<div>Polymer nanocomposites (PNC) have an excellent potential for in-situ strain sensing applications in static and dynamic loading scenarios. These PNCs have a polymer matrix of polyvinylidene fluoride (PVDF) with a conductive filler of multi-walled carbon nanotubes (MWCNT) and have both piezoelectric and piezoresistive characteristics. Generally, this composite would accurately measure either low-frequency dynamic strain using piezoresistive characteristic or high-frequency dynamic strains using piezoelectric characteristics of the MWCNT/PVDF film sensor. Thus, the frequency bands of the strain sensor are limited to either piezoresistive or piezoelectric ranges. In this study, a novel weighted fusion technique, called Piezoresistive/Piezoelectric Fusion (PPF), is proposed to combine both piezoresistive and piezoelectric characteristics to capture the wide frequency bands of strain measurements in real-time. This fuzzy logic (FL)-based method combines the salient features (i.e., piezoresistive and piezoelectric) of the nanocomposite sensor via reasonably accurate models to extend the frequency range over a wider band. The FL determines the weight of each signal based on the error between the estimated measurements and the actual measurements. These weights indicate the contribution of each signal to the final fused measurement. The Fuzzy Inference System (FIS) was developed using both optimization and data clustering techniques. In addition, a type-2 FIS was utilized to overcome the model’s uncertainty limitations. The developed PPF methods were verified with experimental data at different dynamic frequencies that were obtained from existing literature. The fused measurements of the MWCNT/PVDF were found to correlate very well with the actual strain, and a high degree of accuracy was achieved by the subtractive clustering PPF’s FISs algorithm. <br></div><div><br></div><div>3D force sensors have proven their effectiveness and relevance for robotics applications. They have also been used in medical and physical therapy applications such as surgical robots and Instrument Assisted Soft Tissue Manipulation (IASTM). The 3D force sensors have been utilized in robot-assisted surgeries and modern physical therapy devices to monitor the 3D forces for improved performances. The 3D force sensor performance and specifications depend on different design parameters, such as the structural configuration, placement of the sensing elements, and load criterion. In this work, different bioinspired structure configurations have been investigated and analyzed to obtain the optimal 3D force sensor configuration in terms of structural integrity, compactness, the safety factor, and strain sensitivity. A Finite Element Analysis (FEA) simulation was used for the analysis to minimize the time of the development cycle.</div><div><br></div><div><br></div><div>A tree branch design was used as the 3D force sensor’s elastic structure. The structure was made of aluminum with a laser-cutting fabrication process. The PVDF/MWCNT films contained piezoresistive and piezoelectric characteristics that allowed for static/low strain measurements and dynamic strain measurements, respectively. Two compositions with 0.1 wt.% and 2 wt.% PVDF/MWCNT sensing elements were selected for piezoelectric and piezoresistive strain measurements, respectively. These characteristic measurements were investigated under different vibration rates in a supported beam experiment. The 3D force sensor was tested under dynamic excitation in the Z-direction and the X-direction. A Direct Piezoresistive/Piezoelectric Fusion (DPPF) method was developed by fusing the piezoresistive and piezoelectric measurements at a given frequency that overcomes the limited frequency ranges of each of the strain sensor characteristics. The DPPF method is based on a fuzzy inference system (FIS) which is constructed and tuned using the subtractive clustering technique. Different nonlinear Hammerstein-Wiener (nlhw) models were used to estimate the actual strain from piezoresistive and piezoelectric measurements at the 3D force sensor. The DPPF method was tested and validated for different strain signal types using presumed Triangle and Square signal waves data. The DPPF has proven its effectiveness in fusing piezoresistive and piezoelectric measurements with different types of signals. In addition, an Extended Direct Piezoresistive/Piezoelectric Fusion (EPPF) is introduced to enhance the DPPF method and perform the fusion in a range of frequencies instead of a particular one. The DPPF and EPPF methods were implemented on the 3D force sensor data, and the developed fusion algorithms were tested on the proposed 3D force sensor experimental data. The simulation results show that the proposed fusion methods have been effective in achieving lower Root Mean Square Error (RMSE) than those obtained from the tuned nlhw models at different operating frequencies.</div>

<p dir="ltr">Individuals with typical audiometric sensitivity exhibit varying speech perception abilities in noisy environments, which may decline with age. Temporal processing plays a pivotal role in speech perception, especially in challenging listening conditions. Auditory decline due to aging involves both peripheral pathology and central auditory system changes, impacting temporal processing. To delineate the contributions of these changes, measurements of within- and across-channel temporal processing were conducted in a wide age range of normal-hearing individuals. Robust perception of within-channel temporal cues requires precise coding at both peripheral and central auditory pathway levels, while cross-channel processing relies on central mechanisms. Comprehensive data collection involved behavioral and electrophysiological measures, revealing age-related increases in behavioral thresholds, less robust cortical responses to gaps and temporal-coherence changes, and declining SPIN performance. Cross-channel measures proved to be more predictive of speech perception outcomes, emphasizing the significance of central auditory changes in age-related perceptual deficits.</p><p dir="ltr">A mini-EEG cap to record cortical EEG auditory responses to gaps in chinchillas using a new sedation protocol was validated. This advancement enhances translational potential and paves the way for exploring cortical auditory processing using complex stimuli in animal models. By facilitating simultaneous exploration of both subcortical and cortical consequences of auditory system pathologies, this development contributes to a more comprehensive understanding of auditory processes across species.</p>

Human temporal bone specimens are used in experiments measuring the sound transfer of the middle ear, which is the standard method used in the development of active and passive middle ear implants. Statistical analyses of these experiments usually require that the TB samples are representative of the population of non-pathological middle ears. Specifically, this means that the specimens must be mechanically well-characterized. We present an in-depth statistical analysis of 478 data sets of middle ear transfer functions (METFs) from different laboratories. The data sets are preprocessed and various contributions to the variance of the data are evaluated. We then derive a statistical range as a reference against which individual METF measurements may be validated. The range is calculated as the two-sided 95% tolerance interval at audiological frequencies. In addition, the mean and 95% confidence interval of the mean are given as references for assessing the validity of a sample group. Finally, we provide a suggested procedure for measuring METFs using the methods described herein.

<p dir="ltr">The present work expands the state of the art in the design of soft actuators and flexible sensors manufactured through fused deposition modelling (FDM) and direct ink writing (DIW). The first design consisted of flexible sensors for rehabilitation. Three different designs were tested and compared according to their sensitivity and accuracy. The flexible sensor successfully responded to deformation by changing its resistance. The first design of soft actuator was the Closed Dual Pneumatic Bellow Actuator. The soft actuator was manufactured using FDM and included an inner chamber in which the input air flows through and produces the actuation. The actuator also included dielectric electroactive polymer (DEAP) that showed response to pressure between the actuator and the object to be grasped. The electrodes of the DEAP were manufactured using commercial conductive TPU. A second soft actuator was designed with a circular shape and embedded DEAP. The electrodes in the DEAP consisted of conductive carbon grease. Previous tests were performed to assess the functionality of a DEAP structure using conductive carbon grease. The DEAP showed an increase in capacitance as pressure was applied on one side of the structure parallel to the electrodes and computational simulations validated such response. Future work using the sensors and actuators presented includes the implementation of a closed-loop system to the soft actuators, using the readouts of the sensors to adjust the input pressure and apply precise pressure on objects. The flexible sensor for rehabilitation has the potential to be implemented in each of the fingers of the hand and use the data to characterize the movement of the hand under different configurations providing feedback to patients in task-oriented therapy.</p>

Made available in DSpace on 2014-06-11T19:30:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-10-27Bitstream added on 2014-06-13T20:00:59Z : No. of bitstreams: 1 lopes_ag_dr_rcla.pdf: 2903807 bytes, checksum: 228b34baf835343d3246b38b7c81d87c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O envelhecimento, associado ao sedentarismo vem acompanhado de muitas alterações estruturais, funcionais e comportamentais. O controle postural depende da integridade dos sistemas sensoriais e motor e, portanto, as deteriorações que ocorrem nestes sistemas com a ausência de um estilo de vida saudável, podem influenciar o desempenho de controle postural. Entretanto, ainda não estão claras quais alterações funcionais nos sistemas sensoriais e motor podem ser promovidas pela pratica de exercícios físicos, bem como a relação entre estas alterações e as mudanças no desempenho de controle postural de adultos idosos. Assim, o objetivo deste estudo foi examinar os efeitos de um programa de atividade física no controle postural e componentes de capacidade funcional de idosos, abordando aspectos sensoriais, motores e o relacionamento entre ambos. Treze adultos idosos com idade entre 60 e 70 anos foram submetidos a avaliações sensoriais, motoras, de controle postural e capacidade funcional antes e após a participação em um programa de exercícios físicos generalizado. As avaliações sensoriais foram compostas por avaliação visual (acuidade e sensibilidade ao contraste) e somatossensorial (sensibilidade cutânea e sensibilidade ao movimento passivo). As avaliações motoras consistiram de medidas de torque articular e de latência de ativação muscular após perturbação da superfície de suporte. As avaliações de controle postural consistiram de medidas de oscilação corporal durante manutenção da postura ereta (em semitandem stance) e para capacidade funcional foi aplicada a bateria da AAHPERD, Os resultados indicaram que o programa de exercícios proposto influenciou positivamente as capacidades de agilidade, força e capacidade aeróbia e, ainda, a capacidade de produzir torque e latência muscular. Estes resultados indicam que o aumento causado na força muscular... / Aging and a sedentary life style exhibit several structural, functional and behavioral changes. A good postural control performance depends on the integrity of the sensory and motor systems, deterioration of these systems occurring with aging could influence the postural control performance, specifically in older adults that are more susceptible to falls. However, it is still unclear which sensory and motor functional changes can be affected by a physical fitness program, neither the relationship between these changes and the changes of the performance of postural control in older adults. Therefore, the purpose of this study was to examine the effects of a exercise training program in the performance of the sensory and motor systems and postural control in older adults and to investigate the relationship between changes in these systems and postural control in this population. Thirteen older adults with age from 60 to 70 years old were submitted to sensory, motor and postural control assessments. Sensory assessments were composed of visual (acuity and contrast sensitivity) and somatosensory assessments (tactile sensitivity of and sensitivity to passive motion). Motor assessments consisted of measurements of joint torque and muscular activity latency after displacement of support surface. Postural control assessments consisted of measuring the body oscillation during maintenance of the upright stance (semi-tandem stance) and de functional capacity where measured by the Functional fitness tests of AAHPERD. The results indicated that the training program improved de agility, strength and aerobic capacity of the functional capacity, the torque capacity and a reduction of the muscular latency. The absence of training effects on the postural control can indicate that the processing of sensory information can be more weight on de stand stance than the physical capabilities. The present study shows...(Complete abstract click electronic access below)

<div> <div> <div> <p> </p><div> <div> <div> <div> <div> <div> <p> </p><div> <div> <div> <p>Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) and transition metal carbides/nitrides (MXenes), have been recently receiving attention for gas sensing applications due to their high specific area and rich surface functionalities. However, using pristine 2D materials for gas-sensing applications presents some drawbacks, including high operation temperatures, low gas response, and poor selectivity, limiting their practical sensing applications. Moreover, one of the long-standing challenges of MXenes is their poor stability against hydration and oxidation in a humid environment, which negatively influences their long- term storage and applications. Many studies have reported that the sensitivity and selectivity of 2D materials can be improved by surface functionalization and hybridization with other materials.</p><p>In this work, the effects of surface functionalization and/or hybridization of these two materials classes (TMDCs and MXenes) on their gas sensing performance have been investigated. In one of the lines of research, 2D MoS2 nanoflakes were functionalized with Au nanoparticles as a sensing material, providing a performance enhancement towards sensing of volatile organic compounds (VOCs) at room temperature. Next, a nanocomposite film composed of exfoliated MoS2, single-walled carbon nanotubes, and Cu(I)−tris(mercaptoimidazolyl)borate complexes was the sensing material used for the design of a chemiresistive sensor for the selective detection of ethylene (C2H4). Moreover, the hybridization of MXene (Ti3C2Tx) and TMDC (WSe2) as gas-sensing materials was also proposed. The Ti3C2Tx/WSe2 hybrid sensor reveals high sensitivity, good selectivity, low noise level, and ultrafast response/recovery times for the detection of various VOCs. Lastly, we demonstrated a surface functionalization strategy for Ti3C2Tx with fluoroalkylsilane (FOTS) molecules, providing a superhydrophobic surface, mechanical/environmental stability, and excellent sensing performance. The strategies presented here can be an effective solution for not only improving materials' stability, but also enhancing sensor performance, shedding light on the development of next-generation field-deployable sensors.</p> </div> </div> </div><div><div><div><div><div><div> </div> </div> </div> </div> </div> </div></div></div></div> </div> </div> </div></div></div></div><div><div><div> </div> </div> </div>

<p>Sudden unexpected death in epilepsy (SUDEP) is a fatal complication of epilepsy that kills 1̃2 of every 10,000 epileptic patients every year. SUDEP has proven difficult to study because it frequently occurs unobserved and cannot be predicted. What limited clinical data exists suggests that SUDEP occurs as a cardiorespiratory collapse immediately following a seizure. In this work, I explore how a group of autonomic reflexes termed collectively as “oxygen‐conserving reflexes (OCRs)” lead to sudden death when activated during seizures. I also demonstrate multiple physiological parallels between the OCR‐mediated deaths that I report and the clinical data on cases of human SUDEP. Additionally, I explore the neural pathway underlying OCRs, identify the carotid body as a potential target for intervention, and demonstrate the efficacy of electroceutical intervention in reducing the mortality risk of OCR activation during seizures. This work seeks to both offer a neural explanation for SUDEP as well as present a promising target and means for potential intervention.</p>