Low-frequency phenomena in an incompressible pressure-induced laminar separation bubble (LSB) on a flat plate is investigated using direct numerical simulation. The LSB configuration of Spalart and Strelets (J. Fluid Mech., vol. 403, 2000, pp. 329–349) is used. Wall pressure spectra indicate low-frequency-flapping $(St \sim 0.08)$ and high-frequency-shedding $(St \sim 1.52)$ regimes. Conditional velocity averages based on the fraction of reversed flow reveal the low frequency as an expansion/contraction of the LSB. While the high frequency only exhibits exponential growth within the LSB up to breakdown of the spanwise rollers, the low frequency and velocity fluctuations exhibit exponential growth upstream of separation. Instantaneous flow fields reveal large streamwise streaky structures forming within the LSB and extending past reattachment, much like high and low speed streaks in turbulent boundary layers. A predominance of sweep-like events ($Q4$) is observed during contraction and of ejection-like events ($Q2$) during expansion. These motions appear as dominant low-frequency modes in three-dimensional proper orthogonal and dynamic mode decompositions, exhibiting spatial amplification from separation to reattachment. The advection of a group of spanwise alternating streaky structures past the LSB results in an overall contraction after which the bubble expands to its ‘unforced’ state in the absence of the streaks. The low frequency then corresponds to the time it takes for streaks to form, amplify and advect past the LSB from separation to reattachment. This behaviour is linked to the mean flow deformation reported by Marxen and Rist (J. Fluid Mech., vol. 660, 2010, pp. 37–54), where the presence of streaks results in reduced mean bubble size. The formation of these streaky structures, in the absence of free stream turbulence, may be attributed to an absolute instability of the LSB due to the development of a secondary bubble within the primary.

This Article brings new perspectives on the well-known Viking and Laval cases, decided by the Court of Justice of the European Union (CJEU) in December 2007, by studying the processes and modalities of the construction of this case law as a major defeat for social Europe. It demonstrates that the political and legal implications of these two rulings were socially constructed by a variety of European actors (especially trade unionists and academics specialising in labour law) rather than legally inscribed in the rulings. In doing so, the author defends a constructivist approach in the analysis of European case law, both contextual and processual. The Article is divided into two parts. The first retraces the pre-ruling construction of the Viking and Laval cases, and shows that trade union and academic actors as well as parliamentarians worked to construct the judgements on these cases as decisive landmarks for social Europe. The second part considers the process of interpretation of the rulings after they were delivered by the CJEU. It evidences the central role played by trade union and academic actors in promoting a critical reading of the rulings, arguing that the Court subordinated social rights to economic liberties. The Article concludes by showing that this interpretation has tended to become subject to consensus, to the extent that it is now European common sense.

Measurements of wall-pressure and velocity fluctuations are performed in a family of three incompressible, pressure-induced, turbulent separation bubbles (TSBs) of varying sizes, with an emphasis on the energetic low and medium frequencies. In all three cases the streamwise distribution of wall-pressure fluctuations shows a bi-modal character, with a first local maximum close to the position of maximum adverse pressure gradient and a second local maximum at the very end of the region of intermittent back flow. The first maximum is shown to be caused by the superposition of two separate phenomena occurring at approximately the same streamwise position: first, the pressure signature of a low-frequency contraction and expansion (breathing) of the TSBs, whose amplitude is shown to increase with the size of the separation bubble, and second, the effect of the adverse pressure gradient on the turbulent structures responsible for the pressure fluctuations in the attached boundary layer. The second maximum of the wall-pressure fluctuation coefficient also increases with the size of the TSB and is associated with the convection of large structures within the shear layer. Possible scaling laws are examined to show that both the local maximum Reynolds shear stress ${-\rho \overline {u'v'}_{max}}$ and the local maximum wall-normal stress ${\rho \overline {v'v'}_{max}}$ are adequate to scale the pressure fluctuations along the TSBs, with a better match when low frequencies are removed. Furthermore, a comparison with existing data from the literature illustrates the effects of Reynolds number and TSB size on the wall-pressure and velocity fluctuations. Finally, measurements in the spanwise direction demonstrate that, although corner effects strongly distort the average flow, the scaling of wall-pressure fluctuations with the turbulent stresses remains relatively unaffected. The present results provide new insights into the unsteady character of pressure-induced turbulent separation bubbles and their associated wall-pressure fluctuations.

Over the past decade, a growing interest has developed on the archaeology, palaeontology, and palaeoenvironments of the Arabian Peninsula. It is now clear that hominins repeatedly dispersed into Arabia, notably during pluvial interglacial periods when much of the peninsula was characterised by a semiarid grassland environment. During the intervening glacial phases, however, grasslands were replaced with arid and hyperarid deserts. These millennial-scale climatic fluctuations have subjected bones and fossils to a dramatic suite of environmental conditions, affecting their fossilisation and preservation. Yet, as relatively few palaeontological assemblages have been reported from the Pleistocene of Arabia, our understanding of the preservational pathways that skeletal elements can take in these types of environments is lacking. Here, we report the first widespread taxonomic and taphonomic assessment of Arabian fossil deposits. Novel fossil fauna are described and overall the fauna are consistent with a well-watered semiarid grassland environment. Likewise, the taphonomic results suggest that bones were deposited under more humid conditions than present in the region today. However, fossils often exhibit significant attrition, obscuring and fragmenting most finds. These are likely tied to wind abrasion, insolation, and salt weathering following fossilisation and exhumation, processes particularly prevalent in desert environments.

The origins of agriculture in South-west Asia is a topic of continued archaeological debate. Of particular interest is how agricultural populations and practices spread inter-regionally. Was the Arabian Neolithic, for example, spread through the movement of pastoral groups, or did ideas perhaps develop independently? Here, the authors report on recent excavations at Alshabah, one of the first Neolithic sites discovered in Northern Arabia. The site’s material culture, environmental context and chronology provide evidence suggesting that well-adapted, seasonally mobile, pastoralist groups played a key role in the Neolithisation of the Arabian Peninsula.

Fish-hooks discovered among grave goods associated with an adult female burial at the Tron Bon Lei rockshelter on the island of Alor in Indonesia are the first of their kind from a Pleistocene mortuary context in Southeast Asia. Many of the hooks are of a circular rotating design. Parallels found in various other prehistoric contexts around the globe indicate widespread cultural convergence. The association of the fish-hooks with a human burial, combined with the lack of alternative protein sources on the island, suggest that fishing was an important part of the cosmology of this community. The Tron Bon Lei burial represents the earliest-known example of a culture for whom fishing was clearly an important activity among both the living and the dead.

Extinctions have altered island ecosystems throughout the late Quaternary. Here, we review the main historic drivers of extinctions on islands, patterns in extinction chronologies between islands, and the potential for restoring ecosystems through reintroducing extirpated species. While some extinctions have been caused by climatic and environmental change, most have been caused by anthropogenic impacts. We propose a general model to describe patterns in these anthropogenic island extinctions. Hunting, habitat loss and the introduction of invasive predators accompanied prehistoric settlement and caused declines of endemic island species. Later settlement by European colonists brought further land development, a different suite of predators and new drivers, leading to more extinctions. Extinctions alter ecological networks, causing ripple effects for islands through the loss of ecosystem processes, functions and interactions between species. Reintroduction of extirpated species can help restore ecosystem function and processes, and can be guided by palaeoecology. However, reintroduction projects must also consider the cultural, social and economic needs of humans now inhabiting the islands and ensure resilience against future environmental and climate change.

Mammalian carnivores are rarely incorporated in paleoenvironmental reconstructions, largely because of their rarity within the fossil record. However, multivariate statistical modeling can be successfully used to quantify specific anatomical features as environmental predictors. Here we explore morphological variability of the humerus in a closely related group of predators (Felidae) to investigate the relationship between morphometric descriptors and habitat categories. We analyze linear measurements of the humerus in three different morphometric combinations (log-transformed, size-free, and ratio), and explore four distinct ways of categorizing habitat adaptations. Open, Mixed, and Closed categories are defined according to criteria based on traditional descriptions of species, distributions, and biome occupancy. Extensive exploratory work is presented using linear discriminant analyses and several fossils are included to provide paleoecological reconstructions.

We found no significant differences in the predictive power of distinct morphometric descriptors or habitat criteria, although sample splitting into small and large cat guilds greatly improves the stability of the models. Significant insights emerge for three long-canine cats: Smilodon populator, Paramachairodus orientalis, and Dinofelis sp. from Olduvai Gorge (East Africa). S. populator and P. orientalis are both predicted to have been closed-habitat adapted taxa. The false “sabertooth” Dinofelis sp. from Olduvai Gorge is predicted to be adapted to mixed habitat. The application of felid humerus ecomorphology to the carnivoran record of Olduvai Gorge shows that the older stratigraphic levels (Bed I, 1.99–1.79 Ma) included a broader range of environments than Beds II or V, where there is an abundance of cats adapted to open environments.