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We investigate the influence of rotation on the onset and saturation of the Faraday instability in a vertically oscillating two-layer miscible fluid using a theoretical model and direct numerical simulations (DNS). Our analytical approach utilizes Floquet analysis to solve a set of the Mathieu equations obtained from the linear stability analysis. The solution of the Mathieu equations comprises stable and harmonic, and subharmonic unstable regions in a three-dimensional stability diagram. We find that the Coriolis force delays the onset of the subharmonic instability responsible for the growth of the mixing zone size at lower forcing amplitudes. However, at higher forcing amplitudes, the flow is energetic enough to mitigate the instability delaying effect of rotation, and the evolution of the mixing zone size is similar in both rotating and non-rotating environments. These results are corroborated by DNS at different Coriolis frequencies and forcing amplitudes. We also observe that for $(\,f/\omega )^2<0.25$, where $f$ is the Coriolis frequency, and $\omega$ is the forcing frequency, the instability and the turbulent mixing zone size-$L$ saturates. When $(\,f/\omega )^2\geq 0.25$, the turbulent mixing zone size-$L$ never saturates and continues to grow.
Pericardial tamponade, which increases postoperative mortality and morbidity, is still not uncommon after paediatric cardiac surgery. We considered that posterior pericardiotomy may be a useful and safe technique in order to reduce the incidence of early and late pericardial tamponade. Herein, we present our experience with creation of posterior pericardial window following congenital cardiac surgical procedures.
Methods:
This retrospective study evaluated 229 patients who underwent paediatric cardiac surgical procedures between June 2021 and January 2023. A posterior pericardial window was created in all of the patients. In neonates and infants, pericardial window was performed at a size of 2x2 cm, whereas a 3x3 cm connection was established in elder children and young adults. A curved chest tube was placed and positioned at the posterolateral pericardiophrenic sinus. An additional straight anterior mediastinal chest tube was also inserted in every patient. Transthoracic echocardiographic evaluations were performed daily to assess postoperative pericardial effusion.
Results:
A total of 229 (135 male, 94 female) patients were operated. Mean age and body weight were 24.2 ± 26.7 months and 10.2 ± 6.7 kg, respectively. Eight (3.5%) of the patients were neonates where 109 (47.6%) were infants and 112 (48.9%) were in childhood. Fifty-two (22.7%) re-do operations were performed. Six (2.6%) patients underwent postoperative surgical re-exploration due to surgical site bleeding. Any early or late pericardial tamponade was not encountered in the study group.
Conclusions:
Posterior pericardial window is an effective and safe technique in order to prevent both the early and late pericardial tamponade after congenital cardiac surgery.
The present study revisits the differential roles of form, meaning, and use aspects of phonological vocabulary knowledge in L2 listening proficiency. A total of 126 Japanese English-as-a-foreign-language listeners completed the TOEIC Listening test, working memory and auditory processing tests, the Metacognitive Awareness Listening Questionnaire, and several tasks designed to tap into three broad aspects of phonological vocabulary knowledge: (1) the ability to access phonological forms without any orthographic cues (phonologization), (2) the ability to recognize words regardless of the talker (generalization), and (3) the ability to determine the semantic and collocational appropriateness of words in global contexts in a fast and stable manner (automatization). Whereas the perceptual, cognitive, and metacognitive variables made relatively small contributions to L2 listening proficiency (0.4%–21.3%), the vocabulary factors explained a large amount of the variance (77.6%) in the full regression model (R2 = .507). These large lexical effects uniquely derived from the three different aspects of phonological vocabulary knowledge—automatization (55.3%), phonologization (20.8%), and generalization (1.5%). The findings suggest that successful L2 listening skill acquisition draws on not only various levels of phonological form-meaning mapping (phonologization, generalization) but also the spontaneous and robust retrieval of such vocabulary knowledge in relation to surrounding words (automatization).
This paper proposes a dynamic model to capture the interaction among the environment, human capital accumulation, and economic growth. We emphasize the mechanism that pollution stock depresses human capital accumulation, which has received increasing support from empirical studies. The model predicts that the development of pollution-intensive industries can help an economy gear up a short-run prosperity, but it impairs the capability for long-run economic growth, trapping the economy at a low development level. The cost for a dirty economy to switch is expensive and even infeasible if the environmental degradation is irreversible. Policy interventions, such as tax on pollution and subsidy on human capital, can help alleviate but cannot eradicate the economic stagnation.
We introduce a projection-based model reduction method that systematically accounts for nonlinear interactions between the resolved and unresolved scales of the flow in a low-dimensional dynamical systems model. The proposed method uses a separation of time scales between the resolved and subscale variables to derive a reduced-order model with cubic closure terms for the truncated modes, generalizing the classic Stuart–Landau equation. The leading-order cubic terms are determined by averaging out fast variables through a perturbation series approximation of the action of a stochastic Koopman operator. We show analytically that this multiscale closure model can capture both the effects of mean-flow deformation and the energy cascade before demonstrating improved stability and accuracy in models of chaotic lid-driven cavity flow and vortex pairing in a mixing layer. This approach to closure modelling establishes a general theory for the origin and role of cubic nonlinearities in low-dimensional models of incompressible flows.
We generalise some known results for limit groups over free groups and residually free groups to limit groups over Droms RAAGs and residually Droms RAAGs, respectively. We show that limit groups over Droms RAAGs are free-by-(torsion-free nilpotent). We prove that if S is a full subdirect product of type $FP_s(\mathbb{Q})$ of limit groups over Droms RAAGs with trivial center, then the projection of S to the direct product of any s of the limit groups over Droms RAAGs has finite index. Moreover, we compute the growth of homology groups and the volume gradients for limit groups over Droms RAAGs in any dimension and for finitely presented residually Droms RAAGs of type $FP_m$ in dimensions up to m. In particular, this gives the values of the analytic $L^2$-Betti numbers of these groups in the respective dimensions.