arXiv subjects

Frank Borg

Publications and source records attributed to Frank Borg.

4 recordsLinked to original sources

arXiv2014

Analyzing biosignals using the R freeware (open source) tool

For researchers in electromyography (EMG), and similar biosginals, signal processing is naturally an essential topic. There are a number of excellent tools available. To these one may add the freely available open source statistical software package R, which is in fact also a programming language. It is becoming one the standard tools for scientists to visualize and process data. A large number of additional packages are continually contributed by an active community. The purpose of this paper is to alert biomechanics researchers to the usefulness of this versatile tool. We discuss a set of basic signal processing methods and their realizations with R which are provided in the supplementary material. The data used in the examples are EMG and force plate data acquired during a quiet standing test.

physics.data-an↗

arXiv2010

Filter banks and the "Intensity Analysis" of EMG

Vinzenz von Tscharner (2000) has presented an interesting mathematical method for analyzing EMG-data called "intensity analysis" (EMG = electromyography). Basically the method is a sort of bandpassing of the signal. The central idea of the method is to describe the "power" (or "intensity") of a non-stationary EMG signal as a function both of time and of frequency. The connection with wavelet theory is that the filter is constructed by rescaling a given mother wavelet using a special array of scales (center frequencies) with non-constant relative bandwidth. Some aspects of the method may seem a bit ad hoc and we have therefore undertaken a closer mathematical investigation, showing the connection with the conventional wavelet analysis and giving a somewhat simplified formulation of the method using Morlet wavelets. It is pointed out that the "intensity analysis" method is related to the concept of an equalizer. In order to illustrate the method we apply it to nonstationary EMG-signals of a dynamic leg-extension force-velcity tests. (Data provided by Taija Finni, University of Jyväskylä.)

physics.data-an↗

arXiv2006

Quantum profiles and paradoxes

This paper discusses questions concerning the foundations of quantum mechanics (entanglement, wave collapse, irreversibility) with reference to the issues raised during a Minisymposium held in Helsinki, 1.6-3.6 in 1992, where A Shimony, A Peres and B d'Espagnat were invited to lecture. The measurement problem is related to the phenomenon of irreversibility which is known not to follow from any fundamental theory; e.g., the law of exponential decay does not follow from the Schrödinger equation in senso stricto. The approximations that lead to irreversibility are related to some form of ''forgetting'', or coarse graining. Some approaches to the question, why these approximations can be justified, are reviewed. The paper also discusses dynamical reduction schemes and it is suggested, that the corresponding non-linear modifications of the Schrödinger equation -- which lead to non-conservation of energy -- are actually ''effective'' Schrödinger equations for open systems (in analogy with the ''effective'' Lagrangians in QFT). Thus these modifications should be derived from a fundamental theory of interactions. The paper ends with some brief comments on the mind-body question in the quantum mechanical context. A postscript has been added (2006).

physics.gen-ph↗

arXiv2005

An inverted pendulum with a springy control as a model of human standing

The normal and the inverted pendulum continue to be one of the main physical models and metaphors in science. The inverted pendulum is also a classic study case in control theory. In this paper we consider a special demonstration version of the inverted pendulum which is controlled via a spring. If the spring constant is below a critical level the springy control will be unstable and the pendulum will be kept from falling only by exercising a dynamically varying control. This situation resembles the case of human bipedal quiet standing with the Achilles tendon serving as the spring. The paper is written with physics students in mind.

physics.bio-ph↗