Visual and spatial audio mismatching in virtual environments

This paper explores how vision affects spatial audio perception in virtual reality. We created four virtual environments with different reverb and room sizes, and recorded binaural clicks in each one. We conducted two experiments: one where participants judged the audio-visual match, and another where they pointed to the click direction. We found that vision influences spatial audio perception and that congruent audio-visual cues improve accuracy. We suggest some implications for virtual reality design and evaluation

An exhibition on biomedical engineering for Vattenhallen Science Center LTH

This thesis contains the basis for an exhibition about biomedical engineering due to be displayed at Vattenhallen in the summer of 2013. The aim of the exhibition is to inspire and interest the children and adults that come and visits Vattenhallen. Hopefully at least one child will feel interested at study at LTH in the future. The basis contains 13 experimental stations and a short description of a potential laboration. Apart from these 13 stations three experiments have been constructed as well. An EMG-controlled prosthetic hand, an ultrasound phantom in the form of a 13 week old fetus and a software program for an experiment about MR/CT imaging. The experimental stations are: At the hospital Tissues MR Ultrasound The way through the stomach and bowel system Key hole surgery Your fantastic body The EMG controlled hand ECG Tinnitus Dialysis Microfluids The laboration: Servoventilato

The Effects of Static Stretching Versus Dynamic Stretching on Lower Extremity Joint Range of Motion, Static Balance, and Dynamic Balance

The purpose of this study was to examine the effects of static stretching (SS) versus dynamic stretching (SS) on lower extremity joint range of motion (ROM), static balance, and dynamic balance. Fifteen active subjects with tight hamstring and calf muscles participated. Hip flexion and knee extension ROM angle was measured using a fluid inclinometer. A closed-chain method of measuring ankle dorsiflexion ROM was used. Static balance was assessed in single-leg stance on a force plate using the time-to-boundary (TTB) measurement. The Star Excursion Balance Test (SEBT) was used to assess dynamic balance in three directions. These measurements were assessed before and after each of three interventions: DS, SS or warm-up alone (CN). The dependent variables included ROM measures (hip flexion, knee extension, and ankle dorsiflexion), SEBT measures (anterior (ANT), posterior-medial (PM), posterior-lateral (PL)), and TTB mean in anterior-posterior (AP) and medial-lateral (ML). Repeated measures ANOVA were used to analyze the data. There was a significant main effect (p \u3c 0.05) for time. Repeated measures ANOVA showed that knee extension ROM, hip flexion ROM, ankle dorsiflexion ROM, the SEBT (ANT, PM, PL) significantly (P\u3c0.05) increased regardless of what intervention (SS, DS, CN) was performed. There were no significant differences (p\u3e0.05) for the TTB (ML, AP) and there were also no significant interaction (p\u3e0.05) between interventions (SS, DS, CN) and time. The less stiff muscles and more slack connective tissue around the joints following stretching might attribute to the increased joint ROM. The enhanced ability to maintain dynamic balance after an increased flexibility might be due to a desensitized stretch reflex. A less responsive stretch reflex could suppress the postural deviations, enhance the proprioceptive input, and thus make it easier to establish equilibrium. Another contributor might be elevated muscle and body temperature, which enhance nerve conduction velocity. The sensory systems might play a dominant role in regulating the static postural control. Additional research is needed to more clearly understand the relationship between altered ROM, balance and stretching

Net Impulse and Net Impulse Characteristics in Vertical Jumping

The purpose of this dissertation was to explore the potential use of net impulse and its characteristics in vertical jumping to monitor athletes\u27 performance status and responses/adaptations to interventions. Five variables were proposed as net impulse characteristics: net impulse height and width, rate of force development, shape factor, and net impulse proportion. The following were then examined: 1) test-retest reliability of a new approach to identify net impulse in a force-time curve and of net impulse characteristics and criterion validity of the new approach; 2) effective measures of net impulse characteristics; 3) relationships between training-induced changes in its characteristics and force production ability. The following are major findings of the dissertation. Rate of force development particularly for the countermovement jump require a large magnitude of change to overcome the variable\u27s inherent variability. Shape factor and net impulse proportion for the static jump should be used with caution and requires further investigations. Alternative net impulse can be used interchangeably to criterion net impulse. Of the proposed net impulse characteristics, net impulse height and width and shape factor were found to contribute to countermovement jump height, whereas all the net impulse characteristics were found to contribute to static jump height. Of the characteristics found to contribute, relative net impulse height (net impulse height divided by system mass) appears to be an important characteristic to achieve a high jump height for the countermovement and static jumps and net impulse proportion for the static jump. A mechanism behind increased countermovement jump height may be an increased countermovement displacement as a result of increased force production ability. A mechanism behind increased static jump height is the increased proportion of the entire positive impulse occupied by net impulse (i.e. increased net impulse proportion). The findings of this dissertation show the possibility of the use of the net impulse characteristics to monitor athletes\u27 performance status and responses/adaptations to interventions. However, because this dissertation was the first to explore the potential use of the net impulse characteristics for athletes\u27 performance monitoring, the existing knowledge is still preliminary and further research is required before practical recommendations are made

Reward and punishment: the neural correlates of reinforcement feedback during motor learning

‘By the carrot or the stick’ reward or punishment has been contemplated by instructors to motivate their pupils to learn a new motor skill. The reinforcements of reward and punishment have demonstrated dissociable effects on motor learning with punishment enhancing the learning rate and reward increasing retention of the motor task. However it is still unclear how the brain processes reward and punishment during motor learning. This study sought to investigate the role of reinforcement feedback in cortical neural activity associated with motor learning. A novel visuomotor rotation task was employed with reward punishment or null feedback as the participants adapted their movement to a 30-degree counter-clockwise rotation. We measured movement time and task accuracy throughout the task. Surface electroencephalography was utilized to record cortical neural activity throughout the learning and retention of the motor task. Event-related potentials (ERPs) were calculated to assess how the brain processes the reinforcement feedback and prepares for movement. Repeated measures ANOVAs were utilized to detect differences in the movement parameters and ERP amplitudes. This study found that reward and punishment feedback did not produce different effects on the rate of task learning. However punishment feedback impaired the retention (memory) of the motor task. These behavioral effects were accompanied by changes in the amplitude of ERPs during feedback presentation and movement preparation. These results suggest that punishment feedback alters brain processes involved in memory formation during motor learning

Effects of Creatine-Electrolyte Supplement on Power and Strength Performance

The purpose of this study was to investigate the effects of a creatine and electrolyte formulated multi-ingredient performance supplement (MIPS) on strength and power performance. Maximal strength, total concentric work, mean rate of force development (mRFD), mean power, peak power, and peak force was determined at pre-test and post-test separated by six weeks of supplementation. Subject’s body density and body water were measured using a BodPod and Quantum X Bioelectrical Impedance unit respectively. Subjects performed three akimbo countermovement jumps (ACMJ) on a force platform. Subjects performed a one-repetition maximum (1RM) for back squat and bench press consisting of a maximal repetition test at a 90% predicted value. Eighty percent of the subjects pre-test 1RM was used for a maximal repetition test to test for performance variables including: total concentric work, mRFD, mean power, peak power, and peak force. Testing was separated by six weeks of supplementation in a double blind fashion with a placebo group for comparison. A two way mixed analysis of variance (ANOVA) was applied with an alpha level of 0.05 for all body composition, body water, akimbo countermovement jump, back squat, and bench press variables. The MIPS showed a significant increased back squat and bench press maximal strength (13.4%, p = 0.035 and 5.9%, p = 0.045 respectively), as well as total concentric work (26.5%, p = 0.024), mRFD (22.4%, p = 0.050), and mean power (17.9%, p = 0.025) for the maximal repetition bench press test at 80% of their 1RM. The placebo group had a significant decreased mRFD of -26% over the six-week supplementation. Creatine formulated with electrolytes could be beneficial for recreationally trained individuals

New Trends in Neuromechanics and Motor Rehabilitation

Neuromechanics has been used to identify optimal rehabilitation protocols that successfully improve motor deficits in various populations, such as elderly people and individuals with neurological diseases (e.g., stroke, Parkinson’s disease, and essential tremor). By investigating structural and functional changes in the central and peripheral nervous systems based on neuromechanical theories and findings, we can expand our knowledge regarding underlying neurophysiological mechanisms and specific motor impairment patterns before and after therapies to further develop new training programs (e.g., non-invasive brain stimulation). Thus, the aim of this Special Issue is to present the main contributions of researchers and rehabilitation specialists in biomechanics, motor control, neurophysiology, neuroscience, and rehabilitation science. The current collection provides new neuromechanical approaches addressing theoretical, methodological, and practical topics for facilitating motor recovery progress

Opções de movimentos na rotação da ginástica

Quando um ginasta executa um mortal, o momento linear e angular, juntamente com determinado controle de inércia durante a fase de voo, restringem as possibilidades de ação. Devido à complexidade e à natureza dinâmica do sistema do movimento humano, pode-se argumentar que existe determinada quantidade de estados coordenativos estáveis quando se executa mortais. O objetivo deste estudo foi explorar a multiplicidade de opções de movimento e estados coordenativos, juntamente com os seus parâmetros de diferenciação para um único mortal na ginástica, com base em um modelo matemático simples que reflita o comportamento da rotação do ginasta durante a fase de voo. Os parâmetros biomecânicos que determinam o comportamento da rotação durante um mortal variam sistematicamente em relação a determinado conjunto de restrições biomecânicas que definem a execução bem sucedida do mortal. Simulações em série revelaram que, a partir de 10229760 ciclos de simulação, somente 655346 (aproximadamente 6,41%) levaram ao desempenho bem sucedido do mortal. Uma análise subsequente da perspectiva de movimento para o momento angular ótimo revelou 10 estados de coordenação para um único mortal que poderiam ser claramente distinguidos com base nos parâmetros de simulação. Considerados os resultados em conjunto, torna-se evidente que seria mais aconselhável realizar um único mortal com momento de inércia maior quando se atinge a posição grupada, duração mais longa para atingir a posição grupada, duração mais longa da posição grupada, e um momento de inércia intermediário durante a aterrissagem. Essa estratégia compreende a maior quantidade de opções de movimento associados a uma aterrissagem na posição ereta e, assim, a maior probabilidade de sucesso quando se realiza um único mortal.When a gymnast performs a somersault, the linear and angular momentum along with a particular control of inertia during the flight phase constrain the possibilities for action. Given the complexity and dynamic nature of the human moving system, one could argue that there exist a particular amount of stable coordination states when performing somersaults. The goal of this study was to explore the manifold of movement options and coordination states along with their differentiating parameters for a single somersault in gymnastics based on a simple mathematical model reflecting gymnast’s rotation behavior during the flight phase. Biomechanical parameters determining rotation behavior during a somersault were systematically varied with regard to a particular set of biomechanical constraints defining a successful somersault performance. Batch simulations revealed that from 10229760 simulation cycles only 655346 (approximately 6.41%) led to successful somersault performance. A subsequent analysis of the movement option landscape for the optimum angular momentum revealed ten coordination states for a single somersault that could be clearly distinguished based on the simulation parameters. Taken the results together, it becomes apparent that it may be most advisable to perform a single somersault with a larger moment of inertia when achieving the tucked position, a longer duration to achieve the tucked position, a longer duration of staying tucked, and an intermediate moment of inertia during landing. This strategy comprises the largest amount of movement options associated with an upright landing and thus the highest probability of success when performing a single somersault