13,684 research outputs found
Flow at AGS Energies: A Barometer for High Density Effects?
Preliminary data on transverse energy `flow' and event asymmetries reported
by the E877(814) collaborations are compared to ARC model calculations for
Au+Au at full AGS beam energy. ARC triple differential cross-sections for
protons and pions are presented. Proton flow is produced in ARC, with the
maximum in-plane momentum about 120 MeV/c. For central events the directed
momentum for pions is near zero, consistent with experiment. Pion momentum
opposite to the nucleons' is evident in a peripheral sample, however,
indicating that this pion `anti-flow' involves absorption by `spectator'
matter. `Squeeze-out' of protons in central events at mid-rapidity is suggested
by the ARC distributions.Comment: 8 pages REVTeX, 4 figures, (2 color included as GIF). Full postscript
figures (LARGE) available by request from: [email protected]
Correlation Functions in -Deformed N=6 Supergravity
Gauged N=8 supergravity in four dimensions is now known to admit a
deformation characterized by a real parameter lying in the interval
. We analyse the fluctuations about its anti-de Sitter
vacuum, and show that the full N=8 supersymmetry can be maintained by the
boundary conditions only for . For non-vanishing , and
requiring that there be no propagating spin s>1 fields on the boundary, we show
that N=3 is the maximum degree of supersymmetry that can be preserved by the
boundary conditions. We then construct in detail the consistent truncation of
the N=8 theory to give -deformed SO(6) gauged N=6 supergravity, again
with in the range . We show that this theory
admits fully N=6 supersymmetry-preserving boundary conditions not only for
, but also for . These two theories are related by a
U(1) electric-magnetic duality. We observe that the only three-point functions
that depend on involve the coupling of an SO(6) gauge field with the
U(1) gauge field and a scalar or pseudo-scalar field. We compute these
correlation functions and compare them with those of the undeformed N=6 theory.
We find that the correlation functions in the theory
holographically correspond to amplitudes in the U(N)_k x U(N)_{-k} ABJM model
in which the U(1) Noether current is replaced by a dynamical U(1) gauge field.
We also show that the -deformed N=6 gauged supergravities can be
obtained via consistent reductions from the eleven-dimensional or
ten-dimensional type IIA supergravities.Comment: 38 pages, one figur
Strength and Microstructure of Geopolymer Based on Fly Ash and Metakaolin
The production of Portland cement is widely regarded as a major source of greenhouse gas emissions. This contributes to 6–7% of total CO₂ emissions, according to the International Energy Agency. As a result, several efforts have been made in recent decades to limit or eliminate the usage of Portland cement in concrete. Geopolymer has garnered a lot of attention among the numerous alternatives due to its early compressive strength, low permeability, high chemical resistance, and great fire-resistant behaviour. This study looks at the strength and microstructure of geopolymer based on fly ash and a combination of metakaolin and fly ash. Compressive strengths were measured at 7, 14, and 28 days, and microstructure was examined using SEM and XRD
Thermodynamics of Dual CFTs for Kerr-AdS Black Holes
Recently Gibbons {\it et al.} in hep-th/0408217 defined a set of conserved
quantities for Kerr-AdS black holes with the maximal number of rotation
parameters in arbitrary dimension. This set of conserved quantities is defined
with respect to a frame which is non-rotating at infinity. On the other hand,
there is another set of conserved quantities for Kerr-AdS black holes, defined
by Hawking {\it et al.} in hep-th/9811056, which is measured relative to a
frame rotating at infinity. Gibbons {\it et al.} explicitly showed that the
quantities defined by them satisfy the first law of black hole thermodynamics,
while those quantities defined by Hawking {\it et al.} do not obey the first
law. In this paper we discuss thermodynamics of dual CFTs to the Kerr-AdS black
holes by mapping the bulk thermodynamic quantities to the boundary of the AdS
space. We find that thermodynamic quantities of dual CFTs satisfy the first law
of thermodynamics and Cardy-Verlinde formula only when these thermodynamic
quantities result from the set of bulk quantities given by Hawking {\it et
al.}. We discuss the implication of our results.Comment: Revtex4, twocolumn, 6 pages, v2: 7 pages, more references and
comments added, an err correcte
Considerations and design on apps for elderly with mild-to-moderate dementia
Many elderly people suffer from dementia in their daily life. The symptoms of dementia include impairments in thinking, communicating and recalling things of the past. Dementia can be caused by brain damage incurred from stroke (brain infarct), injury or other diseases. Recently, research has indicated a potential rehabilitative role for touchscreen technology in dementia. Elders can use apps to aid recall in order to support activities of daily living. Memory and activity apps can be developed for people suffering from early dementia. This paper presents the current state of development in the field of cognitive tests. It has also presented the many considerations and design issues related to the development of apps for people with dementia. © 2015 IEEE.published_or_final_versio
Development of engineering design tools to help reduce apple bruising
A large percentage of apples are wasted each year due to damage such as bruising. The apple journey from orchard to supermarket is very complex and apples are subjected to a variety of static and dynamic loads that could result in this damage occurring. The main aim of this work was to carry out numerical modelling to develop a design tool that can be used to optimise the design of harvesting and sorting equipment and packaging media to reduce the likelihood of apple bruise formation resulting from impact loads. An experimental study, along with analytical calculations, varying apple drop heights and counterface material properties, were used to provide data to validate the numerical modelling. Good correlation was seen between the models and experiments and this approach combined with previous work on static modelling should provide a comprehensive design tool for reducing the likelihood of apple bruising occurring
DC electrical distribution systems in bulidings
Author name used in this publication: Bryan PongVersion of RecordPublishe
Born-Infeld Black Holes in (A)dS Spaces
We study some exact solutions in a -dimensional Einstein-Born-Infeld
theory with a cosmological constant. These solutions are asymptotically de
Sitter or anti-de Sitter, depending on the sign of the cosmological constant.
Black hole horizon and cosmological horizon in these spacetimes can be a
positive, zero or negative constant curvature hypersurface. We discuss the
thermodynamics associated with black hole horizon and cosmological horizon. In
particular we find that for the Born-Infeld black holes with Ricci flat or
hyperbolic horizon in AdS space, they are always thermodynamically stable, and
that for the case with a positive constant curvature, there is a critical value
for the Born-Infeld parameter, above which the black hole is also always
thermodynamically stable, and below which a unstable black hole phase appears.
In addition, we show that although the Born-Infeld electrodynamics is
non-linear, both black hole horizon entropy and cosmological horizon entropy
can be expressed in terms of the Cardy-Verlinde formula. We also find a
factorized solution in the Einstein-Born-Infeld theory, which is a direct
product of two constant curvature spaces: one is a two-dimensional de Sitter or
anti-de Sitter space, the other is a ()-dimensional positive, zero or
negative constant curvature space.Comment: Latex, 18 pages with 4 eps figures, v2: Revtex, 11 pages with 4 eps
figures, to appear in PR
- …