Economic modelling using constraint logic programming

This paper investigates the use of constraint logic programming (CLP) in economic modelling through the design and implementation of two economic models. The first model, the Desai- Henry model contains only linear equations while the second model, constructed by the author, contains non-linear elements. In order to implement the second model, a non-linear constraint solver was constructed. This was necessary because, although CLP is a very powerful programming paradigm, currently available implementations lack any on-linear constraint solving mechanisms

Moduli spaces of torsion sheaves on K3 surfaces and derived equivalences

We show that for many moduli spaces M of torsion sheaves on K3 surfaces S, the functor D(S) -> D(M) induced by the universal sheaf is a P-functor, hence can be used to construct an autoequivalence of D(M), and that this autoequivalence can be factored into geometrically meaningful equivalences associated to abelian fibrations and Mukai flops. Along the way we produce a derived equivalence between two compact hyperkaehler 2g-folds that are not birational, for every g >= 2. We also speculate about an approach to showing that birational moduli spaces of sheaves on K3 surfaces are derived-equivalent.Comment: 28 pages. typos corrected. final version to appear in JLM

SU(2|2) for Theories with Sixteen Supercharges at Weak and Strong Coupling

We consider the dimensional reductions of N=4 Supersymmetric Yang-Mills theory on R x S^3 to the three-dimensional theory on R x S^2, the orbifolded theory on R x S^3/Z_k, and the plane-wave matrix model. With explicit emphasis on the three-dimensional theory, we demonstrate the realization of the SU(2|3) algebra in a radial Hamiltonian framework. Using this structure we constrain the form of the spin chains, their S-matrices, and the corresponding one- and two-loop Hamiltonian of the three dimensional theory and find putative signs of integrability up to the two-loop order. The string duals of these theories admit the IIA plane-wave geometry as their Penrose limit. Using known results for strings quantized on this background, we explicitly construct the strong-coupling dual extended SU(2|2) algebra and discuss its implications for the gauge theories.Comment: 37 pages, 1 figure. v2 some minor improvements to the text, version to appear in Phys.Rev.

NASA/JPL Aircraft SAR Workshop Proceedings

Speaker-supplied summaries of the talks given at the NASA/JPL Aircraft SAR Workshop on February 4 and 5, 1985, are provided. These talks dealt mostly with composite quadpolarization imagery from a geologic or ecologic prespective. An overview and summary of the system characteristics of the L-band synthetic aperture radar (SAR) flown on the NASA CV-990 aircraft are included as supplementary information. Other topics ranging from phase imagery and interferometric techniques classifications of specific areas, and the potentials and limitations of SAR imagery in various applications are discussed

Cramming: The Effects of School Accountability on College-Bound Students

This paper is the first to explore the effects of school accountability systems on high-achieving students' long-term performance. Using exceptional data from a large highly-selective state university, we relate school accountability pressure in high school to a student's university-level grades and study habits. We exploit a change in the state's accountability system in 1999 that led to some schools becoming newlythreatened by accountability pressure and others becoming newly-unthreatened to identify the effects of accountability pressure. We find that an accountability system based on a low-level test of basic skills apparently led to generally reduced performance by high-achieving students, while an accountability system based on a more challenging criterion-referenced exam apparently led to improved performance in college on mathematics and other technical subjects. Both types of systems are associated with increased "cramming" by students in college. The results indicate that the nature of an accountability system can influence its effectiveness.

Display, interpellation and interpretation: on the development of an artistic gossip practice, in the context of audience interactivity with Nottingham's lace heritage

This thesis raises concerns about current heritage practice regarding notions of inclusivity, the agency of audiences and the authority of heritage institutions, such as museums. Experts including Tony Bennet (1998), Graham Black (2005), and Eileen Hooper-Greenhill (1994) claim that recent developments in heritage practice have directed museums towards offering experiences that invite active, participatory viewing, rather than that which is passive, or merely receptive. Similarly, in the field of contemporary art practice Grant Kester and Claire Bishop argue the importance of audiences’ participation, inclusivity and agency to current approaches. Evidently, certain standpoints within the literature concerned with each of these fields, state an attitude of sensitivity to imbalances of power between audiences and either artistic or heritage practices. However, this thesis recognizes and demonstrates that authoritative, or hierarchical approaches to audiences exist within each field, and guided by poststructurally informed theoretical perspectives, it confronts these approaches. Moreover, this thesis claims to establish a unique, interactive and practical autoethnographic approach to artistic research, which supported by its theoretical perspectives, generates non-authoritative and democratic methods. In particular, this thesis establishes that, dialogical engagement prompted by audiences’ responses to artistic situations and aesthetic objects, results in non-authoritative, or democratic encounters with heritage and contemporary art

Space station propulsion analysis study

This paper summarizes the impacts on the weight, volume and power usage of a manned space station and its 90-day resupply for three integrated, auxiliary propulsion subsystems. The study was performed in coordination with activities of the Space Staton Concept Development Group (CDG). The study focused on three space station propulsion high-low thrust options that make use of fluids that will be available on the manned space station. Specific uses of carbon dioxide, water and cryogen boiloff were considered. For each of the options the increase in station hardware mass and volume to accommodate the dual thrust option is offset by the resupply savings, relative to the reference hydrazine system, after one to several resupplies. Over the life of the station the savings in cost of logistics could be substantial. The three options are examples of alternative technology paths that, because of the opportunity they provide for integration with the environmental control life support system (ECLSS) and OTV propellant storage systems, may reduce the scarring which is required on the early station to meet the increasing propulsion requirements of the growth station