343 research outputs found

    Endoscopy in Renal Cancer Organ Preservation Treatments

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    This chapter traces the shift in treatment of localised renal cancer from major open surgery to endoscopic (ie laparoscopy) techniques. It also details the shift in treatment intent for localised Renal cancer toward Organ preservation. With advancement in technology and experience, the principles of endoscopic surgery have been adapted to treat renal malignancy with minimum complications and with maximal preservation of Renal function so much so that endoscopic techniques are seen as the “gold standard” by many. The chapter details these minimally invasive techniques of laparoscopic and Robotic partial nephrectomy and compares and contrasts both Oncological and Functional outcomes from both

    Hyperbolic Space Cosmologies

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    We present a systematic study of accelerating cosmologies obtained from M/string theory compactifications of hyperbolic spaces with time-varying volume. A set of vacuum solutions where the internal space is a product of hyperbolic manifolds is found to give qualitatively the same accelerating four-dimensional FLRW universe behavior as a single hyperbolic space. We also examine the possibility that our universe is a hyperbolic space and provide exact Milne type solutions, as well as intersecting S-brane solutions. When both the usual 4D spacetime and the m-dimensional internal space are hyperbolic, we find eternally accelerating cosmologies for m7m\geq 7, with and without form field backgrounds. In particular, the effective potential for a magnetic field background in the large 3 dimensions is positive definite with a local minimum and thus enhances the eternally accelerating expansion.Comment: 33 pages, 2 figures; v2 refs added; v3 minor change in text, JHEP versio

    Precision Electroweak Observables in the Minimal Moose Little Higgs Model

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    Little Higgs theories, in which the Higgs particle is realized as the pseudo-Goldstone boson of an approximate global chiral symmetry have generated much interest as possible alternatives to weak scale supersymmetry. In this paper we analyze precision electroweak observables in the Minimal Moose model and find that in order to be consistent with current experimental bounds, the gauge structure of this theory needs to be modified. We then look for viable regions of parameter space in the modified theory by calculating the various contributions to the S and T parameters.Comment: v2: 17 pages, 9 figures. Typeset in JHEP style. Added a references and two figures showing parameter space for each of two reference points. Corrected typo

    Constant magnetic field in closed string theory: an exactly solvable model

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    We consider a simple model describing a closed bosonic string in a constant magnetic field. Exact conformal invariance demands also the presence of a non-trivial metric and antisymmetric tensor (induced by the magnetic field). The model is invariant under target space duality in a compact Kaluza-Klein direction introduced to couple the magnetic field. Like open string theory in a constant gauge field, or closed string theory on a torus, this model can be straightforwardly quantized and solved with its spectrum of states and partition function explicitly computed. Above some critical value of the magnetic field an infinite number of states become tachyonic, suggesting a presence of phase transition. We also construct heterotic string generalisations of this bosonic model in which the constant magnetic field is embedded either in the Kaluza-Klein or internal gauge group sector.Comment: 39 pages, harvmac (some corrections and addenda; version to appear in Nuclear Physics

    Sub-wavelength lithography over extended areas

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    We demonstrate a systematic approach to sub-wavelength resolution lithographic image formation on films covering areas larger than a wavelength squared. For example, it is possible to make a lithographic pattern with a feature size resolution of λ/[2(N+1)]\lambda/[2(N+1)] by using a particular 2M2 M-photon, multi-mode entangled state, where N<MN < M, and banks of birefringent plates. By preparing a statistically mixed such a state one can form any pixel pattern on a (N+1)2MN×(N+1)2MN(N+1) 2^{M-N} \times (N+1) 2^{M-N} pixel grid occupying a square with a side of L=2MN1L=2^{M-N-1} wavelengths. Hence, there is a trade-off between the exposed area, the minimum lithographic feature size resolution, and the number of photons used for the exposure. We also show that the proposed method will work even under non-ideal conditions, albeit with somewhat poorer performance.Comment: 8 pages, 8 figures, 1 table. Written in RevTe

    Localized Intersections of Non-Extremal p-branes and S-branes

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    A class of solutions to Supergravity in 10 or 11 dimensions is presented which extends the non-standard or semi-local intersections of Dp-branes to the case of non-extremal p-branes. The type of non-extremal solutions involved in the intersection is free and we provide two examples involving black-branes and/or D-\bar{D} systems. After a rotation among the time coordinate and a relatively transverse radial direction the solutions admit the interpretation of an intersection among D-branes and S-branes. We speculate on the relevance of these configurations both to study time dependent phenomena in the AdS/CFT correspondence as well as to construct cosmological brane-world scenarios within String Theory admitting accelerating expansion of the Universe.Comment: 31 pages, latex file; v2: typos corrected and references adde

    Development of a Keetch and Byram based drought index sensitive to forest management in Mediterranean conditions

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    [EN] The present work aims to take a closer look at the behavior of two releases of the Keetch Byram droughtindex (KBDI) under different forest management strategies in Mediterranean conditions. Since theseversions of the index were demonstrated to be insensitive to the changes in water balance caused bydifferent thinning treatments, a new KBDI-based index sensitive to silviculture operations was developed.This new approach enabled us to simulate the benefits achieved from a thinning operation in terms offorest fire risk reduction. Abatements of 22.5% and 26.4% in KBDI were obtained for the 2009 and 2010high-risk forest fire periods, respectively, due to thinning. The reductions observed in the short-term didnot disappear in a long term. A plot thinned 10 years ago showed KBDI reductions of 12.5% and 6.7% withrespect to a non-managed plot (control treatment) in the same period. Finally, in order to make possibleapplication of the new index to other stands, coefficients of the index were based on well-known andeasy to get tree-related and physiological variables.This study is part of the research project: "CGL2011-28776-C02-02, Hydrological characterization of forest structures at plot scale for an adaptive management, Hydrosil", funded by the Spanish Ministry of Science and Innovation and FEDER funds.García Prats, A.; Campo García, ADD.; Tarcisio Fernandes, JG.; Molina Herrera, A. (2015). Development of a Keetch and Byram based drought index sensitive to forest management in Mediterranean conditions. Agricultural and Forest Meteorology. (205):40-50. https://doi.org/10.1016/j.agrformet.2015.02.009S405020

    Electromagnetic Strings: Complementarity between Time and Temperature

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    We investigate some of the intricate features in a gravity decoupling limit of a open bosonic string theory, in a constant electromagnetic (EM-) field. We explain the subtle nature of space-time at short distances, due to its entanglement with the gauge field windings in the theory. Incorporating the mass-shell condition in the theory, we show that the time coordinate is small, of the order of EM-string scale, and the space coordinates are large. We perform a careful analysis in the critical regime to describe the decoupling of a series of gauge-string windings in successions, just below the Hagedorn temperature. We argue for the condensation of gauge-string at the Hagedorn temperature, which is followed by the decoupling of tachyonic particles. We demonstrate the phenomena by revoking the effective noncommutative dynamics for the D(3)-brane and obtain nonlinear corrections to U(1) gauge theory. We discuss the spontaneous breaking of noncommutative U(1) symmetry and show that the Hagedorn phase is described by the noninteracting gauge particles. The notion of time reappears in the phase at the expense of temperature. It suggests a complementarity between two distinct notions, time and temperature, at short distances.Comment: 32 pages, 2 figures, renamed title, added clarification on winding modes, corrected typos, added reference
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