848 research outputs found
Sample Dominance Aware Framework via Non-Parametric Estimation for Spontaneous Brain-Computer Interface
Deep learning has shown promise in decoding brain signals, such as
electroencephalogram (EEG), in the field of brain-computer interfaces (BCIs).
However, the non-stationary characteristics of EEG signals pose challenges for
training neural networks to acquire appropriate knowledge. Inconsistent EEG
signals resulting from these non-stationary characteristics can lead to poor
performance. Therefore, it is crucial to investigate and address sample
inconsistency to ensure robust performance in spontaneous BCIs. In this study,
we introduce the concept of sample dominance as a measure of EEG signal
inconsistency and propose a method to modulate its effect on network training.
We present a two-stage dominance score estimation technique that compensates
for performance degradation caused by sample inconsistencies. Our proposed
method utilizes non-parametric estimation to infer sample inconsistency and
assigns each sample a dominance score. This score is then aggregated with the
loss function during training to modulate the impact of sample inconsistency.
Furthermore, we design a curriculum learning approach that gradually increases
the influence of inconsistent signals during training to improve overall
performance. We evaluate our proposed method using public spontaneous BCI
dataset. The experimental results confirm that our findings highlight the
importance of addressing sample dominance for achieving robust performance in
spontaneous BCIs.Comment: 5 pages, 2 figure
Kraft und Beweglichkeit der Schulter bei koreanischen Volleyballspielern unterschiedlicher Spielklassen und Spielpositionen
Zusammenfassung
Ziel der vorliegenden Untersuchung war es, mit isokinetischen und kinematischen Methoden umfassendere und prĂ€zisere Ergebnisse fĂŒr die PrĂ€vention im Volleyball aufzuzeigen. HierfĂŒr wurden isokinetische Kraft- und kinematische Beweglichkeitsmessungen durchgefĂŒhrt, um die muskulĂ€ren VerhĂ€ltnisse des Schultergelenkes genauer zu untersuchen.
Bei der vorliegenden Studie nahmen 86 Probanden aus vier unterschiedlichen Spielklassen teil. 21 Probanden wurden aus der Profiliga rekrutiert, 24 aus der Uni-Liga, 21 aus dem Schulsport-Turnier, 20 in der Kontrollgruppe. FĂŒr die Innen- und AuĂenrotation des Schultergelenkes wurden konzentrische Messungen des maximalen Drehmoments durchgefĂŒhrt. Sowohl die dominante, als auch die nichtdominante Schulter wurden bei Winkelgeschwindigkeiten von 60 °âs und 180 °âs auf das maximale Drehmoment getestet. Die Beweglichkeitmessung der Schulter wurde mit einer dreidimensionalen Bewegungsanalyse durchgefĂŒhrt.
Die vorliegenden Ergebnissen zeigen, dass die Profiligaspieler bei den Winkelgeschwindigkeiten von 60 °/s mit 65,9 Nm die höchsten Werte aller Spielklassen beim maximalen Drehmoment der IRO an der dominanten Seite aufwiesen. Die Profi - Spielerinnen zeigten mit 48 % das niedrigste VerhĂ€ltnis von ARO / IRO. Bei den Profiligaspielern ergab die Messung der maximalen Innenrotationsbeweglichkeit an der dominanten Seite eine deutliche EinschrĂ€nkung gegenĂŒber der nichtdominante Seite. Die Profi - Spieler zeigten mit 45 % das niedrigste VerhĂ€ltnis von maximaler IRO zu ARO von allen Spielklassen. Beim Vergleich der Ergebnisse von Angriffsspielern zeigten sich Unterschiede des maximalen Drehmoments (60 °/s) mit IRO und ARO (DS), der maximalen Schulterrotation (DS) und VerhĂ€ltnis von maximaler AuĂen- zu Innenrotation an der dominanten Seite. Die Spieler mit frĂŒheren Schultergelenkverletzungen zeigten Unterschiede im maximalen Drehmoments bei ARO (60 °/s) (DS), maximalen DrehmomentverhĂ€ltnis zwischen ARO und IRO (60 °/s), sowie der maximalen Schulterrotation.
Die PrĂ€vention sind hier der Ausgleich der muskulĂ€ren Dysbalance mit Behebung sowohl der VerkĂŒrzungen, als auch der AbschwĂ€chungen. Solche Dysbalancen lassen sich frĂŒhzeitig diagnostizieren. Die untersuchten Ligen in der vorliegenden Studie gleichen sich bezĂŒglich des Verletzungsrisikos, wobei dies fĂŒr die Schulsportspieler nur in vermindertem Umfang galt. Wie schon seit einigen Jahren gefordert wird, muss der VerletzungsprĂ€vention im Training eine gröĂere Bedeutung beigemessen werden.
Abstract
The Shoulder overuse injuries are common in volleyball players, especially during spike motion. Muscle strength and range of motion of the shoulder rotation are considered to be important during spiking. It would also be worth to find out if there were differences in shoulder strength and range of motion among these volleyball players with and without shoulder injury history in order to design appropriate shoulder injury rehabilitation and prevention training programs for each player.
In this study, 86 players from 4 different levels were tested, 21 from the professional league, 24 from the university league, 21 from the middle- and high school league and the rest 20 from the control group.
Isokinetic concentric strength of the shoulder rotators were tested at angular velocities of 60°/s and 180°/s by using the Biodex, and passive range of motion of the shoulder rotation was assessed using with the Simi-motion.
The strength test shows that the highest torque of 65.9Nm (60 °/s) on the dominant side was measured in the professional league players and it was the highest among the 4 test groups.
The 48% of professional players show the lowest level of the ER/IR values and the 45% on the dominant side of professional players the lowest level of âmax. IR to ER,â which is the lowest of all test player groups. According to the test results, the dominant side shows the clear limitation of elasticity of inner rotation among professional league players (compared to the non-dominant side).
According to the test results in the attackers, the differences are to see in following factors like a isokinetic strength (60 °/s) of IR and ER (DS), maximal value of shoulder rotation (DS) and the ratio between the maximal ER and the IR on the dominant side.
The players who were injured in the history of shoulder show the differences in the isokinetic strength of ER (60 °/s), the strength ratio between ER and IR (60 °/s) and the maximal shoulder rotation (compared to the players without injury in the past).
We recommended functional exercises that improve both external rotators strength and stretching exercise for internal rotation in the dominant side during the prevention programs in volleyball players. In addition, hypermobility in the external rotation of dominant side for volleyball players should be looked over to prevent the injury
Channel Optimized Visual Imagery based Robotic Arm Control under the Online Environment
An electroencephalogram is an effective approach that provides a
bidirectional pathway between the user and computer in a non-invasive way. In
this study, we adopted the visual imagery data for controlling the BCI-based
robotic arm. Visual imagery increases the power of the alpha frequency range of
the visual cortex over time as the user performs the task. We proposed a deep
learning architecture to decode the visual imagery data using only two channels
and also we investigated the combination of two EEG channels that has
significant classification performance. When using the proposed method, the
highest classification performance using two channels in the offline experiment
was 0.661. Also, the highest success rate in the online experiment using two
channels (AF3-Oz) was 0.78. Our results provide the possibility of controlling
the BCI-based robotic arm using visual imagery data.Comment: 4 pages, 2 figures, 3 table
Demonstration of P-Type Stack-Channel Ternary Logic Device Using Scalable Dntt Patterning Process
A p-type ternary logic device with a stack-channel structure is demonstrated using an organic p-type semiconductor, dinaphtho[2,3-b:2\u27,3\u27-f]thieno[3,2-b]thiophene (DNTT). A photolithography-based patterning process is developed to fabricate scaled electronic devices with complex organic semiconductor channel structures. Two layers of thin DNTT with a separation layer are fabricated via the low-temperature deposition process, and for the first time, p-type ternary logic switching characteristics exhibiting zero differential conductance in the intermediate current state are demonstrated. The stability of the DNTT stack-channel ternary logic switch device is confirmed by implementing a resistive-load ternary logic inverter circuit
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