David Liljequist

Learn More
The epitaxial film of the highly enriched 76 Ge isotope (average mass 75.63) was grown on an intrinsic Ge(111) substrate in an ultrahigh vacuum system (base pressure 10 Ϫ11 mbar) by molecular beam epi-taxy at a substrate temperature of 720 K, well below the threshold for bulk interdiffusion [H. D. Fuchs et al., Phys. Rev. B 51, 16817 (1995)]. Before and(More)
The recovery of the median frequency of the power spectrum of the electromyogram (EMG) after fatigue has been studied to obtain reference data for healthy subjects (n = 55). In a seated position, the subjects performed a 45 s isometric back muscle contraction at 80% of maximal voluntary contraction, followed by 5 s contractions after 1, 2, 3, and 5 min in(More)
In order to study the influence of interelectrode distance and force level on the electromyographic (EMG) spectral parameters and on their reliability, bipolar surface EMG measurements were performed on the lumbar muscles of 15 subjects. Two test contractions (45 s) at 40% of maximal voluntary contraction (MVC) were performed, one with 2 cm interelectrode(More)
The purpose of this paper has been to review the current status and progress of the field of radiation biophysics, and draw attention to the fact that physics, in general, and radiation physics in particular, with the aid of mathematical modeling, can help elucidate biological mechanisms and cancer therapies. We hypothesize that concepts of condensed-matter(More)
PURPOSE Elastic scattering is important for the spatial distribution of electrons penetrating matter, and thus for the distribution of deposited energy and DNA damage. Scattering media of interest are in particular liquid and gaseous water and gaseous nitrogen. The former are used as surrogates for tissue and cell environments (since more than 70% of the(More)
PURPOSE Backscattering of very low energy electrons in thin layers of amorphous ice is known to provide experimental data for the elastic and inelastic cross sections and indicates values to be expected in liquid water. The extraction of cross sections was based on a transport analysis consistent with Monte Carlo simulation of electron trajectories.(More)