US-Mexico Border: Building a Smarter Wall through Strategic Security Measure Allocation

We offer a quantitative construct for optimizing security measure investments, to achieve the most costeffective deterrence and detection capabilities for the U.S. Customs and Border Patrol (CBP). We constructed a large-scale multiple-objective portfolio optimization integer program that rapidly returns good Pareto optimal results. The model incorporates the utility of each measure and the probability of success, along with multiple other objectives. To the best of our knowledge, our work presents the first mathematical model that optimizes security strategies for the CBP and is the first to introduce a utility factor to emphasize deterrence and detection impact. The model accommodates different resources, constraints, and various types of objectives. The solution methodologies being put in place are complex, current state-of-the-art, and very effective

The fifa world cup 2002: The effects of terrorism on sport tourists

This paper discusses the relationship between sport and tourism in reference to a specific hallmark event, the Fédération Internationale de Football Association (FIFA) 2002 Football World Cup. In particular, it investigates the terrorism-related issues that affected the event and the possible implications for future mega sporting events in Australia. It seeks to contribute to awareness of spectator experiences of this event by understanding perceptions of safety and responses to security measures. A questionnaire survey of a convenience-based sample of World Cup spectators in the Republic of Korea was undertaken to determine: the extent to which the terrorist attacks on the United States of America on 11 September, 2001 changed these sport tourists’ motivations to attend the event; how safe they felt in Korea during the World Cup; and how risk management measures taken by the event organizers impacted on the tourists’ level of enjoyment. The findings are discussed in the context of sport event management, concluding with consequences for the future organization of sports events. While this study focused on the impact of an act of terrorism, it is suggested that the implications of other critical incidences with global ramifications, such as the recent war in Iraq and the outbreak of Severe Acute Respiratory Syndrome (SARS) need to be taken into account when planning mega sporting events. © 2003 Taylor & Francis Ltd

Asymmetry of localised states in a single quantum ring: polarization dependence of excitons and biexcitons

We performed spectroscopic studies of a single GaAs quantum ring with an anisotropy in the rim height. The presence of an asymmetric localised state was suggested by the adiabatic potential. The asymmetry was investigated in terms of the polarization dependence of excitons and biexcitons, where a large energy di erence (0.8 meV) in the exciton emission energy for perpendicular polarizations was observed and the oscillator strengths were also compared using the photoluminescence decay rate. For perpendicular polarizations the biexciton exhibits twice the energy di erence seen for the exciton, a fact that may be attributed to a possible change in the selection rules for the lowered symmetry.Comment: accepted in Applied physics Letter

Excited exciton and biexciton localised states in a single quantum ring

We observe excited exciton and biexciton states of localised excitons in an anisotropic quantum ring, where large polarisation asymmetry supports the presence of a crescent-like localised structure. We also find that saturation of the localised ground state exciton with increasing excitation can be attributed to relatively fast dissociation of biexcitons (? 430 ps) compared to slow relaxation from the excited state to the ground state (? 1000 ps). As no significant excitonic Aharonov-Bohm oscillations occur up to 14 T, we conclude that phase coherence around the rim is inhibited as a consequence of height anisotropy in the quantum ring.Comment: 4 pages, 4 figure

A long hard look at MCG-6-30-15 with XMM-Newton and BeppoSAX

We summarise the primary results from a 320 ks observation of the bright Seyfert 1 galaxy MCG-6-30-15 with XMM-Newton and Beppo-SAX.Comment: 4 pages, 6 figures. Proc. of the meeting: "The Restless High-Energy Universe" (Amsterdam, The Netherlands), E.P.J. van den Heuvel, J.J.M. in 't Zand, and R.A.M.J. Wijers Ed

Evolution of the electronic excitation spectrum with strongly diminishing hole-density in superconducting Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta}

A complete knowledge of its excitation spectrum could greatly benefit efforts to understand the unusual form of superconductivity occurring in the lightly hole-doped copper-oxides. Here we use tunnelling spectroscopy to measure the T\to 0 spectrum of electronic excitations N(E) over a wide range of hole-density p in superconducting Bi_{2}Sr_{2}CaCu_{2}O_{8+/delta}. We introduce a parameterization for N(E) based upon an anisotropic energy-gap /Delta (\vec k)=/Delta_{1}(Cos(k_{x})-Cos(k_{y}))/2 plus an effective scattering rate which varies linearly with energy /Gamma_{2}(E) . We demonstrate that this form of N(E) allows successful fitting of differential tunnelling conductance spectra throughout much of the Bi_{2}Sr_{2}CaCu_{2}O_{8+/delta} phase diagram. The resulting average /Delta_{1} values rise with falling p along the familiar trajectory of excitations to the 'pseudogap' energy, while the key scattering rate /Gamma_{2}^{*}=/Gamma_{2}(E=/Delta_{1}) increases from below ~1meV to a value approaching 25meV as the system is underdoped from p~16% to p<10%. Thus, a single, particle-hole symmetric, anisotropic energy-gap, in combination with a strongly energy and doping dependent effective scattering rate, can describe the spectra without recourse to another ordered state. Nevertheless we also observe two distinct and diverging energy scales in the system: the energy-gap maximum /Delta_{1} and a lower energy scale /Delta_{0} separating the spatially homogeneous and heterogeneous electronic structures.Comment: High resolution version available at: http://people.ccmr.cornell.edu/~jcdavis/files/Alldredge-condmat08010087-highres.pd

Strings between branes

D-brane configurations containing fundamental strings are constructed as classical solutions of Yang-Mills theory. The fundamental strings in these systems stretch between D-branes. In the case of D1-branes, this construction gives smooth (classical) resolutions of string junctions and string networks. Using a non-abelian Yang-Mills analysis of the string current, the string charge density is computed and is shown to have support in the region between the D-brane world-volumes. The 't Hooft-Polyakov monopole is analyzed using similar methods, and is shown to contain D-strings whose flux has support off the D-brane world-volume defined by the Higgs scalar field, when this field is interpreted in terms of a transverse dimension. The constructions presented here are used to give a qualitative picture of tachyon condensation in the Yang-Mills limit, where fundamental strings and lower-dimensional D-branes arise in a volume of space-time where brane-antibrane annihilation has occurred.Comment: 35 pages, 16 eps figures, JHEP style; v2: a comment adde

Kaluza-Klein Holography

We construct a holographic map between asymptotically AdS_5 x S^5 solutions of 10d supergravity and vacuum expectation values of gauge invariant operators of the dual QFT. The ingredients that enter in the construction are (i) gauge invariant variables so that the KK reduction is independent of any choice of gauge fixing; (ii) the non-linear KK reduction map from 10 to 5 dimensions (constructed perturbatively in the number of fields); (iii) application of holographic renormalization. A non-trivial role in the last step is played by extremal couplings. This map allows one to reliably compute vevs of operators dual to any KK fields. As an application we consider a Coulomb branch solution and compute the first two non-trivial vevs, involving operators of dimension 2 and 4, and reproduce the field theory result, in agreement with non-renormalization theorems. This constitutes the first quantitative test of the gravity/gauge theory duality away from the conformal point involving a vev of an operator dual to a KK field (which is not one of the gauged supergravity fields).Comment: 47 pages, v2: minor improvements, version to appear in JHE