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Exploring the gluon propagator in a generalized gauge condition
No full textGauge theories, fundamental to modern physics, shape our understanding of particles, atomic nuclei, and the universe’s evolution. Central to these theories is the invariance of the Lagrangian density under specific transformations. This study addresses the quantization of non-abelian gauge theory using the established path integral formalism. We introduce a novel, generalized gauge condition VμGaμ=0 as Vμ=ζ∂μ+σnμ; here, Gaμ represents the gluon field, nμ is an arbitrary constant four-vector, and ζ and σ are real constant parameters. This novel gauge condition facilitates derivations of gluon propagators, which are crucial for understanding the strong force. Our findings demonstrate that this generalized gauge condition seamlessly bridges covariant and non-covariant gauges, as the results reduce to known expressions when ζ = 1, σ = 0 (covariant gauge) and ζ = 0, σ = 1 (non-covariant gauge). Our results recover the known expressions for gluon propagators. This new gauge condition offers a powerful tool for deriving explicit propagator expressions, bridging the gap between covariant and non-covariant gauges. Our findings not only contribute to a deeper understanding of Yang–Mills theories but also shed light on how to address inherent ambiguities within quantum field theories. © Indian Association for the Cultivation of Science 2024
Collapse fragility models for unreinforced masonry buildings under flood and flow-type landslide actions
No full textPressure-induced amorphization of ZIF-8: Deciphering the role of atomic charge assignments and adsorbed CH4 molecules through atomistic insights
No full textRevealing the gas adsorption properties of amorphous metal organic frameworks (aMOFs) remains both vexed and vital as novel adsorbents demand an accurate computational description of disordered MOFs. This work aims to examine the effect of atomic charge assignment methods and the presence of confined gas molecules on the pressure-induced amorphization process of crystalline zeolitic imidazolate framework-8 (cryZIF-8). We performed molecular dynamics (MD) simulations using a flexible and transferable force field, ZIF-FF, with four charge models, namely, Qeq, PACMAN, PACMOF, and DDEC. Our results show that the crystalline-amorphous transition (intermediate phase) and the onset pressures for amorphization and crystallization exhibit minimal dependence on the assigned atomic charges. The crystallinity of ZIF-8 is preserved up to 0.8 GPa, but further pressure increases result in the loss of pair distribution function (PDF) peaks from similar to 7 to similar to 30 & Aring;, indicating the degradation of long-range order and the transition to an amorphous state. Incorporating a moderate number of adsorbed CH4 molecules (<= 54) into cryZIF-8 does not affect the initial amorphization pressure. However, when the number of adsorbed CH4 molecules increases to a saturated loading (400), the amorphization onset shifts to similar to 1.0 GPa. We also evaluated the CO2/CH4 separation performances of selected aZIF-8 structures at vacuum swing adsorption (VSA) and pressure swing adsorption (PSA) conditions using grand canonical Monte Carlo (GCMC) simulations. Several adsorbent performance evaluation metrics, including adsorption selectivity, working capacity, adsorbent performance score (APS), and regenerability, were computed at 298 K and compared between aZIF-8 and cryZIF-8. Our results show that aZIF-8 outperforms cryZIF-8 in terms of adsorption selectivity and APS, highlighting its potential for gas adsorption applications.TÜBİTA
Improving the 3D Printability of High-Volume Fly Ash Mixtures Through Addition of Mineral Admixtures
No full textOptimizing production and remanufacturing decisions for make-to-stock hybrid manufacturing systems using real-time information on products in use
No full textThis study presents an analytical framework for make-to-stock hybrid manufacturing systems that use both virgin and returned materials to produce a single product. The system is modelled as a Markov Decision Process, and a linear programming approach is used to determine optimal decisions on when to produce, which material to use, and whether to remanufacture or dispose of returned items. A key feature of the model is the inclusion of real-time tracking information on products in use within such a circular system, which supports informed and timely decision-making. We conduct a comparative numerical analysis between the optimal policy and a simplified one that omits orbit information. Our results show that excluding orbit information leads to an average profit loss of 2.21%, with losses reaching up to 11.18% in some settings, quantifying the economic impact of tracking capabilities in closed-loop systems. We also examine the effect of regulatory minimums that require a portion of production to use returned materials. While such policies support sustainability goals, they may reduce profitability when return rates are low or holding costs are high. We believe these findings offer practical guidance for firms seeking to balance profitability, regulatory compliance, and operational simplicity in circular manufacturing environments.European Union (EU
The rubber tool illusion reveals how body image modifies body schema
No full textRubber hand illusion and tool-use paradigms have been extensively used to investigate body representation. Although both approaches rely on multisensory integration and external object incorporation, they are typically studied in isolation. Here, we introduce a novel paradigm that combines these methods to investigate whether perceptual modifications to body representation can induce motor changes, and vice versa. First, participants completed a tool-use task, actively using a short or long grabber tool to move cubes. When asked to point toward the forearm midpoint, only long tool users exhibited a distal shift, denoting an expansion in motor representation. Next, participants experienced the "rubber tool illusion" by passively holding the same tool while observing a rubber hand grasp an identical-looking tool. Notably, participants holding a short tool exhibited an expanded forearm representation when they observed a synchronously stroked long tool during illusion. Control experiments revealed that this effect depended on prior active tool use, embodiment of the observed rubber hand/tool, and a length mismatch between the held and observed tools. These findings reveal for the first time that motor representation of forearm length, a component of body schema, can be modulated by changes in body image. Public Significance Statement Over the past 25 years, research on how the brain represents the body has identified (at least) two distinct systems: body image, which governs conscious perception, and body schema, which guides unconscious movement. While body schema is known to influence body image, evidence for the reverse has been limited. This study provides new evidence that changes in body image can, in fact, alter body schema. By combining two classical methods for studying the embodiment of external objects-tool use and the rubber hand illusion-we found that merely perceiving a longer tool as part of the body had a similar effect on unconscious motor responses as actively using it. These findings challenge traditional views by showing that conscious body perception can shape unconscious movement.TÜBİTAK ; Bogazici Universit
Optimization of drone base station locations and mobile charging drone routing for post-disaster communication
No full textIn the aftermath of a disaster, traditional communication systems often become inaccessible, creating significant challenges for rescue teams and affected individuals. This research aims to design an innovative communication system to bridge this gap, ensuring efficient information transfer and establishing reliable communication channels between rescue teams and affected people. The focus is on using drones as communication tools to address this challenge. The study explores the use of drones as data collection and transmission platforms in disaster-stricken areas. By collecting information from individuals, including text messages and location data from different platforms, drones can efficiently transmit vital data to the communication backhaul. An optimization model is formulated to decide on the 3D location of drone base stations while maximizing coverage and service quality. In addition, mobile power drones are also required to supply the power for deployed base stations and data transfer; the model also decides on the routing of multiple power drones. To solve the problem efficiently, a clustering-based matheuristic is developed to determine the locations of the base stations. We show the solution performance of the model and the effectiveness of our heuristic algorithm in a case study using data from Sultanbeyli province in T & uuml;rkiye. The heuristic algorithm solves all the case study instances, which consist of 700 nodes, 75-105 stationary drones, and 6-8 mobile drones, in less than an hour. The results show that with 105 stationary and 8 mobile drones, we can cover 82% of the users. Furthermore, we demonstrate how this coverage can be increased to 95% by implementing certain adjustments. The findings offer insights into the potential of using drone base stations in post-disaster scenarios, thereby empowering disaster management agencies with enhanced communication capabilities for improved coordination and response in the face of disaster.Publisher versio
Developing an intuitive decision support system for equitable vaccine distribution during pandemics
No full textEffective organization of the vaccine supply chain is vital to achieve high vaccination rates in pandemics. This paper presents a novel approach for developing a decision support system (DSS) to support health officials and policymakers who must make timely and impactful decisions with limited information for distributing vaccines. We combine a stakeholder-informed systems approach for problem definition with a user-centered design approach for DSS development. The methodology has been tested during the COVID-19 pandemic. We used system modeling to capture stakeholders' knowledge, experience, and learnings from the H1N1 pandemic, leading us to focus on the central vaccine allocation problem (CVAP), which involves determining the number of vaccines allocated to each municipality in an equitable way. We designed a dashboard that embedded a mathematical model as a DSS for in-country CVAP during a pandemic. A Lightning Decision Jam workshop was conducted to define the DSS's characteristics, with the visualization of scenarios and decision-making transparency being key features during the development process. We validated the DSS with policymakers and built it for the Norwegian context, with flexibility for adaptation to other regions, particularly those still grappling with high vaccine supply deficits. Our approach offers a novel and practical way to develop DSSs to support policymakers making critical decisions during pandemics.Research Council of Norway ; Norwegian Institute of Public HealthPublisher versio
Liberal norm contestation in the periphery: Assessing Türkiye's shifting peacemaking approach in Cyprus
No full textThe contestation of liberal peacemaking is assessed as part of a broader normative shift, characterized by growing challenges to the Liberal International Order (LIO), led by rising powers such as Russia and China. This paper focuses on Türkiye as a rising middle-power country situated on the European periphery to assess Türkiye’s evolving peacemaking approach regarding the Cyprus conflict. The political discourse for the post-2017 period reveals that Türkiye has engaged in two contestation types with regard to the Cyprus conflict: First, power contestation, through which Türkiye contests the actorness of the EU and the UN in peacemaking in Cyprus. Second, normative contestation, wherein Türkiye prioritizes sovereign equality over mediated negotiations and contests the selective application of core liberal principles such as justice and rights in peacemaking in Cyprus. Both contestation strategies reflect Türkiye’s effort to reassert agency and secure status as a rising power within the international order