Dynamical suppression of large instantons

We investigate the distribution of instanton sizes in the framework of a simplified model for ensembles of instantons. This model takes into account the non-diluteness of instantons. The infrared problem for the integration over instanton sizes is dealt with in a self-consistent manner by approximating instanton interactions by a repulsive hard core potential. This leads to a dynamical suppression of large instantons. The characteristic features of the instanton size distribution are studied by means of analytic and Monte Carlo methods. We find a power law behaviour for small sizes, consistent with the semi-classical results. At large instanton sizes the distribution decays exponentially. The results are compared with those from lattice simulations.Comment: 2 pages, 1 figure, talk presented at Lattice2001(confinement

Pricing and Hedging Guaranteed Returns on Mix Funds

Abstract\ud In this paper we propose a valuation and hedging strategy for a guaranteed minimal rate of return on a mix fund, which participates in both bonds and stocks. For the case where a fixed amount of money is invested, we show that a European put option on the mix fund replicates the cash flows of this guarantee at all times and using the arbitrage-free pricing methodology, the market value of the guarantee can be obtained explicitly. Using historical data, we show that modeling the correlation between equity and bond returns is of fundamental importance when the stochastic nature of the term structure of interest rates is taken into account. For this model we define a hedging strategy which shows how the dependency of the option on the changing yield of the bond fund can be hedged away using mix fund contracts. We also show how Monte Carlo methods can be used to analyze the case where the guarantee is given on periodically invested fixed amounts of money instead of one single payment

Two-dimensional anisotropic Heisenberg antiferromagnet in a field

The classical, square lattice, uniaxially anisotropic Heisenberg antiferromagnet in a magnetic field parallel to the easy axis is studied using Monte Carlo techniques. The model displays a long-range ordered antiferromagnetic, an algebraically ordered spin-flop, and a paramagnetic phase. The simulations indicate that a narrow disordered phase intervenes between the ordered phases down to quite low temperatures. Results are compared to previous, partially conflicting findings on related classical models as well as the quantum variant with spin S=1/2.Comment: 8 pages, 9 figure

Polytool: polynomial interpretations as a basis for termination analysis of Logic programs

Our goal is to study the feasibility of porting termination analysis techniques developed for one programming paradigm to another paradigm. In this paper, we show how to adapt termination analysis techniques based on polynomial interpretations - very well known in the context of term rewrite systems (TRSs) - to obtain new (non-transformational) ter- mination analysis techniques for definite logic programs (LPs). This leads to an approach that can be seen as a direct generalization of the traditional techniques in termination analysis of LPs, where linear norms and level mappings are used. Our extension general- izes these to arbitrary polynomials. We extend a number of standard concepts and results on termination analysis to the context of polynomial interpretations. We also propose a constraint-based approach for automatically generating polynomial interpretations that satisfy the termination conditions. Based on this approach, we implemented a new tool, called Polytool, for automatic termination analysis of LPs

Afro-Brazilian Pentecostal re-formations of relationships across two generations of Mozambican women

Scholars of Pentecostalism in Africa have repeatedly shown that this religion generally attracts younger generations who perceive the Pentecostal theology of liberation from the bonds of kinship, tradition, and elders as very powerful. This article contributes to the existing scholarly field by examining how different generations of working women and female students in Mozambique find the Afro-Brazilian Pentecostal teachings and practices attractive, particularly when it comes to reshaping their relationships with kin, (ancestral) spirits, and men. It considers how Afro-Brazilian Pentecostalism is helping both younger and older women to reorder their relationships. Drawing on the concept of heterotopia, the role of age is highlighted to demonstrate that Afro-Brazilian Pentecostalism actively seeks to erase important generational hierarchies and differences, turning them into spiritual issues that affect all women regardless of age or generation. © 2012 by Koninklijke Brill N.V., Leiden, The Netherlands

Paving the path towards platform engineering using a comprehensive reference model

Amidst the growing popularity of platform engineering, promising improved productivity and enhanced developer experience through an internal developer platform (IDP), this research addresses the prevalent challenge of a lack of a shared understanding in the field and the complications in defining effective, customized strategies. Introducing a definitive Platform Engineering Reference Model (PE-RM) based on the Open Distributed Processing reference model (ODP-RM) framework to provide a common under- standing. This model offers a structured framework for software organizations to create tailored platform engineering strategies and realize the full potential of platform engineering. The reference model is val- idated by conducting a case study in which a contextual design and technical implementation guided by the reference model is proposed. The case study offers guidance in designing platform engineering in the context of a software organization. Furthermore, it showcases how to construct a technical platform engineering implementation, which includes experiments exposing the productivity improvements and applicability of the implementation. By facilitating a shared vocabulary and providing a roadmap for implementation, this research aims to mitigate prevailing complexities and accelerate the adoption and effectiveness of platform engineering across organizations