2,787 research outputs found

    Persistent current formation in a high-temperature Bose-Einstein condensate: an experimental test for c-field theory

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    Experimental stirring of a toroidally trapped Bose-Einstein condensate at high temperature generates a disordered array of quantum vortices that decays via thermal dissipation to form a macroscopic persistent current [T. W. Neely em et al. arXiv:1204.1102 (2012)]. We perform 3D numerical simulations of the experimental sequence within the Stochastic Projected Gross-Pitaevskii equation using ab initio determined reservoir parameters. We find that both damping and noise are essential for describing the dynamics of the high-temperature Bose field. The theory gives a quantitative account of the formation of a persistent current, with no fitted parameters.Comment: v2: 7 pages, 3 figures, new experimental data and numerical simulation

    Equivalent Electric and Heat-Pump Water Heater Models for Aggregated Community-Level Demand Response Virtual Power Plant Controls

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    Advanced control techniques may be used to establish a virtual power plant to regulate the operation of electric water heaters, which may be regarded as a “uni-directional battery” and a major component of a hybrid residential energy storage system. In order to estimate the potential of regulating water heaters at the aggregated level, factors including user behavior, number of water heaters, and types of water heaters must be considered. This study develops generic water heater load curves based on the data retrieved from large experimental projects for resistive electric water heaters (EWHs) and heat pump water heaters (HPWHs). A community-level digital twin with scalability has been developed to capture the aggregated hot water flow and average hot temperature in the tank. The results in this paper also include the “energy take” in line with the CTA-2045 standard and Energy Star specification. The data from the experiments demonstrated that changing from an EWH to an HPWH reduces electricity usage by approximately 70%. The case study showed that daily electricity usage could be shifted by approximately 14% and 17% by EWH and HPWHs, respectively, compared to their corresponding average power. Another case study showed that both EHWs and HPWHs, coordinated with PV to reduce morning and evening peaks, could shift approximately 22% of the daily electricity

    Aggregated Generic Load Curve for Residential Electric Water Heaters

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    Advanced control techniques may be used to regulate the operation of residential appliances to establish a virtual power plant. The electric water heater may be regarded as a “uni-directional battery” and a major component of a hybrid residential energy storage system. One of the main constraints of implementing demand response with EWH relates to the unpredictable customer behavior, which influences the domestic water tank temperature as well as the EWH operation cycle. This study analyzes the operation of multiple water heaters and develops an aggregated generic water heater load curve for the average residential customer based on experimental data retrieved from the A.O. Smith Corporation. An equivalent thermal model capable of capturing the typical customer behavior and estimating the per unit hot water usage was developed. The proposed aggregated generic EWH load curve was validated through an example demand response program, in which the morning peak demand is shed in order to store the surplus PV power at midday in the EWH. Based on the representative hot water draw profile and the electric power profile, the change in average tank temperature was estimated and maintained within the customer acceptable range

    An ethical matrix for the reintroduction of trafficked primates:a platyrrhine case study

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    The illegal primate trade is one of the major drivers of the decline of nonhuman primate populations and a threat to their wellbeing. Thousands of trafficked primates enter rescue centers every year, and their destiny (release back into the wild, long-term captivity, or euthanasia) involves controversial decisions and complex ethical considerations. To navigate these issues, we developed an ethical matrix, an ethical framework previously used to address conservation-related issues. We gathered information from studies on the reintroduction of trafficked platyrrhines in Latin America from 1990 to 2022 to develop the matrix. We found 22 studies performed in eight Latin American countries, which included howler monkeys, spider monkeys, woolly monkeys, capuchin monkeys, squirrel monkeys, marmosets, and tamarins. We found that the reintroduction of trafficked platyrrhines may yield positive results for the welfare of individuals and for the conservation of their taxa and some of the potential negative effects, such as spillover of infectious agents to free-ranging populations or to human populations, or competition for resources between reintroduced monkeys and resident conspecifics have not yet been documented in the scientific literature, although this does not mean that they do not occur. We conclude that the ethical matrix is a useful method to consider the interests of all potential stakeholders and that the reintroduction of trafficked primates may be a viable management option if the individual welfare of the animals is considered, programs comply with the IUCN and government guidelines, and the objective and justification of the reintroduction are clear

    Runoff and discharge pathways of microplastics into freshwater ecosystems: A systematic review and meta-analysis

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    Although many studies have focused on the importance of littering and (or) illegal dumping as a source of plastic pollution to freshwater, other relevant pathways should be considered, including wastewater, stormwater runoff, industrial effluent/runoff, and agricultural runoff. Here, we conducted a meta-analysis focused on these four pathways. We quantified the number of studies, amount and characteristics of microplastics reported, and the methods used to sample and measure microplastics from each pathway. Overall, we found 121 studies relevant to our criteria, published from 2014 to 2020. Of these, 54 (45%) quantified and characterized microplastics in discharge pathways. Although most focused on wastewater treatment plant effluent (85%), microplastic concentrations were highest in stormwater runoff (0.009 to 3862 particles/L). Morphologies of particles varied among pathways and sampling methods. For example, stormwater runoff was the only pathway with rubbery particles. When assessing methods, our analysis suggested that water filtered through a finer (\u3c200 um) mesh and of a smaller volume (e.g., 6 L) captured more particles, and with a slightly greater morphological diversity. Overall, our meta-analysis suggested that all four pathways bring microplastics into freshwater ecosystems, and further research is necessary to inform the best methods for monitoring and to better understand hydrologic patterns that can inform local mitigation

    Characteristics of Two-Dimensional Quantum Turbulence in a Compressible Superfluid

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    Under suitable forcing a fluid exhibits turbulence, with characteristics strongly affected by the fluid's confining geometry. Here we study two-dimensional quantum turbulence in a highly oblate Bose-Einstein condensate in an annular trap. As a compressible quantum fluid, this system affords a rich phenomenology, allowing coupling between vortex and acoustic energy. Small-scale stirring generates an experimentally observed disordered vortex distribution that evolves into large-scale flow in the form of a persistent current. Numerical simulation of the experiment reveals additional characteristics of two-dimensional quantum turbulence: spontaneous clustering of same-circulation vortices, and an incompressible energy spectrum with k5/3k^{-5/3} dependence for low wavenumbers kk and k3k^{-3} dependence for high kk.Comment: 7 pages, 7 figures. Reference [29] updated for v

    Dissecting Clot Retraction and Platelet Aggregation: CLOT RETRACTION DOES NOT REQUIRE AN INTACT FIBRINOGEN CHAIN C TERMINUS

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    Fibrinogen mediates the processes of platelet aggregation and clot retraction. Previous studies have demonstrated that fibrinogen binding to the platelet receptor alphaIIbbeta3 requires the C-terminal residues of the fibrinogen gamma chain. We made a recombinant human fibrinogen that lacks the gamma chain C-terminal four residues (AGDV). As expected this fibrinogen did not support platelet aggregation. Unexpectedly, this variant did support clot retraction that was indistinguishable from retraction with normal recombinant or plasma fibrinogen. These results suggest that the site on fibrinogen that is required for platelet aggregation differs from the site on fibrin that is required for clot retraction

    Eudaimonistic Argumentation

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    Virtue theories have lately enjoyed a modest vogue in the study of argumentation, echoing the success of more far-reaching programmes in ethics and epistemology. Virtue theories of argumentation (VTA) comprise several conceptually distinct projects, including the provision of normative foundations for argument evaluation and a renewed focus on the character of good arguers. Perhaps the boldest of these is the pursuit of the fully satisfying argument, the argument that contributes to human flourishing. This project has an independently developed epistemic analogue: eudaimonistic virtue epistemology. Both projects stress the importance of widening the range of cognitive goals beyond, respectively, cogency and knowledge; both projects emphasize social factors, the right sort of community being indispensable for the cultivation of the intellectual virtues necessary to each project. This paper proposes a unification of the two projects by arguing that the intellectual good life sought by eudaimonistic virtue epistemologists is best realized through the articulation of an account of argumentation that contributes to human flourishing
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