The causal relevance of local flow conditions in open-channel turbulence is analysed using ensembles of interventional experiments in which the effect of perturbing the flow within a small cell is monitored at some future time. When this is done using the relative amplification of the perturbation energy, causality depends on the flow conditions within the cell before it is perturbed, and can be used as a probe of the flow dynamics. The key scaling parameter is the ambient shear, which is also the dominant diagnostic variable for wall-attached perturbations. Away from the wall, the relevant variables are the streamwise and wall-normal velocities. Causally significant cells are associated with sweeps that carry the perturbation towards the stronger shear near the wall, whereas irrelevant ones are associated with ejections that carry it towards the weaker shear in the outer layers. Causally significant and irrelevant cells are themselves organised into structures that share many characteristics with classical sweeps and ejections, such as forming spanwise pairs whose dimensions and geometry are similar to those of classical quadrants. At the wall, this is consistent with causally significant configurations in which a high-speed streak overtakes a low-speed one, and causally irrelevant ones in which the two streaks pull apart from each other. It is argued that this is probably associated with streak meandering.

Across Latin American countries, there is remarkable heterogeneity in abortion legislation, ranging from full prohibition to legal elective abortion.1 However, abortion policy does not seem to clearly map onto implementation on the ground. On the one hand, even in countries with very restrictive abortion laws, (clandestine) abortion rates are comparatively high, and legislation that criminalizes abortion is rarely enforced (Blofield 2006; Htun 2003). On the other hand, in countries that allow abortion under all or some circumstances, access to abortion is not guaranteed. In Argentina, for instance, different reports have stressed the difficulty in accessing abortion procedures both before and after legalization was enacted in early 2021.2

In vitro production of porcine embryos is a complicated process that includes in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC). Insufficient cytoplasmic maturation, slow zona reaction and improper embryo culture conditions will compromise the efficiency of porcine embryo production in vitro. Previous studies have shown that insulin-transferrin-selenium (ITS) in IVM or IVC medium could improve porcine oocyte maturation, decrease polyspermy fertilization and promote subsequent embryonic development in vitro. However, the effect of ITS both in IVM and IVC media on porcine embryo production in vitro hasn’t been elucidated. In this study, we found that 1.0% ITS supplementation in IVM/IVC media promoted the expansion of cumulus cells, raised mitochondrial membrane potential, increased ATP content and reduced ROS level in matured oocytes, improved blastocyst rate and the cell number of blastocyst, simultaneously. In conclusion, the IVM/IVC media supplemented with 1.0% ITS can improve the efficiency of porcine embryo production in vitro.

The behaviour of mountain glaciers on decadal time scales is a useful indicator for assessing climate change. Although less monitored and studied than the ice sheet, local glaciers and ice caps along the coast of Greenland are substantial contributors to meltwater runoff and sea level rise. This study analyses the cumulative area, ice mass and Equilibrium Line Altitude (ELA) change that occurred on 4100 glaciers and ice caps in West Greenland from 1985 to approximately 2020, using remotely sensed data and including glaciers smaller than 1 km2 in the calculations. The glaciers involved in the study decreased in area by 1774 ± 229 km2 which corresponds to almost −15%. Their surface elevation decreased on average by 20.6 ± 3.9 m, corresponding to a rate of −0.5 ± 0.1 m w.e. a−1. The ELA shows a median regional rise of 150 m with marked local variability and higher median rise in the northern part of the study area. Strong regional gradients in ELA of individual glaciers are found, both towards the ice sheet and in areas where local orography affects precipitation. The observed high spatial variability of changes suggests that more monitoring on sub-regional level is needed.

Many real-world intertemporal decisions involve a group of two or more individuals making consensual decisions through group collaboration. Here, we ask how group collaboration affects intertemporal choices. In two experiments, participants completed intertemporal choices individually first (the precollaboration phase). Then, participants were placed into groups of two or three and completed a similar intertemporal task, with the group arriving at a consensual decision on each trial (the group collaboration phase). Finally, participants once again completed the intertemporal choices individually (the postcollaboration phase). Results showed that after group collaboration, the delay discounting significantly decreased compared to before collaboration both at group level and at individual level. The effect of group collaboration on individual intertemporal choices was no longer discernible by 1 week later. Therefore, the current research demonstrates the effectiveness of group collaboration and provides a way to nudge both groups and individuals to make farsighted choices.

A model is formulated of a two-dimensional migrating, or swimming, inviscid bubble in a viscous fluid whose unsteady displacement is caused by the spreading over its surface of an initial distribution of insoluble surfactant. Assuming small capillary and Reynolds numbers, and a linear equation of state giving the surface tension as a function of surfactant concentration, the quasi-steady Stokes flow around the bubble is found analytically and explicit formulas are determined for the time-dependent bubble speed and its final overall displacement. At infinite surface Péclet number this is done using a complex version of the method of characteristics to solve a complex partial differential equation of Burgers type. For a finite non-zero surface Péclet number, the problem is shown to be linearizable by a complex variant of the classical Cole–Hopf transformation. The formulation allows general statements to be made on the bubble speed and its total net displacement in terms of the initial surfactant distribution. A weak finite-time singularity in the surface activity associated with an isolated clean point on the bubble surface is also identified and studied in detail.

This article examines recent measures undertaken by major commercial banks to mitigate and address human rights risks associated with their financial dealings in the arms industry. By reviewing the corporate policies of 20 leading banks that provide financing to top arms manufacturing and exporting companies, the article provides insights into three significant aspects of banks’ efforts: the development of defence sector policies, the implementation of risk assessments for adverse human rights impacts, and the application of exclusion clauses. These measures highlight the increasing recognition by banks of the need to address the ethical, social and human rights implications of financing arms deals, contributing to the broader regulatory and normative framework governing the arms industry.

New limit theory is provided for a wide class of sample variance and covariance functionals involving both nonstationary and stationary time series. Sample functionals of this type commonly appear in regression applications and the asymptotics are particularly relevant to estimation and inference in nonlinear nonstationary regressions that involve unit root, local unit root, or fractional processes. The limit theory is unusually general in that it covers both parametric and nonparametric regressions. Self-normalized versions of these statistics are considered that are useful in inference. Numerical evidence reveals interesting strong bimodality in the finite sample distributions of conventional self-normalized statistics similar to the bimodality that can arise in t-ratio statistics based on heavy tailed data. Bimodal behavior in these statistics is due to the presence of long memory innovations and is shown to persist for very large sample sizes even though the limit theory is Gaussian when the long memory innovations are stationary. Bimodality is shown to occur even in the limit theory when the long memory innovations are nonstationary. To address these complications, new self-normalized versions of the test statistics are introduced that deliver improved approximations that can be used for inference.

According to conventional wisdom, a great power engaging in international retrenchment regularly incurs tremendous costs. Following its withdrawal from a commitment abroad, the argument goes, windows of opportunity emerge that rivals exploit to their benefit, thus imposing significant costs on the retrenching great power. I argue that pundits and policymakers consistently overestimate the dangers associated with strategic withdrawals: great powers can – and in the past frequently have – successfully engaged in international retrenchment without creating opportunities for their rivals to gain significant strategic benefits. To make this case, I develop a new typology of international retrenchment strategies based on the kind and degree of disengagement they entail and demonstrate that most types do not regularly pave the way for rival gains. I support my argument through a series of plausibility probes: the Soviet retrenchment from Romania in the 1950s; the US retrenchment from Korea in the 1970s; and the US retrenchment from Western Europe in the 1990s.

In this paper, we establish a new version of one-dimensional discrete improved Hardy’s inequality with shifts by introducing a shifting discrete Dirichlet’s Laplacian. We prove that the general discrete Hardy’s inequality as well as its variants in some special cases admit improvements. Further, it is proved that two-variable discrete $p$-Hardy inequality can also be improved via improved discrete $p$-Hardy inequality in one dimension. The result is also extended to the multivariable cases.

In this article, we consider some critical Brézis-Nirenberg problems in dimension $N \geq 3$ that do not have a solution. We prove that a supercritical perturbation can lead to the existence of a positive solution. More precisely, we consider the equation:

\begin{equation*}\left\{\begin{array}{rllll}-\Delta u & = & \lambda u^{q-1} + u^{2^*+ r^\alpha -1} & \mbox{in} & B, \\u & \gt & 0 & \mbox{in} & B, \\u&=&0 & \mbox{on} & \partial B,\\\end{array}\right.\end{equation*}

$B \subset \mathbb{R}^N$

$N\geq 3$

$r=\vert x \vert$

$\alpha \in (0,\min\{N/2,N-2\})$

$q\in [2,2^*]$

$r \in (0,1)$

This study investigates the flow structures and combustion regimes in an axisymmetric cavity-based scramjet combustor with a total temperature of 1800 K and a high Reynolds number of approximately 1 × 107. The hydroxyl planar laser-induced fluorescence technique, along with the broadband flame emission and CH* chemiluminescence, is employed to visualize the instantaneous flame structure in the optically accessible cavity. The jet-wake flame stabilization mode is observed, with intense heat release occurring in the jet wake upstream of the cavity. A hybrid Reynolds-averaged Navier–Stokes/large-eddy simulation approach is performed for the 0.18-equivalent-ratio case with a pressure-corrected flamelet/progress variable model. The combustion regime is identified mainly in the corrugated or wrinkled flamelet regime (approximately 102 < Da < 104, 103 < Ret < 105 where $Da$ is the Damköhler number and $Re_t$ is the turbulent Reynolds number). The combustion process is jointly dominated by supersonic combustion (which accounts for approximately 58 %) and subsonic combustion, although subsonic combustion has a higher heat release rate (peak value exceeding 1 × 109 J (m3s)−1). A partially premixed flame is observed, where the diffusion flame packages a considerable quantity of twisted premixed flame. The shockwave plays a critical role in generating vorticity by strengthening the volumetric expansion and baroclinic torque term, and it can facilitate the chemical reaction rates through the pressure and temperature surges, thereby enhancing the combustion. Combustion also shows a remarkable effect on the overall flow structures, and it drives alterations in the vorticity of the flow field. In turn, the turbulent flow facilitates the combustion and improves the flame stabilization by enhancing the reactant mixing and increasing the flame surface area.

During oscillatory wetting, a phase retardation emerges between contact angle variation and contact line velocity, presenting as a hysteresis loop in their correlation – an effect we term dynamic hysteresis. This phenomenon is found to be tunable by modifying the surface with different molecular layers. A comparative analysis of dynamic hysteresis, static hysteresis and contact line friction coefficients across diverse substrates reveals that dynamic hysteresis is not a result of dissipative effects but is instead proportionally linked to the static hysteresis of the surface. In the quest for appropriate conditions to model oscillatory contact line motion, we identify the generalized Hocking's linear law and modified generalized Navier boundary condition as alternative options for predicting realistic dynamic hysteresis.

This article compares China’s stance during the UNCLOS negotiations – the starting point of contemporary law of the sea, with its engagement in the latest development of negotiations on the United Nations agreement on biodiversity beyond national jurisdiction (BBNJ). It answers the question, how does China participate in these two important rules-making processes of the international law of the sea? By identifying salient positions China took in each set of lengthy negotiations and explaining the reasons behind, the article also aims to reflect what a rising China may bring to the international legal maritime order in the foreseeable future. The first part of this article, on the nature of China’s engagement in the UNCLOS negotiations, draws on archival study of official records of the UNCLOS III (1973–1982), as has been digitalized by the UN Office of Legal Affairs. The second part examines the period between the adoption of the UNCLOS (1982) and the start of the BBNJ process (2004), paying attention to China’s shifting practice towards the exploration and exploitation of the deep seabed mineral resources, and its concerns over the ratification of the UNCLOS and the 1995 FSA. Then the article focuses on China in the BBNJ negotiations – Working Groups, Preparatory Committee Meetings and Intergovernmental Conferences. Drawing upon the evolution of China’s positions over the past five decades, the article concludes with some insights on the likely future directions and implications of China’s engagement with the international law of the sea.