An Evolutionary Approach for Learning Opponent's Deadline and Reserve Points in Multi-Issue Negotiation

The efficiency of automated multi-issue negotiation depends on the available information about the opponent. In a competitive negotiation environment, agents do not reveal their parameters to their opponents in order to avoid exploitation. Several researchers have argued that an agent's optimal strategy can be determined using the opponent's deadline and reserve points. In this paper, we propose a new learning agent, so-called Evolutionary Learning Agent (ELA), able to estimate its opponent's deadline and reserve points in bilateral multi-issue negotiation based on opponent's counter-offers (without any additional extra information). ELA reduces the learning problem to a system of non-linear equations and uses an evolutionary algorithm based on the elitism aspect to solve it. Experimental study shows that our learning agent outperforms others agents by improving its outcome in term of average and joint utility

Magnetic exchange interactions in Mn doped ZnSnAs₂ chalcopyrite

Accurate ab initio full-potential augmented plane wave (FP-LAPW) electronic calculations within generalized gradient approximation have been performed for Mn doped ZnSnAs₂ chalcopyrites, focusing on their electronic and magnetic properties as a function of the geometry related to low Mn-impurity concentration and the spin magnetic alignment (i.e., ferromagnetic vs antiferromagnetic). As expected, Mn is found to be a source of holes and localized magnetic moments of about 4 µB per Mn atom are calculated which are sufficiently large. The defect calculations are firstly performed by replacing a single cation (namely Zn and Sn) with a single Mn atom in the pure chalcopyrite ZnSnAs₂ supercell, and their corresponding formation energies show that the substitution of a Sn atom (rather than Zn) by Mn is strongly favored. Thereafter, a comparison of total energy differences between ferromagnetic (FM) and antiferromagnetic (AFM) are given. Surprisingly, the exchange interaction between a Mn pairs is found to oscillate with the distance between them. Consequently, the AFM alignment is energetically favored in Mn-doped ZnSnAs₂ compounds, except for low impurity concentration associated with lower distances between neighboring Mn impurities, in this case the stabilization of FM increases. Moreover, the ferromagnetic alignment in the Mn-doped ZnSnAs₂ systems behaves half-metallic; the valence band for majority spin orientation is partially filled while there is a gap in the density of states for the minority spin orientation. This semiconducting gap of ~1 eV opened up in the minority channel and is due to the large bonding–antibonding splitting from the p–d hybridization. Our findings suggest that the Mn-doped ZnSnAs₂ chalcopyrites could be a different class of ferromagnetic semiconductors

Engineering the magnetic and magnetocaloric properties of PrVO3 epitaxial oxide thin films by strain effects

Combining multiple degrees of freedom in strongly-correlated materials such as transition-metal oxides would lead to fascinating magnetic and magnetocaloric features. Herein, the strain effects are used to markedly tailor the magnetic and magnetocaloric properties of PrVO3 thin films. The selection of appropriate thickness and substrate enables us to dramatically decrease the coercive magnetic field from 2.4 T previously observed in sintered PVO3 bulk to 0.05 T for compressive thin films making from the PrVO3 compound a nearly soft magnet. This is associated with a marked enhancement of the magnetic moment and the magnetocaloric effect that reach unusual maximum values of roughly 4.86 uB and 56.8 J/kg K in the magnetic field change of 6 T applied in the sample plane at the cryogenic temperature range (3 K), respectively. This work strongly suggests that taking advantage of different degrees of freedom and the exploitation of multiple instabilities in a nanoscale regime is a promising strategy for unveiling unexpected phases accompanied by a large magnetocaloric effect in oxides.Comment: This paper is accepted for publication in Applied Physics Letter

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Ab initio study of structural, electronic and thermodynamic properties of tungstate double perovskites Ba₂MWO₆ (M = Mg, Ni, Zn)

The structural and electronic properties of the double perovskite Ba₂MWO₆ with M = Mg, Ni, Zn have been studied using the full-potential linearized augmented plane wave (FP-LAPW) method by employing both the local density approximation (LDA) and the generalized gradient approximation (GGA), which are based on exchange–correlation energy optimization to calculate the total energy. Also we have used the Engel–Vosko GGA formalism, which optimizes the corresponding potential for band structure calculations. However, we have evaluated the ground state quantities such as lattice parameter, bulk modulus and its pressure derivative. Also, we have presented the results of the band structures and densities of states. These results were in favorable agreement with previous theoretical works and the existing experimental data. To complete the fundamental characteristics of these compounds we have analyzed the thermodynamic properties such as thermal expansion coefficient, heat capacities and other structural parameters in the whole pressure range from 0 to 20 GPa and temperature range from 0 to 1000 K

Magnetocaloric effect in ternary ErAgAl: Ab initio, mean field and Monte Carlo approaches

ErAgAl has been known as an orthorhombic system of the CeCu2-type with ferromagnetic ground state. In this work, the magnetic and magnetocaloric effect has been studied using first principles calculations, Monte Carlo and Mean Field approaches. The adiabatic temperature change, the isothermal entropy change, and the relative cooling power (RCP) have been calculated. The Erbium magnetic moment calculated by FP-LAPW method is 8.21μB, in good agreement with experimental data. The compound exhibits a second order phase transition from paramagnetic to ferromagnetic state at Tc = 14 K. The isothermal entropy change (-ΔSMmax) reaches a maximum value equal to −12.24 J Kg−1 K−1 for a magnetic field of 6 T showing a large magneto-caloric effect around the Curie temperature with no obvious thermal and magnetic hysteresis loss in good agreement with experimental data. The obtained results make the compound suitable for magnetic refrigeration at low temperature regime. Keywords: Magneto-caloric effect, Relative cooling power, Electronic structure, Monte Carlo simulation, Ferromagnetis

On the origin of the giant magnetocaloric effect in HoMn2O5 single crystals: First principles study and Monte Carlo simulations

International audienc

Engineering the magnetocaloric properties of PrVO 3 epitaxial oxide thin films by strain effects

International audienc

Engineering the magnetocaloric properties of PrVO 3 epitaxial oxide thin films by strain effects

International audienceCombining multiple degrees of freedom in strongly correlated materials such as transition-metal oxides would lead to fascinating magnetic and magnetocaloric features. Herein, the strain effects are used to markedly tailor the magnetic and magnetocaloric properties of PrVO3 thin films. The selection of an appropriate thickness and substrate enables us to dramatically decrease the coercive magnetic field from 2.4 T previously observed in sintered PVO3 bulk to 0.05 T for compressive thin films making from the PrVO3 compound a nearly soft magnet. This is associated with a marked enhancement of the magnetic moment and the magnetocaloric effect that reaches unusual maximum values of roughly 4.86 μB and 56.8 J/kg K with the magnetic field change of 6 T applied in the sample plane in the cryogenic temperature range (3 K), respectively. This work strongly suggests that taking advantage of different degrees of freedom and the exploitation of multiple instabilities in a nanoscale regime is a promising strategy for unveiling unexpected phases accompanied by a large magnetocaloric effect in oxides