Perfect oblique-incidence ultrasound transmission across dissimilar solids

Perfect ultrasound transmission from one medium to another is critical in many applications, including medical treatment, imaging, and diagnostics. However, an obliquely incident ultrasonic wave through the solid-solid interface inevitably generates multiple wave modes (longitudinal waves and transverse waves). Accordingly, the well-known impedance matching theory considering only single wave mode fails to achieve the perfect oblique-incidence ultrasound transmission even from one isotropic solid to another. Here, we present the generalized matching theory that is newly established to enable the perfect transmission of ultrasonic waves across dissimilar solids at an arbitrary incidence angle and frequency. We also design a novel single-phase anisotropic solid-void metamaterial layer that can fulfill all conditions stated by the theory. It is shown that the insertion of the proposed metamaterial layer between metal (aluminum) and plastic (polyether ether ketone) plates achieves nearly perfect wave transmission over 98% energy efficiency, without which transmission reduces to 20%-40%. Our findings are validated numerically and experimentally

Generalized matching layers for perfect elastic-wave transmission

Consider a situation in which elastic waves are transmitted from an incident medium to a different target medium. When a longitudinal wave is obliquely incident at the solid-solid interface, both longitudinal and transverse waves are “partially” transmitted. Of course, unwanted reflections always occur as well. In this presentation, we introduce a new concept of a generalized matching layer that can “perfectly” transmit the target-mode (either longitudinal or transverse) elastic wave with 100% energy efficiency. By inserting the L-to-L or L-to-T matching layer between two dissimilar solids, mode-preserving (longitudinal-to-longitudinal) or mode-converting (longitudinal-to-transverse) perfect transmission can be successfully realized at the target incidence angle

Global Developments in Social Prescribing

Social prescribing is an approach that aims to improve health and well-being. It connects individuals to non-clinical services and supports that address social needs, such as those related to loneliness, housing instability and mental health. At the person level, social prescribing can give individuals the knowledge, skills, motivation and confidence to manage their own health and well-being. At the society level, it can facilitate greater collaboration across health, social, and community sectors to promote integrated care and move beyond the traditional biomedical model of health. While the term social prescribing was first popularised in the UK, this practice has become more prevalent and widely publicised internationally over the last decade. This paper aims to illuminate the ways social prescribing has been conceptualised and implemented across 17 countries in Europe, Asia, Australia and North America. We draw from the ‘Beyond the Building Blocks’ framework to describe the essential inputs for adopting social prescribing into policy and practice, related to service delivery; social determinants and household production of health; workforce; leadership and governance; financing, community organisations and societal partnerships; health technology; and information, learning and accountability. Cross-cutting lessons can inform country and regional efforts to tailor social prescribing models to best support local needs

Effect of a Digital Literacy Program on Older Adults’ Digital Social Behavior: A Quasi-Experimental Study

In South Korea, digital literacy education programs are expected to help its older population participate in online welfare services to increase their social support, self-esteem and well-being. This quasi-experimental study assesses the effects of digital literacy education on digital device usage among rural-dwelling adults aged 65 and above and evaluates the positive effects of digital literacy education on depression, happiness, quality of life, self-efficacy and cognitive function. A digital literacy education program and a customized questionnaire survey were conducted to evaluate smartphone use competency and the program’s effects, respectively. We also conducted a chi-square test, paired t-test and difference-in-differences regression analysis. The experimental group showed a significant increase in smartphone usage and video recording capacity than the control group. The happiness and cognitive function scores for dementia screening increased significantly by a mean of 3.7 and 1.1 points, respectively, after digital literacy education. Cognitive function increased significantly by 1.305 points in the experimental group compared to the control group (β = 1.305, p = 0.05 *). Digital literacy education for older adults in rural areas greatly increased smartphone use, video recording capacity, happiness and cognitive function. Based on these findings, it is recommended that the government should implement digital literacy education for older adults in rural areas to increase their happiness and cognitive function

Barriers and Enabling Factors Affecting Satisfaction and Safety Perception with Use of Bicycle Roads in Seoul, South Korea

Cycling has proven to be an important strategy in decreasing the risk of non-communicable diseases. This study aimed to discover barriers and enabling factors influencing satisfaction and safety perceptions towards the use of bicycle roads in the Seoul metropolitan area, South Korea. A cross-sectional survey of 190 youth and adult individuals was conducted. Sex, age, purpose of bicycle use, perceived safety, availability of facilities, road gradient, road width, and traffic on the bicycle road were associated with cycling regularity. Multivariate regression analysis showed that the sufficiency of bicycle parking space, moderate slope, and enough bicycle signs were significant enabling factors for satisfaction with the use of bicycle roads. Narrow bicycle roads were found to be a barrier to satisfaction with the use of bicycle roads. Moderate slope, enough bicycle signs, and enough maintenance facilities around bike roads were found to be enabling factors in the perceived safety of the use of bicycle roads, whereas traffic on the side of the bicycle road was found to be a barrier to perceived safety. Based on these findings, we conclude that healthy cities should promote cycling behavior encouraging enabling factors and initiating attempts to improve the factors that act as barriers through urban planning

Perfect circular polarization of elastic waves in solid media

Abstract Elastic waves involving mechanical particle motions of solid media can couple volumetric and shear deformations, making their manipulation more difficult than electromagnetic waves. Thereby, circularly polarized waves in the elastic regime have been little explored, unlike their counterparts in the electromagnetic regime, where their practical usage has been evidenced in various applications. Here, we explore generating perfect circular polarization of elastic waves in an isotropic solid medium. We devise a novel strategy for converting a linearly polarized wave into a circularly polarized wave by employing an anisotropic medium, which induces a so-far-unexplored coupled resonance phenomenon; it describes the simultaneous occurrence of the Fabry-Pérot resonance in one diagonal plane and the quarter-wave resonance in another diagonal plane orthogonal to the former with an exact 90° out-of-phase relation. We establish a theory explaining the involved physics and validate it numerically and experimentally. As a potential application of elastic circular polarization, we present simulation results demonstrating that a circularly polarized elastic wave can detect an arbitrarily oriented crack undetectable by a linearly polarized elastic wave

Transmodal Fabry-Pérot Resonance: Theory and Realization with Elastic Metamaterials

We discovered a new transmodal Fabry-Prot resonance where one elastic-wave mode is maximally transmitted to another. It occurs when the phase difference of two dissimilar modes through an anisotropic layer becomes odd multiples of pi under the reflection-free and weak mode-coupling assumptions. Unlike the well-established Fabry-Prot resonance, the transmodal resonance must involve two coupled elastic waves between longitudinal and shear modes. The investigation into the origin of wiggly transmodal transmission spectra suggests that efficient broadband mode conversion can be achieved if the media satisfy the structural stability condition to some degree. The new resonance mechanism, also experimentally characterized, opens up new possibilities for manipulating elastic wave modes as an effective alternative to generating shear-mode ultrasound