719 research outputs found
Wormhole phase in the RST model
We show that the RST model describing the exactly soluble black hole model
can have a dynamical wormhole solution along with an appropriate boundary
condition. The necessary exotic matter which is usually negative energy density
is remarkably produced by the quantization of the infalling matter fields. Then
the asymptotic geometry in the past is two-dimensional anti-de Sitter(AdS),
which implies the exotic matter is negative. As time goes on, the wormhole
eventually evolves into the black hole and its Hawking radiation appears. The
throat of the static RST wormhole is lower-bounded but in the presence of
infalling matter it collapses to a black hole.Comment: v1. REVTeX3, 12 pages and 1 figure; v2. JHEP3, 10 pages and 1 figure,
version published in JHE
Quantum entanglement of charges in bound states with finite-size dyons
We show that the presence of finite-size monopoles can lead to a number of
interesting physical processes involving quantum entanglement of charges.
Taking as a model the classical solution of the N=2 SU(2) Yang-Mills theory, we
study interaction between dyons and scalar particles in the adjoint and
fundamental representation. We find that there are bound states of scalars and
dyons, which, remarkably, are always an entangled configuration of the form
|\psi > =|dyon+> |scalar-> +/- |dyon->|scalar+>. We determine the energy levels
and the wave functions and also discuss their stability.Comment: 29 pages, 3 figures. Minor correction in references (to appear in
JHEP04 (2002) 010
Methodology for the damage assessment of vehicles exposed to flooding in urban areas
Within urban areas, humans carry out a great diversity of activities, and some of them require the use of vehicles. Floods, especially in urban areas, can generate significant tangible direct damages to vehicles themselves and to the urban elements in case of loss of stability and collision, which cannot be dismissed. In this paper, after a state-of-the-art review on damage curves for vehicles, a methodology to assess the direct economic impact for vehicles exposed to flooding has been described, and applied within a study carried out in the framework of the BINGO H2020 EU Project. Only three different studies focused on damages to vehicles in contact with floodwater have been found. Contrasting damage curves for vehicles are found when comparing the three approaches, however, the ones proposed by the U.S. Army Corps of Engineers (USACE) offer a high level of completeness and accuracy. Moreover, USACE''s development is the most current research and all the steps for the development of the damage curves are comprehensively described. Finally, after the description of a detailed methodology for flood damage mapping for vehicles, a procedure to evaluate the Expected Annual Damage for vehicles is offered
Representation of tropical deep convection in atmospheric models - Part 1 : Meteorology and comparison with satellite observations
Published under Creative Commons Licence 3.0. Original article can be found at : http://www.atmospheric-chemistry-and-physics.net/ "The author's copyright for this publication is transferred to University of Hertfordshire".Fast convective transport in the tropics can efficiently redistribute water vapour and pollutants up to the upper troposphere. In this study we compare tropical convection characteristics for the year 2005 in a range of atmospheric models, including numerical weather prediction (NWP) models, chemistry transport models (CTMs), and chemistry-climate models (CCMs). The model runs have been performed within the framework of the SCOUT-O3 (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere) project. The characteristics of tropical convection, such as seasonal cycle, land/sea contrast and vertical extent, are analysed using satellite observations as a benchmark for model simulations. The observational datasets used in this work comprise precipitation rates, outgoing longwave radiation, cloud-top pressure, and water vapour from a number of independent sources, including ERA-Interim analyses. Most models are generally able to reproduce the seasonal cycle and strength of precipitation for continental regions but show larger discrepancies with observations for the Maritime Continent region. The frequency distribution of high clouds from models and observations is calculated using highly temporally-resolved (up to 3-hourly) cloud top data. The percentage of clouds above 15 km varies significantly between the models. Vertical profiles of water vapour in the upper troposphere-lower stratosphere (UTLS) show large differences between the models which can only be partly attributed to temperature differences. If a convective plume reaches above the level of zero net radiative heating, which is estimated to be ~15 km in the tropics, the air detrained from it can be transported upwards by radiative heating into the lower stratosphere. In this context, we discuss the role of tropical convection as a precursor for the transport of short-lived species into the lower stratosphere.Peer reviewe
Plane wave limit of local conserved charges
We study the plane wave limit of the Backlund transformations for the
classical string in AdS space times a sphere and obtain an explicit expression
for the local conserved charges. We show that the Pohlmeyer charges become in
the plane wave limit the local integrals of motion of the free massive field.
This fixes the coefficients in the expansion of the anomalous dimension as the
sum of the Pohlmeyer charges.Comment: v2: added explanation
Quantizing three-spin string solution in AdS_5 x S^5
As was recently found in hep-th/0304255, there exists a simple
non-supersymmetric classical solution describing a closed string rotating in
S^5 and located at the center of AdS_5. It is parametrized by the angular
momentum J of the center of mass and two equal SO(6) angular momenta J' in the
two other orthogonal rotation planes. The dual N=4 SYM operators should be
scalar operators in SU(4) representations [0,J-J',2J'] or [J'-J,0,J'+J]. This
solution is stable if J' > 3/2 J and for large J + 2 J' its classical energy
admits an expansion in positive powers of g_eff = \lambda/(J + 2 J')^2: E= J +
2 J' + g_eff J' + ... . This suggests a possibility of a direct comparison with
perturbative SYM results for the corresponding anomalous dimensions in the
sector with g_eff << 1, by analogy with the BMN case. We conjecture that all
quantum sigma model string corrections are then subleading at large J', so that
the classical formula for the energy is effectively exact to all orders in
\lambda. It could then be interpolated to weak coupling, representing a
prediction for the anomalous dimensions on the SYM side. We test this
conjecture by computing the 1-loop superstring sigma model correction to the
classical energy.Comment: 25 pages, harvmac. v5: minor misprints in eqs
(2.6),(2.16),(2.20),(2.21) correcte
Rotating Strings in Confining AdS/CFT Backgrounds
We study semiclassical rotating strings in AdS/CFT backgrounds that exhibit
both confinement and finite-size effects. The energy versus spin dispersion
relation for short strings is the expected Regge trajectory behaviour, with the
same string tension as is measured by the Wilson loop. Long strings probe the
interplay between confinement and finite-size effects. In particular, the
dispersion relation for long strings shows a characteristic dependence on the
string tension and the finite-size scale.Comment: 18 pages, 3 figures. v2: minor changes, refs. adde
Developing Product Environmental Footprint Category Rules for Olive Oil
In the context of the Communication âBuilding the Single Market for Green Productsâ, the European Commission (EC) recommends a method to measure the environmental performance of products, named the Product Environmental Footprint. The PEF is a multi-criteria measure of the environmental performance of goods and services from a life cycle perspective. Currently, 25 pilot projects test the development of Product Environmental Footprint Category Rules (PEFCRs) for various products. This paper gives an overview of the process of developing the PEFCR for olive oil. An overview of the methods of the PEF screening study that aims at identifying the most relevant environmental impacts, processes and elementary flows are presented. The screening study assesses the impacts of the average olive oil consumed in the European markets.JRC.H.8-Sustainability Assessmen
Circular Semiclassical String solutions on Confining AdS/CFT Backgrounds
We study multiwrapped circular string pulsating in the radial direction of
AdS black hole. We compute the energy of this string as a function of a large
quantum number n. One then could associate it with energy and a quantum number
of states in the dual finite temperature {\cal N}=4 SYM theory as well as three
dimensional pure gauge theory. We observe that the n dependence of the energy
has a universal form. We have also considered pulsating string in the
background of the near-extremal D4-brane solution. Circular pulsating membrane
in M-theory on AdS_7\times S^4 has also been studied.Comment: 14 pages, latex, v2: typos corrected, refs. adde
Speeding Strings
There is a class of single trace operators in Yang-Mills theory
which are related by the AdS/CFT correspondence to classical string solutions.
Interesting examples of such solutions corresponding to periodic trajectories
of the Neumann system were studied recently. In our paper we study a
generalization of these solutions. We consider strings moving with large
velocities. We show that the worldsheet of the fast moving string can be
considered as a perturbation of the degenerate worldsheet, with the small
parameter being the relativistic factor . The series expansion in
this relativistic factor should correspond to the perturbative expansion in the
dual Yang-Mills theory. The operators minimizing the anomalous dimension in the
sector with given charges correspond to periodic trajectories in the mechanical
system which is closely related to the product of two Neumann systems.Comment: v3: added a reference to the earlier wor
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