659 research outputs found
Multi-segmental movement patterns reflect juggling complexity and skill level
No full textThe juggling action of six experts and six intermediates jugglers was recorded with a motion capture system and decomposed into its fundamental components through Principal Component Analysis. The aim was to quantify trends in movement dimensionality, multi-segmental patterns and rhythmicity as a function of proficiency level and task complexity. Dimensionality was quantified in terms of Residual Variance, while the Relative Amplitude was introduced to account for individual differences in movement components. We observed that: experience-related modifications in multi-segmental actions exist, such as the progressive reduction of error-correction movements, especially in complex task condition. The systematic identification of motor patterns sensitive to the acquisition of specific experience could accelerate the learning process
High-voltage capacitively coupled contactless conductivity detection for conventional and microchip capillary electrophoresis
No full textThis thesis focuses on the optimisation of capacitively coupled contactless conductivity detection for capillary and microchip electrophoresis and its applications in analytical chemistry. First, the effect of high excitation voltages and operation frequencies on the capacitively coupled contactless conductivity detector cell for conventional capillary electrophoresis is evaluated. The detector electrodes comprised two steel tubes cut from hypodermic needles, through which the capillaries were inserted. It is demonstrated that increasing excitation voltages from 25 V pp, to 250 Vpp improves the detection limits by a factor of 10. The high actuator voltage approach was also investigated for contactless conductivity detection on a glass-microchip device with ancm long channel. The detector electrodes formed part of the microchip and were placed on the microchip directly above the microchannel. In a separate project the simplification of on-microchip contactless conductivity detection was accomplished. This was achieved by integrating the detector electrodes on to a chip-holder specifically designed for this purpose. Thus the electrodes were a part of the holder, an improvement of the previous arrangement whereby the detector electrodes were situated on the microdevice. Finally the applications and advantages of the optimised high-voltage capacitively coupled contactless conductivity detection for inorganic and organic analysis were demonstrated. The separation and detection of 14 metal ions was accomplished in less than six minutes. The compatibility of this detector with non-UV transparent, polymer capillaries has been demonstrated. The detection of native amino acids has been evaluated. Part of the work was dedicated to the on-chip analysis of various classes of organic ions. The two immunoproteins human immunoglobulin M (IgM) and immunoglobulin G (IgG), were analysed in their unlabelled state on both capillary and lab-on-chip platforms. All species involved in an immunological interaction between IgM and IgG could be detected. A method for the analysis of selected basic pharmaceutical drug substances was developed. Detection limits comparable to those supplied by direct UV detection were obtained. Main component assays of selected pharmaceutical preparations have been demonstrated
Quantifying instantaneous performance in alpine ski racing
No full textAlpine ski racing is a popular sport in many countries and a lot of research has gone into optimising athlete performance. Two factors influence athlete performance in a ski race: speed and the chosen path between the gates. However, to date there is no objective, quantitative method to determine instantaneous skiing performance that takes both of these factors into account. The purpose of this short communication was to define a variable quantifying instantaneous skiing performance and to study how this variable depended on the skiers' speed and on their chosen path. Instantaneous skiing performance was defined astime loss per elevation difference dt/dz, which depends on the skier's speed v(z), and the distance travelled per elevation difference ds/dz. Using kinematic data collected in an earlier study, it was evaluated how these variables can be used to assess the individual performance of six ski racers in two slalom turns. The performance analysis conducted in this study might be a useful tool not only for athletes and coaches preparing for competition, but also for sports scientists investigating skiing techniques or engineers developing and testing skiing equipment
A novel approach to solve the “Missing marker problem” in marker-based motion analysis that exploits the segment coordination patterns in multi-limb motion data
No full textMarker-based human motion analysis is an important tool in clinical research and in many practical applications. Missing marker information caused by occlusions or a marker falling off is a common problem impairing data quality. The current paper proposes a conceptually new gap filling algorithm and presents results from a proof-of-principle analysis. The underlying idea of the proposed algorithm was that a multitude of internal and external constraints govern human motion and lead to a highly subject-specific movement pattern in which all motion variables are intercorrelated in a specific way. Two principal component analyses were used to determine how the coordinates of a marker with gaps correlated with the coordinates of the other, gap-free markers. Missing marker data could then be reconstructed through a series of coordinate transformations. The proposed algorithm was tested by reconstructing artificially created gaps in a 20-step walking trial and in an 18-s one-leg balance trial. The measurement accuracy’s dependence on the marker position, the length of the gap, and other parameters were evaluated. Even if only 2 steps of walking or 1.8 s of postural sway (10% of the whole marker data) were provided as input in the current study, the reconstructed marker trajectory differed on average no more than 11 mm from the originally measured trajectory. The reconstructed result improved further, on average, to distances below 5 mm if the marker trajectory was available more than 50% of the trial. The results of this proof-of-principle analysis supported the assumption that missing marker information can be reconstructed from the intercorrelations between marker coordinates, provided that sufficient data with complete marker information is available. Estimating missing information cannot be avoided entirely in many situations in human motion analysis. For some of these situations, the proposed reconstruction method may provide a better solution than what is currently available
Trajectory of the left knee marker (LKNE) recorded for 20 steps of walking.
No full text<p>In this example, the first 10 steps (frame 1-2150) of the measured LKNE-coordinates were used as input data for the reconstruction, the following 10 steps (frame 2151-4300) were reconstructed.</p
Der deutsch-russische Unternehmer Andreas Knauf im Ural Der Аufstieg
No full textHans Peter Andreas Knauf, known in Russia as Andrey Andreevich Knauf (1765 – 1835), is an uncommon figure in Russian history. His life leaves many questions that are still to be answered. He was, however, an outstanding personality that played a significant role in the development of the mining and iron foundry industries in the Urals. Born in Kiel, the capital of the Duchy of Holstein, Andrey Knauf, a son of a shoemaker who had neither capital nor connections, was a talented autodidact, and a fellow-countryman of Emperor Peter III. He came to Russia at the age of 18 and achieved considerable success in commerce becoming a prominent merchant of the top guild in Moscow and a manufacturer in the Urals. The article focuses on Knauf ’s activity in the Urals as an owner of mining factories and on their modernization by transferring German technologies, especially in 1801–1811. His experience is interesting in the context of serfdom and the lack of trained workers in the system of possessional manufactures. However, to study the problem in question the author considers it reasonable not to confine to the meta-concepts of autocracy and serfdom, which are perceived as interpretative patterns for the period in question, but to complete those meta-concepts with micro-historical sketches focusing on “particular” facts and the role of an individual in history.Ганс Петер Андреас Кнауф (1765 – после 1835), в России – Андрей Андреевич Кнауф – необычный феномен русской истории. Его жизненный путь оставляет много вопросов, ответы на которые до сих пор не найдены. Но в одном можно быть совершенно уверенным: Андрей Кнауф является выдающейся личностью в горнодобывающей и чугунолитейной промышленности Урала.Уроженец столицы герцогства Гольштейнского города Киля и земляк российского императора Петра III, Андрей Кнауф, сын сапожника без связей и капитала, но талантливый автодидакт, прибыв в Петербург 18-летним юношей, добивается головокружительных успехов на купеческом поприще, становится именитым купцом 1-й гильдии московского купечества и заводчиком на Урале. Исследуется аспект его деятельности на Урале в качестве владельца горнозаводских предприятий, модернизированных за счет трансфера немецких технологий, особенно с 1801 по 1811 г. Его опыт интересен в контексте крепостного права и нехватки квалифицированных кадров при существовавшей системе посессионных заводов. Для разработки данной темы целесообразно все же не ограничиваться метапонятиями «самодержавия» и «крепостничества», служащими интерпретационными образцами исторической картины исследуемого периода, но стараться дополнить их микроисторическими зарисовками, используя «частные» факторы и «роль личности в истории»
Mean of the difference (absolute values) between predicted and measured marker trajectories in the one-leg balance trial.
No full text<p>Mean of the difference (absolute values) between predicted and measured marker trajectories in the one-leg balance trial.</p
Accuracy if the reconstruction was based on a selected number of PC-vectors.
No full text<p>(LKNE: left knee, LSHO: left shoulder, and LWRA: left wrist marker). The broken vertical line highlights the results obtained with 40 PC-vectors, which was used as standard for all other analyses in the current study.</p
Maximum of the difference (absolute values) between predicted and measured marker trajectories in the walking trial.
No full text<p>Maximum of the difference (absolute values) between predicted and measured marker trajectories in the walking trial.</p
Maximum of the difference (absolute values) between predicted and measured marker trajectories in the one-leg balance trial.
No full text<p>Maximum of the difference (absolute values) between predicted and measured marker trajectories in the one-leg balance trial.</p
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