A discretized approach to W.T. Gowers' game

We give an alternative proof of W. T. Gowers' theorem on block bases by reducing it to a discrete analogue on specific countable nets. We also give a Ramsey type result on k-tuples of block sequences in a normed linear space with a Schauder basis.Comment: Revised version, 13 page

Hausdorff Measures and Functions of Bounded Quadratic Variation

To each function $f$ of bounded quadratic variation ($f\in V_2$) we associate a Hausdorff measure $\mu_f$. We show that the map $f\to\mu_f$ is locally Lipschitz and onto the positive cone of $\mathcal{M}[0,1]$. We use the measures $\{\mu_f:f\in V_2\}$ to determine the structure of the subspaces of $V_2^0$ which either contain $c_0$ or the square stopping time space $S^2$.Comment: 36 pages This is a revised version with few typos and linguistic correction

The influence of total gas content on the inception of cavitation in a small centrifugal pump

The cessation of cavitation as influenced by the total gas content of water has been studied in a small centrifugal pump. The cover of the impeller and the pump casing were constructed of perspex thus allowing optical observation. The water used was tap water. The cessation of caviation in the blades of the impeller was defined optically under stroboscopic light while the pressure in the caviation rig which originally had been brought to a suitable low level was gradually increased. Tests were carried out with the pump operating at various speeds while the flow regulating valve was kept at fixed "opening". In spite of the considerable scatter of the results an almost linear dependence exists between critical pressure for caviation and total gas content. The influence of total gas content on cessation is more pronounced for lower than for higher speeds of the pump. The results of the present study are in qualitative agreement with that of many previous investigators among whom we mention the works of Ntimachi, Crump and Shmuglyakov. Whereas a pronounced effect of total gas content was found on the critical caviation conditions, tests on various degrees of cavitation showed no noticeable effect of gas content on developed stages of cavitation. During the preparation of the small cavitation rig for the present investigation much effort was spent on the detection and elimination of leakages of air into the circuit. Among these leakages the most undesirable was that through the gland of the spindle of the pump. This was stopped by a simple device described in the text. Included in the APPENDICES to the thesis are 5 papers published by the Fluids division of M.E.R.L. with the permission of the Dean of the Faculty of Engineering. In these are included a critical survey on the various methods for total gas content measurements, the description of a new apparatus constructed and of a new method developed for accurate determination of the total gas content, the development of two new methods for sampling water for gas content measurements and an experimental study of the deaeration of the water in the cavitation rig under various rates of flow. In the thesis there are also included a short summary of recent opinions on the mechanics of cavitation inception, and a brief classification of the main studies which have been done up to now on the influence of total gas content on cavitation inception. Following the present experimental results a new expression for Thoma's cavitation parameter has been derived which includes the effect of total gas content on the inception. The calibration of the venturi meter and motor and the performance characteristics of the centrifugal pump have been included in the APPENDICES. A list of references appears at the end of the thesis

EXPAMOD: A methodological Tool for Linking Farm and Market Models by Means of Econometric Response Functions

Technical change at the farm level or changes in input prices often entail that the firm's supply function changes. These changes can take place in numerous ways. This paper presents a methodology that increases the consistency in supply responses across various sets of agricultural products and farm types with a market model based on a statistical response function approach. Since most farm simulation models are limited to a subset of regions and farm types, the linkage to an aggregated model requires a procedure for expanding these results to non sample regions, so that full regional coverage is achieved. This paper addresses theoretical aspects related to the consistency between micro and market level models. Next it deals with some empirical findings related to the selection of different functional forms for extrapolation. We conclude with a critical reflection on applicability of this method in addressing further needs on up-scaling of other economic as well as non-economic indicators.farm models, market models, extrapolation, Farm Management,

Hadron therapy information sharing prototype

The European PARTNER project developed a prototypical system for sharing hadron therapy data. This system allows doctors and patients to record and report treatment-related events during and after hadron therapy. It presents doctors and statisticians with an integrated view of adverse events across institutions, using open-source components for data federation, semantics, and analysis. There is a particular emphasis upon semantic consistency, achieved through intelligent, annotated form designs. The system as presented is ready for use in a clinical setting, and amenable to further customization. The essential contribution of the work reported here lies in the novel data integration and reporting methods, as well as the approach to software sustainability achieved through the use of community-supported open-source components