Ege Dundar

Justyna Rogacka

Lucyna Firlej

Carlos Wexler

Philip Llewellyn

Pascal Boulet

Bogdan Kuchta

Low temperature mechanism of adsorption of methane: Comparison between homogenous and heterogeneous pores

The mechanisms of methane adsorption in (i) homogeneous carbon slit pores of widths between 1 nm and 2 nm and (ii) heterogeneous MOF pores of similar unit cell sizes have been compared. We discuss the mechanism of layering transition in subcritical conditions, for temperatures between 80 K and 180 K. The layer formation is strongly temperature-dependent. In slit pores it varies from a sharp adsorption at low temperatures to a more continuous uptake at higher temperatures. The pore size defines the number of adsorbed layers: the 1 nm pore allows adsorption of 2 layers while the 2 nm pore allows adsorption of 5 layers of methane molecules. We compare this behavior with the mechanism of adsorption in two MOFs, IRMOF-1 and IRMOF-16, with strongly heterogeneous walls (both structurally and energetically). This comparison allows us to discuss separately the influence of wall topology and intermolecular interactions on the mechanism of layering.

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Introduction

In order to efficiently use adsorption-based processes in indus-trial applications it is crucial to fully understand the underlying fundamental adsorption mechanisms. Extended information about gas adsorption at ambient temperature is available in the literature [START_REF] Marco-Lozar | Gas storage scale-up at room temperature on high density carbon materials[END_REF][START_REF] Ma | Gas storage in porous metal-organic frameworks for clean energy applications[END_REF][START_REF] Wang | Mesoporous carbon originated from non-permanent porous MOFs for gas storage and CO2/CH4 separation[END_REF][START_REF] Millward | Metal-organic frameworks with exceptionally high capacity for storage of carbon dioxide at room temperature[END_REF][START_REF] Sweatman | Characterization of porous materials by gas adsorption at ambient temperatures and high pressure[END_REF]; however, it is also important, for a variety of microporous materials (like activated carbon, graphene and zeolites), to investigate the properties of low temperature adsorbed phases [START_REF] Benard | Storage of hydrogen by physisorption on carbon and nanostructured materials[END_REF][START_REF] Rouquerol | Adsorption by Powders and Porous Solids, Principles, Methodology and Applications[END_REF][START_REF] Cavenati | Adsorption equilibrium of methane, carbon dioxide, and nitrogen on zeolite 13× at high pressures[END_REF]. Methane adsorbed in confined geometries is interesting from both fundamental and practical points of view. At ambient temperatures supercritical adsorption is usually studied, as it is the most relevant for methane storage. At the same time, the analysis of methane's low temperature adsorption can provide a deep insight into the mechanism of adsorption as a function of industrially relevant parameters such as temperature, pore size, and pore topology.

In recent years, a new class of crystalline microporous materials has emerged: metal-organic frameworks (MOFs) [START_REF] Rowsell | Hydrogen sorption in functionalized metal-organic frameworks[END_REF][START_REF] Rosi | Hydrogen storage in microporous metal-organic frameworks[END_REF][START_REF] Eddaoudi | Systematic design of pore size and functionality in isoreticular mofs and their application in methane storage[END_REF]. MOFs are organic-inorganic materials showing a large spectrum of adsorption characteristics. The most remarkable is the modular approach used to synthesize them [START_REF] Fairen-Jimenez | Unusual adsorption behavior on metal-organic frameworks[END_REF]. The use of independent building units (organic linkers and metal nodes) offers a large synthesis flexibility and allows tailoring specific physical characteristics and chemical functionalities of these highly porous materials [START_REF] Walton | Understanding inflections and steps in carbon dioxide adsorption isotherms in metal-organic frameworks[END_REF]. MOFs belong-ing to the IRMOF family (IsoReticular metal-organic frameworks) [START_REF] Eddaoudi | Systematic design of pore size and functionality in isoreticular mofs and their application in methane storage[END_REF], have been identified as excellent candidates for methane storage, at room temperature and for pressures up to 42 bar (in the case of IRMOF-6). Some of them show unusual adsorption of methane, in which an evolution from type V isotherms at low temperature to type I isotherms at higher temperature has been observed [START_REF] Fairen-Jimenez | Unusual adsorption behavior on metal-organic frameworks[END_REF]. Grand canonical Monte Carlo (GCMC) simulations showed that this behavior results from relatively weak methane-pore wall interactions, which in turn, is a consequence of the relatively open nature of the MOF framework. The temperature at which transition from a type V isotherm to a type I isotherm occurs strongly depends on pore size, particularly for IRMOFs with smaller pores.

The properties of any adsorbed system are determined by the competition between two types of interactions: adsorbate-adsorbate and adsorbate-adsorbent. This competition defines, in particular, the shape of the isotherms and the structure of the adsorbed phase. The existence of an inflection point in the isotherm may be an indication that the adsorbate-adsorbate interaction is getting stronger than the adsorbate-absorbent one.

Capillary condensation in nanopores is another consequence of the domination of intra-adsorbate interactions. When the multilayer adsorption occurs in nanopores, the mechanism of the layer formation is also governed by this competition because the subsequent layers feel weaker attraction from the wall atoms. However, there is another important factor that influences the mechanism of adsorption: the heterogeneity of the adsorbent. The heterogeneity may modulate the energy competition and substantially modify the adsorption mechanism. For instance, the ordered monolayer is formed only in the case of a very homogeneous surface. In the case of strongly heterogeneous adsorbents the well-defined monolayers do not form and the notion of 'statistical monolayer' is used to describe the situation. In this paper we focus our analysis on the influence of pore wall heterogeneity on the mechanism of layer formation in micropores, that is, pores which can accommodate no more than five layers of methane molecules.

We present simulations of methane adsorption in two different adsorbents: graphene slit-shaped pores with homogeneous (smooth) pore walls and of effective widths between 1 and 2 nm, and two IRMOFs, IRMOF-1 and IRMOF-16 (see Fig. 1) (having pore sizes of 1.24 nm and 2.12 nm, respectively) characterized by very heterogeneous pore walls. The pore sizes are given as the distances between the wall-atom positions. Our goal is to analyze the influence of pore wall heterogeneity on the structural properties of methane adsorbed in MOFs. In particular, we compare the mechanisms of layering transition and possible occurrence of capillary condensation. Finally, we will point out that the pore filling in MOFs is an intricate process having some similarities to structural phase transition.

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Pore structures

The slit-shaped carbon pore walls have been modeled by a pair of parallel graphene layers. The size of the pores studied in this paper varied between 1nm and 2nm. The pore width has been defined as the distance between the centers of the carbon atoms in the graphene sheet. The CH 4 -graphene interaction has been described by the standard analytical Steele potential [START_REF] Kuchta | Hypothetical high-surface-area carbons with exceptional hydrogen storage capacities: open carbon frameworks[END_REF][START_REF] Kuchta | Numerical estimation of physical limits of hydrogen storage by physisorption in microporous nanospaces[END_REF][START_REF] Firlej | Enhanced hydrogen adsorption in boron substituted carbon nanospaces[END_REF][START_REF] Etters | Vacancy-induced melting of N2 adlayers on graphite[END_REF]. This potential assumes that a CH 4 molecule interacts with carbon atoms in the graphene sheet through the Lennard-Jones (6-12) potential and renders the energy of the adsorbed particle as an integral over the whole graphene sheet. To account for the atomic structure of graphite, the energy can be modulated by adding a corrugation term. However, atomic corrugation of the graphitic wall is not explicitly treated in this paper as it represents a small fraction of the CH 4 -wall interaction energy. Its influence is negligible for the total storage capacity [START_REF] Kuchta | Hypothetical high-surface-area carbons with exceptional hydrogen storage capacities: open carbon frameworks[END_REF][START_REF] Etters | Vacancy-induced melting of N2 adlayers on graphite[END_REF].

IRMOFs [START_REF] Eddaoudi | Systematic design of pore size and functionality in isoreticular mofs and their application in methane storage[END_REF] are three-dimensional cubic networks constructed from Zn 4 O coordination centers connected by dicarboxylate linkers. Two such structures have been chosen here to study CH 4 adsorption, IRMOF-1 (also called MOF-5) and IRMOF-16. The linkers used in these structures are benzene-dicarboxylate and triphenyl-dicarboxylate linkers, respectively [START_REF] Eddaoudi | Systematic design of pore size and functionality in isoreticular mofs and their application in methane storage[END_REF]. We used the crystallographic information files (.cif) for both IRMOFs from the Cambridge Crystallographic Data Centre (CCDC) website under codes CSD-175572 for IRMOF-1 and CSD-175585 for IRMOF-16 [START_REF] Eddaoudi | Systematic design of pore size and functionality in isoreticular mofs and their application in methane storage[END_REF][START_REF] Allen | The Cambridge Structural Database: a quarter of a million crystal structures and rising[END_REF]. Table 1 summarizes some key features for both IRMOFs while Fig. 1 gives graphical representations of their unit cells. The unit cell dimensions of both systems are comparable; the most important difference between them is that IRMOF-16's unit cell contains one pore (cage) of a single type and IRMOF-1's unit cell contains 8 pores (cages) of two different types. Fig. 1 shows the 2 × 2 × 2 supercells, with the crystallographic unit cells doubled in each direction.

The IRMOF walls are strongly heterogeneous, both energetically and structurally. This characteristic is illustrated in Fig. 2, which shows the difference between the distributions of CH 4 energy, when methane is adsorbed in the 1nm carbon slit pore and in IRMOF-1.

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Table 1: Key characteristics for IRMOF-1 and IRMOF-16 [START_REF] Eddaoudi | Systematic design of pore size and functionality in isoreticular mofs and their application in methane storage[END_REF].

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Fig. 2. Distributions of the interaction energy between CH 4 molecules and the pore wall in 1 nm slit-shaped pore (red, shaded distribution) and in IRMOF-1 (gray, solid distribution). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

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Simulation method

The computational approach was based on the GCMC simulations [START_REF] Frenkel | Understanding Molecular Simulations from Algorithms to Applications[END_REF] implemented in the Music software package [START_REF] Gupta | Object-oriented programming paradigms for molecular modeling[END_REF]. The MOF framework was considered rigid during simulations, meaning that its atoms were kept fixed at their crystallographic positions. All interatomic interactions were modeled using the Lennard-Jones (6-12) potential. The parameters for the framework atoms were obtained from the Universal Force Field (UFF) [START_REF] Rappe | UFF, a full periodic table force field for molecular mechanics and molecular dynamics simulations[END_REF]. The CH 4 molecules were considered as super atoms (united atom model). The CH 4 -CH 4 Lennard-Jones parameters were σ CH4 = 3.730 Å and ε CH4 = 148.0 K [START_REF] Goodbody | Molecular simulation of methane and butane in silicalite[END_REF]. Parameters describing fluid-solid interactions were obtained using the Lorentz-Berthelot mixing rules. The inter-actions were cut off beyond 12.8 Å [START_REF] Dü Ren | Design of new materials for methane storage[END_REF]. Due to the symmetry of the super atom representation of the CH 4 molecules, electrostatic forces were not considered in the simulations. Periodic boundary conditions were employed in all directions. All simulations were carried out at four temperatures: 80, 110, 140, and 180 K. Isotherm points were calculated by averaging the number of adsorbed molecules per unit cell of the material for a given chemical potential μ and temperature T. Each GCMC simulation was run for at least 60 million steps and consisted of insertion, deletion and displacement moves [START_REF] Gupta | Object-oriented programming paradigms for molecular modeling[END_REF]. Thermodynamic properties for bulk CH 4 were calculated with NIST's REFPROP application [START_REF] Lemmon | NIST standard reference database 23: reference fluid thermodynamic and transport properties-REFPROP, version 9.1[END_REF].

Results

Fig. 3 shows the evolution of the CH 4 adsorption isotherms in both systems: carbon slit pores and IRMOFs at T = 80, 110, 140, and 180 K. The isotherms show the number of molecules adsorbed in the pores. The volumes of the slit pores are 4.26 × 4.92 × 1.0 nm 3 for the smaller slit pore and 4.26 × 4.92 × 2.0 nm 3 for the larger slit pore. The volumes of the MOFs' cells have been normalized to vol-umes having the same xy base surface. The IRMOF-1 base surface (1.291 × 1.291 nm 2 ) has been used to represent the isotherms in Fig. 3.

The third dimension (z) has been defined by the pore sizes and was equal to 1.291 nm and 2.149 nm for IRMOF-1 and IRMOF-16, respectively.

Several differences between the CH 4 adsorption isotherms in both systems can be noted. First of all, the stepwise character of the isotherms, a characteristic of layer formation and observed in slit pores (Fig. 3, left panel), is modified in the IRMOF environ-ment (Fig. 3, right panel). Although the 1 nm slit pore and IRMOF-1 isotherms seem similar, the microscopic configurations of both structures are totally different. In the slit pore a regular mono-layer forms on each wall surface, whereas in IRMOF-1 the adsorbate structure evolution with pressure is much more complicated and shows a non-continuous reconstruction before the pores are filled up (see discussion below). The main factor responsible for these differences is the structure of the pore walls. At the temperatures studied here the graphene walls can be considered as homogeneous; their atomic corrugation has been neglected in the model of CH 4 pore wall interaction. At the same time, the IRMOF adsorbing walls are strongly heterogeneous within the crystallographic unit cell (Fig. 1) from both geometric and energetic points of view. The heterogeneity of the adsorption sites in IRMOFs is defined by the various atoms of the solid walls; the strongest adsorption sites are the metallic centers and the weaker ones are located on the organic linkers. Therefore we conclude that the similarity of adsorption isotherms in both systems is only apparent and is a consequence of the very small size of the IRMOF-1 pore which results in relatively strong energies of adsorption (Fig. 4). The mechanism of the layer formation is very different, as will be seen from the density evolution discussed below.

The influence of the adsorption sites' strong heterogeneity on the mechanism of adsorption is much more easily observed in larger pores. Methane adsorption in 2nm carbon slits gives rise to a stepwise isotherm; the resulting adsorbed structure consists of regular methane layers. In IRMOF-16 the stepwise adsorption is not observed at all. The first layer is formed in a very continuous way and over a relatively large range of pressure. It confirms that there is a distribution of adsorption energies in the system. At low temperatures (below 110 K), once the first layer covers the walls, the pore is rapidly filled up. At higher temperatures thermal fluctuations modify the mechanism of adsorption and all discontinuous changes disappear. This phenomenon is well known in nanopores where the critical points of transition depend on structural and energetic characteristics of the pore [START_REF] De Toni | Understanding the effect of confinement on the liquid-gas transition: a study of adsorption isotherms in a family of metal-organic frameworks[END_REF].

Analysis of the adsorption energies (Fig. 4) provides additional insight into the mechanism of adsorption. In slit pores, the absolute value of energy always increases when the first layer is formed. This is a consequence of the formation of ordered layers where absolute energy increases with the density of the layer. The average adsorption energy slightly decreases when the second layer is adsorbed in the 2nm pore. This decrease is a consequence of the smaller contribution of the adsorbate-adsorbent interactions, in particular for the second layer. The situation is different in IRMOFs. In IRMOF-1 the general trend is similar to the one observed in the 1 nm slit pore. However, due to the heterogeneous wall structure, the energy increase is more gradual. In IRMOF-16 the observed energy decrease is typical for heterogeneous surfaces. The filling of the pore is accompanied by a small discontinuous rise and then stabilization of the energy, indicating condensation of a liquid layer in the center of the pore. It is interesting to note that in both the 2 nm slit pore and IRMOF-16, the formation of the second layer shows many characteristics of capillary condensation. However, we do not want to call it capillary condensation because there is no way of form-ing a meniscus in the microporous space. It is rather an analog of the layering transition observed in the slit pores. At the same time, there is no layer which is formed because of the 3D symmetry (cubic in the studied case) of the porous framework. So, we observe that the rapid adsorption (at 80 and 110 K) which fills up the pore is a consequence of relatively strong methane-methane interaction which stabilizes the systems. Its mechanism is more similar to the structural phase transformations than to capillary condensation or layering transition. At higher temperatures the filling is more grad-ual due to the thermal fluctuations but the average energy always increases.

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The trends observed for the isotherms and energies have their source in the allowed methane microscopic configurations. Fig. 5 shows the cumulative density distribution of methane adsorbed in slit-shaped pores and in IRMOFs. As expected, the density in the slit pores does not show any qualitative evolution as a function of pressure. It forms well defined layers where the positions of the peaks remain unchanged. The situation is more dynamic in IRMOF pores where the positions of the peaks are pressure dependent. It means that the 3D order of adsorbate is adjusting itself to the quantity of adsorbed gas and they can change very rapidly with small pressure variation. A close analysis of the peak positions clearly indicates that the distribution of adsorbed molecules (density) undergoes structural transformations: its low and high pressure orders are very different, especially in the IRMOF-1 structure. Not only does the number of peaks change but their positions are also changing in a non-continuous way. Fig. 6 shows the spectacular transformation of the methane density distributions between 0.021 mbar and 0.025 mbar in IRMOF-1. In spite of a very small pressure variation, the adsorbate under-goes a discontinuous qualitative reconstruction. With increasing pressure, the symmetry of the methane structure changes. This transformation seems to indicate an evolution, as a function of pressure, of the distribution of accessible adsorption sites in the heterogeneous MOF structure. The transformation shows characteristics of a conventional structural phase transition.

The observed layering adsorption mechanism in the slit pores is coherent with the previous simulation by Miyahara and Gubbins [START_REF] Miyahara | Freezing/melting phenomena for Lennard-Jones methane in slit pores: a Monte Carlo study[END_REF][START_REF] Jiang | Layering, freezing transitions, capillary condensation and diffusion of methane in slit carbon pores[END_REF]. There are no structural changes which would lead to structures with different symmetry. Only solid-liquid transformations are possible within each layer. The observed transitions at 80 K in IRMOF-1 structure are much more intricate. Below 0.023 mbar there is already adsorbed methane which occupies less than 15% of the total capacity. The transformations above 0.023 mbar could be interpreted as formation of two contact layers (∼0.75 of the total capacity) followed by formation of the middle layer above 0.027 mbar, as it happens in the 1.3 nm slit pore (see the slit pore distribution in Fig. 5). However, in the MOF structure each step leads to a profound reconstruction of the lower pressure structure. It is visualized by the mass distributions (Fig. 5) and even better by the xy maps of the mass distribution shown in Fig. 6. The latter one proves that part of the volume which was already filled at lower pressure is rebuilt and another part of the unit cell is filled in. The detailed mechanism of this transition requires more fundamental studies.

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Conclusions

We have compared the mechanism of adsorption of methane in two types of microporous structures: carbon slit-shaped pores with homogeneous pore walls and heterogeneous MOF-type structures.

Methane adsorption progresses through typical layer-by-layer filling of the pores. This mechanism of layering transition, clearly observed in the slit pores [START_REF] Miyahara | Freezing/melting phenomena for Lennard-Jones methane in slit pores: a Monte Carlo study[END_REF][START_REF] Jiang | Layering, freezing transitions, capillary condensation and diffusion of methane in slit carbon pores[END_REF], is strongly modified in the MOFs with strongly heterogeneous walls where formation of the first layer is more gradual. At the same time, in MOFs, the adsorbate structure undergoes important density redistribution as a function of pressure. This feature is not observed in slit pores where the density distribution (the position of the maxima) is pressure-independent.

The microscopic mechanism of methane adsorption in IRMOF-1 is discontinuous. At low temperature (<140 K) methane fills the pore through a discrete number of states. These states are characterized by different distributions of methane density, as shown in Figs. 5 and6. The adsorption of the first layer in IRMOF-16 is continuous and shows typical characteristics of heterogeneous surfaces. The formation of the second layer shows characteristics of capillary condensation: when the pore is filled in, the condensate inside the pore is more strongly bonded than the monolayer structure. At higher temperatures (140 K and 180 K) the adsorption mechanism shows continuous filling of pores in both IRMOF-1 and IRMOF-16 systems.

Summing up, the mechanism of pore filling in IRMOF-1 and IRMOF-16 is complex and involves an important structural reconstruction of the adsorbed phase at 80 K and 110 K. This trans-formation is induced by an evolution of the preferred adsorption sites as a function of gas pressure. It shows some features characteristic of structural phase transitions in the 3D (bulk) systems: in particular, a modification of the adsorbate structure symmetry is observed. This transition occurs due to the ordered but strongly heterogeneous distribution of adsorption sites in MOFs and is not observed in structurally homogeneous slit pores. Comparing the slit and the MOF wall geometry, on can say that the structural changes of adsorbate in MOF are analogs of the layering transitions in the slit pores. However, due to the very heterogeneous walls, they lead to profound reconstruction of the already adsorbed structure.

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  F i g . 1 . G r a p h i c a l representations of the IRMOFs studied in this work: (left) IRMOF-1 and (right) IRMOF-16 (from the University of Liverpool's ChemTube3D website [20].) This figure shows the Monte Carlo boxes which are 2 × 2 × 2 c r y s t a l l o g r a p h i c supercell representations.

Fig. 3 .

 3 Fig. 3. Isotherms of CH 4 adsorption in (left): carbon slit pores with widths of 1.0 nm (full squares) and 2.0 nm (open circles), (right): IRMOF-1 (full squares) and IRMOF-16 (open circles). Temperatures from top to bottom are 80 K, 110 K, 140 K, and 180 K, respectively. N gives the number of methane molecules in a normalized volume having the same xy base surface (see text).

Fig. 4 .Fig. 5 .Fig. 6 .

 456 Fig. 4. Absolute values of CH 4 adsorption energies for (left): carbon slit pores with widths of 1.0 nm (full squares) and 2.0 nm (open circles), (right): IRMOF-1 (full squares) and IRMOF-16 (open circles). Temperatures from top to bottom are 80 K, 110 K, 140 K, and 180 K, respectively. ! ! ! ! ! ! !

Acknowledgment

ED would like to thank the PACA Region for financial support under the Exploratory Call; grant 'PACE' no. 2013 04267.


Guillaume Futhazar

From Climate to Biodiversity -Procedural transcriptions and innovations within IPBES in the light of IPCC practices

Describing IPBES 1 as simply an 'IPCC 2 for biodiversity' would be overly simplistic. Indeed, these two institutions have major differences that have been underlined on several occasions 3 . These differences are the result of fundamental structuring aspects: the respective themes of these institutions, the institutional context surrounding their establishment and their mandate.

Concerning their themes, it is no longer necessary nowadays to engage in a lengthy demonstration to illustrate that climate and biodiversity 4 are facing major crises that call for swift and global responses. However, although climate change is the prime example of a global crisis, biodiversity constitutes an element that is intrinsically linked to territories as each region has to deal with specific yet connected threats. Moreover, biodiversity is not uniformly distributed among territories. Some countries, known as 'mega-diverse', have a higher degree of biological diversity and a vast majority of these are developing countries. As such, we can see through this notion the resurgence of the South/North divide in environmental debates. This strong link between biodiversity and territories also allows for a salient influence of the concept of permanent sovereignty over natural resources. Debates and negotiations for the establishment of the IPBES Platform and within its fora are clearly heavily influenced by these eminently political and legal considerations. IPBES and IPCC were negotiated and established in very different institutional contexts. IPCC was founded prior to the adoption of the United Nation Framework Convention for Climate Change 5 and it even took part in discussions that lead to the Convention's adoption 6 , whereas 1 Intergovernmental Platform on Biodiversity and Ecosystem Services.

2 Inergovernmental Panel on Climate Change.

IPBES has had to fit into in a very crowded institutional environment. Major conventions on biodiversity and ecosystems have existed for decades and constitute a regime complex, which is understood as being an accumulation of overlapping regimes with no hierarchy 7 and various types of interaction 8 . Alongside to these conventions, several UN institutions are also actively working on this broad theme, most notably UNEP, UNDP, FAO and UNESCO (which are among the main IPBES partners). The establishment of IPBES therefore raises the necessary question of how it will interact with numerous actors of the system.

Finally, the IPBES mandate is not a simple reiteration of what IPCC does. Both IPCC and IPBES seek to periodically assess the state of knowledge for their respective themes, but IPBES goes further by providing innovative tools and advice for its members 9 . The Platform, based on its work on the different assessments, will produce a list of research priorities. It will also work on strengthening capacity building and identifying tools and methodologies for decision makers in order to achieve effective biodiversity governance. However, like IPCC, IPBES will not generate new knowledge on its own 10 . These several major differences highlight the fact that we must abandon the idea that IPBES is only a duplication of the IPCC experience on a different topic. Still, it would be irrelevant to completely disconnect these two institutions as they are obviously interlinked. The intervention of the IPCC ex-Chair Rajendra Pachauri during the 3 rd IPBES Plenary is an illustration, among others, of the links between the two bodies. Climate and biodiversity are also connected 7 Rausitalia, K., Victor, D., 'The Regime Complex for Plant Genetic Ressources', International Organization, vol. 58, n°2, 2004, pp. 277-309. 8 Orsini, A., Morin, J.F., Young, O., 'Regime Complexes: A Buzz, a Boom, or a Boost for Global Governance? ', Global Governance, vol. 19, 2013, pp. 27-39. 9 The detailed mandate of the IPBES is available on line: http://www.ipbes.net/policies-and-procedures.html (last accessed: 30/06/2015). 10 Functions, operating principles and institutional arrangements of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, p. 1, « The Platform […] should not directly undertake new research » elements and the biodiversity crisis will not be halted if the climate crisis is not dealt with 11 .

This situation has been underlined by the Millennium Ecosystem Assessment which demonstrated that climate change is one of the drivers of biodiversity loss and its impact will increase in the upcoming years 12 . Biodiversity is also a tool in the mitigation of climate change as healthy ecosystems can absorb carbon and reduce its accumulation in the atmosphere 13 .

Moreover, negotiators involved in the discussion for the establishment of IPBES have been clearly influenced by IPCC's experience despite stressing the differences between the two initiatives. Overall, we can see a tendency within IPBES to simultaneously differentiate itself from its model while also reaffirming its evident ties.

The purpose of the present contribution it so study how this complex situation has impacted the IPBES rules of procedure by comparing them with those that prevail within the IPCC framework. However, prior to this analysis, it is essential to establish a precise definition of the term 'procedure' in the context of this study.

 What is a procedure?

Most legal research is focused on a specific definition of the concept of procedure, based on its contentious aspect. Procedures are usually understood as being the rules shaping the trial process. However, in the present chapter, our understanding of the term is broader and closer to the general definition-basically the steps to follow in order to accomplish a certain task or achieve a specific result 14 . As such, this definition concerns the functioning of institutions and . 13 For more information on this topic, see: www.cbd.int/climate/intro.shtml (last accessed: 30/06/2015). 14 The Cambridge Online Dictionary gives the following definition: "the order or method of doing something". covers rules governing their internal functioning and shaping their activities. However, this definition does not provide any indication regarding the legal consequences of these procedures.

In the context of IPBES, a breach of the procedures would not have any legal consequences.

Neither the rights nor the obligations of member states would be impacted by a procedural breach and no third party could be seized with this matter in order to pronounce sanctions. Yet, this absence of legal consequence does not imply that the application of these procedural rules is optional. The Platform and any other relevant actors playing a part in the process are bound by them and their application ensures that the activities and productions of the Platform are perceived as being legitimate. Indeed, rules of procedure are the product of state consensus with states being the only parties entitled to adopt them within the Platform Plenary 15 . As a consequence of the consensus requirement, the Platform Plenaries generated lengthy negotiations in order to lay down the procedural aspect of this new institution. The rules of procedure are therefore the expression of the member states' expectations on how the Platform must work. Any production or activity that would overstep the procedural framework would consequently be rejected by the members. In short, compliance with the agreed procedures is the necessary condition for the legitimacy of the IPBES process towards its members, with legitimacy being understood as what is perceived as being fair, equitable and politically acceptable 16 .

The procedures not only ensure the legitimacy of the activities and deliverables of the Platform towards the member states, they also do so towards stakeholders. Indeed, procedures as well as all of the IPBES institutional characteristics (mandate, structure, and work programme) tend to 15 Rules of Procedure for the Plenary of the Platform, Rule 36, available online at: www.ipbes.net/policies-andprocedures.html (last accessed: 30/06/2015). 16 Koetz, T., Farrell, K., Bridgewater, P., Building better science-policy interfaces for international environmental governance: assessing the potential within the IPBES, International Environmental Agreements: Politics, Law and Economics, vol. 12, n°1, 2012, pp. 1-21, p. 3. fulfill three main criteria 17 : credibility 18 , relevance 19 and legitimacy. Therefore, this chapter also aims to determine whether the procedures of this young institution satisfy these principles.

In discussing the diffusion and adaptation of procedure from IPCC to IPBES, this chapter echoes the work of Alexander Ovodenko and Robert Keohane, who established a theoretical framework for institutional diffusion, which is understood as being, "the adoption in new or reformed institutions of institutional features already operating in other institutions, national, international or transnational" 20 . The authors identify two factors that must be taken into account when studying diffusion cases. The first factor is functional: an institutional characteristic, such as a rule of procedure, will be diffused if the two institutions face the same problem structure, have similar involved actors, and if the institutional characteristic being diffused is perceived as being successful 21 . However, this first factor is insufficient on its own to fully understand institutional diffusion and we must also take into account the political factor, which encompasses the different ideas, powers and interests coexisting within a system 22 . The two different sections of this chapter reflect these two factors. The first section illustrates the obvious influence IPCC has had on the establishment of the IPBES rules of procedure for functional reasons (I), and the second section highlights the procedural innovations of the Platform and attempts to explain them in the light of the Platform characteristics (II).

17 Functions, operating principles and institutional arrangements of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, p. 2, 'Be scientifically independent and ensure credibility, relevance and legitimacy through peer review of its work and transparency in its decision-making processes'. 18 Koetz, T., Farrell, K., Bridgewater, P., 'Building better science-policy interfaces for international environmental governance: assessing the potential within the IPBES', op.cit., p.3, "credibility reflects the perceived validity of information, methods and procedures provided and applied via a Science Policy Interface". 19 Idem, "relevance reflects the extent to which the work carried out within a SPI is responsive to the conditions and needs of the policy process". 20 Ovodenko, A., Keohane, R., 'Institutional diffusion in international environmental affairs ', Institutional Affairs, vol. 88, n°3, 2011, pp. 523-541, p. 524. 21 Ibid, p. 541. 22 Idem.

Overall this chapter hopes to add to the debate concerning the linkages between IPCC and IPBES 23 by using, as a starting point, elements that are seldom the focus of detailed analysis: rules of procedure. I -The influence of IPCC in the shaping of IPBES During the lengthy discussions that led to the establishment of IPBES, one main argument was put forward on several occasions, i.e. that the Platform is not a simple reiteration of IPCC.

During the Putrajaya meeting in 2008, the participants insisted on this aspect while also recognizing that IPCC could serve as a model in the debates on how to design the new institution 24 . This call for differentiation yet inspiration recurred at each meeting that addressed the creation of the Platform and even during the IPBES Plenary. For instance, during the Busan meeting in 2010, the fact that an information document on IPCC was distributed to the attendees is particularly significant as it illustrates the status of IPCC's experience in negotiators' minds 25 . This situation evidently led to several procedural transplantations from IPCC to IPBES. Firstly, the IPBES report drafting process (A) and secondly the conflict of interest policy (B).

A) The IPBES report drafting process

The IPCC report drafting process is the result of a slow process that began following its creation in the late 1980s 26 . Several political factors led IPCC to further elaborate procedures that would ensure the highest possible credibility for its reports. As such, the transplantation of these procedures in the context of IPBES is clearly an asset for the Platform, which is able to benefit from the vast experience of IPCC in this field. 23 See Beck (S.) et al., 'Towards a reflexive turn in the governance of global environmental expertise: the case of the IPCC and the IPBES ', Gaya, vol.23, n°2, 2014, pp. 80-87. 24 Earth Negotiation Bulletin (ENB), vol. 158, n°1, 2008. 25 UNEP/IPBES/3/INF/5, Background document on the Intergovernmental Panel on Climate Change. 26 Agrawala (S.), 'Structural and process history of the IPCC', op. cit.

A close look at the procedures of both IPCC and IPBES shows how similar they are, even to the point where some dispositions appears to be clear 'copy/paste' of IPCC rules. For instance, the procedure for the incorporation of reviews, which aims to ensure greater credibility and scientific soundness, is a practically identical step for both organizations (see figure 1).

IPCC 27 IPBES 28 This comparison could be made for several aspects of the drafting procedures, thus showing how the IPCC precedent has had a huge influence in the conceptualization of the Platform procedures. Obviously, aspects calling for adaption because of the Platform's specificity have been modified accordingly, but nevertheless there is clearly a high degree of similarity in the way both institutions produce their reports (as illustrated in figure 2). This transplantation is a token of credibility for the Platform. IPCC procedures have undergone the test of time and controversies, and they guarantee the current status of the Panel as a major scientific actor in the field of climate change. Hence, it can be hoped that this credibility will be as strong for the Platform. Dealing with conflicts of interest is of crucial importance in preventing a legitimacy and credibility crisis. Any report accused of bearing skewed information because of a conflict would be immediately rejected by both members and stakeholders. The existence of the conflict would be perceived as a breach of equity and justice and all related content of the report would be dismissed as being 'false' or at least not trustworthy.

Review

IPCC has gone through a severe crisis in recent years. The mistakes that were pointed out in its report and the strong opposition of opponents led the Panel to reflect on its procedures. The mandate given to the Inter Academic Council to produce an independent review of the Panel led to numerous changes 30 , including the adoption of procedures for the prevention and management of conflicts of interest in 2011 31 . These procedures were later incorporated in the IPBES framework during its third Plenary. This incorporation came at a crucial time when the Platform was already confronted with its first controversies. It was accused of promoting the interest of industry by allowing scientists involved in the pesticide production sector to be in charge of the drafting of chapters in the upcoming report on pollination 32 . The IPBES Secretariat responded to this accusation by stressing that the Platform procedures were suited to manage any situation that could lead to a conflict of interest 33 .

By analysing both procedures, we can once again see that the two institutions adopted similar approaches (see figure 3). Several definitions are taken from the IPCC framework and the overall mechanism is identical (establishment of a committee, requirement that experts fill in a form). However, caution is needed when claiming that these procedures are sufficient to ensure complete credibility. Indeed, the screening process of experts is far from being strict. The form the experts are required to fill in is very simple and request any information about, for instance, any previous professional ties that the expert may have had 34 . Moreover, the fact that these forms are kept secret by the Platform can be seen as a breach of transparency which might have an impact on the credibility of the process. Yet, total access to the form would be a breach of the experts' privacy. Finding balance on this issue is rather complicated and only time will tell if this rule of procedure is sufficient for efficient management of interests within the Platform. The list of similarities between the two institutions could go on at length and this first section makes no claim to be exhaustive. The purpose of this short list is to simply illustrate the degree of influence the Panel has on the day-to-day work of the Platform.

If the examples used underline the relevance of the functional factor of institutional diffusion, the next section illustrates the influence of external factors in the shaping of the procedural identity of the Platform. II -Distinction and innovationthe creation of a distinct procedural identity.

As previously stated, political factors are to be taken into account when studying institutional diffusion. The introduction of this chapter recalled the marked differences in the context of each institution. These contexts bear different interests, powers and ideas and have a significant influence on how the IPBES rules of the procedure are constructed. The present section aims at discussing how this context led to the adoption of procedural innovations but was also the cause of unwelcomed modifications of rules transplanted from IPCC to IPBES.

A -Ambitious procedural innovations

The most salient innovations concern the way the Platform interacts with its members and stakeholders. In order to promote legitimacy and relevance, IPBES has adopted procedures guaranteeing collaboration and openness. In this respect, the two most remarkable procedural aspects are the working program drafting process on the one hand and the formal institutional linkages with other partners on the other.

 Elaboration of the work programme

The way the Platform work programme is established illustrates how the numerous expectations of the actors involved in the creation of IPBES are taken into account.

In the IPCC framework, the way the work programme is set remains constant from one period to another. Each evaluation cycle will discuss three aspects of climate change: 1-the scientific evidence, 2-the impact, adaptation and vulnerability, and 3-mitigation. However, this consistency does not imply strict similarity between each Panel report. IPCC rules of procedure state that the exact outline of each evaluation cycle will be determined by experts from governments and observer organizations and Bureau members 37 . Once this outline is agreed by the Panel Plenary, the evaluation process is applied as previously described. Based on this rationale, IPCC has published five reports since its creation (roughly one every 5-6 years) and has contributed to strengthening scientific consensus on the role of mankind in climate change, while also highlighting available solutions to reduce or cope with a phenomenon that is a dire threat to all societies 38 . However, in the IPBES context, the work programme elaboration process allows for variation between evaluation cycles. Indeed, the exact content of the work programme is determined by the Multidisciplinary Expert Panel which relies on requests, suggestions and inputs from members, observers and stakeholders 39 . All of these requests are then synthesized by MEP in order to produce a first draft of the work programme that is subsequently discussed by members during the Plenaries and eventually adopted as the definitive work programme. In this synthesis process, priority is given to the requests of states while stakeholder requests, i.e. from international organizations, multilateral environmental agreements or NGOs, are considered as suggestions or inputs. This balance in favour of states is a logical repercussion of the intergovernmental aspect of the Platform. The outcome of this process resulted in the adoption of the first Platform work programme during the second Platform Plenary in 2014 40 . For instance, this supplementary step in drawing up a work programme, which does not exist in the IPCC framework, contributed to reaching an agreement on the regional scope of evaluations that the Platform intends to produce in the upcoming years, or even on the elaboration of a report on land degradation and restauration. This procedure highlights the Platform's efforts to take the wide range of expectations from its members and stakeholders into account. By doing so, the work programme is likely to be perceived as highly relevant. Moreover, states are not the only actors who expect the Platform to have useful outcomes. Biodiversity-related conventions, international organizations, NGOs and research institutions have the same expectations. Even though their inputs are not a priority when drafting the work programme, they are nevertheless taken into account by MEP. All of these procedural elements, if applied correctly, will be a strong asset for the relevance of the Platform. Hopefully the Platform will receive more requests, suggestions and inputs when the time comes to draw up a second work programme. Indeed, for an intergovernmental institution with over a hundred member states, it is unfortunate that only 10 states have made requests.

Although the work programme was discussed within the members and is therefore the result of consensus, higher member involvement in this first phase would increase the legitimacy and relevance of the next work programmes.

As illustrated by the work programme elaboration process, IPBES has links with numerous actors working on biodiversity and ecosystems governance. This important feature led to the adoption of several decisions to establish the Platform external relations management procedures.

 Formal ties with other actors of biodiversity and ecosystem governance.

The decisions adopted in 2015 illustrate the extent to which the implementation of the work programme is expected to be a collaborative effort. The place allocated for stakeholders within the Platform is a salient illustration of this aspect 42 . Indeed, member states invite stakeholders to organize themselves within an open-ended network in order to support the work of the Platform by helping with the nomination of experts or liaising with hard to reach stakeholders.

This call for greater involvement of the protean community of stakeholders is both praiseworthy and necessary as it tends to ensure credibility and legitimacy 43 . Even if this aspect cannot be perceived as procedural according to our understanding of the term, one aspect of its implementation is linked to the procedures for the establishment of strategic partnerships.

Indeed, the decision on the stakeholder engagement strategy calls for the adoption of a strategic partnership during the next Platform Plenary. In the context of our analysis, the rules of procedure adopted on this topic highlight how crucial the status of other actors of biodiversity and ecosystem governance is for IPBES 44 .

Strategic partnerships have several purposes, one of which is the creation of technical support units. Like IPCC, IPBES relies on these TSUs in charge of coordinating activities linked to the production of its deliverables. IPBES has already established such units with the support of UNESCO on the theme of indigenous and local knowledge 45 . This practice is yet another example of institutional transplantation from IPCC. However, IPBES is innovative on the administrative aspects of these TSUs 46 , which are established through very specific agreements which clearly state both the precise mandate of the unit and the responsibilities of the Platform and the unit. This aspect should allow for a more effective TSU governance in the coming years.

However, strategic partnerships are not only meant to establish TSUs. The decision on strategic partnerships also calls for formal collaboration with the other major multilateral environmental agreements in the field of biodiversity and ecosystems. Partnerships should facilitate mainstreaming of the Platform and MEA activities and avoid redundancy. This is also a way for the Platform to ensure the relevance of its activities towards MEAs 47 . On the other hand, in the IPCC context, the Panel has no formal framework of collaboration with UNFCCC. This issue has been addressed several times within IPCC and has yet to be definitively resolved 48 .

In its application of the decision on strategic partnership, IPBES relies on several types of legal instruments in order to formalize its relations with other institutions. Memorandums are frequently used. These pseudo-contracts remain a mystery in the field of legal studies 49 . Written in the form of a contract, they do not possess any legal strength and only allow for the formalization of cooperation principles between several actors. Yet, their contractual aspect often includes very precise articles on interpretation, entry into force, settlement of disputes and even denunciation.

The use of such instruments, which elude classical legal conceptions yet are so close to them, adds a supplementary dimension to the way IPBES interacts with its institutional environment as compared to IPCC. This is a very interesting example of how a procedural requirement translates into the use of quasi-legal or para-legal instruments. It will be important to check on a practical level how far this aspect will influence future development of the Platform.

In many respects, IPBES is innovative when it comes to its interaction with other actors of the regime. These innovations can be understood as a consequence of the very rich institutional landscape within which the Platform is established. However, besides those positive innovations, some worrying modifications have been made in the transplanted IPCC procedures that may undermine the credibility of the Platform.

B -An unfortunate change in the expert selection process

During the second Platform Plenary, criteria for the selection of experts were at the centre of a heated debate [START_REF] Pesche | Le Consensus d'Antalya: les avancées de la Plateforme Intergouvernementale scientifique et politique sur la biodiversité et les services écosystémiques (IPBES)[END_REF] . This question has a very important strategic aspect that led to an opposition between two rationales. On the one hand, some states, including China and Argentina, wanted total control over the nomination of experts, thus keeping any expert nominated by relevant institutions that did not have a formal endorsement by the state out of the process. This condition would put IPBES in a very different position than IPCC, where experts are nominated by both member states and relevant institutions [START_REF]A to the Principles Governing IPCC Work, Procedures for the preparation, review, acceptance[END_REF] . On the other hand, European Union states, with support from the attending observers, wanted a process similar to that of IPCC in order to nominate experts most able to ensure satisfactory implementation of the work programme.

The push towards state control over the nomination of experts was one of the crucial points of the second Plenary. The outcome of negotiations on this point gave rise to a convoluted solution whose application is not straightforward.

MEP members, nominated by member states according to a geographical balance 52 , have the responsibility of selecting experts in charge of the drafting each work programme report. They do so by relying on a list of experts nominated by both governments and relevant institutions.

However, the selection has to respect a very precise balance that calls for a quota of 80% of government nominated experts and 20% of experts from relevant institutions 53 . Following this rule of procedure, if a report requires 100 experts to be drafted, 80 of them have to be government nominated.

This procedural requirement illustrates the extent of the stakes associated with biodiversity and ecosystems, most notably state sovereignty and the South/North divide. For instance, states in favour a higher control over the expert selection process claimed that it was of the highest importance that evaluations concerning their biodiversity and ecosystems be led by their own experts. This situation clearly demonstrates how difficult it is to focus on scientific aspects alone in international negotiations even when the rights and obligations of states are not directly concerned. In summary, this is a case of diffusion from IPCC to IPBES but with a modified outcome due to the ideas and interests of specific states in the Platform context.

This procedural aspect leads to obvious practical issues. Its strict application makes it hard to achieve the required number of selected experts. The IPBES Secretariat highlighted this problem in its report on implementation of the work programme and suggested to member states that they should reconsider this procedural rule 54 . For most European states, this 80/20 requirement does not constitute a severe obstacle for the nomination and selection of experts as they often closely collaborate with their own national institutions when nominating experts.

However, in other regions, most notably Eastern Europe, this rule of procedure hinders the selection process. For instance, when a group of states has not nominated a sufficient number of experts to reach the required 80%, it is necessary to call for additional nominations within this group. These 'default' nominations can be a drawback for the credibility of the Platform as the involved experts might not be as qualified or motivated as the stakeholders and observers hope them to be. This can also be a threat to the quality of the deliverables in which those experts were involved.

54 IPBES/3/2, Implementation of the Work Programme for 2014-2018, p.4, "Considering revisiting the requirement of 80% of selected experts having to come from government nominations to make it a less stringent requirement. This would potentially reduce the need for requesting governments for additional nominations".

Moreover, considering the fact that the nomination of experts is already influenced by the heavy pro bono workload that the involvement in the IPBES process represents 55 , one can only be sceptical towards this procedural aspects that may even further limit the involvement of qualified and willing experts. As such, this rule of procedure appears to be in contradiction with state expectations for the Platform. Indeed, during the second and third Plenaries, on numerous occasions states pointed out that the work programme may be too ambitious and too heavy on

IPBES. Yet, even though they were fully aware of this aspect, several of their decisions on the budget or the procedures ended up being more of an impediment than a support for the Platform.

The fact that they did not wish to change the 80/20 requirement for the selection of experts illustrates this ambiguous discourse by Platform members who ask so much of it while reducing its capacity. We will have to wait until the end of the first work programme to determine whether or not this analysis is too pessimistic, but from a theoretical standpoint, this procedural adaptation is a cause for concern.

***** This chapter has described a situation that is simply a logical reflection of the external elements which have shaped the establishment of the Platform. To overlook the IPCC case would have meant overlooking the wealth of experience amassed over time and by weathering the storms of controversy. How could one not acknowledge this institution when the initial idea for the creation of the Platform was to form an 'IPCC for biodiversity'? Not taking these precious lessons into account would have been a serious mistake. The current IPBES rules of procedure are, as such, very similar to those of IPCC. This does not mean however that IPBES is bound to simply be copy of IPCC.

55 IPBES/1/INF/15, Preliminary review of the motivations for participating in Platform assessments.

IPBES is innovative in several ways. Although this chapter was focused on its procedure, the Platform also adopted some very interesting governance tools, such as the 'conceptual framework' 56 . This framework illustrates how IPBES differentiates itself from IPCC not only by its procedure but also by the concepts upon which its work relies. Whereas IPCC is currently working on how to integrate traditional and local knowledge in its work, this theme was integrated very early in the IPBES framework via the conceptual framework. Even though this framework is not within the scope of our analysis, illustrating how distinct IPBES is from IPCC would have been incomplete without referring to this aspect.

Some observers consider that currently IPBES activities are too similar to those of IPCC and that it should seek to differentiate itself more 57 . This opinion is based on the fact that half of the IPBES budget is allocated to the evaluation function of the Platform, whereas the other half is divided among its other functions. However, considering the rules of procedure of the Platform and its context, it could be expected that in the years to come IPBES will develop in a very different way from IPCC. Now that the Platform has 'started working', it will forge its own identity. Moreover, the two institutions actually have started exchanging on several topics and the purpose of these exchanges is not only for IPBES to learn from IPCC. During its recent Plenary in Nairobi, IPCC took the practice of IPBES concerning its TSUs into account and suggested that its members should adopt new procedures based on this model 58 . Even though this proposal was turned down due to the lack of perspective on the long term application of these rules of procedures 59 , it goes to show that future relations between these two institutions will surely be based on mutual learning. This perspective of coevolution is a good sign as it will Bulletin, vol. 12, n° 67, 2015. participate in elevating the work standards and also contribute to ensuring the highest credibility, legitimacy and independence.

Yet, the Platform is not above criticism. The criteria adopted for the selection of experts, its relatively low budget and heavy workload may hinder implementation of its work programme.

As such, before putting forward hypotheses on the future influence of the Platform on IPCC, it is essential to first follow its initial process and assess its outcome. The adoption of its first reports in February 2016 will be a first trial and will pave the way for its future development.

Although this chapter has analyzed the influence of various external elements, it cannot offer any definitive proposals on the future of the Platform. It would be safe to assume that it will forge its own institutional identity since its mandate and procedures are obviously distinct from its model. However, considering the very ambitious work programme set by its members and the numerous obstacles it has to overcome, the prospects give cause for concern. The next meeting in Kuala Lumpur may provide answers to all of these interrogations.

  process. Thirdly, the review process should be objective, open and transparent.

Figure 1 :

 1 Figure 1: Comparison of procedures for the incorporation of comments in the drafting of

Figure 2 :

 2 Figure 2: Writing and review procedures for IPCC and IPBES Left diagram: IPCC process (source: www.ipcc.ch) Right diagram: IPBES process (simplified version by the author)

  §. 11: A 'conflict of interest' refers to any current professional, financial or other interest which could: i) significantly impair the individual's objectivity in carrying out his or her duties and responsibilities for the IPCC, or ii) create an unfair advantage for any person or organization. For the purposes of this policy, circumstances that could lead a reasonable person to question an individual's objectivity, or whether an unfair advantage has been created, constitute a potential conflict of interest. These potential conflicts are subject to disclosure. §. 11: For the purposes of this policy,

Figure 3 :

 3 Figure 3: Partial comparison of the IPBES and IPCC conflict of interest policies.

Figure 4 :

 4 Figure 4: Overview of requests, suggestions and inputs received by the Platform for elaboration of the first work programme 41

43

  However, stakeholders are left to their own devices to establish the open-ended network. Because of their number and the absence of a clear and centralized centre of organization, it is hard to determine at this point what the open-ended network will look like. 44 IPBES/3/ L.8, Strategic Partnerships. 45 IPBES/3/INF/13, Report on the institutional arrangements established to operationalize technical support. 46 As illustrated by the discussion on this aspect within IPCC. See IPCC-XLI/Doc. 4, Consideration of recommendations by the task force group on Future Work of IPCC, p. 5.

representation of independent experts (i.e. experts not involved in the preparation of that particular chapter) from developing and developed

	in	the	review	process,	ensuring

Three principles governing the review should be borne in mind. First, the best possible scientific and technical advice should be included so that the IPCC Reports represent the latest scientific, technical and socioeconomic findings and are as comprehensive as possible. Secondly, a wide circulation process, ensuring countries and countries with economies in transition should aim to involve as many experts as possible in the IPCC 3.6.4 Review Three principles govern the review process: first, the Platform reports should represent the best possible scientific, technical and socioeconomic advice and be as balanced and comprehensive as possible. Second, as many experts as possible should be involved

representation of independent experts (i.e., experts not involved in the preparation of the chapter they are to review) from all countries. Third, the review process should be balanced, open and transparent and

	adoption	approval	and	publication	of	IPCC	reports,	online	at:

record the response to each review comment.

27

Appendix A to the Principles Governing IPCC Work, Procedures for the preparation, review, acceptance, www.ipcc.ch/organization/organization_procedures.shtml (last accessed: 30/06/2015). 28 IPBES/3/L.2, Procedures for the preparation of Platform deliverables.

  30 Inter Academic Council, 'Climate change assessments Review of the processes and procedures of the IPCC', IAC Secretariat, Amsterdam, 2010, 104 p. 31 See Report of the 33 rd Session of the IPCC, Abu Dhabi, United Arab Emirates,May 10-13, 2011, p. 4.

32

Hochkirch, A., McGowan, P., Van Der Sluijs, J., 'Biodiversity reports need author rules', Nature, vol. 516, 2014, p. 170.

33

Larigauderie, A., 'Pollinator assessment: IPBES responds on conflicts of interest

', Nature, vol. 517, 2015, p. 271.

it pay special attention to issues of independence and bias in order to maintain the integrity of, and public confidence in, its products and processes. It is essential that the work of the IPCC is not compromised by any conflict of interest for those who execute

  The fact remains that only IPBES is able to determine whether or not a conflict of interest is real or not, which might fuel dissent amongst observers.

	IPCC 35	IPBES

36

§. 2: The role of the IPCC demands that it §. 2: The role of the Platform requires that

it pay special attention to issues of independence and bias in order to maintain the integrity of, and public confidence in, its products and processes. It is essential that the work of the Platform is not compromised by any conflict of interest for those who execute it.

34 IPBES/3/L.6, Conflict of interest policy and implementation procedures, p. 8.

35

IPCC Conflict of interest policy, online at: www.ipcc.ch/organization/organization_procedures.shtml (last accessed: 30/06/2015). 36 IPBES/3/L.6, Conflict of interest policy and implementation procedures.

  56 IPBES/2/4, Conceptual Framework for the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services. For a detailed analysis, see Diaz, S. et al., 'A Rosetta Stone for Nature's Benefits to People', PLOS Biology, vol.13, n°1, 2015, pp. 1-8. 57 Brooks, T.M., Lamoreux, J.F., Soberon, J., 'IPBES≠IPCC', op. cit. 58 IPCC-XLI/Doc. 4, Consideration of the recommendations by the task force group on Future Work of the IPCC, p. 5.

59

Earth Negotiation

Appendix A to the Principles Governing IPCC Work, Procedures for the preparation, review, acceptance, adoption approval and publication of IPCC reports, section 4.1.

* PhD candidate on contract for Labex OT-MED (ANR-11-LABX-0061) under the supervision of CERIC (CERIC-CNRS UMR 7318, Aix Marseille University, France).

This chapter is a contribution to the CIRCULEX project (ANR-12-GLOB-0001-03 CIRCULEX), funded by the French National Research Agency, which is devoted to studying the circulation of international environmental governance norms and actors.


Carole Ortega

Eric Lasseur

François Guillocheau

Olivier Serrano

Evolution of sedimentary architecture in retro-foreland basin: Aquitaine basin example from Paleocene to lower Eocene

come

Evolution of sedimentary architecture in retro-foreland basin: Aquitaine basin example from Paleocene to lower Eocene.

Carole Ortega, Eric Lasseur, François Guillocheau, Olivier Serrano and David malet The Aquitaine basin located in south western Europe, is a Pyrenean retro-foreland basin. Two main phases of compression are recorded in this retro-foreland basin during the Pyrenean orogeny. A first upper Cretaceous phase corresponding to the early stage of the orogeny, and a second one usually related to a Pyrenean paroxysmal phase during the middle Eocene. During Paleocene to lower Eocenedeformations are less pronounced, interpreted as a tectonically quiet period.

The aim of the study is to better constrain the sedimentary system of the Aquitaine basin during this period of Paleocene-lower Eocene, in order to discussthe evolution of the sedimentary architecture inresponse ofthe Pyrenean compression. This work is based ona compilation of a large set of subsurface data (wells logs, seismic lines and cores logs) represented byisopachs and facies map.

Three main cycles were identified during this structural quiet period:

(1) The Danian cycle, is recorded bythe aggradation of carbonate reef-rimmedplatform. This platform is characterized by proximal facies (oncoid carbonate and mudstone with thalassinoides) to the north, which leads to distal deposit facies southern(pelagic carbonate with globigerina and slump facies) and present a significant thickness variation linked to the platform-slope-basin morphology.

(2) The upper Selandian-Thanetiancycle follows a non-depositional/erosional surface associated with a Selandian hiatus.The base of this cycle marked the transition between the last reef rimmed platform and a carbonate ramp.

Thetransgressive cycle is characterized by proximal lagoon facies to the north that leads southwardto distal hemipelagic faciesinterfingeredbyturbiditicLowstand System Tracks (LST). The location of these LST isstrongly controlled by inheritedDanian topography.

The regressive cycle ends with a major regression associated with an erosional surface. This surface is linked witha network of canyons in the north, an important terrigeneous LSTand a massive erosional surface in deep basin.

We correlated this upper Thanetianmajor regression with a flexural deformation of the basin. In this context, the importance of terrigeneous LST could be explained by the erosion of the East Pyrenean range.

(3) The lower Ypresian recordsthe installation ofmixed terrigenous-carbonated system.While theEast-West progradation ofsiliciclastic deltas is drained into foreland basin, a carbonates condensation are developed on structural ridges, attesting the structural activation of foreland basin during lower Ypresian.

This study shows thatDanian to middle Thanetian time represents a quiet tectonic period in the retro-foreland basin. During the upper Thanetian period, the compressive deformation is increasing, marked by the emersion of the northern platform, a massive LST in deep basin anda riseof terrigenousinput in flexural basin (LST). This deformation associated with the Pyrenean compression continues during the Ypresian and highlights the paroxysm of the Pyrenean orogeny. This work is included in the Gaia project founded by TIGF, BRGM and Agence de l'Eau Adour/Garonne whose aim at constrain the nature and dynamics of deep Upper cretaceous and Tertiary aquifers of the Aquitaine basin.


K Theuwissen
email: koenraad.theuwissen@ocas.be

L Laffont

M Véron

J Lacaze

Keywords: Graphite growth, Heterogeneous nucleation, Crystal orientation, Transmission electron microscopy

Crystallography of graphite spheroids in cast iron

To further understand graphite growth mechanisms in cast irons, this study focuses on the crystal structure of a graphite spheroid in the vicinity of its nucleus. A sample of a graphite spheroid from a commercial cast iron was characterised using transmission electron microscopy. The chemical composition of the nucleating particle was studied at the local scale. Crystal orientation maps of the graphite spheroid revealed misorientations and twist boundaries. High resolution lattice fringe images showed that the basal planes of graphite were wavy and distorted close to the nucleus and very straight further away from it. These techniques were complementary and provided new insights on spheroidal graphite nucleation and growth.

Introduction

Since the discovery of the graphite spheroidisation treatment in cast irons, much research has been carried out to understand the development of spheroidal graphite precipitates. Various spherulitic growth models have been proposed, [START_REF] Hillert | The growth of nodular graphite[END_REF][START_REF] Sadocha | The mechanism of graphite spheroid formation in pure Fe-C-Si alloys[END_REF][START_REF] Double | Cone-helix growth forms of graphite[END_REF][START_REF] Miao | Structure and growth of platelets in graphite spherulites in cast iron[END_REF][START_REF] Faivre | On the mechanisms of spherulitic growth in polymer and iron melts[END_REF][START_REF] Double | The nucleation and growth of graphite. The modification of cast iron[END_REF] but the formation of this peculiar morphology remains unclear. The first step to understand this phenomenon is nucleation, and the general agreement is that graphite nucleates heterogeneously on foreign particles issued from the inoculation treatment. Several studies have focused on the nature of the nuclei: non-metallic inclusions have been found at the centre of graphite spheroids and have thus been considered as nucleation sites for graphite. The nucleation potential of these inclusions has been related to mismatch between their lattice parameters and that of graphite. The main types of nuclei quoted in the literature are salt-like carbides such as CaC 2 [START_REF] Lux | On the theory of nodular graphite formation in cast iron -Part I: experimental observations of nodular graphite formation during the solidification of cast iron melts[END_REF][START_REF] Lux | On the theory of nodular graphite formation in cast iron -Part II: theoretical interpretation of the experimental observations[END_REF] and various combinations of sulphides, oxides and silicates. [START_REF] Jacobs | Basic processes controlling the nucleation of graphite nodules in chill cast irons[END_REF][START_REF] Jacobs | Identification of heterogenous nuclei for graphite spheroids in chill-cast iron[END_REF][START_REF] Lalich | Characterization of inclusions as nuclei for spheroidal graphite in ductile cast irons[END_REF][START_REF] Francis | Heterogeneous nuclei and graphite chemistry in flake and nodular cast irons[END_REF][START_REF] Skaland | A model for the graphite formation in ductile cast iron: Part I. Inoculation mechanisms[END_REF] It has been stated that the same type of exogenous nuclei can produce both flake and spheroidal graphite, suggesting that the growth process determines the morphology of the graphite precipitates. [START_REF] Jacobs | Identification of heterogenous nuclei for graphite spheroids in chill-cast iron[END_REF][START_REF] Francis | Heterogeneous nuclei and graphite chemistry in flake and nodular cast irons[END_REF][START_REF] Ostberg | Perspectives on research on the formation of nodular graphite in cast iron[END_REF][START_REF] Velichko | Quantitative 3D characterization of graphite morphologies in cast iron using FIB microstructure tomography[END_REF] This paper illustrates the growth of a graphite spheroid from a nucleating particle as imaged by transmission electron microscopy.

Experimental

The investigated spheroidal graphite cast iron is a standard ferritic alloy used in previous work [START_REF] Valle | Effect of various dopant elements on primary graphite growth[END_REF] and containing mainly 3.64 wt-%C and 2.05 wt-%Si (Table 1). Nodularising treatment was made by the sandwich method using a 50 kg capacity ladle, at the bottom of which was placed 1.3 wt-% of a FeSiMg alloy (42-44 wt-%Si, 5-6 wt-%Mg, 0.9-1.0 wt-%Ca, 0.4-0.5 wt-%Al, 0.9-1.1 wt-%RE). The alloy was cast in chemically bonded sand moulds that contained standard keel blocks as described elsewhere. [START_REF] Asenjo | Microstructure investigation of small-section nodular iron castings with chunky graphite[END_REF] Inoculation was carried out by adding 0.15 wt-% of a mm alumina suspension at 400 mm [START_REF] Double | Defects in eutectic flake graphite[END_REF] and their mean diameter at 19 mm.

Results and discussion

Figure 2 is a photomontage of bright field images showing a complete view of the sample. The central part of the sample shows a different contrast than that of the rest of the sample, which is shown enlarged in Fig. 3. These figures show that conical sectors radiate outwards from this Automated crystal orientation mapping (ACOM) was carried out in a JEOL 3010 TEM at the SIMaP laboratory, operated at 300 kV, equipped with a DigiStar external source with step size of 17 nm. This technique enables investigation of crystal orientations at high spatial resolution based on electron diffraction patterns. [START_REF] Rauch | Coupled microstructural observations and local texture measurements with an automated crystallographic orientation mapping tool attached to a tem[END_REF][START_REF] Rauch | Automatic crystal orientation and phase mapping in TEM by precession diffraction[END_REF] Moreover, difficulties in determining crystal orientations of carbon-based materials found with other techniques such as EBSD can be overcome using ACOM.

A transmission electron microscopy TEM specimen was extracted from this sample. In order to obtain a diametrical (FIB) scanning electron microscope (SEM) a was used. Figure 1 shows the area for extraction of the specimen using the FIB lift-out technique. TEM investigation was carried out using a JEOL JEM-2100F transmission electron microscope at the Temscan service of Paul Sabatier University, operated at 200 kV. This microscope was equipped with a Bruker Quantax silicon drift detector, which enabled-energy dispersive X-ray analysis (EDX). section of the spheroid, a JEOL JIB-4600F focused ion beam commercial inoculant (68.1 wt-%Si, 0.89 wt-%Al, 1.65 wt-%Ca, 0.45 wt-%Bi, 0.38 wt-%Ba, 0.37 wt-%RE) into the cavity of the mould. A sample of this iron was ground and mirror polished with a 0.05 for metallographic examination. The graphite precipitates were of high nodularity; their surface density was evaluated * central area, strongly suggesting that the central part of the specimen corresponds to a nucleating particle.

The bright field image of the central area (Fig. 3) shows the clear difference in contrast between the nucleus and the surrounding graphite, as well as contrast differences between several parts of the nucleus. Energy dispersive X-ray analyses were performed at various locations in the central area and showed that the chemical composition of the nucleus is not homogeneous. It is relevant to note that sulphur content was not evaluated in this study because the sample was mounted on a molybdenum holder, whose La1 X-ray line produces a severe overlap with the Ka1 of sulphur.

The results are presented in Table 2, where it is seen that the inner part of the nucleus contains mainly Mg and Ca (the reported C values may not be significant except for the measurement #9 in graphite). Discrete particles at the periphery of the nucleus may be sorted as either Fe rich or Mg rich. These latter particles do contain Bi, La and Ca as well. Only in one occasion was oxygen detected at a significant level (particle #1), but it is not possible to ascertain that graphite nucleated at that location, i.e. to confirm that graphite nuclei are duplex sulphide oxide particles. [START_REF] Jacobs | Identification of heterogenous nuclei for graphite spheroids in chill-cast iron[END_REF] Given the shape of the observed particles, it is unlikely that a continuous oxide shell surrounds the core of the present nucleus as has been reported in the case of nuclei with duplex compositional structures.

Spectra were also taken on graphite in the vicinity of the nucleus, as seen in point 9 of Fig. 3. Elements from the nucleus were not detected at any significant level within graphite, suggesting that the particle serves solely as a nucleant.

The crystallographic features of graphite were investigated by means of selected area electron diffraction patterns, which were taken at different locations around the nucleus using an aperture with a 250 nm diameter as shown in Fig. 4. These patterns show several (0002) spots or diffraction arcs revealing different c axes orientations in the selected areas and their relative misorientations can be measured directly on the diffraction patterns. This information was used to identify several growth sectors according to the orientation of the c axes of graphite. For clarity, the apparent boundaries between sectors were drawn in the bright field image of Fig. 4, and only the (0002) spots were labelled in the corresponding diffraction patterns.

In order to have a general view of the orientations of graphite, ACOM measurements were carried out over an area of *4 mm around the nucleus. Figure 5 shows orientation maps projected along two different axes. The overall conical shape of the orientation domains is seen, and misorientations are revealed by the colour changes. These can be considered as growth defects (tilts or twists as defined in earlier studies of graphite crystals [START_REF] Austerman | Growth and characterization of graphite single crystals[END_REF] ). Measurements proved that the misorientations values around the nucleus are relatively small, mainly 5u to 10u and 11u to 13u. In some cases, higher misorientation values were observed within sectors: the changes from green to blue in Fig. 5a correspond to rotations of 27.5u and 25.8u around the c axis of graphite. The rotation angles close to 27u reported here correspond to low energy stacking faults in graphite as reported experimentally and predicted by the coincidence site lattice theory [START_REF] Double | Cone-helix growth forms of graphite[END_REF][START_REF] Minkoff | Rotation boundaries and crystal growth in the hexagonal system[END_REF][START_REF] Double | Defects in eutectic flake graphite[END_REF][START_REF] Roviglione | X-ray diffraction characterization of flake and compacted graphite in cast iron[END_REF] and could provide sites for atom attachment on prismatic planes as suggested for the growth of graphite flakes. [START_REF] Minkoff | Graphite growth from the melt[END_REF]

Conclusions

A thin foil specimen was extracted from a graphite spheroid and was studied by means of transmission electron microscopy. The presence of a foreign particle at the centre of the specimen was regarded as evidence that this was a diametrical section of the spheroid, well suited for a nucleation and growth study. The chemical composition of the nucleus was not homogeneous: the central part contains mainly Ca and Mg, whereas discrete particles rich in either Fe or Mg appeared at the outer surface of the nucleus.

Crystal orientation maps revealed the extent of sectoral growth from the nucleating particle. Misorientations were observed, and the identification of rotation boundaries at several locations in the sample seems closely related to the mechanism of spheroidal growth as they are much less observed in lamellar growth. [START_REF] Theuwissen | Etude de l'influence des impurete ´s et des e ´le ´ments a `l'e ´tat de traces sur les me ´canismes de croissance du graphite dans les fontes[END_REF] The visualisation of graphene layers using high resolution TEM showed their extensive deformation in the vicinity of the nucleating particle.

Studying the structure of graphite in the vicinity of the nucleus in other types of precipitates would be of interest to understand how the first stages of growth lead to the development of different graphite morphologies, but the main difficulty lies in locating the nucleus to produce appropriate TEM specimens.

The structure of graphite close to the nucleus was further studied using 0002 lattice fringe imaging mode for direct visualisation of the graphene layers. Micrographs such as the one presented in Fig. 6a show that graphene layers are often bent and curved in the vicinity of the nucleus leading to orientation changes as shown in the corresponding fast Fourier transform (FFT) of the image in the insert. This could be explained by the fact that such rippling occurs at the interface between neighbouring sectors, as reported elsewhere. [START_REF] Theuwissen | Etude de l'influence des impurete ´s et des e ´le ´ments a `l'e ´tat de traces sur les me ´canismes de croissance du graphite dans les fontes[END_REF] As several sectors grow from the nucleus (Fig. 4) their junction will inevitably lead to defects and consequently misorientations. The image in Fig. 6b was taken at about 1.5 μm from the nucleus, and shows relatively straight fringes with few defects and its FFT (insert) shows accordingly one main orientation.

9 *Table 2

 92 N.D.: no-detected. 4 Identification of growth sectors using selected area electron diffraction 5 Crystal orientation maps of graphite in central part of specimen. Projections a along sample's normal direction and b along Corresponding to the areas numbered in figure 3 EDX analyses*/at-% horizontal sample's length 1.3

Table 1

 1 Sample composition

	Element C	Si	Mn P	S	Mg	Cu Fe
	wt-%	3.64 2.05 0.11 0.033 0.015 0.037 0.04 Bal.

1 Images (SEM) illustrating sample preparation using FIB lift out technique 2 Bright field TEM images showing overview of specimen

Lattice fringe images and corresponding FFT (inserts) taken a close in nucleus and b further away in sector

Acknowledgements

The authors acknowledge T. Suzuki and H. Matsushima at JEOL-Japan for the FIB sample preparation.


Julianne Schmidt

Hannes Devos

Nicole Hoffman

Maud Ranchet

Abiodun Emmanuel Akinwuntan

L Stephen Miller

Abiodun Emmanuel

Driving After Concussion: Is it Safe to Drive After Symptoms Resolve?

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Authors:

Julianne D. Schmidt, Phd, ATC; University of Georgia, Athens, GA Hannes Devos, PhD, DRS; Augusta University, Augusta, GA Nicole Hoffman, MS, ATC; University of Georgia, Athens, GA Maud Ranchet, PhD; Augusta University, Augusta, GA Abiodun E. Akinwuntan, PhD, MPH, MBA; University of Kansas Medical Center, Kansas City, KS L. Stephen Miller, PhD; University of Georgia, Athens, GA Objective: To compare simulated driving performance between concussed and control participants. Design: Cross-sectional. Setting: Laboratory. Participants: Fourteen concussed participants and 14 non-concussed age and driving experience matched controls with no neurological disorders, medications causing drowsiness, or heavy drugs/alcohol use (Age:20.3years, 95%CI:19.9,20.7).

Interventions (or Assessment of Risk Factors):

Participants completed a 7.6 minute, 20.5km driving simulation task containing curves, crosswalks, accidents, rural/urban areas, pedestrians, overtaking, and evasion. Concussed participants completed driving simulation within 48 hours of becoming asymptomatic (15.9 days post-concussion, 95%CI:10.7,21.0) and were deemed clinically recovered by a medical professional using a multifaceted concussion evaluation. Outcome measures: We compared total number of accidents, tickets, and lane excursions between groups. We also compared average velocity (km/hr), standard deviation of velocity, lateral lane position (m), and lateral lane position standard deviation throughout simulation subsections. One-way ANOVAs were used (α=0.05). Main Results: Concussed participants committed more frequent lane excursions compared to controls (concussed: 10.9, 95%CI:8.3,13.5; controls: 7.4, 95%CI:6.0,8.8; p=0.02). Concussed participants exhibited greater lateral lane position standard deviation compared to controls during the first (concussed: 1.1m, 95%CI: 0.8,1.5; controls:0.7m, 95%CI:0.6, 0.9; p=0.02) and final curve (concussed: 1.2m, 95%CI:1.1,1.3; controls: 1.0m, 95%CI:0.9,1.1; p=0.04). Conclusions: Despite being considered clinically recovered, concussed participants were less able to center the vehicle in the lane and entered the shoulder more frequently, especially when navigating curves. A concussion may impair visual, motor, and/or cognitive skills necessary to safely drive. Further research is needed to determine when it is safe to return to driving following concussion.


Establishing a framework for driving rehabilitation in multiple sclerosis

Hannes Devos, Maud Ranchet, Deborah Backus, Abiodun Emmanuel

Akinwuntan

To cite this version:

Establishing a Framework for Driving Rehabilitation in Multiple Sclerosis

Hannes Devos, PhD, 1 Maud Ranchet, PhD, 1 Deborah Backus, PT, PhD, 2 Abiodun E. Akinwuntan, PhD, MPH, MBA 1,4 Objective: To establish a framework for driving rehabilitation by identifying the critical cognitive, visual, and motor deficits leading to impaired on-road driving in multiple sclerosis (MS).

Design: Prospective study.

Setting: Shepherd MS Center in Atlanta and Augusta University Simulator Lab

Participants: A total of 102 active drivers with MS who underwent detailed cognitive, motor, and visual testing as well as an on-road test.

Interventions: Not applicable

Main Outcomes Measures. Performance on off-road cognitive, visual, and motor tests was correlated with performance on 13 specific on-road driving skills. These driving skills were mapped onto an existing theoretic model of operational, tactical, visuo-integrative, and mixed driving clusters. Stepwise regression analysis was employed to determine the off-road impairments influencing performance on the on-road test and each cluster.

Results. Visuospatial function, inhibition, binocular acuity, vertical visual field, and stereopsis explained 37% (R 2 =0.37) of the variance in total on-road scores. Attentional shift, stereopsis, glare recovery, and use of assistive devices best predicted the operational cluster (R 2 =0.28). Visuospatial function, inhibition, reasoning, binocular acuity, and stereopsis best determined the tactical cluster (R 2 =0.41). The visuo-integrative model comprised binocular acuity and stereopsis (R 2 =0.12).

Inhibition and binocular acuity provided the best model to predict performance in the mixed cluster (R 2 =0.25). , 2016, -10-30, 97, 10, 1 p., DOI: 10.1016, /j.apmr.2016.08.009 .08.009

Conclusions and relevance

.

  Driving rehabilitation for individuals with MS should include remedial training of visuospatial and executive functions as well as compensatory strategies to correct for impaired visual acuity and field of view. Different training programs can be developed to target specific on-road driving skills.DEVOS, Hannes, RANCHET, Maud, BACKUS, Deborah, AKINWUNTAN, Abiodun Emmanuel, 2016, Establishing a framework for driving rehabilitation in multiple sclerosis, Archives of Physical Medecine and Rehabilitation, 2016 American Congress of Rehabilitation Medicine, CHICAGO, ETATS-UNIS