Testing for Stochastic Cointegration and Evidence for Present Value Models

Using the stochastic integration/cointegration framework of Harris, McCabe and Leybourne (2002) we revisit the problem of assessing the empirical evidence for or against the present value class of models in the bond and stock markets. This framework allows for volatility in excess of that catered for by the conventional integration/cointegration paradigm by introducing nonlinear heteroscedasticity. We propose a test for stochastic cointegration against the alternative of no cointegration and a secondary test for stationary cointegration against the heteroscedastic alternative. Asymptotic distributions of these tests under their respective null hypotheses are derived and consistency under their respective alternatives is established. In contrast to conventional cointegration tests, which we show via simulation are unreliable in the presence of the kind of volatility typical of financial data, our tests are able to uncover new cointegration evidence in favour of the present value model, particularly in the bond market.

Weathering of stone-built heritage: A lens through which to read the Anthropocene

This paper discusses how the study of stone-built heritage decay is relevant in the context of the Anthropocene by raising the complex two-way interplay between stone and society. Natural and built stone heritage is an asset that is vulnerable to present and future climate change. Especially in the context of built heritage, stone can also be conceptualized as a “large scale laboratory” in which the evolution of weathering, and thus past exposure conditions, can be studied (analogous to physical landscape studies). This concept of built heritage as a ‘recorder’ of past environmental evolution is found from the very first moments of the development of Earth sciences as a formal discipline. The ideas reviewed and presented in the paper show how stone surfaces may be used to “read” background environmental changes, trends in pollution and even catastrophic events, such as fire. Stone surfaces teach us both about the past (since human interactions with stone began and they intensified through history) and about the nature of weathering. Understanding how past environmental changes have left a trace in stone allow us to use stone as a means to predict potential impacts of future change. Such understanding may be used to inform conservation management of our irreplaceable stone-built heritage assets, as well as to plan for future climate impacts on such assets.Peer reviewe

Pathfinding in Computer Games

One of the greatest challenges in the design of realistic Artificial Intelligence (AI) in computer games is agent movement. Pathfinding strategies are usually employed as the core of any AI movement system. This report will highlight pathfinding algorithms used presently in games and their shortcomings especially when dealing with real-time pathfinding. With the advances being made in other components, such as physics engines, it is AI that is impeding the next generation of computer games. This report will focus on how machine learning techniques such as Artificial Neural Networks and Genetic Algorithms can be used to enhance an agents ability to handle pathfinding in real-time

Evaporative Moisture Loss from Heterogeneous Stone: Material- Environment Interactions During Drying

The complexities of evaporation from structurally and mineralogically heterogeneous sandstone (Locharbriggs Sandstone) are investigated through a laboratory-based experiment in which a variety of environmental conditions are simulated. Data reported demonstrate the significance of material-environment interactions on the spatial and temporal variability of evaporative dynamics. Evaporation from porous stone is determined by the interplay between environmental, material and solution properties, which govern the rate and mode by which water is transmitted to, and subsequently removed from, an evaporating surface. Initially, when the stone is saturated, evaporation is characterized by high rates of moisture loss primarily controlled by external atmospheric conditions. However, as drying progresses, eventually the hydraulic continuity between the stone surface and subsurface is disrupted with recession of the drying front and a decrease in evaporation rates which become reliant on the ability of the material to transport water vapour to the block surface. Pore size distribution and connectivity, as well as other material properties, control the timing of each stage of evaporation and the nature of the transition. These experimental data highlight the complexity of evaporation, demonstrating that different regions of the same stone can exhibit varying moisture dynamics during drying and that the rate and nature of evaporative loss differs under different environmental conditions. The results identify the importance of material-environment interactions during drying and that stone micro-environmental conditions cannot be inferred from ambient data alone. These data have significance for understanding the spatial distribution of stone surface weathering-related morphologies in both the natural and built environments where mineralogical and/or structural heterogeneity creates differences in moisture flux and hence variable drying rates. Such differences may provide a clearer explanation for the initiation and subsequent development of complex weathering responses where areas of significant deterioration can be found alongside areas that exhibit little or no evidence of surface breakdown.Madrid’s Regional Government Geo-materials Programme (S2013/MIT-2914)Peer reviewe

The Pracademic and Academic in Criminal Justice Education: A Qualitative Analysis

Over the past several years, a few hundred colleagues involved in criminal justice education have participated in panel discussions and roundtables to discuss the trials and issues that have been observed by practitioners turned academics, or “pracademics.” Some complained of having difficulty breaking into academia. A debate has occurred in a number of colleges and universities over the benefit of having faculty with traditional academic credentials versus hiring non-traditional scholars with a blend of educational and practical experience. Similarly, there have been lively discussions over the appropriateness of a J.D. or professional doctorate as opposed to a Ph.D. in criminal justice. This debate started in an article in ACJS Today (2002) and continued in subsequent publications. It is believed that there is importance, benefit and relevance to incorporating practical experience on college and university campuses. In academic program after program, internships, externships, observation, and practicums have become essential in preparing students for the real world

An Experimental Examination of the Walrasian Tatonnement Mechanism

Joyce (1984) reports results of experiments of a Walrasian tatonnement auction that show that the mechanism is stable, exhibits strong convergence properties and generates efficiency averaging better than 97%. He also found that when subjects could see part of the order flow (excess demand), price tended to be lower (favorable to buyers). His experiments consisted of a stationary environment where subjects were provided with single-unit supply and demand functions. This paper assesses the robustness of his results in a more complex setting and systematically investigates the effect of various order flow information and message restriction rules on the performance of the Walrasian mechanism. In particular, our subjects were provided with multi-unit demands and supplies where equilibrium price and subject values or costs were changed each trading period

On harmonic analysis of vector-valued signals

A vector‐valued signal in N dimensions is a signal whose value at any time instant is an N‐dimensional vector, that is, an element of urn:x-wiley:mma:media:mma3938:mma3938-math-0001. The sum of an arbitrary number of such signals of the same frequency is shown to trace an ellipse in N‐dimensional space, that is, to be confined to a plane. The parameters of the ellipse (major and minor axes, represented by N‐dimensional vectors; and phase) are obtained algebraically in terms of the directions of oscillation of the constituent signals, and their phases. It is shown that the major axis of the ellipse can always be determined algebraically. That is, a vector, whose value can be computed algebraically (without decisions or comparisons of magnitude) from parameters of the constituent signals, always represents the major axis of the ellipse. The ramifications of this result for the processing and Fourier analysis of signals with vector values or samples are discussed, with reference to the definition of Fourier transforms, particularly discrete Fourier transforms, such as have been defined in several hypercomplex algebras, including Clifford algebras. The treatment in the paper, however, is entirely based on signals with values in urn:x-wiley:mma:media:mma3938:mma3938-math-0002. Although the paper is written in terms of vector signals (which are taken to include images and volumetric images), the analysis clearly also applies to a superposition of simple harmonic motions in N dimensions

On harmonic analysis of vector-valued signals

A vector‐valued signal in N dimensions is a signal whose value at any time instant is an N‐dimensional vector, that is, an element of urn:x-wiley:mma:media:mma3938:mma3938-math-0001. The sum of an arbitrary number of such signals of the same frequency is shown to trace an ellipse in N‐dimensional space, that is, to be confined to a plane. The parameters of the ellipse (major and minor axes, represented by N‐dimensional vectors; and phase) are obtained algebraically in terms of the directions of oscillation of the constituent signals, and their phases. It is shown that the major axis of the ellipse can always be determined algebraically. That is, a vector, whose value can be computed algebraically (without decisions or comparisons of magnitude) from parameters of the constituent signals, always represents the major axis of the ellipse. The ramifications of this result for the processing and Fourier analysis of signals with vector values or samples are discussed, with reference to the definition of Fourier transforms, particularly discrete Fourier transforms, such as have been defined in several hypercomplex algebras, including Clifford algebras. The treatment in the paper, however, is entirely based on signals with values in urn:x-wiley:mma:media:mma3938:mma3938-math-0002. Although the paper is written in terms of vector signals (which are taken to include images and volumetric images), the analysis clearly also applies to a superposition of simple harmonic motions in N dimensions