2,043 research outputs found
Stability and Thermodynamics of AdS Black Holes with Scalar Hair
Recently a class of static spherical black hole solutions with scalar hair
was found in four and five dimensional gauged supergravity with modified, but
AdS invariant boundary conditions. These black holes are fully specified by a
single conserved charge, namely their mass, which acquires a contribution from
the scalar field. Here we report on a more detailed study of some of the
properties of these solutions. A thermodynamic analysis shows that in the
canonical ensemble the standard Schwarzschild-AdS black hole is stable against
decay into a hairy black hole. We also study the stability of the hairy black
holes and find there always exists an unstable radial fluctuation, in both four
and five dimensions. We argue, however, that Schwarzschild-AdS is probably not
the endstate of evolution under this instability.Comment: 18 pages, 4 figure
Violation of Energy Bounds in Designer Gravity
We continue our study of the stability of designer gravity theories, where
one considers anti-de Sitter gravity coupled to certain tachyonic scalars with
boundary conditions defined by a smooth function W. It has recently been argued
there is a lower bound on the conserved energy in terms of the global minimum
of W, if the scalar potential arises from a superpotential P and the scalar
reaches an extremum of P at infinity. We show, however, there are
superpotentials for which these bounds do not hold.Comment: 16 pages, 4 figures, v2: discussion of vacuum decay included, typos
corrected, reference adde
Particle Production near an AdS Crunch
We numerically study the dual field theory evolution of five-dimensional
asymptotically anti-de Sitter solutions of supergravity that develop
cosmological singularities. The dual theory is an unstable deformation of the N
= 4 gauge theory on R S3, and the big crunch singularity in the bulk
occurs when a boundary scalar field runs to infinity. Consistent quantum
evolution requires one imposes boundary conditions at infinity. Modeling these
by a steep regularization of the scalar potential, we find that when an
initially nearly homogeneous wavepacket rolls down the potential, most of the
potential energy of the initial configuration is converted into gradient energy
during the first oscillation of the field. This indicates there is no
transition from a big crunch to a big bang in the bulk for dual boundary
conditions of this kind.Comment: 20 pages, 6 figure
Origin of Spin Ice Behavior in Ising Pyrochlore Magnets with Long Range Dipole Interactions: an Insight from Mean-Field Theory
Recent experiments suggest that the Ising pyrochlore magnets and display qualitative
properties of the ferromagnetic nearest neighbor spin ice model proposed by
Harris {\it et al.}, Phys. Rev. Lett. {\bf 79}, 2554 (1997). The manifestation
of spin ice behavior in these systems {\it despite} the energetic constraints
introduced by the strength and the long range nature of dipole-dipole
interactions, remains difficult to understand. We report here results from a
mean field analysis that shed some light on the origin of spin ice behavior in
(111) Ising pyrochlores. Specifically, we find that there exist a large
frustrating effect of the dipolar interactions beyond the nearest neighbor, and
that the degeneracy established by effective ferromagnetic nearest neighbor
interactions is only very weakly lifted by the long range interactions. Such
behavior only appears beyond a cut-off distance corresponding to
nearest neighbor. Our mean field analysis shows that truncation of dipolar
interactions leads to spurious ordering phenomena that change with the
truncation cut-off distance.Comment: 7 Color POSTSCRIPT figures included. To appear in Canadian Journal of
Physics for the Proceedings of the {\it Highly Frustrated Magnetism 2000
Conference}, Waterloo, Ontario, Canada, June 11-15, 2000 Contact:
[email protected]
Multinationals are Multicultural Units: Some Indications from a Cross-Cultural Study
This paper makes a case for the value of looking at culture and multinationals from a management and organizational perspective because it is one which could direct greater attention towards culture as a significant factor in future investigation on multinational corporations. We attempt to illustrate that multinationals are fundamentally multicultural units in more ways than one. This paper is based on selected materials from a qualitative study of culture and learning in organizations and management. The study investigated four selected Dutch firms in Thailand using evidences collected through observations and open-ended interviews. All evidences were analysed under grounded theory procedure. Parts of the evidences and theorization from the study are presented in this paper, which begins with two cultural riddles from one of the cases as a backdrop for subsequent discussions. Following the riddles is an abridge version of the key finding of the study-a grounded theory of cross-cultural intelligence. Then the two riddles are revisited, this time to illustrate how the proposed theory could illuminate an understanding of their covert meanings vis-Ã -vis culture and learning in multinationals. Last, we reinstate how our study and its theoretical and empirical findings can elucidate the central thesis that multinationals are essentially multicultural units.case study, culture, corporate culture, cultural intelligence, multinationals, Netherlands, Thailand
Portrait of an Odd-Eyed Cat: Cultural Crossing as a Trademark for a Dutch-Thai Strategic Alliance
This chapter attempts a step forward in seeking a richer understanding of the dynamics of strategic alliances, specifically when viewed from a cross-cultural perspective. We report selected materials from a study designed to build a theory of culture and learning in organizations based on observations of and open-ended interviews with Dutch and Thai employees working for four selected Dutch firms in Thailand. Here we present one of those cases, a Dutch-Thai joint venture that thrived by weaving together the many intricate cultural webs to achieve a unique pattern of partnership which, metaphorically speaking, became its indispensible trademark. The case illustrates how the three levels of culture – national, organizational, and professional cultures – could all interlace in a real world setting and serve as an instrumental force of success amidst tension in one particular cross-border strategic alliance. First, we adopt a thick descriptive style of case narration to present the case of a Dutch- Thai joint venture, Chuchawal-De Weger Internationaal (CDW), painting a portrait of its origin, evolution and characteristics. Next, we turn to elaborate on the particular issue of cultural crossing, its exact theorized properties, dimensions and implications. Finally, we relate the case of CDW to the proposed theory and conclude with a reflection on how this case and our interpretation of it illuminate the complex role culture can play in the dynamics of strategic alliances.cross-cultural management, culture, qualitative case study, strategic alliance, thick-description
Populating the Landscape: A Top Down Approach
We put forward a framework for cosmology that combines the string landscape
with no boundary initial conditions. In this framework, amplitudes for
alternative histories for the universe are calculated with final boundary
conditions only. This leads to a top down approach to cosmology, in which the
histories of the universe depend on the precise question asked. We study the
observational consequences of no boundary initial conditions on the landscape,
and outline a scheme to test the theory. This is illustrated in a simple model
landscape that admits several alternative inflationary histories for the
universe. Only a few of the possible vacua in the landscape will be populated.
We also discuss in what respect the top down approach differs from other
approaches to cosmology in the string landscape, like eternal inflation.Comment: 22 pages, 1 figur
Phase transitions near black hole horizons
The Reissner-Nordstrom black hole in four dimensions can be made unstable
without violating the dominant energy condition by introducing a real massive
scalar with non-renormalizable interactions with the gauge field. New stable
black hole solutions then exist with greater entropy for fixed mass and charge
than the Reissner-Nordstrom solution. In these new solutions, the scalar
condenses to a non-zero value near the horizon. Various generalizations of
these hairy black holes are discussed, and an attempt is made to characterize
when black hole hair can occur.Comment: 30 pages, 6 figures. v2: minor corrections, references adde
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