smith, Nathan; Brunsden, Emily; Azalee Bostroem, K.; Filippenko, Alexei V.; Shivvers, Isaac; Zheng, WeiKang
2018-03-01
We present HST/WFC3 ultraviolet imaging in the F275W and F336W bands of the Type IIb SN 2001ig at an age of more than 14 years. A clear point source is detected at the site of the explosion, with m F275W = 25.39 ± 0.10 and m F336W = 25.88 ± 0.13 mag. Despite weak constraints on both the distance to the host galaxy NGC 7424 and the line-of-sight reddening to the supernova, this source matches the characteristics of an early B-type main-sequence star with 19,000 GMOS optical spectrum at an age of 6 years reveals a narrow He II λ4686 emission line, indicative of continuing interaction with a dense circumstellar medium at large radii from the progenitor. We review our findings on SN 2001ig in the context of binary evolution channels for stripped-envelope supernovae. Owing to the uncrowded nature of its environment in the ultraviolet, this study of SN 2001ig represents one of the cleanest detections to date of a surviving binary companion to a Type IIb supernova.
On zero-point energy, stability and Hagedorn behavior of Type IIB strings on pp-waves
International Nuclear Information System (INIS)
Bigazzi, F.; Cotrone, A.L.
2003-06-01
Type IIB strings on many pp-wave backgrounds, supported either by 5-form or 3-form fluxes, have negative light-cone zero-point energy. This raises the question of their stability and poses possible problems in the definition of their thermodynamic properties. After having pointed out the correct way of calculating the zero-point energy, an issue not fully discussed in literature, we show that these Type IIB strings are classically stable and have well defined thermal properties, exhibiting a Hagedorn behavior. (author)
Directory of Open Access Journals (Sweden)
Yi-Hung Kuo
2018-01-01
Conclusion: Different predictors of DFS were observed in stage IIa and IIb colon cancer; adjuvant chemotherapy could provide a survival benefit for patients with stage IIb colon cancer who have one of the four factors that were studied in our hospital-based analysis.
Nonperturbative type IIB model building in the F-theory framework
International Nuclear Information System (INIS)
Jurke, Benjamin Helmut Friedrich
2011-01-01
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
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
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
Pierce, M W; Remold-O'Donnell, E; Todd, R F; Arnaout, M A
1986-12-12
Mo1 and gp160-gp93 are two surface membrane glycoprotein heterodimers present on granulocytes and monocytes derived from humans and guinea pigs, respectively. We purified both antigens and found that their alpha subunits had identical N-termini which were significantly homologous to the alpha subunit of the human adhesion platelet glycoprotein IIb/IIIa.
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.
On R4 threshold corrections in type IIB string theory and (p,q)-string instantons
International Nuclear Information System (INIS)
Kiritsis, E.; Pioline, B.
1997-01-01
We obtain the exact non-perturbative thresholds of R 4 terms in type IIB string theory compactified to eight and seven dimensions. These thresholds are given by the perturbative tree-level and one-loop results together with the contribution of the D-instantons and of the (p,q)-string instantons. The invariance under U-duality is made manifest by rewriting the sum as a non-holomorphic-invariant modular function of the corresponding discrete U-duality group. In the eight-dimensional case, the threshold is the sum of an order-1 Eisenstein series for SL(2,Z) and an order-3/2 Eisenstein series for SL(3,Z). The seven-dimensional result is given by the order-3/2 Eisenstein series for SL(5,Z). We also conjecture formulae for the non-perturbative thresholds in lower-dimensional compactifications and discuss the relation with M-theory. (orig.)
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.
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.
On Type IIB moduli stabilization and N=4,8 supergravities
Energy Technology Data Exchange (ETDEWEB)
Aldazabal, Gerardo [Centro Atomico Bariloche, Instituto Balseiro (CNEA-UNC) and CONICET, 8400 S.C. de Bariloche (Argentina); Marques, Diego [Institut de Physique Theorique, CEA/ Saclay, 91191 Gif-sur-Yvette Cedex (France); Nunez, Carmen, E-mail: carmen@iafe.uba.a [Instituto de Astronomia y Fisica del Espacio (CONICET-UBA) and Departamento de Fisica, FCEN, Universidad de Buenos Aires, C.C. 67 - Suc. 28, 1428 Buenos Aires (Argentina); Rosabal, Jose A. [Centro Atomico Bariloche, Instituto Balseiro (CNEA-UNC) and CONICET, 8400 S.C. de Bariloche (Argentina)
2011-08-01
We analyze D=4 compactifications of Type IIB theory with generic, geometric and non-geometric, dual fluxes turned on. In particular, we study N=1 toroidal orbifold compactifications that admit an embedding of the untwisted sector into gauged N=4,8 supergravities. Truncations, spontaneous breaking of supersymmetry and the inclusion of sources are discussed. The algebraic identities satisfied by the supergravity gaugings are used to implement the full set of consistency constraints on the background fluxes. This allows to perform a generic study of N=1 vacua and identify large regions of the parameter space that do not admit complete moduli stabilization. Illustrative examples of AdS and Minkowski vacua are presented.
PKL-tests, test series IIB (end of blowdown). Vol. 2
International Nuclear Information System (INIS)
Umminger, K.; Mandl, R.; Nopper, H.; Siemens AG Unternehmensbereich KWU, Erlangen
1987-01-01
As part of the federally subsidized research project 1500 287/A0, the system behavior of a 1300 MWe pressurized water reactor (PWR) was investigated during the depressurization phase (end-of-blowdown, EOB), as well as during the refill and reflood phases of a loss of coolant accident involving a large break in the reactor coolant loop. Appropriate modifications to the system and supplementary instrumentation have made it possible to simulate the EOB (as of 26 bar), the refill phase and reflood phase in sequence. This report includes a detailed description of the instrumentation and the data acquisition system used in Test Series PKL IIB. (orig.) With 6 refs., 2 tabs., 60 figs [de
Measurements on irradiated L1 sensor prototypes for the D0 Run IIb silicon detector project
International Nuclear Information System (INIS)
Ahsan, M.; Bolton, T.; Carnes, K.; Demarteau, M.; Demina, R.; Gray, T.; Korjenevski, S.; Lehner, F.; Lipton, R.; Mao, H.S.; McCarthy, R.
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 14 p/cm 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.
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.
Duan, Hao; Cai, Yan; Sun, Xiaojiang
2012-01-01
The role of genetic risk factors in ischemic stroke is unclear. Platelet glycoprotein IIb/IIIa (GpIIb-IIIa) has been implicated in the pathogenesis of ischemic stroke. We sought to evaluate the relationship between the GpIIb/IIIa complex gene polymorphism and ischemic stroke. We investigated the association of the GpIIb/IIIa complex gene polymorphism with stroke risk in 306 patients with acute ischemic stroke and 266 control subjects by determining the GpIIb and GpIIIa genotype from leukocyte DNA by polymerase chain reaction (PCR) followed by FokI and ScrFI digestion, respectively. Compared with controls, more patients presented with coronary heart disease, hypertension, smoking history, and diabetes. In addition, the patients had higher levels of cholesterol and glucose compared with the control subjects. All donors in the GpIIIa (n=572) group expressed the GpIIIa PlA1 (HPA-1 aa) phenotype. There were no significant differences between the HPA-3 genotype (GpIIb) patient distribution (aa=39.9%, ab=41.4%, bb=28.7%) and healthy control subjects (aa=36.1%, ab=35.0%, bb=28.9%) (P=0.580). Among study participants ischemic stroke >2-fold (P=0.008). The GpIIb Ile/Ser843 gene polymorphism is associated with ischemic stroke among young and middle-aged adults (ischemic stroke.
Mann, Howard; London, Alex John; Mann, Jeffrey
2005-01-01
Enhanced Supression of the Platelet IIb/IIIa Receptor with Integrilin Trial (ESPRIT) was a multicenter randomized controlled clinical trial in which participants were randomized between eptifibatide and placebo. A "clinical hold" was initially placed on the trial by the US Food and Drug Administration (FDA), which was concerned about the placebo-only control arm. The hold was lifted after additional information concerning the use of platelet glycoprotein IIb/IIIa inhibitors in clinical practice, derived from a survey of interventional cardiologists, was provided. The trial's principal investigator and colleagues have described how these issues were resolved, and advance a claim of equipoise for the trial. In this critical appraisal we examine the information and arguments proffered in support of the trial design and conclude that they evidence a misunderstanding of equipoise. We believe that a placebo-only control arm was not justified by the information provided by the trialists.
AdS3 xw (S3 x S3 x S1) solutions of type IIB string theory
International Nuclear Information System (INIS)
Donos, Aristomenis; Gauntlett, Jerome P.; Imperial College, London; Sparks, James
2008-10-01
We analyse a recently constructed class of local solutions of type IIB supergravity that consist of a warped product of AdS 3 with a sevendimensional internal space. In one duality frame the only other nonvanishing fields are the NS three-form and the dilaton. We analyse in detail how these local solutions can be extended to globally well-defined solutions of type IIB string theory, with the internal space having topology S 3 x S 3 x S 1 and with properly quantised three-form flux. We show that many of the dual (0,2) SCFTs are exactly marginal deformations of the (0,2) SCFTs whose holographic duals are warped products of AdS 3 with seven-dimensional manifolds of topology S 3 x S 2 x T 2 . (orig.)
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.
K.M. Akkerhuis (Martijn); P. Théroux (Pierre); R.M. Califf (Robert); E.J. Topol (Eric); M.L. Simoons (Maarten); H. Boersma (Eric)
1999-01-01
textabstractBACKGROUND: Glycoprotein (GP) IIb/IIIa receptor blockers prevent life-threatening cardiac complications in patients with acute coronary syndromes without ST-segment elevation and protect against thrombotic complications associated with percutaneous coronary
Shanley, Daniel K; Kiely, Patrick A; Golla, Kalyan; Allen, Seamus; Martin, Kenneth; O'Riordan, Ronan T; Ball, Melanie; Aplin, John D; Singer, Bernhard B; Caplice, Noel; Moran, Niamh; Moore, Tom
2013-01-01
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.
Realizing three generations of the Standard Model fermions in the type IIB matrix model
International Nuclear Information System (INIS)
Aoki, Hajime; Nishimura, Jun; Tsuchiya, Asato
2014-01-01
We discuss how the Standard Model particles appear from the type IIB matrix model, which is considered to be a nonperturbative formulation of superstring theory. In particular, we are concerned with a constructive definition of the theory, in which we start with finite-N matrices and take the large-N limit afterwards. In that case, it was pointed out recently that realizing chiral fermions in the model is more difficult than it had been thought from formal arguments at N=∞ and that introduction of a matrix version of the warp factor is necessary. Based on this new insight, we show that two generations of the Standard Model fermions can be realized by considering a rather generic configuration of fuzzy S"2 and fuzzy S"2×S"2 in the extra dimensions. We also show that three generations can be obtained by squashing one of the S"2’s that appear in the configuration. Chiral fermions appear at the intersections of the fuzzy manifolds with nontrivial Yukawa couplings to the Higgs field, which can be calculated from the overlap of their wave functions.
Universality and the dynamical space-time dimensionality in the Lorentzian type IIB matrix model
Energy Technology Data Exchange (ETDEWEB)
Ito, Yuta [KEK Theory Center, High Energy Accelerator Research Organization,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Nishimura, Jun [KEK Theory Center, High Energy Accelerator Research Organization,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Graduate University for Advanced Studies (SOKENDAI),1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Tsuchiya, Asato [Department of Physics, Shizuoka University,836 Ohya, Suruga-ku, Shizuoka 422-8529 (Japan)
2017-03-27
The type IIB matrix model is one of the most promising candidates for a nonperturbative formulation of superstring theory. In particular, its Lorentzian version was shown to exhibit an interesting real-time dynamics such as the spontaneous breaking of the 9-dimensional rotational symmetry to the 3-dimensional one. This result, however, was obtained after regularizing the original matrix integration by introducing “infrared” cutoffs on the quadratic moments of the Hermitian matrices. In this paper, we generalize the form of the cutoffs in such a way that it involves an arbitrary power (2p) of the matrices. By performing Monte Carlo simulation of a simplified model, we find that the results become independent of p and hence universal for p≳1.3. For p as large as 2.0, however, we find that large-N scaling behaviors do not show up, and we cannot take a sensible large-N limit. Thus we find that there is a certain range of p in which a universal large-N limit can be taken. Within this range of p, the dynamical space-time dimensionality turns out to be (3+1), while for p=2.0, where we cannot take a sensible large-N limit, we observe a (5+1)d structure.
A peptide affinity column for the identification of integrin alpha IIb-binding proteins.
Daxecker, Heide; Raab, Markus; Bernard, Elise; Devocelle, Marc; Treumann, Achim; Moran, Niamh
2008-03-01
To understand the regulation of integrin alpha(IIb)beta(3), a critical platelet adhesion molecule, we have developed a peptide affinity chromatography method using the known integrin regulatory motif, LAMWKVGFFKR. Using standard Fmoc chemistry, this peptide was synthesized onto a Toyopearl AF-Amino-650 M resin on a 6-aminohexanoic acid (Ahx) linker. Peptide density was controlled by acetylation of 83% of the Ahx amino groups. Four recombinant human proteins (CIB1, PP1, ICln and RN181), previously identified as binding to this integrin regulatory motif, were specifically retained by the column containing the integrin peptide but not by a column presenting an irrelevant peptide. Hemoglobin, creatine kinase, bovine serum albumin, fibrinogen and alpha-tubulin failed to bind under the chosen conditions. Immunodetection methods confirmed the binding of endogenous platelet proteins, including CIB1, PP1, ICln RN181, AUP-1 and beta3-integrin, from a detergent-free platelet lysate. Thus, we describe a reproducible method that facilitates the reliable extraction of specific integrin-binding proteins from complex biological matrices. This methodology may enable the sensitive and specific identification of proteins that interact with linear, membrane-proximal peptide motifs such as the integrin regulatory motif LAMWKVGFFKR.
Lordier, Larissa; Bluteau, Dominique; Jalil, Abdelali; Legrand, Céline; Pan, Jiajia; Rameau, Philippe; Jouni, Dima; Bluteau, Olivier; Mercher, Thomas; Leon, Catherine; Gachet, Christian; Debili, Najet; Vainchenker, William; Raslova, Hana; Chang, Yunhua
2012-03-06
Megakaryocytes are unique mammalian cells that undergo polyploidization (endomitosis) during differentiation, leading to an increase in cell size and protein production that precedes platelet production. Recent evidence demonstrates that endomitosis is a consequence of a late failure in cytokinesis associated with a contractile ring defect. Here we show that the non-muscle myosin IIB heavy chain (MYH10) is expressed in immature megakaryocytes and specifically localizes in the contractile ring. MYH10 downmodulation by short hairpin RNA increases polyploidization by inhibiting the return of 4N cells to 2N, but other regulators, such as of the G1/S transition, might regulate further polyploidization of the 4N cells. Conversely, re-expression of MYH10 in the megakaryocytes prevents polyploidization and the transition of 2N to 4N cells. During polyploidization, MYH10 expression is repressed by the major megakaryocyte transcription factor RUNX1. Thus, RUNX1-mediated silencing of MYH10 is required for the switch from mitosis to endomitosis, linking polyploidization with megakaryocyte differentiation.
Synthesis and characterization of p-type boron-doped IIb diamond large single crystals
International Nuclear Information System (INIS)
Li Shang-Sheng; Li Xiao-Lei; Su Tai-Chao; Jia Xiao-Peng; Ma Hong-An; Huang Guo-Feng; Li Yong
2011-01-01
High-quality p-type boron-doped IIb diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond. (cross-disciplinary physics and related areas of science and technology)
The spectra of type IIB flux compactifications at large complex structure
International Nuclear Information System (INIS)
Brodie, Callum; Marsh, M.C. David
2016-01-01
We compute the spectra of the Hessian matrix, H, and the matrix 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 H and 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 is strongly linearly correlated with the value of the superpotential over almost the entire moduli space, with particularly strong correlations arising for g s <1. We contrast these results with the expectations from the much-used continuous flux approximation, and comment on the applicability of Random Matrix Theory to the statistical modelling of the string theory landscape.
Chen, Jianshun; Fang, Chun; Zhu, Ningyu; Lv, Yonghui; Cheng, Changyong; Bei, Yijiang; Zheng, Tianlun; Fang, Weihuan
2012-05-01
Listeria monocytogenes is an important foodborne pathogen that comprises four genetic lineages: I, II, III, and IV. Of these, lineage II is frequently recovered from foods and environments and responsible for the increasing incidence of human listeriosis. In this study, the phylogenetic structure of lineage II was determined through sequencing analysis of the ascB-dapE internalin cluster. Fifteen sequence types proposed by multilocus sequence typing based on nine housekeeping genes were grouped into three distinct sublineages, IIA, IIB, and IIC. Organization of the ascBdapE internalin cluster could serve as a molecular marker for these sublineages, with inlGHE, inlGC2DE, and inlC2DE for IIA, IIB, and IIC, respectively. These sublineages displayed specific genetic and phenotypic characteristics. IIA and IIC showed a higher frequency of recombination (rho/theta). However, recombination events had greater effect (r/m) on IIB, leading to its high nucleotide diversity. Moreover, IIA and IIB harbored a wider range of internalin and stress-response genes, and possessed higher nisin tolerance, whereas IIC contained the largest portion of low-virulent strains owing to premature stop codons in inlA. The results of this study indicate that IIA, IIB, and IIC might occupy different ecological niches, and IIB might have a better adaptation to a broad range of environmental niches.
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
Goat activin receptor type IIB knockdown by muscle specific promoter driven artificial microRNAs.
Patel, Amrutlal K; Shah, Ravi K; Patel, Utsav A; Tripathi, Ajai K; Joshi, Chaitanya G
2014-10-10
Activin receptor type IIB (ACVR2B) is a transmembrane receptor which mediates signaling of TGF beta superfamily ligands known to function in regulation of muscle mass, embryonic development and reproduction. ACVR2B antagonism has shown to enhance the muscle growth in several disease and transgenic models. Here, we show ACVR2B knockdown by RNA interference using muscle creatine kinase (MCK) promoter driven artificial microRNAs (amiRNAs). Among the various promoter elements tested, the ∼1.26 kb MCK promoter region showed maximum transcriptional activity in goat myoblasts cells. We observed up to 20% silencing in non-myogenic 293T cells and up to 32% silencing in myogenic goat myoblasts by MCK directed amiRNAs by transient transfection. Goat myoblasts stably integrated with MCK directed amiRNAs showed merely 8% silencing in proliferating myoblasts which was increased to 34% upon induction of differentiation at transcript level whereas up to 57% silencing at protein level. Knockdown of ACVR2B by 5'-UTR derived amiRNAs resulted in decreased SMAD2/3 signaling, increased expression of myogenic regulatory factors (MRFs) and enhanced proliferation and differentiation of myoblasts. Unexpectedly, knockdown of ACVR2B by 3'-UTR derived amiRNAs resulted in increased SMAD2/3 signaling, reduced expression of MRFs and suppression of myogenesis. Our study offers muscle specific knockdown of ACVR2B as a potential strategy to enhance muscle mass in the farm animal species. Copyright © 2014 Elsevier B.V. All rights reserved.
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.
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.
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.
Analysis of Radiotherapy Associated Factors in Stage IIb Carcinoma of Uterine Cervix
International Nuclear Information System (INIS)
Moon, Chang Woo; Jeung, Tae Sig; Yum, Ha Yong
1990-01-01
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
External cobalt 60 irradiation alone for stage IIB carcinoma of the uterine cervix
International Nuclear Information System (INIS)
Lei, Z.Z.; He, F.Z.
1989-01-01
From 1964 to 1980, 97 patients with Stage IIb carcinoma of cervix uteri were treated by external 60Co irradiation alone. Of these 97 patients, 94 (96.9%) had squamous cell carcinoma. The parametrial extension of the lesion almost reached the pelvic wall in 73.2% and vaginal extension reached to the upper half of vaginal in 24.7% of the patients. A tumor dose of 60 Gy was given to the whole pelvis by a four field technic (opposing parallel AP and lateral portals) in 6-8 weeks. A booster dose of 10 Gy was delivered to the cervix by a pair of reduced opposing parallel AP portals or a perineal portal in a week. The doses delivered were equivalent to the Time-Dose-Fractionation (TDF) value of 110-130 at the center of pelvis and 90-110 in the whole pelvis. The 5-year survival rate for all 97 patients was 56.7%. It was 59.8% when those who died of other diseases were excluded. The prognosis of patients without residual tumor on the cervix and/or vagina was better than that with residual tumor (p less than 0.01). Thirty-seven patients died of cancer (23 died of recurrence, 8 of distant metastases, 2 of both, and 4 were lost before the fifth year). Of these 37 patients, 97.3% died within 3 years after initial treatment. During the radiation treatment, reactions were moderate. Late complications included 19 (19.6%) with mild cystitis and 16 (16.5%) with mild proctitis, 2 (2.7%) developed recto-vaginal fistula. These results were slightly poorer than those using intracavitary and external irradiation or the combination of preoperative irradiation plus surgery. Yet, for patients with extensions nearing the pelvic wall or with contra-indications to surgery or intracavitary radiotherapy, external irradiation alone is still of value
Pandorf, Clay E; Jiang, Weihua; Qin, Anqi X; Bodell, Paul W; Baldwin, Kenneth M; Haddad, Fadia
2012-04-01
Postnatal development of fast skeletal muscle is characterized by a transition in expression of myosin heavy chain (MHC) isoforms, from primarily neonatal MHC at birth to primarily IIb MHC in adults, in a tightly coordinated manner. These isoforms are encoded by distinct genes, which are separated by ∼17 kb on rat chromosome 10. The neonatal-to-IIb MHC transition is inhibited by a hypothyroid state. We examined RNA products [mRNA, pre-mRNA, and natural antisense transcript (NAT)] of developmental and adult-expressed MHC genes (embryonic, neonatal, I, IIa, IIx, and IIb) at 2, 10, 20, and 40 days after birth in normal and thyroid-deficient rat neonates treated with propylthiouracil. We found that a long noncoding antisense-oriented RNA transcript, termed bII NAT, is transcribed from a site within the IIb-Neo intergenic region and across most of the IIb MHC gene. NATs have previously been shown to mediate transcriptional repression of sense-oriented counterparts. The bII NAT is transcriptionally regulated during postnatal development and in response to hypothyroidism. Evidence for a regulatory mechanism is suggested by an inverse relationship between IIb MHC and bII NAT in normal and hypothyroid-treated muscle. Neonatal MHC transcription is coordinately expressed with bII NAT. A comparative phylogenetic analysis also suggests that bII NAT-mediated regulation has been a conserved trait of placental mammals for most of the eutherian evolutionary history. The evidence in support of the regulatory model implicates long noncoding antisense RNA as a mechanism to coordinate the transition between neonatal and IIb MHC during postnatal development.
On the non-existence of totally localised intersections of D3/D5 branes in type IIB SUGRA
Energy Technology Data Exchange (ETDEWEB)
Patino, Leonardo [Department of Mathematical Sciences, University of Durham, Durham, DH1 3LE (United Kingdom); Smith, Douglas [Department of Mathematical Sciences, University of Durham, Durham, DH1 3LE (United Kingdom)
2005-04-01
In the present paper we study the most general configuration of intersecting D3/D5 branes in type IIB supergravity satisfying Poincare invariance in the directions common to the branes and SO(3) symmetry in the totally perpendicular directions. The form of these configurations is greatly restricted by the Killing spinor equations and the equations of motion, which among other things, force the Ramond-Ramond scalar to be zero and do not permit the existence of totally localised intersections of this kind.
On the non-existence of totally localised intersections of D3/D5 branes in type IIB SUGRA
International Nuclear Information System (INIS)
Patino, Leonardo; Smith, Douglas
2005-01-01
In the present paper we study the most general configuration of intersecting D3/D5 branes in type IIB supergravity satisfying Poincare invariance in the directions common to the branes and SO(3) symmetry in the totally perpendicular directions. The form of these configurations is greatly restricted by the Killing spinor equations and the equations of motion, which among other things, force the Ramond-Ramond scalar to be zero and do not permit the existence of totally localised intersections of this kind
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 dyslipidemia who were aged dyslipidemia who were aged <75 years. © 2013 Japan Geriatrics Society.
Trans and surface membrane bound zervamicin IIB: 13C-MAOSS-NMR at high spinning speed
International Nuclear Information System (INIS)
Raap, J.; Hollander, J.; Ovchinnikova, T. V.; Swischeva, N. V.; Skladnev, D.; Kiihne, S.
2006-01-01
Interactions between 15 N-labelled peptides or proteins and lipids can be investigated using membranes aligned on a thin polymer film, which is rolled into a cylinder and inserted into the MAS-NMR rotor. This can be spun at high speed, which is often useful at high field strengths. Unfortunately, substrate films like commercially available polycarbonate or PEEK produce severe overlap with peptide and protein signals in 13 C-MAOSS NMR spectra. We show that a simple house hold foil support allows clear observation of the carbonyl, aromatic and C α signals of peptides and proteins as well as the ester carbonyl and choline signals of phosphocholine lipids. The utility of the new substrate is validated in applications to the membrane active peptide zervamicin IIB. The stability and macroscopic ordering of thin PC10 bilayers was compared with that of thicker POPC bilayers, both supported on the household foil. Sidebands in the 31 P-spectra showed a high degree of alignment of both the supported POPC and PC10 lipid molecules. Compared with POPC, the PC10 lipids are slightly more disordered, most likely due to the increased mobilities of the shorter lipid molecules. This mobility prevents PC10 from forming stable vesicles for MAS studies. The 13 C-peptide peaks were selectively detected in a 13 C-detected 1 H-spin diffusion experiment. Qualitative analysis of build-up curves obtained for different mixing times allowed the transmembrane peptide in PC10 to be distinguished from the surface bound topology in POPC. The 13 C-MAOSS results thus independently confirms previous findings from 15 N spectroscopy [Bechinger, B., Skladnev, D.A., Ogrel, A., Li, X., Rogozhkina, E.V., Ovchinnikova, T.V., O'Neil, J.D.J. and Raap, J. (2001) Biochemistry, 40, 9428-9437]. In summary, application of house hold foil opens the possibility of measuring high resolution 13 C-NMR spectra of peptides and proteins in well ordered membranes, which are required to determine the secondary and
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
Brooks, Frank J; Grigsby, Perry W
2013-12-23
Many types of cancer are located and assessed via positron emission tomography (PET) using the 18F-fluorodeoxyglucose (FDG) radiotracer of glucose uptake. There is rapidly increasing interest in exploiting the intra-tumor heterogeneity observed in these FDG-PET images as an indicator of disease outcome. If this image heterogeneity is of genuine prognostic value, then it either correlates to known prognostic factors, such as tumor stage, or it indicates some as yet unknown tumor quality. Therefore, the first step in demonstrating the clinical usefulness of image heterogeneity is to explore the dependence of image heterogeneity metrics upon established prognostic indicators and other clinically interesting factors. If it is shown that image heterogeneity is merely a surrogate for other important tumor properties or variations in patient populations, then the theoretical value of quantified biological heterogeneity may not yet translate into the clinic given current imaging technology. We explore the relation between pelvic lymph node status at diagnosis and the visually evident uptake heterogeneity often observed in 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) images of cervical carcinomas. We retrospectively studied the FDG-PET images of 47 node negative and 38 node positive patients, each having FIGO stage IIb tumors with squamous cell histology. Imaged tumors were segmented using 40% of the maximum tumor uptake as the tumor-defining threshold and then converted into sets of three-dimensional coordinates. We employed the sphericity, extent, Shannon entropy (S) and the accrued deviation from smoothest gradients (ζ) as image heterogeneity metrics. We analyze these metrics within tumor volume strata via: the Kolmogorov-Smirnov test, principal component analysis and contingency tables. We found no statistically significant difference between the positive and negative lymph node groups for any one metric or plausible combinations thereof. Additionally
International Nuclear Information System (INIS)
Brooks, Frank J; Grigsby, Perry W
2013-01-01
Many types of cancer are located and assessed via positron emission tomography (PET) using the 18F-fluorodeoxyglucose (FDG) radiotracer of glucose uptake. There is rapidly increasing interest in exploiting the intra-tumor heterogeneity observed in these FDG-PET images as an indicator of disease outcome. If this image heterogeneity is of genuine prognostic value, then it either correlates to known prognostic factors, such as tumor stage, or it indicates some as yet unknown tumor quality. Therefore, the first step in demonstrating the clinical usefulness of image heterogeneity is to explore the dependence of image heterogeneity metrics upon established prognostic indicators and other clinically interesting factors. If it is shown that image heterogeneity is merely a surrogate for other important tumor properties or variations in patient populations, then the theoretical value of quantified biological heterogeneity may not yet translate into the clinic given current imaging technology. We explore the relation between pelvic lymph node status at diagnosis and the visually evident uptake heterogeneity often observed in 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) images of cervical carcinomas. We retrospectively studied the FDG-PET images of 47 node negative and 38 node positive patients, each having FIGO stage IIb tumors with squamous cell histology. Imaged tumors were segmented using 40% of the maximum tumor uptake as the tumor-defining threshold and then converted into sets of three-dimensional coordinates. We employed the sphericity, extent, Shannon entropy (S) and the accrued deviation from smoothest gradients (ζ) as image heterogeneity metrics. We analyze these metrics within tumor volume strata via: the Kolmogorov-Smirnov test, principal component analysis and contingency tables. We found no statistically significant difference between the positive and negative lymph node groups for any one metric or plausible combinations thereof. Additionally
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.
Cantor, Warren J; Madan, Mina; O'Shea, J Conor; Chisholm, Robert J; Lui, Henry K; Cohen, David J; Feldman, Robert L; Green, Robert; Hellkamp, Anne S; Kitt, Michael M; Tcheng, James E
2005-07-01
Glycoprotein (GP) IIb/IIIa inhibitors are often used as a rescue or bailout therapy to manage complications arising during percutaneous coronary intervention, rather than as prophylactic treatment. We sought to identify the characteristics and outcomes of patients requiring bailout treatment. The ESPRIT trial randomized 2,064 patients to receive eptifibatide or placebo starting immediately before percutaneous coronary intervention (PCI). Bailout therapy was used in 77 patients: 43 (4.2%) randomized to placebo and 34 (3.3%) to eptifibatide (p = 0.3). Bailout therapy for thrombosis was used more often in the placebo group (2.1% versus 1.0%; p = 0.03). Multivariable predictors of bailout included a greater than or equal to 90% stenosis, or visible thrombus on the baseline angiogram, and no aspirin pre-treatment before PCI. However, overall the model predicted bailout poorly (c-index = 0.64). The need for bailout cannot be reliably predicted using baseline characteristics. Patients experiencing complications have poor clinical outcomes despite bailout use of GP IIb/IIIa inhibitors.
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.
Soliman, Wael; Wang, Liru; Bhattacharjee, Subir; Kaur, Kamaljit
2011-04-14
Class IIb bacteriocins are ribosomally synthesized antimicrobial peptides comprising two different peptides synergistically acting in equal amounts for optimal potency. In this study, we demonstrate for the first time potent (nanomolar) antimicrobial activity of a representative class IIb bacteriocin, plantaricin S (Pls), against four pathogenic gram-positive bacteria, including Listeria monocytogenes. The structure-activity relationships for Pls were studied using activity assays, circular dichroism (CD), and molecular dynamics (MD) simulations. The two Pls peptides and five Pls derived fragments were synthesized. The CD spectra of the Pls and selected fragments revealed helical conformations in aqueous 2,2,2-trifluoroethanol. The MD simulations showed that when the two Pls peptides are in antiparallel orientation, the helical regions interact and align, mediated by strong attraction between conserved GxxxG/AxxxA motifs. The results strongly correlate with the antimicrobial activity suggesting that helix-helix alignment of the two Pls peptides and interaction between the conserved motifs are crucial for interaction with the target cell membrane.
The effects of age on treatment and outcomes in women with stages IB1-IIB cervical cancer.
Roque, Dario R; Cronin, Beth; Robison, Katina; Lopes, Vrishali; Rizack, Tina; Dizon, Don S
2013-10-01
Age may affect the treatment choice and subsequent outcome in elderly patients with cervical cancer. Given the potential for cure with either surgery or chemoradiation in early stage disease, we aimed to determine whether a patient's age influenced treatment received and the ensuing outcome. We identified 303 patients with stages IB1-IIB cervical carcinoma treated at our institution between 2000 and 2010, who were divided into two groups based on age at time of diagnosis: stage at presentation, and grade. Women ≥ 65 years of age were less likely to receive primary surgical management (p=0.03). Age did not influence disease-specific or all-cause mortality. However, women over 65 years who underwent primary surgery were at significantly increased risk of all-cause mortality compared to younger women (HR 6.53, 95% CI: 2.57-16.6). Age appears to influence treatment received by patients with stages IB1-IIB cervical cancer. Although there was no difference in cancer-specific mortality stratified by type of treatment received, surgery was associated with a 6.5-fold increased risk of all-cause mortality among women 65 years or over. © 2013.
Phase IIA and IIB experiments of JAERI/U.S.DOE collaborative program on fusion blanket neutronics
International Nuclear Information System (INIS)
Oyama, Yukio
1989-12-01
Phase IIA and IIB experiments on fusion blanket neutronics has been performed on a basis of JAERI/USDOE collaborative program. In the Phase II experimental series, a D-T neutron source and a test blanket were contained by a lithium-carbonate enclosure to adjust the incident neutron spectrum to the test blanket so as to simulate that of a fusion reactor. First two series of the Phase II, IIA and IIB, focused especially on influences of beryllium configurations for neutron multiplying zone to neutronic parameters. Measured parameters were tritium production rate using Li-glass and NE213 scintillators, and Li-metal foil and Lithium-oxide block with liquid scintillation technique; neutron spectrum using NE213 scintillator and proton recoil proportional counter; reaction rate using foil activation technique. These parameters were compared among six different beryllium configurations of the experimental system. Consistency between different techniques for each measured parameter was also tested among different experimental systems and confirmed to be within experimental errors. This report describes, in detail, experimental conditions, assemblies, equipments and neutron source in Part I. The part II compiles all information required for a calculational analysis of this experiment, e.g., dimensions of the target room, target assembly, experimental assembly, their material densities and numerical data of experimental results. This compilation provides benchmark data to test calculation models and computing code systems used for a nuclear design of a fusion reactor. (author)
Genomic clone encoding the α chain of the OKM1, LFA-1, and platelet glycoprotein IIb-IIIa molecules
International Nuclear Information System (INIS)
Cosgrove, L.J.; Sandrin, M.S.; Rajasekariah, P.; McKenzie, I.F.C.
1986-01-01
LFA-1, an antigen involved in cytolytic T lymphocyte-mediated killing, and Mac-1, the receptor for complement component C3bi, constitute a family of structurally and functionally related cell surface glycoproteins involved in cellular interactions. In both mouse and man, Mac-1 (OKM1) and LFA-1 share a common 95-kDa β subunit but are distinguished by their α chains, which have different cellular distributions, apparent molecular masses (165 and 177 kDa, respectively), and peptide maps. The authors report the isolation of a genomic clone from a human genomic library that on transfection into mouse fibroblasts produced a molecule(s) reactive with monoclonal antibodies to OKM1, to LFA-1, and to platelet glycoprotein IIb-IIIa. This gene was cloned by several cycles of transfection of L cells with a human genomic library cloned in λ phase Charon 4A and subsequent rescue of the λ phage. Transfection with the purified recombinant λ DNA yielded a transfectant that expressed the three human α chains of OKM1, LFA-1, and glycoprotein IIb-IIIa, presumably in association with the murine β chain
International Nuclear Information System (INIS)
Gu Jianming; Xu Wenfeng; Wang Xiaodong; Wu Qingyu; Qi Zhengwu; Ruan Changgeng
1993-08-01
Using southern blot, the restriction digests of genomic DNAs in eleven patients with Glanzmann thrombasthenia from ten unrelated kindred were probed with a platelet full-length GP IIb cDNA. An abnormal 2.3 kb Taq I fragment and two 1.65 kb and 0.65 kb fragments with reduced band intensity were found in the genes of two affected siblings from a family originated in city Huang Yan of Zhejiang Province. The Taq I digest of the abnormal gene was further probed with three portions of GP IIb cDNA, revealing that the heterozygous mutation was present in the region around exons 15 ∼ 17 of the GP IIb gene. Two primers for polymerase chain reaction (PCR) were then designed, and a 394 bp PCR product was generated and sequenced, indicating that a stop codon was substituted for an Arg codon at amino acid position 584 of GP IIb, and brought about a premature termination of translation and production of a shortened protein. The Western blot analysis showed that GP IIb and GP IIIa at the platelet surface were apparently deficient, it may be ascribed to the rapid turn-over of GP IIIa uncomplexed with the truncated GP II b. The abnormal 2.3 kb Tag I fragment was used as a specific genetic marker to detect the carrier status of the patient's family. The abnormal allele was proved to be derived from the mother, the two affected siblings are double heterozygotes carrying two different GP II b-defective alleles and one clinically unaffected sister has also inherited this defective allele, while the father carries another unidentified recessive abnormal GP IIb-defective allele
From UV/IR mixing to closed strings
International Nuclear Information System (INIS)
Lopez, Esperanza
2003-01-01
It was shown in [1] that the leading UV/IR mixing effects in noncommutative gauge theories on D-branes are able to capture information about the closed string spectrum of the parent string theory. The analysis was carried out for D-branes on nonsupersymmetric C 3 /Z N orbifolds of Type IIB. In this paper we consider D-branes on twisted circles compactifications of Type II string theory. We find that the signs of the leading UV/IR mixing effects know about the (mass) 2 gap between the lowest modes in NSNS and RR closed string towers. Moreover, the relevant piece of the field theory effective action can be reproduced purely in the language of closed strings. Remarkably, this approach unifies in a single structure, that of a closed string exchange between D-branes, both the leading planar and nonplanar effects associated to the absence of supersymmetry. (author)
International Nuclear Information System (INIS)
Koch, J.A.; Waxman, D.J.
1989-01-01
Phosphorylation of hepatic cytochrome P-450 was studied in isolated hepatocytes incubated in the presence of agents known to stimulate protein kinase activity. Incubation of hepatocytes isolated from phenobarbital-induced adult male rats with [ 32 P]orthophosphate in the presence of N 6 , O 2' -dibutyryl-cAMP (diBtcAMP) or glucagon resulted in the phosphorylation of microsomal proteins that are immunoprecipitable by polyclonal antibodies raised to the phenobarbital-induced P-450 form PB-4 (P-450 gene IIB1). Two-dimensional gel electrophoresis revealed that these 32 P-labeled microsomal proteins consist of a mixture of P-450 PB-4 and the closely related P-450 PB-5 (gene IIB2), both of which exhibited heterogeneity in the isoelectric focusing dimension. Phosphorylation of both P-450 forms was markedly enhanced by diBtcAMP at concentrations as low as 5 μM. Phosphoamino acid analysis of the 32 P-labeled P-450 PB-4 + PB-5 immunoprecipitate revealed that these P-450s are phosphorylated on serine in the isolated hepatocytes. Peptide mapping indicated that the site of phosphorylation in hepatocytes is indistinguishable from the site utilized by cAMP-dependent protein kinase in vitro, which was previously identified as serine-128 for the related rabbit protein P-450 LM2. In vitro analyses revealed that phosphorylation of P-450 PB-4 leads to a loss of monooxygenase activity, suggesting that the posttranslational modification of this P-450 enzyme by cAMP-dependent protein kinase may play a role in the modulation of P-450-dependent monooxygenase activity in vivo
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
Energy Technology Data Exchange (ETDEWEB)
Kim, Eun Seog; Choi, Doo Ho [Soonchunhyang Univ. College of Medicine, Asan (Korea, Republic of); Huh, Seung Jae [Samsung Medical Center, Sungkyunkwan Univ. College of Medicine, Seoul (Korea, Republic of)
1998-03-01
Treatment of choice for uterine cervix cancer stage IIB is radiotherapy. We analyzed survivals, prognostic factors, patterns of failure and complications. This is a retrospective analysis of 167 patients with stage IIB carcinoma of uterine cervix treated with curative external pelvic and high dose rate intracavitary radiotherapy at the Department of Therapeutic Radiology, Soonchunhyang University Hospital from August 1985 to August 1994. All the patients followed up from 3 to 141 months(mean 60 months) and age of patients ranged from 31 to 78 years at presentation(mean : 55 years). Overall complete response rate was 84%. The response rate for squamous cell carcimoma and adenocarcinoma were 86% and 60%, respectively. Overall 5-years survival rate and disease free survival rate was 62 and 59%, respectively. Mass size and treatment response were significant prognostic factors for survival. Pathologic type and parametrial involvement were marginally significants prognostic factors. Local failure was 43 cases, distant metastasis was 14 cases and local failure plus distant metastasis was 3 cases, and most of local failures occurred within 24 months, distant metastasis within 12 months after treatment. Twenty eight(16.8%) patients developed late rectal and urinary complications There were tendency to increasing severity and frequency according to increased fractional dose and total(rectal and bladder) dose. Survival rate was significantly related to tumor size and radiotherapy response. Tumor size should be considered in the clinical staging. To increased survival and local control, clinical trials such as decreasing duration of radiotherapy or addition of chemotherapy is needed. To detect early recurrence, regular follow up after RT is important. Because total rectal and bladder dose affected late complications, meticulous vaginal packing is needed to optimize dose of normal tissues and to decrease late complications.
International Nuclear Information System (INIS)
Van Nagell, J.R.; Maruyama, Y.; Yoneda, J.; Donaldson, E.S.; Hanson, M.B.; Gallion, H.H.; Powell, D.E.; Kryscio, R.J.
1986-01-01
From January, 1977, to December, 1982, twenty-nine patients with bulky (>4 cms diameter) Stage IB or IIB cervical cancer were treated at the University of Kentucky Medical Center by a combination of out-patient neutron brachytherapy (Cf-252) and external pelvic radiation followed by extrafascial hysterectomy. Residual tumor was present in the hysterectomy specimens of 25 per cent. Complications during and following radiation therapy and surgery were minimal and included vaginal stenosis, proctitis, and hemorrhagic cystitis. The mean duration of hospitalization for surgery in these patients was 6.6 days (range 5-15 days) and postoperative morbidity was low. No patient required blood transfusion. Four patients developed urinary tract infections and two had superficial wound separations. Following treatment, patients were seen at monthly intervals for one year, every three months for two years, and every six months thereafter. No patient has been lost to follow-up. Two patients (7 per cent) developed tumor recurrence and have died of disease (1 of distant metastases; 1 local). The remaining 27 patients (93 per cent) are alive and well with no evidence of disease 24-89 months (mean 48 months) after therapy. No radiogenic fistulae or bowel obstruction were observed. These preliminary results suggest that the combination of outpatient neutron brachytherapy, external pelvic radiation, and extrafascial hysterectomy for patients with Stage IB and IIB cervical cancer is well tolerated. Complications associated with this treatment regimen have been minimal, and the recurrence rate is low. The duration of intracavitary neutron brachytherapy was short, and outpatient therapy was well received by patients
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.)
SN 2015as: a low-luminosity Type IIb supernova without an early light-curve peak
Gangopadhyay, Anjasha; Misra, Kuntal; Pastorello, A.; Sahu, D. K.; Tomasella, L.; Tartaglia, L.; Singh, Mridweeka; Dastidar, Raya; Srivastav, S.; Ochner, P.; Brown, Peter J.; Anupama, G. C.; Benetti, S.; Cappellaro, E.; Kumar, Brajesh; Kumar, Brijesh; Pandey, S. B.
2018-05-01
We present results of the photometric (from 3 to 509 d post-explosion) and spectroscopic (up to 230 d post-explosion) monitoring campaign of the He-rich Type IIb supernova (SN) 2015as. The (B - V) colour evolution of SN 2015as closely resemble those of SN 2008ax, suggesting that SN 2015as belongs to the SN IIb subgroup that does not show the early, short-duration photometric peak. The light curve of SN 2015as reaches the B-band maximum about 22 d after the explosion, at an absolute magnitude of -16.82 ± 0.18 mag. At ˜75 d after the explosion, its spectrum transitions from that of a SN II to a SN Ib. P Cygni features due to He I lines appear at around 30 d after explosion, indicating that the progenitor of SN 2015as was partially stripped. For SN 2015as, we estimate a 56Ni mass of ˜0.08 M⊙ and ejecta mass of 1.1-2.2 M⊙, which are similar to the values inferred for SN 2008ax. The quasi-bolometric analytical light-curve modelling suggests that the progenitor of SN 2015as has a modest mass (˜0.1 M⊙), a nearly compact (˜0.05 × 1013 cm) H envelope on top of a dense, compact (˜2 × 1011 cm) and a more massive (˜1.2 M⊙) He core. The analysis of the nebular phase spectra indicates that ˜0.44 M⊙ of O is ejected in the explosion. The intensity ratio of the [Ca II]/[O I] nebular lines favours either a main-sequence progenitor mass of ˜15 M⊙ or a Wolf-Rayet star of 20 M⊙.
International Nuclear Information System (INIS)
Oyen, W.J.G.; Boerman, O.C.; Corstens, F.H.M.; Brouwers, F.M.; Barrett, J.A.; Verheugt, F.W.A.; Ruiter, D.J.; Meer, J.W.M. van der
2000-01-01
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 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 99m Tc-DMP444 and two infected dogs with 37 MBq/kg 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 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 99m Tc-IgG injected dogs (P 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.)
International Nuclear Information System (INIS)
Fitzgerald, L.A.; Poncz, M.; Steiner, B.; Rall, S.C. Jr.; Bennett, J.S.; Phillips, D.R.
1987-01-01
The fibronectin receptor (FnR), the vitronectin receptor (VnR), and the platelet membrane glycoprotein (GP) IIb-IIIa complex are members of a family of cell adhesion receptors, which consist of noncovalently associated α- and β-subunits. The present study was designed to compare the cDNA-derived protein sequences of the α-subunits of human FnR, VnR, and platelet GP IIb. cDNA clones for the α-subunit of the FnR (FnR/sub α/) were obtained from a human umbilical vein endothelial (HUVE) cell library by using an oligonucleotide probe designed from a peptide sequence of platelet GP IIb. cDNA clones for platelet GP IIb were isolated from a cDNA expression library of human erythroleukemia cells by using antibodies. cDNA clones of the VnR α-subunit (VnR/sub α/) were obtained from the HUVE cell library by using an oligonucleotide probe from the partial cDNA sequence for the VnR/sub α/. Translation of these sequences showed that the FNR/sub α/, the VnR/sub α/, and GP IIb are composed of disulfide-linked large (858-871 amino acids) and small (137-158 amino acids) chains that are posttranslationally processed from a single mRNA. A single hydrophobic segment located near the carboxyl terminus of each small chain appears to be a transmembrane domain. The large chains appear to be entirely extracellular, and each contains four repeated putative Ca 2+ -binding domains of about 30 amino acids that have sequence similarities to other Ca 2+ -binding proteins. The identity among the protein sequences of the three receptor α-subunits ranges from 36.1% to 44.5%, with the Ca 2+ -binding domains having the greatest homology. These proteins apparently evolved by a process of gene duplication
Finite temperature corrections to tachyon mass in intersecting D-branes
International Nuclear Information System (INIS)
Sethi, Varun; Chowdhury, Sudipto Paul; Sarkar, Swarnendu
2017-01-01
We continue with the analysis of finite temperature corrections to the Tachyon mass in intersecting branes which was initiated in https://www.doi.org/10.1007/JHEP09(2014)063. 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 https://www.doi.org/10.1016/j.nuclphysb.2011.07.011. 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 https://www.doi.org/10.1007/JHEP09(2014)063 as well as those for intersecting D2 branes.
Monopoles, vortices, domain walls and D-branes: The rules of interaction
International Nuclear Information System (INIS)
Sakai, Norisuke; Tong, David
2005-01-01
Non-abelian gauge theories in the Higgs phase admit a startling variety of BPS solitons. These include domain walls, vortex strings, confined monopoles threaded on vortex strings, vortex strings ending on domain walls, monopoles threaded on strings ending on domain walls, and more. After presenting a self-contained review of these objects, including several new results on the dynamics of domain walls, we go on to examine the possible interactions of solitons of various types. We point out the existence of a classical binding energy when the string ends on the domain wall which can be thought of as a BPS boojum with negative mass. We present an index theorem for domain walls in non-abelian gauge theories. We also answer questions such as: Which strings can end on which walls? What happens when monopoles pass through domain walls? What happens when domain walls pass through each other? (author)
Wess-Zumino terms for AdS D-branes
International Nuclear Information System (INIS)
Hatsuda, Machiko; Kamimura, Kiyoshi
2004-01-01
We show that Wess-Zumino terms for Dp branes with p>0 in the anti-de Sitter (AdS) space are given in terms of 'left-invariant' currents on the super-AdS group or the 'expanded' super-AdS group. As a result there is no topological extension of the super-AdS algebra. In the flat limit the global Lorentz rotational charges of the AdS space turn out to be brane charges of the supertranslation algebra representing the BPS mass. We also show that a D-instanton is described by the GL(1) degree of freedom in the Roiban-Siegel formalism based on the GL(4 vertical bar 4)/[Sp(4)xGL(1)]2 coset
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
International Nuclear Information System (INIS)
Morita, Takeshi; Shiba, Shotaro
2015-01-01
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
Ramond and Neveu-Schwarz paraspinning strings in presence of D-branes
Hamam, D.; Belaloui, N.
2018-03-01
We investigate the theory of an open parafermionic string between two parallel Dp-, Dq-branes in Ramond and Neveu-Schwarz sectors. Trilinear commutation relations between the string variables are postulated and the corresponding ones in terms of modes are derived. The analysis of the spectrum shows that one can again have a free tachyon Neveu-Schwarz model for some values of the order of the paraquantization associated to some values of p and q. The consistency of this model requires the calculation of the partition function and its confrontation with the results of the degeneracies. A perfect agreement between the two results is obtained and the closure of the Virasoro superalgebra is confirmed.
D-brane gases and stabilization of extra dimensions in dilaton gravity
International Nuclear Information System (INIS)
Arapoglu, Savas; Kaya, Ali
2004-01-01
We consider a toy cosmological model with a gas of wrapped Dp-branes in 10-dimensional dilaton gravity compactified on a p-dimensional Ricci flat internal manifold. A consistent generalization of the low energy effective field equations in the presence of a conserved brane source coupled to dilaton is obtained. It is then shown that the compact dimensions are dynamically stabilized in string frame as a result of a balance between negative winding and positive momentum pressures. Curiously, when p=6, i.e., when the observed space is three-dimensional, the dilaton becomes a constant and stabilization in Einstein frame is also realized
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.
D-brane propagation in two-dimensional black hole geometries
International Nuclear Information System (INIS)
Nakayama, Yu; Rey, Soo-Jong; Sugawara, Yuji
2005-01-01
We study propagation of D0-brane in two-dimensional lorentzian black hole backgrounds by the method of boundary conformal field theory of SL(2,R)/U(1) supercoset at level k. Typically, such backgrounds arise as near-horizon geometries of k coincident non-extremal NS5-branes, where 1/k measures curvature of the backgrounds in string unit and hence size of string worldsheet effects. At classical level, string worldsheet effects are suppressed and D0-brane propagation in the lorentzian black hole geometry is simply given by the Wick rotation of D1-brane contour in the euclidean black hole geometry. Taking account of string worldsheet effects, boundary state of the lorentzian D0-brane is formally constructible via Wick rotation from that of the euclidean D1-brane. However, the construction is subject to ambiguities in boundary conditions. We propose exact boundary states describing the D0-brane, and clarify physical interpretations of various boundary states constructed from different boundary conditions. As it falls into the black hole, the D0-brane radiates off to the horizon and to the infinity. From the boundary states constructed, we compute physical observables of such radiative process. We find that part of the radiation to infinity is in effective thermal distribution at the Hawking temperature. We also find that part of the radiation to horizon is in the Hagedorn distribution, dominated by massive, highly non-relativistic closed string states, much like the tachyon matter. Remarkably, such distribution emerges only after string worldsheet effects are taken exactly into account. From these results, we observe that nature of the radiation distribution changes dramatically across the conifold geometry k = 1 (k = 3 for the bosonic case), exposing the 'string - black hole transition' therein
D-brane black holes: Large-N limit and the effective string description
Energy Technology Data Exchange (ETDEWEB)
Hassan, S F [International Centre for Theoretical Physics, Trieste (Italy); Wadia, S R [Theoretical Physics Div., CERN, Geneva (Switzerland)
1997-03-01
We address the derivation of the effective conformal field theory description of the 5-dimensional black hole, modelled by a collection of D1-and D5-branes, from the corresponding low energy U(Q{sub 1}) x U(Q{sub 5}) gauge theory. Finite horizon size at weak coupling requires both Q{sub 1} and Q{sub 5} to be large. We derive the results in the moduli space approximation (say for Q{sub 1} > Q{sub 5}) and appeal to supersymmetry to argue its validity beyond weak coupling. As a result of a combination of quenched Z{sub Q1} Wilson lines and a residual Weyl symmetry, the low-lying excitations of the U(Q{sub 1}) x U(Q{sub 5}) gauge theory are described by an effective N = 4 superconformal field theory with c = 6 in 1 + 1 dimensions, where the space is a circle of radius RQ{sub 1}Q{sub 5}. We also discuss the appearance of a marginal perturbation of the effective conformal field theory for large but finite values of Q{sub 5}. (author). 42 refs.
Finite temperature corrections to tachyon mass in intersecting D-branes
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Sethi, Varun [Department of Physics and Astrophysics, University of Delhi,Delhi 110007 (India); Chowdhury, Sudipto Paul [Institute of Physics, Sachivalaya Marg,Bhubaneswar 751005 (India); Sarkar, Swarnendu [Department of Physics and Astrophysics, University of Delhi,Delhi 110007 (India)
2017-04-19
We continue with the analysis of finite temperature corrections to the Tachyon mass in intersecting branes which was initiated in https://www.doi.org/10.1007/JHEP09(2014)063. 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 https://www.doi.org/10.1016/j.nuclphysb.2011.07.011. 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 https://www.doi.org/10.1007/JHEP09(2014)063 as well as those for intersecting D2 branes.
Simplifying superstring and D-brane actions in AdS4 x CP3 superbackground
International Nuclear Information System (INIS)
Grassi, Pietro Antonio; Sorokin, Dmitri; Wulff, Linus
2009-01-01
By making an appropriate choice for gauge fixing kappa-symmetry we obtain a relatively simple form of the actions for a D = 11 superparticle in AdS 4 x S 7 /Z k , and for a D0-brane, fundamental string and D2-branes in the AdS 4 x CP 3 superbackground. They can be used to study various problems of string theory and the AdS 4 /CFT 3 correspondence, especially in regions of the theory which are not reachable by the OSp(6|4)/U(3) x SO(1,3) supercoset sigma-model. In particular, we present a simple form of the gauge-fixed superstring action in AdS 4 x CP 3 and briefly discuss issues of its T-dualization.
Bipartite field theories: from D-brane probes to scattering amplitudes
Franco, Sebastián
2012-11-01
We introduce and initiate the investigation of a general class of 4d, {N}=1 quiver gauge theories whose Lagrangian is defined by a bipartite graph on a Riemann surface, with or without boundaries. We refer to such class of theories as Bipartite Field Theories (BFTs). BFTs underlie a wide spectrum of interesting physical systems, including: D3-branes probing toric Calabi-Yau 3-folds, their mirror configurations of D6-branes, cluster integrable systems in (0 + 1) dimensions and leading singularities in scattering amplitudes for {N}=4 SYM. While our discussion is fully general, we focus on models that are relevant for scattering amplitudes. We investigate the BFT perspective on graph modifications, the emergence of Calabi-Yau manifolds (which arise as the master and moduli spaces of BFTs), the translation between square moves in the graph and Seiberg duality and the identification of dual theories by means of the underlying Calabi-Yaus, the phenomenon of loop reduction and the interpretation of the boundary operator for cells in the positive Grassmannian as higgsing in the BFT. We develop a technique based on generalized Kasteleyn matrices that permits an efficient determination of the Calabi-Yau geometries associated to arbitrary graphs. Our techniques allow us to go beyond the planar limit by both increasing the number of boundaries of the graphs and the genus of the underlying Riemann surface. Our investigation suggests a central role for Calabi-Yau manifolds in the context of leading singularities, whose full scope is yet to be uncovered.
Aspects of NT ≥ 2 topological gauge theories and D-branes
International Nuclear Information System (INIS)
Blau, M.; Thompson, G.
1996-12-01
Recently, topological field theories with extended N T > 1 topological symmetries have appeared in various contexts, e.g. in the discussion of S-duality in supersymmetry gauge theories, as world volume theories of Dirichlet p-branes in string theory, and in a general discussion of 'balanced' or critical topological theories. Here we will comment on, explain, or expand on various aspects of these theories, thus complementing the already existing discussions of such models in the literature. We comment on various aspects of topological gauge theories possessing N T ≥ 2 topological symmetry: 1. We show that the construction of Vafa-Witten and Dijkgraaf-Moore of 'balanced' topological field theories is equivalent to an earlier construction in terms of N T = 2 superfields inspired by supersymmetric quantum mechanics. 2. We explain the relation between topological field theories calculating signed and unsigned sums of Euler numbers of moduli spaces. 3. We show that the topological twist of N = 4 d = 4 Yang-Mills theory recently constructed by Marcus is formally a deformation of four-dimensional super-BF theory. 4. We construct a novel N T = 2 topological twist of N = 4 d = 3 Yang-Mills theory, a 'mirror' of the Casson invariant model, with certain unusual features (e.g. no bosonic scalar field and hence no underlying equivariant cohomology). 5. We give a complete classification of the topological twists of N = 8 d = 3 Yang-Mills theory and show that they are realized as world-volume theories of Dirichlet two-brane instantons wrapping supersymmetric three-cycles of Calabi-Yau three-folds and G 2 -holonomy Joyce manifolds. 6. We describe the topological gauge theories associated to D-string instantons on holomorphic curves in K3s and Calabi-Yau 3-folds. 48 refs
Dynamical SUSY Breaking at Meta-Stable Minima from D-branes at Obstructed Geometries
Franco, S; Franco, Sebastian; Uranga, Angel M .
2006-01-01
We study the existence of long-lived meta-stable supersymmetry breaking vacua in gauge theories with massless quarks, upon the addition of extra massive flavors. A simple realization is provided by a modified version of SQCD with N_{f,0} < N_c massless flavors, N_{f,1} massive flavors and additional singlet chiral fields. This theory has local meta-stable minima separated from a runaway behavior at infinity by a potential barrier. We find further examples of such meta-stable minima in flavored versions of quiver gauge theories on fractional branes at singularities with obstructed complex deformations, and study the case of the dP_1 theory in detail. Finally, we provide an explicit String Theory construction of such theories. The additional flavors arise from D7-branes on non-compact 4-cycles of the singularity, for which we find a new efficient description using dimer techniques.
New N=1 superconformal field theories in four dimensions from D-brane probes
International Nuclear Information System (INIS)
Aharony, O.; Kachru, S.; Silverstein, E.
1997-01-01
We present several new examples of non-trivial 4D N=1 superconformal field theories. Some of these theories exhibit exotic global symmetries, including non-simply laced groups (such as F 4 ). They are obtained by studying three-brane probes in F-theory compactifications on elliptic Calabi-Yau threefolds. The geometry of the compactification encodes in a simple way the behavior of the gauge coupling and the Kaehler potential on the Coulomb branch of these theories. (orig.)
Realistic D-brane models on warped throats: Fluxes, hierarchies and moduli stabilization
International Nuclear Information System (INIS)
Cascales, J.F.G.; Garcia del Moral, M.P.; Quevedo, F.; Uranga, A.
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 embedded in a full compactification, could give rise to models with all moduli stabilised, and with the potential to lead to de Sitter vacua. Issues of gauge unification, proton stability, supersymmetry breaking and Yukawa couplings are also discussed. (author)
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Levendag, Peter; Gregoire, Vincent; Hamoir, Marc; Voet, Peter; Est, Henrie van der; Heijmen, Ben; Kerrebijn, Jeroen
2005-01-01
Purpose: The objectives of this study are to discuss the intraoperative validation of CT-based boundaries of lymph nodal levels in the neck, and in particular the clinical relevance of the delineation of sublevels IIa and IIb in case of selective radiation therapy (RT). Methods and Materials: To validate the radiologically defined level contours, clips were positioned intraoperatively at the level boundaries defined by surgical anatomy. In 10 consecutive patients, clips were placed, at the time of a neck dissection being performed, at the most cranial border of the neck. Anterior-posterior and lateral X-ray films were obtained intraoperatively. Next, in 3 patients, neck levels were contoured on preoperative contrast-enhanced CT scans according to the international consensus guidelines. From each of these 3 patients, an intraoperative CT scan was also obtained, with clips placed at the surgical-anatomy-based level boundaries. The preoperative (CT-based) and intraoperative (surgery-defined) CT scans were matched. Results: Clips placed at the most cranial part of the neck lined up at the caudal part of the transverse process of the cervical vertebra C-I. The posterior border of surgical level IIa (spinal accessory nerve [SAN]) did not match with the posterior border of CT-based level IIa (internal jugular vein [IJV]). Other surgical boundaries and CT-based contours were in good agreement. Conclusions: The cranial border of the neck, i.e., the cranial border of level IIa/IIb, corresponds to the caudal edge of the lateral process of C-I. Except for the posterior border between level IIa and level IIb, a perfect match was observed between the other surgical-clip-identified levels II-V boundaries (surgical-anatomy) and the CT-based delineation contours. It is argued that (1) because of the parotid gland overlapping part of level II, and (2) the frequent infestation of occult metastatic cells in the lymph channels around the IJV, the division of level II into radiologic
Energy Technology Data Exchange (ETDEWEB)
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
The scales of brane nucleation processes
International Nuclear Information System (INIS)
Alwis, S.P. de
2007-01-01
The scales associated with Brown-Teitelboim-Bousso-Polchinski processes of brane nucleation, which result in changes of the flux parameters and the number of D-branes, are discussed in the context of type IIB models with all moduli stabilized. It is argued that such processes are unlikely to be described by effective field theory
Dery, Jean-Pierre; Campbell, Mark E; Mathias, Jasmine; Pieper, Karen S; Harrington, Robert A; Madan, Mina; Gibson, C Michael; Tolleson, Thaddeus R; O'Shea, J Conor; Tcheng, James E
2007-07-01
This analysis sought to investigate the complementary effect of thienopyridine pretreatment and platelet glycoprotein (GP) IIb/IIIa integrin blockade in coronary stent intervention. Definitive evidence supporting combined antiplatelet therapy consisting of thienopyridine pretreatment and GP IIb/IIIa receptor blockade in patients undergoing percutaneous coronary intervention (PCI) with stent implantation is limited. We retrospectively analyzed clinical outcomes by thienopyridine use in the 2,040 patients randomized to eptifibatide or placebo who underwent PCI in the ESPRIT trial. A total of 901 patients received a loading dose of thienopyridine before PCI (group 1), 123 received thienopyridine pretreatment without a loading dose (group 2), and 1,016 were not treated with thienopyridine before PCI (group 3). The composite incidence of death or myocardial infarction at 30 days was significantly lower in group 1 than in groups 2 and 3 combined (OR, 0.71 [95%CI, 0.52-0.99]; P = 0.0417). A similar trend was seen for the composite of death, myocardial infarction, or urgent target vessel revascularization (unadjusted OR, 0.77 [0.57-1.05]; P = 0.1025). After adjusting for baseline characteristics, these differences were no longer significant. No interactions were identified with eptifibatide assignment for any of the group comparisons. Pretreatment with a loading dose of thienopyridine lowers the rate of ischemic complications regardless of treatment with a GP IIb/IIIa inhibitor. Conversely, the efficacy of eptifibatide is maintained whether or not a loading dose of a thienopyridine is administered. Optimal outcomes are achieved in patients receiving thienopyridine pretreatment along with platelet GP IIb/IIIa inhibitor therapy. (c) 2007 Wiley-Liss, Inc.
Tanigaki, Keiji; Chambliss, Ken L.; Yuhanna, Ivan S.; Sacharidou, Anastasia; Ahmed, Mohamed; Atochin, Dmitriy N.; Huang, Paul L.
2016-01-01
Modest elevations in C-reactive protein (CRP) are associated with type 2 diabetes. We previously revealed in mice that increased CRP causes insulin resistance and mice globally deficient in the CRP receptor Fcγ receptor IIB (FcγRIIB) were protected from the disorder. FcγRIIB is expressed in numerous cell types including endothelium and B lymphocytes. Here we investigated how endothelial FcγRIIB influences glucose homeostasis, using mice with elevated CRP expressing or lacking endothelial FcγRIIB. Whereas increased CRP caused insulin resistance in mice expressing endothelial FcγRIIB, mice deficient in the endothelial receptor were protected. The insulin resistance with endothelial FcγRIIB activation was due to impaired skeletal muscle glucose uptake caused by attenuated insulin delivery, and it was associated with blunted endothelial nitric oxide synthase (eNOS) activation in skeletal muscle. In culture, CRP suppressed endothelial cell insulin transcytosis via FcγRIIB activation and eNOS antagonism. Furthermore, in knock-in mice harboring constitutively active eNOS, elevated CRP did not invoke insulin resistance. Collectively these findings reveal that by inhibiting eNOS, endothelial FcγRIIB activation by CRP blunts insulin delivery to skeletal muscle to cause insulin resistance. Thus, a series of mechanisms in endothelium that impairs insulin movement has been identified that may contribute to type 2 diabetes pathogenesis. PMID:27207525
International Nuclear Information System (INIS)
Aoyama, Tatsumi; Kawai, Hikaru; Shibusa, Yuuichiro
2006-01-01
We investigate the origin of our four-dimensional space-time by considering dynamical aspects of the IIB matrix model using the improved mean field approximation. Previous works have focused on the specific choices of configurations as ansatz which preserve SO(d) rotational symmetry. In this report, an extended ansatz is proposed and examined up to a third-order approximation which includes both the SO(4) ansatz and the SO(7) ansatz in their respective limits. From the solutions of the self-consistency condition represented by the extrema of the free energy of the system, it is found that some of the solutions found in the SO(4) or SO(7) ansatz disappear in the extended ansatz. This implies that the extension of ansatz can be used to distinguish stable solutions from unstable solutions. It is also found that there is a non-trivial accumulation of extrema including the SO(4)-preserving solution, which may lead to the formation of a plateau. (author)
Maldonado-Barragán, Antonio; Caballero-Guerrero, Belén; Jiménez, Esther; Jiménez-Díaz, Rufino; Ruiz-Barba, José L; Rodríguez, Juan M
2009-07-31
Enterocin C (EntC), a class IIb bacteriocin was purified from culture supernatants of Enterococcus faecalis C901, a strain isolated from human colostrum. Enterocin C consists of two distinct peptides, named EntC1 and EntC2, whose complementary action is required for full antimicrobial activity. The structural genes entC1 and entC2 encoding enterocins EntC1 and EntC2, respectively, and that encoding the putative immunity protein (EntCI) are located in the 9-kb plasmid pEntC, harboured by E. faecalis C901. The N-terminal sequence of both antimicrobial peptides revealed that EntC1 (4284 Da) is identical to Ent1071A, one of the two peptides that form enterocin 1071 (Ent1071), a bacteriocin produced by E. faecalis BFE 1071. In contrast, EntC2 (3867 Da) presents the non-polar alanine residue at position 17 (Ala(17)) instead of the polar threonine residue (Thr(17)) in Ent1071B, the second peptide constituting Ent1071. In spite of peptide similarities, EntC differs from Ent1071 in major aspects, including the complementary activity among its constitutive peptides and its wider inhibitory spectrum of activity. Different amphiphilic alpha-helical conformations between EntC2 and Ent1071B could explain both, acquired complementary activity and increased antimicrobial spectrum.
Extended no-scale structure and {alpha}'{sup 2} corrections to the type IIB action
Energy Technology Data Exchange (ETDEWEB)
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
International Nuclear Information System (INIS)
Ogino, Ichiro; Okamoto, Naoyuki; Andoh, Kazuo; Kitamura, Tatsuo; Okajima, Hiroyuki; Matsubara, Sho
1997-01-01
Purpose: To define the influence of the tumor size measured by computed tomography (CT) and lymph node involvement detected by CT in patients treated with radiation therapy for Stage IIB-IVA carcinoma of intact uterine cervix. Methods and Materials: This was a retrospective analysis of 233 patients with uterine cervical cancer managed with both external irradiation and high-dose-rate intracavitary brachytherapy (HDR-ICR) at Kanagawa Cancer Center. The results were analyzed for the end points of absolute survival (AS), disease-free survival (DFS), pelvic control (PC), and central control (CC). The parameters of stage, CT-measured anterior-posterior (AP) cervix size, and CT-detected lymph node metastases were evaluated using univariate and multivariate analysis. Results: The stage, AP cervix size, and lymph node involvement were significant pretreatment factors in univariate analysis with respect to AS, DFS, PC, and CC. Multivariate analysis confirmed that significant risk was associated with certain prognostic parameters. Those in terms of AS, in order of decreasing significance, were lymph node involvement, AP cervix size, age, and total HDR-ICR dose. When DFS was studied, lymph node involvement and AP cervix size were demonstrated to have a significant effect. Stage and lymph node involvement significantly affected PC. Conclusion: Because the International Federation of Gynecological Obstetrics staging system fails to incorporate important prognostic information about tumor volume and lymph node involvement, CT-detected lymph node metastases as well as CT-measured cervix size should be determined as complementary additional prognostic measures
Directory of Open Access Journals (Sweden)
Arfan Bakhtiar
2017-01-01
PT IIB is a manufacturing companywith major product Carton box packaging and Pulp Tray and Pallet as side products. This products using materials cardboard, scrap paper and wood. Company using calculations with adding material costs, employees’ salary costs in each activity and% profit. The bigsize product need large space, demanding supply system of Just In Time (JIT, is timely in production only to order, if there is an additional need to do overtime. So it takes time calculation standard that can be estimated lead time. So, need a method to determine an accurate cost to unify the cost of each activity, support costs and standard time. The method used is the Time-Driven Activity Based Costing (TDABC. TDABC is a method of formulating the charges on the basis of time, all of the resources used in the production are converted into units of time. The results of this research to acquire all of the costs related to production processes and support costs, gain time standard that is necessary to make three types of products and obtain a calculation of the cost of production for Box RSC Rp 4.006,-, Box DC Rp 4.449,-, Pulp Tray Rp 350,- and Pallet Kayu Rp 155.902,-,and obtain comparative results of the calculation TDABC method and company.
Seifertová, Mária; Jarkovský, Jiří; Šimková, Andrea
2016-04-01
The genes of major histocompatibility complex (MHC) provide an excellent opportunity to study host-parasite relationships because they are expected to evolve in response to parasites and variation in parasite communities. In this study, we investigated the potential role of parasite-mediated selection acting on MHC class IIB (DAB) genes in European chub (Squalius cephalus) natural populations. We found significant differences between populations in metazoan parasites, neutral and adaptive genetic diversities. The analyses based on pairwise data revealed that populations with dissimilar MHC allelic profiles were geographically distant populations with significantly different diversity in microsatellites and a dissimilar composition of parasite communities. The results from the generalized estimating equations method (GEE) on the level of individuals revealed that metazoan parasite load in European chub was influenced by the diversity of DAB alleles as well as by the diversity of neutral genetic markers and host traits reflecting condition and immunocompetence. The multivariate co-inertia analysis showed specific associations between DAB alleles and parasite species. DAB1-like alleles were more involved in associations with ectoparasites, while DAB3-like alleles were positively associated with endoparasites which could suggest potential differences between DAB genes caused by different selection pressure. Our study revealed that parasite-mediated selection is not the only variable affecting MHC diversity in European chub; however, we strongly support the role of neutral processes as the main driver of DAB diversity across populations. In addition, our study contributes to the understanding of the evolution of MHC genes in wild living fish.
Zhu, Jieqing; Choi, Won-Seok; McCoy, Joshua G; Negri, Ana; Zhu, Jianghai; Naini, Sarasija; Li, Jihong; Shen, Min; Huang, Wenwei; Bougie, Daniel; Rasmussen, Mark; Aster, Richard; Thomas, Craig J; Filizola, Marta; Springer, Timothy A; Coller, Barry S
2012-03-14
An integrin found on platelets, α(IIb)β(3) mediates platelet aggregation, and α(IIb)β(3) antagonists are effective antithrombotic agents in the clinic. Ligands bind to integrins in part by coordinating a magnesium ion (Mg(2+)) located in the β subunit metal ion-dependent adhesion site (MIDAS). Drugs patterned on the integrin ligand sequence Arg-Gly-Asp have a basic moiety that binds the α(IIb) subunit and a carboxyl group that coordinates the MIDAS Mg(2+) in the β(3) subunits. They induce conformational changes in the β(3) subunit that may have negative consequences such as exposing previously hidden epitopes and inducing the active conformation of the receptor. We recently reported an inhibitor of α(IIb)β(3) (RUC-1) that binds exclusively to the α(IIb) subunit; here, we report the structure-based design and synthesis of RUC-2, a RUC-1 derivative with a ~100-fold higher affinity. RUC-2 does not induce major conformational changes in β(3) as judged by monoclonal antibody binding, light scattering, gel chromatography, electron microscopy, and a receptor priming assay. X-ray crystallography of the RUC-2-α(IIb)β(3) headpiece complex in 1 mM calcium ion (Ca(2+))/5 mM Mg(2+) at 2.6 Å revealed that RUC-2 binds to α(IIb) the way RUC-1 does, but in addition, it binds to the β(3) MIDAS residue glutamic acid 220, thus displacing Mg(2+) from the MIDAS. When the Mg(2+) concentration was increased to 20 mM, however, Mg(2+) was identified in the MIDAS and RUC-2 was absent. RUC-2's ability to inhibit ligand binding and platelet aggregation was diminished by increasing the Mg(2+) concentration. Thus, RUC-2 inhibits ligand binding by a mechanism different from that of all other α(IIb)β(3) antagonists and may offer advantages as a therapeutic agent.
Budnik, Ivan; Shenkman, Boris; Savion, Naphtali
2015-01-01
Thrombus formation in the injured vessel wall is a highly complex process involving various blood-born components that go through specific temporal and spatial changes as observed by intravital videomicroscopy. Platelets bind transiently to the developing thrombus and may either become stably incorporated into or disengage from the thrombus. The aim of the present study was to reveal the processes involved in the formation of a stable thrombus. Platelet-rich plasma and washed platelets were studied by the aggregometer. The aggregate stability was challenged by eptifibatide. Platelet Triton-insoluble fraction was prepared and the actin and αIIb content in the cytoskeleton was analyzed by western blot. Maximal actin polymerization is achieved 1min after platelet activation while maximal αIIbβ3-actin cytoskeleton association requires 5 to 10min of activation and fibrinogen-mediated platelet-to-platelet bridging. Thus, actin polymerization is dependent on platelet activation and requires neither αIIbβ3 integrin occupation nor platelet aggregation. Formation of a stable aggregate requires platelet activation for more than 1min, complete increase in actin cytoskeleton fraction and partial association of αIIbβ3 with the actin cytoskeleton. However, direct αIIbβ3 activation is not sufficient for cytoskeleton complex formation. Thus, stable αIIbβ3-fibrinogen interaction, representing stable aggregate, is achieved after more than 1min agonist activation, involving inside-out and outside-in signaling but not after direct integrin activation, involving only outside-in signaling. Formation of a stable fibrinogen-αIIbβ3-actin cytoskeleton complex is the result of the combined effect of platelet stimulation by soluble agonists, activation of αIIbβ3, fibrinogen binding and platelet-to-platelet bridging. Copyright © 2014 Elsevier Ltd. All rights reserved.
Bustos Ruiz, M.; Alcaín Tejada, F.J.; Padilla-Alvarez, F.
1981-01-01
Dissociated ciliary ganglia of 8 days embryos were cultured in heart conditioned medium, employing differents substrata types: collagen, po¬lyornithines (types: IB,IIB and IC) and collagen plus polyornithine IB. The results from neuron survival (with and without prolongations) and non neuronal cells it obtained graphically. The polyornithines mollecular weights are discussed respect inductor factors binding for conditioned medium. The type IB is better than others types (IIB y IC), but collag...
International Nuclear Information System (INIS)
Piver, M.S.; Krishnamsetty, R.M.; Emrich, L.J.
1985-01-01
Twenty patients with Stage IIB carcinoma of the cervix who did not undergo pretherapy para-aortic lymphadenectomy, but who had negative preradiation therapy lymphangiograms, were treated with pelvic radiation plus hydroxyurea. Patients received a median of 5020 rads of pelvic radiation plus 4000 rads of radium to point A. During radiation therapy and for a total of 12 weeks, patients received hydroxyurea administered at a dose of 80 mg/kg of body weight every 3 days if the white blood cell count was greater than or equal to 2,500/mm3 and platelets were greater than or equal to 75,000/mm3. The median follow-up time was 28 months (6 to 83 months). The estimated 5-year survival rate was 92%. Seventeen patients are alive with no evidence of disease (median, 28 months); one died of intercurrent disease with no evidence of disease (17 months); one is alive with no evidence of disease after recurrence (18 months); and one died of cervical cancer (22 months). The survival rate of patients with nonsurgically staged negative pretherapy lymphangiograms who had Stage IIB cervical cancer treated by pelvic radiation therapy plus hydroxyurea approximated the improved survival rate reported for patients with negative pretherapy para-aortic lymphadenectomy who were treated with pelvic radiation therapy plus hydroxyurea. Both studies would suggest that pelvic radiation plus hydroxyurea improves the rate of survival in patients with Stage IIB cervical cancer
Garg, R R; Bally-Cuif, L; Lee, S E; Gong, Z; Ni, X; Hew, C L; Peng, C
1999-07-20
A full-length cDNA encoding for activin type IIB receptor (ActRIIB) was cloned from zebrafish embryos. It encodes a protein with 509 amino acids consisting of a signal peptide, an extracellular ligand binding domain, a single transmembrane region, and an intracellular kinase domain with predicted serine/threonine specificity. The extracellular domain shows 74-91% sequence identity to human, bovine, mouse, rat, chicken, Xenopus and goldfish activin type IIB receptors, while the transmembrane region and the kinase domain show 67-78% and 82-88% identity to these known activin IIB receptors, respectively. In adult zebrafish, ActRIIB mRNA was detected by RT-PCR in the gonads, as well as in non-reproductive tissues, including the brain, heart and muscle. In situ hybridization on ovarian sections further localized ActRIIB mRNA to cytoplasm of oocytes at different stages of development. Using whole-mount in situ hybridization, ActRIIB mRNA was found to be expressed at all stages of embryogenesis examined, including the sphere, shield, tail bud, and 6-7 somite. These results provide the first evidence that ActRIIB mRNA is widely distributed in fish embryonic and adult tissues. Cloning of zebrafish ActRIIB demonstrates that this receptor is highly conserved during vertebrate evolution and provides a basis for further studies on the role of activin in reproduction and development in lower vertebrates.
Tsume, Yasuhiro; Igawa, Naoto; Drelich, Adam J; Amidon, Gregory E; Amidon, Gordon L
2018-01-01
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. 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 gastrointestinal simulator 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 © 2018. Published by Elsevier Inc.
International Nuclear Information System (INIS)
Johnson, C.V.
1998-01-01
The nature of M-theory on K3 x I, where I is a line interval, is considered, with a view towards formulating a ''matrix theory'' representation of that situation. Various limits of this compactification of M-theory yield a number of well known N=1 six-dimensional compactifications of the heterotic and type I string theories. Geometrical relations between these limits give rise to string/string dualities between some of these compactifications. At a special point in the moduli space of compactifications, this motivates a partial definition of the matrix theory representation of the M-theory on K3 x I as the large N limit of a certain type IA orientifold model probed by a conglomerate of N D-branes. Such a definition in terms of D-branes and orientifold planes is suggestive, but necessarily incomplete, due to the low amount of supersymmetry. It is proposed - following hints from the orientifold model - that the complete matrix theory representation of the K3 x I compactified M-theory is given by the large N limit of compactification - on a suitable ''dual'' surface - of the ''little heterotic string'' N=1 six-dimensional quantum theories. (orig.)
Blankenship, J C; Tasissa, G; O'Shea, J C; Iliadis, E A; Bachour, F A; Cohen, D J; Lui, H K; Mann, T; Cohen, E; Tcheng, J E
2001-09-01
We sought to determine whether eptifibatide decreases the incidence of in-laboratory angiographic complications and to determine the relationship of angiographically evident complications to elevations of creatine kinase-MB (CK-MB) enzyme levels during percutaneous coronary intervention. In the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial, eptifibatide during coronary intervention was associated with decreased ischemic complications at 48 h and 30 days. Patients (n = 2,064) were randomized to placebo versus eptifibatide (two 180 microg/kg boluses 10 min apart and as a continuous infusion of 2 microg/kg per min) during percutaneous coronary stenting. Angiographic complications including major dissection, distal embolization, residual thrombus, abrupt closure, residual stenosis >50% and side-branch occlusion were prospectively recorded by the operator. Creatine kinase-MB levels were measured after the procedure and every 6 h thereafter. The incidence of angiographic complications and CK-MB elevation was determined for eptifibatide versus placebo groups. Eptifibatide-treated patients demonstrated nonsignificant trends toward fewer angiographic complications (10 vs. 12% for placebo patients, p = 0.13) and, for patients with angiographic complications, fewer subsequent CK-MB elevations (43 vs. 50% for placebo patients, p = 0.31). In patients without any angiographic complications, the incidence of CK-MB elevation >3 times the normal was 7% with placebo and 4% with eptifibatide (p = 0.003). Eptifibatide during nonurgent coronary stent intervention only minimally (and insignificantly) reduces the incidence of angiographic complications and subsequent CK-MB elevations in patients developing an angiographic complication. The greater effect is to reduce myocardial infarction in patients undergoing otherwise uneventful coronary stent implantation as well as in the overall study population.
Chan, Jeremy Y; Greenfield, Stephen T; Soukup, Dylan S; Do, Huong T; Deland, Jonathan T; Ellis, Scott J
2015-12-01
Correction of forefoot abduction in stage IIb adult acquired flatfoot likely depends on the amount of lateral column lengthening (LCL) performed, although this represents only one aspect of a successful reconstruction. The purpose of this study was to evaluate the correlation between common reconstructive variables and the observed change in forefoot abduction. Forty-one patients who underwent flatfoot reconstruction involving an Evans-type LCL were assessed retrospectively. Preoperative and postoperative anteroposterior (AP) radiographs of the foot at a minimum of 40 weeks (mean, 2 years) after surgery were reviewed to determine correction in forefoot abduction as measured by talonavicular coverage (TNC) angle, talonavicular uncoverage percent, talus-first metatarsal (T-1MT) angle, and lateral incongruency angle. Fourteen demographic and intraoperative variables were evaluated for association with change in forefoot abduction including age, gender, height, weight, body mass index, as well as the amount of LCL and medializing calcaneal osteotomy performed, LCL graft type, Cotton osteotomy, first tarsometatarsal fusion, flexor digitorum longus transfer, spring ligament repair, gastrocnemius recession and any one of the modified McBride/Akin/Silver procedures. Two variables significantly affected the change in lateral incongruency angle. These were weight (P = .04) and the amount of LCL performed (P < .001). No variables were associated with the change in TNC angle, talonavicular uncoverage percent, or T-1MT angle. Multivariate regression analysis revealed that LCL was the only significant predictor of the change in lateral incongruency angle. The final regression model for LCL showed a good fit (R2 = 0.70, P < .001). Each millimeter of LCL corresponded to a 6.8-degree change in lateral incongruency angle. Correction of forefoot abduction in flatfoot reconstruction was primarily determined by the LCL procedure and could be modeled linearly. We believe that the
Ahmed, Mostafa M; Heckman, W Wesley; Dailey, Seth H
2013-03-01
Autism spectrum disorders (ASDs) are commonly associated with Tourette syndrome (TS). TS is classically associated with tic production. A tic is defined as sudden, brief, involuntary production of movement (motor tics) or sound (phonic tics). Case report. We present a case report of a 14-year-old boy with ASD and vocal tics. Vocal tic frequency was nearly 2000 per day and 90 dB in volume. He presented to our laryngology clinic after multiple failed attempts of pharmacologic management of vocal fold botulinum toxin injection. After evaluation in our clinic, we recommended a lateralization (type IIB) thyroplasty. An autologous cartilage graft from the superior thyroid ala was used and held in place with a bioresorbable mesh. Using 4-0 prolene sutures, the mesh was secured in place. The operation was well tolerated with minimal signs of aspiration, and he was discharged to his home within 48 hours. Six months postoperatively, there was 90% reduction in tic frequency and 50% reduction in intensity. Additionally, he has shown improved ability to converse with his peers, participate in school activities, and even has improved nutritional status. Alteration of laryngeal geometry could serve as an effective site of intervention for intractable phonic tics. Reduction of phonic tic frequency and intensity may also stimulate language development in patients ASD. We also demonstrate additional use of bioresorbable plates in pediatric laryngeal framework surgery. Additional neurophysiologic studies are needed to explore the mechanism by which midline lateralization thyroplasty influences phonic tic generation. Copyright © 2013 The Voice Foundation. Published by Mosby, Inc. All rights reserved.
Panés, Julian; Sandborn, William J; Schreiber, Stefan; Sands, Bruce E; Vermeire, Séverine; D'Haens, Geert; Panaccione, Remo; Higgins, Peter D R; Colombel, Jean-Frederic; Feagan, Brian G; Chan, Gary; Moscariello, Michele; Wang, Wenjin; Niezychowski, Wojciech; Marren, Amy; Healey, Paul; Maller, Eric
2017-06-01
Tofacitinib is an oral, small-molecule Janus kinase inhibitor that is being investigated for IBD. We evaluated the efficacy and safety of tofacitinib for induction and maintenance treatment in patients with moderate-to-severe Crohn's disease (CD). We conducted two randomised, double-blind, placebo-controlled, multicentre phase IIb studies. Adult patients with moderate-to-severe CD were randomised to receive induction treatment with placebo, tofacitinib 5 or 10 mg twice daily for 8 weeks. Those achieving clinical response-100 or remission were re-randomised to maintenance treatment with placebo, tofacitinib 5 or 10 mg twice daily for 26 weeks. Primary endpoints were clinical remission at the end of the induction study, and clinical response-100 or remission at the end of the maintenance study. 180/280 patients randomised in the induction study were enrolled in the maintenance study. At week 8 of induction, the proportion of patients with clinical remission was 43.5% and 43.0% with 5 and 10 mg twice daily, respectively, compared with 36.7% in the placebo group (p=0.325 and 0.392 for 5 and 10 mg twice daily vs placebo). At week 26 of maintenance, the proportion of patients with clinical response-100 or remission was 55.8% with tofacitinib 10 mg twice daily compared with 39.5% with tofacitinib 5 mg twice daily and 38.1% with placebo (p=0.130 for 10 mg twice daily vs placebo). Compared with placebo, the change in C-reactive protein from baseline was statistically significant (ptofacitinib. NCT01393626 and NCT01393899. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
Surface/state correspondence and bulk local operators in pp-wave holography
Directory of Open Access Journals (Sweden)
Nakwoo Kim
2015-12-01
Full Text Available We apply the surface/state correspondence proposal of Miyaji et al. to IIB pp-waves and propose that the bulk local operators should be instantonic D-branes. In line with ordinary AdS/CFT correspondence, the bulk local operators in pp-waves also create a hole, or a boundary, in the dual gauge theory as pointed out by H. Verlinde, and by Y. Nakayama and H. Ooguri. We also present simple calculations which illustrate how to extract the spacetime metric of pp-waves from instantonic D-branes in boundary state formalism.
Energy Technology Data Exchange (ETDEWEB)
Salum, Resalla; Lopes, Edison R.; Souza, Maria A.H. de [Faculdade de Medicina do Triangulo Mineiro, Uberaba, MG (Brazil). Hospital Escola
1995-07-01
Patients with IB, IIa and in initial IIb cervical cancer were randomized for combined therapy, consisting of one or two radium insertion followed by Wertheim Meigs operation performed 40 days later. We look for the early and late complications of the treatment, residual cancer after radiotherapy and survival without recurrence. The project begin in 1965 and ended in 1986. All the operations were done by one of the investigators and 116 patients were analysed. The age ranged from 21 to 75 years with an average of 4.18 years. During the operations 31 (26.72%) patients needed 1.500 cc or greater amount of blood transfusion and we have 3 iliac veins lesions. Managing the ureters, we do our best to leave the posterior fascia as intact as possible. Post operative complications ranged from minor (fever, localised pelvic infections, temporary popliteal nerve paralysis) to evisceration (3 patients) deep venous thrombosis (3 patients) and two early urinary fistulas. Late complications were seen in patients submitted to sequential teletherapy irradiation. One uretrovaginal fistula occurred 10 month after treatment, another one, 7 years later and the third one 24 years later. One patient develop hydronefrosis and enterocolite after 7.000 rads of teletherapy and another one rectovaginal fistula 13 years after initial therapy. The shortening of the vagina making impossible the intercourse was seen in 7 patients. By the histological examination, the cervix was sterilized in 73.3 % of the patients. Residual cancer was found according the original size of the tumour and the stage of the disease. Studying different combinations between the existence of residual cervical cancer with positive or negative limphnodes and making a correlation with survival, we found the critical points is to have positive cervix and positive lymphonodes. The five years survival (life table methodology) for stage 1 lesion was 96%; stage II, 67%. At ten years survival was slighted different. With positive
Energy Technology Data Exchange (ETDEWEB)
Maeda, Keiichi [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Katsuda, Satoru [RIKEN (The Institute of Physical and Chemical Research) Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Bamba, Aya [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258 (Japan); Terada, Yukikatsu [Graduate School of Science and Engineering, Saitama University, Shimo-Okubo 255, Sakura, Saitama 338-8570 (Japan); Fukazawa, Yasushi, E-mail: keiichi.maeda@kusastro.kyoto-u.ac.jp [Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
2014-04-20
Type IIb supernova (SN) 2011dh, with conclusive detection of an unprecedented yellow supergiant (YSG) progenitor, provides an excellent opportunity to deepen our understanding on the massive star evolution in the final centuries toward the SN explosion. In this paper, we report on detection and analyses of thermal X-ray emission from SN IIb 2011dh at ∼500 days after the explosion on Chandra archival data, providing a solidly derived mass-loss rate of a YSG progenitor for the first time. We find that the circumstellar media should be dense, more than that expected from a Wolf-Rayet (W-R) star by one order of magnitude. The emission is powered by a reverse shock penetrating into an outer envelope, fully consistent with the YSG progenitor but not with a W-R progenitor. The density distribution at the outermost ejecta is much steeper than that expected from a compact W-R star, and this finding must be taken into account in modeling the early UV/optical emission from SNe IIb. The derived mass-loss rate is ∼3 × 10{sup –6} M {sub ☉} yr{sup –1} for the mass-loss velocity of ∼20 km s{sup –1} in the final ∼1300 yr before the explosion. The derived mass-loss properties are largely consistent with the standard wind mass-loss expected for a giant star. This is not sufficient to be a main driver to expel nearly all the hydrogen envelope. Therefore, the binary interaction, with a huge mass transfer having taken place at ≳ 1300 yr before the explosion, is a likely scenario to produce the YSG progenitor.
Tcheng, James E; Lim, Ing Haan; Srinivasan, Shankar; Jozic, Joseph; Gibson, C Michael; O'Shea, J Conor; Puma, Joseph A; Simon, Daniel I
2009-02-01
Only limited data describe relationships between stent parameters (length and diameter), adverse events after percutaneous coronary intervention, and effects of platelet glycoprotein IIb/IIIa blockade by stent parameters. In this post hoc analysis of the 1983 patients receiving a stent in the Enhanced Suppression of the Platelet Glycoprotein IIb/IIIa Receptor with Integrilin Therapy randomized percutaneous coronary intervention trial of eptifibatide versus placebo, rates of the major adverse cardiac event (MACE) end point (death, myocardial infarction, urgent target-vessel revascularization, or thrombotic bailout) at 48 hours and 1 year were correlated with stent parameters and then analyzed by randomization to eptifibatide versus placebo. In the placebo group, MACE increased with number of stents implanted, total stent length (by quartiles of or=30 mm), and total stented vessel area (by quartiles of area or=292 mm(2)). By stent parameters, MACE at 48 hours was reduced in the eptifibatide group at stent lengths of 18 to or=30 mm (OR, 0.43; 95% CI, 0.25 to 0.75; P=0.003), stent diameters of >2.5 to <3.5 mm (OR, 0.56; 95% CI, 0.39 to 0.82; P=0.002), and with 2 stents implanted (OR, 0.39; 95% CI, 0.22 to 0.69; P=0.001). In the placebo group, near-linear relationships were observed between both increasing stent length and increasing stented vessel area and MACE at 48 hours and 1 year (all, P<0.001); these gradients were flattened in the eptifibatide group (P=0.005 for stent length). Stent parameters predict MACE after percutaneous coronary intervention. Glycoprotein IIb/IIIa blockade mitigates much of the hazard of increasing procedural complexity.
Fernandes, Laura S; Tcheng, James E; O'Shea, J Conor; Weiner, Bonnie; Lorenz, Todd J; Pacchiana, Cindy; Berdan, Lisa G; Maresh, Kelly J; Joseph, Diane; Madan, Mina; Mann, Tift; Kilaru, Rakhi; Hochman, Judith S; Kleiman, Neal S
2002-09-18
The study was done to determine whether eptifibatide, a platelet glycoprotein (GP) IIb/IIIa antagonist, prevents ischemic complications following percutaneous coronary interventions (PCIs) in women as well as in men. Eptifibatide reduces ischemic complications after nonurgent coronary stent interventions. We compared outcomes in women (n = 562) and men (n = 1,502) enrolled in the Enhanced Suppression of the Platelet GP IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial of double-bolus eptifibatide during PCI. Women in the ESPRIT trial were older, and more frequently had hypertension, diabetes mellitus, or acute coronary syndromes, but were less likely to have prior PCI or coronary artery bypass graft surgery. The primary end point, a composite at 48 h of death, myocardial infarction (MI), urgent target vessel revascularization (TVR), and unplanned GP IIb/IIIa use, occurred in 10.5% of women and 7.9% of men (p = 0.082). The composite of death, MI, or TVR after one year occurred in 24.5% of women compared with 18% of men (p = 0.0008). At 48 h, eptifibatide reduced the composite of death, MI, and TVR from 14.5% to 6.0% in women versus 9.0% to 6.8% in men. At one year, these differences persisted: 28.9% versus 20.0% for women and 19.5% versus 16.6% for men. No statistical interaction existed between treatment and gender at either 48 h (p = 0.063) or one year (p = 0.2). Bleeding occurred more commonly in women (5.5% vs. 2.6%, p = 0.002), and was more common in eptifibatide-treated women. After adjustment for age, weight, and hypertension, no interaction between treatment and gender was present. Eptifibatide is effective to prevent ischemic complications of PCI in women and may eliminate gender-related differences in PCI outcomes.
Directory of Open Access Journals (Sweden)
Joel Raborn
Full Text Available The Asp of the RGD motif of the ligand coordinates with the β I domain metal ion dependent adhesion site (MIDAS divalent cation, emphasizing the importance of the MIDAS in ligand binding. There appears to be two distinct groups of integrins that differ in their ligand binding affinity and adhesion ability. These differences may be due to a specific residue associated with the MIDAS, particularly the β3 residue Ala(252 and corresponding Ala in the β1 integrin compared to the analogous Asp residue in the β2 and β7 integrins. Interestingly, mutations in the adjacent to MIDAS (ADMIDAS of integrins α4β7 and αLβ2 increased the binding and adhesion abilities compared to the wild-type, while the same mutations in the α2β1, α5β1, αVβ3, and αIIbβ3 integrins demonstrated decreased ligand binding and adhesion. We introduced a mutation in the αIIbβ3 to convert this MIDAS associated Ala(252 to Asp. By combination of this mutant with mutations of one or two ADMIDAS residues, we studied the effects of this residue on ligand binding and adhesion. Then, we performed molecular dynamics simulations on the wild-type and mutant αIIbβ3 integrin β I domains, and investigated the dynamics of metal ion binding sites in different integrin-RGD complexes. We found that the tendency of calculated binding free energies was in excellent agreement with the experimental results, suggesting that the variation in this MIDAS associated residue accounts for the differences in ligand binding and adhesion among different integrins, and it accounts for the conflicting results of ADMIDAS mutations within different integrins. This study sheds more light on the role of the MIDAS associated residue pertaining to ligand binding and adhesion and suggests that this residue may play a pivotal role in integrin-mediated cell rolling and firm adhesion.
DEFF Research Database (Denmark)
Schoos, Mikkel; De Luca, Giuseppe; Dangas, George D
2016-01-01
AIMS: In the HORIZONS-AMI trial, bivalirudin compared to unfractionated heparin (UFH) plus a glycoprotein IIb/IIIa inhibitor (GPI) improved net clinical outcomes in patients undergoing primary percutaneous coronary intervention (PCI) at the cost of an increased rate of acute stent thrombosis. We...... sought to examine whether these effects are dependent on time to treatment. METHODS AND RESULTS: The interaction between anticoagulation regimen and symptom onset to first balloon inflation time (SBT) on the 30-day and three-year rates of major adverse cardiac events (MACE) was examined in 3...
Jerkstrand, A.; Ergon, M.; Smartt, S. J.; Fransson, C.; Sollerman, J.; Taubenberger, S.; Bersten, M.; Spyromilio, J.
2015-01-01
We investigate line formation processes in Type IIb supernovae (SNe) from 100 to 500 days post-explosion using spectral synthesis calculations. The modelling 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 modelling of the [O I] λλ6300, 6364 lines constrains the progenitors of these three SNe to the MZAMS = 12-16 M⊙ range (ejected oxygen masses 0.3-0.9 M⊙), with SN 2011dh towards the lower end and SN 1993J towards the upper end of the range. The high ejecta masses from MZAMS ≳ 17 M⊙ progenitors give rise to brighter nebular phase emission lines than observed. Nucleosynthesis analysis thus supports a scenario of low-to-moderate mass progenitors for Type IIb SNe, and by implication an origin in binary systems. We demonstrate how oxygen and magnesium recombination lines may be combined to diagnose the magnesium mass in the SN ejecta. For SN 2011dh, a magnesium mass of 0.02-0.14 M⊙ is derived, which gives a Mg/O production ratio consistent with the solar value. Nitrogen left in the He envelope from CNO burning gives strong [N II] λλ6548, 6583 emission lines that dominate over Hα emission in our models. The hydrogen envelopes of Type IIb SNe are too small and dilute to produce any noticeable Hα emission or absorption after ~150 days, and nebular phase emission seen around 6550 Å is in many cases likely caused by [N II] λλ6548, 6583. Finally, the influence of radiative transport on the emergent line profiles is investigated. Significant line blocking in the metal core remains for several hundred days, which affects the emergent spectrum. These radiative transfer effects lead to early-time blueshifts of the emission line peaks, which gradually
International Nuclear Information System (INIS)
Sanchez, Doris; Falquez, Roberto
2002-01-01
We realized study of retrospective accomplished in course of years 1998-2000, reviewing clinical charts of statistical department of ION SOLCA. We reviewed 544 cases in 1998, 603 patients in 1999, and 630 cases in 2000. In the radiotherapy service, 133 patients received treatment with external radiotherapy between February 1998 to February 1999 in IIB, IIIA, IIIB stages and only 80 patients were treated with external radiotherapy and scintiscanning of low dose rate in the same stages between March 1999 to March 2000. (The author)
Kumar, Santosh; Bose, Debojit; Suryawanshi, Hemant; Sabharwal, Harshana; Mapa, Koyeli; Maiti, Souvik
2011-01-01
Rev is an essential HIV-1 regulatory protein which binds to the Rev responsive element (RRE) present within the env gene of HIV-1 RNA genome. This binding facilitates the transport of the RNA to the cytoplasm, which in turn triggers the switch between viral latency and active viral replication. Essential components of this complex have been localized to a minimal arginine rich Rev peptide and stem IIB region of RRE. A synthetic peptide known as RSG-1.2 binds with high binding affinity and specificity to the RRE-IIB than the Rev peptide, however the thermodynamic basis of this specificity has not yet been addressed. The present study aims to probe the thermodynamic origin of this specificity of RSG-1.2 over Rev Peptide for RRE-IIB. The temperature dependent melting studies show that RSG-1.2 binding stabilizes the RRE structure significantly (ΔT(m) = 4.3°C), in contrast to Rev binding. Interestingly the thermodynamic signatures of the binding have also been found to be different for both the peptides. At pH 7.5, RSG-1.2 binds RRE-IIB with a K(a) = 16.2±0.6×10(7) M(-1) where enthalpic change ΔH = -13.9±0.1 kcal/mol is the main driving force with limited unfavorable contribution from entropic change TΔS = -2.8±0.1 kcal/mol. A large part of ΔH may be due to specific stacking between U72 and Arg15. In contrast binding of Rev (K(a) = 3.1±0.4×10(7) M(-1)) is driven mainly by entropy (ΔH = 0 kcal/mol and TΔS = 10.2±0.2 kcal/mol) which arises from major conformational changes in the RNA upon binding.
O'Shea, J C; Hafley, G E; Greenberg, S; Hasselblad, V; Lorenz, T J; Kitt, M M; Strony, J; Tcheng, J E
2001-05-16
The Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial showed the efficacy of adjunctive, double-bolus eptifibatide therapy in reducing ischemic complications of nonurgent coronary stent implantation at 48 hours and at 30 days. To determine whether the beneficial effects of eptifibatide persist at 6 months after treatment. Follow-up study of a randomized, double-blind, placebo-controlled, crossover-permitted trial conducted from June 1999 through February 2000. Ninety-two tertiary care centers in the United States and Canada. A total of 2064 patients scheduled to undergo nonurgent percutaneous coronary intervention with stent implantation. Patients were randomly assigned to receive placebo or eptifibatide (two 180-microg/kg boluses 10 minutes apart and continuous infusion of 2.0 microg/kg per minute), started immediately before stent implantation and continued for 18 to 24 hours. Complete follow-up data were available for 988 (95.0%) of 1040 patients given eptifibatide and 977 (95.4%) of 1024 patients given placebo. Composite rates of death or myocardial infarction (MI); death, MI, or target vessel revascularization; and their individual components 6 months after enrollment, compared between the 2 groups. By 6 months, the composite end point of death or MI had occurred in 7.5% of eptifibatide-treated patients and in 11.5% of placebo-treated patients (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.47-0.84; P =.002). The composite of death, MI, or target vessel revascularization was 14.2% in eptifibatide-treated patients vs 18.3% in placebo-treated patients (HR, 0.75; 95% CI, 0.60-0.93; P =.008). Most of this benefit accrued early (<48 hours after initiation of therapy) and was maintained through 6 months. Six-month mortality in the eptifibatide group was 0.8% vs 1.4% in the placebo group (HR, 0.56; 95% CI, 0.24-1.34; P =.19) and target vessel revascularization occurred in 8.6% of the eptifibatide group vs 9.4% of
International Nuclear Information System (INIS)
Salum, Resalla; Lopes, Edison R.; Souza, Maria A.H. de
1995-01-01
Patients with IB, IIa and in initial IIb cervical cancer were randomized for combined therapy, consisting of one or two radium insertion followed by Wertheim Meigs operation performed 40 days later. We look for the early and late complications of the treatment, residual cancer after radiotherapy and survival without recurrence. The project begin in 1965 and ended in 1986. All the operations were done by one of the investigators and 116 patients were analysed. The age ranged from 21 to 75 years with an average of 4.18 years. During the operations 31 (26.72%) patients needed 1.500 cc or greater amount of blood transfusion and we have 3 iliac veins lesions. Managing the ureters, we do our best to leave the posterior fascia as intact as possible. Post operative complications ranged from minor (fever, localised pelvic infections, temporary popliteal nerve paralysis) to evisceration (3 patients) deep venous thrombosis (3 patients) and two early urinary fistulas. Late complications were seen in patients submitted to sequential teletherapy irradiation. One uretrovaginal fistula occurred 10 month after treatment, another one, 7 years later and the third one 24 years later. One patient develop hydronefrosis and enterocolite after 7.000 rads of teletherapy and another one rectovaginal fistula 13 years after initial therapy. The shortening of the vagina making impossible the intercourse was seen in 7 patients. By the histological examination, the cervix was sterilized in 73.3 % of the patients. Residual cancer was found according the original size of the tumour and the stage of the disease. Studying different combinations between the existence of residual cervical cancer with positive or negative limphnodes and making a correlation with survival, we found the critical points is to have positive cervix and [positive lymphonodes. The five years survival (life table methodology) for stage 1 lesion was 96%; stage II, 67%. At ten years survival was slighted different. With positive
Directory of Open Access Journals (Sweden)
Marcinkiewicz C
2017-05-01
Full Text Available Cezary Marcinkiewicz,1,2 Jonathan A Gerstenhaber,1 Mark Sternberg,2 Peter I Lelkes,1 Giora Feuerstein1,2 1Department of Bioengineering, College of Engineering, Temple University, Philadelphia, 2Debina Diagnostic, Inc., Newton Square, PA, USA Abstract: Thromboembolic events (TEE underwrite key causes of death in developed countries. While advanced imaging technologies such as computed tomography scans serve to diagnose blood clots during acute cardiovascular events, no such technology is available in routine primary care for TEE risk assessment. Here, we describe an imaging platform technology based on bioengineered fluorescent nanodiamond particles (F-NDPs functionalized with bitistatin (Bit, a disintegrin that specifically binds to the αIIbβ3 integrin, platelet fibrinogen receptor (PFR on activated platelets. Covalent linkage of purified Bit to F-NDP was concentration-dependent and saturable, as validated by enzyme-linked immunosorbent assay using specific anti-Bit antibodies. F-NDP–Bit interacted with purified PFR, either in immobilized or soluble form. Lotrafiban, a nonpeptide, αIIbβ3 receptor antagonist, specifically blocked F-NDP–Bit–PFR complex formation. Moreover, F-NDP–Bit specifically binds to activated platelets incorporated into a clot generated by thrombin-activated rat platelet-rich plasma (PRP. Our results suggest that engineered F-NDP–Bit particles could serve as noninvasive, “real-time” optical diagnostics for clots present in blood vessels. Keywords: carbon nanoparticles, blood clots, imaging, platelet fibrinogen receptor, fluorescence, disintegrin, thromboembolic complications, thrombosis
Sills, E S; Palermo, G D
2016-03-28
While contraindications to Essure® placement have been provided by the manufacturer, there is no consensus on how best to remove these contraceptive devices. Here, we describe a non-hysterectomy removal of Essure® for a patient with a septate uterus (ESHRE Class IIb uterine malformation). A 35yr old G4 P2 presented for removal of Essure® implants after three years of gradually increasing pelvic pain, weight gain, headache, dizziness, lower extremity paresthesia, and fatigue which followed hysteroscopic sterilization (HS). Prior to HS, the patient was in good general health. She did not smoke and had never had a miscarriage. HS was performed under general anesthesia in October 2012. HSG obtained three months later, confirmed bilateral tubal occlusion but revealed an abnormal uterine cavity. A repeat HSG in 2015 showed minimal device migration, no contrast dye spill and a deeply bifid uterine cavity. At our center laparoscopic cornual dissection and bilateral partial tubal resection achieved removal of both devices intact and the patient was discharged three hours after surgery. Her postoperative recovery was uneventful. The presence of a Müllerian anomaly is a relative contraindication to the Essure® procedure. This is the first reported description of successful removal of Essure® coils in the setting of an ESHRE Class IIb uterine anomaly, and underscores the importance of careful patient selection, accurate pre-operative imaging and a conservative technique which renders hysterectomy unnecessary.
Marcinkiewicz, Cezary; Gerstenhaber, Jonathan A; Sternberg, Mark; Lelkes, Peter I; Feuerstein, Giora
2017-01-01
Thromboembolic events (TEE) underwrite key causes of death in developed countries. While advanced imaging technologies such as computed tomography scans serve to diagnose blood clots during acute cardiovascular events, no such technology is available in routine primary care for TEE risk assessment. Here, we describe an imaging platform technology based on bioengineered fluorescent nanodiamond particles (F-NDPs) functionalized with bitistatin (Bit), a disintegrin that specifically binds to the α IIb β 3 integrin, platelet fibrinogen receptor (PFR) on activated platelets. Covalent linkage of purified Bit to F-NDP was concentration-dependent and saturable, as validated by enzyme-linked immunosorbent assay using specific anti-Bit antibodies. F-NDP-Bit interacted with purified PFR, either in immobilized or soluble form. Lotrafiban, a nonpeptide, α IIb β 3 receptor antagonist, specifically blocked F-NDP-Bit-PFR complex formation. Moreover, F-NDP-Bit specifically binds to activated platelets incorporated into a clot generated by thrombin-activated rat platelet-rich plasma (PRP). Our results suggest that engineered F-NDP-Bit particles could serve as noninvasive, "real-time" optical diagnostics for clots present in blood vessels.
Puolakkainen, Tero; Ma, Hongqian; Kainulainen, Heikki; Pasternack, Arja; Rantalainen, Timo; Ritvos, Olli; Heikinheimo, Kristiina; Hulmi, Juha J; Kiviranta, Riku
2017-01-19
Inhibition of activin/myostatin pathway has emerged as a novel approach to increase muscle mass and bone strength. Duchenne muscular dystrophy (DMD) is a neuromuscular disorder that leads to progressive muscle degeneration and also high incidence of fractures. The aim of our study was to test whether inhibition of activin receptor IIB ligands with or without exercise could improve bone strength in the mdx mouse model for DMD. Thirty-two mdx mice were divided to running and non-running groups and to receive either PBS control or soluble activin type IIB-receptor (ActRIIB-Fc) once weekly for 7 weeks. Treatment of mdx mice with ActRIIB-Fc resulted in significantly increased body and muscle weights in both sedentary and exercising mice. Femoral μCT analysis showed increased bone volume and trabecular number (BV/TV +80%, Tb.N +70%, P treatment of mdx mice with the soluble ActRIIB-Fc results in a robust increase in bone mass, without any additive effect by voluntary running. Thus ActRIIB-Fc could be an attractive option in the treatment of musculoskeletal disorders.
Tsume, Yasuhiro; Matsui, Kazuki; Searls, Amanda L; Takeuchi, Susumu; Amidon, Gregory E; Sun, Duxin; Amidon, Gordon L
2017-05-01
The development of formulations and the assessment of oral drug absorption for Biopharmaceutical Classification System (BCS) class IIb drugs is often a difficult issue due to the potential for supersaturation and precipitation in the gastrointestinal (GI) tract. The physiological environment in the GI tract largely influences in vivo drug dissolution rates of those drugs. Thus, those physiological factors should be incorporated into the in vitro system to better assess in vivo performance of BCS class IIb drugs. In order to predict oral bioperformance, an in vitro dissolution system with multiple compartments incorporating physiologically relevant factors would be expected to more accurately predict in vivo phenomena than a one-compartment dissolution system like USP Apparatus 2 because, for example, the pH change occurring in the human GI tract can be better replicated in a multi-compartmental platform. The Gastrointestinal Simulator (GIS) consists of three compartments, the gastric, duodenal and jejunal chambers, and is a practical in vitro dissolution apparatus to predict in vivo dissolution for oral dosage forms. This system can demonstrate supersaturation and precipitation and, therefore, has the potential to predict in vivo bioperformance of oral dosage forms where this phenomenon may occur. In this report, in vitro studies were performed with dipyridamole and ketoconazole to evaluate the precipitation rates and the relationship between the supersaturation levels and oral absorption of BCS class II weak base drugs. To evaluate the impact of observed supersaturation levels on oral absorption, a study utilizing the GIS in combination with mouse intestinal infusion was conducted. Supersaturation levels observed in the GIS enhanced dipyridamole and ketoconazole absorption in mouse, and a good correlation between their supersaturation levels and their concentration in plasma was observed. The GIS, therefore, appears to represent in vivo dissolution phenomena and
DEFF Research Database (Denmark)
Jastaniyah, Noha; Yoshida, Kenji; Tanderup, Kari
2016-01-01
PURPOSE: To quantify the gross tumor volume at diagnosis (GTVD) and high-risk clinical target volume (CTVHR) at brachytherapy (BT) and describe subgroups of patients with different patterns of response to chemoradiotherapy (CRT) in patients with FIGO stage IIB and IIIB cervical cancer treated wit...
2013-01-01
Background A phase II clinical trial previously evaluated the sequential administration of erlotinib after chemotherapy for advanced non-small-cell lung cancer (NSCLC). This current pilot study assessed the feasibility of sequential induction therapy in patients with stage IIB to IIIA NSCLC adenocarcinoma. Methods Patients received gemcitabine 1,250 mg/m2 on days 1 and 8 and cisplatin 75 mg/m2 on day 1, followed by oral icotinib (125 mg, three times a day) on days 15 to 28. A repeatcomputed tomography(CT) scan evaluated the response to the induction treatment after two 4-week cycles and eligible patients underwent surgical resection. The primary objective was to assess the objective response rate (ORR), while EGFR and KRAS mutations and mRNA and protein expression levels of ERCC1 and RRM1 were analyzed in tumor tissues and blood samples. Results Eleven patients, most with stage IIIA disease, completed preoperative treatment. Five patients achieved partial response according to the Response Evaluation Criteria in Solid Tumors (RECIST) criteria (ORR=45%) and six patients underwent resection. Common toxicities included neutropenia, alanine transaminase (ALT) elevation, fatigue, dry skin, rash, nausea, alopecia and anorexia. No serious complications were recorded perioperatively. Three patients had exon 19 deletions and those with EGFR mutations were more likely to achieve a clinical response (P= 0.083). Furthermore, most cases who achieved a clinical response had low levels of ERCC1 expression and high levels of RRM1. Conclusions Two cycles of sequentially administered gemcitabine/cisplatin with icotinib as an induction treatment is a feasible and efficacious approach for stage IIB to IIIA NSCLC adenocarcinoma, which provides evidence for the further investigation of these chemotherapeutic and molecularly targeted therapies. PMID:23621919
Bye, Alexander P; Unsworth, Amanda J; Vaiyapuri, Sakthivel; Stainer, Alexander R; Fry, Michael J; Gibbins, Jonathan M
2015-11-01
Ibrutinib is an irreversible Bruton tyrosine kinase inhibitor approved for treatment of Waldenstrom macroglobulinemia, chronic lymphocytic leukemia, and mantle cell lymphoma that increases the risk of bleeding among patients. Platelets from ibrutinib-treated patients exhibit deficiencies in collagen-evoked signaling in suspension; however, the significance of this observation and how it relates to bleeding risk is unclear, as platelets encounter immobile collagen in vivo. We sought to clarify the effects of ibrutinib on platelet function to better understand the mechanism underlying bleeding risk. By comparing signaling in suspension and during adhesion to immobilized ligands, we found that the collagen signaling deficiency caused by ibrutinib is milder during adhesion to immobilized collagen. We also found that platelets in whole blood treated with ibrutinib adhered to collagen under arterial shear but formed unstable thrombi, suggesting that the collagen signaling deficiency caused by ibrutinib may not be the predominant cause of bleeding in vivo. However, clot retraction and signaling evoked by platelet adhesion to immobilized fibrinogen were also inhibited by ibrutinib, indicating that integrin αIIbβ3 outside-in signaling is also effected in addition to GPVI signaling. When ibrutinib was combined with the P2Y12 inhibitor, cangrelor, thrombus formation under arterial shear was inhibited additively. These findings suggest that (1) ibrutinib causes GPVI and integrin αIIbβ3 platelet signaling deficiencies that result in formation of unstable thrombi and may contribute toward bleeding observed in vivo and (2) combining ibrutinib with P2Y12 antagonists, which also inhibit thrombus stability, may have a detrimental effect on hemostasis. © 2015 American Heart Association, Inc.
Puma, Joseph A; Banko, Lesan T; Pieper, Karen S; Sacchi, Terrence J; O'Shea, J Conor; Dery, Jean Pierre; Tcheng, James E
2006-02-21
In order to determine a differential benefit from treatment, we compared the long-term outcome of high-risk versus low-risk patients and evaluated survival free from death or myocardial infarction at one year. Newer anticoagulant strategies during percutaneous coronary intervention have necessitated a reanalysis of the role of intravenous GP IIb/IIIa inhibitors. The Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy trial randomized 2,064 patients undergoing nonurgent coronary stent implantation to eptifibatide or placebo. High-risk characteristics were defined as age >75 years, diabetes, elevated cardiac markers, ST-segment elevation myocardial infarction within 7 days, or unstable angina within 48 h of randomization. Age <5 years, absence of diabetes, and any other reason for admission were considered low risk characterstics. There were 1,018 patients in the high-risk group (50.8% eptifibatide, 49.2% placebo) and 1,045 patients in the low-risk group (50.0% eptifibatide, 50.0% placebo). Baseline demographics were similar in both groups except for more hypertension (63% vs. 55%, respectively), peripheral vascular disease (8.2% vs. 5.2%, respectively), prior stroke (5.5% vs. 3.2%, respectively), and female gender (33% vs. 22%, respectively) in the high-risk than the low-risk group. At one year, the composite end point of death or myocardial infarction occurred in 15.89% of placebo patients and 7.99% of eptifibatide patients in the high-risk group and 9.02% of the placebo and 8.11% of eptifibatide patients in the low-risk group. Although eptifibatide treatment improved outcomes for all patients, preprocedural clinical characteristics can define a subgroup of patients who may derive greatest benefit from its use during coronary stent placement.
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M. Modares Gilani
2004-06-01
Full Text Available The purpose of this study was to describe the feasibility of a combined preoperative chemoradiation program Ib-IIa, bulky and suspicious IIb by radical surgery in patients with stage Ib-IIb cervical cancer. From September 1999 to April 2002, 30 patients with carcinoma of the cervix were treated with preoperative external beam radiotherapy of 45 Gy in 5 weeks. Patients received concurrent continuous infusion of cisplatin 50 mg/m2 for one day in week during 5 weeks of radiation. Radical surgery was performed 4-6 weeks after completion of the preoperative treatment. Toxicity with chemoradiation was usually mild. Two patients developed vesicovaginal fistula, and four developed long-term hydronephrosis that needed ureteral stenting. Clinical response was observed in 100% of the patients (23.7% complete response. The analysis of the surgical specimens revealed complete pathological response in 43.3% of the cases and partial pathological response in 56.7%. The degree of pathological response was not predictable by the degree of clinical response. Thirty months disease-free survival and overall survival were 66.3% and 77.31%, respectively. Patients with complete and partial pathological response were not significantly different in terms of disease-free survival (p= 0.08 and overall survival (p= 0.3. Cisplatin in preoperative chemoradiation is effective and usually welltolerated in bulky cervical cancer and parametrial invasion, inducing a high rate of clinical and pathological complete responses. When this therapy is followed by radical surgery, disease-free and overall survival rates are higher. The latter may be possible only through extensive surgical resection with a parallel increase in complication rates.
International Nuclear Information System (INIS)
Milisavljevic, Dan; Margutti, Raffaella; Soderberg, Alicia M.; Chomiuk, Laura; Sanders, Nathan E.; Pignata, Giuliano; Bufano, Filomena; Fesen, Robert A.; Parrent, Jerod T.; Parker, Stuart; Mazzali, Paolo; Pian, Elena; Pickering, Timothy; Buckley, David A. H.; Crawford, Steven M.; Gulbis, Amanda A. S.; Hettlage, Christian; Hooper, Eric; Nordsieck, Kenneth H.; O'Donoghue, Darragh
2013-01-01
We present X-ray, UV/optical, and radio observations of the stripped-envelope, core-collapse supernova (SN) 2011ei, one of the least luminous SNe IIb or Ib observed to date. Our observations begin with a discovery within ∼1 day of explosion and span several months afterward. Early optical spectra exhibit broad, Type II-like hydrogen Balmer profiles that subside rapidly and are replaced by Type Ib-like He-rich features on a timescale of one week. High-cadence monitoring of this transition suggests absorption attributable to a high-velocity (∼> 12, 000 km s –1 ) H-rich shell, which is likely present in many Type Ib events. Radio observations imply a shock velocity of v ≈ 0.13 c and a progenitor star average mass-loss rate of M-dot ∼1.4×10 -5 M sun yr -1 (assuming wind velocity v w = 10 3 km s –1 ). This is consistent with independent constraints from deep X-ray observations with Swift-XRT and Chandra. Overall, the multi-wavelength properties of SN 2011ei are consistent with the explosion of a lower-mass (3-4 M ☉ ), compact (R * ∼ 11 cm), He-core star. The star retained a thin hydrogen envelope at the time of explosion, and was embedded in an inhomogeneous circumstellar wind suggestive of modest episodic mass loss. We conclude that SN 2011ei's rapid spectral metamorphosis is indicative of time-dependent classifications that bias estimates of the relative explosion rates for Type IIb and Ib objects, and that important information about a progenitor star's evolutionary state and mass loss immediately prior to SN explosion can be inferred from timely multi-wavelength observations.
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Milisavljevic, Dan; Margutti, Raffaella; Soderberg, Alicia M.; Chomiuk, Laura; Sanders, Nathan E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Pignata, Giuliano; Bufano, Filomena [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile); Fesen, Robert A.; Parrent, Jerod T. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Lab, Hanover, NH 03755 (United States); Parker, Stuart [Parkdale Observatory, 225 Warren Road, RDl Oxford, Canterbury 7495 (New Zealand); Mazzali, Paolo [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Strasse 1, D-85748 Garching (Germany); Pian, Elena [Kavli Institute for Theoretical Physics, Kohn Hall, University of California at Santa Barbara, Santa Barbara, CA 93106-4030 (United States); Pickering, Timothy; Buckley, David A. H.; Crawford, Steven M.; Gulbis, Amanda A. S.; Hettlage, Christian [South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa); Hooper, Eric; Nordsieck, Kenneth H. [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States); O' Donoghue, Darragh, E-mail: dmilisav@cfa.harvard.edu [Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town (South Africa); and others
2013-04-10
We present X-ray, UV/optical, and radio observations of the stripped-envelope, core-collapse supernova (SN) 2011ei, one of the least luminous SNe IIb or Ib observed to date. Our observations begin with a discovery within {approx}1 day of explosion and span several months afterward. Early optical spectra exhibit broad, Type II-like hydrogen Balmer profiles that subside rapidly and are replaced by Type Ib-like He-rich features on a timescale of one week. High-cadence monitoring of this transition suggests absorption attributable to a high-velocity ({approx}> 12, 000 km s{sup -1}) H-rich shell, which is likely present in many Type Ib events. Radio observations imply a shock velocity of v Almost-Equal-To 0.13 c and a progenitor star average mass-loss rate of M-dot {approx}1.4 Multiplication-Sign 10{sup -5} M{sub sun} yr{sup -1} (assuming wind velocity v{sub w} = 10{sup 3} km s{sup -1}). This is consistent with independent constraints from deep X-ray observations with Swift-XRT and Chandra. Overall, the multi-wavelength properties of SN 2011ei are consistent with the explosion of a lower-mass (3-4 M{sub Sun }), compact (R{sub *} {approx}< 1 Multiplication-Sign 10{sup 11} cm), He-core star. The star retained a thin hydrogen envelope at the time of explosion, and was embedded in an inhomogeneous circumstellar wind suggestive of modest episodic mass loss. We conclude that SN 2011ei's rapid spectral metamorphosis is indicative of time-dependent classifications that bias estimates of the relative explosion rates for Type IIb and Ib objects, and that important information about a progenitor star's evolutionary state and mass loss immediately prior to SN explosion can be inferred from timely multi-wavelength observations.
International Nuclear Information System (INIS)
Hassan, S.F.; Wadia, S.R.
1998-02-01
We study the hypermultiplet moduli space of an N=4, U(Q 1 ) x U(Q 5 ) gauge theory in 1 + 1 dimensions to extract the effective SCFT description of near extremal 5-dimensional black holes modelled by a collection D1- and D5-branes. On the moduli space, excitations with fractional momenta arise due to a residual discrete gauge invariance. It is argued that, in the infra-red, the lowest energy excitations are described by an effective c = 6, N = 4 SCFT on T 4 , also valid in the large black hole regime. The ''effective string tension'' is obtained using T-duality covariance. While at the microscopic level, minimal scalars do not couple to (1,5) strings, in the effective theory a coupling is induced by (1,1) and (5,5) strings, leading to Hawking radiation. These considerations imply that, at least for such black holes, the calculation of the Hawking decay rate for minimal scalars has a sound foundation in string theory and statistical mechanics and, hence, there is no information loss. (author)
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Ferrigno, Robson; Faria, S.L.C.O.
1996-01-01
Purpose/Objective: To compare one and two intracavitary brachytherapy with low dose rate in the management of stage IIB cervix cancer through a prospective and randomized trial. Materials and Methods: From September 1989 to December 1992, 81 patients with stage IIB cervix cancer were randomized in two arms according to the number of intracavitary brachytherapy insertion to be realized. Of these, 34 were treated by two intracavitary insertions (group A) and 47 by one insertion (group B). The external beam radiotherapy (EBRT) was realized through a Cobalt unit at whole pelvis with total dose of 40Gy in 20 fractions of 2,0Gy, in box arrangement, followed by parametrial complementation of 10Gy. The brachytherapy was realized right after the end of EBRT. The patients from group A were underwent to two insertions of 25Gy, calculated at point A, defined by the Manchester system. The interval between each insertions was 2 weeks. The patients from group B were underwent to one insertion of 40 Gy at point A. The average dose rate was 60cGy per hour at point A. Results: With the follow up ranging from 36 to 75 months and medium of 55 months, the disease free survival of the patients from group A was not statistically different of those from group B, 70,6% and 72,3% respectively (p=0,711). Local recurrence occurred in four patients from group A (11,7%) and in eight from group B (17%). Distant metastasis occurred in one patient from group A (2,9%) and in two from group B (4,2%). Three patients from group A (8,8%) and three from group B (6,4%) were lost to follow up and considered as dead. The causes of death among patients from group A were progression of local disease in four, distant metastasis in one, complicated diabetes mellitus in one and actinic intestinal complications in other one. The cause of deaths among patients from group B were progression of local disease in eight and distant metastasis in two. The grade I and II rectal complications rate was 5,9% and 6,3% at
International Nuclear Information System (INIS)
Ferrigno, Robson; Trippe, N; Novaes, P.E.; Brandani, I.B.; Hanriot, R.; Souza, L.M.; Pellizzon, A.C.; Salvajoli, J.V.; Baraldi, H.E.; Maia, M.A.; Fogaroli, R.C.
1996-01-01
Purpose/Objective: To evaluate the histological specimens of the stage IIB cervix cancer patients who were treated by preoperative radiotherapy with external beam radiotherapy (EBRT) and high dose rate (HDR) brachytherapy. Materials and Methods: From August 1992 to August 1995, 32 patients with stage IIB cervix cancer were underwent to preoperative radiotherapy. All patients received EBRT at the whole pelvis with total dose of 45Gy in 25 fractions of 1,8Gy through a 4 MV linear accelerator. The HDR brachytherapy was realized through a Micro-Selectron device, working with Iridium-192 with initial activity of 10 Ci. The prescribed dose was 6,0Gy at point A, defined by the Manchester, system in 2 weekly insertions during the course of EBRT. The insertions were done by the Fletcher colpostats in association with intrauterine tandem. Four to six weeks after the end of radiotherapy, the patients were underwent to Total Hysterectomy and Salpingoforectomy through Piver second level technique. The uterine specimens were histologically analysed with attention to residual disease at the cervix and lymph nodes status. Results: The histological analysis showed that 19 (59,4%) patients had no residual tumor at the cervix while 13 (40,6%) had microscopic residual tumor. The lymph nodes were negative in 30 (93,8%) patients and positive in 2 (6,3%). All positive lymph nodes patients also had microscopic residual tumor at the cervix. With the follow up ranging from six to 42 months and medium of 21 months, 29 (90,6%) patients are alive with no evidence of disease, one (5,6%) is alive with local recurrence and two (6,2%) have died due to the progression of local disease. Of the 19 patients with negative specimens, 18 (94,7%) are alive with no evidence of disease and of the 13 patients with positive specimens, 11 (84,6%) are alive with no evidence of disease. Local recurrence occurred in two patients with positive specimens and in one with negative. These differences are not
International Nuclear Information System (INIS)
Cho, C.; Gellermann, J.; Jungnickel, K.; Kuemmel, S.; Hildebrandt, B.; Wust, P
2005-01-01
Full text: Regional hyperthermia is combined with radiochemotherapy to achieve resectability in non-resectable cervical carcinoma. In a phase II study at the Charite Medical School approved by the institutionals ethical committee non-resectable cervical carcinoma of at least FIGO IIB were treated with radiochemotherapy combined with regional hyperthermia. The treatment concept comprises cisplatinum therapy of 40 mg/sqm body surface once weekly during regional hyperthermia supplementing radiation therapy of 5 x 1.8 Gy to a total dose of 45 - 50.4 Gy. A gynecological status and imaging is performed for evaluation of resectability of the tumor. If a tumor resection was not feasable radiation was completed to 59.4 - 63 Gy supplemented by 4 - 5 afterloading sessions. Regional hyperthermia was conducted with SIGMA 60 or SIGMA Eye applicator of the system BSD-2000, on average steady state temperatures between 40-41 o C were achieved over the therapeutic time. From 2000 to 2003 we recruited 30 patients. Acute toxicity was in the usual range (10-15 % grade ≥ 3). Two thirds were FIGO stage III/IV with tumor diameters > 6 cm. After treatment 20/30 (67 %) of the former inoperable cases were evaluated as resectable, 3 of these patients refused surgery. Of the remaining 17 cases 14 patients were R0-resected, 2 patients were R1-resected, and 1 patient had a positive paraaortal lymphnode. In 13/30 patients nonsurgical treatment was continued. Response was achieved in 23/30 patients (77 %), i.e. 14 resectable cases with downstaging and 9 partial remissions (PR) after hyperthermic radiochemotherapy with 45 - 50.4 Gy. Response correlated well with thermal parameters, in particular the mean temperature in the vaginal reference point. For the whole group a three year overall survival of 60 % was achieved together with a moderate late toxicity ≥ 3 in 4/30 patients (13 %). R0-resected patients have an excellent prognosis with a 3-year survival of 95 % and a late toxicity ≥ 3 below
Fatima, Bilqees; Ali, Sikander
2012-01-01
Sixteen different mould cultures viz. Aspergillus, Alternaria, Arthroderma, Trichoderma, Fusarium, Penicillium, Rhizopus and Chochliobolus were isolated from the soil samples of Qatar by serial dilution method. The preliminary screening of isolates was done by selecting initial colonies showing relatively bigger zones of starch hydrolysis on nutrient agar plates. The isolates were then subjected to secondary screening by submerged fermentation (SmF). The 1,4-α-D-glucan glucohydrolase (GGH) activity ranged from 1.906-12.675 U/ml/min. The product yield was analysed in dependence of mycelial morphology, biomass level and protein content. The isolate Aspergillus oryzae llB-6 which gave maximum enzyme production was incubated in M3 medium containing 20 g/l starch, 10 g/l lactose, 8.5 g/l yeast extract, 6 g/l corn steep liquor (CSL), 1.2 g/l MgSO4.7H2O, 1.3 g/l NH4Cl, 0.6 g/l CaCl2.2H2O, pH 5 at 30±2°C and 200 rpm. On the basis of kinetic variables, notably Qp (0.058±0.01(a) U/g/h), Yp/s (0.308±0.03(ab) U/g) and qp (0.210±0.032(abc) U/g fungal biomass/h), A. oryzae IIB-6 was found to be a hyper producer of GGH (LSD 0.0345) compared to A. kawachii IIB-2. A noticeable enhancement in enzyme activity of over 30% was observed (13.917±1.01 U/ml/min) when the process parameters viz. cultural conditions (pH 5, incubation period 72 h) and nutritional requirements (6 g/l CSL, 9.5 g/l yeast extract, 10 g/l starch, 20 g/l lactose) were further optimized using a 2-factorial Plackett-Burman design. The model terms were found to be highly significant (HS, p≤0.05), indicating the potential utility of the culture (dof~3).
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Yu Liu
2015-01-01
Full Text Available Background: Pelvic lymph node metastasis (LNM is an important prognostic factor in cervical cancer. Cervical squamous cell carcinoma accounts for approximately 75-80% of all cervical cancers. Analyses of the effects of the number of positive lymph nodes (LNs, unilateral versus bilateral pelvic LNM and a single group versus multiple groups of pelvic LNM on survival and recurrence of cervical squamous cell carcinoma are still lacking. The study aimed to analyze the effects of the number of positive pelvic LNs and a single group versus multiple groups of pelvic LNM on survival and recurrence. Methods: We performed a retrospective review of 296 patients diagnosed with Stage IA-IIB cervical squamous cell carcinoma who received extensive/sub-extensive hysterectomy with pelvic lymphadenectomy/pelvic LN sampling at Peking University People′s Hospital from November 2004 to July 2013. Ten clinicopathological variables were evaluated as risk factors for pelvic LNM: Age at diagnosis, gravidity, clinical stage, histological grade, tumor diameter, lymph-vascular space involvement (LVSI, depth of cervical stromal invasion, uterine invasion, parametrial invasion, and neoadjuvant chemotherapy. Results: The incidence of pelvic LNM was 20.27% (60/296 cases. Pelvic LNM (P = 0.00 was significantly correlated with recurrence. Pelvic LNM (P = 0.00, the number of positive pelvic LNs (P = 0.04 and a single group versus multiple groups of pelvic LNM (P = 0.03 had a significant influence on survival. Multivariate analysis revealed that LVSI (P = 0.00, depth of cervical stromal invasion (P = 0.00 and parametrial invasion (P = 0.03 were independently associated with pelvic LNM. Conclusions: Patients with pelvic LNM had a higher recurrence rate and poor survival outcomes. Furthermore, more than 2 positive pelvic LNs and multiple groups of pelvic LNM appeared to identify patients with worse survival outcomes in node-positive IA-IIB cervical squamous cell carcinoma. LVSI
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Constantin von zur Mühlen
2008-03-01
Full Text Available Recent progress in molecular magnetic resonance imaging (MRI provides the opportunity to image cells and cellular receptors using microparticles of iron oxide (MPIOs. However, imaging targets on vessel walls remains challenging owing to the quantity of contrast agents delivered to areas of interest under shear stress conditions. We evaluated ex vivo binding characteristics of a functional MRI contrast agent to ligand-induced binding sites (LIBSs on activated glycoprotein IIb/IIIa receptors of human platelets, which were lining rupture-prone atherosclerotic plaques and could therefore facilitate detection of platelet-mediated pathology in atherothrombotic disease. MPIOs were conjugated to anti-LIBS single-chain antibodies (LIBS-MPIO or control antibodies (control MPIO. Ex vivo binding to human platelet-rich clots in a dose-dependent manner was confirmed on a 3 T clinical MRI scanner and by histology (p < .05 for LIBS-MPIO vs control MPIO. By using a flow chamber setup, significant binding of LIBS-MPIO to a platelet matrix was observed under venous and arterial flow conditions, but not for control MPIO (p < .001. A newly generated MRI contrast agent detects activated human platelets at clinically relevant magnetic field strengths and binds to platelets under venous and arterial flow conditions, conveying high payloads of contrast to specific molecular targets. This may provide the opportunity to identify vulnerable, rupture-prone atherosclerotic plaques via noninvasive MRI.
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Jaeger, E; Sinzinger, H; Widhalm, K; Kaliman, J; Hoefer, R [Vienna Univ. (Austria). 2. Medizinische Klinik; Ludwig Boltzmann-Institut fuer Nuklearmedizin, Vienna (Austria); Vienna Univ. (Austria). Kinderklinik; Vienna Univ. (Austria). Kardiologische Klinik)
1982-09-01
It is generally accepted that platelet half-life is shortened in atherosclerotic vascular diseases. Concerning changes due to hyperlipoproteinemia (HLP), however, there exist only few data. Therefore, we examined the platelet-half life in 60 patients with recently discovered HLP type IIa, IIb and IV according to Fredrickson before treatment in comparison to 60 controls. 33 of the HLP-patients had no clinical symptoms of angiopathy. 27 patients suffered from peripheral vascular disease or from coronary heart disease as verified by angiography. The labelling of autologous platelets was performed with 100..mu..Ci of /sup 111/Indium-oxine-sulfate at 37/sup 0/C for 5 minutes. The mean labelling efficiency was 90%, the recovery after 2 hours about 70%. Serum lipoproteins were estimated by means of ultracentrifugation and polyanionprecipitation according to Lipid Research Clinic Methods. In the patients with HLP platelet half-life was significantly shortened in comparison to the control group (p < 0.01). These changes were most pronounced in patients with HLP-type IIa and with atherosclerotic lesions, respectively. In patients with HLP-type IIa a very close correlation could be demonstrated between platelet half-life and LDL-cholesterol (r = -0.72; p < 0.001) as well as total cholesterol (r = -0.73; p < 0.001). These data prove that in HLP in-vivo platelet function as measured by platelet survival is significantly influenced even before the occurrence of clinically relevant symptoms of atherosclerosis.
Babcock, Lyle W; Knoblauch, Mark; Clarke, Mark S F
2015-09-15
Chronic unloading induces decrements in muscle size and strength. This adaptation is governed by a number of molecular factors including myostatin, a potent negative regulator of muscle mass. Myostatin must first be secreted into the circulation and then bind to the membrane-bound activin receptor IIB (actRIIB) to exert its atrophic action. Therefore, we hypothesized that myofiber type-specific atrophy observed after hindlimb suspension (HLS) would be related to myofiber type-specific expression of myostatin and/or actRIIB. Wistar rats underwent HLS for 10 days, after which the tibialis anterior was harvested for frozen cross sectioning. Simultaneous multichannel immunofluorescent staining combined with differential interference contrast imaging was employed to analyze myofiber type-specific expression of myostatin and actRIIB and myofiber type cross-sectional area (CSA) across fiber types, myonuclei, and satellite cells. Hindlimb suspension (HLS) induced significant myofiber type-specific atrophy in myosin heavy chain (MHC) IIx (P Myostatin staining associated with myonuclei was less in HLS rats compared with controls, while satellite cell staining for myostatin remained unchanged. In contrast, the total number myonuclei and satellite cells per myofiber was reduced in HLS compared with ambulatory control rats (P myostatin-induced myofiber type-selective atrophy observed during chronic unloading. Copyright © 2015 the American Physiological Society.
Type IIB supergravity solution for the T-dual of the η-deformed AdS_5×S"5 superstring
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Hoare, B.; Tseytlin, A.A.
2015-01-01
We find an exact type IIB supergravity solution that represents a one-parameter deformation of the T-dual of the AdS_5×S"5 background (with T-duality applied in all 6 abelian bosonic isometric directions). The non-trivial fields are the metric, dilaton and RR 5-form only. The latter has remarkably simple “undeformed” form when written in terms of a “deformation-rotated” vielbein basis. An unusual feature of this solution is that the dilaton contains a linear dependence on the isometric coordinates of the metric precluding a straightforward reversal of T-duality. If we still formally dualize back, we find exactly the metric, B-field and product of dilaton with RR field strengths as recently extracted from the η-deformed AdS_5×S"5 superstring action in http://arxiv.org/abs/1507.04239. We also discuss similar solutions for deformed AdS_n×S"n backgrounds with n=2,3. In the η→i limit we demonstrate that all these backgrounds can be interpreted as special limits of gauged WZW models and are also related to (a limit of) the Pohlmeyer-reduced models of the AdS_n×S"n superstrings.
Brzoska, Tomasz; Suzuki, Yuko; Mogami, Hideo; Sano, Hideto; Urano, Tetsumei
2013-01-01
Recently, by employing intra-vital confocal microscopy, we demonstrated that platelets expose phosphatidylserine (PS) and fibrin accumulate only in the center of the thrombus but not in its periphery. To address the question how exposure of platelet anionic phospholipids is regulated within the thrombus, an in-vitro experiment using diluted platelet-rich plasma was employed, in which the fibrin network was formed in the presence of platelets, and PS exposure on the platelet surface was analyzed using Confocal Laser Scanning Microscopy. Almost all platelets exposed PS after treatment with tissue factor, thrombin or ionomycin. Argatroban abrogated fibrin network formation in all samples, however, platelet PS exposure was inhibited only in tissue factor- and thrombin-treated samples but not in ionomycin-treated samples. FK633, an αIIbβ3 antagonist, and cytochalasin B impaired platelet binding to the fibrin scaffold and significantly reduced PS exposure evoked by thrombin. Gly-Pro-Arg-Pro amide abrogated not only fibrin network formation, but also PS exposure on platelets without suppressing platelet binding to fibrin/fibrinogen. These results suggest that outside-in signals in platelets generated by their binding to the rigid fibrin network are essential for PS exposure after thrombin treatment. PMID:23383331
Brzoska, Tomasz; Suzuki, Yuko; Mogami, Hideo; Sano, Hideto; Urano, Tetsumei
2013-01-01
Recently, by employing intra-vital confocal microscopy, we demonstrated that platelets expose phosphatidylserine (PS) and fibrin accumulate only in the center of the thrombus but not in its periphery. To address the question how exposure of platelet anionic phospholipids is regulated within the thrombus, an in-vitro experiment using diluted platelet-rich plasma was employed, in which the fibrin network was formed in the presence of platelets, and PS exposure on the platelet surface was analyzed using Confocal Laser Scanning Microscopy. Almost all platelets exposed PS after treatment with tissue factor, thrombin or ionomycin. Argatroban abrogated fibrin network formation in all samples, however, platelet PS exposure was inhibited only in tissue factor- and thrombin-treated samples but not in ionomycin-treated samples. FK633, an α(IIb)β₃ antagonist, and cytochalasin B impaired platelet binding to the fibrin scaffold and significantly reduced PS exposure evoked by thrombin. Gly-Pro-Arg-Pro amide abrogated not only fibrin network formation, but also PS exposure on platelets without suppressing platelet binding to fibrin/fibrinogen. These results suggest that outside-in signals in platelets generated by their binding to the rigid fibrin network are essential for PS exposure after thrombin treatment.
Kasahara, Kohji; Kaneda, Mizuho; Miki, Toshiaki; Iida, Kazuko; Sekino-Suzuki, Naoko; Kawashima, Ikuo; Suzuki, Hidenori; Shimonaka, Motoyuki; Arai, Morio; Ohno-Iwashita, Yoshiko; Kojima, Soichi; Abe, Mitsuhiro; Kobayashi, Toshihide; Okazaki, Toshiro; Souri, Masayoshi; Ichinose, Akitada; Yamamoto, Naomasa
2013-11-07
Membrane rafts are spatially and functionally heterogenous in the cell membrane. We observed that lysenin-positive sphingomyelin (SM)-rich rafts are identified histochemically in the central region of adhered platelets where fibrin and myosin are colocalized on activation by thrombin. The clot retraction of SM-depleted platelets from SM synthase knockout mouse was delayed significantly, suggesting that platelet SM-rich rafts are involved in clot retraction. We found that fibrin converted by thrombin translocated immediately in platelet detergent-resistant membrane (DRM) rafts but that from Glanzmann's thrombasthenic platelets failed. The fibrinogen γ-chain C-terminal (residues 144-411) fusion protein translocated to platelet DRM rafts on thrombin activation, but its mutant that was replaced by A398A399 at factor XIII crosslinking sites (Q398Q399) was inhibited. Furthermore, fibrin translocation to DRM rafts was impaired in factor XIII A subunit-deficient mouse platelets, which show impaired clot retraction. In the cytoplasm, myosin translocated concomitantly with fibrin translocation into the DRM raft of thrombin-stimulated platelets. Furthermore, the disruption of SM-rich rafts by methyl-β-cyclodextrin impaired myosin activation and clot retraction. Thus, we propose that clot retraction takes place in SM-rich rafts where a fibrin-αIIbβ3-myosin complex is formed as a primary axis to promote platelet contraction.
Saunders, Stuart M; Ellis, Scott J; Demetracopoulos, Constantine A; Marinescu, Anca; Burkett, Jayme; Deland, Jonathan T
2018-01-01
The forefoot abduction component of the flexible adult-acquired flatfoot can be addressed with lengthening of the anterior process of the calcaneus. We hypothesized that the step-cut lengthening calcaneal osteotomy (SLCO) would decrease the incidence of nonunion, lead to improvement in clinical outcome scores, and have a faster time to healing compared with the traditional Evans osteotomy. We retrospectively reviewed 111 patients (143 total feet: 65 Evans, 78 SLCO) undergoing stage IIB reconstruction followed clinically for at least 2 years. Preoperative and postoperative radiographs were analyzed for the amount of deformity correction. Computed tomography (CT) was used to analyze osteotomy healing. The Foot and Ankle Outcome Scores (FAOS) and lateral pain surveys were used to assess clinical outcomes. Mann-Whitney U tests were used to assess nonnormally distributed data while χ 2 and Fisher exact tests were used to analyze categorical variables (α = 0.05 significant). The Evans group used a larger graft size ( P lengthening. Level III, retrospective cohort study.
Warped AdS{sub 6}×S{sup 2} in Type IIB supergravity II: global solutions and five-brane webs
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D’Hoker, Eric; Gutperle, Michael; Uhlemann, Christoph F. [Mani L. Bhaumik Institute for Theoretical Physics,Department of Physics and Astronomy, University of California Los Angeles,475 Portola Plaza, Los Angeles, CA 90095 (United States)
2017-05-23
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 AdS{sub 6}×S{sup 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{sub ±} 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{sub ±} for arbitrary Σ. Global solutions exist only when Σ has a non-empty boundary ∂Σ. The differentials ∂A{sub ±} 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.
Directory of Open Access Journals (Sweden)
Tomasz Brzoska
Full Text Available Recently, by employing intra-vital confocal microscopy, we demonstrated that platelets expose phosphatidylserine (PS and fibrin accumulate only in the center of the thrombus but not in its periphery. To address the question how exposure of platelet anionic phospholipids is regulated within the thrombus, an in-vitro experiment using diluted platelet-rich plasma was employed, in which the fibrin network was formed in the presence of platelets, and PS exposure on the platelet surface was analyzed using Confocal Laser Scanning Microscopy. Almost all platelets exposed PS after treatment with tissue factor, thrombin or ionomycin. Argatroban abrogated fibrin network formation in all samples, however, platelet PS exposure was inhibited only in tissue factor- and thrombin-treated samples but not in ionomycin-treated samples. FK633, an α(IIbβ₃ antagonist, and cytochalasin B impaired platelet binding to the fibrin scaffold and significantly reduced PS exposure evoked by thrombin. Gly-Pro-Arg-Pro amide abrogated not only fibrin network formation, but also PS exposure on platelets without suppressing platelet binding to fibrin/fibrinogen. These results suggest that outside-in signals in platelets generated by their binding to the rigid fibrin network are essential for PS exposure after thrombin treatment.
Sanchez, Larysa; Vesole, David H; Richter, Joshua R; Biran, Noa; Bilotti, Elizabeth; McBride, Laura; Anand, Palka; Ivanovski, Kristin; Siegel, David S
2017-02-01
Clinical trials of vorinostat, a Class I/II histone deacetylase inhibitor, in combination with proteasome inhibitors and immunomodulatory agents have shown activity in relapsed/refractory multiple myeloma. This phase IIb, open-label, single-institution study evaluated the efficacy of vorinostat in combination with lenalidomide and dexamethasone in lenalidomide-refractory patients. Patients were considered lenalidomide-refractory if they had no clinical response (vorinostat 400 mg days 1-7 and 15-21, lenalidomide 25 mg days 1-21, and dexamethasone 40 mg days 1, 8, 15 and 22 in 28-day cycles. Twenty-five patients were enrolled, median age was 65 years and patients had received a median of 5 prior regimens. The overall response rate was 24% (6 partial responses) and clinical benefit rate (≥stable disease) was 80%. Median time to a partial response was 1·9 months and median duration of response was 3·3 months. Median progression-free survival was 5·3 months. Most common grade 3/4 adverse events were neutropenia (48%), thrombocytopenia (32%), anaemia (20%) and gastrointestinal toxicities (16%). In this heavily pre-treated population, vorinostat in combination with lenalidomide and dexamethasone was active in lenalidomide-refractory patients. © 2016 John Wiley & Sons Ltd.
Lonsdorf, Anke S.; Krämer, Björn F.; Fahrleitner, Manuela; Schönberger, Tanja; Gnerlich, Stephan; Ring, Sabine; Gehring, Sarah; Schneider, Stefan W.; Kruhlak, Michael J.; Meuth, Sven G.; Nieswandt, Bernhard; Gawaz, Meinrad; Enk, Alexander H.; Langer, Harald F.
2012-01-01
A mutual relationship exists between metastasizing tumor cells and components of the coagulation cascade. The exact mechanisms as to how platelets influence blood-borne metastasis, however, remain poorly understood. Here, we used murine B16 melanoma cells to observe functional aspects of how platelets contribute to the process of hematogenous metastasis. We found that platelets interfere with a distinct step of the metastasis cascade, as they promote adhesion of melanoma cells to the endothelium in vitro under shear conditions. Constitutively active platelet receptor GPIIb/IIIa (integrin αIIbβ3) expressed on Chinese hamster ovary cells promoted melanoma cell adhesion in the presence of fibrinogen, whereas blocking antibodies to aνβ3 integrin on melanoma cells or to GPIIb/IIIa significantly reduced melanoma cell adhesion to platelets. Furthermore, using intravital microscopy, we observed functional platelet-melanoma cell interactions, as platelet depletion resulted in significantly reduced melanoma cell adhesion to the injured vascular wall in vivo. Using a mouse model of hematogenous metastasis to the lung, we observed decreased metastasis of B16 melanoma cells to the lung by treatment with a mAb blocking the aν subunit of aνβ3 integrin. This effect was significantly reduced when platelets were depleted in vivo. Thus, the engagement of GPIIb/IIIa with aνβ3 integrin interaction mediates tumor cell-platelet interactions and highlights how this interaction is involved in hematogenous tumor metastasis. PMID:22102277
Directory of Open Access Journals (Sweden)
Hélène Froquet
2008-06-01
Full Text Available Un diagnostic archéologique réalisé en 2004 à Sandillon (Loiret a permis la découverte d’une occupation du Bronze final IIb dans la plaine alluviale de la Loire. Les structures sont peu nombreuses, mais une fosse se distingue par un ensemble céramique exceptionnel par sa richesse, sa conservation et la présence de formes encore inconnues en région Centre. Ce corpus céramique, corrélé par une datation par radiocarbone, offre désormais un jalon fiable pour la région. Par ailleurs, ces vestiges ont pu être replacés dans leur environnement immédiat grâce à une étude géomorphologique et à l’analyse des restes carpologiques contenus dans la fosse. Ainsi, le croisement des données permet de tenter une approche paléo environnementale sur une occupation en contexte fluviatile et de préciser les relations entre l’homme et son milieu durant cette période chronologique.An archaeological diagnostic carried out in 2004 at Sandillon (Loiret enabled the discovery of a final Bronze Age IIb occupation in the alluvial Loire valley. There are few structures but one pit is noteworthy for a ceramic collection, exceptional in its abundance, its preservation and the presence of previously unknown forms in the Centre region. This ceramic corpus, dated by radiocarbon, henceforth provides a reliable standard for the region. Moreover, these relics could be set in their immediate environment thanks to a geomorphological study and to the analysis of carpological remains contained in the pit. So, the crossing of data allows us to attempt an environmental paleolithic approach to an occupation in a freshwater context and to clarify the relationship between man and his environment in this chronological period.
The mirror transform of type I vacua in six dimensions
International Nuclear Information System (INIS)
Sen, A.; Sethi, S.
1997-01-01
We study certain compactifications of the type I string on K3. The three topologically distinct choices of gauge bundles for the type I theory are shown to be equivalent to type IIB orientifolds with different choices of background anti-symmetric tensor field flux. Using a mirror transformation we relate these models to orientifolds with fixed seven planes, and without any anti-symmetric tensor field flux. This map allows us to relate these type I vacua to particular six-dimensional F-theory and heterotic string compactifications. (orig.)
International Nuclear Information System (INIS)
Blumenhagen, Ralph; Jurke, Benjamin; Grimm, Thomas W.; Weigand, Timo
2009-01-01
We study the F-theory uplift of Type IIB orientifold models on compact Calabi-Yau threefolds containing divisors which are del Pezzo surfaces. We consider two examples defined via del Pezzo transitions of the quintic. The first model has an orientifold projection leading to two disjoint O7-planes and the second involution acts via an exchange of two del Pezzo surfaces. The two uplifted fourfolds are generically singular with minimal gauge enhancements over a divisor and, respectively, a curve in the non-Fano base. We study possible further degenerations of the elliptic fiber leading to F-theory GUT models based on subgroups of E 8 .
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Collinucci, Andres
2009-01-01
In this note, a procedure is developed to explicitly construct non-trivial F-theory lifts of perturbative IIB orientifold models on Calabi-Yau complete intersections in toric varieties. This procedure works on Calabi-Yau orientifolds where the involution coordinate can have arbitrary projective weight, as opposed to the well-known hypersurface cases where it has half the weight of the equation defining the CY threefold. This opens up the possibility of lifting more general setups, such as models that have O3-planes.
Moduli stabilization in non-geometric backgrounds
International Nuclear Information System (INIS)
Becker, Katrin; Becker, Melanie; Vafa, Cumrun; Walcher, Johannes
2007-01-01
Type II orientifolds based on Landau-Ginzburg models are used to describe moduli stabilization for flux compactifications of type II theories from the world-sheet CFT point of view. We show that for certain types of type IIB orientifolds which have no Kaehler moduli and are therefore intrinsically non-geometric, all moduli can be explicitly stabilized in terms of fluxes. The resulting four-dimensional theories can describe Minkowski as well as anti-de Sitter vacua. This construction provides the first string vacuum with all moduli frozen and leading to a 4D Minkowski background
Bradford, Seth S; Ross, Martin James; Fidai, Insiya; Cowan, James A
2014-06-01
The complex Cu-GGHYrFK-amide (1-Cu) was previously reported as a novel metallotherapeutic that catalytically inactivates stem loop IIb (SLIIb) of the hepatitis C virus (HCV) internal ribosomal entry site (IRES) RNA and demonstrates significant antiviral activity in a cellular HCV replicon assay. Herein we describe additional studies focused on understanding the cleavage mechanism as well as the relationship of catalyst configuration to structural recognition and site-selective cleavage of the structured RNA motif. These are advanced by use of a combination of MALDI-TOF mass spectrometry, melting temperature determinations, and computational analysis to develop a structural model for binding and reactivity toward SLIIb of the IRES RNA. In addition, the binding, reactivity, and structural chemistry of the all-D-amino acid form of this metallopeptide, complex 2-Cu, are reported and compared with those of complex 1-Cu. In vitro RNA binding and cleavage assays for complex 2-Cu show a KD value of 76 ± 3 nM, and Michaelis-Menten parameters of kcat =0.14 ± 0.01 min(-1) and KM =7.9 ± 1.2 μM, with a turnover number exceeding 40. In a luciferase-based cellular replicon assay Cu-GGhyrfk-amide shows activity similar to that of the 1-Cu parent peptide, with an IC50 value of 1.9 ± 0.4 μM and cytotoxicity exceeding 100 μM. RT-PCR experiments confirm a significant decrease in HCV RNA levels in replicon assays for up to nine days when treated with complex 1-Cu in three-day dosing increments. This study shows the influence that the α-carbon stereocenter has for this new class of compounds, while detailed mass spectrometry and computational analyses provide new insight into the mechanisms of recognition, binding, and reactivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Escamilla-Martínez, E E; Cisneros, Y M Álvarez; Fernández, F J; Quirasco-Baruch, M; Ponce-Alquicira, E
2017-10-09
The Enterococcus faecium strain MXVK29, isolated from fermented sausages, produces a bacteriocin with a molecular mass of 3.5 kDa that belongs to the class of enterocins II.1, according to the terminal amino acid sequence, and has been identified as enterocin A. This bacteriocin is active against selected strains of Listeria, Staphylococcus, Pediococcus, and Enterococcus. In this study, we identified the genes adjacent to the structural gene for this bacteriocin, such as the immunity gene (entI) and the inducer gene (entF). Accessory genes for this bacteriocin, such as entK, entR, and entT, were identified as well, in addition to the orf2 and orf3, showing a high identity with class IIb peptides bacteriocins. The orf2 shows the consensus motif GxxxG, similar to those shown by bacteriocins such as PlnNC8α, EntCα, and Ent1071A, whereas orf3 shows a consensus motif SxxxS similar to that present in PlnNC8β (AxxxA). PlnNC8 is expressed only in bacterial cocultures, so there is the possibility that the expression of this two-peptide bacteriocin can be induced by a similar mechanism. So far, only the expression of enterocin A has been found in this strain; however, the presence of the genes ent29α and ent29β opens the possibility for further research on its induction, functionality, and origin. Although there are reports on this type of bacteriocin (EntX, EntC, and Ent1071) in other strains of E. faecium, no report exists yet on an Enterococcus strain producing two different classes of bacteriocin.
Hecht, J Randolph; Mitchell, Edith P; Yoshino, Takayuki; Welslau, Manfred; Lin, Xun; Chow Maneval, Edna; Paolini, Jolanda; Lechuga, Maria Jose; Kretzschmar, Albrecht
2015-01-01
Background Sunitinib is an oral inhibitor of tyrosine kinase receptors implicated in tumor proliferation, angiogenesis, and metastasis. In this randomized, multicenter, open-label Phase IIb study, sunitinib plus mFOLFOX6 (oxaliplatin plus leucovorin plus 5-fluorouracil) was compared with bevacizumab plus mFOLFOX6 as first-line therapy in patients with metastatic colorectal cancer. Methods Patients were stratified by performance status, baseline lactate dehydrogenase level, and prior adjuvant treatment, and randomized 1:1 to receive sunitinib 37.5 mg/day for 4 weeks on and 2 weeks off plus mFOLFOX6 every 2 weeks or bevacizumab 5 mg/kg every 2 weeks plus mFOLFOX6 every 2 weeks. The primary endpoint was progression-free survival. Secondary endpoints included objective response rate, overall survival, safety, and quality of life. Results Enrollment was closed early following accrual of 191 patients, based on an interim analysis showing an inferior trend in the primary progression-free survival efficacy endpoint for sunitinib. Ninety-six patients were randomized to sunitinib plus mFOLFOX6 and 95 to bevacizumab plus mFOLFOX6. Median progression-free survival was 9.3 months and 15.4 months, respectively, but the objective response rate was similar between the study arms. Median overall survival was 23.7 months and 34.1 months, respectively. Dose reductions and interruptions were more common with sunitinib. Hematologic toxicity was more common in the sunitinib arm. Conclusion While the results of the sunitinib arm are comparable with those of previously reported FOLFOX combinations, the sunitinib-based combination was associated with more toxicity than that observed with bevacizumab and mFOLFOX6. The bevacizumab arm had an unexpectedly good outcome, and was much better than that seen in the Phase III trials. Combination therapy with sunitinib plus mFOLFOX6 is not recommended for patients with metastatic colorectal cancer. PMID:26109878
International Nuclear Information System (INIS)
Hecht, J Randolph; Mitchell, Edith P; Yoshino, Takayuki; Welslau, Manfred; Lin, Xun; Chow Maneval, Edna; Paolini, Jolanda; Lechuga, Maria Jose; Kretzschmar, Albrecht
2015-01-01
Sunitinib is an oral inhibitor of tyrosine kinase receptors implicated in tumor proliferation, angiogenesis, and metastasis. In this randomized, multicenter, open-label Phase IIb study, sunitinib plus mFOLFOX6 (oxaliplatin plus leucovorin plus 5-fluorouracil) was compared with bevacizumab plus mFOLFOX6 as first-line therapy in patients with metastatic colorectal cancer. Patients were stratified by performance status, baseline lactate dehydrogenase level, and prior adjuvant treatment, and randomized 1:1 to receive sunitinib 37.5 mg/day for 4 weeks on and 2 weeks off plus mFOLFOX6 every 2 weeks or bevacizumab 5 mg/kg every 2 weeks plus mFOLFOX6 every 2 weeks. The primary endpoint was progression-free survival. Secondary endpoints included objective response rate, overall survival, safety, and quality of life. Enrollment was closed early following accrual of 191 patients, based on an interim analysis showing an inferior trend in the primary progression-free survival efficacy endpoint for sunitinib. Ninety-six patients were randomized to sunitinib plus mFOLFOX6 and 95 to bevacizumab plus mFOLFOX6. Median progression-free survival was 9.3 months and 15.4 months, respectively, but the objective response rate was similar between the study arms. Median overall survival was 23.7 months and 34.1 months, respectively. Dose reductions and interruptions were more common with sunitinib. Hematologic toxicity was more common in the sunitinib arm. While the results of the sunitinib arm are comparable with those of previously reported FOLFOX combinations, the sunitinib-based combination was associated with more toxicity than that observed with bevacizumab and mFOLFOX6. The bevacizumab arm had an unexpectedly good outcome, and was much better than that seen in the Phase III trials. Combination therapy with sunitinib plus mFOLFOX6 is not recommended for patients with metastatic colorectal cancer
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Huguet, Florence; Cojocariu, Oana-Maria; Levy, Pierre; Lefranc, Jean-Pierre; Darai, Emile; Jannet, Denis; Ansquer, Yan; Lhuillier, Pierre-Eugene; Benifla, Jean-Louis; Seince, Nathalie; Touboul, Emmanuel
2008-01-01
Purpose: To evaluate toxicity, local tumor control, and survival after preoperative chemoradiation for operable bulky cervical carcinoma. Methods and Materials: Between December 1991 and July 2006, 92 patients with operable bulky stage IB2, IIA, and IIB cervical carcinoma without pelvic or para-aortic nodes on pretreatment imaging were treated. Treatment consisted of preoperative external beam pelvic radiation therapy (EBRT) and concomitant chemotherapy (CT) during the first and fourth weeks of radiation combining 5-fluorouracil and cisplatin. The pelvic radiation dose was 40.5 Gy over 4.5 weeks. EBRT was followed by low-dose rate uterovaginal brachytherapy with a total dose of 20 Gy in 62 patients. After a median rest period of 44 days, all patients underwent Class II modified radical hysterectomy with bilateral pelvic lymphadenectomy. Thirty patients who had not received preoperative uterovaginal brachytherapy underwent postoperative low-dose-rate vaginal brachytherapy at a dose of 20 Gy. The mean follow-up was 46 months. Results: Pathologic residual tumor was observed in 43 patients. After multivariate analysis, additional preoperative uterovaginal brachytherapy was the single significant predictive factor for pathologic complete response rate (p = 0.019). The 2- and 5-year disease-free survival (DFS) rates were 80.4% and 72.2%, respectively. Pathologic residual cervical tumor was the single independent factor decreasing the probability of DFS (p = 0.020). Acute toxicities were moderate. Two severe ureteral complications requiring surgical intervention were observed. Conclusions: Concomitant chemoradiation followed by surgery for operable bulky stage I-II cervical carcinoma without clinical lymph node involvement can be used with acceptable toxicity. Pathologic complete response increases the probability of DFS
Schwartzberg, Lee S; Yardley, Denise A; Elias, Anthony D; Patel, Manish; LoRusso, Patricia; Burris, Howard A; Gucalp, Ayca; Peterson, Amy C; Blaney, Martha E; Steinberg, Joyce L; Gibbons, Jacqueline A; Traina, Tiffany A
2017-08-01
Purpose: Several lines of evidence support targeting the androgen signaling pathway in breast cancer. Enzalutamide is a potent inhibitor of androgen receptor signaling. Preclinical data in estrogen-expressing breast cancer models demonstrated activity of enzalutamide monotherapy and enhanced activity when combined with various endocrine therapies (ET). Enzalutamide is a strong cytochrome P450 3A4 (CYP3A4) inducer, and ETs are commonly metabolized by CYP3A4. The pharmacokinetic (PK) interactions, safety, and tolerability of enzalutamide monotherapy and in combination with ETs were assessed in this phase I/Ib study. Experimental Design: Enzalutamide monotherapy was assessed in dose-escalation and dose-expansion cohorts of patients with advanced breast cancer. Additional cohorts examined effects of enzalutamide on anastrozole, exemestane, and fulvestrant PK in patients with estrogen receptor-positive/progesterone receptor-positive (ER + /PgR + ) breast cancer. Results: Enzalutamide monotherapy ( n = 29) or in combination with ETs ( n = 70) was generally well tolerated. Enzalutamide PK in women was similar to prior data on PK in men with prostate cancer. Enzalutamide decreased plasma exposure to anastrozole by approximately 90% and exemestane by approximately 50%. Enzalutamide did not significantly affect fulvestrant PK. Exposure of exemestane 50 mg/day given with enzalutamide was similar to exemestane 25 mg/day alone. Conclusions: These results support a 160 mg/day enzalutamide dose in women with breast cancer. Enzalutamide can be given in combination with fulvestrant without dose modifications. Exemestane should be doubled from 25 mg/day to 50 mg/day when given in combination with enzalutamide; this combination is being investigated in a randomized phase II study in patients with ER + /PgR + breast cancer. Clin Cancer Res; 23(15); 4046-54. ©2017 AACR . ©2017 American Association for Cancer Research.
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Caterina Guinovart
Full Text Available The pre-erythrocytic malaria vaccine RTS,S/AS02A has shown to confer protection against clinical malaria for at least 21 months in a trial in Mozambican children. Efficacy varied between different endpoints, such as parasitaemia or clinical malaria; however the underlying mechanisms that determine efficacy and its duration remain unknown. We performed a new, exploratory analysis to explore differences in the duration of protection among participants to better understand the protection afforded by RTS,S.The study was a Phase IIb double-blind, randomized controlled trial in 2022 children aged 1 to 4 years. The trial was designed with two cohorts to estimate vaccine efficacy against two different endpoints: clinical malaria (cohort 1 and infection (cohort 2. Participants were randomly allocated to receive three doses of RTS,S/AS02A or control vaccines. We did a retrospective, unplanned sub-analysis of cohort 2 data using information collected for safety through the health facility-based passive case detection system. Vaccine efficacy against clinical malaria was estimated over the first six-month surveillance period (double-blind phase and over the following 12 months (single-blind phase, and analysis was per-protocol. Adjusted vaccine efficacy against first clinical malaria episodes in cohort 2 was of 35.4% (95% CI 4.5-56.3; p = 0.029 over the double-blind phase and of 9.0% (-30.6-36.6; p = 0.609 during the single-blind phase.Contrary to observations in cohort 1, where efficacy against clinical malaria did not wane over time, in cohort 2 the efficacy decreases with time. We hypothesize that this reduced duration of protection is a result of the early diagnosis and treatment of infections in cohort 2 participants, preventing sufficient exposure to asexual-stage antigens. On the other hand, the long-term protection against clinical disease observed in cohort 1 may be a consequence of a prolonged exposure to low-dose blood-stage asexual parasitaemia
International Nuclear Information System (INIS)
Krainick-Strobel, Ute E; Lichtenegger, Werner; Wallwiener, Diethelm; Tulusan, Augustinus H; Jänicke, Fritz; Bastert, Gunther; Kiesel, Ludwig; Wackwitz, Birgit; Paepke, Stefan
2008-01-01
In recent years, preoperative volume reduction of locally advanced breast cancers, resulting in higher rates of breast-conserving surgery (BCS), has become increasingly important also in postmenopausal women. Clinical interest has come to center on the third-generation nonsteroidal aromatase inhibitors (AIs), including letrozole, for such neoadjuvant endocrine treatment. This usually lasts 3–4 months and has been extended to up to 12 months, but optimal treatment duration has not been fully established. This study was designed as a multicenter, open-label, single-arm, exploratory phase IIb/III clinical trial of letrozole 2.5 mg, one tablet daily, for 4–8 months. The primary objective was to investigate the effect of neoadjuvant treatment duration on tumor regression and BCS eligibility to identify optimal treatment duration. Tumor regression (by clinical examination, mammography, and ultrasound), shift towards BCS eligibility, and safety assessments were the main outcome measures. Standard parametric and nonparametric descriptive statistics were performed. Letrozole treatment was received by 32 of the enrolled 33 postmenopausal women (median (range): 67.0 (56–85) years) with unilateral, initially BCS-ineligible primary breast cancer (clinical stage ≥ T2, N0, M0). Letrozole treatment duration in the modified intent-to-treat (ITT; required 4 months' letrozole treatment) analysis population (29 patients) was 4 months in 14 patients and > 4 months in 15 patients. The respective per-protocol (PP) subgroup sizes were 14 and 11. The majority of partial or complete responses were observed at 4 months, though some beneficial responses occurred during prolonged letrozole treatment. Compared with baseline, median tumor size in the ITT population was reduced by 62.5% at Month 4 and by 70.0% at final study visit (Individual End). Similarly, in the PP population, respective reductions were 64.0% and 67.0%. Whereas initially all patients were mastectomy candidates
Asai, Hiroki; Abe, Natsuko; Matsushima, Ryo; Crofts, Naoko; Oitome, Naoko F; Nakamura, Yasunori; Fujita, Naoko
2014-10-01
Starch synthase (SS) IIIa has the second highest activity of the total soluble SS activity in developing rice endosperm. Branching enzyme (BE) IIb is the major BE isozyme, and is strongly expressed in developing rice endosperm. A mutant (ss3a/be2b) was generated from wild-type japonica rice which lacks SSIIa activity. The seed weight of ss3a/be2b was 74-94% of that of the wild type, whereas the be2b seed weight was 59-73% of that of the wild type. There were significantly fewer amylopectin short chains [degree of polymerization (DP) ≤13] in ss3a/be2b compared with the wild type. In contrast, the amount of long chains (DP ≥25) connecting clusters of amylopectin in ss3a/be2b was higher than in the wild type and lower than in be2b. The apparent amylose content of ss3a/be2b was 45%, which was >1.5 times greater than that of either ss3a or be2b. Both SSIIIa and BEIIb deficiencies led to higher activity of ADP-glucose pyrophosphorylase (AGPase) and granule-bound starch synthase I (GBSSI), which partly explains the high amylose content in the ss3a/be2b endosperm. The percentage apparent amylose content of ss3a and ss3a/be2b at 10 days after flowering (DAF) was higher than that of the wild type and be2b. At 20 DAF, amylopectin biosynthesis in be2b and ss3a/be2b was not observed, whereas amylose biosynthesis in these lines was accelerated at 30 DAF. These data suggest that the high amylose content in the ss3a/be2b mutant results from higher amylose biosynthesis at two stages, up to 20 DAF and from 30 DAF to maturity. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.
SARCOPENIA: DESIGNING PHASE IIB TRIALS
CHUMLEA, WM.C.; CESARI, M.; EVANS, W.J.; FERRUCCI, L.; FIELDING, R.A.; PAHOR, M.; STUDENSKI, S.; VELLAS, B.
2012-01-01
Sarcopenia is the age-related involuntary loss of skeletal muscle mass and functionality that can lead to the development of disability, frailty and increased health care costs. The development of interventions aimed at preventing and/or treating sarcopenia is complex, requiring the adoption of assumptions and standards that are not well established scientifically or clinically. A number of investigators and clinicians (both from academia and industry) met in Rome (Italy) in 2009 to develop a consensus definition of sarcopenia. Subsequently, in Albuquerque (New Mexico, USA) in 2010, the same group met again to consider the complex issues necessary for designing Phase II clinical trials for sarcopenia. Current clinical trial data indicate that fat-free mass (FFM) parameters are responsive to physical activity/nutritional treatment modalities over short time periods, but pharmacological trials of sarcopenia have yet to show significant efficacy. In order to conduct a clinical trial within a reasonable time frame, groups that model or display accelerated aging and loss of FFM are necessary. Few studies have used acceptable designs for testing treatment effects, sample sizes or primary outcomes that could provide interpretable findings or effects across studies. Dual energy x ray absorptiometry (DXA) is the measure of choice for assessing FFM, but sufficient time is needed for changes to be detected accurately and reliably. A tool set that would allow clinical, basic and epidemiological research on sarcopenia to advance rapidly toward diagnosis and treatment phases should be those reflecting function and strength. PMID:21623466
Han, J C; Yang, X D; Zhang, T; Li, H; Li, W L; Zhang, Z Y; Yao, J H
2009-02-01
This experiment was conducted to investigate the effects of 1alpha-hydroxycholecalciferol (1alpha-OH D3) on the growth performance, tibia and plasma parameters, nutrient utilization, meat quality of the breast and thigh, and type IIb sodium phosphate cotranspoter gene expression of broilers. A total of 96 males of 1-d-old Arbor Acres broilers were randomly assigned to 8 cages of 12 birds each. Two dietary treatments were applied to 4 cages each. Diet 1 was prepared as the basal diet (nonphytate phosphorus, 0.21%), whereas diet 2 was the basal diet supplemented with 5 microg/kg of 1alpha-OH D3. Results showed that supplementation of the basal diet with 1alpha-OH D3 increased growth performance, tibia ash and strength, plasma inorganic phosphate concentration, utilization of total phosphorus and nonphytate phosphorus, lightness and yellowness of the breast and thigh meat, and intestinal type IIb sodium phosphate cotranspoter mRNA expression, whereas it decreased the shear force and water-holding capacity of the thigh meat. These data suggest that the addition of 1alpha-OH D3 might improve growth performance, tibia development, and meat quality in 1- to 21-d-old broilers by increasing the absorption and retention of phosphorus.
International Nuclear Information System (INIS)
Danielsson, Ulf H.; Guijosa, Alberto; Kruczenski, Martin
2000-01-01
We examine the T-duality relation between 1+1 NCOS and the DLCQ limit of type IIA string theory. We show that, as long as there is a compact dimension, one can meaningfully define an 'NCOS' limit of IIB/A string theory even in the absence of D-branes (and even if there is no B-field). This yields a theory of closed strings with strictly positive winding, which is T-dual to DLCQ IIA/B without any D-branes. We call this the Type IIB/A Wound String Theory. The existence of decoupled sectors can be seen directly from the energy spectrum, and mirrors that of the DLCQ theory. It becomes clear then that all of the different p+1 NCOS theories are simply different states of this single Wound IIA/B theory which contain D-branes. We study some of the properties of this theory. In particular, we show that upon toroidal compactification, Wound string theory is U-dual to various Wrapped Brane theories which contain OM theory and the ODp theories as special states. (author)
Pan, Ting; Lin, Lingshang; Wang, Juan; Liu, Qiaoquan; Wei, Cunxu
2018-01-08
Endosperm starch provides prime energy for cereal seedling growth. Cereal endosperm with repression of starch branching enzyme (SBE) has been widely studied for its high resistant starch content and health benefit. However, in barley and maize, the repression of SBE changes starch component and amylopectin structure which affects grain germination and seedling establishment. A high resistant starch rice line (TRS) has been developed through inhibiting SBEI/IIb, and its starch has very high resistance to in vitro hydrolysis and digestion. However, it is unclear whether the starch resists in situ degradation in seed and influences seedling growth after grain germination. In this study, TRS and its wild-type rice cultivar Te-qing (TQ) were used to investigate the seedling growth, starch property changes, and in situ starch degradation during seedling growth. The slow degradation of starch in TRS seed restrained the seedling growth. The starch components including amylose and amylopectin were simultaneously degraded in TQ seeds during seedling growth, but in TRS seeds, the amylose was degraded faster than amylopectin and the amylopectin long branch-chains with B-type crystallinity had high resistance to in situ degradation. TQ starch was gradually degraded from the proximal to distal region of embryo and from the outer to inner in endosperm. However, TRS endosperm contained polygonal, aggregate, elongated and hollow starch from inner to outer. The polygonal starch similar to TQ starch was completely degraded, and the other starches with long branch-chains of amylopectin and B-type crystallinity were degraded faster at the early stage of seedling growth but had high resistance to in situ degradation during TRS seedling growth. The B-type crystallinity and long branch-chains of amylopectin in TRS seed had high resistance to in situ degradation, which inhibited TRS seedling growth.
International Nuclear Information System (INIS)
Aleksandrov, A.I.; Bubnov, N.N.; Kraevskii, S.L.; Prokof'ev, A.I.; Raspertova, Z.I.; Solinov, V.F.
1986-01-01
The authors study lithium borate glasses containing groups IIB to VB metal oxides. Chemically pure reagents were used to synthesize the glasses which were subjected to gamma-rays at 77 and 300 K with doses of up to 100 kR. The EST spectra were recorded on a Varian E-12 spectrometer in the 3 cm CW frequency region with a 100 kHz magnetic field modulation. It was established that after gamma-irradiation at 77 and 300 K of the lithium borate glass system containing up to 10% of cadmium, tin, thalium, and lead oxides, additional ESR lines arise in the free electron g factor region. The authors have determined the missing ESR spectra for nonactivated lithium borate glasses by studying glasses with additions of Zn, Ge, and Sb oxides
Labinaz, Marino; Madan, Mina; O'Shea, J O'Conor; Kilaru, Rakhi; Chin, Wai; Pieper, Karen; McGuire, Darren K; Saucedo, Jorge F; Talley, J David; Lui, Henry; Kitt, Michael M; Califf, Robert M; Tcheng, James T
2002-09-15
For patients undergoing nonurgent coronary stent implantation, blockade of the glycoprotein IIb/IIIa receptor with eptifibatide reduces the incidence of ischemic complications. We evaluated the interaction of eptifibatide with diabetes in patients who underwent this procedure by analyzing the 1-year outcomes of those enrolled in the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial (466 diabetic and 1,595 nondiabetic patients). At 1 year, the composite end point of death, myocardial infarction (MI), or target vessel revascuarlization (TVR) was higher in diabetic patients (24.5% vs 18.4%; p = 0.008). At 1 year, eptifibatide had a similar effect on the composite end point of death, MI, or TVR in diabetic (hazards ratio [HR] 0.71, 95% confidence interval [CI] 0.49 to 1.04) and nondiabetic patients (HR 0.80, 95% CI 0.63 to 0.99). A similar treatment effect was also seen on death or MI in both groups. The 1-year mortality rate for diabetic patients assigned to placebo was 3.5% versus 1.3% for patients receiving eptifibatide (HR 0.37, 95% CI 0.10 to 1.41); the latter rate was similar to the mortality rate of 1.4% for nondiabetic patients in the eptifibatide group. However, eptifibatide did not have a significant effect on TVR in diabetic patients (HR 0.90, 95% CI 0.57 to 1.41). Our data suggest that treatment with eptifibatide is associated with a similar relative reduction in adverse ischemic complications in diabetic and nondiabetic patients undergoing coronary stent implantation. There is no evidence of a statistical interaction in the treatment effect of eptifibatide between patients with and without diabetes.
Energy Technology Data Exchange (ETDEWEB)
Kirova, Y.M.; Bourhaleb, Z.; Campitelli, M.; De la Rochefordiere, A. [Institut Curie, Groupe de Gynecologie, Service d' Oncologie et de Radiotherapie, 75 - Paris (France); Alran, S.; Fourchotte, V. [Institut Curie, Groupe de Gynecologie, Service de Chirurgie, 75 - Paris (France); Plancher, C. [Institut Curie, Groupe de Gynecologie, Service de Biostatistique, 75 - Paris (France); Beuzeboc, P.; Cottu, P. [Institut Curie, Groupe de Gynecologie, Service d' Oncologie Medicale, 75 - Paris (France); Petrow, P. [Institut Curie, Groupe de Gynecologie, Service de Radiologie, 75 - Paris (France); Cremoux, P. de; Sastre-Garau, X. [Institut Curie, Groupe de Pathologie, Service de Radiologie, 75 - Paris (France)
2009-07-15
Purpose: To evaluate the treatment results of patients (pts) with Figo stage IB2, IIA, IIB cervical carcinoma (C.C.) treated with preoperative radio chemotherapy, followed by extended radical hysterectomy. Patients and methods: Retrospective study of 148 women treated to the Curie Institute for operable Figo Stage IB2 to IIB, biopsy proved C.C.. Among them, 70 pts, median age 46 years, were treated using the same regimen associating primary radio cis-platinum based chemotherapy,intracavitary LDR brachytherapy, followed by extended radical hysterectomy. Kaplan-Meier estimates were used to draw survival curves. Comparisons of survival distribution were assessed by the log-rank test. Results: Complete histological local-regional response was obtained in 56% of the pts (n = 39). Residual macroscopic or microscopic disease in the cervix was observed in 28 pts (40%). All but one had in situ microscopic residual C.C.. Lateral residual disease in the parametria was also present in nine pts, all with residual C.C.. Pelvic lymph nodes were free from microscopic disease in 56 pts (80%). Eight of 55 (11%) radiological N0 patients had microscopic nodal involvement, as compared to 6/15 (40%) radiological N1 (p = 0.03). Seventeen pts (25%) had residual cervix disease but negative nodes. After median follow-up of 40 months (range, 8-141), 38/70 patients (54.1%) are still alive and free of disease, six (8.6%) alive with disease, and 11 (15.8%) patients were lost for follow-up but free of disease. Conclusion: The treatment of locally advanced C.C. needs a new multidisciplinary diagnostic and treatment approach using new therapeutic arms to improve the survival and treatment tolerance among women presenting this disease. (authors)
Directory of Open Access Journals (Sweden)
Vincent Jallu
Full Text Available The HPA-1 alloimmune system carried by the platelet integrin αIIbβ3 is the primary cause of alloimmune thrombocytopenia in Caucasians and the HPA-1b allele might be a risk factor for thrombosis. HPA-1a and -1b alleles are defined by a leucine and a proline, respectively, at position 33 in the β3 subunit. Although the structure of αIIbβ3 is available, little is known about structural effects of the L33P substitution and its consequences on immune response and integrin functions.A complete 3D model of the L33-β3 extracellular domain was built and a P33 model was obtained by in silico mutagenesis. We then performed molecular dynamics simulations. Analyses focused on the PSI, I-EGF-1, and I-EGF-2 domains and confirmed higher exposure of residue 33 in the L33 β3 form. These analyses also showed major structural flexibility of all three domains in both forms, but increased flexibility in the P33 β3 form. The L33P substitution does not alter the local structure (residues 33 to 35 of the PSI domain, but modifies the structural equilibrium of the three domains.These results provide a better understanding of HPA-1 epitopes complexity and alloimmunization prevalence of HPA-1a. P33 gain of structure flexibility in the β3 knee may explain the increased adhesion capacity of HPA-1b platelets and the associated thrombotic risk. Our study provides important new insights into the relationship between HPA-1 variants and β3 structure that suggest possible effects on the alloimmune response and platelet function.
U(1) mediation of flux supersymmetry breaking
Grimm, Thomas W.; Klemm, Albrecht
2008-10-01
We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with Script N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible D-brane sector. The required internal manifolds can be constructed by non-Kähler resolutions of singular Calabi-Yau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.
The enhancon mechanism in string theory
International Nuclear Information System (INIS)
Jarv, Laur
2002-01-01
The enhancon mechanism is a specific phenomenon in string theory which resolves a certain naked spacetime singularity arising in the supergravity description related to N = 2 supersymmetric pure gauge theory. After reviewing the problem of singularities in general relativity as well as in string theory, and discussing the prototypical enhancon example constructed by wrapping D6-branes on a K3 surface, the thesis presents three generalisations to this static spherically symmetric case pertaining to large N SU(N) gauge theory. First we will use orientifolds to show how the enhancon mechanism also works in similar situations related to SO(2N+1), USp(2N) and SO(2N) gauge theories. Second we will wrap D-brane distributions on K3 to obtain the enhancon in oblate, toroidal and prolate shapes. Third we will study a rotating enhancon configuration and consider its implications for the black hole entropy and the second law of thermodynamics. (author)
A non-supersymmetric open-string theory and S-duality
International Nuclear Information System (INIS)
Bergman, O.; Gaberdiel, M.R.
1997-01-01
A non-supersymmetric ten-dimensional open-string theory is constructed as an orbifold of type I string theory, and as an orientifold of the bosonic type B theory. It is purely bosonic, and cancellation of massless tadpoles requires the gauge group to be SO(32) x SO(32). The spectrum of the theory contains a closed-string tachyon, and open-string tachyons in the (32,32) multiplet. The D-branes of this theory are analyzed, and it is found that the massless excitations of one of the 1-branes coincide with the world-sheet degrees of freedom of the D=26 bosonic string theory compactified on the SO(32) lattice. This suggests that the two theories are related by S-duality. (orig.)
Non-perturbative transitions among intersecting-brane vacua
Angelantonj, Carlo; Dudas, Emilian; Pradisi, Gianfranco; 10.1007/JHEP07(2011)123
2011-01-01
We investigate the transmutation of D-branes into Abelian magnetic backgrounds on the world-volume of higher-dimensional branes, within the framework of global models with compact internal dimensions. The phenomenon, T-dual to brane recombination in the intersecting-brane picture, shares some similarities to inverse small-instanton transitions in non-compact spaces, though in this case the Abelian magnetic background is a consequence of the compactness of the internal manifold, and is not ascribed to a zero-size non-Abelian instanton growing to maximal size. We provide details of the transition in various supersymmetric orientifolds and non-supersymmetric tachyon-free vacua with Brane Supersymmetry Breaking, both from brane recombination and from a field theory Higgs mechanism viewpoints.
U(1) mediation of flux supersymmetry breaking
International Nuclear Information System (INIS)
Grimm, Thomas W.; Klemm, Albrecht
2008-01-01
We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible D-brane sector. The required internal manifolds can be constructed by non-Kaehler resolutions of singular Calabi-Yau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.
Noncommutative o*(N) and usp*(2N) algebras and the corresponding gauge field theories
International Nuclear Information System (INIS)
Bars, I.; Sheikh-Jabbari, M.M.; Vasiliev, M.A.
2001-03-01
The extension of the noncommutative u * (N) Lie algebra to noncommutative orthogonal and symplectic Lie algebras is studied. Using an anti-automorphism of the star-matrix algebra, we show that the u * (N) can consistently be restricted to o * (N) and usp * (N) algebras that have new mathematical structures. We give explicit fundamental matrix representations of these algebras, through which the formulation for the corresponding noncommutative gauge field theories are obtained. In addition, we present a D-brane configuration with an orientifold which realizes geometrically our algebraic construction, thus embedding the new noncommutative gauge theories in superstring theory in the presence of a constant background magnetic field. Some algebraic generalizations that may have applications in other areas of physics are also discussed. (author)
Energy Technology Data Exchange (ETDEWEB)
Yoshida, Kenji [Medical University of Vienna, Comprehensive Cancer Center, Vienna (Austria); Kobe University Graduate School of Medicine, Kobe (Japan); Jastaniyah, Noha [Medical University of Vienna, Comprehensive Cancer Center, Vienna (Austria); King Faisal Specialist Hospital and Research Center, Riyadh (Saudi Arabia); Sturdza, Alina, E-mail: alina.sturdza@akhwien.at [Medical University of Vienna, Comprehensive Cancer Center, Vienna (Austria); Lindegaard, Jacob [Aarhus University Hospital, Aarhus (Denmark); Segedin, Barbara [Institute of Oncology Ljubljana, Ljubljana (Slovenia); Mahantshetty, Umesh [Tata Memorial Hospital, Mumbai (India); Rai, Bhavana [Post Graduate Institute of Medical Education and Research, Chandigarh (India); Jürgenliemk-Schulz, Ina [University Medical Center, Utrecht (Netherlands); Haie-Meder, Christine [Institut Gustave Roussy, Paris (France); Sasaki, Ryohei [Kobe University Graduate School of Medicine, Kobe (Japan); Pötter, Richard [Medical University of Vienna, Comprehensive Cancer Center, Vienna (Austria)
2015-11-15
Purpose: To assess disease response along the parametrial space according to tumor morphology in patients with International Federation of Gynecology and Obstetrics (FIGO) stage IIB and IIIB cervical cancer at the time of image-guided adaptive brachytherapy. Methods and Materials: Patients with FIGO stage IIB and IIIB cervical cancer registered as of November 2013 in the EMBRACE study were evaluated. Tumors were stratified according to morphologic subtype on magnetic resonance imaging (expansive and infiltrative), and the characteristics of those subtypes were analyzed. Parametrial involvement at diagnosis and at brachytherapy was evaluated, and the response to chemo-radiotherapy was classified as good, moderate, or poor. The response grade was compared between the 2 groups and analyzed with regard to tumor volumes, and dosimetric parameters. Results: A total of 452 patients were evaluated, of whom 186 had expansive growth type and 266 had infiltrative morphology. Patients with infiltrative tumors had more extensive disease, as indicated by a higher rate of FIGO stage IIIB disease, as well as radiologic evidence of extension into the distal parametrial space and to the pelvic side wall on magnetic resonance imaging. Cervical necrosis was more common in the infiltrative group. Good response was more common in the expansive group (34% vs 24%; P=.02), and poor response was more common in the infiltrative group (11% and 19%; P=.02). Mean gross tumor volume at diagnosis was equal in both groups (51.7 cm{sup 3}). The high-risk clinical target volume was larger in infiltrative tumors (37.9 cm{sup 3} vs 33.3 cm{sup 3}, P=.005). The mean high-risk clinical target volume D{sub 90} was slightly higher in expansive tumors (92.7 Gy and 89.4 Gy, P<.001). Conclusion: Infiltrative tumors are more advanced at presentation and respond less favorably to chemo-radiotherapy when compared with expansive tumors that are more or less equivalent in size. The use of image
Madan, Mina; Nikhil, Janarthan; Hellkamp, Anne S; Pieper, Karen S; Labinaz, Marino; Cohen, E A; Buller, Christopher E; Cantor, Warren J; Seidelin, Peter; Ducas, John; Carere, Ronald G; Natarajan, Madhu K; O'Shea, J Conor; Tcheng, James E
2009-08-01
The Enhanced Suppression of the Platelet glycoprotein IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial compared the use of eptifibatide with placebo in 2064 coronary intervention patients. It was previously reported that Canadian patients had reduced rates of 30-day and one-year death, myocardial infarction (MI) or target vessel revascularization (TVR) compared with patients in the United States (US). To examine whether operator or institutional volume differences explain the regional variation in clinical outcome. Each site received an operator and institutional volume survey. Fifty-seven sites (62%) returned complete data on 1338 patients. In this smaller cohort, Canadian patients had reduced rates of 30-day and one-year death, MI or TVR compared with US patients (6.3% versus 10.3% and 14.9% versus 20.1%, respectively; PESPRIT study, institutional volume was associated with a modest reduction in risk of death, MI or TVR over short- and long-term follow-up periods. The Canadian and US investigators and institutions selected in ESPRIT had similar annual procedural volumes. Therefore, volume variables did not explain the differential risk of clinical events observed for patients enrolled in the two countries.
String Theory clues for the low-$\\ell$ CMB ?
Kitazawa, N.
2015-05-29
"Brane Supersymmetry Breaking" is a peculiar string-scale mechanism that can unpair Bose and Fermi excitations in orientifold models. It results from the simultaneous presence, in the vacuum, of collections of D-branes and orientifolds that are not mutually BPS, and is closely tied to the scale of string excitations. It also leaves behind, for a mixing of dilaton and internal breathing mode, an exponential potential that is just too steep for a scalar to emerge from the initial singularity while descending it. As a result, in this class of models the scalar can generically bounce off the exponential wall, and this dynamics brings along, in the power spectrum, an infrared depression typically followed by a pre-inflationary peak. We elaborate on a possible link between this type of bounce and the low-$\\ell$ end of the CMB angular power spectrum. For the first 32 multipoles, one can reach a 50 % reduction in $\\chi^{\\,2}$ with respect to the standard $\\Lambda$CDM setting.
F-theory and the landscape of intersecting D7-branes
International Nuclear Information System (INIS)
Braun, Andreas
2010-01-01
In this work, the moduli of D7-branes in type IIB orientifold compactifications and their stabilization by fluxes is studied from the perspective of F-theory. In F-theory, the moduli of the D7-branes and the moduli of the orientifold are unified in the moduli space of an elliptic Calabi-Yau manifold. This makes it possible to study flux the stabilization of D7-branes in an elegant manner. To answer phenomenological questions, one has to translate the deformations of the elliptic Calabi-Yau manifold of F-theory back to the positions and the shape of the D7-branes. We address this problem by constructing the homology cycles that are relevant for the deformations of the elliptic Calabi-Yau manifold.We show the viability of our approach for the case of elliptic two- and three-folds. Furthermore, we discuss a consistency conditions related to the intersections between D7-branes and orientifold planes which is automatically fulfilled in F-theory. Finally, we use our results to study the flux stabilization of D7-branes on the orientifold K3 x T 2 /Z 2 using F-theory on K3 x K3. In this context, we derive conditions on the fluxes to stabilize a given configuration of D7-branes. (orig.)
F-theory and the landscape of intersecting D7-branes
Energy Technology Data Exchange (ETDEWEB)
Braun, Andreas
2010-02-05
In this work, the moduli of D7-branes in type IIB orientifold compactifications and their stabilization by fluxes is studied from the perspective of F-theory. In F-theory, the moduli of the D7-branes and the moduli of the orientifold are unified in the moduli space of an elliptic Calabi-Yau manifold. This makes it possible to study flux the stabilization of D7-branes in an elegant manner. To answer phenomenological questions, one has to translate the deformations of the elliptic Calabi-Yau manifold of F-theory back to the positions and the shape of the D7-branes. We address this problem by constructing the homology cycles that are relevant for the deformations of the elliptic Calabi-Yau manifold.We show the viability of our approach for the case of elliptic two- and three-folds. Furthermore, we discuss a consistency conditions related to the intersections between D7-branes and orientifold planes which is automatically fulfilled in F-theory. Finally, we use our results to study the flux stabilization of D7-branes on the orientifold K3 x T{sup 2}/Z{sub 2} using F-theory on K3 x K3. In this context, we derive conditions on the fluxes to stabilize a given configuration of D7-branes. (orig.)
Wang, Ani; Fan, Ruiqing; Dong, Yuwei; Chen, Wei; Song, Yang; Wang, Ping; Hao, Sue; Liu, Zhigang; Yang, Yulin
2016-12-20
Judicious structural design employing 2-quinolinecarboxaldehyde and 4-methylaniline was used to generate the Schiff base ligand (E)-4-methyl-N-((quinolin-2-yl)ethylidene)aniline (L). Five IIB complexes, namely, [ZnLCl 2 ] (1), [ZnL(NO 3 ) 2 ] (2), [ZnL(OAc) 2 ] 3 (3), [CdL(OAc) 2 ] 3 (4), and [HgLCl 2 ] (5) have been synthesized based on L. Single-crystal X-ray diffraction analysis indicates that complexes 1, 3 and 4 exhibit 3D networks, whereas 2 and 5 form 2D layers and 1D chains, respectively. TD-DFT calculations show a good correlation with the UV-vis absorption assigned to π → π* intraligand transitions. Furthermore, complexes 1-5 displayed strong greenish luminescent emissions (518-524 nm) in the aggregate state but weak emissions in solution (aggregation-induced emission enhancement), which may be due to the existence of C-HCl/O hydrogen bonding and ππ stacking interactions, resulting in restriction of intramolecular rotation (RIR). Variable-concentration 1 H NMR studies suggested that the aggregates undergo intramolecular changes in conformation due to intermolecular interactions. Moreover, the emission intensity and lifetime exhibited obvious increases induced by mechanical grinding and temperature reduction, which were also attributed to AIEE properties. Subsequently, complex 1 was incorporated into poly(methyl methacrylate) (PMMA), whereby 1-PMMA exhibited enhanced emission intensity (20-fold increase in comparison with that of 1), which offers opportunities for use in plastic greenhouses to increase leaf photosynthesis.
International Nuclear Information System (INIS)
Anon.
1985-01-01
Volume II-B of the hearing record contains Appendix 3 and Appendix 4 of Volume II-A. Appendix 3 provides supporting materials on the accomplishments and project summaries of the various departments under the Office of Basic Energy Sciences. This includes DOE supported work in engineering, chemistry, biology, mathematics, geology, and the energy sciences. Appendix 4 provides summaries of DOE supported work on high energy physics, which investigates the nature of matter and the behavior of matter and energy. Over 90% of the funding for this work comes from DOE, which is responsible for national planning in the effort to develop accelerator facilities, the superconducting super collider, and other physics programs
Zhou, Zhi-Wei; Chen, Xiao; Liang, Jun; Yu, Xi-Yong; Wen, Jing-Yuan; Zhou, Shu-Feng
2007-08-01
Tanshinone IIB (TSB) is a major constituent of Salvia miltiorrhiza, which is widely used in treatment of cardiovascular and central nervous system (CNS) diseases such as coronary heart disease and stroke. This study aimed to investigate the role of various drug transporters in the brain penetration of TSB using several in vitro and in vivo mouse and rat models. The uptake and efflux of TSB in rat primary microvascular endothelial cells (RBMVECs) were ATP-dependent and significantly altered in the presence of a P-glycoprotein (P-gp) or multidrug resistance associated protein (Mrp1/2) inhibitor. A polarized transport of TSB was found in RBMVEC monolayers with facilitated efflux from the abluminal to luminal side. Addition of a P-gp inhibitor (e.g. verapamil) in both abluminal and luminal sides attenuated the polarized transport. In an in situ rat brain perfusion model, TSB crossed the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier at a greater rate than that for sucrose, and the brain penetration was increased in the presence of a P-gp or Mrp1/2 inhibitor. The brain levels of TSB were only about 30% of that in the plasma and it could be increased to up to 72% of plasma levels when verapamil, quinidine, or probenecid was co-administered in rats. The entry of TSB to CNS increased by 67-97% in rats subjected to middle cerebral artery occlusion or treatment with the neurotoxin, quinolinic acid, compared to normal rats. Furthermore, The brain levels of TSB in mdr1a(-/-) and mrp1(-/-) mice were 28- to 2.6-fold higher than those in the wild-type mice. TSB has limited brain penetration through the BBB due to the contribution of P-gp and to a lesser extent of Mrp1 in rodents. Further studies are needed to confirm whether these corresponding transporters in humans are involved in limiting the penetration of TSB across the BBB and the clinical relevance.
Chen, Pei; Tang, Qin; Wang, Chunfang
2016-02-01
A sodium-dependent phosphate cotransporter gene, NaPi-IIb (slc34a2), was isolated from yellow catfish (Pelteobagrus fulvidraco) intestine through homology cloning and the rapid amplification of cDNA ends. The full-length cDNA of slc34a2 consisted of 2326 bp with an open reading frame encoding 621 amino acids, a 160-bp 5' untranslated region, and a 300-bp 3' untranslated region. The deduced amino acid sequence showed 79.0 and 70.9% sequence identity to Astyanax mexicanus and Pundamilia nyererei, respectively. The membrane-spanning domains based on the hydrophilic and hydrophobic properties of the deduced amino acids were predicted, and results showed that the putative protein had eight transmembrane domains, with the intracellular NH2 and COOH termini. Two functional regions including first intracellular loop and third extracellular loop as well as the six N-glycosylation sites in second extracellular loop were found. The slc34a2 mRNA in the tested tissues was examined through semiquantitative reverse transcription polymerase chain reaction and quantitative real-time PCR, with the highest level found in the anterior intestine, followed by the posterior and middle intestines. The slc34a2 mRNA expression in the whole intestine under different dietary phosphorus (P) treatments was detected using qPCR. The results showed that the slc34a2 expression levels in the low-P groups (0.33 and 0.56%) were significantly higher (p < 0.05) than levels in the sufficient-P (0.81%) and high-P (1.15, 1.31, and 1.57%) groups. High expression of slc34a2 mRNA in low-P groups stimulated P utilization efficiency, indicating the close relationship between genotype and phenotype in yellow catfish. In contrast with conventional strategies (formula and feeding strategies), this study provided another possible approach by using molecular techniques to increase the P utilization in yellow catfish.
Directory of Open Access Journals (Sweden)
Pedro Aide
2010-11-01
Full Text Available The RTS,S/AS02(D vaccine has been shown to have a promising safety profile, to be immunogenic and to confer protection against malaria in children and infants.We did a randomized, controlled, phase I/IIb trial of RTS,S/AS02(D given at 10, 14 and 18 weeks of age staggered with routine immunization vaccines in 214 Mozambican infants. The study was double-blind until the young child completed 6 months of follow-up over which period vaccine efficacy against new Plasmodium falciparum infections was estimated at 65.9% (95% CI 42.6-79.8, p<0.0001. We now report safety, immunogenicity and estimated efficacy against clinical malaria up to 14 months after study start. Vaccine efficacy was assessed using Cox regression models. The frequency of serious adverse events was 32.7% in the RTS,S/AS02(D and 31.8% in the control group. The geometric mean titers of anti-circumsporozoite antibodies declined from 199.9 to 7.3 EU/mL from one to 12 months post dose three of RTS,S/AS02(D, remaining 15-fold higher than in the control group. Vaccine efficacy against clinical malaria was 33% (95% CI: -4.3-56.9, p = 0.076 over 14 months of follow-up. The hazard rate of disease per 2-fold increase in anti-CS titters was reduced by 84% (95% CI 35.1-88.2, p = 0.003.The RTS,S/AS02(D malaria vaccine administered to young infants has a good safety profile and remains efficacious over 14 months. A strong association between anti-CS antibodies and risk of clinical malaria has been described for the first time. The results also suggest a decrease of both anti-CS antibodies and vaccine efficacy over time.ClinicalTrials.gov NCT00197028.
Directory of Open Access Journals (Sweden)
Zaccheaus A Jeremiah
2010-05-01
Full Text Available Zaccheaus A Jeremiah1, Justina E Oburu2, Osaro Erhabor1, Fiekumo I Buseri1, Teddy C Adias31Haematology and Blood Transfusion Science Unit, Department of Medical Laboratory Sciences, College of Health Sciences, Niger Delta University, Wilberforce Island, Nigeria; 2Department of Haematology and Blood Transfusion, University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria; 3Rivers State University of Science and Technology, Port Harcourt, NigeriaBackground: Human platelet antibodies are often implicated in some disease conditions, such as neonatal alloimmune thrombocytopenia (NAIT, idiopathic thrombocytopenic purpura (ITP and platelet refractoriness. The frequencies of these alloantibodies have not been reported in Nigeria and West Africa.Methods: Screening for allontibodies to human platelet antigens (HPA was undertaken using the GTI PakPlus® qualitative solid phase ELISA reagent. Platelet count was done using the ICSH approved procedure using 1% ammonium oxalate reagent.Study design: A cross-section of apparently healthy adult Nigerian multiparous non-pregnant women, who were staff of a tertiary health facility in the Niger Delta, Nigeria, were screened for alloantibodies to human platelet antigens.Results: Of the one hundred (100 women screened, the prevalence of anti-glycoprotein IIb/IIIa (anti-HPA-Ia,-3a,-4a was zero percent (0%, anti-glycoprotein Ia/IIa (anti-HPA-5b accounted for 30% of results, while anti-glycoprotein Ia/IIa (anti-HPA-5a was 18%. Parity was found to exert significant influence on the development to HPA antibodies (Fisher’s Exact Test = 11.683, P < 0.05; 13.577, P < 0.01. The platelet count of the women did not appear to exert any influence on the development of the antibodies (P > 0.05.Conclusion: This study has observed a high prevalence of anti-HPA-5b in our sample population. The prevalence of alloantibodies to HPA antigens was found to associate strongly with parity. These results indicate that there is a
Type IIB Ileosigmoid knotting: a case report
African Journals Online (AJOL)
2016-06-03
Jun 3, 2016 ... peritonitis [4,6,7]; hence early diagnosis and operative ... clinical and radiological presentation of type II ileosigmoid volvulus ... Emergency laparotomy with possible resection and primary anastomosis in type I or resection and ...
Type IIB Ileosigmoid knotting: a case report
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Ajak Makor
2018-02-01
Full Text Available Ileosigmoid knotting is a rare cause of acute intestinal obstruction. It is more common in Africans and Asians than in white populations and it is more prevalent in males than in females with a ratio of 14:1. It is classified into four types (I, II, III and IV with further extra two subtypes of A and B where type A is the most common presentation. Preoperative diagnosis is a challenge to the frontline doctors in the accidents and emergency departments; especially with limited diagnostic tools. Ultrasonography may be misleading in most of the cases due to the similarity of the disease with other causes of acute abdomen, especially acute appendicitis. Clinical presentation of an unprecedented intestinal obstruction with constant upper to mid-abdominal quadrant pain associated with mild to moderate abdominal distension contrary to the severe abdominal distension in sigmoid volvulus are the hallmarks that can help the surgical team to reach an accurate and early diagnosis preoperatively to avoid the devastating ischemia and gangrene in case of delay.
Global embedding of fibre inflation models
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [Dipartimento di Fisica e Astronomia, Università di Bologna,via Irnerio 46, 40126 Bologna (Italy); INFN - Sezione di Bologna,viale Berti Pichat 6/2, 40127 Bologna (Italy); Abdus Salam ICTP,Strada Costiera 11, Trieste 34151 (Italy); Muia, Francesco [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Rd., Oxford OX1 3NP (United Kingdom); Shukla, Pramod [Abdus Salam ICTP,Strada Costiera 11, Trieste 34151 (Italy)
2016-11-30
We present concrete embeddings of fibre inflation models in globally consistent type IIB Calabi-Yau orientifolds with closed string moduli stabilisation. After performing a systematic search through the existing list of toric Calabi-Yau manifolds, we find several examples that reproduce the minimal setup to embed fibre inflation models. This involves Calabi-Yau manifolds with h{sup 1,1}=3 which are K3 fibrations over a ℙ{sup 1} base with an additional shrinkable rigid divisor. We then provide different consistent choices of the underlying brane set-up which generate a non-perturbative superpotential suitable for moduli stabilisation and string loop corrections with the correct form to drive inflation. For each Calabi-Yau orientifold setting, we also compute the effect of higher derivative contributions and study their influence on the inflationary dynamics.
A flux-scaling scenario for high-scale moduli stabilization in string theory
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Ralph Blumenhagen
2015-08-01
Full Text Available Tree-level moduli stabilization via geometric and non-geometric fluxes in type IIB orientifolds on Calabi–Yau manifolds is investigated. The focus is on stable non-supersymmetric minima, where all moduli are fixed except for some massless axions. The scenario includes the purely axionic orientifold-odd moduli. A set of vacua allowing for parametric control over the moduli vacuum expectation values and their masses is presented, featuring a specific scaling with the fluxes. Uplift mechanisms and supersymmetry breaking soft masses on MSSM-like D7-branes are discussed as well. This scenario provides a complete effective framework for realizing the idea of F-term axion monodromy inflation in string theory. It is argued that, with all masses close to the Planck and GUT scales, one is confronted with working at the threshold of controlling all mass hierarchies.
A flux-scaling scenario for high-scale moduli stabilization in string theory
Energy Technology Data Exchange (ETDEWEB)
Blumenhagen, Ralph [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Font, Anamaría [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Arnold Sommerfeld Center for Theoretical Physics, LMU, Theresienstr. 37, 80333 München (Germany); Fuchs, Michael [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Herschmann, Daniela, E-mail: herschma@mpp.mpg.de [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Plauschinn, Erik [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Sekiguchi, Yuta; Wolf, Florian [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Arnold Sommerfeld Center for Theoretical Physics, LMU, Theresienstr. 37, 80333 München (Germany)
2015-08-15
Tree-level moduli stabilization via geometric and non-geometric fluxes in type IIB orientifolds on Calabi–Yau manifolds is investigated. The focus is on stable non-supersymmetric minima, where all moduli are fixed except for some massless axions. The scenario includes the purely axionic orientifold-odd moduli. A set of vacua allowing for parametric control over the moduli vacuum expectation values and their masses is presented, featuring a specific scaling with the fluxes. Uplift mechanisms and supersymmetry breaking soft masses on MSSM-like D7-branes are discussed as well. This scenario provides a complete effective framework for realizing the idea of F-term axion monodromy inflation in string theory. It is argued that, with all masses close to the Planck and GUT scales, one is confronted with working at the threshold of controlling all mass hierarchies.
Directory of Open Access Journals (Sweden)
Mandomando Inacio
2007-03-01
Full Text Available Abstract Background Previous trials of the RTS, S malaria candidate vaccine have shown that this vaccine is safe, tolerated and immunogenic. The development plan for this vaccine aims at administering it in the first year of life through the Expanded Program on Immunization (EPI. The objective was to evaluate the safety and reactogenicity of RTS, S/AS02D (0.5 ml dose, a pediatric formulation of GlaxoSmithKline Biologicals' current malaria candidate vaccine RTS, S/AS02A (0.25 ml dose. A 0.5 ml dose of AS02D is composed of the same active ingredients in the same quantities as in a 0.25 ml dose of AS02A and has been developed to be easily introduced into routine EPI practices. Methods We performed a phase I/IIb randomized double-blind bridging study in a malaria-endemic region of Mozambique, to compare the safety and immunogenicity of both candidate vaccines with the aim of replacing RTS, S/AS02A with RTS, S/AS02D as the candidate pediatric vaccine. 200 Mozambican children aged 3 to 5 years were randomized 1:1 to receive one of the 2 vaccines according to a 0, 1, 2 month schedule. Results Both vaccines were safe and had similar reactogenicity profiles. All subjects with paired pre and post-vaccination samples showed a vaccine response with respect to anti-circumsporozoite (CS antibodies irrespective of initial anti-CS serostatus. Geometric mean titers (GMTs were 191 EU/ml (95% CI 150–242 in recipients of RTS, S/AS02D compared to 180 EU/ml (95% CI 146–221 in recipients of RTS, S/AS02A. For the anti-hepatitis B surface antigen (HBsAg, all subjects were seroprotected at day 90, and the GMTs were 23978 mIU/ml (95% CI 17896–32127 in RTS, S/AS02D recipients and 17410 mIU/ml (95% CI 13322–22752 in RTS, S/AS02A recipients. There was a decrease in anti-CS GMTs between months 3 and 14 in both groups (191 vs 22 EU/mL in RTS, S/AS02D group and 180 vs 29 EU/mL in RTS, S/AS02A group. Conclusion Our data show that the RTS, S/AS02D is safe, well tolerated
International Nuclear Information System (INIS)
Anon.
1984-01-01
Volume II-B of the DOE authorization hearings for fiscal year 1985 covers testimony on high-energy and nuclear physics programs. The volume opens with a continuation of Appendix I, which contains questions directed at Dr. Alvin Trivelpiece and his responses on research at several laboratories and four construction projects. The latter include general plant projects, the Continuous Electron Beam Accelerator Facility, the Tandem/AGS Heavy Ion Transfer Line, and the University Accelerator Upgrade at the University of Washington and Yale. Two 1983 DOE/National Science Foundation reports make up Appendix II. The volume concludes with the text of the 1985 budget request for $746,105,000 and a breakdown of line item expenditures
Relating double field theory to the scalar potential of N=2 gauged supergravity
Energy Technology Data Exchange (ETDEWEB)
Blumenhagen, Ralph [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, München, 80805 (Germany); Font, Anamaria [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, München, 80805 (Germany); Arnold Sommerfeld Center for Theoretical Physics, LMU,Theresienstr. 37, München, 80333 (Germany); Plauschinn, Erik [Arnold Sommerfeld Center for Theoretical Physics, LMU,Theresienstr. 37, München, 80333 (Germany)
2015-12-18
The double field theory action in the flux formulation is dimensionally reduced on a Calabi-Yau three-fold equipped with non-vanishing type IIB geometric and non-geometric fluxes. First, we rewrite the metric-dependent reduced DFT action in terms of quantities that can be evaluated without explicitly knowing the metric on the Calabi-Yau manifold. Second, using properties of special geometry we obtain the scalar potential of N=2 gauged supergravity. After an orientifold projection, this potential is consistent with the scalar potential arising from the flux-induced superpotential, plus an additional D-term contribution.
New grand unified models with intersecting D6-branes, neutrino masses, and flipped SU(5)
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Cvetic, Mirjam [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104-6396 (United States)]. E-mail: cvetic@cvetic.hep.upenn.edu; Langacker, Paul [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104-6396 (United States); School of Natural Sciences, Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
2007-07-30
We construct new supersymmetric SU(5) grand unified models based on Z{sub 4}xZ{sub 2} orientifolds with intersecting D6-branes. Unlike constructions based on Z{sub 2}xZ{sub 2} orientifolds, the orbifold images of the three-cycles wrapped by D6-branes correspond to new configurations and thus allow for models in which, in addition to the chiral sector in 10 and 5-bar representations of SU(5), only, there can be new sectors with (15+15-bar) and (10+10-bar) vector-pairs. We construct an example of such a globally consistent, supersymmetric model with four-families, two Standard Model Higgs pair-candidates and the gauge symmetry U(5)xU(1)xSp(4). In an N=2 sector, there are 5x(15+15-bar) and 1x(10+10-bar) vector-pairs, while another N=1 sector contains one vector-pair of 15-plets. The N=2 vector-pairs can obtain a large mass dynamically by parallel D6-brane splitting in a particular two-torus. The 15-vector-pairs provide, after symmetry breaking to the Standard Model (via parallel D-brane splitting), triplet pair candidates which can in principle play a role in generating Majorana-type masses for left-handed neutrinos, though the necessary Yukawa couplings are absent in the specific construction. This model can also be interpreted as a flipped SU(5)xU(1){sub X} grand unified model where the 10-vector-pairs can play the role of Higgs fields, though again there are phenomenological difficulties for the specific construction.
Tuning and backreaction in F-term axion monodromy inflation
Directory of Open Access Journals (Sweden)
Arthur Hebecker
2015-05-01
Full Text Available We continue the development of axion monodromy inflation, focusing in particular on the backreaction of complex structure moduli. In our setting, the shift symmetry comes from a partial large complex structure limit of the underlying type IIB orientifold or F-theory fourfold. The coefficient of the inflaton term in the superpotential has to be tuned small to avoid conflict with Kähler moduli stabilisation. To allow such a tuning, this coefficient necessarily depends on further complex structure moduli. At large values of the inflaton field, these moduli are then in danger of backreacting too strongly. To avoid this, further tunings are necessary. In weakly coupled type IIB theory at the orientifold point, implementing these tunings appears to be difficult if not impossible. However, fourfolds or models with mobile D7-branes provide enough structural freedom. We calculate the resulting inflaton potential and study the feasibility of the overall tuning given the limited freedom of the flux landscape. Our preliminary investigations suggest that, even imposing all tuning conditions, the remaining choice of flux vacua can still be large enough for such models to provide a promising path to large-field inflation in string theory.
RG cascades in hyperbolic quiver gauge theories
International Nuclear Information System (INIS)
Ahl Laamara, R.; Ait Ben Haddou, M.; Belhaj, A.; Drissi, L.B.; Saidi, E.H.
2004-01-01
In this paper, we provide a general classification of supersymmatric QFT4s into three basic sets: ordinary, affine and indefinite classes. The last class, which has not been enough explored in literature, is shown to share most of properties of ordinary and affine super-QFT4s. This includes, amongst others, its embedding in type II string on local Calabi-Yau threefolds. We give realizations of these supersymmetric QFT4s as D-brane world volume gauge theories. A special interest is devoted to hyperbolic subset for its peculiar features and for the role it plays in type IIB background with non-zero axion. We also study RG flows and duality cascades in case of hyperbolic quiver theories. Comments regarding the full indefinite sector are made
Exactly soluble dynamics of (p,q) string near macroscopic fundamental strings
International Nuclear Information System (INIS)
Bak, Dongsu; Rey, Soojong; Yee, Houng
2004-01-01
We study dynamics of type-IIB bound-state of a Dirichlet string and n fundamental strings in the background of N fundamental strings. Because of supergravity potential, the bound-state string is pulled to the background fundamental strings, whose motion is described by open string rolling radion field. The string coupling can be made controllably weak and, in the limit 1 2 st n 2 st N, the bound-state energy involved is small compared to the string scale. We thus propose rolling dynamics of open string radion in this system as an exactly solvable analog for rolling dynamics of open string tachyon in decaying D-brane. The dynamics bears a novel feature that the worldsheet electric field increases monotonically to the critical value as the bound-state string falls into the background string. Close to the background string, D string constituent inside the bound-state string decouples from fundamental string constituents. (author)
Intersection spaces, spatial homology truncation, and string theory
Banagl, Markus
2010-01-01
Intersection cohomology assigns groups which satisfy a generalized form of Poincaré duality over the rationals to a stratified singular space. The present monograph introduces a method that assigns to certain classes of stratified spaces cell complexes, called intersection spaces, whose ordinary rational homology satisfies generalized Poincaré duality. The cornerstone of the method is a process of spatial homology truncation, whose functoriality properties are analyzed in detail. The material on truncation is autonomous and may be of independent interest to homotopy theorists. The cohomology of intersection spaces is not isomorphic to intersection cohomology and possesses algebraic features such as perversity-internal cup-products and cohomology operations that are not generally available for intersection cohomology. A mirror-symmetric interpretation, as well as applications to string theory concerning massless D-branes arising in type IIB theory during a Calabi-Yau conifold transition, are discussed.
One-loop Pfaffians and large-field inflation in string theory
Energy Technology Data Exchange (ETDEWEB)
Ruehle, Fabian, E-mail: fabian.ruehle@physics.ox.ac.uk [Rudolf Peierls Centre for Theoretical Physics, Oxford University, 1 Keble Road, Oxford, OX1 3NP (United Kingdom); Wieck, Clemens, E-mail: clemens.wieck@uam.es [Departamento de Física Teórica and Instituto de Física Teórica UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)
2017-06-10
We study the consistency of large-field inflation in low-energy effective field theories of string theory. In particular, we focus on the stability of Kähler moduli in the particularly interesting case where the non-perturbative superpotential of the Kähler sector explicitly depends on the inflaton field. This situation arises generically due to one-loop corrections to the instanton action. The field dependence of the modulus potential feeds back into the inflationary dynamics, potentially impairing slow roll. We distinguish between world-sheet instantons from Euclidean D-branes, which typically yield polynomial one-loop Pfaffians, and gaugino condensates, which can yield exponential or periodic corrections. In all scenarios successful slow-roll inflation imposes bounds on the magnitude of the one-loop correction, corresponding to constraints on possible compactifications. While we put a certain emphasis on Type IIB constructions with mobile D7-branes, our results seem to apply more generally.
Super jackstraws and super waterwheels
International Nuclear Information System (INIS)
Cho, Jin-Ho
2007-01-01
We construct various new BPS states of D-branes preserving 8 supersymmetries. These include super Jackstraws (a bunch of scattered D- or (p, q)-strings preserving supersymmetries), and super waterwheels (a number of D2-branes intersecting at generic angles on parallel lines while preserving supersymmetries). Super D-Jackstraws are scattered in various dimensions but are dynamical with all their intersections following a common null direction. Meanwhile, super (p, q)-Jackstraws form a planar static configuration. We show that the SO(2) subgroup of SL(2, R), the group of classical S-duality transformations in IIB theory, can be used to generate this latter configuration of variously charged (p, q)-strings intersecting at various angles. The waterwheel configuration of D2-branes preserves 8 supersymmetries as long as the 'critical' Born-Infeld electric fields are along the common direction
Little string origin of surface defects
Energy Technology Data Exchange (ETDEWEB)
Haouzi, Nathan; Schmid, Christian [Center for Theoretical Physics, University of California, Berkeley,LeConte Hall, Berkeley (United States)
2017-05-16
We derive a large class of codimension-two defects of 4d N=4 Super Yang-Mills (SYM) theory from the (2,0) little string. The origin of the little string is type IIB theory compactified on an ADE singularity. The defects are D-branes wrapping the 2-cycles of the singularity. We use this construction to make contact with the description of SYM defects due to Gukov and Witten https://arxiv.org/abs/hep-th/0612073. Furthermore, we provide a geometric perspective on the nilpotent orbit classification of codimension-two defects, and the connection to ADE-type Toda CFT. The only data needed to specify the defects is a set of weights of the algebra obeying certain constraints, which we give explicitly. We highlight the differences between the defect classification in the little string theory and its (2,0) CFT limit.
Adding a brane to the brane-anti-brane action in BSFT
International Nuclear Information System (INIS)
Jones, Nicholas T.; Henry Tye, S.-H.; Leblond, Louis
2003-01-01
We attempt to generalize the effective action for the D-brane-anti-D-brane system obtained from boundary superstring field theory (BSFT) by adding an extra D-brane to it to obtain a co-variantized action for 2 D-branes and 1 anti-D-brane. We discuss the approximations made to obtain the effective action in closed form. Among other properties, this effective action admits solitonic solutions of co-dimension 2 (vortices) when one of the D-brane is far separated from the brane-anti-brane pair. (author)
Energy Technology Data Exchange (ETDEWEB)
Marnitz, Simone, E-mail: simone.marnitz-schulze@uk-koeln.de [Department of Radiation Oncology, University of Cologne Medical Faculty, Cologne (Germany); Martus, Peter [Institute for Clinical Epidemiology and Applied Biostatistics, Eberhard-Karls-Universität Tübingen, Tübingen (Germany); Köhler, Christhardt [Department of Advanced Operative and Oncologic Gynecology, Asklepios Clinics, Hamburg (Germany); Stromberger, Carmen [Department of Radiation Oncology, University of Cologne Medical Faculty, Cologne (Germany); Asse, Elke [Department of Radiation Oncology, University Hospital Greifswald, Greifswald (Germany); Mallmann, Peter [Department of Gynecology and Obstetrics, University Hospital Cologne, Cologne (Germany); Schmidberger, Heinz [Department of Radiation Oncology, University of Mainz, Mainz (Germany); Affonso Júnior, Renato José [Department of Radiation Oncology, Hospital de Cãncer de Barretos, Barretos (Brazil); Nunes, João Soares [Department of Clinical Oncology, Hospital de Cãncer de Barretos, Barretos (Brazil); Sehouli, Jalid [Department of Gynecology, Charité–Universitätsmedizin Berlin, Berlin (Germany); Budach, Volker [Department of Radiation Oncology, University of Cologne Medical Faculty, Cologne (Germany)
2016-02-01
Purpose: The Uterus-11 trial was designed to evaluate the role of surgical staging in patients with cervical cancer before primary chemoradiation therapy (CRT). The present report provides the toxicity data stratified by the treatment arm and technique. Methods and Materials: A total of 255 patients with carcinoma of the uterine cervix (International Federation of Gynecology and Obstetrics stage IIB-IVA) were randomized to either surgical staging followed by CRT (arm A) or clinical staging followed by CRT (arm B). Patients with para-aortic metastases underwent extended field radiation therapy (RT). Brachytherapy was mandatory. The present report presents the acute therapy-related toxicities stratified by treatment arm and radiation technique. Results: A total of 240 patients were eligible (n=121 in arm A; n=119 in arm B). Of the 240 patients, 236 (98.3%) underwent external beam RT with a median total dose of 50.4 Gy. The mean treatment duration was 53 days. Of the patients, 60% underwent intensity modulated RT (IMRT). A total of 234 patients (97.5%) underwent chemotherapy, and 231 (96.3%) underwent brachytherapy, with a median single dose of 6 Gy covering the tumor to a median nominal total dose of 28 Gy. Treatment was well tolerated, with 0% grade ≥3 genitourinary and gastrointestinal toxicity, 6% grade 3 nausea, 3% grade 3 vomiting, and <2% grade 3 diarrhea. More patients after surgical staging experienced grade 2 anemia (54.3% in arm A vs 45.3% in arm B; P=.074) and grade 2 leukocytopenia (41.4% vs 31.6%; P=.56). Of the patients who received IMRT versus a 3-dimensional technique, 65.3% versus 33.7% presented with grade 2 anemia. Grade 3 gastrointestinal and grade 2 bladder toxicity were significantly reduced with the use of IMRT. Conclusions: The incidence and severity of acute therapy-related toxicity compared favorably with those from other randomized trials. Excellent adherence to treatment and treatment quality was achieved compared with patterns of
THE TYPE IIb SUPERNOVA 2011dh FROM A SUPERGIANT PROGENITOR
International Nuclear Information System (INIS)
Bersten, Melina C.; Nomoto, Ken'ichi; Folatelli, Gastón; Maeda, Keiichi; Benvenuto, Omar G.; Ergon, Mattias; Sollerman, Jesper; Benetti, Stefano; Ochner, Paolo; Tomasella, Lina; Botticella, Maria Teresa; Fraser, Morgan; Kotak, Rubina
2012-01-01
A set of hydrodynamical models based on stellar evolutionary progenitors is used to study the nature of SN 2011dh. Our modeling suggests that a large progenitor star—with R ∼ 200 R ☉ —is needed to reproduce the early light curve (LC) of SN 2011dh. This is consistent with the suggestion that the yellow super-giant star detected at the location of the supernova (SN) in deep pre-explosion images is the progenitor star. From the main peak of the bolometric LC and expansion velocities, we constrain the mass of the ejecta to be ≈2 M ☉ , the explosion energy to be E = (6-10) × 10 50 erg, and the 56 Ni mass to be approximately 0.06 M ☉ . The progenitor star was composed of a helium core of 3-4 M ☉ and a thin hydrogen-rich envelope of ≈0.1M ☉ with a main-sequence mass estimated to be in the range of 12-15 M ☉ . Our models rule out progenitors with helium-core masses larger than 8 M ☉ , which correspond to M ZAMS ∼> 25M ☉ . This suggests that a single star evolutionary scenario for SN 2011dh is unlikely.
THE PROGENITOR OF THE TYPE IIb SN 2008ax REVISITED
Energy Technology Data Exchange (ETDEWEB)
Folatelli, Gastón; Bersten, Melina C.; Benvenuto, Omar G. [Instituto de Astrofísica de La Plata (Argentina); Kuncarayakti, Hanindyo [Millennium Institute of Astrophysics (MAS), Casilla 36-D, Santiago (Chile); Maeda, Keiichi; Nomoto, Ken’ichi, E-mail: gaston@fcaglp.unlp.edu.ar [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)
2015-10-01
Hubble Space Telescope observations of the site of the supernova (SN) SN 2008ax obtained in 2011 and 2013 reveal that the possible progenitor object detected in pre-explosion images was in fact multiple. Four point sources are resolved in the new, higher-resolution images. We identify one of the sources with the fading SN. The other three objects are consistent with single supergiant stars. We conclude that their light contaminated the previously identified progenitor candidate. After subtraction of these stars, the progenitor appears to be significantly fainter and bluer than previously measured. Post-explosion photometry at the SN location indicates that the progenitor object has disappeared. If single, the progenitor is compatible with a supergiant star of B to mid-A spectral type, while a Wolf–Rayet (W-R) star would be too luminous in the ultraviolet to account for the observations. Moreover, our hydrodynamical modeling shows that the pre-explosion mass was 4–5 M{sub ⊙} and the radius was 30–50 R{sub ⊙}, which is incompatible with a W-R progenitor. We present a possible interacting binary progenitor computed with our evolutionary models that reproduces all the observational evidence. A companion star as luminous as an O9–B0 main-sequence star may have remained after the explosion.
Some new IIB group complexes of an imidazolidine ligand ...
Indian Academy of Sciences (India)
The spectral data indicate that the ligand is coordinated to zinc(II) as a bidentate ligand in imidazolidine form but it binds to ..... confirmed by determination of the minimum inhibitory ...... Yue F, Gang L, Xiu-Mei T, Ji-De W and Wei W 2008. Chin.
Fibre Inflation: Observable Gravity Waves from IIB String Compactifications
Cicoli, M; Quevedo, Fernando
2009-01-01
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_0 (3 - 4 exp{-phi/\\sqrt{3}}). Remarkably, for a broad class of vacua all adjustable parameters enter only through the overall coefficient V_0, and in particular do not enter into the slow-roll parameters. Predictions for observables are therefore completely determined by the number of e-foldings (and so are correlated with the post-inflationary reheat temperature, T_r). If the reheat temperature is T_r = 1, 100, 10^{10} or 10^{15} GeV, then N_e = 23, 28, 46 and 58 e-foldings of inflation are required after horizon exit, corresponding to a scalar spectral index n_s = 0.924, 0.937, 0.961 and 0.968, while the ratio of tensor to scalar perturbations becomes r = 0.0264, 0.0189, 0.00797 and 0.00528, withi...
Extremely high major histocompatibility complex class IIb gene ...
Indian Academy of Sciences (India)
tial for the genetic management of the captive alligator; thus much research on this ..... protected; at the same time, we must strengthen the education about alligator ... Province, Zoology Practical Skills Training Center in Fuyang. Teachers ...
The CDF calorimeter upgrade for RunIIb
Huston, J; Kuhlmann, S; Lami, S; Miller, R; Paoletti, R; Turini, N; Ukegawa, F
2004-01-01
The physics program at the Fermilab Tevatron Collider will continue to explore the high energy elementary particle physics until the LHC commissioning. The upgrade of the CDF calorimeter opens a new window for improving the jet energy resolution, important in finding various signals such as Higgs by correcting the energy loss in the dead material and adding information in the jet algorithms using charged particles. It plays an important role in soft electron tagging of b- jets and photon identification in SUSY. The upgrade of the CDF calorimeter includes: a) the replacement of slow gas detector on the front face of the Central Calorimeter with Preshower (CPR) based on 2cm thick scintillator tiles segmented in eta and Phi and read out by WLS fibers running into a groove on the surface of each tiles. The WLS fibers are placed to clear fibers after leaving the tiles; b) the replacement of the Central Crack Chamber (CCR) with 5mm thick scintillator tiles read with the same technique: To finalize the design parame...
Sarcopenia: designing phase IIb trials: international working group on sarcopenia
Sarcopenia is the age-related involuntary loss of skeletal muscle mass and functionality that can lead to the development of disability, frailty and increased health care costs. The development of interventions aimed at preventing and/or treating sarcopenia is complex, requiring the adoption of assu...
Multiwavelength observations of the Type IIb supernova 2009mg
DEFF Research Database (Denmark)
Oates, S. R.; Bayless, A. J.; Stritzinger, M. D.
2012-01-01
-time temporal index of SN 2009mg, determined from 40 d post-explosion, is consistent with the decay rate of SN 1993J, but inconsistent with the decay of 56Co. This suggests leakage of γ-rays out of the ejecta and a stellar mass on the small side of the mass distribution. Our XRT non-detection provides an upper...
THE PROGENITOR OF THE TYPE IIb SN 2008ax REVISITED
International Nuclear Information System (INIS)
Folatelli, Gastón; Bersten, Melina C.; Benvenuto, Omar G.; Kuncarayakti, Hanindyo; Maeda, Keiichi; Nomoto, Ken’ichi
2015-01-01
Hubble Space Telescope observations of the site of the supernova (SN) SN 2008ax obtained in 2011 and 2013 reveal that the possible progenitor object detected in pre-explosion images was in fact multiple. Four point sources are resolved in the new, higher-resolution images. We identify one of the sources with the fading SN. The other three objects are consistent with single supergiant stars. We conclude that their light contaminated the previously identified progenitor candidate. After subtraction of these stars, the progenitor appears to be significantly fainter and bluer than previously measured. Post-explosion photometry at the SN location indicates that the progenitor object has disappeared. If single, the progenitor is compatible with a supergiant star of B to mid-A spectral type, while a Wolf–Rayet (W-R) star would be too luminous in the ultraviolet to account for the observations. Moreover, our hydrodynamical modeling shows that the pre-explosion mass was 4–5 M ⊙ and the radius was 30–50 R ⊙ , which is incompatible with a W-R progenitor. We present a possible interacting binary progenitor computed with our evolutionary models that reproduces all the observational evidence. A companion star as luminous as an O9–B0 main-sequence star may have remained after the explosion
Energy Technology Data Exchange (ETDEWEB)
Lombardo, Davide M. [Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy); Riccioni, Fabio [INFN - Sezione di Roma, Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy); Risoli, Stefano [Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy); INFN - Sezione di Roma, Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy)
2016-12-21
We consider the N=1 superpotential generated in type-II orientifold models by non-geometric fluxes. In particular, we focus on the family of P fluxes, that are related by T-duality transformations to the S-dual of the Q flux. We determine the general rule that transforms a given flux in this family under a single T-duality transformation. This rule allows to derive a complete expression for the superpotential for both the IIA and the IIB theory for the particular case of a T{sup 6}/[ℤ{sub 2}×ℤ{sub 2}] orientifold. We then consider how these fluxes modify the generalised Bianchi identities. In particular, we derive a fully consistent set of quadratic constraints coming from the NS-NS Bianchi identities. On the other hand, the P flux Bianchi identities induce tadpoles, and we determine a set of exotic branes that can be consistently included in order to cancel them. This is achieved by determining a universal transformation rule under T-duality satisfied by all the branes in string theory.
International Nuclear Information System (INIS)
Lombardo, Davide M.; Riccioni, Fabio; Risoli, Stefano
2016-01-01
We consider the N=1 superpotential generated in type-II orientifold models by non-geometric fluxes. In particular, we focus on the family of P fluxes, that are related by T-duality transformations to the S-dual of the Q flux. We determine the general rule that transforms a given flux in this family under a single T-duality transformation. This rule allows to derive a complete expression for the superpotential for both the IIA and the IIB theory for the particular case of a T 6 /[ℤ 2 ×ℤ 2 ] orientifold. We then consider how these fluxes modify the generalised Bianchi identities. In particular, we derive a fully consistent set of quadratic constraints coming from the NS-NS Bianchi identities. On the other hand, the P flux Bianchi identities induce tadpoles, and we determine a set of exotic branes that can be consistently included in order to cancel them. This is achieved by determining a universal transformation rule under T-duality satisfied by all the branes in string theory.
Landau degeneracy and black hole entropy
International Nuclear Information System (INIS)
Costa, M.S.; Perry, M.J.
1998-01-01
We consider the supergravity solution describing a configuration of intersecting D4-branes with non-vanishing world-volume gauge fields. The entropy of such a black hole is calculated in terms of the D-branes quantised charges. The non-extreme solution is also considered and the corresponding thermodynamical quantities are calculated in terms of a D-brane/anti-D-brane system. To perform the quantum mechanical D-brane analysis we study open strings with their ends on branes with a magnetic condensate. Applying the results to our D-brane system we manage to have a perfect agreement between the D-brane entropy counting and the corresponding semi-classical result. The Landau degeneracy of the open string states describing the excitations of the D-brane system enters in a crucial way. We also derive the near-extreme results which agree with the semi-classical calculations. (orig.)
Flux compactifications and generalized geometries
International Nuclear Information System (INIS)
Grana, Mariana
2006-01-01
Following the lectures given at CERN Winter School 2006, we present a pedagogical overview of flux compactifications and generalized geometries, concentrating on closed string fluxes in type II theories. We start by reviewing the supersymmetric flux configurations with maximally symmetric four-dimensional spaces. We then discuss the no-go theorems (and their evasion) for compactifications with fluxes. We analyse the resulting four-dimensional effective theories for Calabi-Yau and Calabi-Yau orientifold compactifications, concentrating on the flux-induced superpotentials. We discuss the generic mechanism of moduli stabilization and illustrate with two examples: the conifold in IIB and a T 6 /(Z 3 x Z 3 ) torus in IIA. We finish by studying the effective action and flux vacua for generalized geometries in the context of generalized complex geometry
Flux compactifications and generalized geometries
Energy Technology Data Exchange (ETDEWEB)
Grana, Mariana [Service de Physique Theorique, CEA/Saclay, 91191 Gif-sur-Yvette Cedex (France)
2006-11-07
Following the lectures given at CERN Winter School 2006, we present a pedagogical overview of flux compactifications and generalized geometries, concentrating on closed string fluxes in type II theories. We start by reviewing the supersymmetric flux configurations with maximally symmetric four-dimensional spaces. We then discuss the no-go theorems (and their evasion) for compactifications with fluxes. We analyse the resulting four-dimensional effective theories for Calabi-Yau and Calabi-Yau orientifold compactifications, concentrating on the flux-induced superpotentials. We discuss the generic mechanism of moduli stabilization and illustrate with two examples: the conifold in IIB and a T{sup 6} /(Z{sub 3} x Z{sub 3}) torus in IIA. We finish by studying the effective action and flux vacua for generalized geometries in the context of generalized complex geometry.
From F/M-theory to K-theory and back
International Nuclear Information System (INIS)
Garcia-Etxebarria, Inaki; Uranga, Angel M.
2006-01-01
We consider discrete K-theory tadpole cancellation conditions in type IIB orientifolds with magnetised 7-branes. Cancellation of K-theory charge constrains the choices of world-volume magnetic fluxes on the latter. We describe the F-/M-theory lift of these configurations, where 7-branes are encoded in the geometry of an elliptic fibration, and their magnetic quanta correspond to supergravity 4-form field strength fluxes. In a K3 compactification example, we show that standard quantization of 4-form fluxes as integer cohomology classes in K3 automatically implies the K-theory charge cancellation constraints on the 7-brane worldvolume magnetic fluxes in string theory (as well as new previously unnoticed discrete constraints, which we also interpret). Finally, we show that flux quantization in F-/M-theory implies that 7-brane world-volume flux quantization conditions are modified in the presence of 3-form fluxes
Reflection states in Ding-Iohara-Miki algebra and brane-web for D-type quiver
Bourgine, J.-E.; Fukuda, M.; Matsuo, Y.; Zhu, R.-D.
2017-12-01
Reflection states are introduced in the vertical and horizontal modules of the Ding-Iohara-Miki (DIM) algebra (quantum toroidal gl_1 ). Webs of DIM representations are in correspondence with ( p, q)-web diagrams of type IIB string theory, under the identification of the algebraic intertwiner of Awata, Feigin and Shiraishi with the refined topological vertex. Extending the correspondence to the vertical reflection states, it is possible to engineer the N=1 quiver gauge theory of D-type (with unitary gauge groups). In this way, the Nekrasov instanton partition function is reproduced from the evaluation of expectation values of intertwiners. This computation leads to the identification of the vertical reflection state with the orientifold plane of string theory. We also provide a translation of this construction in the Iqbal-Kozcaz-Vafa refined topological vertex formalism.
Large volume axionic Swiss cheese inflation
Misra, Aalok; Shukla, Pramod
2008-09-01
Continuing with the ideas of (Section 4 of) [A. Misra, P. Shukla, Moduli stabilization, large-volume dS minimum without anti-D3-branes, (non-)supersymmetric black hole attractors and two-parameter Swiss cheese Calabi Yau's, arXiv: 0707.0105 [hep-th], Nucl. Phys. B, in press], after inclusion of perturbative and non-perturbative α corrections to the Kähler potential and (D1- and D3-) instanton generated superpotential, we show the possibility of slow roll axionic inflation in the large volume limit of Swiss cheese Calabi Yau orientifold compactifications of type IIB string theory. We also include one- and two-loop corrections to the Kähler potential but find the same to be subdominant to the (perturbative and non-perturbative) α corrections. The NS NS axions provide a flat direction for slow roll inflation to proceed from a saddle point to the nearest dS minimum.
S-folds and 4d N=3 superconformal field theories
Energy Technology Data Exchange (ETDEWEB)
Aharony, Ofer [Department of Particle Physics and Astrophysics,Weizmann Institute of Science, Rehovot 7610001 (Israel); Tachikawa, Yuji [Department of Physics, Faculty of Science,University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Kavli Institute for the Physics and Mathematics of the Universe,University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)
2016-06-08
S-folds are generalizations of orientifolds in type IIB string theory, such that the geometric identifications are accompanied by non-trivial S-duality transformations. They were recently used by García-Etxebarria and Regalado to provide the first construction of four dimensional N=3 superconformal theories. In this note, we classify the different variants of these N=3-preserving S-folds, distinguished by an analog of discrete torsion, using both a direct analysis of the different torsion classes and the compactification of the S-folds to three dimensional M-theory backgrounds. Upon adding D3-branes, these variants lead to different classes of N=3 superconformal field theories. We also analyze the holographic duals of these theories, and in particular clarify the role of discrete gauge and global symmetries in holography.
Large volume axionic Swiss cheese inflation
International Nuclear Information System (INIS)
Misra, Aalok; Shukla, Pramod
2008-01-01
Continuing with the ideas of (Section 4 of) [A. Misra, P. Shukla, Moduli stabilization, large-volume dS minimum without anti-D3-branes, (non-)supersymmetric black hole attractors and two-parameter Swiss cheese Calabi-Yau's, (arXiv: 0707.0105 [hep-th]), Nucl. Phys. B, in press], after inclusion of perturbative and non-perturbative α ' corrections to the Kaehler potential and (D1- and D3-) instanton generated superpotential, we show the possibility of slow roll axionic inflation in the large volume limit of Swiss cheese Calabi-Yau orientifold compactifications of type IIB string theory. We also include one- and two-loop corrections to the Kaehler potential but find the same to be subdominant to the (perturbative and non-perturbative) α ' corrections. The NS-NS axions provide a flat direction for slow roll inflation to proceed from a saddle point to the nearest dS minimum
String moduli stabilization at the conifold
Energy Technology Data Exchange (ETDEWEB)
Blumenhagen, Ralph; Herschmann, Daniela; Wolf, Florian [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, 80805 München (Germany)
2016-08-18
We study moduli stabilization for type IIB orientifolds compactified on Calabi-Yau threefolds in the region close to conifold singularities in the complex structure moduli space. The form of the periods implies new phenomena like exponential mass hierarchies even in the regime of negligible warping. Integrating out the heavy conic complex structure modulus leads to an effective flux induced potential for the axio-dilaton and the remaining complex structure moduli containing exponentially suppressed terms that imitate non-perturbative effects. It is shown that this scenario can be naturally combined with the large volume scenario so that all moduli are dynamically stabilized in the dilute flux regime. As an application of this moduli stabilization scheme, a string inspired model of aligned inflation is designed that features a parametrically controlled hierarchy of mass scales.
From F/M-theory to K-theory and back
Garcia-Etxebarria, I; Garcia-Etxebarria, Inaki; Uranga, Angel M.
2006-01-01
We consider discrete K-theory tadpole cancellation conditions in type IIB orientifolds with magnetised 7-branes. Cancellation of K-theory charge constrains the choices of world-volume magnetic fluxes on the latter. We describe the F-/M-theory lift of these configurations, where 7-branes are encoded in the geometry of an elliptic fibration, and their magnetic quanta correspond to supergravity 4-form field strength fluxes. In a K3 compactification example, we show that standard quantization of 4-form fluxes as integer cohomology classes in K3 automatically implies the K-theory charge cancellation constraints on the 7-brane worldvolume magnetic fluxes in string theory (as well as new previously unnoticed discrete constraints, which we also interpret). Finally, we show that flux quantization in F-/M-theory implies that 7-brane world-volume flux quantization conditions are modified in the presence of 3-form fluxes.
Geometric transitions on non-Kaehler manifolds
International Nuclear Information System (INIS)
Knauf, A.
2007-01-01
We study geometric transitions on the supergravity level using the basic idea of an earlier paper (M. Becker et al., 2004), where a pair of non-Kaehler backgrounds was constructed, which are related by a geometric transition. Here we embed this idea into an orientifold setup. The non-Kaehler backgrounds we obtain in type IIA are non-trivially fibered due to their construction from IIB via T-duality with Neveu-Schwarz flux. We demonstrate that these non-Kaehler manifolds are not half-flat and show that a symplectic structure exists on them at least locally. We also review the construction of new non-Kaehler backgrounds in type I and heterotic theory. They are found by a series of T- and S-duality and can be argued to be related by geometric transitions as well. A local toy model is provided that fulfills the flux equations of motion in IIB and the torsional relation in heterotic theory, and that is consistent with the U-duality relating both theories. For the heterotic theory we also propose a global solution that fulfills the torsional relation because it is similar to the Maldacena-Nunez background. (Abstract Copyright [2007], Wiley Periodicals, Inc.)
Geometric transitions, flops and non-Kahler manifolds: II
International Nuclear Information System (INIS)
Becker, Melanie; Dasgupta, Keshav; Katz, Sheldon; Knauf, Anke; Tatar, Radu
2006-01-01
We continue our study of geometric transitions in type II and heterotic theories. In type IIB theory we discuss an F-theory setup which clarifies many of our earlier assumptions and allows us to study gravity duals of N=1 gauge theories with arbitrary global symmetry group G. We also point out the subtle differences between global and local metrics, and show that in many cases the global descriptions are far more complicated than discussed earlier. We determine the full global description in type I/heterotic theory. In type IIA, our analysis gives rise to a local non-Kahler metric whose global description involves a particular orientifold action with gauge fluxes localised on branes. We are also able to identify the three form fields that allow for a smooth flop in the M-theory lift. We briefly discuss the issues of generalized complex structures in type IIB theory and possible half-twisted models in the heterotic duals of our type II models. In a companion paper we will present details on the topological aspects of these models
Texas A and M Univ., College Station. Vocational Instructional Services.
Part of a series of eight student learning modules in vocational agriculture, this booklet deals with evaluation of livestock. It contains sections on carcass evaluation, the evaluation of performance and production, and the design of livestock production facilities. Each of the first two sections has a glossary, and all three conclude with a…
International Nuclear Information System (INIS)
Keski-Vakkuri, E.; Kraus, P.
1998-01-01
Polchinski and Pouliot have shown that M-momentum transfer between membranes in supergravity can be understood as a non-perturbative instanton effect in gauge theory. Here we consider a dual process: electric flux transmission between D-branes. We show that this process can be described in perturbation theory as virtual string pair creation, and is closely related to Schwinger's treatment of the pair creation of charged particles in a uniform electric field. Through the application of dualities, our perturbative calculation gives results for various non-perturbative amplitudes, including M-momentum transfer between gravitons, membranes and longitudinal fivebranes. Thus perturbation theory plus dualities are sufficient to demonstrate agreement between supergravity and gauge theory for a number of M-momentum transferring processes. A variety of other processes where branes are transmitted between branes, e.g. (p,q)-string transmission in IIB theory, can also be studied. We discuss the implications of our results for proving the eleven-dimensional Lorentz invariance of matrix theory. (orig.)
Two lectures on D-geometry and noncommutative geometry
International Nuclear Information System (INIS)
Douglas, M.R.
1999-01-01
This is a write-up of lectures given at the 1998 Spring School at the Abdus Salam ICTP. We give a conceptual introduction to D-geometry, the study of geometry as seen by D-branes in string theory, and to noncommutative geometry as it has appeared in D-brane and Matrix theory physics. (author)
Energy Technology Data Exchange (ETDEWEB)
Rapisarda, Stefano M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Rubinov, Paul M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Wilcer, Neal G. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2011-03-09
The D0 VME64 LVDS SERDES Buffer (D0 VLSB) is a VME64 [Ref. ] single wide 6U module used for testing the Analog Front-End boards system [Ref. ]. The module is a custom LVDS SERDES Buffer with 4 LVDS inputs channels and can be operated stand-alone with minimal additional hardware. The current testing needs require only a 4 channel D0 VLSB module but the design allows system expansion to multiple modules. A D0 VLSB module can receive/generate trigger signals over two Lemo© [Ref. ] connectors on the module front panel. A normal test system configuration consist of a VME 64 subrack were slot 1 is occupied by a VME subrack controller and the D0 VLSB cards will occupy one or more of the remaining slots.
The Mynydd Y Cemmaes windfarm impact study - Volume IIB. Traffic impact: final report
International Nuclear Information System (INIS)
Edwards, R.; Stevenson, R.
1995-01-01
This study, from the Energy Technology Support Unit of the Department of Trade and Industry, looks at the effect on traffic movements of the construction and operation of the Mynydd y Cemmaes windfarm in Powys. The study was conducted before, during and after the construction of the windfarm over a two year period from 1992 to 1994. A large increase in traffic was observed on the unclassified road leading to the windfarm site during its construction phase, and these levels fell during commissioning and fell again during normal operation. Public concern about the traffic impact of the windfarm was then set against the 25% increase in local traffic during the windfarms operational phase. This data will be used to make more accurate predictions of traffic movements likely to occur in future windfarm construction projects. (UK)
A review of the microscopic modeling of the 5-dim. black hole of IIB ...
Indian Academy of Sciences (India)
vide quantitative predictions in particle physics. However in case ... Let us list a few properties of classical black holes: (see e.g. the text book by Wald [1]). ..... To explain the basic point let us study the metric of the black hole with the ...... I would also like to acknowledge discussions on the topics discussed here with Daniele.
100 million years of multigene family evolution: origin and evolution of the avian MHC class IIB
Czech Academy of Sciences Publication Activity Database
Goebel, J.; Promerová, Marta; Bonadonna, F.; McCoy, K. D.; Serbielle, C.; Strandh, M.; Yannic, G.; Burri, R.; Fumagalli, L.
2017-01-01
Roč. 18, č. 460 (2017), s. 1-9 ISSN 1471-2164 R&D Projects: GA ČR GAP505/10/1871 Institutional support: RVO:68081766 Keywords : Birds * Birth -death evolution * Concerted evolution * Gene duplication * Gene conversion * Major histocompatibility complex * Recombination Subject RIV: EG - Zoology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 3.729, year: 2016
1976-05-07
are: (1) portions of the San Andrea* systaft 11n greater than 100 nm to the northwest; (2) the Agua -640 Slanc fut lying approximately __nm to the...Ratio values, both in- situ and recompacted, (CBRI Avert- * can Society for Testing and Materials, Designation D 1863),, AASHO classifications (Appendix...it is estimated that a value of 10 to 20 is reasonable for in- situ material (VA.p 19701. . CBR value of greater than 20 and on the order of 30 abhold
PCR-based isolation of multigene families: lessons from the avian MHC class IIB
Czech Academy of Sciences Publication Activity Database
Burri, R.; Promerová, Marta; Goebel, J.; Fumagalli, L.
2014-01-01
Roč. 14, č. 4 (2014), s. 778-788 ISSN 1755-098X R&D Projects: GA ČR GAP505/10/1871 Institutional support: RVO:68081766 Keywords : Birds * Major histocompatibility complex * Multigene families * PCR bias Subject RIV: EG - Zoology Impact factor: 3.712, year: 2014
A review of the microscopic modeling of the 5-dim. black hole of IIB ...
Indian Academy of Sciences (India)
Firstly the event horizon has an area and there is a area law which states that in ... [4], or as we shall argue, the other possibility is to replace the paradigm of .... of the theory undergoes a drastic enough change, so that the description of ...... Our attitude will be to consider the sigma model on Е, as a resolution of the sigma.
Principles of Public School Accounting. State Educational Records and Reports Series: Handbook II-B.
Adams, Bert K.; And Others
This handbook discusses the following primary aspects of school accounting: Definitions and principles; opening the general ledger; recording the approved budget; a sample month of transactions; the balance sheet, monthly, and annual reports; subsidiary journals; payroll procedures; cafeteria fund accounting; debt service accounting; construction…
The Type IIb Supernova 2013df and its Cool Supergiant Progenitor
VanDyk, Schuyler D.; Zeng, Weikang; Fox, Ori D.; Cenko, S. Bradley; Clubb, Kelsey I.; Filippenko, Alexei; Foley, Ryan J.; Miller, Adam A.; Smith, Nathan; Kelly, Patrick L.;
2014-01-01
We have obtained early-time photometry and spectroscopy of supernova (SN) 2013df in NGC 4414. The SN is clearly of Type II b, with notable similarities to SN 1993J. From its luminosity at secondary maximum light, it appears that less Ni-56 (is approximately less than 0.06M) was synthesized in the SN 2013df explosion than was the case for the SNe II b 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 2013dfis 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(exp 4.94+/-0.06) Solar Luminosity. This leads to an effective radius Reff = 545+/-65 Solar Radius. The star likely had an initial mass in the range of 13-17Solar Mass; 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.
On the construction of SL(2,Z) type IIB 5-branes
International Nuclear Information System (INIS)
Lu, J.X.; Roy, S.
1999-01-01
This talk reviews our recent work on the construction of SL(2,Z) multiplets of type lIB superfivebranes. We here pay particular attention to the methods employed and some salient features of the solutions. (author)
International Nuclear Information System (INIS)
Hosono, Makoto; Sone, Naoaki; Endo, Keigo; Saga, Tsuneo; Kobayashi, Hisataka; Hosono, Masako N.; Sakahara, Harumi; Yasunaga, Kojiro; Konishi, Junji
1995-01-01
To experimentally assess the kinetics of platelets in thrombocytopenia, we constructed a canine model using 111 In-oxine labeled autologous platelets and an intact antiplatelet monoclonal antibody (MAb) NNKY2-11 (IgG2a). With the infusion of radiolabeled autologous platelets into dogs, the peripheral platelet count and blood radioactivity level were examined, and the radioactivity in the liver, spleen and heart was determined with scintigraphic analysis. Thereafter, i.v. injection of 100 μg/kg of NNKY2-11 had no effect on platelet counts or the biodistribution of radiolabeled platelets. However, 200 and 300 μg/kg of MAb reduced the platelets, and the radioactivity of the liver and spleen augmented clearly after injection of MAb. Platelet radioactivity in serum, which had decreased after MAb infusion, did not recover, even when peripheral platelet counts returned to the normal levels, indicating that these new platelets might be derived from the platelet-storage pool or new thrombocytogenesis. This model of antiplatelet MAb induced thrombocytopenia seems to be useful for analyzing the kinetics of platelets in thrombocytopenia
100 million years of multigene family evolution: origin and evolution of the avian MHC class IIB
Czech Academy of Sciences Publication Activity Database
Goebel, J.; Promerová, Marta; Bonadonna, F.; McCoy, K. D.; Serbielle, C.; Strandh, M.; Yannic, G.; Burri, R.; Fumagalli, L.
2017-01-01
Roč. 18, č. 460 (2017), s. 1-9 ISSN 1471-2164 R&D Projects: GA ČR GAP505/10/1871 Institutional support: RVO:68081766 Keywords : Birds * Birth-death evolution * Concerted evolution * Gene duplication * Gene conversion * Major histocompatibility complex * Recombination Subject RIV: EG - Zoology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 3.729, year: 2016
Brooks, Frank J; Grigsby, Perry W
2013-01-01
Translational relevance Many types of cancer are located and assessed via positron emission tomography (PET) using the 18F-fluorodeoxyglucose (FDG) radiotracer of glucose uptake. There is rapidly increasing interest in exploiting the intra-tumor heterogeneity observed in these FDG-PET images as an indicator of disease outcome. If this image heterogeneity is of genuine prognostic value, then it either correlates to known prognostic factors, such as tumor stage, or it indicates some as yet unkn...
HAMLET -Matroshka IIA and IIB experiments aboard the ISS: comparison of organ doses
Kato, Zoltan; Reitz, Guenther; Berger, Thomas; Bilski, Pawel; Hajek, Michael; Sihver, Lembit; Palfalvi, Jozsef K.; Hager, Luke; Burmeister, Soenke
The Matroshka experiments and the related FP7 HAMLET project aimed to study the dose burden of the cosmic rays in the organs of the crew working inside and outside the ISS. Two of the experiments will be discussed. They were performed in two different locations inside the ISS: during the Matroshka 2A (in 2006) the phantom was stored in the Russian Docking Module (Pirs), while during the Matroshka 2B (in 2007-08) it was inside the Russian Service Module (Zvezda). Both experiments were performed in the decreasing phase of the solar cycle. Solid state nuclear track detectors (SSNTD) were applied to investigate the dose contribution of the high LET radiation above ˜10 keV/µm. Two configurations of SSNTDs stacks were constructed: one for the exposure in the so called organ dose boxes (in the lung and kidney), another one for the skin dose measurements, embedded in the nomex poncho of the Phantom. In addition a reference package was placed outside the phantom. After exposure the detectors were transferred to the Earth for data evaluation. Short and long etching procedures were applied to distinguish the high and low LET particles, respectively. The particle tracks were evaluated by a semi automated image analyzer. Addi-tionally manual track parameter measurements were performed on very long tracks. As the result of measurements the LET spectra were deduced. Based on these spectra, the absorbed dose, the dose equivalent and the mean quality factor were calculated. The configuration of the stacks, the methods of the calibration and evaluation and finally the results will be presented and compared. The multiple etching and the combined evaluation method allowed to determine the fraction of the dose originated from HZE particles (Z>2 and range > major axis). Further on, data eval-uation was performed to separate the secondary particles (target fragments) from the primary particles. Although the number of high LET particles above a ˜80 keV/µm was found to be higher during the Matroshka 2B experiment than in the previous phase it was not possible to attribute this observation to the lower Sun activity in 2008, since the locations inside the ISS were different. The HAMLET project is funded by the European Commission under the EUs Seventh Frame-work Programme (FP7) under Project Nr: 218817 and coordinated by the German Aerospace Center (DLR) http://www-fp7-hamlet.eu
Special Aviation Fire and Explosion Reduction (SAFER) Advisory Committee. Volume IIB.
1980-06-26
alternates be identified collectively as the "SAFER Advisory Committee," or simply the Committee. 2. That the Committee serve as the decision-making body...iefta 10 e - Avisttln Kal £s1a~r*W. Odke Of W- rPs A..ecn~e "I t12, AdOWt(~ 0 W ae Itirea~t pgsPer110 I’o Mhet Cuxlser Attenton. Rulem LlozkCL is ira...factors, such as bur.t.it ot inha~ation of toxic gases. It is only in recent years that t-e :37 o actempted to collect such data. 4. Except for the KC
In vitro fluorescence studies of transcription factor IIB-DNA interaction.
Górecki, Andrzej; Figiel, Małgorzata; Dziedzicka-Wasylewska, Marta
2015-01-01
General transcription factor TFIIB is one of the basal constituents of the preinitiation complex of eukaryotic RNA polymerase II, acting as a bridge between the preinitiation complex and the polymerase, and binding promoter DNA in an asymmetric manner, thereby defining the direction of the transcription. Methods of fluorescence spectroscopy together with circular dichroism spectroscopy were used to observe conformational changes in the structure of recombinant human TFIIB after binding to specific DNA sequence. To facilitate the exploration of the structural changes, several site-directed mutations have been introduced altering the fluorescence properties of the protein. Our observations showed that binding of specific DNA sequences changed the protein structure and dynamics, and TFIIB may exist in two conformational states, which can be described by a different microenvironment of W52. Fluorescence studies using both intrinsic and exogenous fluorophores showed that these changes significantly depended on the recognition sequence and concerned various regions of the protein, including those interacting with other transcription factors and RNA polymerase II. DNA binding can cause rearrangements in regions of proteins interacting with the polymerase in a manner dependent on the recognized sequences, and therefore, influence the gene expression.
Nonmuscle myosin IIB as a therapeutic target for the prevention of relapse to methamphetamine use
Young, Erica J.; Blouin, Ashley M.; Briggs, Sherri B.; Sillivan, Stephanie E.; Lin, Li; Cameron, Michael D.; Rumbaugh, Gavin; Miller, Courtney A.
2015-01-01
Memories associated with drug use increase vulnerability to relapse in substance use disorder (SUD) and there are no pharmacotherapies for the prevention of relapse. Previously, we reported a promising finding that storage of memories associated with methamphetamine (METH), but not memories for fear or food reward, is vulnerable to disruption by actin depolymerization in the basolateral amygdala complex (BLC). However, actin is not a viable therapeutic target because of its numerous functions throughout the body. Here we report the discovery of a viable therapeutic target, nonmuscle myosin II (NMIIB), a molecular motor that supports memory by directly driving synaptic actin polymerization. A single intra-BLC treatment with Blebbistatin, a small molecule inhibitor of class II myosin isoforms, including NMIIB, produced a long-lasting disruption of context-induced drug seeking (at least 30 days). Further, post-consolidation genetic knockdown of Myh10, the heavy chain of the most highly expressed NMII in the BLC, was sufficient to produce METH-associated memory loss. Blebbistatin was found to be highly brain penetrant. A single systemic injection of the compound selectively disrupted the storage of METH-associated memory and reversed the accompanying increase in BLC spine density. This effect was specific to METH-associated memory, as it had no effect on an auditory fear memory. The effect was also independent of retrieval, as METH-associated memory was disrupted twenty-four hours after a single systemic injection of Blebbistatin delivered in the home cage. Together, these results argue for the further development of small molecule inhibitors of nonmuscle myosin II as potential therapeutics for the prevention of SUD relapse triggered by drug associations. PMID:26239291
MADJID, MAHATIR
2014-01-01
2014 MAHATIR MADJID (B111 10 374), Pelaksanaan Pemberian Hak Narapidana Mendapatkan Pembebasan Bersayarat (Studi Kasus Rutana Kelas II B Masamba), dibimbing oleh Prof. Dr. Muhadar, S.H.,M.S. selaku pembimbing l dan Haeranah, S.H., M.H. selaku pembimbing ll. Penelitian ini bertujuan untuk mengetahui bagaimana pelaksanaan pemberian hak narapidana mendapatkan pembebasan bersayarat di Rutan kelas II B Masamba. Penelitian ini ...
String theory for heavy-ion physicists
International Nuclear Information System (INIS)
Natsuume, Makoto
2007-01-01
In this article, we review the AdS/CFT duality for non-experts. Superstring theory has objects so-called D-branes, which are the key to understand the AdS/CFT duality. What is important about the D-brane is that the D-brane has two different descriptions. As I will explain in detail below, the D-brane can be described either by a gauge theory or by a black hole. So, the D-brane connects these two entirely different systems. However, the simplest AdS/CFT duality involves only adjoint matter and there is no fundamental matter such as quarks. Thus, an important question to address if we want to use the AdS/CFT duality for more realistic scenarios is how one can include fundamental matter. I will explain a simple way to describe fundamental matter; Sugimoto discusses more realistic methods in his article (in this volume). (author)
A realistic intersecting D6-brane model after the first LHC run
Li, Tianjun; Nanopoulos, D. V.; Raza, Shabbar; Wang, Xiao-Chuan
2014-08-01
needed to probe our D-brane model.
Geometry and physics of branes
Energy Technology Data Exchange (ETDEWEB)
Gal' tsov, D V
2003-03-21
The book brings together the contents of lecture courses delivered at the school 'Geometry and Physics of Branes' which took place at the Center 'Alessandro Volta' (Como, Italy) in the spring of 2001. The purpose of the school was to provide an introduction to some lines of research, related to the notion of branes in superstring theory, which are in the focus of attention both in the physical and mathematical communities. The book is structured into three parts: the first contains an elementary introduction to branes, the second is devoted to physical aspects (conformal field theory on open and unoriented surfaces and topics in string tachyon dynamics), and the last contains some more formal mathematical developments. An introduction to branes is given in a remarkably lucid contribution by A Lerda. It opens with a construction of p-brane solutions in classical IIA and IIB supergravities with particular emphasis on the 'fundamental string' solution, the NS5-brane and the D3-brane. Then, the quantum description of D-branes is discussed in terms of boundary states of the closed superstring, which is an alternative to the more common description in terms of open strings with Dirichlet boundary conditions in the transverse to the brane directions. When a constant gauge field is present in the D-brane worldvolume, the boundary states are coherent states of the string oscillators depending on the field strength tensor. The couplings of the brane to the bulk fields - the graviton, the dilaton, and the Kalb-Ramond fields - are then extracted and shown to be precisely the ones that are produced by the Dirac-Born-Infeld action governing the low-energy dynamics of the D-brane derived using the open strings formalism. It is also shown that in the classical limit, the boundary states correctly reproduce the parameters of the corresponding classical solutions. The second part of the book starts with a contribution by Y S Stanev devoted to the two
Geometry and physics of branes
International Nuclear Information System (INIS)
Gal'tsov, D V
2003-01-01
The book brings together the contents of lecture courses delivered at the school 'Geometry and Physics of Branes' which took place at the Center 'Alessandro Volta' (Como, Italy) in the spring of 2001. The purpose of the school was to provide an introduction to some lines of research, related to the notion of branes in superstring theory, which are in the focus of attention both in the physical and mathematical communities. The book is structured into three parts: the first contains an elementary introduction to branes, the second is devoted to physical aspects (conformal field theory on open and unoriented surfaces and topics in string tachyon dynamics), and the last contains some more formal mathematical developments. An introduction to branes is given in a remarkably lucid contribution by A Lerda. It opens with a construction of p-brane solutions in classical IIA and IIB supergravities with particular emphasis on the 'fundamental string' solution, the NS5-brane and the D3-brane. Then, the quantum description of D-branes is discussed in terms of boundary states of the closed superstring, which is an alternative to the more common description in terms of open strings with Dirichlet boundary conditions in the transverse to the brane directions. When a constant gauge field is present in the D-brane worldvolume, the boundary states are coherent states of the string oscillators depending on the field strength tensor. The couplings of the brane to the bulk fields - the graviton, the dilaton, and the Kalb-Ramond fields - are then extracted and shown to be precisely the ones that are produced by the Dirac-Born-Infeld action governing the low-energy dynamics of the D-brane derived using the open strings formalism. It is also shown that in the classical limit, the boundary states correctly reproduce the parameters of the corresponding classical solutions. The second part of the book starts with a contribution by Y S Stanev devoted to the two-dimensional conformal field
Holomorphic couplings in non-perturbative string compactifications
Energy Technology Data Exchange (ETDEWEB)
Klevers, Denis Marco
2011-06-15
In this thesis we present an analysis of several aspects of four-dimensional, non-perturbative N = 1 compactifications of string theory. Our focus is on the study of brane dynamics and their effective physics as encoded in the holomorphic couplings of the low-energy N=1 effective action, most prominently the superpotential W. The thesis is divided into three parts. In part one we derive the effective action of a spacetime-filling D5-brane in generic Type IIB Calabi-Yau orientifold compactifications. In the second part we invoke tools from string dualities, namely from F-theory, heterotic/F-theory duality and mirror symmetry, for a more elaborate study of the dynamics of (p, q) 7-branes and heterotic five-branes. In this context we demonstrate exact computations of the complete perturbative effective superpotential, both due to branes and background fluxes. Finally, in the third part we present a novel geometric description of five-branes in Type IIB and heterotic M-theory Calabi-Yau compactifications via a non-Calabi-Yau threefold Z{sub 3}, that is canonically constructed from the original five-brane and Calabi-Yau threefold Z{sub 3} via a blow-up. We exploit the use of the blow-up threefold Z{sub 3} as a tool to derive open-closed Picard-Fuchs differential equations, that govern the complete effective brane and flux superpotential. In addition, we present first evidence to interpret Z{sub 3} as a flux compactification dual to the original five-brane by defining an SU(3)-structure on Z{sub 3}, that is generated dynamically by the five-brane backreaction. (orig.)
Holomorphic couplings in non-perturbative string compactifications
International Nuclear Information System (INIS)
Klevers, Denis Marco
2011-06-01
In this thesis we present an analysis of several aspects of four-dimensional, non-perturbative N = 1 compactifications of string theory. Our focus is on the study of brane dynamics and their effective physics as encoded in the holomorphic couplings of the low-energy N=1 effective action, most prominently the superpotential W. The thesis is divided into three parts. In part one we derive the effective action of a spacetime-filling D5-brane in generic Type IIB Calabi-Yau orientifold compactifications. In the second part we invoke tools from string dualities, namely from F-theory, heterotic/F-theory duality and mirror symmetry, for a more elaborate study of the dynamics of (p, q) 7-branes and heterotic five-branes. In this context we demonstrate exact computations of the complete perturbative effective superpotential, both due to branes and background fluxes. Finally, in the third part we present a novel geometric description of five-branes in Type IIB and heterotic M-theory Calabi-Yau compactifications via a non-Calabi-Yau threefold Z 3 , that is canonically constructed from the original five-brane and Calabi-Yau threefold Z 3 via a blow-up. We exploit the use of the blow-up threefold Z 3 as a tool to derive open-closed Picard-Fuchs differential equations, that govern the complete effective brane and flux superpotential. In addition, we present first evidence to interpret Z 3 as a flux compactification dual to the original five-brane by defining an SU(3)-structure on Z 3 , that is generated dynamically by the five-brane backreaction. (orig.)
D1/D5 systems in N=4 string theories
International Nuclear Information System (INIS)
Gava, Edi; Hammou, Amine B.; Morales, Jose F.; Narain, Kumar S.
2001-01-01
We propose CFT descriptions of the D1/D5 system in a class of freely acting Z 2 orbifolds/orientifolds of type IIB theory, with sixteen unbroken supercharges. The CFTs describing D1/D5 systems involve N=(4,4) or N=(4,0) sigma models on (R 3 xS 1 xT 4 x(T 4 ) N /S N )/Z 2 , where the action of Z 2 is diagonal and its precise nature depends on the model. We also discuss D1(D5)-brane states carrying non-trivial Kaluza-Klein charges, which correspond to excitations of two-dimensional CFTs of the type (R 3 xS 1 xT 4 ) N /S N xZ 2 N . The resulting multiplicities for two-charge bound states are shown to agree with the predictions of U-duality. We raise a puzzle concerning the multiplicities of three-charge systems, which is generically present in all vacuum configurations with sixteen unbroken supercharges studied so far, including the more familiar type IIB on K3 case: the constraints put on BPS counting formulae by U-duality are apparently in contradiction with any CFT interpretation. We argue that the presence of RR backgrounds appearing in the symmetric product CFT may provide a resolution of this puzzle. Finally, we show that the whole tower of D-instanton corrections to certain 'BPS saturated couplings' in the low energy effective actions match with the corresponding one-loop threshold corrections on the dual fundamental string side
On 'light' fermions and proton stability in 'big divisor' D3/D7 large volume compactifications
International Nuclear Information System (INIS)
Misra, Aalok; Shukla, Pramod
2011-01-01
Building on our earlier work (Misra and Shukla, Nucl. Phys. B 827:112, 2010; Phys. Lett. B 685:347-352, 2010), we show the possibility of generating ''light'' fermion mass scales of MeV-GeV range (possibly related to the first two generations of quarks/leptons) as well as eV (possibly related to first two generations of neutrinos) in type IIB string theory compactified on Swiss-Cheese orientifolds in the presence of a mobile space-time filling D3-brane restricted to (in principle) stacks of fluxed D7-branes wrapping the ''big'' divisor Σ B . This part of the paper is an expanded version of the latter half of Sect. 3 of a published short invited review (Misra, Mod. Phys. Lett. A 26:1, 2011) written by one of the authors [AM ]. Further, we also show that there are no SUSY GUT-type dimension-five operators corresponding to proton decay, and we estimate the proton lifetime from a SUSY GUT-type four-fermion dimension-six operator to be 10 61 years. Based on GLSM calculations in (Misra and Shukla, Nucl. Phys. B 827:112, 2010) for obtaining the geometric Kaehler potential for the ''big divisor,'' using further the Donaldson's algorithm, we also briefly discuss in the first of the two appendices the metric for the Swiss-Cheese Calabi-Yau used, which we obtain and which becomes Ricci flat in the large-volume limit. (orig.)
On `light' fermions and proton stability in `big divisor' D3/ D7 large volume compactifications
Misra, Aalok; Shukla, Pramod
2011-06-01
Building on our earlier work (Misra and Shukla, Nucl. Phys. B 827:112, 2010; Phys. Lett. B 685:347-352, 2010), we show the possibility of generating "light" fermion mass scales of MeV-GeV range (possibly related to the first two generations of quarks/leptons) as well as eV (possibly related to first two generations of neutrinos) in type IIB string theory compactified on Swiss-Cheese orientifolds in the presence of a mobile space-time filling D3-brane restricted to (in principle) stacks of fluxed D7-branes wrapping the "big" divisor Σ B . This part of the paper is an expanded version of the latter half of Sect. 3 of a published short invited review (Misra, Mod. Phys. Lett. A 26:1, 2011) written by one of the authors [AM]. Further, we also show that there are no SUSY GUT-type dimension-five operators corresponding to proton decay, and we estimate the proton lifetime from a SUSY GUT-type four-fermion dimension-six operator to be 1061 years. Based on GLSM calculations in (Misra and Shukla, Nucl. Phys. B 827:112, 2010) for obtaining the geometric Kähler potential for the "big divisor," using further the Donaldson's algorithm, we also briefly discuss in the first of the two appendices the metric for the Swiss-Cheese Calabi-Yau used, which we obtain and which becomes Ricci flat in the large-volume limit.
Non-geometric flux vacua, S-duality and algebraic geometry
International Nuclear Information System (INIS)
Guarino, Adolfo; Weatherill, George James
2009-01-01
The four dimensional gauged supergravities descending from non-geometric string compactifications involve a wide class of flux objects which are needed to make the theory invariant under duality transformations at the effective level. Additionally, complex algebraic conditions involving these fluxes arise from Bianchi identities and tadpole cancellations in the effective theory. In this work we study a simple T and S-duality invariant gauged supergravity, that of a type IIB string compactified on a T 6 /Z 2 x Z 2 orientifold with O3/O7-planes. We build upon the results of recent works and develop a systematic method for solving all the flux constraints based on the algebra structure underlying the fluxes. Starting with the T-duality invariant supergravity, we find that the fluxes needed to restore S-duality can be simply implemented as linear deformations of the gauge subalgebra by an element of its second cohomology class. Algebraic geometry techniques are extensively used to solve these constraints and supersymmetric vacua, centering our attention on Minkowski solutions, become systematically computable and are also provided to clarify the methods.
On tadpoles and vacuum redefinitions in String Theory
International Nuclear Information System (INIS)
Dudas, E.; Nicolosi, M.; Pradisi, G.; Sagnotti, A.
2005-01-01
Tadpoles accompany, in one form or another, all attempts to realize supersymmetry breaking in String Theory, making the present constructions at best incomplete. Whereas these tadpoles are typically large, a closer look at the problem from a perturbative viewpoint has the potential of illuminating at least some of its qualitative features in String Theory. A possible scheme to this effect was proposed long ago by Fischler and Susskind, but incorporating background redefinitions in string amplitudes in a systematic fashion has long proved very difficult. In the first part of this paper, drawing from field theory examples, we thus begin to explore what one can learn by working perturbatively in a 'wrong' vacuum. While unnatural in Field Theory, this procedure presents evident advantages in String Theory, whose definition in curved backgrounds is mostly beyond reach at the present time. At the field theory level, we also identify and characterize some special choices of vacua where tadpole resummations terminate after a few contributions. In the second part we present a notable example where vacuum redefinitions can be dealt with to some extent at the full string level, providing some evidence for a new link between IIB and 0B orientifolds. We finally show that NS-NS tadpoles do not manifest themselves to lowest order in certain classes of string constructions with broken supersymmetry and parallel branes, including brane-antibrane pairs and brane supersymmetry breaking models, that therefore have UV-finite threshold corrections at one loop
International Nuclear Information System (INIS)
Hebecker, A.; March-Russell, J.
2007-01-01
We attempt to quantify the widely-held belief that large hierarchies induced by strongly-warped geometries are common in the string theory landscape. To this end, we focus on the arguably best-understood subset of vacua-type IIB Calabi-Yau orientifolds with non-perturbative Kaehler stabilization and a SUSY-breaking uplift (the KKLT setup). Within this framework, vacua with a realistically small cosmological constant are expected to come from Calabi-Yaus with a large number of 3-cycles. For appropriate choices of flux numbers, many of these 3-cycles can, in general, shrink to produce near-conifold geometries. Thus, a simple statistical analysis in the spirit of Denef and Douglas allows us to estimate the expected number and length of Klebanov-Strassler throats in the given set of vacua. We find that throats capable of explaining the electroweak hierarchy are expected to be present in a large fraction of the landscape vacua while shorter throats are essentially unavoidable in a statistical sense
Supergravity and supersymmetry breaking in four and five dimensions
International Nuclear Information System (INIS)
Ellis, John; Lalak, Zygmunt; Pokorski, Stefan; Thomas, Steven
1999-01-01
We discuss supersymmetry breaking in the field-theoretical limit of the strongly coupled heterotic string compactified on a Calabi-Yau manifold, from the different perspectives of four and five dimensions. The former applies to light degrees of freedom below the threshold for five-dimensional Kaluza-Klein excitations, whereas the five-dimensional perspective is also valid up to the Calabi-Yau scale. We show how, in the latter case, two gauge sectors separated in the fifth dimension are combined to form a consistent four-dimensional supergravity. In the lowest order of the κ 2/3 expansion, we show how a four-dimensional supergravity with gauge kinetic function f 1,2 =S is reproduced, and we show how higher-order terms give rise to four-dimensional operators that differ in the two gauge sectors. In the four-dimensional approach, supersymmetry is seen to be broken when condensates form on one or both walls, and the goldstino may have a non-zero dilatino component. As in the five-dimensional approach, the Lagrangian is not a perfect square, and we have not identified a vacuum with broken supersymmetry and zero vacuum energy. We derive soft supersymmetry-breaking terms for non-standard perturbative embeddings, that are relevant in more general situations such as type I/type IIB orientifold models
Higher-Derivative Supergravity and Moduli Stabilization
International Nuclear Information System (INIS)
Ciupke, David; Westphal, Alexander; Louis, Jan; Hamburg Univ.
2015-05-01
We review the ghost-free four-derivative terms for chiral superfields in N=1 supersymmetry and supergravity. These terms induce cubic polynomial equations of motion for the chiral auxiliary fields and correct the scalar potential. We discuss the different solutions and argue that only one of them is consistent with the principles of effective field theory. Special attention is paid to the corrections along flat directions which can be stabilized or destabilized by the higher-derivative terms. We then compute these higher-derivative terms explicitly for the type IIB string compactified on a Calabi-Yau orientifold with fluxes via Kaluza-Klein reducing the (α') 3 R 4 corrections in ten dimensions for the respective N=1 Kaehler moduli sector. We prove that together with flux and the known (α') 3 -corrections the higher-derivative term stabilizes all Calabi-Yau manifolds with positive Euler number, provided the sign of the new correction is negative.
Toric K3-fibred Calabi-Yau manifolds with del Pezzo divisors for string compactifications
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Mayrhofer, Christoph [Heidelberg Univ. (Germany). Inst. fuer Theoretische Physik; Kreuzer, Maximilian
2011-06-15
We analyse several explicit toric examples of compact K3-fibred Calabi-Yau three-folds which can be used for the study of string dualities and are crucial ingredients for the construction of LARGE Volume type IIB vacua with promising applications to cosmology and particle phenomenology. In order to build a phenomenologically viable model, on top of the two moduli corresponding to the base and the K3 fibre, we demand also the existence of two additional rigid divisors: the first supporting the non-perturbative effects needed to achieve moduli stabilisation, and the second allowing the presence of chiral matter on wrapped D-branes. We clarify the topology of these rigid divisors by discussing the interplay between a diagonal structure of the Calabi-Yau volume and D-terms. Del Pezzo divisors appearing in the volume form in a completely diagonal way are natural candidates for supporting non-perturbative effects and for quiver constructions, while 'non-diagonal' del Pezzo and rigid but not del Pezzo divisors are particularly interesting for model building in the geometric regime. Searching through the existing list of four dimensional reflexive lattice polytopes, we find 158 examples admitting a Calabi-Yau hypersurface which is a K3 fibration with four Kaehler moduli where at least one of them is a 'diagonal' del Pezzo. We work out explicitly the topological details of a few examples showing how, in the case of simplicial polytopes, all the del Pezzo divisors are 'diagonal', while 'non-diagonal' ones appear only in the case of non-simplicial polytopes. A companion paper will use these results in the study of moduli stabilisation for globally consistent explicit Calabi-Yau compactifications with the local presence of chirality. (orig.)
Toric K3-fibred Calabi-Yau manifolds with del Pezzo divisors for string compactifications
International Nuclear Information System (INIS)
Cicoli, Michele; Mayrhofer, Christoph; Kreuzer, Maximilian
2011-06-01
We analyse several explicit toric examples of compact K3-fibred Calabi-Yau three-folds which can be used for the study of string dualities and are crucial ingredients for the construction of LARGE Volume type IIB vacua with promising applications to cosmology and particle phenomenology. In order to build a phenomenologically viable model, on top of the two moduli corresponding to the base and the K3 fibre, we demand also the existence of two additional rigid divisors: the first supporting the non-perturbative effects needed to achieve moduli stabilisation, and the second allowing the presence of chiral matter on wrapped D-branes. We clarify the topology of these rigid divisors by discussing the interplay between a diagonal structure of the Calabi-Yau volume and D-terms. Del Pezzo divisors appearing in the volume form in a completely diagonal way are natural candidates for supporting non-perturbative effects and for quiver constructions, while 'non-diagonal' del Pezzo and rigid but not del Pezzo divisors are particularly interesting for model building in the geometric regime. Searching through the existing list of four dimensional reflexive lattice polytopes, we find 158 examples admitting a Calabi-Yau hypersurface which is a K3 fibration with four Kaehler moduli where at least one of them is a 'diagonal' del Pezzo. We work out explicitly the topological details of a few examples showing how, in the case of simplicial polytopes, all the del Pezzo divisors are 'diagonal', while 'non-diagonal' ones appear only in the case of non-simplicial polytopes. A companion paper will use these results in the study of moduli stabilisation for globally consistent explicit Calabi-Yau compactifications with the local presence of chirality. (orig.)
Supersymmetric gauge theories from string theory
International Nuclear Information System (INIS)
Metzger, St.
2005-12-01
This thesis presents various ways to construct four-dimensional quantum field theories from string theory. In a first part we study the generation of a supersymmetric Yang-Mills theory, coupled to an adjoint chiral superfield, from type IIB string theory on non-compact Calabi-Yau manifolds, with D-branes wrapping certain sub-cycles. Properties of the gauge theory are then mapped to the geometric structure of the Calabi-Yau space. Even if the Calabi-Yau geometry is too complicated to evaluate the geometric integrals explicitly, one can then always use matrix model perturbation theory to calculate the effective superpotential. The second part of this work covers the generation of four-dimensional super-symmetric gauge theories, carrying several important characteristic features of the standard model, from compactifications of eleven-dimensional supergravity on G 2 -manifolds. If the latter contain conical singularities, chiral fermions are present in the four-dimensional gauge theory, which potentially lead to anomalies. We show that, locally at each singularity, these anomalies are cancelled by the non-invariance of the classical action through a mechanism called 'anomaly inflow'. Unfortunately, no explicit metric of a compact G 2 -manifold is known. Here we construct families of metrics on compact weak G 2 -manifolds, which contain two conical singularities. Weak G 2 -manifolds have properties that are similar to the ones of proper G 2 -manifolds, and hence the explicit examples might be useful to better understand the generic situation. Finally, we reconsider the relation between eleven-dimensional supergravity and the E 8 x E 8 -heterotic string. This is done by carefully studying the anomalies that appear if the supergravity theory is formulated on a ten-manifold times the interval. Again we find that the anomalies cancel locally at the boundaries of the interval through anomaly inflow, provided one suitably modifies the classical action. (author)
On the Generalized Geometry Origin of Noncommutative Gauge Theory
Jurco, Branislav; Vysoky, Jan
2013-01-01
We discuss noncommutative gauge theory from the generalized geometry point of view. We argue that the equivalence between the commutative and semiclassically noncommutative DBI actions is naturally encoded in the generalized geometry of D-branes.
Noncommutative Yang-Mills from equivalence of star products
International Nuclear Information System (INIS)
Jurco, B.; Schupp, P.
2000-01-01
It is shown that the transformation between ordinary and noncommutative Yang-Mills theory as formulated by Seiberg and Witten is due to the equivalence of certain star products on the D-brane world-volume. (orig.)
Noncommutative Yang-Mills from equivalence of star products
Energy Technology Data Exchange (ETDEWEB)
Jurco, B. [Max-Planck-Institut fuer Mathematik, Bonn (Germany); Schupp, P. [Sektion Physik, Universitaet Muenchen, Theresienstrasse 37, 80333 Muenchen (Germany)
2000-05-01
It is shown that the transformation between ordinary and noncommutative Yang-Mills theory as formulated by Seiberg and Witten is due to the equivalence of certain star products on the D-brane world-volume. (orig.)
String constraints on discrete symmetries in MSSM type II quivers
Energy Technology Data Exchange (ETDEWEB)
Anastasopoulos, Pascal [Technische Univ. Wien (Austria). Inst. fur Theor. Phys.; Cvetic, Mirjam [Univ. of Pennsylvania, Philadelphia PA (United States). Dept. of Physics and Astronomy; Univ. of Maribor (Slovenia). Center for Applied Mathematics and Theoretical Physics; Richter, Robert [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-11-15
We study the presence of discrete gauge symmetries in D-brane semirealistic compactifications. After establishing the constraints on the transformation behaviour of the chiral matter for the presence of a discrete gauge symmetry we perform a systematic search for discrete gauge symmetries within semi-realistic D-brane realizations, based on four D-brane stacks, of the MSSM and the MSSM with three right-handed neutrinos. The systematic search reveals that Proton hexality, a discrete symmetry which ensures the absence of R-parity violating terms as well as the absence of dangerous dimension 5 proton decay operators, is only rarely realized. Moreover, none of the semi-realistic local D-brane configurations exhibit any family dependent discrete gauge symmetry.
Phase of N=2 theories in 1+1 dimensions with boundary
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Herbst, M. [CERN, Geneva (Switzerland). Theory Division, Dept. of Physics; Hori, K.; Page, D. [Toronto Univ., ON (Canada). Dept. of Physics
2008-03-15
We study B-type D-branes in linear sigma models with Abelian gauge groups. The most important finding is the grade restriction rule. It classifies representations of the gauge group on the Chan-Paton factor, which can be used to define a family of D-branes over a region of the Kahler moduli space that connects special points of different character. As an application, we find a precise, transparent relation between D-branes in various geometric phases as well as free orbifold and Landau-Ginzburg points. The result reproduces and unifies many of the earlier mathematical results on equivalences of D-brane categories, including the McKay correspondence and Orlov's construction. (orig.)
Dirichlet branes and nonperturbative aspects of supersymmetric string and gauge theories
International Nuclear Information System (INIS)
Yin, Zheng
1999-01-01
In chapter 1 the author reviews some elements of string theory relevant to the rest of this report. He touches on both the classical, i.e. perturbative, string physics before D-branes rise to prominence, and some of the progresses they brought forth. In chapter 2 he proceeds to give an exact algebraic formulation of D-branes in curved spaces. This allows one to classify them in backgrounds of interest and study their geometric properties. He applies this formalism to string theory on Calabi-Yau and other supersymmetry preserving manifolds. Then he studies the behavior of the D-branes under mirror symmetry in chapter 3. Mirror symmetry is known to be a symmetry of string theory perturbatively. He finds evidence for its nonperturbative validity when D-branes are also considered and compute some dynamical consequences. In chapter 4 he turns to examine the consistency of curved and/or intersecting D-brane configurations. They have been used recently to extract information about the field theories that arise in certain limits. It turns out that there are potential quantum mechanical inconsistencies associated with them. What saves the day are certain subtle topological properties of D-branes. This resolution has implications for the conserved charges carried by the D-branes, which he computes for the cases studied in chapter 2. In chapter 5 he uses intersecting brane configurations to study three dimensional supersymmetric gauge theories. There is also a mirror symmetry there that, among other things, exchanges classical and quantum mechanical quantities of a (mirror) pair of theories. It has an elegant realization in term of a symmetry of string theory involving D-branes. The author employs it to study a wide class of 3d models. He also predicts new mirror pairs and unconventional 3d field theories without Lagrangian descriptions
Open string in the constant B-field background
International Nuclear Information System (INIS)
Jing Jian; Long Zhengwen
2005-01-01
A new method is proposed to quantize open strings in this paper. To illustrate our method, we analyze free open string as well as open string in the D-brane background with a nonvanishing B-field, respectively. The Poisson brackets among Fourier components are obtained firstly then we get the Poisson brackets among open string's coordinates. The noncommutativity of coordinates along the D-brane is reproduced. Some ambiguities in the previous discussions can be avoided
Energy Technology Data Exchange (ETDEWEB)
Valdez U, J J; Pichardo M, P A; Cortes M, G; Escudero de los Rios, P. [Hospital de Oncologia. Centro Medico Nacional Siglo XXI. IMSS, Mexico D.F. (Mexico)
2005-07-01
The obtained results in presently study demonstrate that the feasibility of the detection of the sentry ganglion in cervix uterine cancer using a boarding by laparoscopic via, being necessary the use of twice labelled as much with patent blue and radioisotope (colloid of labelled rhenium with {sup 99m}Tc, total dose of 3 MCi) to achieve the identification of the ganglion. (Author)
1998-07-09
highly resistive to void swelling. According to positron annihilation studies [1] the onset of vacancy long-range mi- gration is almost not affected...transformations in the chemical composition of the dispersoids. Two different types of the TiO2 particles depending on Cr behaviour are found to form...in the steel in the course of annealing. In the first case, Cr enriches mainly in nearest subsurface layers of the TiO2 dispersoids. In the second
Directory of Open Access Journals (Sweden)
Géraldine Daneau
2016-01-01
Conclusion: RODAC plates detect mycobacteria at low numbers of microorganisms. In addition, this method allowed us to show that 70% ethanol does not reliably kill mycobacteria when applied for 5min to a dried surface, and that MTB bacilli may arrive outside a Class II BSC during routine practice, although the route could not be documented.
1975-06-30
within YPG/LWBGR is largely transient and consists primarily of military, civil service, and contractual personnel totaling approximately 2000... Ingeneria Antisimica, Santiago, Chile, 1, p. 14-27. Algermissen, S. T., and Perkins, D. M., 1972, Technique for seismic zoning: general consideration...T P -- m.. SIA~gUN,. ,.. A- 45 SOURCES OF PERSONAL COMMUNICATION Ashley, John F., Civil Engineer, 58th Civil Engineer Squadron, Luke Air Force Base
Kuragano, Masahiro; Murakami, Yota; Takahashi, Masayuki
2018-03-25
Nonmuscle myosin II (NMII) plays an essential role in directional cell migration. In this study, we investigated the roles of NMII isoforms (NMIIA and NMIIB) in the migration of human embryonic lung fibroblasts, which exhibit directionally persistent migration in an intrinsic manner. NMIIA-knockdown (KD) cells migrated unsteadily, but their direction of migration was approximately maintained. By contrast, NMIIB-KD cells occasionally reversed their direction of migration. Lamellipodium-like protrusions formed in the posterior region of NMIIB-KD cells prior to reversal of the migration direction. Moreover, NMIIB KD led to elongation of the posterior region in migrating cells, probably due to the lack of load-bearing stress fibers in this area. These results suggest that NMIIA plays a role in steering migration by maintaining stable protrusions in the anterior region, whereas NMIIB plays a role in maintenance of front-rear polarity by preventing aberrant protrusion formation in the posterior region. These distinct functions of NMIIA and NMIIB might promote intrinsic and directed migration of normal human fibroblasts. Copyright © 2018 Elsevier Inc. All rights reserved.
DEFF Research Database (Denmark)
Stone, Gregg W; Mehran, Roxana; Goldstein, Patrick
2015-01-01
BACKGROUND: In the HORIZONS-AMI (Harmonizing Outcomes with RevasculariZatiON and Stents in Acute Myocardial Infarction) trial, 3,602 patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) treated with bivalirudin had lower......, 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....... Bivalirudin resulted in increased acute (events were lower with bivalirudin (8.8% vs. 11.9%; RR: 0.74; 95% CI: 0...
Brzoska, Tomasz; Suzuki, Yuko; Mogami, Hideo; Sano, Hideto; Urano, Tetsumei
2013-01-01
Recently, by employing intra-vital confocal microscopy, we demonstrated that platelets expose phosphatidylserine (PS) and fibrin accumulate only in the center of the thrombus but not in its periphery. To address the question how exposure of platelet anionic phospholipids is regulated within the thrombus, an in-vitro experiment using diluted platelet-rich plasma was employed, in which the fibrin network was formed in the presence of platelets, and PS exposure on the platelet surface was analyz...
Superstrings in type IIB R-R plane-wave in semi-light-cone gauge and conformal invariance
International Nuclear Information System (INIS)
Mukhopadhyay, Partha
2009-01-01
We reconsider the analysis done by Kazama and Yokoi in arXiv:0801.1561 (hep-th). We find that although the right vacuum of the theory is the one associated to massless normal ordering (MNO), phase space normal ordering (PNO) plays crucial role in the analysis in the following way. While defining the quantum energy-momentum (EM) tensor one needs to take into account the field redefinition relating the space-time field and the corresponding world-sheet coupling. We argue that for a simple off-shell ansatz for the background this field redefinition can be taken to be identity if the interaction term is ordered according to PNO. This definition reproduces the correct physical spectrum when the background is on-shell. We further show that the right way to extract the effective equation of motion from the Virasoro anomaly is to first order the anomaly terms according to PNO at a finite regularization parameter ε and then take the ε → 0 limit. This prescription fixes an ambiguity in taking the limit for certain bosonic and fermionic contributions to the Virasoro anomaly and is the natural one to consider given the above definition of the EM tensor.
Panés, Julian; Sandborn, William J.; Schreiber, Stefan; Sands, Bruce E.; Vermeire, Séverine; D'Haens, Geert; Panaccione, Remo; Higgins, Peter D. R.; Colombel, Jean-Frederic; Feagan, Brian G.; Chan, Gary; Moscariello, Michele; Wang, Wenjin; Niezychowski, Wojciech; Marren, Amy; Healey, Paul; Maller, Eric
2017-01-01
Tofacitinib is an oral, small-molecule Janus kinase inhibitor that is being investigated for IBD. We evaluated the efficacy and safety of tofacitinib for induction and maintenance treatment in patients with moderate-to-severe Crohn's disease (CD). We conducted two randomised, double-blind,
International Nuclear Information System (INIS)
Valdez U, J.J.; Pichardo M, P.A.; Cortes M, G.; Escudero de los Rios, P.
2005-01-01
The obtained results in presently study demonstrate that the feasibility of the detection of the sentry ganglion in cervix uterine cancer using a boarding by laparoscopic via, being necessary the use of twice labelled as much with patent blue and radioisotope (colloid of labelled rhenium with 99m Tc, total dose of 3 MCi) to achieve the identification of the ganglion. (Author)
Pre-potential in the AdS{sub 5}×S{sup 5} type IIB superspace
Energy Technology Data Exchange (ETDEWEB)
Poláček, Martin; Siegel, Warren [C.N. Yang Institute for Theoretical Physics, State University of New York,100 Nicolls Rd., Stony Brook, NY 11794-3840 (United States)
2017-01-16
We found the pre-potential in the superspace with AdS{sub 5} × S{sup 5} background. The pre-potential appears as part of the vielbeins, without derivatives. In both subspaces (AdS{sub 5} and S{sup 5}) we used Poincaré coordinates. We picked one bulk coordinate in AdS{sub 5} and one bulk coordinate in S{sup 5} to define the space-cone gauge. Such space-cone gauge destroys the bulk Lorentz covariance. However, it still preserves boundary Lorentz covariance (and gives projective superspace) SO(3,1)⊗SO(4) and so symmetries of boundary CFT are manifest.