554 research outputs found
BPS black holes, quantum attractor flows and automorphic forms
We propose a program for counting microstates of four-dimensional BPS black
holes in N >= 2 supergravities with symmetric-space valued scalars by
exploiting the symmetries of timelike reduction to three dimensions. Inspired
by the equivalence between the four dimensional attractor flow and geodesic
flow on the three-dimensional scalar manifold, we radially quantize stationary,
spherically symmetric BPS geometries. Connections between the topological
string amplitude, attractor wave function, the Ooguri-Strominger-Vafa
conjecture and the theory of automorphic forms suggest that black hole
degeneracies are counted by Fourier coefficients of modular forms for the
three-dimensional U-duality group, associated to special "unipotent"
representations which appear in the supersymmetric Hilbert space of the quantum
attractor flow.Comment: 9 pages, revtex; v2: references added and typos correcte
EM BUSCA DOS PRINCĂPIOS DA GESTĂO DA QUALIDADE TOTAL EM SERVIĂOS DE PROJETO DE ARQUITETURA: DESTAQUES DA TURQUIA
Proposal: Architectural design companies increasingly recognize that time spent on management is not at the expense of their production and there are always better ways to organize business. Although architects have long placed a traditional emphasis on quality, quality management is still a new concept for the majority of architectural design companies, which have to organize relatively more complicated operations nowadays to meet their clientsâ expectations. This study aims to understand how architectural design companies define quality and explores the extent to which Total Quality Management (TQM) principles like continual improvement, employee involvement, customer satisfaction and others can be pertinent in these companies. Adopting a qualitative research strategy, the authors interviewed with the owner-managers of 10 widely-recognized architectural design companies of different size in Istanbul. The results from the content analysis of semi-structured interview data suggest that i) TQM principles cannot be directly applied in architectural design companies without an appropriate translation; ii) special characteristics of design services are important to explain quality-related perceptions of owner-managers; iii) the owner-managers feel the pressure from the changing internal and external environmental conditions, however few of them adopt a systematic and documented approach to quality management. Architectural design offices which aim to establish a quality management system can benefit from this study to understand potential problem areas on their road.As empresas de projeto de arquitetura cada vez mais reconhecem que o tempo dedicado Ă gestĂŁo nĂŁo onera a sua produção e que hĂĄ sempre maneiras de organizar melhor as atividades empresariais. Embora arquitetos tenham colocado durante muito tempo uma ĂȘnfase tradicional na qualidade, a gestĂŁo da qualidade ainda Ă© um conceito novo para a maioria das empresas de projeto de arquitetura, que, hoje em dia, tĂȘm de organizar operaçÔes relativamente mais complicadas para atender Ă s expectativas de seus clientes. Este estudo visa compreender de que modo as empresas de projeto de arquitetura definem qualidade e exploram os limites nos quais os princĂpios da gestĂŁo da qualidade total (TQM), como melhoria contĂnua, envolvimento dos funcionĂĄrios, satisfação do cliente e outros, podem ser pertinentes para essas empresas. Adotando uma estratĂ©gia de pesquisa qualitativa, os autores entrevistaram os proprietĂĄrios-gerentes de 10 empresas de projeto de arquitetura amplamente reconhecidas, de diferentes tamanhos, em Istambul. Os resultados da anĂĄlise de conteĂșdo dos dados de entrevistas semi-estruturadas sugerem que: i) os princĂpios do TQM nĂŁo podem ser aplicados diretamente em empresas de projeto de arquitetura, sem uma tradução adequada; ii) as caracterĂsticas especiais dos serviços de projeto sĂŁo importantes para explicar as percepçÔes de proprietĂĄrios-gerentes relacionadas Ă qualidade; iii) os proprietĂĄrios-gerentes sentem a pressĂŁo da mudança interna e externa das condiçÔes ambientais, porĂ©m poucos deles adotam uma abordagem sistemĂĄtica e documentada para a gestĂŁo da qualidade. Empresas de projeto de arquitetura que tĂȘm como objetivo estabelecer um sistema de gestĂŁo da qualidade podem se beneficiar deste estudo para conhecer as ĂĄreas potencialmente problemĂĄticas que encontrarĂŁo
Fake Supergravity and Domain Wall Stability
We review the generalized Witten-Nester spinor stability argument for flat
domain wall solutions of gravitational theories. Neither the field theory nor
the solution need be supersymmetric. Nor is the space-time dimension
restricted. We develop the non-trivial extension required for AdS-sliced domain
walls and apply this to show that the recently proposed "Janus" solution of
Type IIB supergravity is stable non-perturbatively for a broad class of
deformations. Generalizations of this solution to arbitrary dimension and a
simple curious linear dilaton solution of Type IIB supergravity are byproducts
of this work.Comment: 37 pages, 3 figures, v2: minor corrections, references and
acknowledgments adde
Geometry of The Embedding of Supergravity Scalar Manifolds in D=11 and D=10
Several recent papers have made considerable progress in proving the
existence of remarkable consistent Kaluza-Klein sphere reductions of D=10 and
D=11 supergravities, to give gauged supergravities in lower dimensions. A proof
of the consistency of the full gauged SO(8) reduction on S^7 from D=11 was
given many years ago, but from a practical viewpoint a reduction to a smaller
subset of the fields can be more manageable, for the purposes of lifting
lower-dimensional solutions back to the higher dimension. The major complexity
of the spherical reduction Ansatze comes from the spin-0 fields, and of these,
it is the pseudoscalars that are the most difficult to handle. In this paper we
address this problem in two cases. One arises in a truncation of SO(8) gauged
supergravity in four dimensions to U(1)^4, where there are three pairs of
dilatons and axions in the scalar sector. The other example involves the
truncation of SO(6) gauged supergravity in D=5 to a subsector containing a
scalar and a pseudoscalar field, with a potential that admits a second
supersymmetric vacuum aside from the maximally-supersymmetric one. We briefly
discuss the use of these emdedding Ansatze for the lifting of solutions back to
the higher dimension.Comment: Latex, 24 pages, typos correcte
Four Dimensional Conformal Supergravity From AdS Space
Exploring the role of conformal theories of gravity in string theory, we show
that the minimal (N=2) gauged supergravities in five dimensions induce the
multiplets and transformations of N=1 four dimensional conformal supergravity
on the spacetime boundary. N=1 Poincare supergravity can be induced by
explicitly breaking the conformal invariance via a radial cutoff in the 5d
space. The AdS/CFT correspondence relates the maximal gauged supergravity in
five dimensions to N=4 super Yang-Mills on the 4d spacetime boundary. In this
context we show that the conformal anomaly of the gauge theory induces
conformal gravity on the boundary of the space and that this theory, via the
renormalization group, encapsulates the gravitational dynamics of the skin of
asymptotically AdS spacetimes. Our results have several applications to the
AdS/CFT correspondence and the Randall-Sundrum scenario.Comment: 20 pages, LaTeX. v3. references and minor comments adde
Multi-black holes from nilpotent Lie algebra orbits
For N \ge 2 supergravities, BPS black hole solutions preserving four
supersymmetries can be superposed linearly, leading to well defined solutions
containing an arbitrary number of such BPS black holes at arbitrary positions.
Being stationary, these solutions can be understood via associated non-linear
sigma models over pseudo-Riemaniann spaces coupled to Euclidean gravity in
three spatial dimensions. As the main result of this paper, we show that
whenever this pseudo-Riemanniann space is an irreducible symmetric space G/H*,
the most general solutions of this type can be entirely characterised and
derived from the nilpotent orbits of the associated Lie algebra Lie(G). This
technique also permits the explicit computation of non-supersymmetric extremal
solutions which cannot be obtained by truncation to N=2 supergravity theories.
For maximal supergravity, we not only recover the known BPS solutions depending
on 32 independent harmonic functions, but in addition find a set of non-BPS
solutions depending on 29 harmonic functions. While the BPS solutions can be
understood within the appropriate N=2 truncation of N=8 supergravity, the
general non-BPS solutions require the whole field content of the theory.Comment: Corrected version for publication, references adde
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