We study the coupled settling, deformation and mixing dynamics of a dense blob of fluid falling in an axially (vertically) linearly stratified Taylor–Couette cell (operated in a laminar stable regime). This configuration allows the independent analysis of stretching dynamics, driven by radial (horizontal) velocity variations, and settling dynamics, driven by buoyancy forces associated with vertical density variations. As the blob settles, it is stretched in the horizontal plane and forms an elongated lamella. Through the competing effects of transverse compression of the lamella due to this shear-induced stretching and broadening due to diffusion, the lamella irreversibly mixes with ambient fluid, thus progressively adjusting its own density towards that of the ambient fluid. Eventually, the lamella settling stops at a final equilibrium position that depends on the ambient vertical density gradient and the rate at which it has been deformed by the horizontal shear. We show how this final position is determined by stretching-enhanced diffusion, i.e. mixing. We demonstrate that a theoretical mixing model compares favourably with experiments with various Froude numbers (quantifying the relative strength of the horizontal shear and the vertical stratification) and construct a new criterion for the energetic ‘efficiency’ of this mixing process that explicitly captures its inherently diffusive character.

The flow inside a rotating annulus tilted with respect to gravity is characterized experimentally and theoretically. As in the case of a tilted rotating cylinder the flow is forced by the free surface, maintained flat by gravity. It leads to resonances of global inertial modes (Kelvin modes) when the height of fluid is a multiple of half the wavelength of the mode. The divergence of the mode is saturated by viscous effects at the resonance. The maximum amplitude scales as the Ekman number to the power $-1/2$ when surface Ekman pumping is dominant, and to the power $-1$ when volumic damping is dominant. An analytical prediction is given with no fitting parameter, in excellent agreement with experimental results. At lower Ekman numbers, the flow destabilizes with respect to a triadic resonance instability, as already observed by Xu & Harlander (Phys. Rev. Fluids, 2020). We provide here a linear stability analysis leading to the viscous threshold of the instability for small tilt angles. For large tilt angles, a centrifugal instability is observed due to the acceleration of the flow by the inner cylinder. Finally, the features of the turbulent flow and its mixing efficiency are characterized experimentally. We underline the potential interest of this configuration for bioreactors.

The transport induced by ocean mesoscale eddies remains unresolved in most state-of-the-art climate models and needs to be parametrized instead. The natural scale separation between the forcing and the emergent turbulent flow calls for a diffusive parametrization, where the eddy-induced fluxes are related to the large-scale gradients by a diffusion tensor. The standard parametrization scheme in climate modelling consists in adopting the Gent–McWilliams/Redi (GM/R) form for the diffusion tensor, initially put forward based on physical intuition and educated guesses before being put on firm analytical footing using a thickness-weighted average (TWA). In the present contribution, we provide a direct derivation of this diffusion tensor from the quasi-geostrophic (QG) dynamics of a horizontally homogeneous three-dimensional patch of ocean hosting a large-scale vertically sheared zonal flow on the $\beta$ plane. The derivation hinges on the identification of a useful cross-invariant defined as the product of the buoyancy and QG potential vorticity fluctuations. While less general than the TWA approach, the present QG framework leads to rigorous constraints on the diffusion tensor. First, there is no diapycnal diffusivity arising in the QG GM/R tensor for low viscosity and small-scale diffusivities. The diffusion tensor then involves only two vertically dependent coefficients, namely the GM transport coefficient $K_{GM}(z)$ and the Redi diffusivity $K_R(z)$. Second, as identified already by previous authors, the vertical structures of the two coefficients are related by the so-called Taylor–Bretherton relation. Finally, while the two coefficients differ generically in the interior of the water column, we show that they are equal to one another near the surface and near the bottom of the domain for low-enough dissipative coefficients. We illustrate these findings by simulating numerically the QG dynamics of a horizontally homogeneous patch of ocean hosting a vertically sheared zonal current resembling the Antarctic Circumpolar Current.

This article investigates the development of wh-in-situ questions in French by examining a three-year kindergarten dataset of spontaneous productions with 16 children between 2;5 and 5;11. The distribution of the wh-phrases is statistically examined in relation to age, verb form (Fixed be form c’est ‘it is’ vs. Free be forms vs. Free lexical verbs), and grammatical category of the wh-word (Pronoun vs. Adverb). Results show that wh-in-situ remains prevalent throughout the period despite a steady increase in wh-ex-situ. Verb form (Fixed vs. All free forms) is a discriminating variable for the wh-position in all three years, and it interacts with the category of the wh-word. The Fixed be form c’est favours in-situ wh-pronouns (c’est qui Taz ?), whereas the Free forms favour wh-ex-situ questions, and massively co-occur with wh-adverbs (combien ça coûte ?). The emergence of the ex-situ qu’est-ce que ‘what is it that’, as opposed to the in-situ quoi ‘what’, is identified as a factor accounting for the gradual increase in wh-ex-situ. Finally, most outliers (wh-in-situ with Free forms) are shown to belong to the same paradigm as c’est in-situ questions: non-presuppositional questions, which are visible from the frequent use of là ‘there’, like c’est, a deictic item.

The present paper investigates theoretically and experimentally the boundary layer generated by a stably stratified fluid flowing horizontally along a surface tilted in the transverse direction and deformed by sinusoidal undulations with crests perpendicular to the flow direction. In the absence of undulations, a weak transverse velocity proportional to the normal velocity is created such that the flow remains purely horizontal. In the presence of undulations of amplitude $h$, a stronger transverse flow is generated that exhibits a singular behaviour at the critical altitude where the frequency of the perturbation matches the buoyancy frequency of the fluid. This baroclinic critical layer was previously analysed by Passaggia et al. (J. Fluid Mech., vol. 751, 2014, pp. 663–684) for a boundary layer flow with a small sliding velocity on the surface. Here, the no-slip boundary condition of the experimental flow is applied. For this purpose, we solve the viscous sub-layer to obtain a complete theoretical model for the solution in the critical layer without any adjusting parameter. The theoretical predictions for the transverse velocity are compared with experimental measurements, and a good quantitative agreement is demonstrated. Compared with the sliding case, the no-slip boundary condition on the surface reduces the amplitude of the critical layer solution by a factor $Re^{-1/3}$, where the Reynolds number Re is defined using the velocity at infinity and the thickness of the boundary layer. As a consequence, the transverse velocity has a maximum in the critical layer of order $h$, but it still induces a shear rate of order $h\,Re^{1/3}$.

The concept of quality of life in animals is closely associated with the concepts of animal sentience and animal welfare. It reflects a positive approach that inquires what animals like or prefer doing. The assessment of farm animal welfare requires a good understanding of the animals' affective experience, including their emotions. However, affective experience in animals is difficult to measure because of the absence of verbal communication. Recent studies in the field of cognitive psychology have shown that affective experience can be investigated without using verbal communication by examination of the interactions between emotions and cognition. On the one hand, appraisal theories provide a conceptual framework which suggests that emotions in humans are triggered by a cognitive process whereby the situation is evaluated on a limited number of elementary criteria such as familiarity and predictability. We have applied these appraisal theories to develop an experimental approach for studying the elementary criteria used by farm animals to evaluate their environment and the combinations of those criteria that trigger emotions. On the other hand, an increasing body of research, first in humans and then in other animals, suggests that emotions also influence cognitive processes by modifying attention, memory and judgement in a short- or long-term manner. Cognitive processes could therefore be manipulated and measured to provide new insights into how not only emotions but also more persistent affective states can be assessed in animals. Further work based on these cognitive approaches will offer new paradigms for improving our understanding of animal welfare, thus contributing to ‘a life of high quality’ in animals.

An online training package providing a concise synthesis of the scientific data underpinning EU legislation on enrichment and tail-docking of pigs was produced in seven languages, with the aim of improving consistency of professional judgements regarding legislation compliance on farms. In total, 158 participants who were official inspectors, certification scheme assessors and advisors from 16 EU countries completed an initial test and an online training package. Control group participants completed a second identical test before, and Training group participants after, viewing the training. In Section 1 of the test participants rated the importance of modifying environmental enrichment defined in nine scenarios from 1 (not important) to 10 (very important). Training significantly increased participants’ overall perception of the need for change. Participants then rated nine risk factors for tail-biting from 1 (no risk) to 10 (high risk). After training scores were better correlated with risk rankings already described by scientists. Scenarios relating to tail-docking and management were then described. Training significantly increased the proportion of respondents correctly identifying that a farm without tail lesions should stop tail-docking. Finally, participants rated the importance of modifying enrichment in three further scenarios. Training increased ratings in all three. The pattern of results indicated that participants’ roles influenced scores but overall the training improved: i) recognition of enrichments that, by virtue of their type or use by pigs, may be insufficient to achieve legislation compliance; ii) knowledge on risk factors for tail-biting; and iii) recognition of when routine tail-docking was occurring.

The aim of this study was to map farm animal welfare university education in an enlarged Europe with emphasis on identifying existing differences and gaps. Information on 210 courses dealing with farm animal welfare from 98 universities in 26 European countries were obtained. Statistical analysis was carried out on 155 of these courses within animal science or veterinary programmes, at Bachelor and Master level and with the countries grouped into five regions (North West Europe, Mediterranean, West Central Europe, East Central Europe and Balkans). There were significantly more hours of teaching in animal welfare in the North West region of Europe. This region also had more ‘interactive’ education methods, eg group discussion and farm visits, whereas West Central Europe had most ‘transmissive’ methods, eg lecturing. A course was more likely to be given in English in North West Europe (even when the UK and the Republic of Ireland were excluded from the analysis) and East Central Europe compared to West Central Europe and the Balkans. There appeared to be no regional differences in the content of the courses although the focus was significantly more ‘applied’, ie towards welfare assessment and legislation in the veterinary education and more ‘fundamental’, ie oriented towards ethology, physiology and ethics, in the animal science education. In summary, the main differences in farm animal welfare education across Europe seem to be in the reduced number of hours of education, less interactive teaching and fewer courses in English available to students outside the North West region.

The advection–diffusion of a small surface element of scalar in three dimensions (or of a small line element in two dimensions) is solved analytically thanks to the Ranz transform (Ranz, AIChE J., vol. 25, issue 1, 1979, pp. 41–47). As the quantum or elementary brick of any complex mixture, we call this element a diffuselet. Its evolution is computed numerically from the integration of the velocity gradient along the trajectory, as classically done for the Lyapunov exponents. The concentration profile across the diffuselet is obtained from the product of its initial orientation with a dimensionless tensor. Averaging over all initial orientations yields simple formulae for the mean scalar variance and the scalar probability distribution function (p.d.f.). This technique is then applied to two-dimensional and three-dimensional sine flows, in excellent agreement with direct numerical simulations. For these simple flows, the temporal integration is obtained analytically leading to simple integrals for the scalar variance and p.d.f. Statistics of stretching rates are calculated as well. The Lyapunov exponent is close to the value for short-time correlated flows (Kraichnan, J. Fluid Mech., vol. 64, issue 4, 1974, pp. 737–762) in the case of a small displacement during each step; it is close to the value for a simple shear in the case of a large displacement. The p.d.f. of stretching factors are log normal with a ratio between the mean and the variance equal to half the dimension of space for small displacements (in agreement with Kraichnan, J. Fluid Mech., vol. 64, issue 4, 1974, pp. 737–762), but increases strongly for large displacements.

Middle Eocene deep-sea sediment sequences cored at Ocean Drilling Program Site 1260 (Leg 207; equatorial Atlantic Ocean) yielded diverse and abundant radiolarian faunas that are conducive to biostratigraphic and palaeoceanographic research, as well as to the study of radiolarian diversity dynamics during this epoch of significant climate changes. However, many species present in these sediments still have not been formally described and are therefore neglected in most biodiversity surveys. In an effort to improve the taxonomic resolution of middle Eocene radiolarians, 15 new species of nassellarians are described and illustrated. The species are: Cymaetron? dilatatus n. sp., Eucyrtidium levisaltatrix n. sp. (Eucyrtidiidae), Siphocampe pollen n. sp., Spirocyrtis? renaudiei n. sp. (Artostrobiidae), Pterocyrtidium eep n. sp. (Rhopalosyringiidae), Petalospyris cometa n. sp., Petalospyris castanea n. sp. (Cephalospyrididae), Velicucullus armatus n. sp. (Theophormididae), Lychnocanium nimrodi n. sp. (Lithochytrididae), Aphetocyrtis zamenhofi n. sp., Aphetocyrtis? columboi n. sp., Aphetocyrtis? spheniscus n. sp. (Lophocyrtiidae), Albatrossidium regis n. sp., Albatrossidium annikasanfilippoae n. sp., and Phormocyrtis lazari n. sp. (Pterocorythidae). Stratigraphic range data are provided for each new species, as well as the orbitally tuned ages for their first and last occurrences. In addition to these new species, we also illustrate and document the stratigraphic distribution of four species described in early radiolarian studies and rarely reported since.

UUID: http://zoobank.org/b5993e6b-659b-4220-80c2-c6ddccc13793

Relative dispersion experiments are often analysed using theoretical predictions from two- and three-dimensional turbulence. These apply to infinite inertial ranges, assuming the same dispersive behaviour over all scales. With finite inertial ranges, the metrics are less conclusive. We examine this using pair separation probability density functions (PDFs), obtained by integrating a Fokker–Planck equation with different diffusivity profiles. We consider time-based metrics, such as the relative dispersion, and separation-based metrics, such as the finite scale Lyapunov exponent (FSLE). As the latter cannot be calculated from a PDF, we introduce a new measure, the cumulative inverse separation time (CIST), which can. This behaves like the FSLE, but advantageously has analytical solutions in the inertial ranges. This allows the establishment of consistency between the time- and space-based metrics, something which has been lacking previously. We focus on three dispersion regimes: non-local spreading (as in a two-dimensional enstrophy inertial range), Richardson dispersion (as in an energy inertial range) and diffusion (for uncorrelated pair motion). The time-based metrics are more successful with non-local dispersion, as the corresponding PDF applies from the initial time. Richardson dispersion is barely observed, because the self-similar PDF applies only asymptotically in time. In contrast, the separation-based CIST correctly captures the dependencies, even with a short (one decade) inertial range, and is superior to the traditional FSLE at large scales. Nevertheless, it is advantageous to use all measures together, to seek consistent indications of the dispersion.

A cylinder undergoes precession when it rotates around its axis and this axis itself rotates around another axis. In a precessing cylinder full of fluid, a steady and axisymmetric component of the azimuthal flow is generally present. This component is called a zonal flow. Although zonal flows have been often observed in experiments and numerical simulations, their origin has eluded theoretical approaches so far. Here, we develop an asymptotic analysis to calculate the zonal flow forced in a resonant precessing cylinder, that is when the harmonic response is dominated by a single Kelvin mode. We find that the zonal flow originates from three different sources: (1) the nonlinear interaction of the inviscid Kelvin mode with its viscous correction; (2) the steady and axisymmetric response to the nonlinear interaction of the Kelvin mode with itself; and (3) the nonlinear interactions in the end boundary layers. In a precessing cylinder, two additional sources arise due to the equatorial Coriolis force and the forced shear flow; however, they cancel exactly. The study thus generalises to any Kelvin mode, forced by precession or any other mechanism. The present theoretical predictions of the zonal flow are confirmed by comparison with numerical simulations and experimental results. We also show numerically that the zonal flow is always retrograde in a resonant precessing cylinder ($m=1$) or when it results from resonant Kelvin modes of azimuthal wavenumbers $m=2$, $3$ and, presumably, higher.

This study presents preliminary results of recent explorations at Iroungou (Gabon), a pre-colonial burial cave containing scattered skeletal remains of at least 28 men, women and children. The individuals, whose crania show cultural tooth ablation, were buried with abundant metallic objects, a combination with no known equivalent in West Central Africa.

In this article, the objective is to characterize the influence of a continuous stratification on wake-induced vibrations of a circular cylinder. Experimental results are obtained by towing a horizontal cylinder in a horizontal direction perpendicular to its axes, at a constant speed in a linearly stratified fluid made of salty water. The cylinder can move vertically since it is fixed to free-to-rotate arms. The diameter of the cylinder, the length of the arms and the translating speed are varied. Two flow-induced vibrations modes are observed. The first one is analogous to a vortex-induced vibration (VIV) mode: it is associated with a resonance between the vortex shedding frequency and its frequency is proportional to the natural frequency of the mechanical system, as can be predicted by the VIV theory generalized to low mass ratios. Large amplitude oscillations of the cylinder are found to occur in a large range of velocities also in agreement with the low-mass-ratio VIV theory. The second mode is interpreted as a galloping mode. It has a low frequency and a large amplitude, and occurs for low Froude numbers and long arms. It corresponds to the regimes when the buoyancy forces are larger than the inertial and vertical drag forces. By computing the forces on the cylinder, it is shown that stratification is the source of a destabilizing lift when the cylinder departs from its horizontal motion. Only a weak effect of the Reynolds number on the stability characteristics has been observed in the considered range ($500 < Re < 15\,000$).