498 research outputs found

    Classical Lie symmetries and reductions of a nonisospectral Lax pair

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    The classical Lie method is applied to a nonisospectral problem associated with a system of partial differential equations in 2+1 dimensions (Maccari A, J. Math. Phys. 39, (1998), 6547-6551). Identification of the classical Lie symmetries provides a set of reductions that give rise to different nontrivial spectral problems in 1+1 dimensions. The form in which the spectral parameter of the 1+1 Lax pair is introduced is carefully described.Comment: 11 pages (v2: A typo corrected in the authors' names

    Analysis of an unmitigated 2-inch cold leg LOCA transient with ASTEC and MELCOR codes

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    The analyses of postulated severe accident sequences play a key role for the international nuclear technical scientific community for the study of the effect of possible actions to prevent significant core degradation and mitigate source term release. To simulate the complexity of phenomena involved in a severe accident, computational tools, known as severe accident codes, have been developed in the last decades. In the framework of NUGENIA TA-2 ASCOM project, the analysis of an unmitigated 2-inch cold leg LOCA transient, occurring in a generic western three-loops PWR-900 MWe, has been carried out with the aim to give some insights on the modelling capabilities of these tools and to characterize the differences in the calculations results. The ASTEC V2.2b code (study carried out with ASTEC V2, IRSN all rights reserved, [2021]), and MELCOR 2.2 code have been used in this code-to-code benchmark exercise. In the postulated transient, the unavailability of all active injection coolant systems has been considered and only the injection of accumulators has been assumed as accident mitigation strategy

    A methodological approach to upscale toward an agroecology system in EU-LAFSs: The case of the parma bio-district

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    The increasing interest in bio-districts is part of the debate on the capacity to integrate agri-food systems and territory in order to improve the quality of life in rural communities. Considering the goals of developing and promoting an innovative territorial rural development approach, the bio-district can become a process toward a more sustainable model represented by the agroecological agriculture system. The paper presents a case study of the Parma bio-district through the approach of a Localized Agri Food System (LAFS) to verify whether bio-districts can be a tool for scaling up towards agroecology. Stakeholder classification and analysis are conducted using an influence-interest matrix. We identified four groups of stakeholders in relation to their interests and power to influence the process. In the case of the Parma bio-district the role of local institutions in dialogue with consumers and producers' associations is crucial for success. We conclude that bio-districts can be a tool for a scaling-up towards agroecology since they can facilitate a synergetic relation between organic and agroecological agriculture, spreading organic agriculture more widely around the local area. However, the involvement of a wide variety of different stakeholders means that governance is a key element in facilitating "cross fertilization" and preventing the process from becoming purely formulaic

    Ingress of Coolant Event simulation with TRACE code with accuracy evaluation and coupled DAKOTA Uncertainty Analysis

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    Among the Postulated Initiating Events in nuclear fusion plants, the Ingress of Coolant Event (ICE) in the Plasma Chamber is one of the main safety issues. In the present paper, the best estimate thermal-hydraulic system code TRACE, developed by USNRC, has been adopted to study the ICE, and it has been qualified based on experimental results obtained in the Integrated ICE facility at JAERI. A nodalization has been developed in the SNAP environment/architecture, using also the TRACE 3D Vessel component where multidimensional phenomena could occur. The accuracy of the code calculation has been assessed both from a qualitative and quantitative point of view. In addition, an Uncertainty Analysis (UA), with the probabilistic method to propagate the input uncertainties, has been performed to characterize the dispersion of the results. The analysis has been carried out with the DAKOTA toolkit coupled with TRACE code in the SNAP environment/architecture. Results show the adequacy of the 3D nodalization and the capability of the code to follow the transient evolution also at a very low pressure. Response correlations have been computed to characterize the correlation between the selected uncertain input parameters and the Plasma Chamber pressure

    A Methodological Approach to Upscale Toward an Agroecology System in EU-LAFSs: The Case of the Parma Bio-District

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    The increasing interest in bio-districts is part of the debate on the capacity to integrate agri-food systems and territory in order to improve the quality of life in rural communities. Considering the goals of developing and promoting an innovative territorial rural development approach, the bio-district can become a process toward a more sustainable model represented by the agroecological agriculture system. The paper presents a case study of the Parma bio-district through the approach of a Localized Agri Food System (LAFS) to verify whether bio-districts can be a tool for scaling up towards agroecology. Stakeholder classification and analysis are conducted using an influence–interest matrix. We identified four groups of stakeholders in relation to their interests and power to influence the process. In the case of the Parma bio-district the role of local institutions in dialogue with consumers and producers’ associations is crucial for success. We conclude that bio-districts can be a tool for a scaling-up towards agroecology since they can facilitate a synergetic relation between organic and agroecological agriculture, spreading organic agriculture more widely around the local area. However, the involvement of a wide variety of dierent stakeholders means that governance is a key element in facilitating “cross fertilization” and preventing the process from becoming purely formulaic

    Sustained low-efficiency dialysis with regional citrate anticoagulation in critically ill patients with COVID-19 associated AKI: A pilot study

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    Acute Kidney Injury (AKI) is a frequent complication in critically ill patients with Coronavirus disease 2019 (COVID-19), and it has been associated with worse clinical outcomes, especially when Kidney Replacement Therapy (KRT) is required. A condition of hypercoagulability has been frequently reported in COVID-19 patients, and this very fact may complicate KRT management. Sustained Low Efficiency Dialysis (SLED) is a hybrid dialysis modality increasingly used in critically ill patients since it allows to maintain acceptable hemodynamic stability and to overcome the increased clotting risk of the extracorporeal circuit, especially when Regional Citrate Anticoagulation (RCA) protocols are applied. Notably, given the mainly diffusive mechanism of solute transport, SLED is associated with lower stress on both hemofilter and blood cells as compared to convective KRT modalities. Finally, RCA, as compared with heparin-based protocols, does not further increase the already high hemorrhagic risk of patients with AKI. Based on these premises, we performed a pilot study on the clinical management of critically ill patients with COVID-19 associated AKI who underwent SLED with a simplified RCA protocol. Low circuit clotting rates were observed, as well as adequate KRT duration was achieved in most cases, without any relevant metabolic complication nor worsening of hemodynamic status

    In search for multi-target ligands as potential agents for diabetes mellitus and its complications—a structure-activity relationship study on inhibitors of aldose reductase and protein tyrosine phosphatase 1b

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    Diabetes mellitus (DM) is a complex disease which currently affects more than 460 million people and is one of the leading cause of death worldwide. Its development implies numerous metabolic dysfunctions and the onset of hyperglycaemia-induced chronic complications. Multiple ligands can be rationally designed for the treatment of multifactorial diseases, such as DM, with the precise aim of simultaneously controlling multiple pathogenic mechanisms related to the disease and providing a more effective and safer therapeutic treatment compared to combinations of selective drugs. Starting from our previous findings that highlighted the possibility to target both aldose reductase (AR) and protein tyrosine phosphatase 1B (PTP1B), two enzymes strictly implicated in the development of DM and its complications, we synthesised 3-(5-arylidene-4-oxothiazolidin-3-yl)propanoic acids and analogous 2-butenoic acid derivatives, with the aim of balancing the effectiveness of dual AR/PTP1B inhibitors which we had identified as designed multiple ligands (DMLs). Out of the tested compounds, 4f exhibited well-balanced AR/PTP1B inhibitory effects at low micromolar concentrations, along with interesting insulin-sensitizing activity in murine C2C12 cell cultures. The SARs here highlighted along with their rationalization by in silico docking experiments into both target enzymes provide further insights into this class of inhibitors for their development as potential DML antidiabetic candidates
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