Association of chronic conditions and physical multimorbidity with new-onset incontinence in a nationwide prospective cohort study of older adults ≥ 50 years in China.

BACKGROUND: The relationship between multimorbidity (i.e. ≥ 2 chronic conditions) and incontinence (i.e. urinary and/or faecal incontinence) is underexplored. This study investigated the association between multimorbidity and incident incontinence in Chinese adults aged ≥50 years. METHODS: Data from the 2011 and 2015 waves of the China Health and Retirement Longitudinal Study were used. The association between 12 chronic conditions, multimorbidity and new-onset incontinence was analysed using weighted logistic regression models. Mediation analysis was conducted to explore the potential mediators (self-reported health, subjective memory, depressive symptoms, disability, cognitive function, handgrip strength, mobility limitations, medications and frailty status) between multimorbidity and incontinence. FINDINGS: Among 9,986 individuals aged ≥50 years who were continent at baseline, 5.3% (n = 521) were newly incontinent 4 years later (incident cases). The risk of incident incontinence increased with physical multimorbidity (OR 2.04, 95% CI 1.62-2.57). Compared to no chronic condition, having 1, 2, 3 and ≥ 4 chronic conditions were associated with incident incontinence with OR (95% CI): 1.41 (1.01-1.97), 1.74 (1.24-2.44), 2.82 (1.93-4.12) and 3.99 (2.29-6.95), respectively. The association between multimorbidity and incontinence was mediated by self-reported health (41.2%), medications (26.6%), mobility limitations (20.9%), depressive symptoms (12.8%), disability (11.6%), subjective memory (8.7%) and frailty status (8.3%). CONCLUSION: This longitudinal study found that physical multimorbidity and specific chronic conditions may increase the risk of new-onset incontinence among Chinese adults aged ≥50 years. Self-reported health, medications and mobility limitations seemed to be important intermediate conditions between multimorbidity and incident incontinence.

Association of smoking status and nicotine dependence with multi-morbidity in China: A nationally representative crosssectional study.

INTRODUCTION: Multi-morbidity is a public health priority as it is associated with an increased risk of mortality and a substantial healthcare burden. Smoking is considered a predisposing factor for multi-morbidity, but evidence for an association between multi-morbidity and nicotine dependence is insufficient. This study aimed to explore the association between smoking status, nicotine dependence, and multi-morbidity in China. METHODS: We recruited 11031 Chinese citizens from 31 provinces in 2021 using a multistage stratified cluster sampling strategy to ensure the study population represented national population characteristics. The association between smoking status and multi-morbidity was analyzed using binary logistic regression and multinomial logit regression models. We then analyzed the associations between four kinds of smoking status (age at smoking initiation, cigarette consumption per day, smoking when ill in bed, and inability to control smoking in public places), nicotine dependence, and multi-morbidity among participants who were current smokers. RESULTS: Compared with non-smokers, the odds of multi-morbidity were higher among ex-smokers (adjusted odd ratio, AOR=1.40, 95% CI: 1.07-1.85). The risk of multi-morbidity was greater in participants who were underweight/overweight/obese (AOR=1.90; 95% CI: 1.60-2.26) compared with those who were normal weight. and also greater for drinkers (AOR=1.34; 95% CI: 1.09-1.63) than non-drinkers. Compared with children who began smoking at the age of <15 years, participants aged >18 years had a lower likelihood of multi-morbidity (AOR=0.52; 95% CI: 0.32-0.83). People who consumed ≥31 cigarettes per day (AOR=3.77; 95% CI: 1.47-9.68) and those who smoked when ill in bed (AOR=1.70; 95% CI: 1.10-2.64) were more likely to have multi-morbidity. CONCLUSIONS: Our findings show that smoking behavior, including initiation age, frequency of daily smoking, and still smoking during illness or in public, is a critical risk factor for multi-morbidity, especially when combined with alcohol consumption, physical inactivity, and abnormal weight (underweight, overweight, or obese). This highlights the crucial effect of smoking cessation in the prevention and control of multi-morbidity, especially in patients with three or more diseases. Implementing smoking and lifestyle interventions to promote health would both benefit adults and prevent the next generation from initiating habits that increase the risk of multi-morbidity.

The Bidirectional Association Between Cognitive Function and Gait Speed in Chinese Older Adults: Longitudinal Observational Study.

BACKGROUND: Cognitive and gait speed decline are common conditions in older adults and are often associated with future adverse consequences. Although an association between cognitive function and gait speed has been demonstrated, its temporal sequence remains unclear, especially in older Chinese adults. Clarifying this could help identify interventions to improve public health in older adults. OBJECTIVE: This study aims to examine the longitudinal reciprocal association between gait speed and cognitive function and the possible temporal sequence of changes in both factors in a national longitudinal cohort. METHODS: Data were derived from 2 waves (2011 baseline and 2015 follow-up) of the China Health and Retirement Longitudinal Study (CHARLS). Participants 60 years or older, without dementia or Parkinson disease at baseline, and with completed data on gait speed and cognition at both baseline and follow-up were included. Usual gait speed was measured over two 2.5-m walks. Mental intactness and episodic memory were used to assess global cognitive function. Cross-lagged panel models and linear mixed-effects models were used to examine the association between cognition and gait speed over time. Standardized coefficients were reported. RESULTS: A total of 3009 participants (mean age 66.4 years, SD 5.4 years; 1422/3009, 47.26%, female participants) were eligible for inclusion in our analyses. Cross-lagged panel analyses revealed that after accounting for baseline gait speed, cognition, and potential confounders, baseline global cognition (ß=.117, 95% CI 0.082-0.152; P<.001), mental intactness (ß=.082, 95% CI 0.047-0.118; P<.001), and episodic memory (ß=.102, 95% CI 0.067-0.137; P<.001) were associated with subsequent gait speed. Simultaneously, baseline gait speed was also associated with subsequent global cognition (ß=.056, 95% CI 0.024-0.087; P=.001), mental intactness (ß=.039, 95% CI 0.008-0.069; P=.01), and episodic memory (ß=.057, 95% CI 0.023-0.092; P=.001). The comparison of standardized cross-lagged coefficients suggested that the effect size of baseline global cognition on subsequent gait speed was significantly larger than the reverse effect (χ12=6.50, P for difference=.01). However, the effects of both mental intactness and episodic memory on subsequent gait speed were not significantly stronger than those of the reverse pathway (χ12=3.33, P for difference=.07 and χ12=3.21, P for difference=.07). Linear mixed-effects analyses further supported these bidirectional relationships, revealing that lower baseline cognitive scores predicted steeper declines in gait speed trajectory, and slower baseline gait speed predicted more declines in cognitive trajectory over time. CONCLUSIONS: There is a longitudinal bidirectional association between usual gait speed and both global cognitive function and specific domains of mental intactness and episodic memory among Chinese older adults. Baseline global cognition is likely to have a stronger association with subsequent gait speed than the reverse pathway. This interlinkage is noteworthy and may have implications for public health. Maintaining normal cognitive function may be an important interventional strategy for mitigating age-related gait speed reduction.

Tunable acoustic metasurface based on tunable piezoelectric composite structure.

Due to the potential engineering needs, the passive tunable metasurfaces with a high performance equivalent to the active phased array is worthy of research. Here, a passive ultrathin metasurface unit composed of a piezoelectric composite structure (PCS) connected to an external capacitor, which can modulate the phase of the transmitted acoustic waves at a deep subwavelength scale only by controlling the external capacitor but without changing the structure, is proposed. Then, a tunable acoustic metasurface composed of 20 identical PCSs is introduced to realize three acoustic functions, beam steering, beam focusing, and tweezer-like beam generating, just by changing the external capacitors. The phase-control abilities of the PCS unit and three functions of the designed metasurface are proved both numerically and experimentally. This study provides the possibility to design ultrathin tunable acoustic metasurfaces with the ability of precise control and passive materials.

Acoustic waveguide with virtual soft boundary based on metamaterials.

The use of acoustic metamaterials with novel phenomena to design acoustic waveguides with special properties has obvious potential application value. Here, we propose a virtual soft boundary (VSB) model with high reflectivity and half cycle phase loss, which consists of an acoustic propagation layer and an acoustic metamaterial layer with tube arrays. Then the waveguide designed by the VSB is presented, and the numerical and experimental results show that it can separate acoustic waves at different frequencies without affecting the continuity and the flow of the medium in the space. The VSB waveguide can enrich the functions of acoustic waveguides and provide more application prospects.

Helical Higher-Order Topological States in an Acoustic Crystalline Insulator.

The topological states in quantum Hall insulators and quantum spin Hall insulators that emerge helical are considered nondissipative. However, in crystalline systems without spin-orbit couplings, the existing higher-order topological states are considered not helical, and the energy suffers from dissipation during propagation. In this work, by introducing the intrinsic pseudospin degree of freedom, we theoretically and experimentally present the existence of the helical higher-order topological states in the C_{6}-symmetric topological crystalline insulators based on the acoustic samples. Crucially, rather than considering the global interaction of the large bulk, we further intuitively reveal the impacts of the geometries of the crystal on the generation mechanisms and natural behaviors of these states based on the simple equivalent models. These results provide a versatile way for guiding the design of the desired topological materials.

Three-dimensional broadband acoustic illusion cloak for sound-hard boundaries of curved geometry.

Acoustic illusion cloaks that create illusion effects by changing the scattered wave have many potential applications in a variety of scenarios. However, the experimental realization of generating three-dimensional (3D) acoustic illusions under detection of broadband signals still remains challenging despite the paramount importance for practical applications. Here we report the design and experimental demonstration of a 3D broadband cloak that can effectively manipulate the scattered field to generate the desired illusion effect near curved boundaries. The designed cloak simply comprises positive-index anisotropic materials, with parameters completely independent of either the cloaked object or the boundary. With the ability of manipulating the scattered field in 3D space and flexibility of applying to arbitrary geometries, our method may take a major step toward the real world application of acoustic cloaks and offer the possibilities of building advanced acoustic devices with versatile functionalities.

Acoustic one-way metasurfaces: Asymmetric Phase Modulation of Sound by Subwavelength Layer.

We theoretically design and numerically demonstrate an acoustic one-way metasurface, which is a planar and acoustically subwavelength layer behaving like a nearly-reflectionless surface with arbitrary wave-steering capability for incident wave impinging on one side, while virtually blocking the reversed wave. The underlying mechanism is based on an asymmetric phase modulation by coupling a phase array and a near-zero-index medium. We exemplify a metastructure-based implementation by combining the hybrid metastuctures and labyrinthine structures. Moreover, the performance of the proposed implementation is demonstrated via three distinct phenomena of anomalous refraction, wave splitting and conversion of propagation wave to surface wave. Our findings may offer more possibilities for sound manipulation and improve the application potential of acoustic artificial devices in situations such as ultrasonic imaging and therapy.

Broadband non-reciprocal transmission of sound with invariant frequency.

We design and experimentally demonstrate a broadband yet compact acoustic diode (AD) by using an acoustic nonlinear material and a pair of gain and lossy materials. Due to the capabilities of maintaining the original frequency and high forward transmission while blocking backscattered wave, our design is closer to the desired features of a perfect AD and is promising to play the essential diode-like role in realistic acoustic systems, such as ultrasound imaging, noise control and nondestructive testing. Furthermore, our design enables improving the sensitivity and the robustness of device simultaneously by tailoring an individual structural parameter. We envision our design will take a significant step towards the realization of applicable acoustic one-way devices, and inspire the research of non-reciprocal wave manipulation in other fields.

Dispersionless Manipulation of Reflected Acoustic Wavefront by Subwavelength Corrugated Surface.

Free controls of optic/acoustic waves for bending, focusing or steering the energy of wavefronts are highly desirable in many practical scenarios. However, the dispersive nature of the existing metamaterials/metasurfaces for wavefront manipulation necessarily results in limited bandwidth. Here, we propose the concept of dispersionless wavefront manipulation and report a theoretical, numerical and experimental work on the design of a reflective surface capable of controlling the acoustic wavefront arbitrarily without bandwidth limitation. Analytical analysis predicts the possibility to completely eliminate the frequency dependence with a specific gradient surface which can be implemented by designing a subwavelength corrugated surface. Experimental and numerical results, well consistent with the theoretical predictions, have validated the proposed scheme by demonstrating a distinct phenomenon of extraordinary acoustic reflection within an ultra-broad band. For acquiring a deeper insight into the underlying physics, a simple physical model is developed which helps to interpret this extraordinary phenomenon and predict the upper cutoff frequency precisely. Generations of planar focusing and non-diffractive beam have also been exemplified. With the dispersionless wave-steering capability and deep discrete resolution, our designed structure may open new avenue to fully steer classical waves and offer design possibilities for broadband optical/acoustical devices.

Three-dimensional ultrathin planar lenses by acoustic metamaterials.

Acoustic lenses find applications in various areas ranging from ultrasound imaging to nondestructive testing. A compact-size and high-efficient planar acoustic lens is crucial to achieving miniaturization and integration, and should have deep implication for the acoustic field. However its realization remains challenging due to the trade-off between high refractive-index and impedance-mismatch. Here we have designed and experimentally realized the first ultrathin planar acoustic lens capable of steering the convergence of acoustic waves in three-dimensional space. A theoretical approach is developed to analytically describe the proposed metamaterial with hybrid labyrinthine units, which reveals the mechanism of coexistence of high refractive index and well-matched impedance. A hyperbolic gradient-index lens design is fabricated and characterized, which can enhance the acoustic energy by 15 dB at the focal point with very high transmission efficiency. Remarkably, the thickness of the lens is only approximately 1/6 of the operating wavelength. The lens can work within a certain frequency band for which the ratio between the bandwidth and the center frequency reaches 0.74. By tailoring the structure of the metamaterials, one can further reduce the thickness of the lens or even realize other acoustic functionalities, opening new opportunity for manipulation of low-frequency sounds with versatile potential.

Reflected wavefront manipulation based on ultrathin planar acoustic metasurfaces.

The introduction of metasurfaces has renewed the Snell's law and opened up new degrees of freedom to tailor the optical wavefront at will. Here, we theoretically demonstrate that the generalized Snell's law can be achieved for reflected acoustic waves based on ultrathin planar acoustic metasurfaces. The metasurfaces are constructed with eight units of a solid structure to provide discrete phase shifts covering the full 2π span with steps of π/4 by coiling up the space. By careful selection of the phase profiles in the transverse direction of the metasurfaces, some fascinating wavefront engineering phenomena are demonstrated, such as anomalous reflections, conversion of propagating waves into surface waves, planar aberration-free lens and nondiffracting Bessel beam generated by planar acoustic axicon. Our results could open up a new avenue for acoustic wavefront engineering and manipulations.

Acoustic illusion near boundaries of arbitrary curved geometry.

We have proposed a scheme and presented the first experimental demonstration of acoustic illusion, by using anisotropic metamaterials to manipulate the acoustic field near boundaries of arbitrary curved geometry. Numerical simulations and experimental results show that in the presence of an illusion cloak, any object can be acoustically transformed into another object. The designed illusion cloak simply comprises positive-index anisotropic materials whose material parameters are non-singular, homogeneous and, moreover, independent of the properties of either the original object or the boundary.

Acoustic cloaking by a superlens with single-negative materials.

We propose a specific transformation in cloaking to make an acoustic sensor undetectable, in which the cloaking shell consists of complementary media with single-negative acoustic parameters instead of double-negative ones, and is proved to be a magnifying superlens. Moreover, the acoustical parameters of the cloak are completely independent of those of the host material as well as the cloaked object. This may significantly facilitate the experimental realization of acoustic cloaks and is of fundamental importance in a wide range of acoustics, optics, and engineering applications.

Effective velocity of 2D phononic crystals with rectangular lattice.

The effective velocity of elastic waves for two-dimensional (2D) phononic crystals with rectangular lattice in the long-wavelength limit is studied by numerical simulations. It is demonstrated that, for all three propagating modes, not only the modes polarized in-plane (L wave and SV wave), but also the mode polarized out-plane (SH wave), the effective velocities are distinctly anisotropic and the slowness curves exhibit twofold symmetry. The anisotropy increases as the filling fraction increases or as the width to length ratio of the lattice decreases, and high anisotropy can be obtained in phononic crystals with large contrast between material parameters, which is much higher in rectangular lattice than in square lattice with the same material parameters. Owing to these dependences, the effective velocity can be controlled in engineering.

Band gaps of lamb waves in one-dimensional piezoelectric composite plates: effect of substrate and boundary conditions.

We theoretically study the band structures of Lamb waves in one-dimensional phononic crystal plates consisting of piezoelectric ceramics placed periodically in epoxy with epoxy or piezoelectric ceramic substrate by the virtual plane wave expansion method. The dependences of the widths and starting frequencies of first band gaps (FBG) on the substrate's thickness, the filling fraction, and the lattice spacing are calculated for different materials of substrate under different electric boundary conditions, i.e., short circuit (SC) and open circuit (OC). The FBG width decreases gradually as the substrate's thickness increases and the FBG starting frequency increases progressively as the thickness increases on the whole. The FBG widths and starting frequencies with SC are always larger than with OC. Our research shows that it is possible to control the width and starting frequency of the FBG in the engineering according to need by choosing suitable values of the substrate's thickness, the filling fraction, and the lattice spacing.

Effective medium method for sound propagation in a soft medium containing air bubbles.

An effective medium method (EMM) is developed to investigate the nonlinear propagation of acoustic waves for soft media containing air bubbles, which accounts for the effects of weak compressibility, viscosity, surrounding pressure, surface tension, and encapsulating shells. Based on the dynamics model of an individual bubble that has included these effects, the EMM is presented by employing a simple perturbation approach to "homogenize" the bubbly soft media. The equations describing the fundamental and the second harmonic waves are derived that applies to three-dimensional cases, and then solved in a one-dimensional case to obtain the effective acoustical parameters of a longitudinal wave. The EMM is compared with the previous theories in three representative cases regarded as simple models of significant practical applications. The results show that the EMM agrees well with the previous theories and can incorporate the additional effects, which may notably affect the accuracy of the results. The limitations of the EMM are also identified and stated.

Application of ultrasound in preparing pathological sections to reduce processing time.

It has been found experimentally that application of sub-mega and low megahertz ultrasound (US) of spatial and temporal averaged intensity /(sata) up to 10 W/cm(2) during the process of preparing pathological sections of the mouse tissue has shortened the processing time from 12h (without US) to less than half an hour (with US). The experiment has also showed that the processing time reached the shortest for ultrasound f=200 kHz among the frequencies of 200 kHz, 400 kHz, 600 kHz, 800 kHz and 1 MHz used in this study. It has been proposed that ultrasound inducing non-inertial cavitation enhanced the permeability of cell membrane to liquid. Thus tissue fixation and dehydration were speeded up by application of US.

The band gaps of plate-mode waves in one-dimensional piezoelectric composite plates: polarizations and boundary conditions.

Theoretical studies are presented for the band structures of plate-mode waves in a one-dimensional (1-D) phononic crystal plate consisting of piezoelectric ceramics placed periodically in an epoxy substrate. The dependences of the widths and starting frequencies of first band gaps (FBG) on the filling fraction and the thickness to lattice pitch ratio are calculated for different polarizations of piezoelectric ceramics under different electric boundary conditions, i.e., short circuit (SC) and open circuit (OC). We found that the FBG always is broadened by polarizing piezoelectric ceramics, and the FBG widths with SC always are larger than that with OC for the same polarization. Our research shows that there are three critical parameters which determine the FBG: the polarized directions, the filling fraction, and the ratio of the plate thickness to the lattice pitch, respectively. Therefore, we can control the width and starting frequency of the FBG in the engineering according to need by choosing these parameters of the system.