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Revolutionary movements operated underground before and after national independence in many African countries. A communist party in Burkina Faso, the Parti communiste révolutionnaire voltaïque (PCRV), continued its underground political practice, despite democratic breakthrough. On the basis of long-term research engagement on popular struggle and the fight against impunity, the author used participant observation in street marches, meetings, sit-ins, and so on, and text analysis of pamphlets, declarations, and tracts to analyze how the PCRV is present in anti-imperialist struggles, while being absent in the public sphere.
Underwater robots conducting inspections require autonomous obstacle avoidance capabilities to ensure safe operations. Training methods based on reinforcement learning (RL) can effectively develop autonomous obstacle avoidance strategies for underwater robots; however, training in real environments carries significant risks and can easily result in robot damage. This paper proposes a Sim-to-Real pipeline for RL-based training of autonomous obstacle avoidance in underwater robots, addressing the challenges associated with training and deploying RL methods for obstacle avoidance in this context. We establish a simulation model and environment for underwater robot training based on the mathematical model of the robot, comprehensively reducing the gap between simulation and reality in terms of system inputs, modeling, and outputs. Experimental results demonstrate that our high-fidelity simulation system effectively facilitates the training of autonomous obstacle avoidance algorithms, achieving a 94% success rate in obstacle avoidance and collision-free operation exceeding 5000 steps in virtual environments. Directly transferring the trained strategy to a real robot successfully performed obstacle avoidance experiments in a pool, validating the effectiveness of our method for autonomous strategy training and sim-to-real transfer in underwater robots.
Knowledge of the status of ecosystems is vital to help develop and implement conservation strategies. This is particularly relevant to the Arctic where the need for biodiversity conservation and monitoring has long been recognised, but where issues of local capacity and logistic barriers make surveys challenging. This paper demonstrates how long-term monitoring programmes outside the Arctic can contribute to developing composite trend indicators, using monitoring of annual abundance and population-level reproduction of species of migratory Arctic-breeding waterbirds on their temperate non-breeding areas. Using data from the UK and the Netherlands, countries with year-round waterbird monitoring schemes and supporting relevant shares of Arctic-breeding populations of waterbirds, we present example multi-species abundance and productivity indicators related to the migratory pathways used by different biogeographical populations of Arctic-breeding wildfowl and wader species in the East Atlantic Flyway. These composite trend indicators show that long-term increases in population size have slowed markedly in recent years and in several cases show declines over, at least, the last decade. These results constitute proof of concept. Some other non-Arctic countries located on the flyways of Arctic-breeding waterbirds also annually monitor abundance and breeding success, and we advocate that future development of “Arctic waterbird indicators” should be as inclusive of data as possible to derive the most robust outputs and help account for effects of current changes in non-breeding waterbird distributions. The incorporation of non-Arctic datasets into assessments of the status of Arctic biodiversity is recognised as highly desirable, because logistic constraints in monitoring within the Arctic region limit effective population-scale monitoring there, in effect enabling “monitoring at a distance”.
Despite constituting around 16% of the world’s population, we know little about the extent to which political parties encourage people with disabilities to participate in political parties. This article aims to fill that gap by providing a comparative analysis of political parties in Australia, Canada, New Zealand, and the United Kingdom. The research develops a framework for assessing the accessibility of political parties. The research finds evidence of activity in a small number of parties but finds relatively little evidence to suggest that parties are prioritizing this issue, especially when compared with the participation of other social groups. The article argues that we need greater research into the relationship between disability and political parties, concluding with a future research agenda.
We present a theoretical framework for porous media gravity currents propagating over rigid curvilinear surfaces. By reducing the flow dynamics to low-dimensional models applicable on surfaces where curvature effects are negligible, we demonstrate that, for finite-volume releases, the flow behaviour in both two-dimensional and axisymmetric configurations is primarily governed by the ratio of the released viscous fluid volume to the characteristic volume of the curvilinear surface. Our theoretical predictions are validated using computational fluid dynamics simulations based on a sharp-interface model for macroscopic flow in porous media. In the context of carbon dioxide geological sequestration, our findings suggest that wavy cap rock geometries can enhance trapping capacity compared with traditional flat-surface assumptions, highlighting the importance of incorporating realistic topographic features into subsurface flow models.
For an ideal I in a Noetherian ring R, the Fitting ideals $\mathrm{Fitt}_j(I)$ are studied. We discuss the question of when $\mathrm{Fitt}_j(I)=I$ or $\sqrt{\mathrm{Fitt}_j(I)}=\sqrt{I}$ for some j. A classical case is the Hilbert–Burch theorem when $j=1$ and I is a perfect ideal of grade 2 in a local ring.
A model is proposed for the one-dimensional spectrum and streamwise Reynolds stress in pipe flow for arbitrarily large Reynolds numbers. Constructed in wavenumber space, the model comprises four principal contributions to the spectrum: streaks, large-scale motions, very-large-scale motions and incoherent turbulence. It accounts for the broad and overlapping spectral content of these contributions from different eddy types. The model reproduces well the broad structure of the premultiplied one-dimensional spectrum of the streamwise velocity, although the bimodal shape that has been observed at certain wall-normal locations, and the $-5/3$ slope of the inertial subrange, are not captured effectively because of the simplifications made within the model. Regardless, the Reynolds stress distribution is well reproduced, even within the near-wall region, including key features of wall-bounded flows such as the Reynolds number dependence of the inner peak, the formation of a logarithmic region, and the formation of an outer peak. These findings suggest that many of these features arise from the overlap of energy content produced by both inner- and outer-scaled eddy structures combined with the viscous-scaled influence of the wall. The model is also used to compare with canonical turbulent boundary layer and channel flows, and despite some differences being apparent, we speculate that with only minor modifications to its coefficients, the model can be adapted to these flows as well.
This paper explores the transformative potential of artificial intelligence (AI), particularly generative AI (GenAI), in supporting the teaching, learning, and assessment of second language (L2) listening and speaking. It examines how AI technologies, such as spoken dialogue systems and intelligent personal assistants, can refine existing practices, offer innovative solutions, and address challenges related to spoken language competencies, as well as drawbacks they present. It highlights the role of GenAI, explores its capabilities and limitations, and offers insights into the evolving role of GenAI in language education. This paper discusses actionable insights for educators and researchers, outlining practical considerations and future research directions for optimizing GenAI integration in the learning and assessment of listening and speaking.
The present study relied on internet memes as a tool to possibly fight ageism and shape public views in a positive manner. Data collection took place between May and June 2024, recruiting 160 Israeli Arabs, aged 13 to 16, from 3 different schools. In total, 105 memes addressed ageism towards older people. Visual and written contents were described, followed by more interpretative analysis. The memes were classified into two main themes. The first concerned negative ageist stereotypes of older persons (n = 66). The second theme concerned attempts to combat ageism (n = 39). Even though students received explicit instructions to fight ageism via their meme production, most students produced memes which depicted older age and ageing in a negative stereotypical light. The study highlights the relatively high levels of ageism in this group of participants and points to areas needing further attention in future interventions to alleviate ageism. The present findings are important as they question the current thinking of the Arab population as characterized by familistic values of high levels of respect towards older persons.
Phoretic particles are often used as a simple model for experimental and theoretical studies of active matter. We develop a computational framework to resolve hydrodynamic and chemical interactions of multiple self-propelling phoretic particles suspended in two-dimensional Stokes flow. The proposed method is precise enough to resolve correctly the subtle transitions between different modes of spontaneous locomotion for a single particle, and fast and versatile enough to study multiparticle dynamics in periodic or confined domains. The particles are modelled as chemically active rigid circles, which can emit or absorb a solute into surrounding fluid. The interaction between particles and solute induces a slip flow on particle surfaces, and the solute is advected by the fluid flow and diffuses with a constant diffusivity. A fast boundary integral method is proposed to solve fluid–structure interaction in Stokes flow. Acceleration of this method is provided by splitting the velocity field due to a set of point forces into a short-range part with singularity and a long-range part which is sufficiently smooth, thanks to an Ewald-like decomposition. An overlapping mesh method is employed for advection–diffusion of the solute with moving boundaries. The idea is to decompose the computational domain into several overlapping subdomains, and body-fitted meshes are used to ensure sharp resolution of boundary conditions. The framework is validated separately for the Stokes problem and the advection–diffusion problem, reaching relatively high order of accuracy. We apply our framework to several practical problems, such as a single particle in a channel and particle suspensions, showing rich sets of behaviours.
Comprising the largest group of health care professionals, nurses play a great role and assume many responsibilities during disaster periods, when the public needs health care services the most. The aim of this study was to reveal the experiences of nurses assigned to the disaster area during relief efforts after the February 6, 2023 earthquakes in Türkiye.
Methods
This qualitative and descriptive study used the maximum variation sampling method, one of the purposive sampling methods, and was completed with 20 nurses. Data were analyzed using inductive content analysis.
Results
Four main themes emerged from the experiences of the nurses who provided health care services in the disaster area: experiences related to pre-mission processes, experiences during the mission, post-mission experiences, and recommendations for disaster preparedness.
Conclusions
Nurses’ experiences and suggestions revealed in this study may inform future disaster preparedness and disaster management plans, and this study’s results point to the need for the development of professional nursing skills in disaster management.
Following the French example, the Meloni government has introduced the phrase ‘sovranità alimentare’ (sovereignty in food) into the title of the ministry of agriculture, and makes clear that it is engaging in a very determined effort to defend and promote the cultural heritage of Italian cuisine on all fronts, at home and abroad. But the origins of this impulse go back to the 1980s and the arrival of the McDonald’s hamburger chain, which gave birth to the Slow Food movement, now a global phenomenon. All this conceals several paradoxes: Italian cuisine has always been open to hybridised versions invented elsewhere (especially in America); production in key sectors, including wine, depends on large numbers of immigrant workers at a time when the government is trying to discourage immigration; and the ‘sovereignty in food’ concept unwittingly unites the government and some of its most radical opponents. But the very basis of this concept is challenged by the hyper-protectionist trade policy of the Trump administration.
This article examines the Philippines’ engagement with international law and institutions under Duterte’s populist presidency. While populism is often associated with hostility toward multilateralism, this case study reveals a more nuanced dynamic. The article argues that state engagement under populist administrations is more complex than assumed, and populist rhetoric does not uniformly dictate international behaviour. Using a novel conceptual framework and empirical data, it analyzes the Philippines’ multilateral interactions in human rights, trade, and health. Duterte’s government displayed ritualistic engagement with the United Nations Human Rights Council (UNHRC), constructive engagement with the World Trade Organization (WTO) and World Health Organization (WHO), and destructive disengagement from the International Criminal Court (ICC). Key themes include the divergence between rhetoric and action, instrumental use of institutions for domestic priorities, and the critical filtering role of domestic institutions. These findings offer broader insights as to how populist states balance domestic imperatives with international commitments, offering broader insights into the interplay between populism, foreign policy, and multilateralism.
In this study, we demonstrate, for the first time, the existence of a short-wave instability in a Lamb–Oseen vortex subjected to a triangular strain field generated by three satellite vortices, which we term the triangular instability. We identify this instability by numerically integrating the linearised Navier–Stokes equations around a quasi-steady base flow to capture the most unstable mode and validate it by comparing results with theoretical predictions. We evaluate this instability by calculating the growth rates associated with the parametric resonant coupling of two Kelvin waves with the triangular strain field in the limit of small strain rate and large Reynolds number. Our analysis reveals that resonance occurs only for combinations of the azimuthal wavenumbers $m = 1$ and $m = - 2$ (or their symmetric counterparts with opposite signs). We observe several unstable modes with positive growth rates for a moderate viscous Reynolds number $10^4$ and straining parameter value $\epsilon = 0.008$, defined as the cube of the ratio of the core size to the distance from the satellite vortices. The most unstable mode, dominant at typically high Reynolds numbers, has $k \approx 5.18/a$ and $\omega \approx - 0.312\Omega$ (where $a$ and $\Omega$ denote the core size and central angular velocity). It exhibits negligible critical layer damping and remains the most unstable mode over a wide range of ${Re}$ and $\epsilon$. At lower Reynolds numbers, another mode with $k \approx 1.76/a$ and $\omega \approx - 0.407\Omega$, despite significant critical layer damping, becomes the most unstable.
This study provides a comprehensive analysis of the impact of helideck surface conditions on the safe operation of helicopter landing and take-off platforms on offshore drilling vessels. Over time, the deterioration of helideck surface coatings necessitates periodic friction coefficient testing every two years in compliance with international standards. Surface coatings that fail to meet the required thresholds are replaced, and the performance of the renewed surface is reassessed using the Helideck Micro GripTester (HMGT), in accordance with U.K. Safety Regulation Group CAP 437 (2023) standards for offshore helicopter landing areas. The findings indicate that the renewed helideck surface coatings lead to a significant increase in the coefficient of friction, thereby enhancing the stability of helicopters upon landing and while on deck. Independent sample t-test and correlation analyses confirmed statistically significant differences between the old and new surface conditions, demonstrating the positive impact of surface improvements on coefficient of friction and, therefore, operational safety. Furthermore, machine learning techniques were employed to model and analyse the non-linear relationships between surface conditions and flow number. The model results demonstrate that variations in helideck surface coatings directly influence helicopter performance and operational safety. These findings underscore the critical importance of regular resurfacing and friction testing in ensuring the safety and reliability of offshore helicopter operations.
We present a versatile framework that employs Physics-Informed Neural Networks (PINNs) to discover the entropic contribution that leads to the constitutive equation for the extra-stress in rheological models of dilute polymer solutions. In this framework the training of the neural network is guided by an evolution equation for the conformation tensor, which is GENERIC-compliant. We compare two training methodologies for the data-driven PINN constitutive models: one trained on data from the analytical solution of the Oldroyd-B (OB) model under steady-state rheometric flows (PINN-rheometric), and another trained on in silico data generated from computational fluid dynamics (CFD) simulations of complex flow around a cylinder that use the OB model (PINN-complex). The capacity of the PINN models to provide good predictions is evaluated by comparison with CFD simulations using the underlying OB model as a reference. Both models are capable of predicting flow behaviour in transient and complex conditions; however, the PINN-complex model, trained on a broader range of mixed-flow data, outperforms the PINN-rheometric model in complex flow scenarios. The geometry agnostic character of our methodology allows us to apply the learned PINN models to flows with topologies different from those used for training.
Dyckia ibiramensis is an endemic species from southern Brazil, known for its ability to adapt to extreme environmental variations. This study reports the development of species-specific microsatellite markers and the assembly and annotation of the plastid genome of D. ibiramensis, aiming to generate new genomic resources useful for studies on the conservation and evolution of this endangered species. A total of 33,112 microsatellite loci were identified, of which 10 were selected and validated for genotyping 30 individuals from natural populations, showing high genetic variability. These 10 microsatellite markers were very informative for the evaluation of genetic variability. These microsatellite markers evidenced moderate to high genetic diversity at the individual level, low population differentiation, and the capacity of the species to recover population size from ancient genetic bottlenecks. The assembled plastid genome revealed conserved structures and the occurrence of features at the gene level, likely related to stress response to environmental conditions. This study expands the understanding of the genetics of D. ibiramensis, highlighting the importance of genomic strategies for the conservation of endangered species. In situ and ex situ conservation strategies should be used to avoid the extinction of this endemic southern Brazilian genetic resource in nature.
This study examines how university curriculum reforms that increase course selection flexibility influence entrepreneurial outcomes. Departing from traditional emphasis on educational attainment, we explore how institutional changes in education shape entrepreneurial tendencies among alumni. Leveraging a reform that removed constraints on course selection at a major university, we find that increased educational choice significantly fosters entrepreneurship. Our analysis reveals partial support for the moderating effects of individual, family, and spatial factors: the positive impact of these reforms is contingent on the type of electives and courses taken, with stronger effects observed among alumni with entrepreneurial parents, those born in urban areas, and those from higher socioeconomic backgrounds. These groups leverage specific course patterns to align their educational choices with entrepreneurial aspirations, enhancing their likelihood of pursuing entrepreneurial ventures. However, these findings also underscore the potential for educational reforms to exacerbate inequalities, disproportionately benefiting those with preexisting advantages. By integrating insights on institutional changes, course-taking patterns, and individual moderators, this study advances understanding of the interplay between education and entrepreneurship, offering implications for designing more equitable educational policies.