Comparison of 2D melting criteria in a colloidal system

We use super-paramagnetic spherical particles which are arranged in a two-dimensional monolayer at a water/air interface to investigate the crystal to liquid phase transition. According to the KTHNY theory a crystal melts in thermal equilibrium by two continuous phase transitions into the isotropic liquid state with an intermediate phase, commonly known as hexatic phase. We verify the significance of several criteria based on dynamical and structural properties to identify the crystal - hexatic and hexatic - isotropic liquid phase transition for the same experimental data of the given setup. Those criteria are the bond orientational correlation function, the Larson-Grier criterion, 2D dynamic Lindemann parameter, the bond-orientational susceptibility, the 2D Hansen-Verlet rule, the L\"{o}wen-Palberg-Simon criterion as well as a criterion based on the shape factor of Voronoi cells and Minkowski functionals. For our system with long range repulsion, the bond order correlation function and bond order susceptibility works best to identify the hexatic - isotropic liquid transition and the 2D dynamic Lindemann parameter identifies unambiguously the hexatic - crystalline transition.Comment: 20 pages, 13 figure

Playing the game: defining indicators for intact forest landscapes in the Congo basin

In 2014, the General Assembly of the FSC (Forest Stewardship Council) adopted Motion 65 that called for the protection of the vast majority of Intact Forest Landscapes (IFL) in FSC certified concessions around the Globe. To comply with Motion 65, a Regional Working Group for the Congo Basin on High Conservation Values (HCV-RWG) was established in 2016. To support its decision-making process, FSC invited a team of researchers as facilitators. The facilitation team associated Companion Modelling and MineSet. Companion Modelling is a participatory approach based on the development and use of role-playing games to support decision-making. MineSet, is a model of regional landscape change developed to explore the future of tropical forest landscapes in Central Africa over the next decades. MineSet places players in the roles of CEOs of logging and mining companies, interacting with markets, the government and NGOs, planning their activities and developing strategies to cope with the environmental, economic and social impacts of their decisions. It features all the major underlying drivers of land use change in Central Africa: demographics, economic and finance signals, governance and transparency, technological changes, and cultural differences. As the game unfolds, the players discover the complexity of the system, and devise new rules and strategies to balance development and conservation. The game and the discussion that follows enables stakeholders to share and confront their perceptions of the system, better grasp its complexities, explore alternative futures in a low-risk environment, and negotiate new forms of collective action. Taking on the role of a stakeholder has a profound impact on players' awareness and understanding of the system, and has the potential to reshape their perception on the problem at hand. This experience is a critical component of the approach and central to the learning process. Thanks to this combination, the RWG could unlock stalled negotiations, level the playing field between participants and move toward consensus. This example serves as proof of concept of the use of facilitation and games to address complex negotiations under conditions of high uncertainty and divergent interests. It shows a way to foster transformation in landscape management

Testing the role of SNe Ia for galactic chemical evolution of p-nuclei with two-dimensional models and with s-process seeds at different metallicities

Date of Acceptance: 07/11/2014The bulk of p isotopes is created in the "gamma processes" mainly by sequences of photodisintegrations and beta decays in explosive conditions in Type Ia supernovae (SNIa) or in core collapse supernovae (ccSN). The contribution of different stellar sources to the observed distribution of p-nuclei in the solar system is still under debate. We explore single degenerate Type Ia supernovae in the framework of two-dimensional SNIa delayed-detonation explosion models. Travaglio et al. discussed the sensitivity of p-nuclei production to different SNIa models, i.e., delayed detonations of different strength, deflagrations, and the dependence on selected s-process seed distributions. Here we present a detailed study of p-process nucleosynthesis occurring in SNIa with s-process seeds at different metallicities. Based on the delayed-detonation model DDT-a of TRV11, we analyze the dependence of p-nucleosynthesis on the s-seed distribution obtained from different strengths of the 13C pocket. We also demonstrate that 208Pb seed alone changes the p-nuclei production considerably. The heavy-s seeds (140 ≤A < 208) contribute with about 30%-40% to the total light-p nuclei production up to 132Ba (with the exception of 94Mo and 130Ba, to which the heavy-s seeds contribute with about 15% only). Using a Galactic chemical evolution code from Travaglio et al., we study the contribution of SNIa to the solar stable p-nuclei. We find that explosions of Chandrasekhar-mass single degenerate systems produce a large amount of p-nuclei in our Galaxy, both in the range of light (A ≤ 120) and heavy p-nuclei, at almost flat average production factors (within a factor of about three). We discussed in details p-isotopes such as 94Mo with a behavior diverging from the average, which we attribute to uncertainties in the nuclear data or in SNIa modeling. Li et al. find that about 70% of all SNeIa are normal events. If these are explained in the framework of explosions of Chandrasekhar-mass white dwarfs resulting from the single-degenerate progenitor channel, we find that they are responsible for at least 50% of the p-nuclei abundances in the solar system.Peer reviewedFinal Accepted Versio

Nanoscale Aspects of Corrosion on Cultural Heritage Metals

International audienceMetallic artefacts are an important part of the cultural heritage and must be protected for the future generations. Unfortunately, classical metal protection methods used for example in industry, can in most of cases not be used in the context of the conservation of cultural heritage because artefacts must not be aesthetically modified and any protection treatment must be potentially removable without any damage to the artefact. For that reason, to set up efficient conservation strategies, it is necessary to understand and model the long term corrosion mechanisms. In addition to environmental monitoring and empirical approaches, the fine understanding of the corrosion systems, based on the use of multiscale character-isation techniques and methodologies is a key issue to understand the mechanisms and evaluate the degradation rates. This chapter reviews the cases for which investigations at nano scales are necessary to understand and model in a reliable way the corrosion behaviour of different metals (ferrous alloys and bronzes). Nanoscale investigation, also allows scientists to understand the way intentional patinas were made on ancient bronzes. Lastly, an example of the use of nan-otechnology to set up an adapted and innovative protective treatment is given

KADoNiS-pp: The astrophysical pp-process database

The KADoNiS-$p$ project is an online database for cross sections relevant to the $p$-process. All existing experimental data was collected and reviewed. With this contribution a user-friendly database using the KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars) framework is launched, including all available experimental data from (p,$\gamma$), (p,n), (p,$\alpha$), ($\alpha$,$\gamma$), ($\alpha$,n) and ($\alpha$,p) reactions in or close to the respective Gamow window with cut-off date of August 2012 (www.kadonis.org/pprocess).Comment: Proceedings Nuclear Data Conference 2013, published in Nuclear Data Sheets 120 (2014) 19

The new p-process database of KADoNiS

The KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars) project is an online database (www.kadonis.org) for cross sections relevant to the s-process and the p-process. The first version was an updated sequel to the previous Bao et al. [1] compilations from 1987 and 2000 for (n; g) cross sections relevant to Big Bang and s-process nucleosynthesis. The first update, KADoNiS v0.2, was published in 2006 [2]. It contained mainly Maxwellian averaged (n; g) cross sections relevant to the s-process, and some experimental charged particle induced reaction relevant to the p-process. After that a second update was presented in 2009 [3]. Recently, we started to collect and review all existing experimental data relevant for p-process nucleosynthesis and to provide a user-friendly database based on the KADoNiS framework. The p-process part of the KADoNiS database is currently being extended and will include all available experimental data from (p; g), (p;n), (p;a), (a,g), (a;n) and (a; p) reactions in or close to the respective Gamow window