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Prospective appears at the beginning of the 20th century, as a result of the Great Depression which shook the United States, when the forecasting methods used until then were put into question [START_REF] Didier | En quoi consiste l'Ame ´rique? Les statistiques, le New Deal et la De ´mocratie[END_REF]. After the end of the Second World War, it developed in two centers, the United States and France, that devised anticipation methods with specific orientations for each of them. On the American side, the Rand Corporation was created, as a laboratory of prospective methods-like the Delphi method, for example-focused on technological forecasting approaches mostly conducted in a military context. On the French side, the necessity to move from a still rural economy to an economy that would be at the same time industrial and more competitive coincides with the appearance of a prospective attitude which takes a fresh look at forecasting methods and at the end goal. So, in the mid-1950s, the philosopher, Gaston Berger, initiated a new reflection on how to anticipate the future and on the methods used for making decisions and set up the Centre d'Etudes Prospectives. He contrasted a vision of the future freed from fatalism and the dependence on the past with the determinism stemmed from the positivist vision. "Tomorrow will not be like yesterday. It will be new and will depend on us" [START_REF] Berger | Sciences humaines et pre ´vision[END_REF](Berger, , 1958(Berger, , 1967)). The purpose of prospective is to prepare decisions and actions taking into account both changes in society and the potential impact of decisions on its development and, furthermore, in adopting a global approach to complex phenomena. Berger's pioneering work was continued on through the 1960s and 1970s by Bertrand de Jouvenel, the founder of the Futuribles Group (Association Internationale de Futuribles) which introduced the use of scenarios to construct positive images of the future or "scientific utopias" [START_REF] De Jouvenel | The Art of Conjecture[END_REF]. Since the 1970s, the work of the French pioneers has been expanded on by [START_REF] Godet | The Crisis in Forecasting and the Emergence of the Prospective Approach: With Case Studies in Energy and Air Transport[END_REF].

The translation of the French word prospective is still a matter of debate, sometimes translated by Futures Studies, forecasting, foresight. More than a translation problem, this reveals the existence of different conceptions between the two sides of the Atlantic. As an example, Michel Godet explains in one of his books that the concept of prospective failed for a long time to find an appropriate translation. Forecasting is judged by Michel Godet as too influenced by economic modeling and technological forecasting [START_REF] Godet | Creating Futures: Scenario Planning as a Strategic Management Tool[END_REF]. It was in 1996 that the relationship was established between prospective and foresight in an article about him: "The starting point of foresight, as with la prospective in France, is the belief that there are many possible futures" [START_REF] Martin | Technology Foresight: capturing the benefits from science-related technologies[END_REF][START_REF] Martin | The origins of the concept of foresight in science and technology: an insider's perspective[END_REF]. However, the correspondence is not perfect, because Foresight expresses the image of a given future whereas prospective designates at the same time a process, the result of this process and the preparation of a plan of action for powering the change wished for. Because of this voluntarist and strategic dimension of prospective, which is one of the specificities of the French viewpoint as compared to the American approach, Michel Godet recommends the use of the expression strategic foresight or strategic scenario building [START_REF] Godet | Creating Futures: Scenario Planning as a Strategic Management Tool[END_REF].

Prospective and temporalities

The specificity of the prospective approach stems from the way time-past, present, future-is taken into account in anticipating possible futures. Very often, the vision of the future is formatted by the past and kept in check by the tyranny of short-termism. Gaston Berger wrote in 1957: "Our civilization is breaking away from the fascination of the past with difficulty. Of the future, it only dreams and, when it works out projects that are no longer mere dreams, it draws them on a canvas on which it is still the past that is cast. It is stubbornly retrospective. It should become prospective" [START_REF] Berger | Sciences humaines et pre ´vision[END_REF]. Prospective seeks to inform society on the issues that both individuals and territories will have to confront in a distant future. This concern about long-term phenomena echoes the one which, at the beginning of the 1970s, underpinned the work of the Club of Rome and the publication of The Limits to Growth, first emblematic example of global and systemic prospectives conducted on a global scale [START_REF] Meadows | The Limits to Growth[END_REF].

Prospective intends to distinguish itself from extrapolation by the ambition to explore the future without extending the present. Nevertheless, the representation of possible futures is dependent on the importance given to the facts of the present. Conceptually speaking, the dynamics of the future come from the forces of change and forces of inertia which put a brake on evolutions. Then, it is important to identify them and to spot, among present events, future-oriented facts, weak signals, and bifurcation points. To do so, there is no universal technique, the prospective interpretation of the lessons of the past and facts of the present remains an art.

Scenarios, collective thinking, and debating: the foundations of prospective

Prospective is a discipline made up of various branches-territorial prospective, strategic prospective, and environmental prospective-developed from a common conceptual base. These branches share the common aim to make stakeholders aware of the implicit hypotheses on which their action is based and rest on the principle of freedom of action which enables individuals to have a hold on their future. Whatever the field of study, prospective consists in seeing far and wide in order to assess the consequences of decisions, carrying out an in-depth analysis so as to go beyond analogy and extrapolation, and anticipating potential breaks. On the other hand, it broadens the representations of the future to qualitative approaches and data that are not solely quantified. For example, it gives a dominant place to the points of view of stakeholders in the future. Scenarios, collective thinking, and debate are the mainstays of the prospective approach. Exploring the future consists in working out a range of future visions, which have to be sufficiently varied to apprehend the possible evolutions of the system being studied, sufficiently contrasted to be discussed, and also pertinent, and to help in decision-making.

Such exploration is carried out by building scenarios, an essential step in the prospective approach. These were introduced in the United States in the 1960s by Herman Kahn when he was working with the RAND Corporation, then at the Hudson Institute. Kahn defines the scenario as "a hypothetical succession of evens built with a view to highlighting causal sequences and decision nodes" [START_REF] Kahn | The Year 2000. A Framework for Speculation on the Next Thirty-Three Years[END_REF]. At the same time, in France, an interdepartmental government organization known as DATAR (the Office for Regional Planning and Development) launched the first prospective exercise on the image of France in the year 2000.

Nowadays, the term scenario encompasses different conceptions as well as a variety of methods and practices: the "experts" narrative of possible futures-probable, imaginable, plausible-, the systemic analysis, the quantitative or qualitative prospective model casting into the future a set of interrelated data and describing the future reality of the territory in an abstract manner. A scenario can be the reproduction of a scenario drawn up in a similar context and considered as being of interest for the situation in question. The aim of scenarios integrated into the prospective approach is to describe the future according to different options: a trend hypothesis-business as usual-vs hypotheses intentionally contrasted, introducing from the onset, or along the way, one or several "breaks"; forecasting vs backcasting approaches; building a general model vs variations of the benchmark model. There are three main schools of scenario building [START_REF] Houet | Usages des mode `les spatiaux pour la prospective[END_REF][START_REF] Amer | A review of scenario planning[END_REF][START_REF] Bradfield | The origins and evolution of scenario techniques in long range business planning[END_REF]):

• The "intuitive logics" consists in drawing up, in group, plausible narratives of causal chains without resorting to mathematical algorithms [START_REF] Wack | Scenarios: uncharted waters ahead[END_REF][START_REF] Huss | A move toward scenario analysis[END_REF][START_REF] Wright | Does the intuitive logics method-and its recent enhancementsproduce effective scenarios?[END_REF][START_REF] Derbyshire | Augmenting the intuitive logics scenario planning method for a more comprehensive analysis of causation[END_REF]). • The "probabilistic modified trends" made up of two different methods. The first-the trends-impact analysis-forecasts future trends based on past trends and introduces unprecedented events likely to bring about deviations from the extrapolated trend. The second-the cross-impact analysis-adds a higher complexity level with the analysis of the interdependence of events taken by two, depending on whether they have already occurred or not, in order to correct initial probabilities given by experts [START_REF] Bradfield | The origins and evolution of scenario techniques in long range business planning[END_REF][START_REF] Bishop | The current state of scenario development: an overview of techniques[END_REF]). • The "prospective school" [START_REF] Godet | Introduction to la prospective: seven keys ideas and one scenario method[END_REF] differentiates itself from the two previous families by a more elaborate approach, mechanist, and less intuitive. The construction of scenarios relies heavily on computerized mathematical models. The number of steps in the methodological method varies depending on the authors [START_REF] Durand | A new method for constructing scenarios[END_REF][START_REF] Godet | Introduction to la prospective: seven keys ideas and one scenario method[END_REF][START_REF] Schwartz | The Art of the Long View: Planning for the Future in an Uncertain World[END_REF][START_REF] Schoemaeker | Multiple Scenario development: its conceptual and behavioral foundation[END_REF][START_REF] Mermet | Pour une recherche prospective en environnement-repe `res the ´oriques et me ´thodologiques[END_REF].

Whatever the method, the collective thinking process is always integrated into the prospective approach, but in variable forms, and is more or less present in the various stages of the approach. It is indispensable for identifying the key variables of the dynamic of the system being studied, for analyzing the stakeholders' strategies and, in synthesis, for bringing forward major issues for the future. It is as much useful in the subsequent stages, to move from problems to prospects, then from prospects to processes. True, the future will never match a given scenario exactly, but the latter provides a working basis, a contribution to the ongoing debate in a prospective forum [START_REF] Mermet | E ´tudier des e ´cologies futures: un chantier ouvert pour les recherches prospectives environnementales[END_REF].

Since the 1990s, there have been an increasing number of studies and references on scenario methods in the scientific literature, as well as a proliferation of examples of scenarios in the public domain [START_REF] Martelli | Scenario building and scenario planning: state of the art and prospects of evolution[END_REF]. The scenario method is now widespread because it is seen as an effective dialogue tool between the various players involved in the implementation of a policy (Leve ˆque and Urien, 2005).

1.1.3 The fields of prospective: territorial prospective and environmental prospective

1.1.3.1 Territorial prospective
The aim of territorial prospective is to work out visions, prospects, and orientations concerning the evolution of a territory and its inhabitants so as to provide information and help to take a stance and strategic options in the most complex cases [START_REF] Loinger | Prospective et planification territoriales: Etat des lieux et propositions[END_REF]. Planning should not be mistaken for the territorial prospective exercise. Guy Loinger points out that planning consists in putting into perspective a set of development projects, sectorial programs, policies, etc., based on predictive analyses. Whereas planning does not take into account the opinion of stakeholders and the social acceptability of the planned future, in the case of territorial prospective, "it is a question of collectively building a vision of the future with other working methods and starting from broader and more 'questioning' representations of the past and the present" [START_REF] Loinger | Prospective et planification territoriales: Etat des lieux et propositions[END_REF]. There are different movements of territorial prospective that are classified in three main families: "cognitive prospective," which questions the future based on assessments, situation evaluations, diagnoses, and surveys; "participative prospective" in which the future is worked out with the participation of stakeholders; "strategic prospective," which sets a set of goals to reach within a certain time limit, and a plan of action to succeed in reaching them.

In France, prospective is almost exclusively associated with public policy and planning. The "French-style" prospective conducted by DATAR from 1963 to 2014 goes together with the production of scenarios illustrating cartographically the voluntarist development promoted by the State [START_REF] Delamarre | La prospective territoriale. La Documentation Franc ¸aise[END_REF]. We will mention among these, the "scenario of the unacceptable"-an image of France in the years 2020 to be proscribed-, a contrario, the "network polycentrism"-scenario desired for France in 2020-, and finally, all 28 scenarios on spatial systems in France, Europe, and the world, drawn up within the framework of "Territoires 2040," DATAR's latest prospective exercise [START_REF] Cordobes | Les plis de territoire 2040[END_REF].

From now on, the territories of EU member countries, from city to region, handle prospective themselves, anticipate evolutions, and define their own strategy (Van Cutsem and Roe ¨ls, 2012). Indeed, an abundance of strategic prospective exercises has been observed, conducted at both the local and regional levels, and generally underpinned by scientific research work.

For example, since 2007, the ESPON program, financed by the EU Structural Funds, has been carrying out scientific studies on regional development which are intended for providing the knowledge needed for the first stage of any territorial prospective study. The European Environment Agency also carries out prospective studies. An illustration of this is the PRELUDE project, which explores plausible long-term evolutions for land use and their environmental impact (EEA, 2007). It is modeled using contrasting scenarios combining information relating to five areas of intervention and action which are determining in the trajectories of land use change: protection of the environment, solidarity and equity, governance and public intervention, optimization of agriculture, technology, and innovation.

Modeling is carried out by applying a grid with cells of 18 km a side on the European area.

The results of simulations are presented in cartographic form. This project illustrates the current will to combine environmental and anthropic data in a fine-scale territorial prospective.

Environmental prospective

In response to the consequences, most often harmful (pollution, destruction of environments and species, exploitation of nonrenewable resources, soil erosion, etc.) of anthropic action on natural environments, biodiversity, health, and the economy, the scientific community and territorial decision-makers have become involved in studying the future of the environment with the aim of slowing down, stopping the degradation of the ecosystems, or even improving the quality of the natural habitats and our environment. Some of the concrete actions that have been deployed internationally include UNESCO's Man And Biosphere (MAB) program, which was established by UNESCO (United Nations Educational, Scientific and Cultural Organization) in 1971 and aimed at the time to reconcile the human with its environment.

In parallel with the MAB program, Donella and Dennis Meadows, with Jorgen Randers and William W. Behrens III, published in 1972, on behalf of the Club of Rome, the book entitled "The Limits to Growth." Based on an approach based on the work of Jay W.

Forrester in the early 1960s on systems dynamics, this global foresight work presented different scenarios of global evolution of natural resources and population. Although not based on a spatially explicit approach, the different results of simulations of evolution by 2100 were particularly worrying: they showed a significant decrease in natural resources and an equally significant increase in pollution and atmospheric CO 2 concentration. The consequences of the world demography were to be a major reduction of the population toward the end of the 21st century. This foresight work has had the merit of raising public awareness, politicians, and industry on the risks generated by economic development that does not take into account the limits of natural resources. Moreover, the comparison between the values simulated in 1972 and those currently observed are quite similar for variables such as the average atmospheric CO 2 content, the birth rate, the world population, and the reduction of arable land, for example. The two updates of these models published in 1992 and 2004 clarified and confirmed the evolutionary trends initially presented. This work stimulated a group of researchers who, in the following years, began researching the evolution of ecosystems, ecosystem services, and society. The accumulation of work highlighting the risks for mankind of an economy based on ever more consumptionconsuming growth of exhaustible resources and increasingly polluting led the United Nations, in 1987, to define the concept of "Sustainable development" in the famous Brundtland report. The World Commission on Environment and Development was asked by the UN General Assembly to decide on the establishment of a timetable to promote a change based on sustainable development by the year 2000 and beyond. Indeed, this commission had pointed out that the ecological imbalances observed over the last decades had accentuated the disparities between human populations, accentuating poverty, health, and food problems. Because of the idea of sustainability, the concept of sustainable development then means looking ahead. But how?

In 1988 the United Nations Environment Programme of the UNO and the WMO (World Meteorological Organization) established the Intergovernmental Panel on Climate Change (IPCC). The main objectives of the IPCC are to study the evolution of climate and its impacts on ecosystems and society and to propose strategies in order to prevent risks due to global warming. The first assessment report was published in 1990 and the last and fifth in 2014. IPCC gathers more than 800 scientists that expertized more than 9000 publications about climate change evidences, its evolution, the current and potential consequences on ecosystems and society, and the options to mitigate the climate change and its expected consequences on the territories. Due to the very large literature review, very different approaches contribute to design the scenarios of climate evolution and its potential impacts on many aspects of our society. Some of these studies are spatially explicit but they do not always integrate the stakeholders demand or issues in the definition of the problematics and/or in the perspective of use of the results for the society. Most of the works analyzed by the IPCC concerning adaptation planning are based on expert opinions and some multicriteria optimization approaches that integrate climate change scenarios.

In We can conclude that, in environmental prospective, most of the researches are based on methodologies combining expert knowledge and modeling techniques of land use, integrating the evolution of climate change. Most of them are not spatially explicit and when they are, it is not clear if they take into account the issues raised by the stakeholders.

Stage 2 of prospective: taking into account geographic and sociospatial differentiations

In the last 20 years or so, scientific work carried out in environmental sciences and research work initiated on sustainable development in the field of social sciences-economy, geography, sociology, political science-led to delving into a number of subjects, including multilevel relationship, and existing differentiations across space. Such questioning had the effect of bringing changes to prospective approaches.

Spatial differentiations and multilevel interactions

Within the framework of studies carried out by the IPCC, the global atmospheric models used are applied on the lower levels using downscaling methods (IPCC, 2007). However, despite the steady improvement of the models used, climate information resulting from forecasts is still too approximate at the local level to meet the requirements of impact studies and adaptation measures. The climate's spatial variability has long been demonstrated by geographers [START_REF] Yoshimo | Climate in a Small Area: An Introduction to Local Meteorology[END_REF][START_REF] Oke | Boundary Layer Climates[END_REF][START_REF] Beltrando | Les ge ´ographes-climatologues franc ¸ais et le changement climatique aux e ´chelles re ´gionales[END_REF][START_REF] Bonnardot | Using atmospheric and statistical models to understand local climate and assess spatial temperature variability at fine scale over the Stellenbosch wine district, South Africa[END_REF][START_REF] Quenol | Climate analysis at local scale in the context of climate change[END_REF]. Due to topography and land use, local temperature variations can be equal or higher than the temperature rises simulated by IPCC scenarios. Taking into account this multiscale spatial variability in scenarios, and broadly speaking, the functioning of local-scale geosystems has now become a challenge for the scientific community and is still to this day one of the stumbling blocks of prospective climate modeling.

Furthermore, giving further thought to sustainable development and to the necessary adaptation to global changes brings about the notion of systemic complexity of which the multilevel interactions are one of the dimensions [START_REF] Allen | Hierarchy: Perspectives for Ecological Complexity[END_REF][START_REF] Wu | Hierarchy and scaling: extrapolating information along a scaling ladder[END_REF]. As stressed by the French biophysicist and philosopher Henri Atlan, such complexity lies in the fact that an observer lacks information to account for the global significance of local phenomena, taking into account the information that the observer can acquire on these two levels [START_REF] Atlan | Entre le cristal et la fume ´e[END_REF]. The economist, Olivier Godard, in an incisive article published in 1996 in the journal Futuribles, draws attention to the error consisting in believing that sustainable development implies adopting the same approach at the various territorial scales-global, continental, national, and local [START_REF] Godard | Le de ´veloppement durable et le devenir des villes: bonnes intentions et fausses bonnes ide ´es[END_REF]. He enjoins researchers and prospectivists "not to mechanically transfer reasonings from one scale to another," arguing that ecological constraint has an absolute meaning only at the global level; at all other levels, exchanges, substitutions, and imbalances can occur. Thus ecological constraints are relative; in that sense, sustainable development is not fractal. Likewise, he makes the case that sustainability is nonadditive. Depending on the territorial scales considered, recommendations and priorities will not be the same [START_REF] Godard | Autonomie socio-e ´conomique et externalisation de l'environnement: la the ´orie ne ´o-classique mise en perspective[END_REF][START_REF] Godard | Le de ´veloppement durable et le devenir des villes: bonnes intentions et fausses bonnes ide ´es[END_REF].

Challenging generic models

The challenging of "universal" models applicable to all scales, from global to local, appears in a number of studies, and more particularly as regards the environmental prospective rooted in simple causality and biophysical determinisms [START_REF] Fernandez | Reconside ´rer la prospective de l'eau en Europe dans ses dimensions politiques[END_REF]. Questions are raised on the normative content of the hypotheses used for defining cause-and-effect relationships, and on the physical limits of the system being studied. The critical analysis conducted on the DPSIR (Driving forces-Pressures-State-Impacts-Responses) model is a perfect example of the foregoing. This model belongs to the family of analysis tools aimed at producing useful information for decision-making, in the context of public policies. In this perspective, they are designed with a view to reducing complexity via a chain of causal links, in order to measure, with easily understandable indicators, the state of a phenomenon, and to identify and monitor the pressures affecting it. Using the DPSIR model is strongly encouraged by the European Environment Agency as well as by the Organization for Economic Cooperation and Development (OECD) and the FAO (United Nations Food and Agriculture Organization). Now, work carried out in social sciences and based on its use in water prospective in Europe gave rise to reservations on using it without prior consideration of the territory being studied. The criticisms stress that the Driving Forces are "anonymous" and "a-temporal" and that neither the stakeholders nor the trajectory of the territory on which the model is built is taken into account; the perimeter of the model is solely centered on physical or biophysical elements-for example, watershed-yet, sociosystems are part of particular geographies which transcend physical limits [START_REF] Fernandez | Reconside ´rer la prospective de l'eau en Europe dans ses dimensions politiques[END_REF]. Then, the authors advise to apply the DPSIR model from various angles: resources, policies, main players, with variable scales. The advantage of these variations is, on the one hand, to better grasp the complexity of spatialized problems, "what is seen as passive in a scenario can become the level of response in another"; on the other hand, to build more relevant contrasted prospective scenarios, by taking into account differentiated operating logics depending on the nature and extent of the territorial context: Europe, administrative region, portion of river basin, etc. [START_REF] Fernandez | Reconside ´rer la prospective de l'eau en Europe dans ses dimensions politiques[END_REF].

These criticisms of the normative models with a universal scope echo the analysis carried out in parallel on their use in public policies, and more precisely on the EU water framework directive [START_REF] Kallis | Evolution of EU water policy: a critical assessment and a hopeful perspective[END_REF]. [START_REF] Ward | Implementing European water quality directives: lessons for sustainable development[END_REF] examined critically the European Union's environmental policy. They stressed that the environmental regulation at the high European level often does not account adequately for the variety of problematic situations experienced in the Member States, for example, between urban northern areas and rural southern ones.

Combining generic and local prospective scenarios

It is, notably, to avoid this pitfall that new approaches of multiscale and participative prospective modeling have come up within the framework of European research programs.

The PLUREL project will be taken as an example. The PLUREL project was designed between 2007 and 2010, in the context of the sixth framework program for research and technological development; its aim is to define the possible trajectories of European territorial units by 2025. Its originality lies in the combination of two interlocked series of multiscale modeling. The first consists of four contrasted scenarios, adapted from IPCC's baseline scenarios in 2000. The second applies these four scenarios at the level of the urban areas of six European metropoles varying in size, territorial organization, and spatial planning of urban development. In all six towns, people involved in local governance were requested to transcribe, in experts' words, the principles of the four prospective scenarios in the development dynamics of their respective territories, including local constraints and the urban planning legislations specific to each European state. Simulations are carried out on the Ispra Joint Research Center's Moland modeling and simulation platform. The results of the simulations reflect the combination of processes applied both at the European scale and that of the urban area being studied, and are mapped at that scale [START_REF] Chery | Les espaces pe ´riurbains en Europe: un grand e ´cart entre description et prospective[END_REF][START_REF] Chery | Sce ´narios prospectifs et mode ´lisation des changements d'utilisation des sols: les dynamiques de pe ´riurbanisation dans la re ´gion de Montpellier a `l'horizon 2025. 48e `me colloque de l[END_REF].

From spatial change to spatial prospective

Geographers went late into anticipating the future; they rather tended to direct their research toward the organization of space, observing spatial differentiations, assessing the lines of force of French space in the European context [START_REF] Eckert | Evaluation et prospective des territoires. Reclus Montpellier. La Documentation franc ¸aise[END_REF][START_REF] Brunet | Evaluation et prospective des territoires[END_REF]. In 1998 Denise Pumain even wondered whether geography would be able to invent the future [START_REF] Pumain | La ge ´ographie saurait-elle inventer le futur[END_REF]. Since then, the challenge was taken up by geographers, most of them belonging to the theoretical and quantitative geography movement. Their research work first led them to study processes generating spatial change, then to explore the issue of anticipating change.

At the beginning of the year 2000, spatial change was addressed from a theoretical and conceptual point of view by the geographers of the EPEES (Espaces Post-Euclidiens et Eve ´nements Spatiaux) group, who devised the concept of spatial event [START_REF] Epees | Eve ´nement spatial[END_REF]. Their thoughts focused on the transformation process of spatial systems. The selforganization theories that formalize system dynamics from their components' multiple interactions provide a key to understanding the relationship observed between temporal rhythms and changes in space. As an example, the apparent opposition between fast and numerous spatial changes and the near-stationary organization of space becomes understandable in the light of self-organization mathematical models which describe how the dynamics of a system reconciles micro, fast, and seemingly random fluctuations, and a slow dynamics at the macro level. These researchers also looked into the context which makes that an event triggers a process which will produce a new spatial repartition with different consequences for the same event, depending on the place where it happens, and also into the "unexpected" effects occurring in some places.

Studies carried out on spatial change led geographers to take a critical look at prospective. They questioned the fact that spatial dynamics were ignored. How can people write scenarios of the future evolution of a space without knowing its spatiotemporal trajectory? [START_REF] Lajoie | Mode ´lisation et prospective territoriale[END_REF]. Prospective cannot ignore that environmental and anthropic phenomena to come will affect space in a differentiated manner. Moreover, they questioned the notions of stake and stake-laden space referred to in prospective diagnoses. Public policy apprehends the evolution of a place in terms of stakes generally linked to social or environmental risk as well as the expectations of both the society and the authorities. A stake-laden space is then seen as a lever for action. Now, stake-laden spaces are often declared such in terms of priorities rather than as a result of analyses truly devoted to detecting them. The stake-laden spaces identified by geographers can be completely different, even in contradiction with those chosen by public policies. For Voiron-Canicio ( 2013), a stake-laden space is defined by three precise situations: either a space-area or place-where tensions crystallize, whether they be latent or expressed by permanent or episodic conflicts; or a space with a vital interest due to some remarkable elements-populations or resources, such evaluation being assessed in terms of the prejudice that would be caused if they disappeared, and the benefit resulting from keeping them or reintroducing them; or else a space of strategic interest, not for a category of players in particular, but for the functioning of a territory or the sociosystem considered, because of the strong probability of its transformation impacting the rest of the system. The stake-laden space thus defined puts into question the notion of general interest as it is usually regarded by public policies, that is, assessed in respect of the estimated needs of individuals rather than those of the land, considering the place in a functional manner, on an area defined at an administrative level, focusing on the short term rather than on the long term (Voiron-Canicio and Olivier, 2005a,b;[START_REF] Voiron-Canicio | Anticiper et simuler les dynamiques de changement pour diagnostiquer et ame ´liorer la re ´silience d'un syste `me territorial urbain. Risques urbains[END_REF][START_REF] Voiron-Canicio | De ´celer les espaces a `enjeux pour l'ame ´nagement[END_REF][START_REF] Dutozia | Espaces a `enjeux et effets de re ´seaux dans les syste `mes de risques[END_REF][START_REF] Liziard | Littoralisation de la fac ¸ade nord-me ´diterrane ´enne: Analyse spatiale et prospective dans le contexte du changement climatique, The `se de ge ´ographie[END_REF].

All these geographical studies are based on the same premise: space is considered as both organized and organizing. Spatial systems carry a spatial heritage which exerts constraints on projects, decisions, and a society's behavior, but which is also a potential that agents reexamine and reassess constantly, depending on their needs and aspirations, in regard to the dynamics and potentialities of other territories [START_REF] Voiron-Canicio | L'espace dans la mode ´lisation des interactions nature-socie ´te[END_REF].

The spatial prospective devised by Ce ´cile Helle and Laure Casanova falls within this framework. It extends these works while directing them toward the measurement of the sensitivity of spaces faced with change, in a perspective of aid to decision-making [START_REF] Casanova | Les dynamiques du foncier a `ba ˆtir comme marqueurs du devenir des territoires de Provence inte ´rieure, littorale et pre ´alpine: e ´le ´ments de prospective spatiale pour l'action territoriale, the `se[END_REF][START_REF] Casanova | Ce que les dynamiques foncie `res re ´ve `lent du devenir des territoires: e ´le ´ments de prospective du sud-est franc ¸ais[END_REF]. Attention is drawn to the preparation of spatial changes and the possibility to intervene on the evolution trajectory of a space, depending on the leeway available. For these authors, the purpose of spatial prospective is to "envisage the ways in which space can change and the incidences of such change, to better prepare it and be prepared to it, which amounts to questioning the modalities of a space's future differentiation" [START_REF] Casanova | Les dynamiques du foncier a `ba ˆtir comme marqueurs du devenir des territoires de Provence inte ´rieure, littorale et pre ´alpine: e ´le ´ments de prospective spatiale pour l'action territoriale, the `se[END_REF]. The mechanisms and factors of evolution of territorial systems are revealed by a diagnosis combining the spatial, temporal, functional, and perceptive dimensions.

Spatial prospective consists in studying the possibilities for the transformation of spaces, starting from the premise that some logics of evolution are more favorable to change than others. The approach is carried out in two phases: identifying the stage of evolution of the territories and identifying the "possibles" of territorial action. The first phase studies the territory's potentiality in connection with its specific qualities, its resources-those exploited and those latent, in reserve. Qualifying this potentiality "should enable one to apprehend the capability of a territorial system to continue as it is or to become another system likely to meet the requirements of (present and future) societies" [START_REF] Casanova | Les dynamiques du foncier a `ba ˆtir comme marqueurs du devenir des territoires de Provence inte ´rieure, littorale et pre ´alpine: e ´le ´ments de prospective spatiale pour l'action territoriale, the `se[END_REF].

In the second phase, the "possibles" of territorial action ensue, on the one hand, from the territory's sensitivity to change, that is, from the differentiated behavior of spaces faced with the same event as a result both of their specific qualities and their stage of development; and on the other hand, from the territory's degree of freedom, that is, from the part of constraint linked to the existing spatial organization, which is likely to influence the territory's future evolution. It is necessary to evaluate the degree of freedom in order to assess the leeway as regards development. The operational aim of spatial prospective for future actions of development lies in detecting both the moments and environments most favorable for change [START_REF] Casanova | Les dynamiques du foncier a `ba ˆtir comme marqueurs du devenir des territoires de Provence inte ´rieure, littorale et pre ´alpine: e ´le ´ments de prospective spatiale pour l'action territoriale, the `se[END_REF].

These considerations and research in spatial analysis have opened up a new field of exploration of the spatial future. They generated a prospective approach the specificity of which is based on the importance given to the spatial dimension, and to the attention paid to spatiotemporal factors in anticipating changes.

The emergence of geoprospective

In the mid-2000s, several research movements converged on the issue of anticipating the evolution of spatial systems, by using a number of common or similar principles, methods, and operating modes, without referring to the term geoprospective in all the cases. And when the term was used, the prefix geo covered different contents according to the areas of application.

The first mentions of geoprospective

As far as we know, the term "geoprospective" was first introduced by the Bureau of Geological and Mining Resources (BRGM) in France, at the beginning of the 1980s, without being defined with precision, within the scientific and technical frameworks of studying the evolution of the geophysical properties of radioactive waste storage sites in order to ensure their containment [START_REF] Gadalia | Etude ge ´oprospective d'un site de stockage. L'activite ´volcanique[END_REF]. The aspect linked to assessing risks, in particular those eventually leading to the loss of containment of the radioactive waste storage site's geological structure, was already there at the origin of geoprospective. It was only in the mid-1990s that the term was defined more precisely: "The geoprospective approach aims to work out plausible and coherent scenarios of this natural evolution and to assess its consequences in order to draw profitable lessons in terms of the capacity of a site to accommodate a project, and even of devising the project itself. It thus contributes to scientific objectives (demonstrating the project's feasibility), also technological and operational (project optimization) and to decision-making (selection of sites, project acceptability)" [START_REF] Godefroy | Evolution des concepts, me ´thodes et outils de la ge ´oprospective[END_REF]. The term was used with this meaning in the works of the BRGM throughout the years 1980 and 1990 [START_REF] Courbouleix | Etude ge ´oprospective d'un site de stockage. Climatologie: e ´volution du climat et glaciations[END_REF][START_REF] Godefroy | Etude ge ´oprospective d'un site de stockage. La prise en compte de l'activite ´sismique[END_REF][START_REF] Gros | Etude ge ´oprospective d'un site de stockage. Tectonique prospective: dure ´e des phases compressives et distensives re ´centes, e ´volution du champ de contraintes dans les 100 000 ans a `venir[END_REF][START_REF] Canceill | Etude geoprospective d'un site de stockage: Simulation de l'evolution d'un site a l'aide du programme "Castor[END_REF][START_REF] Afzali | Ge ´oprospective: de ´veloppement de la mode ´lisation. Evaluation des vitesses d'alte ´ration et d'e ´rosion dans divers contextes[END_REF][START_REF] Afzali | Ge ´oprospective: de ´veloppement de la mode ´lisation. E ´valuation des vitesses d'alte ´ration et d'e ´rosion dans divers contextes[END_REF][START_REF] Garcin | GEOPROSPECT TD (Time Dependant): De ´monstrateur d'atelier de ge ´oprospective[END_REF][START_REF] Godefroy | Evolution des concepts, me ´thodes et outils de la ge ´oprospective[END_REF] and until the mid-2000s [START_REF] Casanova | Projet PALEOHYD II. Pale ´ohydrologie et ge ´oprospective: mode `les conceptuels et processus d'acquisition de la chimie des eaux dans les massifs granitiques[END_REF], while resorting to modeling techniques and tools for simulating the physical evolution of storage sites. For this reason, at a symposium organized by the National Agency for the Management of Radioactive Waste (ANDRA), the BRGM and Paris Ecole des Mines [START_REF] Godefroy | Evolution des concepts, me ´thodes et outils de la ge ´oprospective[END_REF]we ntba ckonth e evolution of geoprospective methods with, notably, the move toward models integrating artificial intelligence techniques and expert advice for constructing realistic scenarios.

These studies thus laid the foundations for the research claiming to belong to geoprospective, that is, integrating "the spatial expression of phenomena the impact of which can be relativized in comparison with different project opinions..." [START_REF] Godefroy | Evolution des concepts, me ´thodes et outils de la ge ´oprospective[END_REF]. Taking the spatial dimension into account (in parallel with the temporal dimension) in geoprospective studies is therefore clearly assumed by the BRGM, while explaining the importance of the specific transposition of methods and tools to local circumstances. However, whereas research work concerning the storage of nuclear waste is still ongoing, the term seems to have fallen into disuse at the BRGM after 2004. In parallel, in 1998 Jean-Paul Ferrier published "Le contrat ge ´ographique ou l'habitation durable des territoires" (the geographic contract or sustainable housing in territories) in which the author introduces the term "geoprospective" in a more geographical context linked to considerations on sustainable development, without defining it precisely.

New geographical studies claiming to belong to geoprospective or spatialized prospective

It was only in the mid-2000s that geoprospective sparked renewed interest. Geoprospective is tied up with spatial modeling. The 2004 situation report of the CNRS' section 39 "Spaces, Territories and Societies" clarifies the scientific issues: "Existing expectations in geoprospective direct research towards the notions of unpredictability and emergence which are the main difficulties in that field. One of the stances taken by researchers consists in considering that emergences are not totally unpredictable. Analyzing and modeling spatial interaction help to grasp the complexity of dynamics, to simulate the geosystems' possible futures and to produce spatialized decision-making tools" (CNRS, 2004). The ESPACE laboratory, a joint research unit of CNRS, was a trailblazer by including geoprospective in its 2004À07 scientific program. Indeed, a line of research is devoted to working out a new kind of territorial diagnosis, more powerful than the standard diagnosis, aimed at searching, in the present, harbingers of change and emergence that could weigh heavily in the future organization of territorial systems and help in territory geoprospective.

Christine Voiron-Canicio, in her research on urban paralysis risks in times of disaster published in 2005, uses the term "geoprospective" to describe the approach combining spatial analysis, GIS, and spatial simulations, designed for anticipating the consequences of a crisis situation and help the town of Nice to become better prepared (Voiron-Canicio and Olivier, 2005a,b). In 2006, she defined the scope of geoprospective more precisely: "Its purpose, as in the case of territorial prospective, is to get to know and foresee in order to organize and decide, but its specificity is to anticipate the evolution of a territory by understanding its spatial dynamics and to spatialize, on the medium and large scale, the evolution scenarios, development recommendations and their spatial impacts. Therefore geoprospective is inconceivable without spatial modeling" [START_REF] Voiron-Canicio | L'espace dans la mode ´lisation des interactions nature-socie ´te[END_REF]. In parallel, Thomas Houet, in the context of a research on environmental prospective, suggested a spatially explicit simulation method of prospective scenarios aimed at detecting the influence of measures for adapting to the reform of the European Union's Common Agricultural Policy [START_REF] Houet | Mode ´lisation prospective de l'occupation du sol en zone agricole intensive: evaluation par simulations dynamiques de l'impact de l'e ´volution des exploitations agricoles dans la France de l'Ouest[END_REF]. He described this approach as spatialized prospective.

In the years that followed, new research works claiming to be geoprospective or spatialized prospective were carried out. Moreover, a social demand appeared for the scientific community to work out, test, and validate methods enabling to spatially simulate phenomena, and to quantitatively evaluate the consequences of policy choices. In 2011, researchers from four CNRS laboratories-ESPACE, EVS, GEODE, and LETG-working in that field, together with the CNRS Me ´thodes et Applications pour la Ge ´omatique et l'Information Spatiale research group (GDR MAGIS), organized a seminar on the theme "Geoprospective: contribution of the spatial dimension to prospective research." That seminar brought together some 50 participants and provided the first opportunity for exchanging views and debating on the various conceptions of this new research field as well as on achievements based on the use of the spatial element in territorial and environmental prospective. As a follow-up of the seminar, a "geoprospective" group was created within the GDR MAGIS, and two surveys were devoted to geoprospective, one in an issue of the review, L'Espace ge ´ographique (EG 2012-2), and the other in the online review Cyberge ´o.

A construction at the interface of several fields of research

Geoprospective is mainly driven and disseminated within the scientific community by geographers belonging to the movement of "theoretical and quantitative geography" and spatial analysis. Spatialized modeling and simulation, which are their common denominator, take various forms and are most of the time hybridized with methods stemmed from other lines of research, such as Land Change, Land System, Companion Modeling, and, of course, the prospective research stream.

1.3.3.1 "Theoretical and quantitative geography" and spatial analysis

In the past, a number of French geographers have taken a critical look at prospective: "a highbrow and ambitious word supposed to give quality to guesswork about the future" [START_REF] Brunet | Les mots de la ge ´ographie, dictionnaire critique[END_REF], while stressing the necessity to scrutinize, within spatial systems, the retroactions and risks of breakage or bifurcation. These issues and, more broadly, the prospective questioning, concern theoretical and quantitative geography as well as spatial analysis. By confronting structures and dynamics, forms, and flows, and by exploring the processes of spatial change, the latter is eminently spatiotemporal. De facto, spatial dynamics are carriers of geoprospective; "Geoprospective seen as an attempt to integrate spatial differentiation into the prospective approach is an obvious field of application of spatial analysis" [START_REF] Charre | Programme scientifique 2004-2007 de l'UMR ESPACE[END_REF].

Since the last four decades, the theoretical and quantitative geography movement endeavors to define the processes that generate spatial dynamics. To do so, it relies on various theories-more particularly on self-organization theories-and also on modeling and simulation. Two kinds of tools are used, on the one hand, macrodynamic models based on nonlinear differential equations, and on the other hand, tools that consider space as a collection of particles-cellular automata, multiagent system-which they use for trying to formalize the change of scale. Nowadays, this field of research faces a dual challenge. On the one hand, a shift of perspective with regard to change, with the aim to explain it ex ante and no longer a posteriori only. "By allowing to achieve, not an accurate prediction, but the exploration of a diversity of possible futures, will these models help to study the change in geographical structures in a nomothetic way?" [START_REF] Pumain | La ge ´ographie saurait-elle inventer le futur[END_REF]. Furthermore, will they help in the prospective formulation, and even in decision-making. Indeed, there is a great demand for geoprospective-oriented spatial models that would be within the reach of the highest possible number of executives so as to help them simulate the spatial impacts of an envisaged measure and evaluate how development policies can reinforce or constrain territorial dynamics. The specificity of the contribution of spatial analysis to prospective lies both in these spatiotemporal questionings and in the methodological, theoretical, and applied corpus designed for attempting to find answers [START_REF] Voiron-Canicio | L'espace dans la mode ´lisation des interactions nature-socie ´te[END_REF].

Land change science

In the mid-1980s, two important programs concerning the transformations of ecosystems and land systems were launched: the Land Use and Land Cover Change Project (LUCC) in 1994 and its successor the Global Land Project in 2005. Both were interdisciplinary projects within the International Geosphere-Biosphere Program (IGBP) [START_REF] Lambin | Land-use and land-cover change (LUCC): implementation strategy[END_REF] bringing together researchers in landscape ecology, biogeography, political ecology, resource economics geographical information and remote sensing, etc., aiming to understand the land use/cover change dynamics and their relationship with global environmental change. A new line of research referred to as land change or land system science emerged from these works; its aim was to try to understand the land use/cover change dynamics by interlinking social systems and ecosystems [START_REF] Verburg | Land system science and sustainable development of the earth system: a global land project perspective[END_REF]. Research was carried out in four directions: observation and monitoring of land changes, understanding of these changes as a coupled humanÀenvironment system, spatially explicit modeling of land change, and assessments of system outcomes [START_REF] Gutman | Land Change Science: Observing, Monitoring, and Understanding Trajectories of Change on the Earth's Surface[END_REF][START_REF] Turner | The emergence of land change science for global environmental change and sustainability[END_REF]. The favored methodology is that of "Integrated Assessment of the land system" [START_REF] Kok | Integrated assessment of the land system: the future of land use[END_REF]. The main theme in the LUCC community is the modeling of land use dynamics and its social and environmental impacts. Scenarios is a second recurrent theme. Both models and scenarios can be developed by using participatory approaches [START_REF] Kok | Integrated assessment of the land system: the future of land use[END_REF]. Research work carried out in that context strongly contributed to the development of prospective modeling and spatial simulation on land cover/use changes on various scales [START_REF] Glp | Global Land Project. Science plan and implementation strategy[END_REF].

Spatialized participatory approaches

These approaches are characterized by the involvement of the stakeholders at every stage of the prospective process. The Companion Modeling approach is one of the best-known methods, and also the nearest to geoprospective. This approach appeared in 1996, then was developed and formalized by a community of researchers, the ComMod Network; it uses agent-based, GIS and role-playing game models as tools to help solve complex environmental issues involving several stakeholders. It consists in producing models shared by all to represent the functioning of the system being studied, helping in dialogue, and in fine, reach a solution accepted by all stakeholders [START_REF] Bousquet | Multi-agent simulations and ecosystem management: a review[END_REF].

The participatory territorial prospective works lie at the crossroads of participatory approaches and territorial prospective [START_REF] Piveteau | Prospective et territoire: apport d'une re ´flexion sur le jeu[END_REF][START_REF] Lardon | Developing a territorial project. The territory game, a coordination tool for local stakeholders[END_REF][START_REF] Lardon | Repre ´sentations spatiales dans les de ´marches participatives: production et usages[END_REF][START_REF] Lardon | Prospective participative pour la zone urbaine de Pise (Italie): l'eau et l'alimentation comme enjeux de de ´veloppement territorial[END_REF]. They use spatial representation on various media-maps, landscape block diagrams, graphic models-as a mediation tool to foster the participation of stakeholders and their involvement in the collective action. "Prospective-action" makes use of the knowledge of researchers and stakeholders, mediatized via a participatory device based on spatial representations [START_REF] Lardon | Repre ´sentations spatiales dans les de ´marches participatives: production et usages[END_REF] to produce both scientific knowledge and knowledge for action [START_REF] Lardon | Prospective participative pour la zone urbaine de Pise (Italie): l'eau et l'alimentation comme enjeux de de ´veloppement territorial[END_REF].

Nowadays, these lines of research hybridize geoprospective much more than prospective does, although the approach originated from the latter (Fig. 1

.1).

There is an imbalance between assessment prospective as a decision support, which is well represented on various scales, and academic prospective, both environmental and territorial, driven by a restricted circle of scientists. The reasons are various. The prevailing scientific posture is more focused on the analysis of past dynamics than on those of the future, which are more uncertain and controversial. Such uncertainty results in divergent analyses and difficulty validating affirmations concerning the conditions of the future. Eleonora Barbieri [START_REF] Barbieri Masini | La prospective et les tendances a `l'unite ´et a `l'adversite ´[END_REF] wrote on that subject: "the scientific nature of prospective is its most controversial characteristic, and in fact, for numerous researchers, it is not included in the qualities of prospective." Moreover, Laurent Mermet and Xavier Poux (2002) consider that the great majority of researchers involved in research work on the environment is in near total ignorance of theoretical questionings and methodological resources in works specialized in prospective.

Conclusion

Geoprospective is an emerging field of research driven by a reduced number of researchers, mostly French. Its singularity is due at the same time to its concept, its projects, and its practices. The concept is based on the central and essential place allocated to the spatial dimension in the medium-term and long-term anticipation processes of the evolution of the system being studied: ecosystem and territory.

As is the case with prospective, the target is to provide aid for action in public policy, planning, or management. However, the primary objective is of a scientific nature. The project of geoprospective is to consider, through research, the space being studied in its complexity, by trying to identify its structures and dynamics, and to understand the anthropic and environmental dynamics as well as their spatial interactions on different scales, and their impacts on the system being studied in the context of uncertainty about the future. This is a key issue, which falls within both fundamental and applied research. By associating theory and practice, the geoprospective posture tends to reduce the fundamental research/applied research dichotomy, which has become artificial in many respects in geography, but is still rooted in minds [START_REF] Charre | Programme scientifique 2004-2007 de l'UMR ESPACE[END_REF]. Geoprospective is not a school, it is a posture open to different lines of research, which encompasses various methods and practices that take part in its construction, none of them being exclusive. The formalization of the approach is built on a small number of principles and basic rules which were consensual in the founding works and were adopted de facto (Voiron-Canicio and Olivier, 2005a,b;[START_REF] Voiron-Canicio | L'espace dans la mode ´lisation des interactions nature-socie ´te[END_REF][START_REF] Houet | Mode ´lisation prospective de l'occupation du sol en zone agricole intensive: evaluation par simulations dynamiques de l'impact de l'e ´volution des exploitations agricoles dans la France de l'Ouest[END_REF][START_REF] Gourmelon | La ge ´oprospective, apport des approches spatiales a `la prospective[END_REF][START_REF] Houet | La ge ´oprospective-Apport de la dimension spatiale aux de ´marches prospectives[END_REF]:

• Taking into account the spatial dimension of the problem is the vital lead of the approach. The spatial reasoning underpins the various stages of the process of anticipating the future. • The prospective is carried out using spatialized representations of possible futures. The scenarios and models, whether quantitative or qualitative, aim to detect the spatial impacts of changes to come. • The end application of the knowledge resulting from the geoprospective approach is aid to action. • Geoprospective is a scientific approach. Spatial representations and models of the future cannot be validated by conventional methods, but nevertheless must meet the criteria of likelihood, pertinence, coherence, and usefulness.

Those researchers who choose to link their works to the field of geoprospective implicitly adhere to these rules, by inscribing their research in the wake of the founding works which they reference. Nevertheless, divergences exist over two points, the kind of modeling approach used and the inclusion of stakeholders in the course of the geoprospective approach. The choice of spatial modeling of the future varies according to the theme, the usual practices of the disciplines, and depending on the researcher's methodological background: quantitative model vs qualitative model, spatialized scenarios vs spatially explicit scenarios. The strongest discrepancies concern the place allocated to stakeholders in the development of the approach. The stakeholders' implication is strong in geoprospective approaches regarding territorial prospective, the integrated management of a resource or an area-littoral, mountain,.-, risk adaptation; it is more limited and still rather rare in the case of climate, hydrology, or biodiversity issues.

This unstabilized formalization can be disconcerting and is being debated. Should the approach be made more normative, and a School of geoprospective be created? Or should the freedom of practices be retained and the experimentation of methods combining diverse contributions be encouraged?

Figure 1. 1

 1 Figure 1.1 Geoprospective, at the interface of several fields of research.

  2001, the UNO launched an assessment of the impact of human activities on ecosystem services called "Millennium Ecosystem Assessment" (MA) that was published in 2005. between global and local socioecological processes by using qualitative storyline and quantitative modeling mainly based on IMAGE and IMPACT models. IMAGE model (Integrated Model to Assess the Greenhouse Effect) estimates the consequences of climate changes interaction on Land Use and Land Cover and the population at the global scale. IMAGE also estimated the Greenhouse Gas (GHG) releases provoked by these changes and the consequences on biodiversity. The IMPACT Model (International Model for Policy Analysis of Agricultural Commodities and Trade) was developed to assess the consequences of global changes on food availability and poverty by integrating data about climate change, water demand and availability, crops production, economy and regulation of the agriculture market. The model simulates the operation of commodity markets and the behavior of economic stakeholders in order to estimate the supply and demand for food products. The use of these two models is applied at national and continental scales. Even if they integrated a spatial representation of the results, we cannot consider that they are spatially explicit.

The scope of this work was to establish an overview of the state of the environment, ecosystem services, and human wellbeing and to assess their evolution within 2050 by integrating scenarios of human activities development and climate change. The scenarios of the MA integrate feedbacks between social and ecological systems and they also take into account the linkages Finally, the French consortium AllEnvi (Alliance nationale de recherche pour l'Environnement) that gathers 12 founders from the highest research institutions produced in decembre 2016 a report on the evaluation of 307 scenarios applied on environmental prospective

[START_REF] De Menthiere | Visions du futur et environnement: Les grandes familles de sce ´narios issues d'une analyse de prospectives internationales relatives a `l'environnement[END_REF]

. The study shows that the scenarios can be organized into 11 huge families that indicate the different trends of social and environmental evolutions in different countries. These scenarios are applied at national, continental (Asia, Europe, Mediterranean basin, etc.), or global scales. Most of them are based on expert knowledge and are not spatially explicit.


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Talkmine, a workflow for the prediction of the interactions between secretome and surfaceome in the dialogue between cellular types

Manon Connault" Jérémy Tournayre, Céline Boby, Muriel Bonnet, Nadia

Goue

To cite this version:

Manon Connault" Jérémy Tournayre, Céline Boby, Muriel Bonnet, Nadia Goue. Talkmine, a workflow for the prediction of the interactions between secretome and surfaceome in the dialogue between cellular types. JOBIM, Jul 2021, Paris -(Congrès virtuel), France. hal-03332138v2


Frederic B Ribeiro

Cedric Plesse

Giao T M Nguyen

Sofia M Morozova

Eric Drockenmuller

Alexander S Shaplov

Frederic Vidal

All solid-state ionic actuators based on polymeric ionic liquids and electronic conducting polymers

Keywords: ionic actuators, electronic conducting polymers, polypyrrole, polymeric ionic liquids

Ionic electro-active polymers (EAP) are promising materials for actuation and sensing. In order to operate in open-air, they are usually built in a trilayer configuration where the internal polymer membrane is soaked with an exogenous electrolyte and sandwiched between two electronic conducting polymer (ECP) layers. The use of exogenous electrolytes can be a limitation in several applications since it may lead to evaporation issues and leakage. Moreover, the soaking step, necessary to introduce the electrolyte in the device, can become tricky as soon as microdevices are considered. In this work we describe the synthesis and characterization of truly "all-solid-state" ionic actuators by using polymeric ionic liquids (PILs). PILs are a new class of polyelectrolytes presenting ionic liquid-like ions along their polymer backbone. First, ECP electrodes containing PIL are synthesized by vapor phase polymerization and their thickness and electronic conductivity are characterized. Then, electrodes and PIL-based membranes are assembled into a trilayer configuration as a proof of concept of solid-state ionic actuator. Under 1.75V, a strain difference about 1% is reached.

INTRODUCTION

Smart materials and structures based on electroactive polymers (EAPs) represent a fast growing and stimulating field of research and development. EAPs are materials capable of changing dimensions and/or shape in response to suitable electrical stimuli. Since many of these characteristics can also describe natural muscle tissues from an engineering point of view, it is not surprising that EAP transducers are sometimes also referred to as "artificial muscles" [START_REF] Shainpoor | Ionic polymer-condctor composites as biomimetic sensors, robotic actuators and artificial musclesa review[END_REF] . In this field, electronic conducting polymers (ECPs) have attracted great attention, notably because they have some important advantages like low driving voltage and inherent electronic conductivity. Their volume changes are due to the insertion/expulsion of charge balancing ions occurring during the oxidation/reduction process of the ECP electrodes. When the liquid electrolyte is incorporated into a polymer membrane and combined with two ECP electrodes into a trilayer configuration [START_REF] Alici | Conducting polymer microactuators operating in air[END_REF][START_REF] Khaldi | Conducting interpenetrating polymer network sized to fabricate microactuators[END_REF] , open-air actuation can be obtained. Under low voltage stimulation (< 2 V) opposite redox processes are occurring in each electrode leading to opposite volume variations and then to an overall bending deformation of the device. The central ionic conducting membrane, being usually either an electrolyte-soaked porous membrane or an electrolyteswollen polymer gel, plays a critical role. First, it acts as electrolyte reservoir to provide the ions necessary to the redox process of the ECP electrodes. Second, the overall response speed of the actuator, limited by diffusion of ions, is directly related to the ionic conductivity of the membrane. Finally, the membrane usually insures the mechanical robustness of such electrochemomechanical devices.

Central membranes combining both high ionic conductivity and good mechanical properties have been already demonstrated by using soaked porous membranes (i.e. PVDF) [START_REF] Wu | Fast trilayer polypyrrole bending actuators for high speed applications[END_REF] or swollen-ones (i.e. gel or IPN) [START_REF] Osada | A polymer gel with electrically driven mobility[END_REF][START_REF] Okuzaki | Ionic liquid/polyurethane/PEDOT:PSS composites for electroactive polymer actuators[END_REF] by ionic liquids and led to actuators with good performances, compatible with microsystem processes and presenting fast response speed 7,8,9,10, . Nevertheless, the presence of an exogenous liquid electrolyte makes these materials considered as "wet" EAPs and despite the advantage offered by these ionic liquids-based actuators a risk of leakage during storage or operation cannot be excluded. Moreover, the introduction of liquid electrolyte, by swelling or soaking, can be time consuming and involves undesired handling step that can be tricky, especially as soon as microactuators are considered. Therefore, it is desirable to convert "wet" IL-based actuators into trully solid-state device. Then, we propose here to use polymeric ionic liquids (PILs) as solid polymer electrolyte (SPE). Polymeric/polymerized ionic liquids or poly(ionic liquid)s (PILs) refer to a special type of polyelectrolytes which contains ionic liquid-like species which are covalently bonded to a polymer backbone [START_REF] Holly | Synthesis and Electric Field Actuation of an Ionic Liquid Polymer[END_REF][START_REF] Washiro | Highly ion conductive flexible films composed of network polymers based on polymerizable ionic liquids[END_REF][START_REF] Huadong | Atom Transfer Radical Polymerization of Styrenic Ionic Liquid Monomers and Carbon Dioxide Absorption of the Polymerized Ionic Liquids[END_REF][START_REF] Nakajima | Preparation of thermally stable polymer electrolytes from imidazolium-type ionic liquid derivatives[END_REF][START_REF] Dezhi | Solid state actuators based on polypyrrole and polymer-in-ionic liquid electrolytes[END_REF][START_REF] Mcewen | Electrochemical properties of imidazolium salt electrolytes foe electrochemical applications[END_REF] . On the opposite of classical polyelectrolytes requiring the presence of a solvent, PILs benefit from the fact that their ionic charges have chemical structures similar to the ones of ionic liquids allowing their dissociation and mobility without any additional solvent. Frequently, PILs contain cations such as imidazolium, pyrrolidinium, pyridinium, ammonium or phosphonium, which are either chemically bonded to the main polymer chain or presents as free counter ions. It is worth noting that although ILs are in a liquid state near room temperature, PILs are in fact solid in most cases, except a couple of exceptions [START_REF] Nakagawa | Liquid and polymer gel electrolytes for lithium batteries composed of room-temperature molten salts doped by lithium salt[END_REF] . The major advantages of using a PIL instead of an IL are the enhanced mechanical stability, improved processability and durability over the IL species. Such chemical architecture allows combining all beneficial properties of ionic liquids with those of classical polyelectrolytes. They offer the unique possibility to develop truly all-solid-state electrochemical devices in many exciting technologies such as batteries, fuel cells, supercapacitors and electrochromic devices 18-20, 21, 22 . In this paper, we report first the synthesis and characterization of ECP+PIL-based electrodes by vapor phase polymerization (VPP). Then, these electrodes are assembled with a flexible PIL-based SPE membrane combining both ionic and mechanical properties. The resulting device is stimulated under an applied voltage of 1.75V and a strain difference of 1% is reached demonstrating the proof of concept of a truly all-solid-state ionic actuator.

EXPERIMENTAL SECTION

Materials

Iron (III) p-toluene sulfonate (Fe(C 7 H 7 SO 3 ) 3 55% in n-butanol, Clevios C-B 54 V3, Heraeus), poly(ethylene glycol) methyl ether methacrylate (PEGM, Mn = 475 g mol -1 ), were used without further purification. Acetonitrile, ethanol and methanol were used as received. Pyrrole (Sigma -Aldrich) was distilled before use. The polyimide PIL (PI PIL), PILco-PEGM, and PIL C1 were synthesized as described elsewhere (being published) (Fig. 1).

Preparation of the PI PIL-based SPE central membrane

The central membrane of the actuator was prepared by casting a solution of the PI PIL by solubilizing it in tetramethylurea (TMU) (Fig. 2). For that, 0.15 g of PI PIL were solubilized in 9 mL of TMU for 5 days at 70 °C, then the solution was evaporated in a teflon dish at 50 °C. Finally, to remove the remaining solvent, the film was dried under dynamic vacuum at 70 °C for several days. This method allowed to get films with thickness about 0.17 mm. It should be underlined this PI PIL possesses both mechanical properties brought by its backbone chain (Figure 2, red) and ionic conductivity properties brought by its pending chains. Per pending chain, there is an average of 10 counter-ions. Its ionic conductivity has been measured at 1.2.10 -5 S/cm at 25 °C.

Synthesis of the electrodes

Electrodes with PPy + PIL C1 were prepared through the following procedure (Fig. 3): 0.2 g of PIL C1 were solubilized in 1 mL of acetonitrile then stirred until complete solubilization. Then 0.1 g of PEGM and 0.7 g of oxidant (i.e. Iron (III) p-toluene sulfonate 55% in n-butanol) were added to it. Finally, the solution was filtered through a syringe with a porosity of 0.2 μm to avoid the presence of dusts. This oxidant solution was spin-coated onto a glass substrate, dried 2 minutes on a hot plate at 60 °C to evaporate the solvent (i.e. butanol and acetonitrile). When the coating is almost dry, the Fe (III) tosylate starts to form crystals and the color of the coating changes to dark yellow indicating that the solvent is now evaporated. Then, the substrates were put under a vacuum bell in the presence of 2 mL of distilled pyrrole at 25 °C for 2h. The vapor-phase polymerization (VPP) was carried out in a simple single-chamber under static vacuum with a heater which provides the possibility to control the temperature. Once the electrodes were synthesized they have been dried for 1 h at room temperature until residual vapors had evaporated. Following the VPP, the samples were washed and lifted-off a couple of seconds in methanol and in warm deionized water at 45 °C to remove unreacted monomers or oxidant as well as short oligomers and byproducts remaining after the polymerization [START_REF] Winther-Jensen | Vapor-phase polymerization of 3,4-Ethylenedioxythiophene: A route to highly conducting polymer surface layers[END_REF][START_REF] Im | Systematic control of the electrical conductivity of poly(3,4ethylenedioxythiophene) via oxidative chemical vapor deposition[END_REF] .

Figure 2: casting procedure of the polyimide polymeric ionic liquid (PI PIL)

Synthesis of the actuators

To make the trilayer actuators, 0.5 mL of a solution of 0.15 g of PIL-co-PEGM in 2 mL of acetone were sprayed in both sides of the PI PIL membrane by using an airbrush (volume flow of 120 Nl/h). Since PIL-co-PEGM is very sticky it acts as an ionic conductive glue. Finally, electrodes of PPy + PIL C1 were stuck from each side of the central membrane (Fig. 4).

Characterizations

The ionic conductivity of the polymeric ionic liquids was measured by electrochemical impedance spectroscopy using a VSP 150 potentiostat (Biologic SA). Samples of 1 x 1 cm were placed between two gold electrodes and a sinusoidal voltage E with a 2πf pulsation is applied. The resultant current is monitored and by plotting the imaginary part -Im Z (2πf) vs the real part Re Z (2πf) is then possible to determine the bulk resistance. The ionic conductivity was calculated by using the following formula: 𝜎 (S/cm) = (1/Z)*(l/a) where z is the real part of impedance which is obtained by using the LCR bridge, l the thickness and a the area of the sample. The film thickness was measured by a DekTak 150 profilometer (VEECO). The electronic conductivity of the polymer coatings was measured by using a four-point probe on 3 x 3 cm substrates. During a measurement sequence, the current through the sample is changed from a low level where the potential drop over the sample is in the μV range to the current level where the potential is well above 10 mV. To eliminate errors from thermovoltages and voltmeter offsets, two current pulses of opposite signs are used for each measurement point. To measure the actuation, beam films of 1 x 3 cm were maintained horizontally with steel clamps. The displacements were obtained by applying a voltage between ± 1.75 V. The deformation of the film was recorded with a laser displacement sensor (ILD 1401-5, Micro-Epsilon) and from the resulting displacement signal, the strain difference between the two outer electrodes, ε, was calculated according to Sugino et al. where D is the half of the peak-to-peak displacement, W is the thickness of the actuator and L is the distance from the clamped beam to the projection of the laser spot.

RESULTS AND DISCUSSIONS

3.1 Optimization of the film electrodes ECP electrodes were first synthesized and characterized separately (i.e. thickness and electronic conductivity) from the actuator. The vapor phase polymerization (VPP) method has been chosen to synthesize the electrodes since it is an efficient and easy technique to synthesize thin ECP layers with high electronic conductivity. [START_REF] Lawal | Vapour phase polymerization of conducting and non-conducting polymers: a review[END_REF] It is expected also that this procedure will lead to sufficient electroactivity to consider the use of these electrodes in all-solid-state actuators. Beyond that, the electrodes should display also high ionic conductivity to allow efficient redox process during actuation. As a consequence, PIL have to be introduced also during the VPP synthesis of the electrodes. Then the resulting electroactive electrodes will be a composite of PPy and PIL C1. Finally, since the electrodes will be finally glued on both sides of the central membrane in the final device they must be thick enough to be handled easily (i.e. thickness around 5 μm).

PIL C1 content effect. Since both of electronic and ionic conductivities in electrodes are necessary to get an actuation, PIL is introduced directly in the oxidant solution for the VPP of Py. The influence of PIL content on thickness and electronic conductivity of PPy + PIL C1 electrodes was investigated. These film electrodes were prepared by spincoating the oxidant solution in the presence of PIL C1 at 500 rpm, 1200 rpm/s for 30 s and carrying the VPP at 25 °C for 2h. Figure 5 shows the evolution of the final thickness and corresponding electronic conductivity of such electrodes regarding the PIL C1 content. First, when PIL C1 content in the oxidant solution is increasing the thickness of the electrode increases from 1.5 to 8 µm. This behavior can be explained by the increase of solid content in the final electrode and by the intrinsic viscosity of the PIL C1 which make the spin-coated oxidant solution thicker. At the same time, a decrease of electronic conductivity from 4.3 to 0.3 S/cm is observed. This trend can be attributed by the increase of electronically insulating components in the electrode making it harder for the PPy chains to growth and to reach the percolation. Finally, in order to have a compromise between ionic charge carriers in the electrodes, electronic conductivity and a sufficient film electrodes thickness, it has been chosen to incorporate 8 % wt. of PIL C1 inside them. Synthesis parameters effect. To reach an electronic conductivity as high as possible it has been decided to investigate and optimize the VPP synthesis conditions to assess their influence on the electrode electronic conductivity.

In that purpose, the properties (thickness and electronic conductivity) of the PPy + PIL C1 (8 % wt.) synthesized electrodes were studied as a function of the spin-coating speed (from 500 to 1500 rpm), the VPP duration (from 90 to 190 min) and the VPP temperature (from 22 to 30 °C).

Fig. 6 summarizes the influence of all these parameters on the electronic conductivity of PPy + PIL C1 film electrodes.

Regarding the influence of the spin-coating speed the electronic conductivity is a slightly decreasing from 1.2 to 0.4 S/cm when the spin-coating speed increases from 500 to 800 rpm and then remains constant around 0.4 S/cm from 800 to 1500 rpm. Concomitantly, the thickness is also decreasing when the rotation speed is increasing, from 2.4 µm to 1.5 µm. Usually highest electronic conductivities are obtained for thin film (i.e. high rotation speeds) which is not the case here. This result seems to indicate that percolation of PPy chains in the ECP-PIL electrode requires sufficient final thickness of the film to occur and may indicate some 3D structural disorder [START_REF] Zhang | Conductivity of metallic films and multilayers[END_REF] .

Thickness and electronic conductivity are slightly increasing as a function of VPP duration, from 2.5µm and 1 S/cm (90 min) to 5 µm and 2.5 S/cm (180 min) respectively. Once again it seems that thickness and electronic conductivity are evolving with the same trend and that 3D percolation of PPy chains need sufficient thickness to occur. The polymerization need to be carried out at least during 120 min to reach a threshold time [START_REF] Kim | Fabrication and characterization of conductive polypyrrole thin film prepared by in situ vapor-phase polymerization[END_REF] . The plateau value obtained after 150 min suggest all oxidant has breacted and the polymeric chains do not grow anymore.

With the increase of the VPP temperature, final thickness of the electrodes is slightly increasing from 2.3 µm (22°C) to 3µm (30°C) while the electronic conductivity is significantly decreasing, from 1 to 0.15 S/cm respectively. It is worth mentioning that no film is obtained above 30°C. This trend is opposite to the one observed for the two other parameters since electronic conductivity is here inversely proportional to the final thickness. Knowing that an increase of VPP temperature increases both polymerization kinetic constant and Py monomer vapor concentration, the increase of polymerization rate may result in a decrease of the molecular weight of PPy chains and an increase of the structural disorder.

Finally, by proper choice of synthesis conditions (i.e. 500 rpm, 22 °C, 2h), it was possible to produce homogeneous and thick conductive PPy-PIL electrodes on glass substrates. The "optimized" conditions led to films with an electronic conductivity of 2.5 S/cm and a thickness of 5 μm. Although this electronic conductivity value is much lower than values which can be obtained for polypyrrole electrodes made by vapor phase polymerization (up to 1000 S/cm for nanometer thick films [START_REF] Fabretto | Vacuum vapour phase polymerized poly(3,4ethylenedioxythiophene) thin films for use in large-scale electrochromic devices[END_REF] ) it should be underlined these films are much thicker and they contain a polymeric ionic liquid inside. Moreover, electronic conductivities between 10 -6 S/cm and 0.1 S/cm were reported elsewhere for casted films made of an electronic conducting polymer (PPy, PANI or PEDOT) and a polymeric ionic liquid [START_REF] Marcilla | New Organic Dispersions of Conducting Polymers Using Polymeric Ionic Liquids as Stabilizers[END_REF] . The values obtained here are then 25 times higher which prove that VPP polymerization in the presence of PILs is an asset for elaborating electrodes. In order to assess the electroactivity of these electrodes, the synthesis of PPy+PILC1 composite was carried out onto an ITO glass and resulting electrodes were washed in warm water and cold MeOH and finally cycled in an electrolyte (0.5 M LiTFSI in water). Figure 7 shows the cyclic voltammetry of such electrode between -0.9 and + 0.5 V vs Ag. A voltamogram with well-defined oxidation and reduction peaks at + 0.05 V and -0.5 V respectively is obtained and indicates that such electrodes can efficiently undergo the redox processes necessary for actuation in the final device.

Ionic conductivity of PILs

The ionic conductivity of all PILs used in this study has been measured by electrochemical impedance spectroscopy (EIS). Figure 8 shows the ionic conductivity behavior versus the temperature of both PI PIL which has been used as central membrane, PIL C1 which was incorporated in the electrodes and PIL-co-PEGM. Since the copolymer PIL-co-PEGM possesses both a high ionic conductivity and a very sticky behavior it has been chosen to use it as an "ionic conductive glue" to stick the electrodes on both sides of the central membrane in order to allow to counter-ions to move through all actuator layers (from one opposite electrode to the other one). It is worth to note regardless which PIL is used in the electrodes or to stick the electrodes to the central membrane since the counter-ion is the same over the thickness of the actuator (TFSI -) no anion exchange will occur. PI PIL and PIL-co-PEGM are the ones which possesses the highest ionic conductivities at room temperature, 1.2.10 -5 S/cm and 1.5.10 -5 S/cm at 25 °C, respectively. PIL C1 is the one which possess the lowest ionic conductivity at 25 °C with 8.4.10 -7 S/cm. By increasing the temperature, the ionic conductivity increases as the mobility of the ions rises to finally reach nearly 10 -3 S/cm at 100 °C. It should be underlined that PI PIL and PIL-co-PEGM possesses quite high ionic conductivities for PILs and all PILs have a sufficient ionic conductivity at room temperature to consider them in all-solid-state actuators.

Actuation results

The all-solid-state device was then assembled manually by pressing the PPy+PIL C1 electrodes on each face of a 170 µm thick PIL PI membrane. To efficiently bond the electrodes, the ionically conducting glue PIL-co-PEGM was first sprayed on PIL PI membrane. The final structure of the solid-state actuator is then "PPy+PIL C1 electrode//PIL-co-PEGM glue//PIL PI membrane//PIL-co-PEGM glue// PPY+PIL C1 electrode". A square wave potential of +/-1.75V is then applied to the device and the resulting bending displacement is recorded with a laser displacement sensor. Typical time profile of the applied voltage and resulting free displacement and electrical current of the actuator are depicted in Fig. 9. First it can be observed that during electrical stimulation a reversible bending movement is observed, demonstrating the feasibility of an all solid state ionic actuator. It is interesting to point out that bending occurs systematically toward the reduced electrode, i.e the volume of the electrode is decreasing during the reduction process. Indeed, charge compensation of the redox process can occur according to two mechanisms, i.e mobile anion et non-mobile anion mechanism [START_REF] Wang | Visualizing ion transport in conjugated polymers[END_REF] . In the case of mobile anion mechanism, oxidation/reduction of ECP chain will generate/remove positive charges along the polymer backbone and the electroneutrality will be insured by anions insertion/expulsion. The resulting volume change is then a volume expansion during oxidation and a volume contraction during reduction. In the case of this all solid-state actuator, free ion species in every layer, i.e. membrane, glue and electrodes, are TFSI -anions. The direction of bending of the actuator is then consistent with the charge of the free ions and the mobile anion mechanism.

Mechanical response versus electrical stimulation is observed with the free strain varying from about 1 % which is in the order of values obtained for ECP based ionic actuators [START_REF] Temmer | In search of better electroactive polymer actuator materials: PPy versus PEDOT versus PEDOT-PPy composites[END_REF] . The maximum displacement tends to a plateau after for 20 min and reflects a very slow electrochemical system which is the consequence of an all solid-state system. It should be underlined that actuation tests with PEDOT:PSS electrodes which possess almost the same electronic conductivity of those PPy + PIL C1 electrodes (i.e 2 S/cm) but without PIL inside them were done and led to no actuation at all. It highlights the need of PIL inside the electrodes to insure the ionic continuity through all the sample.

Figure 1 :

 1 Figure 1 : Chemical formulas of PI PIL, PIL-co-PEGM and PIL C1

Figure 3 :Figure 4 :

 34 Figure 3: Synthesis route of the film electrodes made with PPy + PIL C1

Figure 5 :

 5 Figure 5: Evolution of the thickness and the electronic conductivity of 3 x 3 cm PPy + PIL-C1 electrodes regarding the PIL-C1 content

Figure 6 :

 6 Figure 6: Influence of spin-coating speed, VPP duration and VPP temperature on the thickness and electronic conductivity of PPy + 8 % wt. PIL C1 film electrodes

Figure 8 :

 8 Figure 8: Ionic conductivity behavior of PI PIL, PIL C1 and PILco-PEGM measured by EIS regarding the temperature

Figure 7 :

 7 Figure 7: Cyclic voltammetry of PPy + PIL C1 electrodes in 0.5 M LiTFSI in water 50 mV/s at 25 ° C

Figure 9 :

 9 Figure 9: Left: square wave applied potential (± 1.75 V). Right: free displacement of actuators and current response. Displacement was measured at L = 3 mm distance from clamped end

CONCLUSIONS AND FUTURE WORK

This work reports the full fabrication of an all solid-state ionic actuator based on an electronic conducting polymer and polymeric ionic liquid. To the best of our knowledge it is the first time that this kind of actuators is reported in the literature. Although the proof of concept of this kind of actuators has been demonstrated these systems are much slower than classical conducting polymers-based actuators swelled in ionic liquids due to the lower value of ionic conductivities of PILs. So, in order to improve these performances and more specifically the actuation rates, diffusion speed must be increased by developing PIL with higher ionic conductivities and diffusion distances must be decreased by developing thinner devices as already demonstrated in the case of microactuators. It will be the focus of future works.