2,643 research outputs found

    Food prosumption technologies : A symbiotic lens for a degrowth transition

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    Prosumption is gaining momentum among the critical accounts of sustainable consumption that have thus far enriched the marketing discourse. Attention to prosumption is increasing whilst the degrowth movement is emerging to tackle the contradictions inherent in growth-driven, technology-fueled, and capitalist modes of sustainable production and consumption. In response to dominant critical voices that portray technology as counter to degrowth living, we propose an alternative symbiotic lens with which to reconsider the relations between technology, prosumption, and degrowth living, and assess how a degrowth transition in the context of food can be carried out at the intersection of human–nature–technology. We contribute to the critical debates on prosumption in marketing by analyzing the potentials and limits of technology-enabled food prosumption for a degrowth transition through the degrowth principles of conviviality and appropriateness. Finally, we consider the sociopolitical challenges involved in mobilizing such technologies to achieve symbiosis and propose a future research agenda.©2023 Sage Publications. The article is protected by copyright and reuse is restricted to non-commercial and no derivative uses. Users may also download and save a local copy of an article accessed in an institutional repository for the user's personal reference.fi=vertaisarvioitu|en=peerReviewed

    AB-INITIO INVESTIGATION OF 2D MATERIALS FOR GAS SENSING, ENERGY STORAGE AND SPINTRONIC APPLICATIONS

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    The field of Two Dimensional (2D) materials has been extensively studied since their discovery in 2004, owing to their remarkable combination of properties. My thesis focuses on exploring novel 2D materials such as Graphene Nanoribbon (GNR), holey carbon nitride C2N, and MXenes for energy storage, gas sensing, and spintronic applications, utilizing state-of-the-art techniques that combine Density Functional Theory (DFT) and Non-Equilibrium Greens Functions (NEGF) formalism; namely Vienna Ab-initio Simulation Package (VASP) and Atomistic Toolkit (ATK) package.Firstly, on the side of gas sensing, the burning of fossil fuels raises the level of toxic gas and contributes to global warming, necessitating the development of highly sensitive gas sensors. To start with, the adsorption and gas-sensing properties of bilaterally edge doped (B/N) GNRs were investigated. The transport properties revealed that the bilateral B/N edge-doping of GNR yielded Negative Differential Resistance (NDR) IV-characteristics, due to the electron back-scattering which was beneficial for selective gas sensing applications. Therefore, both GNR: B/N were found to be good sensors for NO2 and SO3 respectively. After that, the catalytic activity of four magnetic transition metal “TM” elements (e.g., Mn, Fe, Co and Ni) embedded in C2N pores, as Single-Atom Catalysts (SAC), was tested towards detecting toxic oxidizing gases. The results of spin-polarized transport properties revealed that Ni- and Fe-embedded C2N are the most efficient in detecting NO/ NO2 and NO2 molecules.Secondly, on the side of energy storage, since the fossil fuels reserves are depleting at an alarming rate, there is an urgent need for alternative forms of energy to meet the ever-growing demand for energy. Hydrogen is a popular form of clean energy. However, its storage and handling are challenging because of its explosive nature. The effect of magnetic moment on the hydrogen adsorption and gas-sensing properties in Mn-embedded in C2N were investigated. Two distinct configurations of embedment were considered: (i) SAC: 1Mn@C2N; and (ii) DAC: Mn2@C2N. Based on the huge changes in electronic and magnetic properties and the low recovery time (i.e., τ ≪ 1 s, τ = 92 μs and 1.8 ms, respectively), we concluded that C2N:Mn is an excellent candidate for (reusable) hydrogen magnetic gas sensor with high sensitivity and selectivity and rapid recovery time. Then, a comparative study of hydrogen storage capabilities on Metal- catalyst embedded (Ca versus Mn) C2N is presented which demonstrated the stability of these metal structures embedded on the C2N substrate. We proposed Ca@C2N and Mn@C2N for dual applications- hydrogen storage and a novel electrode for prospective metal-ion battery applications owing to its high irreversible uptake capacity 200 mAhg-1.Thirdly, on the side of data storage, spintronics is an emerging field for the next generation nanoelectronics devices to reduce their power consumption and to increase their memory and processing capabilities. Designing 2D-materials that exhibit half-metallic properties is important in spintronic devices that are used in low-power high-density logic circuits. We tested samples comprising of SAC and DAC of Mn embedded in a C2N sample size 2×2 primitive cells as well as their combinations in neighboring large pores. Many other TM catalysts were screened, and the results show the existence of half metallicity in just five cases: (a) C2N:Mn (DAC, SAC-SAC, and SAC-DAC); (b) C2N:Fe (DAC); and (c) C2N:Ni (SAC-DAC). Our results further showed the origins of half-metallicity to be attributed to both FMC and synergetic interactions between the catalysts with the six mirror images, formed by the periodic-boundary conditions.Lastly, on the side of batteries, sodium-sulfur batteries show great potential for storing large amounts of energy due to their ability to undergo a double electron- redox process, as well as the plentiful abundance of sodium and sulfur resources. However, the shuttle effect caused by intermediate sodium polysulfides (Na2Sn) limits their performance and lifespan. To address this issue, we proposed two functionalized MXenes Hf3C2T2 and Zr3C2T2 (T= F, O), as cathode additives to suppress the shuttle effect. We found that both Hf3C2T2 and Zr3C2T2 systems inhibit the shuttle effect by binding to Na2Sn with a binding energy higher than the electrolyte solvents. The decomposition barrier for Na2Sn on the O functionalized MXenes gets reduced which enhances the electrochemical process. Overall, our findings show that the tuning of 2D materials can lead to promising applications in various fields, including energy storage, gas sensing, and spintronics

    Coexistence of multiuser entanglement distribution and classical light in optical fiber network with a semiconductor chip

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    Building communication links among multiple users in a scalable and robust way is a key objective in achieving large-scale quantum networks. In realistic scenario, noise from the coexisting classical light is inevitable and can ultimately disrupt the entanglement. The previous significant fully connected multiuser entanglement distribution experiments are conducted using dark fiber links and there is no explicit relation between the entanglement degradations induced by classical noise and its error rate. Here we fabricate a semiconductor chip with a high figure-of-merit modal overlap to directly generate broadband polarization entanglement. Our monolithic source maintains polarization entanglement fidelity above 96% for 42 nm bandwidth with a brightness of 1.2*10^7 Hz/mW. We perform a continuously working quantum entanglement distribution among three users coexisting with classical light. Under finite-key analysis, we establish secure keys and enable images encryption as well as quantum secret sharing between users. Our work paves the way for practical multiparty quantum communication with integrated photonic architecture compatible with real-world fiber optical communication network

    Quantum simulator of link models using spinor dipolar ultracold atoms

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    We propose a scheme for the quantum simulation of quantum link models in two-dimensional lattices. Our approach considers spinor dipolar gases on a suitably shaped lattice, where the dynamics of particles in the different hyperfine levels of the gas takes place in one-dimensional chains coupled by the dipolar interactions. We show that at least four levels are needed. The present scheme does not require any particular fine-tuning of the parameters. We perform the derivation of the parameters of the quantum link models by means of two different approaches, a non-perturbative one tied to angular momentum conservation, and a perturbative one. A comparison with other schemes for (2+1)(2+1)-dimensional quantum link models present in literature is discussed. Finally, the extension to three-dimensional lattices is presented, and its subtleties are pointed out.Comment: 21 pages, 12 figure

    Digital agriculture: research, development and innovation in production chains.

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    Digital transformation in the field towards sustainable and smart agriculture. Digital agriculture: definitions and technologies. Agroenvironmental modeling and the digital transformation of agriculture. Geotechnologies in digital agriculture. Scientific computing in agriculture. Computer vision applied to agriculture. Technologies developed in precision agriculture. Information engineering: contributions to digital agriculture. DIPN: a dictionary of the internal proteins nanoenvironments and their potential for transformation into agricultural assets. Applications of bioinformatics in agriculture. Genomics applied to climate change: biotechnology for digital agriculture. Innovation ecosystem in agriculture: Embrapa?s evolution and contributions. The law related to the digitization of agriculture. Innovating communication in the age of digital agriculture. Driving forces for Brazilian agriculture in the next decade: implications for digital agriculture. Challenges, trends and opportunities in digital agriculture in Brazil

    A new framework for using weather‐sensitive surplus power reserves in critical infrastructure

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    Reserve power systems are widely used to provide power to critical infrastructure systems in the event of power outages. The reserve power system may be subject to regulation, typically focussing on a strict operational time commitment, but the energy involved in supplying reserve power may be highly variable. For example, if heating or cooling is involved, energy consumption may be strongly influenced by prevailing weather conditions and seasonality. Replacing legacy assets (often diesel generators) with modern technologies could offer potential benefits and services back to the wider electricity system when not in use, therefore supporting a transition to low-carbon energy networks. Drawing on the Great Britain telecommunications systems as an example, this paper demonstrates that meteorological reanalyses can be used to evaluate capacity requirements to maintain the regulated target of 5-days operational reserve. Across three case-study regions with diverse weather sensitivities, infrastructure with cooling-driven electricity demand is shown to increase energy consumption during summer, thus determining the overall capacity of the reserve required and the availability of ‘surplus’ capacity. Lower risk tolerance is shown to lead to a substantial cost increase in terms of capacity required but also enhanced opportunities for surplus capacity. The use of meteorological forecast information is shown to facilitate increased surplus capacity. Availability of surplus capacity is compared to a measure of supply–stress (demand-net-wind) on the wider energy network. For infrastructure with cooling-driven demand (typical of most UK telecommunication assets), it is shown that surplus availability peaks during periods of supply–stress, offering the greatest potential benefit to the national electricity grid

    Algebraic Structure of Topological and Conformal Field Theories

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    Quantum field theories (QFTs) are geometric and analytic in nature. With enough symmetry, some QFTs may admit partial or fully algebraic descriptions. Topological and conformal field theories are prime examples of such QFTs. In this thesis, the algebraic structure of 2+1D Topological Quantum Field Theories (TQFTs) and associated Conformal Field Theories (CFTs) is studied. The line operators of 2 + 1D TQFTs and their correlation functions are captured by an algebraic structure called a Modular Tensor Category (MTC). A basic property of line operators is their operator product expansion. This is captured by the fusion rules of the MTC. We study the existence and consequences of special fusion rules where two line operators fuse to give a unique outcome. There is a natural action of a Galois group on MTCs which allows us to jump between points in the space of TQFTs. We study how the physical properties of a TQFT like its symmetries and gapped boundaries transform under Galois action. We also study how Galois action interacts with other algebraic operations on the space of TQFTs like gauging and anyon condensation. Moreover, we show that TQFTs which are invariant under Galois action are very special. Such Galois invariant TQFTs can be constructed from gauging symmetries of certain simple abelian TQFTs. TQFTs also admit gapless boundaries. In particular, 1+1D Rational CFTs (RCFTs) and 2+1D TQFTs are closely related. Given a chiral algebra, the consistent partition functions of an RCFT are classified by surface operators in the bulk 2 + 1D TQFT. On the other hand, Narain RCFTs can be constructed from quantum error-correcting codes (QECCs). We give a general map from Narain RCFTs to QECCs. We explore the role of topological line operators of the RCFT in this construction and use this map to give a quantum code theoretic interpretation of orbifolding
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