Capturing hand tremors with a fuzzy logic wheelchair joystick controller

We have designed and built a fuzzy logic wheelchair controller which minimizes the effect of Multiple Sclerosis and tremors. The aim of our project has been to give people with Multiple Sclerosis better control of an electric wheelchair by removing tremors from the joystick signal. The system intercepts the signal from the joystick and then passes it through the fuzzy logic controller. The fuzzy logic identify and eliminate erratic or unusual movements, employing a history mechanism to determine what "unusual" is. The fuzzy logic than outputs a signal which closely represents the intent of the user. This paper reports on the experiments conducted with our prototype wheelchair, using test volunteers with MS, as well as on the design of a new fuzzy controller. Also, we give a brief overview of the variety of recorded tremors. We show that those who have the most severe MS tremors benefit from the system, and are able to control the wheelchair safely

UK economic performance since 1997: growth, productivity and jobs

A common view is that the performance of the UK economy between 1997 and 2010 under Labour was very weak and that the current economic problems are a consequence of poor policies in this period. In this report, we analyse the historical performance of the UK economy since 1997 compared with other major advanced economies and with performance prior to 1997, notably the years of Conservative government, 1979-97. We focus on measures of business performance, especially productivity growth. This is a key economic indicator as in the long run, productivity determines material wellbeing - wages and consumption. Productivity determines the size of the 'economic pie' available to the citizens of a country

Understanding the Complexity of Lifted Inference and Asymmetric Weighted Model Counting

In this paper we study lifted inference for the Weighted First-Order Model Counting problem (WFOMC), which counts the assignments that satisfy a given sentence in first-order logic (FOL); it has applications in Statistical Relational Learning (SRL) and Probabilistic Databases (PDB). We present several results. First, we describe a lifted inference algorithm that generalizes prior approaches in SRL and PDB. Second, we provide a novel dichotomy result for a non-trivial fragment of FO CNF sentences, showing that for each sentence the WFOMC problem is either in PTIME or #P-hard in the size of the input domain; we prove that, in the first case our algorithm solves the WFOMC problem in PTIME, and in the second case it fails. Third, we present several properties of the algorithm. Finally, we discuss limitations of lifted inference for symmetric probabilistic databases (where the weights of ground literals depend only on the relation name, and not on the constants of the domain), and prove the impossibility of a dichotomy result for the complexity of probabilistic inference for the entire language FOL

Construction of the de Sitter supergravity

Recently, the complete action for an N=1 pure supergravity action in 4 dimensions that allows a positive, negative or zero cosmological constant has been constructed. The action is the generalization of a Volkov-Akulov action for the Goldstino coupled to supergravity. The construction uses a nilpotent multiplet. This paper is written in honour of Philippe Spindel. AVP enjoyed collaborations and many interactions with Philippe, who has always appreciated very precise derivations. We use this occasion to give a very detailed account of the calculations that lead to the published results. We review aspects of supersymmetry with de Sitter backgrounds, the treatment of auxiliary fields, and other ingredients in the construction.Comment: contribution to the proceedings of the workshop "About various kinds of interactions" in honor of Philippe Spindel; v2: changed references, and correction of torsion lagrangian (5.15

Motion in a rocked ratchet with spatially periodic friction

We present a detailed study of the transport and energetics of a Brownian particle moving in a periodic potential in the presence of an adiabatic external periodic drive. The particle is considered to move in a medium with periodic space dependent friction with the same periodicity as that of the potential but with a phase lag. We obtain several results, most of them arising due to the medium being inhomogeneous and are sensitive to the phase lag. When the potential is symmetric we show that efficiency of energy transduction can be maximised as a function of noise strength or temperature. However, in the case of asymmtertic potential the temperature may or may not facilitate the energy conversion but current reversals can be obtained as a function of temperature and the amplitude of the periodic drive. The reentrant behaviour of current can also be seen as a function of phase lag

UK Economic Performance Since 1997: Growth, Productivity and Jobs

A common view is that the performance of the UK economy between 1997 and 2010 under Labour was very weak and that the current economic problems are a consequence of poor policies in this period. In this report, we analyse the historical performance of the UK economy since 1997 compared with other major advanced economies and with performance prior to 1997, notably the years of Conservative government, 1979-97. We focus on measures of business performance, especially productivity growth. This is a key economic indicator as in the long run, productivity determines material wellbeing - wages and consumption. Productivity determines the size of the "economic pie" available to the citizens of a country.Income, productivity, UK economic performance, government economic policy, Great Recession, business