Setting people in their environment: plant and animal remains from Anglo-Scandinavian York

INTRODUCTION: For the past millennium, the inhabitants of the centre of York have, whether hey knew it or not, been living on top of a compost heap in which are preserved all kinds of remains of Anglo-Scandinavian and early post-conquest life. The preservation of this mass of organic matter has come about because, for reasons which are not fully understood, the deposits show anoxic waterlogging - in other words they have remained moist, and decay has been inhibited by lack of free oxygen. Later citizens must often have encountered these 'peaty' deposits and wondered about some of the more recognisable biological remains, as well as the numerous artefacts, surviving in them. However, it was not until the early 20th century that the value of all this material in investigating the past started to be appreciated

Reply to Comment by Galapon on 'Almost-periodic time observables for bound quantum systems'

In a recent paper [1] (also at http://lanl.arxiv.org/abs/0803.3721), I made several critical remarks on a 'Hermitian time operator' proposed by Galapon [2] (also at http://lanl.arxiv.org/abs/quant-ph/0111061). Galapon has correctly pointed out that remarks pertaining to 'denseness' of the commutator domain are wrong [3]. However, the other remarks still apply, and it is further noted that a given quantum system can be a member of this domain only at a set of times of total measure zero.Comment: 3 page

Heart of Darkness: Modeling Public-Private Funding Interactions Inside the R&D Black Box

This paper is a first step toward closing the analytical gap in the extensive literature on the results of interactions between public and private R&D expenditures, and their joint effects on the economy. Earlier studies frequently report contradictory estimates of the response of company financed R&D to changes in the level and nature of public R&D expenditure. A major cause of "inconsistencies" in the empirical literature is the failure to recognize key differences among the various policy "experiments" being considered depending upon the economy in which they are embedded, and the type of public sector R&D spending that is contemplated. Using a simple, stylized structural model, we identify the main channels of impact of public R&D and characterize the various effects, distinguishing between short-run and long-run impacts that would show up in simple regression analyses of nominal public and private R&D expenditure variables. We offer interpretations that shed light on recent cross-section and panel data findings at both high (i.e. national) and low (specific technology area) levels of aggregation.

Heart of Darkness: Modeling Public-Private Funding Interactions Inside the R&D Black Box

This paper is a first step toward closing the analytical gap in the extensive literature on the results of interactions between public and private R&D expenditures, and their joint effects on the economy. Econometric studies in this area report a plethora of sometimes confusing and frequently contradictory estimates of the response of company financed R&D to changes in the level and nature of public R&D expenditure, but the necessary theoretical framework within which the empirical results can be interpreted is seldom provided. A major cause of inconsistencies' in the empirical literature is the failure to recognize key differences among the various policy experiments' being considered depending upon the economy in which they are embedded, and the type of public sector R&D spending that is contemplated. Using a simple, stylized structural model, we identify the main channels of impact of public R&D. We thus can characterize the various effects, distinguishing between short-run and long-run impacts that would show up in simple regression analyses of nominal public and private R&D expenditure variables. Within the context of our simple model it is possible to offer interpretations that shed light on recent cross-section and panel data findings at both high (i.e. national) and low (specific technology area) levels of aggregation.

The principle of equivalence and projective structure in space-times

This paper discusses the extent to which one can determine the space-time metric from a knowledge of a certain subset of the (unparametrised) geodesics of its Levi-Civita connection, that is, from the experimental evidence of the equivalence principle. It is shown that, if the space-time concerned is known to be vacuum, then the Levi-Civita connection is uniquely determined and its associated metric is uniquely determined up to a choice of units of measurement, by the specification of these geodesics. It is further demonstrated that if two space-times share the same unparametrised geodesics and only one is assumed vacuum then their Levi-Civita connections are again equal (and so the other metric is also a vacuum metric) and the first result above is recovered.Comment: 23 pages, submitted to Classical and Quantum Gravit