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Who gets to have a voice, and what does it mean? Questions of vocal ontology and ethics are perennial, but in a world where the ability to sample the voices of others or to synthesize new ones in pursuit of both creative and commercial endeavours is available more widely than ever before, the relationship of the voice to the individual body, agency, and rights is invested with a new urgency. Through a discussion ranging from The Little Mermaid to Kanye West, Cathy Berberian to Holly Herndon, this short provocation considers the manifold ways in which we find, have, and borrow voices.
Here, we show that the thrust force of oscillating airfoils calculated within the linearised potential flow approach by means of the vortex impulse theory coincides with the one resulting from the integration of the unsteady pressure distribution around the solid obtained by Garrick (1936) when the vertical component of the wake velocity is calculated self-consistently and the analysis retains the contribution of the flux of horizontal momentum induced by the starting vortex. The limitations of the self-consistent linearised potential flow approach for predicting the thrust force of airfoils oscillating periodically with small amplitudes but large values of the reduced frequency are also discussed, as well as the reasons behind the ability of other results in the literature to approximate measurements better than Garrick’s theory. In fact, for those cases in which the airfoil oscillates periodically, the flux of horizontal momentum induced by the starting vortex is negligible and the vortices in the wake are convected parallel to the free-stream velocity, we have deduced an equation for the mean thrust coefficient which differs from previously published results and is in agreement with experimental and numerical results. In addition, for those cases in which the airfoil is suddenly set into motion, we have also deduced an equation that retains the effect of the starting vortex and correctly quantifies the transient thrust force.
La communication constitue un élément déterminant dans la participation sociale des personnes aînées. Or, les interactions entre ces dernières et le personnel d’institutions publiques, dont les bibliothèques, demeurent peu étudiées. Cette étude visait donc à identifier les composantes déterminantes de l’interaction entre les personnes aînées et le personnel de la bibliothèque. Des entrevues individuelles et de groupes ont été menées auprès de 10 personnes employées et de 19 personnes aînées avec et sans troubles cognitifs ou de communication, puis analysées qualitativement. Un modèle théorique représentant comment l’interaction en bibliothèque est influencée par des facteurs relatifs à la personne aînée (ex.: besoin d’interaction), la personne employée (ex.: stratégies de communication), l’environnement (ex.: achalandage) et la modalité (ex.: téléphone) a été développé. L’identification de ces facteurs pourra soutenir les bibliothèques dans l’adaptation de leurs modes de fonctionnement pour promouvoir la pleine participation sociale des personnes aînées.
We show that passively mode-locked lasers, subject to feedback from a single external cavity can exhibit large timing fluctuations on short time scales, despite having a relatively small long-term timing jitter. This means that the commonly used von Linde and Kéfélian techniques of experimentally estimating the timing jitter can lead to large errors in the estimation of the arrival time of pulses. We also show that adding a second feedback cavity of the appropriate length can significantly suppress noise-induced modulations that are present in the single feedback system. This reduces the short time-scale fluctuations of the interspike interval time and, at the same time, improves the variance of the fluctuation of the pulse arrival times on long time scales.
Let p be an odd prime, and suppose that $E_1$ and $E_2$ are two elliptic curves which are congruent modulo p. Fix an Artin representation $\tau\,{:}\,G_{F}\rightarrow \mathrm{GL}_2(\mathbb{C})$ over a totally real field F, induced from a Hecke character over a CM-extension $K/F$. Assuming $E_1$ and $E_2$ are ordinary at p, we compute the variation in the $\mu$- and $\lambda$-invariants for the $\tau$-part of the Iwasawa Main Conjecture, as one switches from $E_1$ to $E_2$. Provided an Euler system exists, it will follow directly that IMC$(E_1,\tau)$ is true if and only if IMC$(E_2,\tau)$ is true.
In this paper, the notion of structural completeness is explored in the context of a generalized class of superintuitionistic logics that also involve systems that are not closed under uniform substitution. We just require that each logic must be closed under $D$-substitutions assigning to atomic formulas only $\vee$-free formulas. For these systems, we introduce four different notions of structural completeness and study how they are related. We focus on superintuitionistic inquisitive logics that validate a schema called Split and have the disjunction property. In these logics, disjunction can be interpreted in the sense of inquisitive semantics as a question-forming operator. It is shown that a logic is structurally complete with respect to $D$-substitutions if and only if it validates Split. Various consequences of this result are explored. For example, it is shown that every superintuitionistic inquisitive logic can be characterized by a Kripke model built from $D$-substitutions. We also formulate an algebraic counterpart of this result that says that the Lindenbaum–Tarski algebra ${\mathscr{H}}$ of any inquisitive logic can be embedded into the Heyting algebra formed from left ideals of endomorphisms on ${\mathscr{H}}$. Additionally, we resolve a conjecture concerning superintuitionistic inquisitive logics due to Miglioli et al. and show that a false conjecture about superintuitionistic logics due to Minari and Wroński becomes true in the broader space of regular generalized superintuitionistic logics.
Differences in labour market institutions and regulations between countries of the monetary union can cause divergent responses even to a common shock. We augment a multi-country model of the euro area with search and matching framework that differs across Ricardian and hand-to-mouth households. In this setting, we investigate the implications of cross-country heterogeneity in labour market institutions for the conduct of monetary policy in a monetary union. We compute responses to demand and supply shocks under the Taylor rule, asymmetric unemployment targeting, and average inflation targeting. For each rule we distinguish between cases with lower or higher weight on the unemployment gap. Across all rules, responding to unemployment leads to lower losses of employment. Responding to unemployment reduces cross-country differences within the monetary union and consumption inequality between rich and poor households within each country.
Neoliberalism can be defined as the drive to shield capitalism from the scrutiny and accountability of democratic processes. This definition is particularly relevant to the creation of the euro, as it reflects some imbalances of the 1992 Maastricht Treaty creating the European Union (EU). The monetary union was designed to function with full independence, largely beyond the reach of democratic deliberations. This article investigates whether this outcome was intentional. It argues that the asymmetric structure of the Economic and Monetary Union (EMU) was purposefully crafted, as the European policymakers involved in the negotiations were acutely aware of the imperfections of the system being developed. However, these shortcomings were not specifically aligned with a particular neoliberal ideology. Instead, this article shows they resulted from a broader set of concerns, primarily driven by a reluctance to centralise decision-making power at the EU level due to fears of losing aspects of national sovereignty. Understanding the unintentional nature of this outcome is crucial, as confusing what is accidental with what is deliberate can lead to misunderstandings about the motivations behind EMU and misconceive the paths for its reform.
Using firms’ online job postings, we identify economically related peer firms in the labor market. Firms’ labor peers are vastly different from their industry peers, where the overlap is about 20%. Returns of labor-linked firms strongly comove, suggesting common responses to labor market shocks on average. However, industry shocks can affect firms outside the industry through the labor network, leading to substitution effects between labor peers. Last, we show that investors do not promptly incorporate news about labor-linked firms, leading to predictable subsequent returns. A long-short strategy exploiting this delay generates an average annualized excess return of 9%.
The function of aortic heart valves is to prevent regurgitant flow from the aorta into the left ventricle. A higher regurgitant flow is observed in bileaflet mechanical heart valves (BMHVs) compared with bioprosthetic heart valves (BHVs) because of their delayed closure. Here, we investigate this behaviour through fluid–structure interaction simulations of a BMHV compared with a trileaflet mechanical heart valve (TMHV) and a BHV under similar conditions. We find that the TMHV and BHV begin to close during the systolic deceleration, whereas BMHV only begins to close when the flow reverses. We found this to be related to hemodynamics as the TMHV and BHV, when fully opened, generate a central jet-dominant flow, whereas the BMHV generates triple jets with lateral jets being wider than its central jet. The flow deceleration of the central jet during late systole is higher than that of the sinuses, which results in a lower pressure in the central region than the sinuses to drive the leaflets of the TMHV and BHV towards the centre for closure. Conversely, the pressure on the sinus- and central flow-sides of the BMHV leaflets is nearly the same until the end of systole. We, contrary to what classically believed, did not find any evidence of sinus vortices generating high pressure or viscous stresses to initiate valve closure. Overall, the results suggest that the generation of a strong central jet and the direction of the leaflets’ closure towards the centre are the design principles to ensure an early valve closure and minimise regurgitation.
A real number is simply normal to base b if its base-b expansion has each digit appearing with average frequency tending to $1/b$. In this article, we discover a relation between the frequency at which the digit $1$ appears in the binary expansion of $2^{p/q}$ and a mean value of the Riemann zeta function on vertical arithmetic progressions. In particular, we show that
We present the measurements of the decay of stationary turbulence at Reynolds numbers based on the Taylor microscale $Re_{\lambda }=493, 599, 689$ produced in a large-scale von Kármán flow using stereoscopic particle image velocimetry. First, steady-state conditions were established, after which the impellers were simultaneously and abruptly stopped, and the turbulent decay was measured over 10–20 impeller rotation periods. A total of 258 decay experiments were performed. The temporal evolution of the ensemble-averaged turbulent kinetic energy (TKE) showed excellent agreement over all $Re_{\lambda }$ and exhibited two distinct phases: a short, initial transition phase where the TKE remained almost constant due to the inertia of the flow and lasted approximately $0.4$ impeller rotations, followed by a classical power-law decay. To extract the decay exponent $n$, a curve-fitting function based on a one-dimensional energy spectrum was used, and successfully captured the entire measured decay process. A value $n=1.62$ was obtained based on ensemble-averaged TKE. However, different decay exponents were found for individual velocity components: $n=1.38$ for the axial component consistent with various reports in the literature and Loitsiansky’s prediction ($n=1.43$), and $n=1.99$ for the radial and circumferential components indicating saturation/confinement effects. Similarly, the longitudinal integral length scale in the axial direction grew as $L\propto t^{2/7}$, whereas it remained nearly constant in the radial direction. Finally, the evolution of the ensemble-averaged velocity gradients showed that after the impellers were stopped, the mean flow pattern persisted for a short time before undergoing a large-scale reversal before the onset of the turbulent decay.
This paper presents a low-profile miniaturized dual-band antenna utilizing the quarter-mode substrate integrated waveguide (QMSIW) structure. The two modes of TE110 and TE220 of a single QMSIW structure are employed, enabling a dual-band operation. The frequency ratio between the two bands can be tuned by loading a capacitive structure, which is comprised of a capacitive-loaded patch and a short circuit post, inside the QMSIW structure. By introducing parasitic QMSIW structures through magnetic coupling, a dual-band antenna with enhanced bandwidths is achieved. The antenna has dimensions of smaller than 400 mm2 (0.048λL2) with a uniform height of 1.4 mm (0.016λL). Measurement results indicate that the −6 dB impedance bandwidths of the antennas can cover the 5G N78 (3.3–3.6 GHz) and N79 (4.8–5 GHz) bands, and the average efficiencies is better than −2.5 dB. To the authors’ knowledge, the proposed designs offer dual-wideband operation while having the smallest planar dimension compared to the previously reported antennas. Furthermore, an extended electric coupling dual-band antenna configuration is also described and measured, which achieves similar bandwidth extension as the proposed antenna.
The transport of a passive scalar at unity Schmidt number in a turbulent flow over a random sphere pack is investigated by direct numerical simulation. A bed-normal scalar flux is introduced by prescribed scalar concentration values at the bottom and top domain boundaries, whereas sphere surfaces are impermeable to scalar fluxes. We analyse eight different cases characterised by friction Reynolds numbers $Re_\tau \in [150, 500]$ and permeability Reynolds numbers $Re_K \in [0.4, 2.8]$ at flow depth-to-sphere diameter ratios of $h/D \in \{ 3, 5, 10 \}$. The dimensionless roughness heights lie within $k_s^+ \in [20,200]$. The free-flow region is dominated by turbulent scalar transport and the effective diffusivity scales with flow depth and friction velocity. Near the interface, dispersive scalar transport and molecular diffusion gain importance, while the normalised near-interface effective diffusivity is approximately proportional to $Re_K^2$. Even without a macroscopic bed topography, local hotspots of dispersive scalar transport are observed (‘chimneys’), which are linked to strong spatial variations in the time-averaged scalar concentration field. The form-induced production of temporal scalar fluctuations, however, goes along with a homogenisation of those spatial variations of the scalar concentration field due to turbulent fluid motion. Accordingly, form-induced production determines the interaction of turbulent and dispersive scalar transport at the interface. With increasing $Re_K$, momentum from the free-flow region entrains deeper into the sediment bed, such that the form-induced production intensifies and peaks at lower positions. As a result, the transition from dispersive to turbulent scalar transport is observed deeper inside the sphere pack.