No abstract

Techniques to quantify postural stability usually rely on the evaluation of only two variables, that is, two coordinates of COP. However, by using three variables, that is, three components of acceleration vector, it is possible to describe human movement more precisely. For this purpose, a single three-axis accelerometer was used, making it possible to evaluate 3D movement by use of a novel method, convex polyhedron (CP), together with a traditional method, based on area of the confidence ellipse (ACE). Ten patients (Pts) with cerebellar ataxia and eleven healthy individuals of control group (CG) participated in the study. The results show a significant increase of volume of the CP (CPV) in Pts or CG standing on foam surface with eyes open (EO) and eyes closed (EC) after the EC phase. Significant difference between Pts and CG was found in all cases as well. Correlation coefficient indicates strong correlation between the CPV and ACE in most cases of patient examinations, thus confirming the possibility of quantification of postural instability by the introduced method of CPV.

No abstract

Abstract. Current techniques for quantifying human postural stability during quiet standing have several limitations. The main problem is that only two movement variables are evaluated, though a better description of complex three-dimensional (3-D) movements can be provided with the use of three variables. A single tri-axial accelerometer placed on the trunk was used to measure 3-D data. We are able to evaluate 3-D movements using a method based on the volume of confidence ellipsoid (VE) of the set of points obtained by plotting three accelerations against each other. Our method was used to identify and evaluate pathological balance control. In this study, measurements were made of patients with progressive cerebellar ataxia, and also control measurements of healthy subjects, and a statistical analysis was performed. The results show that the VEs of the neurological disorder patients are significantly larger than the VEs of the healthy subjects. It can be seen that the quantitative method based on VE is very sensitive for identifying changes in stability, and that it is able to distinguish between neurological disorder patients and healthy subjects.

With the expanding electrification in all sectors of transport, it is necessary to look for new efficient solutions for propulsion systems for use in air transport. One of the approaches can be the use of electric ducted fans (EDFs), especially in, but not limited to, the case of unmanned aerial vehicles with vertical takeoff and landing. This concept has been known for several decades but has been used very little and therefore has been almost unexplored. This opens up opportunities for investigating the performance characteristics, electrical consumption or efficient thrust vectoring of EDFs with respect to their design and operational use. The presented study therefore deals with the influence of the EDF design change on its performance characteristics. These design changes mainly concerned the geometry of the cowling, i.e., reduction and increase of outlet cross section, and arrangement of fans, i.e., one- and two-rotor specification. The comparison was based on measuring of vertical thrust and power consumption during static testing. The results showed that the increasing outlet is the most suitable construction for the generation of vertical thrust during static testing, considering the specifically used EDF construction arrangement. Based on the findings, it can also be concluded that EDFs are a suitable option for use in unmanned aircraft as a competition to other propulsion systems.

Nowadays, a high-induction magnetic stimulation is starting to be increasingly applied as a biophysical stimulation in the conservative treatment of the degenerative locomotor system diseases. These are mainly in correlation with the changes in soft tissue elasticity, which should be positively influenced by the flow-induced electrical currents of high current density during high-induction magnetic stimulation. This assumption was verified within the interventional and prospective study using the ultrasound elastography. The group consisted of 6 volunteers, whose elasticity of the patellar tendons was measured using the 2D shear-wave ultrasound elastography. The volunteers were then exposed to a 20-minute high-induction magnetic stimulation session with a frequency of 20 Hz, in 2 s package intervals, with a 5 s pause, and a induced electric current density of 100 Am−2 in the tendons area. A tendon tension was measured five times for all volunteers, where mean tension at the marked area of the tendon, as well as the highest point tension indicated by the Q-Box, was monitored. The measurement results show that high-induction magnetic stimulation has an influence on the patellar tendon tension change, which occurred in the case of all involved volunteers when the patellar tension was decreased.

During their professional career, pilots often experience a change in workplace conditions in the form of an aircraft cockpit ergonomics change. Change of working conditions may impact their perception of flight data or the pilot’s psychophysiological condition, especially in cases of inexperienced pilots. The presented study deals with the influence of cockpit ergonomics change on the performance and pilot workload during a training course. We divided 20 subjects with no previous practical flying experience into two training groups (Gr. A and Gr. B). The flight training was focused on acquisition of basic piloting skills where both groups experienced cockpit ergonomics change in different training phases. The performance (piloting precision) was assessed based on deviations from predetermined parameters of the monitored flight manoeuvres. Heart rate variability qualified the extent of workload. The study showed the influence of the cockpit arrangement on piloting precision, where the transition to other type of cockpit ergonomics did not influence pilots’ subjective workload with statistical significance.

Modern approaches to physical therapy often use electric currents induced by time-varying magnetic fields. Although some of these methods are already commonly used, and only a few studies are looking at applying particular techniques on exposed tissue. In this study, a high-induction magnetic stimulation (HIMS) was applied to the chest area to affect the electrical conduction system of the heart. The animal model Sus scrofa domesticus was used for the study. Standard methods were used to make the subsequent analysis, i.e., heart rate variability in time and frequency domain. Concerning the nonlinear character of the electrocardiographic signal and evaluating complex variability (complexity), recurrent quantification analysis was used. The results show high resistance to a physiologically working heart, but there are also specific changes concerning complex variability. Thus, the results indicate that the HIMS application in the chest area may not pose a significant risk to healthy individuals in terms of the short-term effect of this technique on cardiac activity. However, cardiac activity is still, to some extent, affected by the HIMS application. In view of this and the fact that the study was conducted on an animal model, further research in this area would be appropriate.