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In this paper, we study wave scattering and radiation by a surface-piercing vertical truncated metamaterial cylinder composed of a closely spaced array of thin vertical barriers, between which fluid can flow. A theoretical model is developed under full depth-dependent linearised water wave theory, where an effective medium equation and effective boundary conditions are employed, respectively, to describe the fluid motion inside the cylinder and match the flow between the fluid regions in and outside the metamaterial cylinder. A damping mechanism is introduced at the surface of the fluid occupied by the metamaterial cylinder to consider the wave power dissipation in narrow gaps between the thin vertical plates. The wave excitation forces acting on the cylinder and the hydrodynamic coefficients can be calculated straightforwardly in terms of the velocity potential inside the cylinder. An alternative way is by using the velocity potential outside the cylinder, the expression of which has the reduction of the integral and an infinite accumulation that are included in the straightforward expression. The results highlight the patterns of the radiated waves induced by the oscillation of the cylinder and the characteristics of the hydrodynamic coefficients. The metamaterial cylinder when fixed in place and with a damping mechanism included is found to capture more wave power than that of a traditional axisymmetric heaving wave energy converter over a wide range of wave frequencies.
We study numerically the microjetting mode obtained when a fluid is injected through a tube submerged in a uniaxial extensional flow. The steady solution to the full nonlinear Navier–Stokes equations is calculated. We obtain the linear global modes determining the linear stability of the steady solution. For sufficiently large outer viscosity, the flow remains stable for infinitely small values of the injected flow rate. This implies that jets with vanishing diameters can be produced regardless of the jet viscosity and outer flow strength. For a sufficiently small inner-to-outer viscosity ratio, the microjetting instability is associated only with the flow near the entrance of the jet. The tapering meniscus stretches and adopts a slender quasiconical shape. Consequently, the cone tip is exposed to an intense outer flow, which stabilizes the flow in the cone–jet transition region. This work presents the first evidence that fluid jets with arbitrarily small diameters can be stably produced via tip streaming. The results are related to those of a droplet in a uniaxial extensional flow with its equator pinned to an infinitely thin ring. The pinning of the equator drastically affects the droplet stability and breakup.
The relationship between alcohol consumption and cognition is still controversial. This is a cross-sectional population-based study conducted in Caeté (MG), Brazil, where 602 individuals aged 75+ years, 63.6% female, and with a mean education of 2.68 years, were submitted to thorough clinical assessments and categorized according to the number of alcoholic beverages consumed weekly. The prevalence rates of previous and current alcohol consumption were 34.6% and 12.3%, respectively. No association emerged between cognitive diagnoses and current/previous alcohol consumption categories. Considering current alcohol intake as a dichotomous variable, the absence of alcohol consumption was associated with dementia (OR = 2.34; 95%CI: 1.39–3.90) and worse functionality (p = 0.001). Previous consumption of cachaça (sugar cane liquor) increased the risk of dementia by 2.52 (95%CI: 1.25–5.04). The association between the consumption of cachaça and dementia diagnosis has not been described before.
During the sixteenth century, the medieval Palace of Westminster went from being the most-used royal palace, where the king lived and worked alongside his administration, to becoming solely the home of the law-courts, Parliament, and the offices of state. At the same time, the numbers of individuals who came to the palace seeking governance or to take part in the business of the law-courts increased over the course of the century. While Westminster had earlier been a public venue for governance and royal display, the increasing absence of the English monarch from the palace created alternative uses. Political culture came to focus on Westminster as entirely separate from the court. This article explores how these changing uses created new forms of political and administrative culture. It examines how the administrative offices, particularly the Exchequer, were remade to accommodate changing financial demands and the increasing contact between individuals and the Crown. It argues that the repurposing of the Palace of Westminster created a distinctly different set of relationships between the Crown and the public. This gave the institutions that called the palace home the space to develop as bodies that drew their legitimacy from their representation of the community of the realm as a whole.
Monitoring venous saturation allows identification of inadequate systemic oxygen delivery. The aim was to develop a model using non-invasive haemodynamic variables to estimate the inferior caval vein saturation and to determine its prognostic utility.
Methods:
This is a single-centre, retrospective study. A Bayesian Pearson’s correlation was conducted to model the inferior caval vein saturation. Next, a Bayesian linear regression was conducted for data from all the patients and from only those with parallel circulation. Venous saturation estimations were developed. The correlation of these estimates to the actual inferior caval vein saturation was assessed. The resulting models were then applied to two validation cohorts: biventricular circulation (arterial switch operation) and parallel circulation (Norwood operation).
Results:
One hundred and thirteen datasets were collected across 15 patients. Of which, 65% had parallel circulation. In all patients, the measured and estimated inferior caval vein saturations had a moderate and significant correlation with a coefficient of 0.64. In patients with parallel circulation, the measured and estimated inferior caval vein saturation had a moderate and significant correlation with a coefficient of 0.61. In the biventricular circulation cohort, the estimated inferior caval vein saturation had an area under the curve of 0.71 with an optimal cut-off of 49. In the parallel circulation cohort, the estimated interior caval vein saturation had an area under the curve of 0.83 with an optimal cut-off of 24%.
Conclusion:
The inferior caval vein saturation can be estimated utilising non-invasive haemodynamic data. This estimate has correlation with measured inferior caval vein saturations and offers prognostic utility.
We introduce a natural two-cardinal version of Bagaria’s sequence of derived topologies on ordinals. We prove that for our sequence of two-cardinal derived topologies, limit points of sets can be characterized in terms of a new iterated form of pairwise simultaneous reflection of certain kinds of stationary sets, the first few instances of which are often equivalent to notions related to strong stationarity, which has been studied previously in the context of strongly normal ideals. The non-discreteness of these two-cardinal derived topologies can be obtained from certain two-cardinal indescribability hypotheses, which follow from local instances of supercompactness. Additionally, we answer several questions posed by the first author, Holy and White on the relationship between Ramseyness and indescribability in both the cardinal context and in the two-cardinal context.
Drawing upon iconological theory, this article argues that mirrors and blood were regarded as a conceptually linked pair within the imperial ideology of Teotihuacan, Mexico from the second century onward. The relationship between blood and mirrors is shown to have codified with the construction of the Pyramid of the Feathered Serpent, Teotihuacan's third largest edifice. This monument's facade was adorned with hundreds of monumental sculptures of oracular mirrors, some number of which incorporated actual mirrors formed of obsidian. I demonstrate that the Teotihuacan mirror sign took obsidian, a form of black volcanic glass that was intensively worked in the city, as a key referent. This monument was also the site of a historically large human sacrifice of more than 200 individuals, an event argued here to have involved bloodletting with obsidian knives and blades. I note that Teotihuacan interest in the mirror icon increased in concert with the city's residents’ application of the reflective material of obsidian to warring and other blood-spilling behaviors. The mirror icon evoked both obsidian as a radiant material, as well as obsidian's potential for application to forceful martial actions. The article concludes that this icon in part signified imperial force, which was made real through the weaponization of the smoking glass.
Let $S=K[x_1,\ldots ,x_n]$ be the polynomial ring over a field K, and let A be a finitely generated standard graded S-algebra. We show that if the defining ideal of A has a quadratic initial ideal, then all the graded components of A are componentwise linear. Applying this result to the Rees ring $\mathcal {R}(I)$ of a graded ideal I gives a criterion on I to have componentwise linear powers. Moreover, for any given graph G, a construction on G is presented which produces graphs whose cover ideals $I_G$ have componentwise linear powers. This, in particular, implies that for any Cohen–Macaulay Cameron–Walker graph G all powers of $I_G$ have linear resolutions. Moreover, forming a cone on special graphs like unmixed chordal graphs, path graphs, and Cohen–Macaulay bipartite graphs produces cover ideals with componentwise linear powers.