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287,998
Hierarchies from Fluxes in String Compactifications
, 2002
"... Warped compactifications with significant warping provide one of the few known mechanisms for naturally generating large hierarchies of physical scales. We demonstrate that this mechanism is realizable in string theory, and give examples involving orientifold compactifications of IIB string theory a ..."
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Cited by 724 (33 self)
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and Ftheory compactifications on CalabiYau fourfolds. In each case, the hierarchy of scales is fixed by a choice of RR and NS fluxes in the compact manifold. Our solutions involve compactifications of the KlebanovStrassler gravity dual to a confining N = 1 supersymmetric gauge theory
Human domination of Earth’s ecosystems
 Science
, 1997
"... Human alteration of Earth is substantial and growing. Between onethird and onehalf interact with the atmosphere, with aquatic of the land surface has been transformed by human action; the carbon dioxide con systems, and with surrounding land. Morecentration in the atmosphere has increased by near ..."
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Cited by 551 (6 self)
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Human alteration of Earth is substantial and growing. Between onethird and onehalf interact with the atmosphere, with aquatic of the land surface has been transformed by human action; the carbon dioxide con systems, and with surrounding land. Morecentration in the atmosphere has increased by nearly 30 percent since the beginning of over, land trallsformation interacts strongly the Industrial Revolution; more atmospheric nitrogen is fixed by humanity than by all with most other components of global ennatural terrestrial sources combined; more than half of all accessible surface fresh water rironmental change. is put to use by humanity; and about onequarter of the bird species on Earth have been The measurement of land transformadriven to extinction. By these and other standards, it is clear that we live on a human tion on a global scale is challenging; changdominated planet. es can be measured more or less straightforwardly at a eiven site, but it is difficult to aggregate these changes regionally and globallv. In contrast to analvses of human alA11 organisms modify their environment, reasonably well quantified; all are ongoing, teraiion of the global carbon cycle, we and humans are no exceotion. As the hu These relativelv welldocumented changes cannot install instruments on a tro~ical man population has and the power of in turn entrail; further alterations to;he mountain to collect evidence of land tianstechnology has expanded, the scope and f~~nctioning of the Earth system, most no formation. Remote sensing is a most useful
Strategies of Discourse Comprehension
, 1983
"... El Salvador, Guatemala is a, study in black and white. On the left is a collection of extreme MarxistLeninist groups led by what one diplomat calls “a pretty faceless bunch of people.’ ’ On the right is an entrenched elite that has dominated Central America’s most populous country since a CIAbacke ..."
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Cited by 601 (27 self)
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El Salvador, Guatemala is a, study in black and white. On the left is a collection of extreme MarxistLeninist groups led by what one diplomat calls “a pretty faceless bunch of people.’ ’ On the right is an entrenched elite that has dominated Central America’s most populous country since a CIA
The predictability of advectiondominated fluxtransport solar dynamo models
"... Space weather is a matter of practical importance in our modern society. Predictions of forecoming solar cycles mean amplitude and duration are currently being made based on fluxtransport numerical models of the solar dynamo. Interested in the forecast horizon of such studies, we quantify the pre ..."
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the predictability window of a representative, advectiondominated, fluxtransport dynamo model by investigating its sensitivity to initial conditions and control parameters through a perturbation analysis. We measure the rate associated with the exponential growth of an initial perturbation of the model trajectory
Unified analysis of discontinuous Galerkin methods for elliptic problems
 SIAM J. Numer. Anal
, 2001
"... Abstract. We provide a framework for the analysis of a large class of discontinuous methods for secondorder elliptic problems. It allows for the understanding and comparison of most of the discontinuous Galerkin methods that have been proposed over the past three decades for the numerical treatment ..."
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Cited by 519 (31 self)
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Abstract. We provide a framework for the analysis of a large class of discontinuous methods for secondorder elliptic problems. It allows for the understanding and comparison of most of the discontinuous Galerkin methods that have been proposed over the past three decades for the numerical treatment of elliptic problems.
Fronts propagating with curvature dependent speed: algorithms based on Hamilton–Jacobi formulations
 Journal of Computational Physics
, 1988
"... We devise new numerical algorithms, called PSC algorithms, for following fronts propagating with curvaturedependent speed. The speed may be an arbitrary function of curvature, and the front can also be passively advected by an underlying flow. These algorithms approximate the equations of motion, w ..."
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Cited by 1183 (64 self)
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We devise new numerical algorithms, called PSC algorithms, for following fronts propagating with curvaturedependent speed. The speed may be an arbitrary function of curvature, and the front can also be passively advected by an underlying flow. These algorithms approximate the equations of motion, which resemble HamiltonJacobi equations with parabolic righthandsides, by using techniques from the hyperbolic conservation laws. Nonoscillatory schemes of various orders of accuracy are used to solve the equations, providing methods that accurately capture the formation of sharp gradients and cusps in the moving fronts. The algorithms handle topological merging and breaking naturally, work in any number of space dimensions, and do not require that the moving surface be written as a function. The methods can be also used for more general HamiltonJacobitype problems. We demonstrate our algorithms by computing the solution to a variety of surface motion problems. 1
Designing Learning
 In
, 2004
"... …Truth [is] being involved in an eternal conversation about things that matter, conducted with passion and discipline…truth is not in the conclusions so much as in the process of conversation itself…if you want to be in truth you must be in conversation. Parker Palmer ..."
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Cited by 555 (9 self)
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…Truth [is] being involved in an eternal conversation about things that matter, conducted with passion and discipline…truth is not in the conclusions so much as in the process of conversation itself…if you want to be in truth you must be in conversation. Parker Palmer
Macroscopic strings as heavy quarks in large N gauge theory and Antide Sitter supergravity
 PHYS. J. C22
"... Maldacena has put forward large N correspondence between superconformal field theories on the brane and antide Sitter supergravity in spacetime. We study some aspects of the correspondence between N = 4 superconformal gauge theory on D3brane and maximal supergravity on adS5 × S5 by introducing mac ..."
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Cited by 510 (1 self)
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Maldacena has put forward large N correspondence between superconformal field theories on the brane and antide Sitter supergravity in spacetime. We study some aspects of the correspondence between N = 4 superconformal gauge theory on D3brane and maximal supergravity on adS5 × S5 by introducing macroscopic strings as heavy (anti)quark probes. The macroscopic strings are semiinfinite Type IIB strings ending on D3brane worldvolume. We first study deformation and fluctuation of D3brane when a macroscopic BPS string is attached. We find that both dynamics and boundary conditions agree with those for macroscopic string in antide Sitter supergravity. As a byproduct we clarify how Polchinski’s Dirichlet and Neumann open string boundary conditions arise. We then study nonBPS macroscopic string antistring pair configuration as physical realization of heavy quark Wilson loop. We obtain Q ¯ Q static potential and again find agreements between the gauge theory and the supergravity results. By turning on RamondRamond zeroform potential, we also study θ vacuum angle dependence of the static potential. We finally discuss dynamical realization of loop equation via turning on local electric field and recoil of heavy quark thereof, and of heavy baryon via of Nprong string junction. Throughout comparisons of the correspondence, we emphasize crucial role played by ‘geometric duality ’ between coordinates perpendicular to D3brane and parallel ones, hinting a possible explanation of emergence of the entire adS5 spacetime.
Quantum Gravity
, 2004
"... We describe the basic assumptions and key results of loop quantum gravity, which is a background independent approach to quantum gravity. The emphasis is on the basic physical principles and how one deduces predictions from them, at a level suitable for physicists in other areas such as string theor ..."
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Cited by 566 (11 self)
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We describe the basic assumptions and key results of loop quantum gravity, which is a background independent approach to quantum gravity. The emphasis is on the basic physical principles and how one deduces predictions from them, at a level suitable for physicists in other areas such as string theory, cosmology, particle physics, astrophysics and condensed matter physics. No details are given, but references are provided to guide the interested reader to the literature. The present state of knowledge is summarized in a list of 35 key results on topics including the hamiltonian and path integral quantizations, coupling to matter, extensions to supergravity and higher dimensional theories, as well as applications to black holes, cosmology and Plank scale phenomenology. We describe the near term prospects for observational tests of quantum theories of gravity and the expectations that loop quantum gravity may provide predictions for their outcomes. Finally, we provide answers to frequently asked questions and a list of key open problems.
Antide Sitter Space, Thermal Phase Transition, and Confinement in Gauge Theories
 Adv. Theor. Math. Phys
, 1998
"... The correspondence between supergravity (and string theory) on AdS space and boundary conformal field theory relates the thermodynamics of N = 4 super YangMills theory in four dimensions to the thermodynamics of Schwarzschild black holes in Antide Sitter space. In this description, quantum phenome ..."
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Cited by 1087 (4 self)
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The correspondence between supergravity (and string theory) on AdS space and boundary conformal field theory relates the thermodynamics of N = 4 super YangMills theory in four dimensions to the thermodynamics of Schwarzschild black holes in Antide Sitter space. In this description, quantum phenomena such as the spontaneous breaking of the center of the gauge group, magnetic confinement, and the mass gap are coded in classical geometry. The correspondence makes it manifest that the entropy of a very large AdS Schwarzschild black hole must scale “holographically ” with the volume of its horizon. By similar methods, one can also make a speculative proposal for the description of large N gauge theories in four dimensions without supersymmetry. March
Results 1  10
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