9,457 research outputs found
Federal Terrorism Risk Insurance
The terrorist attacks of September 11, 2001 represented a loss for commercial property & casualty insurers that was both unprecedented and unanticipated. After sustaining this record capital loss, the availability of adequate private insurance coverage against future terrorist attacks came into question. Concern over the potential adverse consequences of the lack of availability of insurance against terrorist incidents led to calls for federal intervention in insurance markets. This paper discusses the economic rationale for and against federal intervention in the market, and concludes that the benefits from establishing a temporary transition program, during which the private sector can build capacity and adapt to a dramatically changed environment for terrorism risk, may provide benefits to the economy that exceed the direct and indirect costs.
SMP: A solid modeling program
A prototype solid modeling program, SMP, developed by CSC for Langley Research Center (LaRC) is documented in this paper. The SMP software is employed by the System and Experiments Branch (SEB) of the Space Systems Division (SSD) for preliminary space station design, but is intended as a general purpose tool. The SMP document provides details concerning: the basic geometric modeling primitives and associated operators, the data representation scheme utilized to structure the geometric model, the available commands for both editing and displaying the solid model, the interactive user interface and the input/output interfaces to external software, and the utility of the package in the LaRC computing environment. The document is sufficiently detailed to serve both as a user's guide and reference manual
Spectrum of TeV Particles in Warped Supersymmetric Grand Unification
In warped supersymmetric grand unification, XY gauge particles appear near
the TeV scale along with Kaluza-Klein towers of the standard model gauge
fields. In spite of this exotic low-energy physics, MSSM gauge coupling
unification is preserved and proton decay is naturally suppressed. In this
paper we study in detail the low-lying mass spectrum of superparticles and GUT
particles in this theory, taking supersymmetry breaking to be localized to the
TeV brane. The masses of the MSSM particles, Kaluza-Klein modes, and XY states
are all determined by two parameters, one which fixes the strength of the
supersymmetry breaking and the other which sets the scale of the infrared
brane. A particularly interesting result is that for relatively strong
supersymmetry breaking, the XY gauginos and the lowest Kaluza-Klein excitations
of the MSSM gauginos may both lie within reach of the LHC, providing the
possibility that the underlying unified gauge symmetry and the enhanced N=2
supersymmetry of the theory will both be revealed.Comment: 29 pages, 5 figure
Gauge Theories in and Fine-Lattice Deconstruction
The logarithmic energy dependence of gauge couplings in AdS_5 emerges almost
automatically when the theory is deconstructed on a coarse lattice. Here we
study the theory away from the coarse-lattice limit. While we cannot
analytically calculate individual KK masses for a fine lattice, we can
calculate the product of all non-zero masses. This allows us to write down the
gauge coupling at low energies for any lattice-spacing and curvature. As
expected, the leading log behaviour is corrected by power-law contributions,
suppressed by the curvature. We then turn to intermediate energies, and discuss
the gauge coupling and the gauge boson profile in perturbation theory around
the coarse-lattice limit.Comment: 17 pages, 1 figure, typos in listing version of abstract correcte
Anti-pheromone as a tool for better exploration of search space
Many animals use chemical substances known as pheromones to induce behavioural changes in other members of the same species. The use of pheromones by ants in particular has lead to the development of a number of computational analogues of ant colony behaviour including Ant Colony Optimisation. Although many animals use a range of pheromones in their communication, ant algorithms have typically focused on the use of just one, a substance that encourages succeeding generations of (artificial) ants to follow the same path as previous generations. Ant algorithms for multi-objective optimisation and those employing multiple colonies have made use of more than one pheromone, but the interactions between these different pheromones are largely simple extensions of single criterion, single colony ant algorithms. This paper investigates an alternative form of interaction between normal pheromone and anti-pheromone. Three variations of Ant Colony System that apply the anti-pheromone concept in different ways are described and tested against benchmark travelling salesman problems. The results indicate that the use of anti-pheromone can lead to improved performance. However, if anti-pheromone is allowed too great an influence on ants' decisions, poorer performance may result
Unification and the Hierarchy from AdS5
In AdS5, the coupling for bulk gauge bosons runs logarithmically, not as a
power law. For this reason, one can preserve perturbative unification of
couplings. Depending on the cutoff, this can occur at a high scale. We discuss
subtleties in the calculation and present a regularization scheme motivated by
the holographic correspondence. We find that generically, as in the standard
model, the couplings almost unify. For specific choices of the cutoff and
number of scalar multiplets, there is good agreement between the measured
couplings and the assumption of high scale unification.Comment: 5 pages, 2 figure
Computer generated animation and movie production at LARC: A case study
The process of producing computer generated 16mm movies using the MOVIE.BYU software package developed by Brigham Young University and the currently available hardware technology at the Langley Research Center is described. A general overview relates the procedures to a specific application. Details are provided which describe the data used, preparation of a storyboard, key frame generation, the actual animation, title generation, filming, and processing/developing the final product. Problems encountered in each of these areas are identified. Both hardware and software problems are discussed along with proposed solutions and recommendations
SMP: A solid modeling program version 2.0
The Solid Modeling Program (SMP) provides the capability to model complex solid objects through the composition of primitive geometric entities. In addition to the construction of solid models, SMP has extensive facilities for model editing, display, and analysis. The geometric model produced by the software system can be output in a format compatible with existing analysis programs such as PATRAN-G. The present version of the SMP software supports six primitives: boxes, cones, spheres, paraboloids, tori, and trusses. The details for creating each of the major primitive types is presented. The analysis capabilities of SMP, including interfaces to existing analysis programs, are discussed
Sequestering CP Violation and GIM-Violation with Warped Extra Dimensions
We propose a model of spontaneous CP violation to address the strong CP
problem in warped extra dimensions that relies on sequestering flavor and CP
violation. We assume that brane-localized Higgs Yukawa interactions respect a
U(3) flavor symmetry that is broken only by bulk fermion mass and Yukawa terms.
All CP violation arises from the vev of a CP-odd scalar field localized in the
bulk. To suppress radiative corrections to theta-bar, the doublet quarks in
this model are localized on the IR brane. We calculate constraints from
flavor-changing neutral currents (FCNCs), precision electroweak measurements,
CKM unitarity, and the electric dipole moments in this model and predict
theta-bar to be at least about 10^-12.Comment: 38 page
Deconstruction and Gauge Theories in AdS_5
On a slice of AdS_5, despite having a dimensionful coupling, gauge theories
can exhibit logarithmic dependence on scale. In this paper, we utilize
deconstruction to analyze the scaling behavior of the theory, both above and
below the AdS curvature scale, and shed light on position-dependent
regularizations of the theory. We comment on applications to geometries other
than AdS.Comment: 15 pages, 1 figur
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