Energy-efficient adaptive wireless network design

Energy efficiency is an important issue for mobile computers since they must rely on their batteries. We present an energy-efficient highly adaptive architecture of a network interface and novel data link layer protocol for wireless networks that provides quality of service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations are necessary to achieve energy efficiency and an acceptable quality of service. The paper provides a review of ideas and techniques relevant to the design of an energy efficient adaptive wireless networ

Reconfigurable Mobile Multimedia Systems

This paper discusses reconfigurability issues in lowpower hand-held multimedia systems, with particular emphasis on energy conservation. We claim that a radical new approach has to be taken in order to fulfill the requirements - in terms of processing power and energy consumption - of future mobile applications. A reconfigurable systems-architecture in combination with a QoS driven operating system is introduced that can deal with the inherent dynamics of a mobile system. We present the preliminary results of studies we have done on reconfiguration in hand-held mobile computers: by having reconfigurable media streams, by using reconfigurable processing modules and by migrating functions

Digital simulation of chronopotentiometric and steady-state voltammetric curves at microelectrodes in the presence of a low concentration of supporting electrolyte

A simulation scheme for the calculation of theoretical chronopotentiograms at microelectrodes in solutions containing low amounts of supporting electrolyte is presented. The scheme allows computation of the changes in the concentration profiles of the substrates, products and the supporting electrolyte ions with time. The electrode potentials that are established after reaching the steady-state, together with the appropriate current intensities, can be used for constructing the steady-state voltammograms. The simulation of the mixed diffusional and migrational transport is based on the Crank-Nicolson method with an exponentially expanding time and space grids. The scheme does not impose any limitations on diffusion coefficients and it can be applied both to simple electrode reactions (one reactant-one product) and more complicated reactions under the assumption that the double-layer thickness is small in comparison to the diffusion layer. Five simple types of electrode reactions and an example of a more complicated scheme were considered. The results obtained demonstrate that the dependence of the steady-state limiting current on the support ratio (csupp.el./csubst) depends not only on the charge of the reactant and the product, but also on the diffusion coefficient ratio of the substrate and product. If the difference between diffusion coefficients is large, the predictions based on simpler theories available in literature can become invalid

Mindfulness:Een studie naar de effecten van Mindfulness-Based Cognitive Therapy en Mindfulness-Based Stress Reduction

Interventies die gebaseerd zijn op oefening in mindfulness staan de laatste jaren erg in de belangstelling. De training waarin oosterse meditatie oefening samen komt met de moderne westerse psychologie neemt nog altijd toe in populariteit (Brown e.a., 2007). Grondlegger is John Kabat-Zinn; die ontwikkelde de aandachtstraining, een techniek om mensen te leren om gaan met stress, angst, pijn en ziekte (Baer, 2003). Ook bij het Centrum Integrale Psychiatrie van Lentis Groningen worden sinds januari 2006 mindfulness trainingen gegeven, aan zowel cliënten als medewerkers. Is het enthousiasme gerechtvaardigd? Dit artikel bestaat uit twee delen. In het eerste deel wordt beschreven wat onder mindfulness verstaan wordt en hoe mindfulness trainingen in zijn werk gaan. Ook wordt in dit deel een literatuuroverzicht gegeven van onderzoeken naar de effecten van op mindfulness gebaseerde trainingen. In het tweede deel worden de resultaten gepresenteerd van een evaluatiestudie naar de mindfulness trainingen die de afgelopen jaren werden gegeven bij het Centrum Integrale Psychiatrie van Lentis

Field transformations and simple models illustrating the impossibility of measuring off-shell effects

In the context of simple models illustrating field transformations in Lagrangian field theories we discuss the impossibility of measuring off-shell effects in nucleon-nucleon bremsstrahlung, Compton scattering, and related processes. To that end we introduce a simple phenomenological Lagrangian describing nucleon-nucleon bremsstrahlung and perform an appropriate change of variables leading to different off-shell behavior in the nucleon-nucleon amplitude as well as the photon-nucleon vertex. As a result we obtain a class of equivalent Lagrangians, generating identical S-matrix elements, of which the original Lagrangian is but one representative. We make use of this property in order to show that what appears as an off-shell effect in an S-matrix element for one Lagrangian may originate in a contact term from an equivalent Lagrangian. By explicit calculation we demonstrate for the case of nucleon-nucleon bremsstrahlung as well as nucleon Compton scattering the equivalence of observables from which we conclude that off-shell effects cannot in any unambiguous way be extracted from an S-matrix element. Finally, we also discuss some implications of introducing off-shell effects on a phenomenological basis, resulting from the requirement that the description of one process be consistent with that of other processes described by the same Lagrangian.Comment: 19 pages, Latex, using RevTe

Channel Communication and Reconfigurable Hardware

Many applications can be structured as a set of processes or threads that communicate via channels. These threads can be executed on various platforms (e.g. general purpose CPU, DSP, FPGA, etc). In our research we apply channels as a basic communication mechanism between threads in a reconfigurable system. The research involves providing system level functions to describe the setup of communicating threads, which may now either run timeshared on a general CPU or in dynamically-setup special purpose logic that runs on reconfigurable hardware. The use of channels and threads running in both software and hardware, will be made transparent for the application level programmers by the system level functions. By first describing the threads and how they are connected and then letting the operating system decide on 'geographical' placement of the threads and buffers, multiprogramming will be supported and programs will be able to run on different setups of hardware (i.e. different amount of CPUs or available programmable logic). This is an ongoing work, the paper is a collection of thoughts, which lead to a first setup of rudimentary support functions in the operating system