Open string mirror maps from Picard- Fuchs equations on relative cohomology

A method for computing the open string mirror map and superpotential for noncompact Calabi-Yaus, following the physical computations of Lerche and Mayr, is presented. It is also shown that the obvious extension of these techniques to the compact case is not consistent. As an example, the local CP^2 case is worked out in 2 ways.Comment: 29 pages; reinterpretation of compact calculations, and another def'n of noncompact relative cohomolog

On equivariant mirror symmetry for local P^2

We solve the problem of equivariant mirror symmetry for O(-3)->P^2 for the (three) cases of one independent equivariant parameter. This gives a decomposition of mirror symmetry for local P^2 into that of three subspaces, each of which may be considered independently. Finally, we give a new interpretation of mirror symmetry for O(k)+O(-2-k)->P^1.Comment: 26 pages, 4 figures. v2: minor correction in section

Extending the Picard-Fuchs system of local mirror symmetry

We propose an extended set of differential operators for local mirror symmetry. If $X$ is Calabi-Yau such that $\dim H_4(X,\Z)=0$, then we show that our operators fully describe mirror symmetry. In the process, a conjecture for intersection theory for such $X$ is uncovered. We also find new operators on several examples of type $X=K_S$ through similar techniques. In addition, open string PF systems are considered.Comment: 47 pages, 7 figures. Minor errors corrected, including the correction of the triple intersection numbers for the del Pezzo surfac

Local mirror symmetry of curves: Yukawa couplings and genus 1

We continue our study of equivariant local mirror symmetry of curves, i.e. mirror symmetry for X_k=O(k)+O(-2-k) over P^1 with torus action (lambda_1,lambda_2) on the bundle. For the antidiagonal action lambda_1=-lambda_2, we find closed formulas for the mirror map and a rational B model Yukawa coupling for all k. Moreover, we give a simple closed form for the B model genus 1 Gromov-Witten potential. For the diagonal action lambda_1=lambda_2, we argue that the mirror symmetry computation is equivalent to that of the projective bundle P(O+O(k)+O(-2-k)) over P^1. Finally, we outline the computation of equivariant Gromov-Witten invariants for A_n singularities and toric tree examples via mirror symmetry.Comment: 20 pages, no figures; v2: added details on connection to hep-th/0606120; v3: corrected triple intersection number, which gives sleek formula for Yukawa coupling

Model Selection Criteria for Segmented Time Series from a Bayesian Approach to Information Compression

The principle that the simplest model capable of describing observed phenomena should also correspond to the best description has long been a guiding rule of inference. In this paper a Bayesian approach to formally implementing this principle is employed to develop model selection criteria for detecting structural change in financial and economic time series. Model selection criteria which allow for multiple structural breaks and which seek the optimal model order and parameter choices within regimes are derived. Comparative simulations against other popular information based model selection criteria are performed. Application of the derived criteria are also made to example financial and economic time series.Complexity theory; segmentation; break points; change points; model selection; model choice.

Marine Heritage Monitoring with High Resolution Survey Tools: ScapaMAP 2001-2006

Archaeologically, marine sites can be just as significant as those on land. Until recently, however, they were not protected in the UK to the same degree, leading to degradation of sites; the difficulty of investigating such sites still makes it problematic and expensive to properly describe, schedule and monitor them. Use of conventional high-resolution survey tools in an archaeological context is changing the economic structure of such investigations however, and it is now possible to remotely but routinely monitor the state of submerged cultural artifacts. Use of such data to optimize expenditure of expensive and rare assets (e.g., divers and on-bottom dive time) is an added bonus. We present here the results of an investigation into methods for monitoring of marine heritage sites, using the remains of the Imperial German Navy (scuttled 1919) in Scapa Flow, Orkney as a case study. Using a baseline bathymetric survey in 2001 and a repeat bathymetric and volumetric survey in 2006, we illustrate the requirements for such surveys over and above normal hydrographic protocols and outline strategies for effective imaging of large wrecks. Suggested methods for manipulation of such data (including processing and visualization) are outlined, and we draw the distinction between products for scientific investigation and those for outreach and education, which have very different requirements. We then describe the use of backscatter and volumetric acoustic data in the investigation of wrecks, focusing on the extra information to be gained from them that is not evident in the traditional bathymetric DTM models or sounding point-cloud representations of data. Finally, we consider the utility of high-resolution survey as part of an integrated site management policy, with particular reference to the economics of marine heritage monitoring and preservation

Ex-Post management of public sector contracts

Public procurement policies requiring frequent tenders and defined contracts give rise to expectations of low cost quality services and present management challenges for the post tender contract. Frequent tendering undermines the principal agent relationship and contract incompleteness allows unforeseen contingencies to threaten the specified outcomes. This thesis examines seven cases of facilities management contracts in three third-level educational institutions. Using a qualitative and interpretative methodology, the study takes an inductive theory building approach to how and why managers address challenges, and develops a conceptual model of ex post management mechanisms through the lenses of agency theory, the psychological contract, and signals. It finds that the principal agent relationship is based on both written and psychological contracts, and mechanisms include incentives, information systems, and psychological contract signals. It also finds that, rather than pursuing the terms of the written contract which are frequently incomplete, the principal and agent work together towards the broader goals of the psychological contract to maintain the contract benefits. While it has the limitations of a theory building and social constructionist approach, it offers theoretic and management relevance. It extends agency theory in public contracts by highlighting the importance of information systems, and the psychological contract in the principal agent relationship by identifying the principal’s influences and the relevance of agent’s perceived obligations in deciding responses. Through understanding these ex post mechanisms, managers may address the inevitable challenges of incomplete contracts, and foster improved responses towards optimal cost and quality outcomes