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Finding personalized good-enough solutions to unsatisfiable stable roommates problems
Full text linkThe Stable Roommates problems are characterized by the preferences of agents over other agents as roommates. A solution is a partition of the agents into pairs that are acceptable to each other (i.e., they are in the preference lists of each other), and the matching is stable (i.e., there do not exist any two agents who prefer each other to their roommates and thus block the matching). Motivated by real-world applications, and considering that stable roommates problems do not always have solutions, we continue our studies to compute “good-enough” matchings. In addition to the agents’ habits and habitual preferences, we consider their networks of preferred friends and introduce a method to generate personalized solutions to stable roommates problems. We illustrate the usefulness of our method with examples and empirical evaluations
Foreign policy as domestic politics in populist competitive authoritarianism: the case of the May 2023 elections in Turkey
No full textIn populist competitive authoritarian regimes, the distinction between the domestic and the foreign has become increasingly more porous. Yet we have limited knowledge about how populist politicians in competitive authoritarian regimes use foreign policy to mobilise their electoral base and fragment the opposition to advance their electoral agendas. This article focuses on how foreign policy issues were instrumentalised by Turkey’s President Erdoğan and his ruling AKP in the run-up to the Turkish presidential and parliamentary elections in May 2023 and finds that foreign policy was subject to populist politicisation through the discursive metanarrative of status elevation and external sponsorship
Track II diplomacy meets action research: fostering collaborative foreign policy between Türkiye and the EU in North Africa
No full textThis article explores the integration of Participatory Action Research (PAR) into foreign policy design, positioning it as a transformative tool to operationalise Track II diplomacy and foster inclusive, stakeholder-driven approaches. Focusing on EU–Türkiye cooperation in North Africa–particularly in Morocco, Algeria, and Egypt–the study applies PAR methodologies such as search conferences and clinical interviews with triangulation of other methods such as expert surveys to identify stakeholder-driven policy priorities. These include educational mobility, public infrastructure, health, renewable energy, and food security. While designed to engage both Track I and Track II actors, the process revealed the challenges of limited official participation, especially from North African governments, due to civic space restrictions and political sensitivities. Nonetheless, the findings demonstrate that PAR can build trust, surface actionable cooperation models, and complement conventional diplomacy. By moving beyond traditional security-focused Track II initiatives, the article contributes to rethinking foreign policy as a collaborative and participatory process. Ultimately, PAR is presented as a replicable, action-oriented model that complements conventional diplomacy and contributes to ongoing debates on democratising international relations through more adaptive and inclusive practices
Solution approaches for a stochastic lot sizing problem with limited inventory
No full textIn this study, we focus on a lot sizing problem with stochastic production and setup times and with limited inventory. In this problem, a single capacitated machine is used to produce several different items in each time period. Due to realization of stochastic times, companies may need to use overtime leading to additional costs considered as a part of the total operational cost. We model this problem as a stochastic programming where overtime values correspond to recourse decisions. Two solution approaches are developed. A first type of approach is based on tabu search algorithm where we employ a local search method specifically focusing on inventory bounds. A second type of solution approach is based on solving a stochastic programming model with a set of sample scenarios. We provide extensive computational results and confirm that the proposed procedures are effective to obtain very good solutions to be performed in real-life settings
Optimization of PLGA nanoparticle formulation via microfluidic and batch nanoprecipitation techniques
Full text linkPolymeric nanoparticles based on poly(lactic-co-glycolic acid) (PLGA) are widely used in drug delivery, yet scalable and reproducible production methods remain a major challenge. In this study, we combine experimental nanoprecipitation and computational fluid dynamics (CFD) modeling to optimize PLGA nanoparticle formulation using both traditional batch and microfluidic methods. While Design of Experiments (DoE) was used to optimize the batch process, microfluidic mixing was systematically explored by varying flow parameters such as the flow rate ratio (FRR) and total flow rate (TFR). We compared two microfluidic mixer designs with Y-junction and three-inlet junction geometries to evaluate their impact on the mixing efficiency and nanoparticle formation. Experimental results revealed that the three-inlet design produced smaller, more uniform nanoparticles with superior post-lyophilization stability. CFD simulations confirmed these findings by displaying velocity fields and PLGA concentration gradients, demonstrating significantly more homogeneous mixing and efficient interfacial contact in the three-inlet configuration. Furthermore, simulated outlet concentrations were used to predict the nanoparticle size via theoretical modeling, which closely agreed with the experimental data. This integrated approach highlights the importance of microfluidic geometry in controlling nanoparticle nucleation dynamics and provides a framework for rational design of scalable nanomedicine production systems
Judicial transformation in a competitive authoritarian regime: evidence from the Turkish case
No full textWhat accounts for the variation in the judiciary's ability to serve as a democratic guardrail under populist rule? This article contends that populist governments use judicial activism against their political agenda to portray courts as institutions that curtail popular sovereignty and subsequently adopt a democratizing discourse to conceal their assault on the judiciary. Based on the Turkish case under the rule of the AKP (Justice and Development Party), it explores how the judiciary's democratic deficits provided a legitimation strategy for the ruling party's gradual capture of the courts. During its initial term, the right-wing populist AKP government faced staunch opposition from high courts aligned with the secular establishment. In response, it strategically used the Turkish Constitutional Court's counter-majoritarian decisions to legitimize its actions, paving the way for court-packing and other forms of judicial manipulation through a series of constitutional amendments. These changes set a dangerous precedent for future clashes with the judiciary, hastening the erosion of Turkish democracy and the subsequent shift toward a competitive authoritarian regime
Fabrication of binder-free Ni-Mn oxalate electrode for supercapacitor application
No full textHerein, we have prepared binder-free flexible Ni-Mn oxalate supercapacitor electrode by simple hydrothermal method. The nickel foam as substrate as well as source of Ni was employed to Ni-Mn oxalate nanostructure. The galvanostatic charge-discharge measurements at range of applied current densities exhibit efficient supercapacitor behavior with 86.3% capacity retention till 10,000 charge discharge cycles and 99% Coloumbic efficiency. The cyclic voltammetry curves at different scan rates reveal good rate capability and stability of Ni-Mn oxalate electrode. The electrochemical impedance study with lower resistance and Warburg element demonstrates higher conductivity and rapid electron/ions diffusion rate. Therefore, synergistic effects of binary Ni-Mn as metal oxalates has overall enhanced the electrochemical performance of Ni-Mn oxalate electrode for supercapacitor application
Exploring the discrete and continuous edge improvement problems: models and algorithms
No full textIn this paper, we investigate the edge improvement problem where the fixed edge traversal time assumption of the traditional network flow problems is relaxed. We consider two variants of the problem: one where improvement decisions are restricted to a discrete set (discrete edge improvement problem), and the other where they can take any value within a specified range (continuous edge improvement problem). We first analyze both problem variants on a tree-shaped network and discuss their computational complexities. For the general case, where the underlying network has no special structure, we provide mixed-integer programming (MIP) formulations for both versions of the problem. To the best of our knowledge, this study is the first to propose and compare different formulations for the discrete edge improvement problem and to present a formulation for the continuous edge improvement problem. Since the developed models do not perform well for medium and large problem instances, we introduce a Benders decomposition algorithm to solve the discrete edge improvement problem. Additionally, we employ it heuristically to find high-quality solution for the continuous edge improvement problem within reasonable times. We also devise an MIP formulation to find lower bounds for the continuous edge improvement problem, leveraging the McCormick envelopes and optimal solution properties. Our experiments demonstrate that the Benders decomposition algorithm outperforms the other formulations for the discrete edge improvement problem, while the heuristic method proposed for the continuous edge improvement problem provides quite well results even for large problem instances