Acoustic characterization of Hofstadter butterfly with resonant scatterers

We are interested in the experimental characterization of the Hofstadter butterfly by means of acoustical waves. The transmission of an acoustic pulse through an array of 60 variable and resonant scatterers periodically distribued along a waveguide is studied. An arbitrary scattering arrangement is realized by using the variable length of each resonator cavity. For a periodic modulation, the structures of forbidden bands of the transmission reproduce the Hofstadter butterfly. We compare experimental, analytical, and computational realizations of the Hofstadter butterfly and we show the influence of the resonances of the scatterers on the structure of the butterfly

Nonlocal boundary conditions for corrugated acoustic metasurface with strong near field interactions

The propagation of long-wavelength sound in the presence of a metasurface made by arranging acoustic resonators periodically upon or slightly above an impervious substrate is studied. The method of two-scale asymptotic homogenization is used to derive effective boundary conditions, which account for both the surface corrugation and the low-frequency resonance. This method is applied to periodic arrays of resonators of any shape operating in the long-wavelength regime. The approach relies on the existence of a locally periodic boundary layer developed in the vicinity of the metasurface, where strong near-field interactions of the resonators with each other and with the substrate take place. These local effects give rise to an effective surface admittance supplemented by nonlocal contributions from the simple and double gradients of the pressure at the surface. These phenomena are illustrated for the periodic array of cylindrical Helmholtz resonators with an extended inner duct. Effects of the centre-to-centre spacing and orientation of the resonators' opening on the nonlocality and apparent resonance frequency are studied. The model could be used to design metasurfaces with specific effective boundary conditions required for particular applications

A theory-based intervention to promote medication adherence in patients with rheumatoid arthritis: a randomized controlled trial

Introduction/objectives: Adherence to prescribed medication regimens is fundamental to the improvement and maintenance of the health of patients with rheumatoid arthritis. It is therefore important that interventions are developed to address this important health behavior issue. The aim of the present study was to design and evaluate a theory-based intervention to improve the medication adherence (primary outcome) among rheumatoid arthritis patients. Methods: The study adopted a pre-registered randomized controlled trial design. Rheumatoid arthritis patients were recruited from two University teaching hospitals in Qazvin, Iran from June 2018 to May 2019 and randomly assigned to either an intervention group (n = 100) or a treatment-as-usual group (n = 100). The intervention group received a theory-based intervention designed based on the theoretical underpinnings of the health action process approach (HAPA). More specifically, action planning (making detailed plans to follow medication regimen), coping planning (constructing plans to overcome potential obstacles that may arise in medication adherence), and self-monitoring (using a calendar to record medication adherence) of the HAPA has been used for the treatment. The treatment-as-usual group received standard care. Results: Data analysis was conducted based on the principle of intention to treat. Using a linear mixed-effects model (adjusted for age, sex, medication prescribed, and body mass index), the results showed improved medication adherence scores in the intervention group (loss to follow-up = 16) compared to the treatment-as-usual group (loss to follow-up = 12) at the 3-month (coefficient = 3.9; SE = 0.8) and 6-month (coefficient = 4.5; SE = 0.8) follow-up. Intervention effects on medication adherence scores were found to be mediated by some of the theory-based HAPA variables that guided the study. Conclusion: The results of the present study support the use of a theory-based intervention for improving medication adherence among rheumatoid arthritis patients, a group at-risk of not adhering to medication regimens

Study on the sound absorption behavior of multi-component polyester nonwovens: experimental and numerical methods

This study presents an investigation of the acoustical properties of multi-component polyester nonwovens with experimental and numerical methods. Fifteen types of nonwoven samples made with staple, hollow and bi-component polyester fibers were chosen to carry out this study. The AFD300 AcoustiFlow device was employed to measure airflow resistivity. Several models were grouped in theoretical and empirical model categories and used to predict the airflow resistivity. A simple empirical model based on fiber diameter and fabric bulk density was obtained through the power-fitting method. The difference between measured and predicted airflow resistivity was analyzed. The surface impedance and sound absorption coefficient were determined by using a 45 mm Materiacustica impedance tube. Some widely used impedance models were used to predict the acoustical properties. A comparison between measured and predicted values was carried out to determine the most accurate model for multi-component polyester nonwovens. The results show that one of the Tarnow model provides the closest prediction to the measured value, with an error of 12%. The proposed power-fitted empirical model exhibits a very small error of 6.8%. It is shown that the Delany–Bazley and Miki models can accurately predict surface impedance of multi-component polyester nonwovens, but the Komatsu model is less accurate, especially at the low-frequency range. The results indicate that the Miki model is the most accurate method to predict the sound absorption coefficient, with a mean error of 8.39%

Auditory mechanics in a bush-cricket: direct evidence of dual sound inputs in the pressure difference receiver

The ear of the bush-cricket Copiphora gorgonensis consists of a system of paired eardrums (tympana) on each foreleg. In these insects, the ear is backed by an air-filled tube, the acoustic trachea (AT), which transfers sound from the prothoracic acoustic spiracle to the internal side of the eardrums. Both surfaces of the eardrums of this auditory system are exposed to sound, making it a directionally sensitive pressure-difference receiver. A key feature of the AT is its capacity to reduce the velocity of sound propagation and alter the acoustic driving forces at the tympanum. The mechanism responsible for reduction in sound velocity in the AT remains elusive, yet it is deemed to depend on adiabatic or isothermal conditions. To investigate the biophysics of such multiple input ears, we used micro-scanning laser Doppler vibrometry and micro-computed X-ray tomography. We measured the velocity of sound propagation in the acoustic trachea, the transmission gains across auditory frequencies, and the time-resolved mechanical dynamics of the tympanal membranes in Copiphora gorgonensis. Tracheal sound transmission generates a gain of ~15 dB SPL, and a propagation velocity of ca. 255 m/s, a ~25% reduction from free field propagation. Modelling tracheal acoustic behaviour that accounts for thermal and viscous effects, we conclude that reduction in sound velocity within the acoustic trachea can be explained, amongst 34 others, by heat exchange between the sound wave and the tracheal walls

Implementing medication adherence interventions in four Dutch living labs; context matters

BACKGROUND: Despite the abundant availability of effective medication adherence interventions, uptake of these interventions into routine care often lacks. Examples of effective medication adherence interventions include telephone counseling, consult preparation and the teach-back method. Assessing context is an important step in understanding implementation success of interventions, but context is often not reported or only moderately described. This study aims to describe context-specific characteristics in four living labs prior to the implementation of evidence-based interventions aiming to improve medication adherence. METHODS: A qualitative study was conducted within four living labs using individual interviews (n = 12) and focus groups (n = 4) with project leaders and involved healthcare providers. The four living labs are multidisciplinary collaboratives that are early adopters of medication adherence interventions in the Dutch primary care system. Context is defined as the environment or setting in which the proposed change is to be implemented. Interview topics to assess context were formulated based on the 'inner setting' and 'outer setting' domains of the Consolidated Framework for Implementation Research (CFIR). Interviews were recorded and transcribed verbatim. Transcripts were deductively analyzed. RESULTS: A total of 39 community pharmacists, pharmacy technicians, general practitioners and a home care employee participated in the (focus group) interviews. All four living labs proved to be pharmacy-driven and characterized by a high regard for innovation by staff members, a positive implementation climate, high levels of leadership engagement and high compatibility between the living labs and the interventions. Two living labs were larger in size and characterized by more formal communication. Two living labs were characterized by higher levels of cosmopolitanism which resulted in more adaptable interventions. Worries about external policy, most notably lack of reimbursement for sustainment and upscaling of the interventions, were shared among all living labs. CONCLUSIONS: Contextual characteristics of four living labs that are early adopters of medication adherence interventions provide detailed examples of a positive implementation setting. These can be used to inform dissemination of medication adherence interventions in settings less experienced in implementing medication adherence interventions