An archaeological survey of Kitsissut, a remote island cluster in the High Arctic of Kalaallit Nunaat (Greenland), has revealed a human presence almost 4500 years ago, during the formation of a vital marine environment—Pikialasorsuaq polynya. Kitsissut is accessible only by a difficult open-water journey, and repeated occupation thus permits inferences on the sophistication of watercraft technology and navigational skill. Here, the authors argue that this demonstrable reach of Early Paleo-Inuit communities across marine and terrestrial ecosystems enhances our understanding of their lifeways and environmental legacy, raising critical new questions about Indigenous agency in shaping emerging Arctic ecosystems.

The linear stability of nanofluid boundary-layer flow over a flat plate is investigated using a two-phase formulation that incorporates the Brinkman (1952 J. Chem. Phys., vol. 20, pp. 571–581) model for viscosity along with Brownian motion (BM) and thermophoresis (TP), building upon the earlier work of Buongiorno (2006 J. Heat Transfer, vol. 128, pp. 240–250). Solutions to the steady boundary-layer equations reveal a thin nanoparticle concentration layer near the plate surface, with a characteristic thickness of $O({\textit{Re}}^{-1/2}{\textit{Sc}}^{-1/3})$, for a Reynolds number ${\textit{Re}}$ and Schmidt number ${\textit{Sc}}$. When BM and TP are neglected, the governing equations reduce to the standard Blasius formulation for a single-phase fluid, and the nanoparticle concentration layer disappears, resulting in a uniform concentration across the boundary layer. Neutral stability curves and critical conditions for the onset of the Tollmien–Schlichting (TS) wave are computed for a range of nanoparticle materials and volume concentrations. Results indicate that while the effects of BM and TP are negligible, the impact of nanoparticle density is significant. Denser nanoparticles, such as silver and copper, destabilise the TS wave, whereas lighter nanoparticles, like aluminium and silicon, establish a small stabilising effect. Additionally, the viscosity model plays a crucial role, with alternative formulations leading to different stability behaviour. Finally, a high Reynolds number asymptotic analysis is undertaken for the lower branch of the neutral stability curve.

We present a mathematical model for tsunami and induced magnetic anomalies originating from a time-dependent seabed deformation in an otherwise quiescent ocean over a conductive seafloor. The deformation is assumed to be a slender fault, whose lateral extension is much larger than the longitudinal scale. Using a perturbative method with multiple time scales and Green’s function approach, we examine the slow evolution of the wave field and induced magnetic anomaly over transoceanic distances from the fault. The model is validated against deep-ocean observations from the 2011 Tōhoku-oki tsunami. Our study reveals that lateral propagation in two horizontal dimensions decreases the period of both the surface wave and induced magnetic signal compared with one-horizontal-dimension scenarios. Over time, initially longitudinal wave propagation alters as wave fronts bend and stretch, affecting the magnetic signal accordingly. Interestingly, the magnetic anomaly gradually separates from the leading tsunami wave and travels ahead of the tsunami by a distance proportional to the fault’s longitudinal scale. We show that increased lateral propagation reduces the detectability of magnetic anomalies. Finally, we derive an asymptotic formula valid for the long leading wave that travels ahead of the dispersive group over transoceanic distances. This formula holds promise for the rapid assessment of tsunami risk. These findings advance fundamental understanding and may inform the development of future tsunami early warning systems relying on magnetic field detection.

We study transverse profiles and time fluctuations of turbulence dissipation rate, turbulence kinetic energy and integral length scales by means of high-speed stereoscopic particle image velocimetry in the turbulent wake of a 6 : 1 prolate spheroid that has its principal axis aligned with the incoming non-turbulent flow. This turbulent wake of a slender body differs from turbulent bluff body wakes in terms of transverse non-homogeneity of turbulence dissipation rate and because it is not axisymmetric even though it nominally is. Even so, both transverse profiles and time fluctuations of turbulence dissipation rate coefficients (inverse ratio between the rate with which the large scales lose energy and the rate with which the small scales dissipate energy) and of the Taylor length-based Reynolds number (ratio between the turbulent kinetic energy mostly in the large scales and the turbulent kinetic energy at the smallest scales) obey self-regulating non-equilibrium, as previously found in various other turbulent flows. However, the power law relating the transverse variations and the time fluctuations of these two ratios differs from previously reported self-regulating non-equilibrium power law scalings in other turbulent flows.

The coupling between Rayleigh–Taylor (R–T) and Saffman–Taylor (S–T) instabilities, when a gas displaces a high-viscosity liquid, remains challenging to elucidate due to the unclear roles of density and viscosity contrasts. Counterintuitively, our radial Hele-Shaw cell experiments revealed that viscosity contrast – typically considered a damping factor – serves as the primary driver of instability. We observed that the glycerin–air interface, despite its higher viscosity, exhibits significantly greater instability than the water–air interface. This anomalous behaviour arises from the S–T mechanism, which accelerates the onset of nonlinearity and induces an early transition to fingering. We applied a unified model to decouple the competing influences of surface tension oscillation and viscous damping on R–T instability and the S–T destabilisation. Moreover, we proposed criteria for either mostly enhancing or completely freezing the instability. These findings offer valuable insights into manipulating hydrodynamic instabilities in contracting/expanding geometries through surface tension and viscosity.