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Ultrasonic communication and power transfer are attractive solutions when conventional electromagnetic-based or wired connections are unfeasible. Most ultrasonic communication applications concern a single-solid barrier. Nevertheless, some relevant scenarios can be composed of several fluid-solid media, through which communication and power transfer are intended. Due to its multi-layer nature, insertion loss and, consequently, the system efficiency considerably decrease. This paper presents an ultrasonic system capable of simultaneously power transferring and transmitting data through a set of two flat steel plates separated by a fluid layer using a pair of co-axially aligned piezoelectric transducers on opposite sides of the barrier. The system is based on frequency modulation and adopts a novel technique for automatic gain and automatic carrier control. The modems used herein were developed specifically for this application, rendering the system able to transfer data at a rate of 19,200 bps, using the frequency shift keying (FSK) modulation scheme and simultaneously transferring 66 mW of power through two flat steel plates (5 mm) separated by a fluid layer (100 mm), which completely supplied a pressure and temperature sensor. The proposed automatic gain control allowed a higher data transmission rate and the automatic carrier control reduced power consumption. The former reduced the transmission error from 12% to 5%, while the latter reduced the global power consumption from 2.6 W to 1.2 W. The proposed system is promising for monitoring applications such as oil wellbore structural health monitoring systems.

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Noise Radar technology is the general term used to describe radar systems that employ realizations of a given stochastic process as transmit waveforms. Originally, carriers modulated in amplitude by a Gaussian random signal, derived from a hardware noise source, were taken into consideration, justifying the adopted nomenclature. With the advances made in hardware as well as the rise of the software defined noise radar concept, waveform design emerges as an important research area related to such systems. The possibility of generating signals with varied stochastic properties increased the potential in achieving systems with enhanced performances. The characterization of random phase and frequency modulated waveforms (more suitable for several applications) has then gained considerable notoriety within the radar community as well. Several optimization algorithms have been proposed in order to conveniently shape both the autocorrelation function of the random samples that comprise the transmit signal, as well as their power spectrum density. Nevertheless, little attention has been driven to properly characterize the stochastic properties of those signals through closed form expressions, jeopardizing the effectiveness of the aforementioned algorithms as well as their reproducibility. Within this context, this paper investigates the performance of several random phase and frequency modulated waveforms, varying the stochastic properties of their modulating signals.

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Non-invasive Functional Electrical Stimulation (FES) is a technique applied for motor rehabilitation of patients with central nervous system injury. This technique requires programmable multichannel systems to configure the stimulation parameters (amplitude, frequency, and pulse width). Most FES systems are based on microcontrollers with fixed architecture; this limits the control of the parameters and the scaling to multiple channels. Although field programmable gate arrays (FPGA) have been used in FES systems as alternative to microcontrollers, most of them focus on signal acquisition, processing, or communication functions, or are for invasive stimulation. A few FES systems report using FPGAs for parameter configuration and pulse generation in non-invasive FES. However, generally they limit the value of the frequency or amplitude parameters to enable multichannel operation. This restricts free selection of parameters and implementation of modulation patterns, previously reported to delay FES-induced muscle fatigue. To overcome those limitations, this paper presents a proof-of-concept (technology readiness level three-TRL 3) regarding the technical feasibility and potential use of an FPGA-based pulse generator for non-invasive FES applications (PG-nFES). The main aims were: (1) the development of a flexible pulse generator for FES applications and (2) to perform a proof-of-concept of the system, comprising: electrical characterization of the stimulation parameters, and verification of its potential for upper limb FES applications. Biphasic stimulation pulses with high linearity (r 2 > 0.9998) and repeatability (>0.81) were achieved by combining the PG-nFES with a current-controlled output stage. Average percentage error in the characterizations was under 3% for amplitude (1-48 mA) and pulse width (20-400 µs), and 0% for frequency (10-150 Hz). A six-channel version of the PG-nFES was implemented to demonstrate the scalability feature. The independence of parameters was tested with three patterns of co-modulation of two parameters. Moreover, two complete FES channels were implemented and the claimed features of the PG-nFES were verified by performing upper limb functional movements involving the hand and the arm. Finally, the system enabled implementation of a stimulation pattern with co-modulation of frequency and pulse width, applied successfully for efficient elbow during repetitions of a functional movement.

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Neurons from several brain regions resonate in the theta frequency range (4-12 Hz), displaying a higher voltage response to oscillatory currents at a preferred 'resonant' frequency (fR). Subthreshold resonance could influence spiking and contribute to the selective entrainment of neurons during the network oscillatory activity that accompanies several cognitive processes. Neurons from different regions display resonance in specific theta subranges, suggesting a functional specialization. Further experimental work is needed to characterize this diversity and explore how frequency preference could be dynamically modulated. Theoretical studies have shown that the fine-tuning of resonance depends in a complex way on a variety of intrinsic factors and input properties, but their specific influence is difficult to dissect in cells. We performed slice electrophysiology, dynamic clamping and modelling to assess the differential frequency preference of rat entorhinal stellate neurons, hippocampal CA1 pyramidal neurons and cortical amygdala neurons, which share a hyperpolarization-activated current (Ih)-dependent resonance mechanism. We found heterogeneous resonance properties among the different types of theta-resonant neurons, as well as in each specific group. In all the neurons studied, fR inversely correlated with the effective input resistance (Rin), a measurable variable that depends on passive and active membrane features. We showed that resonance can be adjusted by manipulations mimicking naturally occurring processes, as the incorporation of a virtual constant conductance or cell depolarization, in a way that preserves the fR-Rin relationship. The modulation of frequency selectivity influences firing by shifting spike frequency and timing, which could influence neuronal communication in an active network.

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Behavior emerges from the interaction between the nervous system and peripheral devices. In the case of birdsong production, a delicate and fast control of several muscles is required to control the configuration of the syrinx (the avian vocal organ) and the respiratory system. In particular, the syringealis ventralis muscle is involved in the control of the tension of the vibrating labia and thus affects the frequency modulation of the sound. Nevertheless, the translation of the instructions (which are electrical in nature) into acoustical features is complex and involves nonlinear, dynamical processes. In this work, we present a model of the dynamics of the syringealis ventralis muscle and the labia, which allows calculating the frequency of the generated sound, using as input the electrical activity recorded in the muscle. In addition, the model provides a framework to interpret inter-syllabic activity and hints at the importance of the biomechanical dynamics in determining behavior.

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Objetivo: descrever e analisar o processo de adaptação e consistência de uso em sala de aula, do sistema de Frequência Modulada (FM) em crianças com deficiência auditiva, considerando a relevância do papel da família como intermediária entre o serviço e a escola. Método: Foi realizada entrega e adaptação do FM e explicações iniciais para pais, tais como: manuseio do dispositivo, duração da bateria e posicionamento do transmissor. No mesmo dia, os pais foram orientados a levar essas informações aos professores e foram agendados dois retornos. No primeiro foram realizadas avaliação de percepção de fala, aplicação do questionário socioeconômico e entrevista inicial com os pais, para obter informações que não constavam no prontuário; no segundo retorno, ocorreram o registro do uso diário do FM e a entrevista com pais para coletar informações quanto ao uso e dificuldades encontradas. Resultados: Observou-se equilíbrio quanto ao uso do FM. 43,9% utilizaram de forma consistente e 56,1% de forma inconsistente. Verificou-se que as crianças com perdas unilaterais tiveram tendência a menor utilização do FM. Não foi encontrada associação estatisticamente significativa no uso consistente do FM, quando comparado com as características da escola. A maioria dos pais relatou que os filhos estão fazendo uso do FM, no entanto, a média de horas não confirmou essa informação. Conclusão: Os achados deste estudo sugerem a necessidade de assistência aos pais na relação com os professores e na consistência de uso do sistema FM, a partir de relação formal estabelecida com a escola e o acompanhamento pelo fonoaudiólogo do serviço de saúde, que pode monitorar o uso do sistema na escola através de medidas diretas no transmissor.

Objective: describe and analyze the Frequency Modulation System (FM) adaptation process and its consistency of use in the classroom in children with hearing loss, taking into consideration family role relevance as an intermediary between the health service system and the school. Method: As part of the methodology a couple of steps were carried out: medical records analysis, FM adaptation and initial explanations to parents, such as device handling, battery lifetime and transmitter. At the same day, parents were asked to take this information to teachers and two returns were scheduled. At the first return, three activities were carried out: a speech perception evaluation, an initial interview with parents to obtain non-recorded information and the application of a socioeconomic questionnaire. The second return, when daily use of the FM system was registered by reading the transmitter record, and another interview with parents was performed, collecting information regarding the use and difficulties encountered. Results: 43.9% children used FM consistently and 56.1% inconsistently. Additionally, it was found that kids with unilateral losses tended to lower use of FM. There was no statistically significant association in the consistent use of FM when compared to the school characteristics. Most parents reported that their children were using FM, nevertheless, the average hours did not confirm this information. Conclusion: The findings of this study suggested that there should be greater teacher´s monitoring by parents together with an audiologist, who can verify the use of the FM system at the school through direct measurements on the transmitter.

Objetivo: Describir y analizar el proceso de adaptación y el uso de consistencia en el aula, el sistema de modulación de frecuencia (FM) en niños con pérdida auditiva, teniendo en cuenta la importancia del papel de la familia como intermediario entre el servicio y la escuela. Método: Se llevó a cabo la entrega y adaptación de FM y explicaciones iniciales a los padres, tales como: el manejo de dispositivos, duración de la batería y el posicionamiento del transmisor. El mismo día, los padres fueron instruidos para llevar esta información a los maestros y se imputaron dos vueltas. En la primera vuelta se realizó la evaluación de la percepción del habla, la aplicación del estudio socioeconómico y la entrevista inicial con los padres para obtener información no contenida en el registro. En la segunda vuelta, que se llevó a cabo la grabación de FM uso diario y las entrevistas con los padres, la recogida de información sobre el uso y las dificultades encontradas. Resultados: No hubo equilibrio en el uso de la FM. 43,9% utiliza constantemente y el 56,1% de manera inconsistente. Se encontró que los niños con pérdidas unilaterales tendían a un menor uso de FM. no hubo asociación estadísticamente significativa en el uso consistente de FM en comparación con las características de la escuela. La mayoría de los padres dicen que sus hijos están haciendo uso de FM, sin embargo, el número medio de horas ha no se ha confirmado esta información. Conclusión: Los resultados de este estudio sugieren que debería haber una mayor vigilancia de los padres con los maestros, y visualizar en el audiólogo, que puede controlar la utilización del sistema en la escuela a través de mediciones directas en el transmisor.

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A novel method for estimating the shear wave speed from crawling waves based on the amplitude modulation-frequency modulation model is proposed. Our method consists of a two-step approach for estimating the stiffness parameter at the central region of the material of interest. First, narrowband signals are isolated in the time dimension to recover the locally strongest component and to reject distortions from the ultrasound data. Then, the shear wave speed is computed by the dominant component analysis approach and its spatial instantaneous frequency is estimated by the discrete quasi-eigenfunction approximations method. Experimental results on phantoms with different compositions and operating frequencies show coherent speed estimations and accurate inclusion locations.

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OBJECTIVES: To evaluate both monaural and binaural processing skills in a group of children with autism spectrum disorder (ASD) and to determine the degree to which personal frequency modulation (radio transmission) (FM) listening systems could ameliorate their listening difficulties. STUDY DESIGN: Auditory temporal processing (amplitude modulation detection), spatial listening (integration of binaural difference cues), and functional hearing (speech perception in background noise) were evaluated in 20 children with ASD. Ten of these subsequently underwent a 6-week device trial in which they wore the FM system for up to 7 hours per day. RESULTS: Auditory temporal processing and spatial listening ability were poorer in subjects with ASD than in matched controls (temporal: P = .014 [95% CI -6.4 to -0.8 dB], spatial: P = .003 [1.0 to 4.4 dB]), and performance on both of these basic processing measures was correlated with speech perception ability (temporal: r = -0.44, P = .022; spatial: r = -0.50, P = .015). The provision of FM listening systems resulted in improved discrimination of speech in noise (P < .001 [11.6% to 21.7%]). Furthermore, both participant and teacher questionnaire data revealed device-related benefits across a range of evaluation categories including Effect of Background Noise (P = .036 [-60.7% to -2.8%]) and Ease of Communication (P = .019 [-40.1% to -5.0%]). Eight of the 10 participants who undertook the 6-week device trial remained consistent FM users at study completion. CONCLUSIONS: Sustained use of FM listening devices can enhance speech perception in noise, aid social interaction, and improve educational outcomes in children with ASD.

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