New Phases of Near-Extremal Branes on a Circle

We study the phases of near-extremal branes on a circle, by which we mean near-extremal branes of string theory and M-theory with a circle in their transverse space. We find a map that takes any static and neutral Kaluza-Klein black hole, i.e. any static and neutral black hole on Minkowski-space times a circle M^d x S^1, and map it to a corresponding solution for a near-extremal brane on a circle. The map is derived using first a combined boost and U-duality transformation on the Kaluza-Klein black hole, transforming it to a solution for a non-extremal brane on a circle. The resulting solution for a near-extremal brane on a circle is then obtained by taking a certain near-extremal limit. As a consequence of the map, we can transform the neutral non-uniform black string branch into a new non-uniform phase of near-extremal branes on a circle. Furthermore, we use recently obtained analytical results on small black holes in Minkowski-space times a circle to get new information about the localized phase of near-extremal branes on a circle. This gives in turn predictions for the thermal behavior of the non-gravitational theories dual to these near-extremal branes. In particular, we give predictions for the thermodynamics of supersymmetric Yang-Mills theories on a circle, and we find a new stable phase of (2,0) Little String Theory in the canonical ensemble for temperatures above its Hagedorn temperature.Comment: 72 pages, 5 figures. v2: Typos fixed, refs. added. v3: Sec. 3.2 fixe

Sensitivity to measurement perturbation of single atom dynamics in cavity QED

We consider continuous observation of the nonlinear dynamics of single atom trapped in an optical cavity by a standing wave with intensity modulation. The motion of the atom changes the phase of the field which is then monitored by homodyne detection of the output field. We show that the conditional Hilbert space dynamics of this system, subject to measurement induced perturbations, depends strongly on whether the corresponding classical dynamics is regular or chaotic. If the classical dynamics is chaotic the distribution of conditional Hilbert space vectors corresponding to different observation records tends to be orthogonal. This is a characteristic feature of hypersensitivity to perturbation for quantum chaotic systems.Comment: 11 pages, 6 figure

Cosmological Evolution of Brane World Moduli

We study cosmological consequences of non-constant brane world moduli in five dimensional brane world models with bulk scalars and two boundary branes. We focus on the case where the brane tension is an exponential function of the bulk scalar field, $U_b \propto \exp{(\alpha \phi)}$. In the limit $\alpha \to 0$, the model reduces to the two-brane model of Randall-Sundrum, whereas larger values of $\alpha$ allow for a less warped bulk geometry. Using the moduli space approximation, we derive the four-dimensional low-energy effective action from a supergravity-inspired five-dimensional theory. For arbitrary values of $\alpha$, the resulting theory has the form of a bi-scalar-tensor theory. We show that, in order to be consistent with local gravitational observations, $\alpha$ has to be small (less than $10^{-2}$) and the separation of the branes must be large. We study the cosmological evolution of the interbrane distance and the bulk scalar field for different matter contents on each branes. Our findings indicate that attractor solutions exist which drive the moduli fields towards values consistent with observations. The efficiency of the attractor mechanism crucially depends on the matter content on each branes. In the five-dimensional description, the attractors correspond to the motion of the negative tension brane towards a bulk singularity, which signals the eventual breakdown of the four-dimensional description and the necessity of a better understanding of the bulk singularity.Comment: 18 pages, 10 figures, typos and factor of 2 corrected, version to appear in Physical Review

Brane World Dynamics and Conformal Bulk Fields

In the Randall-Sundrum scenario we investigate the dynamics of a spherically symmetric 3-brane world when matter fields are present in the bulk. To analyze the 5-dimensional Einstein equations we employ a global conformal transformation whose factor characterizes the $Z_2$ symmetric warp. We find a new set of exact dynamical collapse solutions which localize gravity in the vicinity of the brane for a stress-energy tensor of conformal weight -4 and a warp factor that depends only on the coordinate of the fifth dimension. Geometries which describe the dynamics of inhomogeneous dust and generalized dark radiation on the brane are shown to belong to this set. The conditions for singular or globally regular behavior and the static marginally bound limits are discussed for these examples. Also explicitly demonstrated is complete consistency with the effective point of view of a 4-dimensional observer who is confined to the brane and makes the same assumptions about the bulk degrees of freedom.Comment: 26 pages, latex, no figures. Minor revisions. Some references added. Revised version to appear in Phys. Rev.

Detector Description and Performance for the First Coincidence Observations between LIGO and GEO

For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial change

Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo

We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole (PBH) binary coalescence with component masses in the range 0.2--$1.0 M_\odot$. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing non-spinning black holes with masses in the range 0.2--$1.0 M_\odot$, we place an observational upper limit on the rate of PBH coalescence of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.

Dark Radiation Dynamics on the Brane

We investigate the dynamics of a spherically symmetric vaccum on a Randall and Sundrum 3-brane world. Under certain natural conditions, the effective Einstein equations on the brane form a closed system for spherically symmetric dark radiation. We determine exact dynamical and inhomogeneous solutions, which are shown to depend on the brane cosmological constant, on the dark radiation tidal charge and on its initial energy configuration. We identify the conditions defining these solutions as singular or as globally regular. Finally, we discuss the confinement of gravity to the vicinity of the brane and show that a phase transition to a regime where gravity is not bound to the brane may occur at short distances during the collapse of positive dark energy density on a realistic de Sitter brane.Comment: 26 pages, LaTeX, 11 EPS figures. Two references added with some adjustments to the text. Version to appear in Phys. Rev.

Splenectomy for splenomegaly and secondary hypersplenism

Splenomegaly and secondary hypersplenism may be associated with acute and chronic infections, autoimmune states, portal hypertension or splenic vein thrombosis, and a number of infiltrative and neoplastic conditions involving the spleen. Our experience and that of others with these various conditions demonstrates that the decision to perform splenectomy should be based on well-defined and often strictly limited indications. Except for idiopathic splenomegaly, the presence and severity of secondary hypersplenism or severely symptomatic splenomegaly should be well documented. In each case, the potential for palliation and known mean duration of expected response must be weighed against the increased morbidity and mortality of splenectomy (as compared to operation for “primary” hypersplenism) . La splénomégalie avec hypersplénisme secondaire relève de multiples causes: infection aigue ou chronique, états autoimmunologiques, hypertension portale, thrombose de la veine splénique, lésions tumorales spléniques. L'expérience de l'auteur qui rejoint celle de nombreux collègues lui permet d'affirmer que les indications de la splénectomie doivent être bien définies et sont strictement limitées. A l'exception de la splénomégalie idiopathique, l'existence et l'intensité de l'hypersplénisme, l'importance des symptomes provoqués par la splénomégalie doivent être aprréciées avec précision. Dans chaque cas le potentiel de la rémission de l'affection et la durée de la rémission doivent être pris en considération en fonction de l'éventuelle morbidité et de l'éventuelle mortalité de la splénectomie (par comparaison avec la splénectomie pour hypersplénisme primaire). Eplenomegalia e hiperesplenismo secundario pueden estar asociados con infecciones agudas y crónicas, estados autoinmunes (síndrome de Felty, lupus eritematoso sistémico), “esplenomegalia congestiva” por hipertensión portal o trombosis de la vena esplénica y con una variedad de entidades de tipo infiltrativo y neoplásico que afectan al bazo (sarcoidosis, enfermedad de Gaucher, varios desórdenes mieloproliferativos y linfomas). Nuestra experiencia, y aquella de otros autores, con tales condiciones demuestra que la decisión de realizar esplenectomía debe estar fundamentada en indicaciones bien definidas y estrictamente limitadas. Excepto en casos de esplenomegalia idiopática, la presencia y severidad del hiperesplenismo secundario o de esplenomegalia severamente sintomática debe ser bien documentada. En cada caso debe determinarse el potencial de paliación y la duración de la respuesta que se espera obtener frente a la incrementada morbilidad y mortalidad de la esplenectomía (en comparación con la operación que se realiza por hiperesplenismo “primario”).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41318/1/268_2005_Article_BF01655279.pd