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Scholars have identified several temporal challenges in foreign policymaking, such as variable time horizons and maintaining commitment or resolve over time. While the behavioural turn has emphasised leaders and their subjective perceptions, research often relies on rationalist conceptions of objective and linear time and struggles to assess leaders’ subjective perceptions of it. This paper theorises time as an intrinsic aspect of narrative reasoning in foreign policy, introducing a ‘temporal definition of the situation’ (TDoS) framework to capture leaders’ situation-specific subjective time perceptions. I then operationalise the TDoS framework’s key temporal features and show how it can be empirically examined. The value of the TDoS is illustrated by assessing the temporal perceptions of Bush and Obama regarding Iran’s nuclear programme, showing how their distinct definitions of the foreign policy situation shaped their subjective time perceptions and their corresponding responses. I conclude by discussing how this advancement can enhance behavioural research, provide insights into the ‘why now?’ questions surrounding leaders’ actions, and challenge existing understandings of time’s impact on foreign policymaking.
In this study, we obtain the continuum equations of Arctic sea ice motion starting from the dynamics of a single floe and show that the rheology that emerges from floe–floe interactions is viscous – as conjectured by Reed and Campbell (J. Geophys. Res., vol. 67 (1), 1962, pp. 281–297). The motion of the floe is principally driven by the wind and ocean currents and by inelastic collisions with the neighbouring floes. A mean-field representation of these collisions is developed, neglecting any changes in the floe thickness due to thermal growth and mechanical deformation. This mean-field representation depends on the state of the ice cover, and is expressed in terms of ice concentration and mean thickness. The resulting Langevin equation for the floe velocity, or the corresponding kinetic equation (Kramers–Chandrasekhar equation (KCE)) for its probability density, provides a complete description of the floe’s motion. We then use the floe-scale dynamics to obtain a continuum description of sea ice motion through a Chapman–Enskog analysis of the KCE. The local equilibrium solution to the kinetic equation is found to be the Laplace distribution, in qualitative agreement with observations. Our approach also allows us to establish the dependence of pressure and shear viscosity of the ice cover on ice concentration and mean thickness. Lastly, we show that our results resolve a conflict associated with the choice of the value of shear viscosity in previous idealised numerical studies of Arctic sea ice motion.
Previous studies claimed that the non-monotonic effects of wettability came mainly from the heterogeneity of geometries or flow conditions on multiphase displacements in porous media. For macroscopic homogeneous porous media, without permeability contrast or obvious preferential flow pathways, most pore-scale evidence showed a monotonic trend of the wettability effect. However, this work reports transitions from monotonic to non-monotonic wettability effects when the dimension of the model system rises from two-dimensional (2-D) to three-dimensional (3-D), validated by both the network modelling and the microfluidic experiments. The mechanisms linking the pore-scale events to macroscopic displacement patterns have been analysed through direct simulations. For 2-D porous media, the monotonic effect of wettability comes from the consistent transition pattern for the full range of capillary numbers $Ca$, where the capillary fingering mode transitions to the compact displacement mode as the contact angle $\theta$ decreases. Yet, it is indicated that the 3-D porous geometries, even though homogeneous without permeability contrast or obvious preferential flow pathways, introduce a different $Ca$–$\theta$ phase diagram with new pore-scale events, such as the coupling of capillary fingering with snap-off during strong drainage, and frequent snap-off events during strong imbibition. These events depend strongly on geometric confinements and capillary numbers, leading to the non-monotonicity of wettability effects. Our findings provide new insights into the multiphase displacement dependent on wettability in various natural porous media and offer design principles for engineering artificial porous media to achieve desired immiscible displacement behaviours.
Composer-Performer Collaboration (CPC) has become a distinct research field in the last twenty years. This article explores a long letter written by Justin Connolly to Neil Heyde in place of final workshops for Collana, for solo cello. The letter sheds forensic light on Connolly’s musical vision and approach to collaboration, revealing a distinctive combination of pedantic concern for details (with concomitant precision of notation) and great flexibility. Connolly encourages the performer as an active participant, with responsibility for a ‘parallel universe of discourse’. Heyde responds directly to extracts from the letter and outlines the shared working context. Connolly’s letter confirms the significance of the dimensions of notation, gesture and instrumental choreography that have emerged in the CPC literature but affords a perspective not shaped by academic demand characteristics. It presents an especially sophisticated approach to what recent writing has called empathetic embodiment.
Do developing-country democracies continue to struggle with revenue loss post-trade liberalization? This article revisits the evidence presented in Democracies in Peril and confirms that, despite critiques suggesting otherwise, a substantial revenue shock persists following tariff reductions, and democracies in less developed countries (LDCs) remain particularly vulnerable. Drawing on updated data from the World Development Indicators and supplemental checks with the International Centre for Tax and Development database, we show that democracies have lagged behind non-democracies in compensating for lost trade tax revenues—even after reforms aimed at expanding income taxes and value-added taxes. In addition to emphasizing ongoing domestic political obstacles in liberalizing democracies, we examine emerging challenges that impede revenue generation in LDCs. We conclude with suggested directions for future research on the politics of revenue generation in LDC democracies, emphasizing how improvements in public goods provision and global tax initiatives could help to end the downward cycle in revenue generation.
This study utilises large-eddy simulation with the actuator line model to examine the effects of the tip speed ratio (TSR) on the wake-meandering characteristics of a wind turbine in uniform and turbulent inflows. It is shown that as the TSR grows, the onset position of the wake meandering moves closer to the rotor, and the magnitude of wake oscillation is stronger. This aligns with previous work showing that a higher TSR can accelerate the instability and breakdown of tip vortices. Without a nacelle, the Strouhal number of the wake meandering is found to be independent of the TSR under both the uniform and turbulent inflows. However, with a relatively large nacelle, the Strouhal number first increases and then decreases with TSR. Therefore, the current discovery elucidates the crucial role of the nacelle and clarifies the origin of the TSR dependence of the Strouhal number in wake meandering. In addition, the characteristic frequency of the wake meandering under the turbulent inflow is much smaller than that under the uniform inflow, because of the significant influence of the freestream turbulence. Furthermore, the proper orthogonal decomposition (POD) and spectral POD (SPOD) methods are employed to study the spatiotemporal characteristics of the meandering wake and its TSR dependence. It is found that the tip and root vortices are the prominent wake structures under the uniform inflow, whereas more complex multiscale structures from the interaction between the freestream turbulence and tip/root vortices exist under the turbulent inflow. Moreover, an amplitude modulation phenomenon of the POD time coefficients at the optimal TSR is observed in the uniform inflow case. Finally, a reduced-order model is constructed for predicting the wake dynamics by combining the SPOD and the ‘sparse identification of nonlinear dynamics’ algorithm with high accuracy and interpretability.
There has been recurrent agitation for external self-determination by most of the South-East people of modern Nigeria through the secessionist group the Indigenous People of Biafra (IPOB). This agitation reached crisis point in 2015 with military action which escalated into a violent confrontation, in which the IPOB claimed some of their members were killed. The IPOB’s request for external self-determination fell on deaf ears, however, the counter-claim being that Nigerian territorial integrity cannot be compromised. This article examines the right to self-determination under international law and in the African system, as well as the types of this right that have been identified by scholars and whether the IPOB’s call can be justified. It argues that the type of self-determination sought by the IPOB and the manner in which they seek it may not be attainable under international law, except through a consensus-based process between the Nigerian government and the South-East people of Nigeria.
A widely esteemed and decorated scholar who currently directs the Gotha Research Centre at the University of Erfurt, where he is also Professor in the Cultures of Knowledge in Modern Europe, Martin Mulsow has been working for over two decades to better understand the early modern origins of contemporary European thought. The Hidden Origins of the German Enlightenment, his most recent English publication, is best understood as the latest installment in what is already a three-volume history of the origins of the German Enlightenment. He indicates here that a fourth book has already been finished in German and awaits translation and publication in English in the manner of his other books in this series. The bibliography lists over sixty publications authored by Mulsow, and while his work does not appear to be finished, his recent books in English mark the apex of a scholarly arc that is noteworthy for its persistent questioning of familiar interpretive paradigms and an insistent drive to offer new insights into the origins and dynamics of European Enlightenment history.
The evidence for an upwelling in small donor contributions is evident not just in response to presidential and congressional campaigns, but in statewide elections as well. The general question for this vein of research is whether growth in the donorate contributing $200 or less can be detected in states that would neither be considered hotly competitive battlegrounds nor especially visible in national party politics in terms of size or media attention. Specifically, we gather and examine campaign contribution records for individuals extending back to the early 2000s for Washington State gubernatorial contests. Given that this state has a low ceiling on total campaign contributions to state and local candidates ($2,400 per cycle for governor, $1,200 for state legislative and local offices), there is reason to expect an increasing reliance on small donors as campaign costs have risen. Unlike states with no campaign contribution limits on individuals (e.g., Texas, Pennsylvania, Oregon), candidates in the Evergreen State must go to more donors to raise the same large sums. An important related question is whether the parties are relying on the same locales to harvest small donations that they have traditionally relied upon for larger ones. We see that even in a state that would be considered out of the glare of the national spotlight, the small donor surge is democratizing campaign finance by spatially diffusing financial support. These developments fuel social science curiosity about the causes and effects of these new patterns of participation.