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A stable-set bound and maximal numbers of Nash equilibria in bimatrix games
No full textQuint and Shubik conjectured that a nondegenerate [Formula: see text] game has at most [Formula: see text] Nash equilibria in mixed strategies. The conjecture is true for [Formula: see text] but false for [Formula: see text]. We answer it positively for the remaining case [Formula: see text], which had been open since 1999. The problem can be translated to a combinatorial question about the vertices of a pair of simple n-polytopes with 2n facets. We introduce a novel obstruction based on the index of an equilibrium, which states that equilibrium vertices belong to two equal-sized disjoint stable sets of the graph of the polytope. This bound is verified directly using the known classification of the 159,375 combinatorial types of dual neighborly polytopes in dimension five with 10 facets. Nonneighborly polytopes are analyzed with additional combinatorial techniques where the bound is used for their disjoint facets. Funding: This work was supported by the Deutsche Forschungsgemeinschaft Priority Program “Combinatorial Synergies” [Grant 539847176]
Healthcare gaps and inequities following hospitalisation for COVID-19 in Brazil’s universal healthcare system: a patient-engaged survey of Long COVID healthcare needs, use and barriers
No full textBackground Long COVID (LC) is an infection-associated chronic condition (IACC) that tends to be neglected by healthcare systems. Studies of post-COVID healthcare utilisation find elevated levels of use but have mainly been conducted in high-income settings. In the context of Brazil’s universal health system (SUS), our patient-engaged study aimed to map healthcare needs, use, and access barriers related to LC up to 24 months following COVID-19 hospitalisation, in the interest of informing health system planning for an equitable LC response. Methods A cohort survey included a probabilistic sample of hospitalised COVID-19-confirmed individuals aged ≥ 18, who had been discharged from public hospitals in Rio de Janeiro between December 2020 and November 2022. Socio-demographic and clinical data were collected, including self-reported LC symptoms, self-reported LC, healthcare needs, use, and access barriers. Results In a sample of 556 participants, corresponding to an estimated population of 11,328 individuals, 50.0% (95%CI 44.3–55.6%) reported healthcare needs in the six months prior, due to new-onset or worsened conditions after COVID-19. Almost 45.0% did not complete high school, while 26.5% lived below the poverty line (~ US1,500 or ~ US$250) were more likely to have accessed specialised medical care. Conclusions The SUS is not meeting the high need for LC healthcare, raising concerns about deepening health inequities. In Brazil, as elsewhere, LC joins other IACCs in becoming an invisibilised epidemic, with LC patients, especially those unable to pay for care, neglected amid general healthcare backlogs. A comprehensive pandemic response must include dedicated efforts to surveil and treat the long-term impacts of infection
Identifying with political actions plays a greater role in predicting collective action intention among the advantaged than identifying with political opinions
No full textThis research aims to investigate what motivates members of advantaged groups to join collective action efforts aimed at reducing discrimination, as understanding this motivation is crucial for designing effective interventions and campaigns that aim to mobilise these groups in the fight against discrimination. Across three studies conducted in Germany (NStudy 1 = 326; NStudy 2 = 136) and the UK (NStudy 3 = 184), we investigated the psychological mechanisms linking moral conviction to collective action intention among members of advantaged groups. Each study focused on a distinct social issue: xenophobia, sexism, and racism. Specifically, we examined the mediating roles of different types of politicised identification (solidarity-based and opinion-based), perceived collective efficacy, and perceived closeness with discriminated groups. Results consistently showed that solidarity-based identification was a stronger and more reliable predictor of collective action intention than collective efficacy, closeness with discriminated individuals, or opinion-based identification. By focusing on solidarity-based identification, social movements can better harness the potential of these groups to contribute to meaningful social change, thereby enhancing the overall effectiveness of efforts to combat xenophobia, sexism, and racism
A bioenergy blueprint for Kuwait: regional research insights, waste valorisation, feasibility and policy pathways
No full textKuwait faces mounting pressure to diversify its energy mix, reduce its dependency on landfills, and meet climate targets under Vision 2035. Despite producing over 2.6 million tonnes of organic waste annually, including food and agricultural residues, sewage, and petroleum sludge, bioenergy currently remains absent from Kuwait’s energy portfolio. This paper makes a case for anaerobic digestion (AD) as a strategic enabler of Kuwait’s low-carbon transition. Regional bibliometric analysis reveals Kuwait’s peripheral role in Middle Eastern bioenergy research, characterised by limited collaboration and a lack of thematic leadership. Building on this, the study models a technoeconomic scenario for treating 50% of Kuwait’s organic waste via AD, estimating 394 Gigawatt hours (GWh) of renewable electricity annually, 197,538 tonnes of CO₂-equivalent emissions avoided, and over $1.81 billion in profit over 20 years. A comparative framework highlights the fiscal and environmental superiority of AD over landfilling. The findings are translated into a policy roadmap that emphasises pricing reform, integration of the circular economy, public-private investment, and alignment of science and policy. AD offers Kuwait the opportunity to transform waste into renewable assets, enhance energy security, meet climate goals, and lead in regional sustainability
The Motheral Report and land reform in Iran, 1952-1963
No full textIn 1957, Shah Mohammad Reza Pahlavi commissioned US agricultural economist Joseph R. Motheral to study Iran’s land tenure system and propose reforms. The resulting Motheral Report laid the foundation for later land redistribution programs, which sought to address, through rural development, the issue of political instability. The report drew upon the Shah’s pre-existing objectives and efforts to advocate for US support in implementing large-scale land reform, including financial assistance and technical training, and outlined a five-year timeline for redistribution. While the report failed to spur immediate action, its key points shaped subsequent efforts by both the US and Iranian governments, including Prime Minister Ali Amini’s land reform efforts in 1961 and the Shah’s White Revolution in 196
Extending dialogues on the urban
No full textAcross the different vernaculars of the world's urban majorities, there is renewed bewilderment as to what is going on in the cities in which they reside and frequently self-build. Prices are unaffordable and they are either pushed out or strongly lured away from central locations. Work is increasingly temporary, if available at all, and there is often just too much labour involved to keep lives viably in place. Not only do they look for affordability and new opportunities in increasingly distant suburbs and hinterlands, but for orientations, for ways of reading where things are heading, increasingly hedging their bets across multiple locations and affiliations. Coming together to write this piece from our own multiple orientations, we are eight researchers who, over the past year, joined to consider how variegated trajectories of expansion unsettle the current logic of city-making. We have used the notion of extensions as a way of thinking about operating in the middle of things, as both a reflection of and a way of dealing with this unsettling. An unsettling that disrupts clear designations of points of departure and arrival, movement and settlement, centre and periphery, and time and space
The impact of loneliness on healthcare costs and service utilisation and the cost-effectiveness of loneliness interventions: systematic review
No full textBackground: Loneliness is associated with several physical and mental health problems, yet its costs to the healthcare system remain unclear. Aims: The current study aimed to review literature on the health and social care impacts of loneliness, and review economic evaluations of loneliness interventions. Method: We conducted a systematic review of studies published from 2008 to April 2025 by searching five bibliographic databases, grey literature and reference lists of systematic reviews. Studies estimating health and social care cost/expenditure, and on health resource utilisation, were included to assess the impact of loneliness on the health system. Return on investment, social return on investment and cost-effectiveness evaluations were included to assess the economic impact of loneliness interventions. We conducted quality appraisal and narrative synthesis of results. Results: We included 53 studies. Eight estimated the healthcare cost/expenditure of loneliness, 33 reported healthcare resource use and 19 were economic evaluations of interventions. Findings relating to the cost/expenditure of loneliness and service use were inconsistent: some studies reported excess costs/expenditure and service use, whereas others found lower costs/expenditure and service use. Economic evaluation studies indicated that loneliness interventions can be cost-effective, but were not consistently cost-saving or effective in reducing loneliness. Conclusions: Findings on the impact of loneliness on the healthcare system and economic evaluations of loneliness interventions were varied. Therefore, we cannot derive confident conclusions from this review. To address evidence gaps, future research relating to social care, younger populations, direct healthcare costs of loneliness and randomised controlled trials with long-term follow-ups should be prioritised
What the ‘Global South’ wants: necessary reforms to the international trade and financial architecture
No full textThere has been a debate underway in international affairs about the term “Global South” and what it is, who it is, and what it wants, and if the term is even useful or not. This paper explores this debate, examines the history and meaning of the term “Global South,” and lists many of the things that the Global South wants from the rich countries in terms of reforms to the international financial and trade architecture, including: enabling developing countries to pay for imports with their domestic currencies; establishing a more balanced global trading system; enabling developing countries to borrow in their own domestic currencies; establishing to get an immediate international resolution to the worsening sovereign debt crisis an international sovereign debt restructuring mechanism for heavily-indebted countries; IMF and World Bank policy and governance reforms; WTO policy and governance reforms; greater access to international financing during financial crises and for tackling climate change; improved technology transfer; reforms to bilateral trade and investment agreements and international investment arbitration procedures; subsidies to support green energy transitions; taxation of cross-border e-commerce; reforms of the major credit rating agencies; reducing tax evasion and other illicit financial flows; and easing restrictions on the use of capital controls
Bonus question: how does flexible incentive pay affect unemployment dynamics?
No full textWe introduce dynamic incentive contracts into a model of unemployment fluctuations. Our main result is that wage cyclicality from incentives does not affect the response of unemployment to productivity shocks. The response of unemployment is the same, to a first-order, in two economies: one with flexible incentive pay, and another with exogenously fixed wages. This equivalence is due to movements in effort. Under the optimal incentive contract, firms’ profits do not change when wages fall, because the effort of the worker falls too
Solar wind magnetohydrodynamic turbulence energy transfer rate ordered by magnetic field topology
No full textThe magnetic field fluctuations that mediate a magnetohydrodynamic turbulent cascade have distinct magnetic topologies and associated energy transfer rates. Magnetic field topology is classified by the magnetic field gradient tensor constructed from solar wind in situ observations by the four Cluster spacecraft tetrahedron on a scale of ∼40 proton gyroradii. Energy transfer rates are estimated instantaneously from the third-order term. We find on average 25% and up to 60% larger forward energy transfer rates in hyperbolic topology compared to flux ropes/plasmoids. Hyperbolic topology, consistent with reconnection, preferentially contributes to the forward energy cascade in magnetohydrodynamic turbulence in the solar wind. This forward cascade is a candidate mechanism for heating the solar wind