Tremor classification and tremor time series analysis

The separation between physiologic tremor (PT) in normal subjects and the pathological tremors of essential tremor (ET) or Parkinson's disease (PD) was investigated on the basis of monoaxial accelerometric recordings of 35 s hand tremor epochs. Frequency and amplitude were insufficient to separate between these conditions, except for the trivial distinction between normal and pathologic tremors that is already defined on the basis of amplitude. We found that waveform analysis revealed highly significant differences between normal and pathologic tremors, and, more importantly, among different forms of pathologic tremors. We found in our group of 25 patients with PT and 15 with ET a reasonable distinction with the third momentum and the time reversal invariance. A nearly complete distinction between these two conditions on the basis of the asymmetric decay of the autocorrelation function. We conclude that time series analysis can probably be developed into a powerful tool for the objective analysis of tremors. (c) 1995 American Institute of Physics.     

All-Weather Comparison between Spectral and Broadband (Robertson-Berger) UV Measurements

Abstract— Spectral measurements of UV irradiance at the Fraunhofer Institute at Garmisch-Partenkirchen, Germany, are intercompared with data from two different Robert-son-Berger-type meters. More than 21000 spectra gathered during 20 months of continuous operation were used for this analysis, sampling a large variety of atmospheric conditions. At low solar zenith angles the agreement (± 10%) was quite satisfactory, whereas at high solar zenith angles the broadband instruments gave systematically lower readings than the erythemally weighted spectral data. The deviation of the spectral response of the broadband instruments from the Commission Internationale de 1'Eclairage (CIE) erythema function and the cosine error provide an explanation of the observed differences that are similar for both broadband meters. Model calculations agree quite well with the observations, if an accurate measurement of the broadband spectral response is available. An analytical fit curve was established for the ratio between broadband and weighted spectral data, as a function of solar zenith angle, enabling quick and easy checks of the stability of the spectrora-diometric system. The relative standard deviation of the data from the fit function was only2–3% in the case of cloudless sky conditions and 5% for all sky conditions, including all types of systematic and instrumental errors.     

Angle resolved ion scattering spectroscopy at surfaces of pure liquids: topography and orientation of molecules

The topography of a liquid surface has not been the subject of experimental research because of a lack of experimental methods. The hereby outlined investigation shows how the topography of a liquid surface can be classified through the angular mode of neutral impact collision ion scattering spectroscopy. It further shows how concentration depth profiles with a high depth resolution are gained. These can be used as the basis to determine quantitatively the orientation of molecules. The substances investigated are the polar solvents formamide and benzyl alcohol.     

Kurtosis-Based Symbol Timing and Carrier Phase/Frequency Tracking

Kurtosis is known to be effective at estimating signal timing and carrier phase offset when the processing is performed in a “burst mode,” that is, operating on a block of received signal in an offline fashion. In this paper, kurtosis-based estimation is extended to provide tracking of timing and carrier phase, and frequency offsets. The algorithm is compared with conventional PLL-type timing/phase estimation and shown to be superior in terms of speed of convergence, with comparable variance in the matched filter output symbols.     

Viewing the effective k-space coverage of MR images: phantom experiments with fast Fourier transform

The purpose of this experimental study was to evaluate whether the effective k-space coverage of MR images can in principle be viewed after multidimensional Fourier transform back to k-space.     

Formation of polymer-modified electrodes from 2-mercaptobenzoxazole in aqueous solution

A polymer-modified electrode can be formed from 2-mercaptobenzoxazole (MBO) on glassy carbon (GC) electrodes in aqueous solution. Film formation occurs during prolonged cycling with positive scan limits above +600 mV vs. SCE. The main redox process is the oxidation of MBO to bis(benzoxazolyl) disulfide and the re-reduction to MBO. However, several side reactions including polymerization are observed. A density functional calculation of the MBO radical shows that there is a considerable spin density not only at the sulfur atom but also at the nitrogen atom and at some of the carbon atoms. Therefore ring-ring coupling products other than the disulfide can be formed which may further react to the polymer film. Notably, FTIR spectra indicate substitution at the nitrogen atom. The coupling would explain the occurrence of both thione and bridging sulfur as well as amine and imine nitrogen in the formed polymer. These binding states in the film have been identified by X-ray photoelectron spectroscopy (XPS). Elemental sulfur could not be detected by cyclic voltammetry or XPS of cooled samples. The polymer film is not redox active and non-conducting, as illustrated by the self-limiting growth and the diminishing currents during the potentiodynamic film growth. The film is impermeable for anions. At pH 7 the film is permeable for cations, while it is impermeable for anions and cations at pH 4. Electronic Publication