Deformation occurs in a thin liquid film when it is subjected to a non-uniform electric field, which is referred to as the electrohydrodynamic patterning. Due to the development of a non-uniform electrical force along the surface, the film would evolve into microstructures/nanostructures. In this work, a linear and a nonlinear model are proposed to thoroughly investigate the steady state (i.e. equilibrium state) of the electrohydrodynamic deformation of thin liquid film. It is found that the deformation is closely dependent on the electric Bond number BoE. Interestingly, when BoE is larger than a critical value, the film would be deformed remarkably and get in contact with the top template. To model the ‘contact’ between the liquid film and the solid template, the disjoining pressure is incorporated into the numerical model. From the nonlinear numerical model, a hysteresis deformation is revealed, i.e. the film may have different equilibrium states depending on whether the voltage is increased or decreased. To analyse the stability of these multiple equilibrium states, the Lyapunov functional is employed to characterise the system’s free energy. According to the Lyapunov functional analysis, at most three equilibrium states can be formed. Among them, one is stable, another is metastable and the third one is unstable. Finally, the model is extended to study the three-dimensional deformation of the electrohydrodynamic patterning.

As a novel type of catalytic Janus micromotor (JM), a double-bubble-powered Janus micromotor has a distinct propulsion mechanism that is closely associated with the bubble coalescence in viscous liquids and corresponding flow physics. Based on high-speed camera and microscopic observation, we provide the first experimental results of the coalescence of two microbubbles near a JM. By performing experiments with a wide range of Ohnesorge numbers, we identify a universal scaling law of bubble coalescence, which shows a cross-over at dimensionless time $\tilde{t}$ = 1 from an inertially limited viscous regime with linear scaling to an inertial regime with 1/2 scaling. Due to the confinement from the nearby solid JM, we observe asymmetric neck growth and find the combined effect of the surface tension and viscosity. The bubble coalescence and detachment can result in a high propulsion speed of ∼0.25 m s−1 for the JM. We further characterise two contributions to the JM’s displacement propelled by the coalescing bubble: the counteraction from the liquid due to bubble deformation and the momentum transfer during bubble detachment. Our findings provide a better understanding of the flow dynamics and transport mechanism in micro- and nano-scale devices like the swimming microrobot and bubble-powered microrocket.

A new fossil of Lycidae, Domipteron gaoi n. gen. n. sp., is described from Miocene Dominican amber. The fossil exhibits a combination of characteristics found in both Calopterini and Eurrhacini. To determine its systematic placement, we conducted phylogenetic analyses based on adult morphological features. Our analyses indicate that the new fossil belongs to Calopterini.

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The lift aerodynamic admittances of an airfoil at different angles of attack (AoAs) in turbulent flow are investigated using a combination of theoretical and experimental approaches. Two theoretical one-wavenumber aerodynamic admittances, namely the Sears and Atassi functions, are reviewed and uniformly normalized for comparison with experimental results. In theory, generalized aerodynamic admittances are generated by introducing the spanwise influence into one-wavenumber aerodynamic admittances. The influence of AoA on generalized aerodynamic admittance includes its effect on both the spanwise influence term and one-wavenumber aerodynamic admittances. The experiment indicates that prior to the prestall region, the increase in the spanwise influence factor correlates with the increase in AoA, with the growth rate of the spanwise influence factor likewise accelerating. The Atassi functions demonstrate that the influence of AoA on one-wavenumber aerodynamic admittances is based on the assumption of full correlation in the spanwise direction. Experimental results suggest that one-wavenumber aerodynamic admittances are inapplicable to actual turbulence; however, the Atassi function accurately represents experimental values at the corresponding AoA when taking into account the spanwise effects.

In this study, the propagation behaviour of detonation waves in a channel filled with stratified media is analysed using a detailed chemical reaction model. Two symmetrical layers of non-reactive gas are introduced near the upper and lower walls to encapsulate a stoichiometric premixed H2–air mixture. The effects of gas temperature and molecular weight of the non-reactive layers on the detonation wave’s propagation mode and velocity are examined thoroughly. The results reveal that as the non-reactive gas temperature increases, the detonation wave front transitions from a ‘convex’ to a ‘concave’ shape, accompanied by an increase in wave velocity. Notably, the concave wave front comprises detached shocks, oblique shocks and detonation waves, with the overall wave system propagating at a velocity exceeding the theoretical Chapman–Jouguet speed, indicating the emergence of a strong detonation wave. Furthermore, when the molecular weight of non-reactive layers varies, the results qualitatively align with those obtained from temperature variations. To elucidate the formation mechanism of different detonation wave front shapes, a dimensionless parameter $\eta$ (defined as a function of the specific heat ratio and sound speed) is proposed. This parameter unifies the effects of temperature and molecular weight, confirming that the specific heat ratio and sound speed of non-reactive layers are the primary factors governing the detonation wave propagation mode. Additionally, considering the effect of mixture inhomogeneity on the detonation reaction zone, the stream tube contraction theory is proposed, successfully explaining why strong detonation waves form in stratified mixtures. Numerical results show good agreement with theoretical predictions, validating the proposed model.

We study the long-time asymptotics for the solution of the modified Camassa–Holm (mCH) equation with step-like initial data.

\begin{align*} &m_{t}+\left (m\left (u^{2}-u_{x}^{2}\right )\right )_{x}=0, \quad m=u-u_{xx}, \\[3pt] & {u(x,0)=u_0(x)\to \left \{ \begin{array}{l@{\quad}l} 1/c_+, &\ x\to +\infty, \\[3pt] 1/c_-, &\ x\to -\infty, \end{array}\right .} \end{align*}

$c_+$

$c_-$

$(y,t)$

$(\xi, c)$

$c=c_+/c_-$

$\{ (\xi, c)\,:\, \xi \in \mathbb{R}, \ c\gt 0, \ \xi =y/t\}$

$u(y,t)$

$\mathcal{O}(t^{-2})$

$\mathcal{O}(t^{-1})$

Perceived intergenerational mobility profoundly influences individual attitudes and behaviour, carrying important implications for social stability and development. How do Chinese citizens perceive the intergenerational persistence of family advantages, and how do these perceptions compare with reality? This study conducts multiple randomized vignette experiments across two online surveys to assess public perceptions of correlations between various socio-economic indicators of parents and their children. Respondents estimate moderate to moderately strong correlations across generations. By leveraging the comparability of perceptions and objective estimates made possible by our novel measurement instrument, we find that respondents often overestimate the likelihood of equal opportunities for children from families with differing educational backgrounds. Alongside these largely optimistic perceptions, we also uncover signs of emerging pessimism. These results offer a nuanced snapshot of perceived social mobility in China, highlighting its multidimensional manifestations and divergence from reality, while also providing methodological insights for future research on its evolving dynamics.

Predicting healthcare costs for chronic diseases is challenging for actuaries, as these costs depend not only on traditional risk factors but also on patients’ self-perception and treatment behaviors. To address this complexity and the unobserved heterogeneity in cost data, we propose a dual-structured learning statistical framework that integrates covariate clustering into finite mixture of generalized linear models, effectively handling high-dimensional, sparse, and highly correlated covariates while capturing their effects on specific subgroups. Specifically, this framework is realized by imposing a penalty on the prior similarities among covariates, and we further propose an expectation-maximization-alternating direction method of multipliers (EM-ADMM) algorithm to address the complex optimization problem by combining EM with the ADMM. This paper validates the stability and effectiveness of the framework through simulation and empirical studies. The results show that our framework can leverage shared information among high-dimensional covariates to enhance fitting and prediction accuracy, while covariate clustering can also uncover the covariates’ network relationships, providing valuable insights into diabetic patients’ self-perception data.

Triceps skinfold thickness (TSF) is a surrogate marker of subcutaneous fat. Evidence is limited about the association of sex-specific TSF with the risk of all-cause mortality among maintenance hemodialysis (MHD) patients. We aimed to investigate the longitudinal relationship of TSF with all-cause mortality among MHD patients. A multicenter prospective cohort study was performed in 1034 patients undergoing MHD. The primary outcome was all-cause mortality. Multivariable Cox proportional hazards models were used to evaluate the association of TSF with the risk of mortality. The mean (standard deviation) age of the study population was 54.1 (15.1) years. 599 (57.9%) of the participants were male. The median (interquartile range) of TSF was 9.7 (6.3–13.3 mm) in males and 12.7 (10.0–18.0 mm) in females. Over a median follow up of 4.4 years (interquartile range, 2.4-7.9 years), there were 548 (53.0%) deaths. When TSF was assessed as sex-specific quartiles, compared with those in quartile 1, the adjusted HRs (95%CIs) of all-cause mortality in quartile 2, quartile 3 and quartile 4 were 0.93 (0.73, 1.19), 0.75 (0.58, 0.97) and 0.69 (0.52, 0.92), respectively (P for trend =0.005). Moreover, when analyzed by sex, increased TSF (≥9.7 mm for males and ≥18mm for females) was significantly associated with a reduced risk of all-cause mortality (quartile 3-4 vs. quartile 1-2; HR, 0.70; 95%CI: 0.55, 0.90 in males; quartile 4 vs. Quartile 1-3; HR, 0.69; 95%CI: 0.48, 1.00 in females). In conclusion, high TSF was significantly associated with lower risk of all-cause mortality in MHD patients.

We conducted a series of pore-scale numerical simulations on convective flow in porous media, with a fixed Schmidt number of 400 and a wide range of Rayleigh numbers. The porous media are modeled using regularly arranged square obstacles in a Rayleigh–Bénard (RB) system. As the Rayleigh number increases, the flow transitions from a Darcy-type regime to an RB-type regime, with the corresponding $Sh$–$Ra_D$ relationship shifting from sublinear scaling to the classical 0.3 scaling of RB convection. Here, $Sh$ and $Ra_D$ represent the Sherwood number and the Rayleigh–Darcy number, respectively. For different porosities, the transition begins at approximately $Ra_D = 4000$, at which point the characteristic horizontal scale of the flow field is comparable to the size of a single obstacle unit. When the thickness of the concentration boundary layer is less than approximately one-sixth of the pore spacing, the flow finally enters the RB regime. In the Darcy regime, the scaling exponent of $Sh$ and $Ra_D$ decreases as porosity increases. Based on the Grossman–Lohse theory (J. Fluid Mech. vol. 407, 2000, pp. 27–56; Phys. Rev. Lett. vol. 86, 2001, p. 3316), we provide an explanation for the scaling laws in each regime and highlight the significant impact of mechanical dispersion effects during the development of the plumes. Our findings provide some new insights into the validity range of the Darcy model.

This paper is focused on the existence and uniqueness of nonconstant steady states in a reaction–diffusion–ODE system, which models the predator–prey interaction with Holling-II functional response. Firstly, we aim to study the occurrence of regular stationary solutions through the application of bifurcation theory. Subsequently, by a generalized mountain pass lemma, we successfully demonstrate the existence of steady states with jump discontinuity. Furthermore, the structure of stationary solutions within a one-dimensional domain is investigated and a variety of steady-state solutions are built, which may exhibit monotonicity or symmetry. In the end, we create heterogeneous equilibrium states close to a constant equilibrium state using bifurcation theory and examine their stability.

This study delves into the intricate relationship between chief executive officers' (CEOs') experiences of poverty and the digital transformation of their firms. Employing comprehensive data collection on CEOs' birthplaces and leveraging advanced text analytics to quantify digitalization, our analysis encompasses a wide array of listed companies in China. The findings reveal that CEOs' impoverished experiences exert a detrimental influence on their firms' digital transformation efforts, primarily due to a lack of motivation and social resources necessary for such initiatives. However, this adverse effect can be ameliorated when CEOs gain access to substantial social resources in later life. Our conclusions are robust, supported by rigorous testing, and underscore not only the impact of CEOs' early-life poverty on corporate digitalization but also the potential for overcoming these challenges through the acquisition of external social resources and connections in adulthood. This study contributes significantly to existing literature and offers practical implications for enhancing corporate digital transformation strategies.

In response to the requirements for assessing the impact safety of aero-engines, a high-fidelity numerical simulation method based on overset mesh technology for six-degree-of-freedom rigid body motion is proposed. A gas-solid two-phase flow model is established, coupling two types of ice-debris (externally ingested ice and internally delaminated ice) with air, to analyse their behaviour in a dorsal S-shaped inlet with a diffusion ratio of 1.3. Results indicate that the ice-debris entering from the upper region of the entrance section exerts the most significant distortion on the total-pressure at the engine inlet. Additionally, the behaviour of ice-debris is determined by its angle with respect to the incoming flow direction and the shape of ice. Furthermore, although the ice-debris detached from the entrance section poses no immediate threat to the engine, the prolonged acceleration by high-speed airflow, with velocity increments exceeding 45 m/s, results in a higher kinetic energy carried upon impact with the inlet walls. Regarding externally ingested ice-debris, a smaller initial velocity corresponds to a higher probability of impacting the engine, accompanied by a significant increase in velocity. For instance, the irregular ice-debris ingested at an initial velocity of 6 m/s can experience velocity amplification exceeding 590%.

This paper presents detailed analyses of the Reynolds stresses and their budgets in temporally evolving stratified wakes using direct numerical simulation. Ensemble averaging is employed to mitigate statistical errors in the data, and the results are presented as functions of both the transverse and vertical coordinates – at time instants across the near-wake, non-equilibrium, and quasi-two-dimensional regimes for wakes in weakly and strongly stratified environments. Key findings include the identification of dominant terms in the Reynolds stress transport equations and their spatial structures, the generation and destruction processes of the Reynolds stresses, and the energy transfer between the Reynolds stress and the mean flow. The study also clarifies the effects of the Reynolds number and the Froude number. Additionally, we assess the validity of the eddy-viscosity type models and some existing closures for the Reynolds stress model, highlighting the limitations of isotropy and return-to-isotropy hypotheses in stratified flows.

Mapping reviews (MRs) are crucial for identifying research gaps and enhancing evidence utilization. Despite their increasing use in health and social sciences, inconsistencies persist in both their conceptualization and reporting. This study aims to clarify the conceptual framework and gather reporting items from existing guidance and methodological studies. A comprehensive search was conducted across nine databases and 11 institutional websites, including documents up to January 2024. A total of 68 documents were included, addressing 24 MR terms and 55 definitions, with 39 documents discussing distinctions and overlaps among these terms. From the documents included, 28 reporting items were identified, covering all the steps of the process. Seven documents mentioned reporting on the title, four on the abstract, and 14 on the background. Ten methods-related items appeared in 56 documents, with the median number of documents supporting each item being 34 (interquartile range [IQR]: 27, 39). Four results-related items were mentioned in 18 documents (median: 14.5, IQR: 11.5, 16), and four discussion-related items appeared in 25 documents (median: 5.5, IQR: 3, 13). There was very little guidance about reporting conclusions, acknowledgments, author contributions, declarations of interest, and funding sources. This study proposes a draft 28-item reporting checklist for MRs and has identified terminologies and concepts used to describe MRs. These findings will first be used to inform a Delphi consensus process to develop reporting guidelines for MRs. Additionally, the checklist and definitions could be used to guide researchers in reporting high-quality MRs.