Three-dimensional black holes from deformed anti-de Sitter

We present new exact three-dimensional black-string backgrounds, which contain both NS--NS and electromagnetic fields, and generalize the BTZ black holes and the black string studied by Horne and Horowitz. They are obtained as deformations of the Sl(2,R) WZW model. Black holes resulting from purely continuous deformations possess true curvature singularities. When discrete identifications are introduced, extra chronological singularities appear, which under certain circumstances turn out to be naked. The backgrounds at hand appear in the moduli space of the Sl(2,R) WZW model. Hence, they provide exact string backgrounds and allow for a more algebraical CFT description. This makes possible the determination of the spectrum of primaries.Comment: JHEP style, 33 pages, 1 figur

To imitate or differentiate: Cross-level identity work in an innovation network

Survival in global high-tech industries requires many organizations to participate in specialized innovation networks. However, sustained participation in these networks often proves more challenging than expected for organizations and their representatives, due to complex cross-level identity tensions that are indiscernible when only one level of analysis is considered. The purpose of this study is to analyze cross-level identity tensions at the interface of personal and organizational identities in an innovation network. We identify three key cross-level identity tensions related to intellectual property, communication and market definition, which together contribute to an overall organizational-personal identity tension opposing differentiation and imitation. These tensions are indicative of a complex process of “partial isomorphism” in identity work, which can facilitate collaboration while simultaneously fostering innovation among personal and organizational network members

Comments on geometric and universal open string tachyons near fivebranes

In a recent paper (hep-th/0703157), Sen studied unstable D-branes in NS5-branes backgrounds and argued that in the strong curvature regime the universal open string tachyon (on D-branes of the wrong dimensionality) and the geometric tachyon (on D-branes that are BPS in flat space but not in this background) may become equivalent. We study in this note an example of a non-BPS suspended D-brane vs. a BPS D-brane at equal distance between two fivebranes. We use boundary worldsheet CFT methods to show that these two unstable branes are identical.Comment: 8 pages, 1 figure; ver. 2 to appear in JHEP: one comment, refs and appendices adde

Non-Abelian coset string backgrounds from asymptotic and initial data

We describe hierarchies of exact string backgrounds obtained as non-Abelian cosets of orthogonal groups and having a space--time realization in terms of gauged WZW models. For each member in these hierarchies, the target-space backgrounds are generated by the ``boundary'' backgrounds of the next member. We explicitly demonstrate that this property holds to all orders in $\alpha'$. It is a consequence of the existence of an integrable marginal operator build on, generically, non-Abelian parafermion bilinears. These are dressed with the dilaton supported by the extra radial dimension, whose asymptotic value defines the boundary. Depending on the hierarchy, this boundary can be time-like or space-like with, in the latter case, potential cosmological applications.Comment: 26 page

Specialization and Values as Inputs to Decision-Making Mining Managers

L'objet du présent article est de découvrir ce que les dirigeants de l'industrie minière au Canada considèrent comme le plus important pour la direction de leurs entreprises. En d'autres termes, à quel système de valeurs se réfèrent-ils? S'intéressent-ils davantage aux personnes qu'aux choses matérielles?Pour tenter de répondre à ces questions, l'auteur s'est inspiré de deux modèles d'analyse de comportement: l'un mis au point par England et ses collègues, fondé sur les valeurs de jugement personnel, l'autre appuyé sur la théorie de Frost et de Barnowe où il s'agit de savoir si les intéressés sont portés plutôt vers les choses que les personnes.L'enquête fut faite à partir d'une liste de 594 membres de l'Institut canadien des mines et de la métallurgie en Colombie Britannique en Alberta et dans le territoire du Yukon. Il faut aussi noter que l'enquête porte sur les dirigeants d'entreprises situées dans des petits centres miniers. On a transmis par la poste à ces gens un questionnaire se rapportant à 66 concepts et 189 ont effectivement répondu.Lorsque les données de cette enquête furent compilées, elles ont donné le résultat suivant: selon le système mis au point par England, 76 des 189 répondants ou 38% pouvaient être considérés comme essentiellement pragmatiques, 65 ou 35% de ces dirigeants fondaient leurs attitudes sur un corps d'idées arrêtées, 4% étaient plutôt de type affectif et 22% avaient une orientation plutôt mélangée. D'autre part, suivant la théorie de Frost et Barnowe, ces dirigeants se partageaient en deux groupes principaux. On pouvait classer 67 d'entre eux parmi les « généralistes », c'est-à-dire qu'ils portaient autant d'attention aux personnes qu'aux choses; 79 d'entre eux s'intéressaient strictement aux questions d'ordre matériel; 13 mettaient l'accent sur la personne et 22 pouvaient être rangés dans une catégorie que l'auteur désigne sous le nom de « non-spécialistes ».De l'étude ci-dessus, on peut tirer deux conclusions:En premier lieu, les gérants de sociétés minières canadiennes, dans les petits centres, se préoccupent principalement du fonctionnement de l'entreprise et ils ne s'intéressent guère aux valeurs sociales d'ensemble, bien-être des travailleurs, environnement, etc.. Ce sont des technologues intéressés à leur travail pour qui l'exercice de leur tâche est d'importance primordiale.Deuxièmement, les différences d'orientation entre eux reposent sur la perception qu'ils se font du travail humain. Ceci se vérifie davantage chez ceux qui ont été obligés de prendre des décisions majeures se rapportant aux travailleurs et au rôle que ceux-ci tiennent dans l'entreprise.This thrust of this paper is to explore the objectives which mining managers perceive as important for effective organizational functioning in terms of their values, of the sense they make of the world around them in two specific, fundamental areas, orientation toward people and toward things, and of the interaction between managerial values and this orientation

Non-Critical String Duals of N=1 Quiver Theories

We construct N=1 non-critical strings in four dimensions dual to strongly coupled N=1 quiver gauge theories in the Coulomb phase, generalizing the string duals of Argyres-Douglas points in N=2 gauge theories. They are the first examples of superstrings vacua with an exact worldsheet description dual to chiral N=1 theories. We identify the dual of the non-critical superstring using a brane setup describing the field theory in the classical limit. We analyze the spectrum of chiral operators in the strongly coupled regime and show how worldsheet instanton effects give non-perturbative information about the gauge theory. We also consider aspects of D-branes relevant for the holographic duality.Comment: JHEP style; 40 pages, 3 figures; v2: minor corrections, refs added, version to appear in JHE

AdS2xS2 as an exact heterotic string background

An exact heterotic string theory on an AdS2xS2 background supported by an electromagnetic flux is found as a marginal deformation of an SL(2,R)xSU(2) WZW model. Based on a talk given at NATO Advanced Study Institute and EC Summer School on String Theory: from Gauge Interactions to Cosmology, Cargese, Corsica, France, 7 Jun - 19 Jun 2004.Comment: 5 page

Quantification of the white noise component in accelerometer and gyrometer output signals using the Allan variance method

The so–called «Allan variance method» is a well–known tool extensively used in the discrimination and characterization of nois e components in precision oscillators . Theoretical properties are discussed in this paper and it is shown how they can be utilized to adapt the tool to the analysis of inertial sensors signals . Furthermore, a figure of merit expressed in terms of mean and variance i s presented to quantify the performance of the method, and, an empirical formula for the probability density function is proposed . An example of application is then given where the method is applied to real accelerometer and gyrometer outputs to evaluat e their white noise component .La méthode dite de la variance d'Allan est un outil couramment utilisé pour discriminer et caractériser différentes composantes de bruits intervenant dans les oscillateurs de précision. Cet article présente une approche théorique des propriétés de la méthode et montre comment elles peuvent être utilisées afin d'adapter l'outil pour l'analyse de signaux de capteurs inertiels. De plus, nous avons déterminé un indice de qualité de l'outil en terme de moyenne et de variance et nous proposons une expression empirique de sa densité de probabilité. Cette étude est enfin étayée par l'évaluation de la composante blanche de signaux accélérométriques et gyrométriques réels

D-branes in Lorentzian AdS(3)

We study the exact construction of D-branes in Lorentzian AdS(3). We start by defining a family of conformal field theories that gives a natural Euclidean version of the SL(2,R) CFT and does not correspond to H(3)+, the analytic continuation of AdS(3). We argue that one can recuperate the exact CFT results of Lorentzian AdS(3), upon an analytic continuation in the moduli space of these conformal field theories. Then we construct exact boundary states for various symmetric and symmetry-breaking D-branes in AdS(3).Comment: JHEP style;21 pages, no figures; v2:some corrections, comments and references adde

Brane Dynamics and 3D Seiberg Duality on the Domain Walls of 4D N=1 SYM

We study a three-dimensional U(k) Yang-Mills Chern-Simons theory with adjoint matter preserving two supersymmetries. According to Acharya and Vafa, this theory describes the low-energy worldvolume dynamics of BPS domain walls in four-dimensional N=1 SYM theory. We demonstrate how to obtain the same theory in a brane configuration of type IIB string theory that contains threebranes and fivebranes. A combination of string and field theory techniques allows us to re-formulate some of the well-known properties of N=1 SYM domain walls in a geometric language and to postulate a Seiberg-like duality for the Acharya-Vafa theory. In the process, we obtain new information about the dynamics of branes in setups that preserve two supersymmetries. Using similar methods we also study other N=1 CS theories with extra matter in the adjoint and fundamental representations of the gauge group.Comment: 25 pages, 5 figure