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Biomedical subjects

G Holzmüller

Publications and source records attributed to G Holzmüller.

5 recordsLinked to original sources
PubMed1996

A new method of fitting and analysis of simple uni-joint arm movements.

A new method for fitting and analysis of simple uni-joint arm movements is proposed. The method is based on a model which postulates that the acceleration-time profile of the movement can be described by a linear combination of two Gaussian functions (positive for acceleration and negative for deceleration). The method was tested on more than 21000 arm movements performed under different control conditions and showed high fitting precision. It allows to completely describe a movement using only five parameters of two Gaussian functions. The method is sensitive to differences between the acceleration and deceleration phases of movement as well as between subsequent movements because of the independent calculation of the Gaussian functions for accelerative and decelerative movement parts. Relationships between conventional kinematic and model parameters as well as areas of application of the method are discussed.

Algorithms↗
PubMed1996

[Determination of back shape in median sagittal plane using an inclination sensory].

The measurement and assessment of the shape of the human back is in the process of becoming an important area of research. Various measuring techniques have already been developed, including moiré topography, stereoscopic photography and raster stereography. These have been employed in the evaluation of scoliosis, kyphosis, funnel chest and other pathological conditions of the spine. These systems are very complicated (and expensive) since they involve a three-dimensional analysis of the shape of the back. For preventive medical purposes, however, evaluation of the spine in the median sagittal plane alone often suffices. In this study, the inclinations of the back along the spine were measured, and it has been shown that these measurements can be used to reconstruct the shape of the back.

Anthropometry↗
PubMed1992

[Movement analysis with microgravitation: theory and practical aspects for the calculation of target movements with the MONIMIR helmet lamp].

A new optoelectronic system for movement analysis is introduced. This equipment was employed with success during an Austrian-Soviet space flight. The method for the determination of position and orientation is described with the aid of an example, namely the determination of the location of the intersection of a beam of light generated by a helmet-mounted lamp with a screen.

Electrooculography↗
PubMedDate not supplied

The effect of head-to-trunk position on the direction of arm movements before, during, and after space flight.

This contribution deals with the examination of the consequences of different head-to-trunk positions on arm movements under normal gravity and during prolonged space flight. One of the objectives of this study was to investigate the influence of weightlessness on the condition of the spatial analysis system. Aimed arm movements in the horizontal plane (pointings towards two visual targets) were recorded, first with eyes open, head straight (learning part), then with eyes closed, head straight and during yaw or roll position of the head (performance part). Measurements related to these different head-to-trunk-positions were taken in one short-term and nine long-term cosmonauts preflight, inflight, and postflight. Terrestrial control experiments were carried out with an extended experimental design in 14 healthy volunteers. The analysis of these experiments revealed that, with eyes closed and the head in yaw position, cosmonauts before flight and control subjects exhibit significant slants of the movement plane of the arm. Contrary to terrestrial measurements, in space experiments roll tilt of the head to the right is correlated with considerable counterclockwise slant of the movement plane. This slant of the movement plane of the arm was interpreted as tilt of the internal representation of the horizontal coordinate. The effect is larger with greater distortion induced by the changed head position and with larger muscular involvement to keep this position. This effect is also increased by the reduction of information (for example, in microgravity). The amount and the direction of the horizontal offset of the arm movements are shown to be dependent on the head-to-trunk position, too. Additionally, we have found changes in the amplitude and in the duration of the arm movement, in the vertical offset, and in the curvature of the movement paths, depending on the experimental conditions.

Adult↗