Turbulence is often treated as memoryless. Once the forcing and control parameters are fixed and after any transients have decayed, the system settles into a unique, statistically stable turbulent state. A growing body of work shows that this paradigm does not have to be true. Even under identical forcing and boundary conditions, turbulent flows may sustain multiple long-lived structures, each with its own characteristic transport properties and fluctuations. The paper by Yao et al. (2026 J. Fluid Mech., vol. 1030, R4) demonstrates this phenomenon particularly clearly for centrifugal convection, where the flow self-organises into different numbers of coherent rolls depending on the initial conditions. Beyond reporting the observation of multiple flow states, they provide a theoretical explanation as to why only certain flow states can exist and why the range of possible multiple states shrinks as turbulence intensifies.

This article offers a critical literature review on the debate on constitutional identity, combining a synthesis of existing literature with a critical reframing of the concept’s theoretical and methodological foundations. While constitutional identity has become increasingly prominent in legal and political debates – particularly within the European Union – its meanings and functions remain contested. The article develops a typology of approaches to constitutional identity, distinguishing two main strands. First, it examines constitutional identity as a legal doctrinal notion. In this sense, identity can function either as a static concept – anchored in an unchanging normative core that limits political or legal interference – or as a dynamic concept, shaped through interactions between domestic constitutional orders and external legal ideas and practices. Second, the article turns to the descriptive use of constitutional identity, understood as a way to explain how a political community understands itself through its constitution. This part surveys key philosophical debates, including how constitutional identity negotiates sameness and difference, how it evolves over time, how it relates to competing conceptions of the constitutional subject, and how it is constructed through narrative, symbolism, and social practice. The article concludes by arguing that if constitutional identity is not a fixed essence but a dialogical and constructed assemblage of identities, then its study must go beyond the legal domain. It calls for a deepening of the interdisciplinary research agenda that includes insights from philosophy, sociology, discourse theory, and literary studies.

The present study aimed to explore sleep diary-derived parameters and sleep measures as mediators of the effects of the Transdiagnostic Intervention for Sleep and Circadian Dysfunction (TSC) on psychological outcomes. A secondary analysis of a two-arm randomized controlled trial of a group-based TSC for major depressive disorder was conducted. The participants included 152 adults (mean age = 34.0; 79.6% female) who were randomized into either the TSC or care-as-usual group. Mediation analysis indicated that reduction in insomnia symptom severity (standardized indirect effects: −0.06 to −0.17), sleep disturbance (−0.04 to −0.22), and sleep-related impairment (−0.04 to −0.17) was significantly mediated by sleep diary-derived sleep parameters. The treatment effects on depressive symptoms (standardized indirect effects: −0.05 to −0.10), anxiety symptoms (−0.04 to −0.07), fatigue (−0.05 to −0.09), functional impairment (−0.06 to −0.09), and quality of life (0.04 to 0.08) were sequentially mediated by sleep parameters and insomnia symptom severity. However, the severity of insomnia symptoms alone (magnitudes of standardized indirect effects: 0.09–0.17) but not sleep parameters alone (0.00–0.07) mediated the treatment effects on psychological outcomes, indicating that sleep parameters need to influence subjective sleep measures to sequentially affect psychological outcomes. These results underscore the critical roles of subjective sleep measures in clinical improvements within a sleep-targeted intervention.

This paper examines relationships between AI occupational exposure and workforce patterns in U.S. federal agencies from 2019–2024. Using administrative employment data, we document systematic associations between agencies’ concentrations of AI-exposed occupations and employment dynamics. Agencies with higher AI exposure exhibit declining routine employment shares, expanding expert roles, and wage compression effects. We develop a theoretical framework incorporating institutional constraints distinguishing public organisations: employment protections, standardised compensation systems, and political oversight. The model features strategic interactions between budget-maximising directors and electoral-sensitive overseers, predicting workforce evolution under institutional constraints. Our identification exploits fixed occupational exposure scores, so observed changes in agency-level exposure reflect workforce composition shifts rather than measurement artefacts. Patterns suggest agencies with greater AI-susceptible occupations experience reallocation rather than displacement, providing insights for understanding technological change in institutionally constrained environments and informing governance frameworks balancing modernisation with democratic accountability.