Hajar Saddoug
email: hajar.saddoug@etu.sorbonne-universite.fr

Aryan Rahimian
email: rahimian_aryan@yahoo.fr

Bertrand Marne
email: bertrand.marne@ens-lyon.fr

Mathieu Muratet
email: mathieu.muratet@lip6.fr

Karim Sehaba
email: karim.sehaba@liris.cnrs.fr

Sébastien Jolivet
email: sebastien.jolivet@unige.ch

Review of the Adaptability of a Set of Learning Games Meant for Teaching Computational Thinking or Programming in France

Keywords: Serious Games, Meta-design, Instrumental Genesis, Computational Thinking, Programming

Our work is part of a broader research project on how French teachers and trainers can appropriate learning games dedicated to computer science and programming. To foster this appropriation, we aim to implement a meta-design approach that favours instrumental genesis. In this article, we describe our review of a selection of learning games to identify whether they are suitable for this approach. We introduce a set of rather generic and reusable criteria to characterize the instrumentalization of serious games. With these criteria we thoroughly review 10 games among 48 selected. Thus, for each game selected, the identified criteria point out the availability of means and tools allowing teachers and trainers to understand the game, but they also assess adaptability of the latter in relation to pedagogical needs. Our results show that the adaptability of most of these 10 games remains weak and out of reach for many teachers and trainers. Indeed, none of the reviewed games were able to meet the requirements set out in the framework of the meta-design approach.

INTRODUCTION

In our research context, education in France, the question of computer science education dates back to the 1970s and is characterized by a balance between two conceptions of what should be taught. On the one hand, there is the idea of teaching IT and computer science as a tool. On the other hand, the idea of computer science as an academic subject, with its own concepts and methods to be taught [START_REF] Baron | L'informatique comme objet d'enseignement à l'école primaire française ? Mise en perspective historique[END_REF]. After its demise years ago, computer science has made a comeback in French school curricula, where it is referred to as "computational thinking". According to Jeannette Wing, computational thinking involves five cognitive abilities: (1) algorithmic thinking, (2) abstraction, (3) evaluation, (4) decomposition, and (5) generalization [START_REF] Wing | Computational thinking[END_REF]. The French researcher Gilles Dowek [START_REF] Dowek | Les quatre concepts de l'informatique. 21[END_REF] has structured computer science into four concepts so that the content taught provides an accurate picture of the discipline itself: (1) digital information, (2) algorithms, (3) languages, and (4) computing machines. Thus, computer science is not reduced to coding, which constitutes only the final phase of the translation into a programming language. Conceived in such a fashion, computer science leaves the status of a tool for what it really is: a science with its own specificities and requiring it's a proper learning process. However, teaching computational thinking in France at both elementary and high school levels requires a major involvement from teachers [START_REF] Kradolfer | A Sociological Contribution to Understanding the Use of Robots in Schools: The Thymio Robot[END_REF] in order to tackle this new discipline, due to a lack of training (both pre-service and in-service).

Alongside these changes in computer science teaching, serious learning games have emerged and offer many advantages over traditional teaching tools. Indeed, many authors consider serious learning games as promising, especially for increasing learners' engagement and motivation [START_REF] Bouvier | A trace-based approach to identifying users' engagement and qualifying their engaged-behaviours in interactive systems. Application to a social game[END_REF][START_REF] Garris | Games, motivation, and learning: A research and practice model[END_REF][START_REF] Keller | Motivation in cyber learning environments[END_REF][START_REF] Malone | Making learning fun: A taxonomy of intrinsic motivations for learning. Making Learning Fun: A Taxonomy of Intrinsic Motivations for Learning[END_REF][START_REF] Prensky | Digital Game-Based Learning[END_REF], while others consider these tools to foster a more constructivist learning [START_REF] Bogost | Persuasive Games: The Expressive Power of Videogames[END_REF][START_REF] Bogost | [END_REF][START_REF] Brunet | Vers un modèle de scénarisation pour l'enseignement de la pensée informatique à[END_REF][START_REF] Gee | Deep learning properties of good digital games: How far can they go?[END_REF][START_REF] Ryan | Deep Learning Games through the Lens of the Toy[END_REF]. Regarding teaching computer science and programming, many serious games exist [START_REF] Miljanovic | A Review of Serious Games for Programming[END_REF][START_REF] Vahldick | A review of games designed to improve introductory computer programming competencies[END_REF], but their appropriation by teachers remains scarce. To tackle this issue, we make the hypothesis that a participatory design method such as metadesign could be suitable because it is promoting instrumental genesis [START_REF] Rabardel | Les hommes et les technologies: Une approche cognitive des instruments contemporains[END_REF][START_REF] Rabardel | From artefact to instrument[END_REF]. Metadesign is an advanced participatory design method, in which the end users ("owners of problems"), in our case the teachers, are intimately involved in the initial design phases. But, and that is the reason for metadesign relevance in solving appropriation problems, users must also have the means to continue to act as designers during the use phases of the artefacts. It is possible, thanks to underdesign, which Fischer et al. [START_REF] Fischer | Meta-design: A manifesto for end-user development[END_REF] define as: "[…] underdesign aims to provide social and technical instruments for the owners of problems to create the solutions [of their problems] themselves at use time". Therefore, in our case, the goal is to identify how teachers and trainers, who are the end users of serious games dedicated to programming, manage to take part in a meta-design approach through the instrumentalization of the artefact.

Nevertheless, in order to implement this metadesign approach, it is necessary to have flexible artefacts (in our case, serious games) providing functionalities allowing these end users (teachers or trainers) to monitor their use at different levels of abstraction and to adapt them accordingly, taking into account their context and needs. In this article, we carry out a review of learning games on computer thinking with a focus on the tools made available to promote the instrumental genesis and appropriation of these games by teachers. The goal is to assess adaptability of each of the games reviewed through a meta-design approach.

In the first part, we present our methodology, i.e. how we developed our assessment criteria, how we constructed our selection of games to be assessed and how we conducted the review. In the second part, we present and discuss the results of this review, before concluding in the last part.

METHODOLOGY

There are already several reviews of serious games for programming in the literature. Among the research that we have been able to consult, we have noticed that the focus is mainly on the content and the skills taught by the serious games reviewed [START_REF] Lindberg | Gamifying programming education in K-12: A review of programming curricula in seven countries and programming games[END_REF][START_REF] Malliarakis | Educational games for teaching computer programming[END_REF][START_REF] Miljanovic | A Review of Serious Games for Programming[END_REF][START_REF] Vahldick | A review of games designed to improve introductory computer programming competencies[END_REF]. According to some of these studies, such as Lindberg et al. [START_REF] Lindberg | Gamifying programming education in K-12: A review of programming curricula in seven countries and programming games[END_REF], there is a poor alignment between the skills taught in serious games (29 were reviewed) and those taught in the curricula (particularly in French). This tendency is also found in Malliarakis et al. and Miljanovic and Bradbury (Malliarakis et al., 2014;[START_REF] Miljanovic | A Review of Serious Games for Programming[END_REF], with respectively 12 and 49 games assessed (and many overlaps between these studies). However, these works never identified the possibility of an instrumental genesis, for instance through instrumentalization. Only Vahldick et al. [START_REF] Vahldick | A review of games designed to improve introductory computer programming competencies[END_REF] discuss the importance that editors tools can play in specific cases, yet without making it a criterion for their review (40 games reviewed).

Therefore, we conducted our own review by focusing on the ability of appraised games to have, on the one hand, monitoring capabilities that allow the teacher to understand how the game is used and, on the other hand, adaptation capabilities that allow the teacher to modify the game according to the results of the monitoring.

Learning Games Selection

To compile a list of games related to computational thinking for review, we combined the games we had already identified in other research (Marne, Muratet, et al., 2021;Marne, Sehaba, et al., 2021), with those from the above-mentioned systematic reviews, and with others searched on the web. We only retained serious games that are currently functional (for example, games using Flash technology are now very difficult to use), affordable or free. As a result, we have been able to identify 48 games that can be used to learn to code or computational thinking (Table 1).

We focus on serious games intended for learning computer science and programming in a school context, so we chose to exclude games with no real access to programming by the player, as well as those only available on mobile phones or tablets (restricted in French schools). We also merged the games with similar features to Scratch [START_REF] Resnick | Scratch: Programming for All[END_REF] or Blockly [START_REF] Fraser | Ten things we've learned from Blockly[END_REF], both of which are microworlds [START_REF] Papert | Microworlds: Transforming education[END_REF] offering programming with blocks of instructions.

Then, we filtered the list of games, while sorting and categorizing the games by considering the following characteristics:  Similarities and differences between the games;  Advantages and disadvantages of the tools available within or with the games;  Categories (e.g. age, field, cost);  Type of training (when provided by the game): self-training, traditional training, etc. This classification allowed us to refine the list to focus on a selection of 10 games (out of 48) that have little in common and that corresponds well to our objective: to identify serious games focused on learning computer thinking and programming that could be adapted or easily appropriated by teachers and trainers, i.e. allowing the implementation of a meta-design context. Henceforth, each game selected for review is associated with a separate category.

Preparation of the Assessment Framework

In order to establish our assessment framework, we identified several criteria. First, we identified three stages related to the possible adaptations that could be made by teachers or trainers to the listed games. For each of these three stages (before, during and after), we identified, as a criterion, specific types of support to adaptation:  Before Adaptation: availability of tutorials and explanations in different formats, regarding how to handle the game and/or how to use it for other training purposes.  During Adaptation: ability to check for errors during the game modification.

 After Adaptation: availability of an overview of the modifications made to the game and/or the presence of additional help (human or interactive digital maintenance such as forums, FAQs, etc.) Furthermore, as a follow-up to this preparatory step, we defined more refined and easily measurable criteria. These criteria are detailed in the next section.

Refined Criteria for the Review

The purpose of this study is not to highlight some of the serious games and disqualify others. The purpose is to review the serious games, to sort them out with fine-grained criteria, in order to provide a clear framework covering both convergences and divergences among the adaptable serious games dedicated to the teaching of programming or computational thinking.

Given its subjectivity, we were reluctant to use a score system, especially as the main point of our framework was to indicate the actual availability of the defined criterion. Accordingly, we referred to the criterion as "available" or "not available", and in the case of availability, we always comment on how the criterion is provided. However, for one of the criteria, the "Extent" of the scenario, we had to be able to be more precise, without going into too much detail for a quick analysis. Therefore, we settled on 3 possible states: small, wide or no scenario.

Once criteria were identified during our explorations, we decided to classify them. We identified 7 classes, each with different criteria, which are overviewed in Table 2. Adaptability is a crucial class of criteria for our framework, describing the ability of the game to be modified. It is broken down into 4 criteria:  Open Source Code: we checked the availability of the source code, its licence, and the availability of any digital resources that have been used.  Teacher Profile: we checked whether a specific account and profile exist for trainers or teachers, giving access to specific features (creating lessons, planning them, viewing logs, scores, etc.).  HMI Modification: we checked whether the game's interface could be modified.  Interaction Types: we checked whether it was possible to modify the existing interactions in the game (e.g. using other devices than the keyboard and mouse). The Editing class is distinguished from the Adaptability class, being narrower in scope and focusing on game content (task and scenario) modification. Its criteria are:

 Modifying Tasks: the ability to modify the content of an existing task, a level, its difficulty level, etc.  Adding Tasks: the ability to add tasks to the game's original ones.  Planning Tasks: the ability to reorder existing or self-created tasks (where possible), to allow for the creation of a new scenario.  Creating Scenarios: the ability to create a sequence of tasks.  Editor Provided: whether an authoring tool is provided to support creation, modification and planning tasks. For the purposes of our research, we introduced another class of criteria that we consider crucial: Training Ability. The purpose of this class is to identify, for instance, whether the system trains the teacher, or helps him or her to teach programming. Does the system clearly tell teachers what they can do with it? If it does, then how? Does the system provides feedback to the teachers during instructional design? Does the system provides suitable activities related to the concepts targeted? In other words, we need to pinpoint any information or means enabling teachers to get to grips with the system and to teach with it. It should be done by them either before implementing and editing a lesson in the system, or even during its previous design. In this class, we identified 4 criteria:

 Guidelines (for playing): describes whether information is available that may contribute to a better understanding and a proper handling of the game.  Pedagogical Guidelines (for editing): describes whether information is available that may contribute to understanding how to teach effectively with the system.  Didactic Support: describes whether there are any means to help teachers to better teach the targeted concepts (e.g. by providing suitable assignments).  Pedagogical Support: describes whether there is a support system that helps teachers implement efficient courses in the game. Thanks to the Monitoring class, we provide several criteria to describe the means made available to collect, consult and analyse logs of the learners' actions in the game. Indeed, an adaptation of a game by teachers or trainers is often triggered by discrepancies between the expected behaviours (of the learner-players) during the design stage of the game and the actual practices that may arise during the use stage. Such discrepancies are only perceptible, in some cases, through the implementation of a monitoring system, which logs interactions between users and the game. The logs collected can be transformed in order to reveal indicators, with a high level of abstraction, that might support teachers in making the necessary adaptations to ensure the learning process runs smoothly.

This class is related to Training Ability and Adaptability (more specifically the criterion Teacher Profile). Indeed, access to the logs requires a dedicated teacher interface. The criteria of this class are:

 Progress: identifies the availability of logs (indicators) of learners' progress in the game (levels completed, unlocked, levels replayed, etc.).

 Performance: identifies the availability of logs (indicators) showing the performance of each learner (scores, badges earned, etc.).  Background Information: identifies the availability of individual learner information (names, numbers, class, group, etc.).  Log Formats: describes the formats of the provided logs (raw or refined). We distinguish between refined format, i.e. information collected and presented with the aim of informing the user about the logs, and raw format, i.e. partial information that may be scattered throughout the system. The Community class has only two criteria. The first is the availability of User Forums and the second is the availability of Contact Information for the authors or the publisher of the game. We added this class to show whether external help might be available to teachers or trainers who would like to undertake editing the game.

The Scenario class is used to establish whether there is a scenario in the game, and if this scenario leaves the game tasks independent of each other. The 2 criteria are:

 Extent: indicates the extent of the scenario or narrative, i.e. the importance of a story or a background that links the different individual steps of the game (levels, stages, assignments, etc.) to each other. This criterion can have 3 values (wide, small, no scenario).  Stand-Alone Tasks: indicates how dependent the tasks (the units that constitute the scenario) are. With an extensive scenario, we will consider the dependency of the tasks. For instance, can the tasks be modified separately without affecting the overall scenario? There is one remaining criterion that could not be classified elsewhere: Programming Languages. This criterion is used to indicate whether the game allows the use of one or more programming languages. We have not included it in the Editing class, because it is about the language used for playing the game and not for editing it. We therefore propose a CS (Computer Science) Specific class. This class is the only class that is specific to games dedicated to learning computational thinking and programming.

Indeed, all the other classes above-mentioned contain criteria that are well suitable to review adaptability for any other kind of serious games.

Review Process

To review each game, we proceeded as follows: first, the same game was reviewed by two reviewers separately, note-taking the relevant information. In a second step, a synthetic table was filled in jointly. The time allowed for the review was different for each game. Thus, we noticed that, depending on the type of game, the average time for a full review was one hour. For some games, given their simplicity or minimalist interface, the review process was significantly shorter.

The review process required more than just playing the game, it also required time for the reviewers to get to grips with it and master it: reading guides, watching tutorials before playing, and testing the level editor when available. This analysis was characterized by a "meta-playing" approach, in which the reviewers had to be aware of the game and of themselves as players during the act of playing. This attitude is necessary for the reviewers to identify pros and cons of each game and to see, as they proceed, the similarities and differences between the games.

The review was carried out by class of criteria, and as soon as all the cells in a class were filled in, the reviewer moved on to the next class in the table. For some classes, such as Adaptability and Community, the reviewer had to spend more time than others, as additional research, especially on the web. For instance, the availability of open source code, the presence of forums dedicated to the game or any additional information present on users' blogs.

For each class, a comment column has been added to the table to provide additional information on the availability of certain criteria, but also to add specifics found in the game.

RESULTS AND DISCUSSION

Due to lack of space, we only included an excerpt of the synthetic review table of the 10 selected games in this paper in the appendix below (Table 3).

Concerning the class Adaptability, we noticed that many games have an Open Source Code (6/10) which is a positive element to support their modification. However, in the current selection, only a few games (3/10) provide specific interfaces for teachers (Teacher Profile). Among the games, the available features are very different: Algoblocs allows teachers to publish challenges or to enable/disable comments and forum options; AlgoPython allows teachers to create classes and assign students to them; finally, the game Code allows teachers to plan their courses, to structure them into units and chapters. The last two criteria of the class Adaptability are scarce. None of the games studied provide the possibility of modifying the game interface and only KoduGame allows the use of interaction peripherals other than the keyboard/mouse pair.

Regarding the class Editing, most games do not give any control over the scenario, some only allow the player to unlock the levels as they progress. Two games stand out: SPY and KoduGame. The first provides an option to add/remove/modify levels in the scenario by editing XML files. The latter allows teachers to create worlds in which they can define tasks, organize them, and specify assignments. Nevertheless, we noticed that in Code, tasks (called units) can be assigned to a course, but their content cannot be modified or reorganized.

For the class Training Ability, 6 games out of 10 provide guidelines and only 3 (Code, PyRates and Ceebot) are accompanied by pedagogical guidelines that provide information on the concepts covered by the game. The last two criteria in this class are dependent on the possibility to create/modify a task. Neither of the two games identified in the Editing class offers means to assist the teacher on either the pedagogical or didactic aspects.

Three games stand out in the class Monitoring (AlgoPython, CodinGame and Algoblocs). The players' actions are logged to provide teachers with dashboards displaying progress and performance indicators. Unfortunately, none of the games allows access to the data logged, preventing customized processing/analysis.

For the class CS Specific, only one game offers the player the possibility to manipulate several programming languages: CodinGame. It offers only text-based languages (no block-based languages), but several programming paradigms are possible, such as object-oriented, functional and imperative approaches. Therefore, teachers are free to choose their language from a wide range of 27 different programming languages.

Finally, the class Scenario shows us that most of the games (7/10) offer some kind of scenarios that links the different levels of the game. These links can be independent of the content of the tasks, as in PyRates, where the levels are structured by a back story including a theme and characters, but where each level can also be played independently of the other levels.

CONCLUSIONS

The research presented in this paper is part of the general problem of the appropriation of serious learning games dedicated to computational thinking and programming by teachers and trainers. More precisely, we seek to define how adaptable and flexible each game is in order to promote the metadesign approach and thus the instrumentalization dimension of the instrumental genesis.

This paper presents preliminary work on identifying criteria for assessing the adaptability of serious games. It also presents a review based on these criteria carried out on a selection of such serious learning games.

We introduce a review framework with 7 classes with between 1 and 5 criteria. Each class describes a component of adaptability for potential users with diverse profiles, ranging from a primary school teacher who is new to computing to an experienced computer scientist. With the exception of one of the classes and its associated criterion specific to computational thinking and programming (diversity of choice in programming languages), we believe that one of the main contributions of this work is to provide a structured set of adaptability review criteria that can be reused for any type of serious learning game.

We identified 48 games designed for learning computational thinking and programming. We made a selection of 10 games on which we used our review framework.

Thanks to this review of the ten selected games according to our criteria, we have shown that even if many of them offer open source code (criterion Open Source Code), few of them are easily adaptable (criteria HMI Modification, Interaction Type, Modifying Tasks, Adding Tasks, Planning Tasks, Creating Scenarios). When they are possible (e.g. SPY, PyRates, Kodu Game), the modifications most often require a good knowledge of programming (editors are non-existent, except for Kodu Game) and there are no training resources available to assist in these modifications.

Beyond the straightforward contributions of this work (a set of criteria for analysing adaptability that can be reused in other contexts and its implementation on reviewing 10 games), these results allow us to identify that the requirements for having a game dedicated to learning computational thinking or programming that allows implementing a metadesign approach are high and that none of the games reviewed here fully meet them. Our future research will therefore be directed towards identifying ways of making serious games intended for this type of learning more conducive to the implementation of a meta-design approach in an effort to foster their appropriation by teachers and trainers.

Table 1 :

 1 Initial list of 48 games, the 10 selected games are highlighted.

	Algoblocs	Code hunt	CodeWars	Elevator Saga	Hocus Focus	Pyrates	SQL Murder Mystery
	AlgoPython	Code Moji	Codin'Game Empire Of Code	Human Resource Machine	RoboCode	StarLogo
	Bee Bot	Code Monkey	Collabots	Flexbox Defense	Imagi	Ruby Warrior	Tynker
	Blockly	Code Monster Compute It Flexbox Froggy	KoduGame	Run Marco Unruly Splats
	Ceebot	CodeCombat	CSS Diner	Gladiabots	Le chevalier de la programmation	Scratch	Untrusted
	CheckIO	Codefi	Cyber Dojo	Grid Garden	Pixel	Screeps	Vim adventures
	Code	CodeGym	Duskers	Heartbreak	ProgAndPlay	SPY

Table 2 :

 2 Overview of the 7 classes of criteria used in our review.

	Classes	Related Criteria
	Adaptability	Open Source Code, Teacher Profile, HMI Modification, Interaction Types.
	Editing	Modifying Tasks, Adding Tasks, Planning Tasks, Creating Scenarios, Editor Provided
	Training Ability Guidelines (for playing), Pedagogical Guidelines (for editing), Didactic Support, Pedagogical Support
	Monitoring	Progress, Performance, Background Information, Log Formats
	CS Specific	Programming Languages
	Community	User Forum, Author/Publisher Contact Information
	Scenario	Extent, Stand-Alone Tasks

ACKNOWLEDGEMENTS

The authors would like to acknowledge The University Lumière Lyon 2 for the APPI 2020 Grant.

APPENDIX

The Table 3 below shows an excerpt of the full synthetic review table. The comments and some game metadata (URL and date of visit) are omitted. The full version of the table is available online: https://recherche.univ-lyon2.fr/meta-dect/SG_adapta bility_Review.xlsx On the table, to save space we replaced "Available" with "×" and "Not available" or "No scenario" with blank cells.


Keywords: Screening, colorectal cancer, second cancer, cancer survivors

Background: Colorectal cancer (CRC) has a high incidence worldwide, especially in highincome countries. In France, a national CRC screening program targeting residents aged 50-74 has been in place since 2009. Little is known about CRC screening practices in cancer survivors, even though some have an increased risk of developing a second cancer in the colorectum. This study aims to identify the barriers to CRC screening among cancer survivors.

Methods

: This cross-sectional study based on the French national VICAN survey included individuals diagnosed in 2010 with a cancer in one of 11 locations other than colorectum and interviewed five years after diagnosis about various health-related issues. Binary logistic regression was used to identify the factors associated with lack of up-to-date CRC screening in cancer survivors without cancer progression.

Results: Of the 2,935 cancer survivors included in the study, 35.3% reported undergoing a screening test in the previous two years. The rate of up-to-date CRC screening rose to 49.3% in survivors aged 51-75. Among these, lack of CRC screening in the recommended timeframe was associated with obesity, current smoking, non-use of complementary medicine, perceived financial difficulties, and poor access to general practitioners.

Conclusions: Barriers to CRC screening can be personal and/or institutional.

Introduction

Colorectal cancer (CRC) has a high incidence worldwide, especially in high-income regions, which accounted for almost 55.0% of the world's CRC cases in 2012 (International Agency for Research on Cancer 2018; Ferlay 2015). In men, CRC has the third highest incidence of any cancer site, after prostate and lung cancer, and represents 10.9% of new cancer cases. In women, it has the second highest incidence of any cancer site, after breast cancer, and accounts for 9.5% of new cancer cases. CRC is the second cause of death by cancer for both sexes and all ages (9.2% of cancer deaths in 2018).(International Agency for Research on Cancer 2018)

The same tendencies have been observed in metropolitan France. In 2017, CRC represented 11.2% of new cancer cases for both women and men, and CRC was the second cause of death by cancer (around 12.0% of all deaths by cancer). (Institut National Du Cancer 2018) In the past decades, CRC population screening programs have been implemented around the world. [START_REF] Navarro | Colorectal cancer population screening programs worldwide in 2016: An update[END_REF] In France, a national CRC screening program targeting residents aged 50-74 has been in place since 2009. This program, which is managed by local institutions based on national guidelines, targeted 16.8 million people in 2016-2017.(Institut National Du Cancer 2016, 2018) Every two years, targeted men and women are invited by a letter to undergo a fecal occult blood test (FOBT), followed by a colonoscopy in case of positive result. Their regular doctor then delivers the CRC screening kit. The FOBT is performed at home, and mailed free of charge to the laboratory. No specific recommendations on cancer screening have been formulated for cancer survivors in France. (Institut National Du Cancer 2013) In 2016-2017, the rate of participation in the French national CRC screening program was estimated at 33.5%. (Institut National Du Cancer 2018) This rate is lower than the EU's minimum and desired targets, set at 45% and 65%, respectively. (European Commission 2010) According to a review published in 2017, France is the European country with the thirdlowest participation rate (34.3%), far below the highest participation rate recorded in the Netherlands (68.2%). [START_REF] Navarro | Colorectal cancer population screening programs worldwide in 2016: An update[END_REF] In some studies, participation in the French national CRC screening program is slightly higher in women and increases with age. (Institut National Du Cancer 2018;Santé Publique France 2018) In other studies, French residents who do not undergo CRC screening most often live alone, have no complementary health scheme, or have given up care for financial reasons. (Institut National Du Cancer 2016;[START_REF] Goulard | Facteurs d'Adhésion au Dépistage Organisé du cancer colorectal : étude Fado-colorectal, France, décembre 2006-avril 2007[END_REF][START_REF] Sing | Characteristics of French people using organised colorectal cancer screening. Analysis of the 2010 French Health, Healthcare and Insurance Survey[END_REF] Regular doctors have also been found to play a key role in promoting CRC screening. Among women, participation in the French national CRC screening program has been shown to be higher in those who had previously undergone breast cancer and/or cervical cancer screening. Among men, smoking has been found to be a barrier to participation. A systematic review published in 2016 identified similar barriers to CRC screening, but found that women are less likely to undergo CRC screening. [START_REF] Wools | Colorectal cancer screening participation: a systematic review[END_REF] Three million individuals are living with a cancer diagnosis in France today. The risk of developing a second cancer in survivors is higher by 36.0% on average than the risk of developing cancer in the general population.(Institut National Du Cancer 2015) A large number of cancer survivors aged 50-74 are at risk of developing a second cancer in the colorectum. In this context, it is essential that CRC prevention and screening be promoted as part of the cancer survivor's follow-up.

The risk of developing a second cancer varies depending on the site of the first cancer. (Institut National Du Cancer 2013, 2015;[START_REF] Curtis | New malignancies among cancer survivors: SEER cancer registries[END_REF] According to a SEER-based study, the excess absolute risk (EAR) of the second cancer being colorectal is higher in survivors of upper aerodigestive tract, lung, uterine, or non-Hodgkin lymphoma cancer; by contrast, survivors of prostate or melanoma cancer do not seem to be at risk of developing a second cancer in the colorectum. [START_REF] Curtis | New malignancies among cancer survivors: SEER cancer registries[END_REF] Other studies have found that the EAR of the second cancer being colorectal is higher in male survivors of upper aerodigestive tract, esophagus, laryngeal, or lung cancer, but also in male survivors of prostate cancer; in addition, they have found that the EAR of the second cancer being colorectal is higher in female survivors with cervical cancer. (Institut National Du Cancer 2013, 2015) The increased risk of developing a second cancer in the colorectum may be due to shared risk factors, but also to the impact on noncancerous cells of cancer treatments like radiation therapy. [START_REF] Baxter | Increased risk of rectal cancer after prostate radiation: A population-based study[END_REF] Despite the fact that cancer survivors have an increased risk of developing a second cancer in the colorectum, studies are lacking on CRC screening practices among cancer survivors. The few studies available on the topic describe cancer screening rates in cancer survivors, and/or assess the health beliefs that shape screening practices. [START_REF] Corkum | Screening for new primary cancers in cancer survivors compared to non-cancer controls: a systematic review and meta-analysis[END_REF][START_REF] Mayer | Screening practices in cancer survivors[END_REF][START_REF] Trask | Cancer screening practices among cancer survivors[END_REF][START_REF] Shin | Knowledge, attitudes, risk perception, and cancer screening behaviors among cancer survivors[END_REF][START_REF] Yang | A Path Analysis on Factors Influencing Second Primary Cancer Screening Practices in Stomach, Colon, and Breast Cancer Survivors[END_REF] Generally, these studies do not specifically focus on CRC screening, but are also concerned with breast, cervical, and prostate cancer screening. To our knowledge, no study has been conducted on CRC screening practices using a large representative sample of cancer survivors and covering a wide range of tumor sites. Our study aims to estimate the rate of up-to-date CRC screening among cancer survivors five years after diagnosis, and to identify the personal and institutional barriers to CRC screening in these survivors.

Methods

The French national VICAN survey

This cross-sectional study was based on the French national VICAN survey. In this national representative study, cancer survivors diagnosed in 2010 were followed up for a period of five years to assess their life conditions.) Data were obtained from different sources:

-Patient interviews performed two and five years after diagnosis (2012/2015) to gather information on various health issues, including health condition, preventive health behaviors, etc.;

-The French national medico-administrative database (SNIIRAM), which records all care consumption data (generated inside and outside healthcare centers).

The VICAN survey focused on 12 types of cancer (breast, lung, colorectal, prostate, upper aerodigestive tract, bladder, kidney, thyroid, non-Hodgkin lymphoma, melanoma, cervical, and endometrial) accounting for the 4,174 cancer survivors who responded to the 5-year interview. Cancer survivors aged under 18 at diagnosis were excluded from the survey for legal reasons, and those aged over 82 at diagnosis were excluded because high attrition was expected. All participants provided written informed consent before participation. National ethics commissions approved the methodology of the VICAN survey.

Of the 13,046 cancer survivors invited to participate in the 5-year interview, 4,174 were finally included (32.0% crude response rate).

A weighting procedure was applied in order to ensure national representativeness in terms of gender, age, national insurance scheme, socioeconomic hardship, tumor site, and cancer progression since diagnosis. Cancer progression since diagnosis took into account the following criteria: metastasis (more than 12 months after cancer diagnosis) or second cancer, admission to a palliative care unit or treatment with chemotherapy, radiotherapy or targeted therapy (at least 24 months after cancer diagnosis) and death.(Bouhnik 2015)

Self-reported CRC screening practices

In the interview conducted five years after diagnosis, participants were asked the following question: "Have you ever undergone a FOBT or a colonoscopy?" The possible answers were: "Yes, less than two years ago/Yes, more than two years ago/No, never." The two modalities ("Yes, more than two years ago" and "No, never") were used to identify survivors who had not undergone CRC screening in the recommended timeframe (two years). These survivors were defined as not up-to-date with CRC screening.

Sample selection

Three categories of survivors were excluded from the statistical analyses (Figure 1): 1) survivors of colorectal cancer, because they already received colonoscopies as part of their regular follow-up; 2) individuals with cancer progression since diagnosis (cancer metastasis, second cancer, chemotherapy/radiotherapy administered more than two years after cancer diagnosis, palliative care), in order to obtain a homogeneous population of survivors who might benefit from CRC screening; and 3) individuals with missing data (<0.5%) related to the main variable of the study. Three age groups were defined based on the age recommended by national guidelines for CRC screening (i.e., 50-74 in the general population). The limits of the age group targeted for CRC screening were moved upwards by one year to ensure that included patients had enough time to undergo screening. The resulting age groups were: 26-50, 51-75, and 76-87.

Statistical analyses

Sensitivity analysis was used to address a potential bias related to the choice of the limits of the age groups. Univariate statistical analyses were performed using χ² tests for categorical variables and using Student's t-tests for continuous variables.

Then, for each age group, binary logistic regression models stratified by sex were used to identify factors independently associated with lack of up-to-date CRC screening. A backward stepwise process was used to select statistically significant factors in a multivariate model (probability threshold for inclusion in the model p-value=20%). Only variables remaining significantly associated with the outcome with a p-value≤5% were kept in the final model. First order interactions were systematically checked. An all available cases analysis method was applied to handle rare missing values. Another sensitivity analysis was performed to assess the robustness of the factors associated with no CRC screening, by considering "no CRC screening during lifetime" as outcome, instead of "in the past 2 years". Results of sensitivity analyses are provided as Online supplementary tables.

All statistical tests were done using the STATA 12.0 software.

Results

The sample of 2,935 individuals aged 26-87 (weighted mean age at the time of the survey=59.4, SD=12.8) was mainly composed of female survivors and survivors aged 51-75 (Online Supplementary Table 1). Most of the survivors aged over 51 had not completed high school and were retired at the time of the survey (Online Supplementary Table 1).

Five years after diagnosis, 35.3% of respondents (32.4% of women and 41.0% of men) reported undergoing a colonoscopy or a FOBT in the previous two years. The rate of up-todate CRC screening was higher in the 51-75 age group (Figure 1). This rate was higher in men than in women (p<0.001) for the pooled age groups; however, gender difference did not reach statistical significance for the age groups taken separately (Figure 1). CRC screening practices varied according to tumor site (Figure 2), but this variation did not reach statistical significance in the 51-75 age group after adjustment for age.

For cancer survivors eligible to participate in the national CRC screening program, the rate of up-to-date CRC screening was 49.3% [95%CI 46.5% to 52.1%]. A sensitivity analysis found a similar rate for survivors aged 50-74 (47.8%; n=1,762) and for survivors aged 51-74 (47.8%; n=1,658).

Factors associated with lack of up-to-date CRC screening five years after diagnosis

In univariate analyses, different sociodemographic, economic, medical, and behavioral variables were associated with lack of up-to-date CRC screening in survivors aged 51-75 (Table 1). The survivors more likely to report not being up-to-date with CRC screening were younger (p=0.016), lived alone (p=0.019), had perceived financial difficulties (p=<0.001), had poor access to GPs (p=0.004), were currently smoking (p=<0.001), and/or did not use complementary medicine (p=0.050). Socio-professional category and BMI were borderline significant.

The multivariate analysis (Table 2) confirmed that lack of up-to-date screening was significantly associated with perceived financial difficulties (p=0.004) (only in women, at least "Tight/I have to be careful": AOR (Adjusted Odd Ratio)=1.41 [95%CI 1.02 to 1.96]), poor access to GPs (p=0.010) (only in men: AOR=1.61 [95%CI 1.06 to 2.46]), non-use of complementary medicine (p=0.026) (only in women: AOR=1.54 [95%CI 1.10 to 2.14]), obesity (p=0.039), and current smoking (p=<0.001). It also tended to be associated with young age. However, it was no longer significantly associated with living alone. None first interactions was significant.

The same multivariate model was applied to the other two age groups (26-50 and 76-87) (Online Supplementary Table 2, Online Supplementary Table 3). In both cases, age at the time of the survey was statistically significant. In the 26-50 group, lack of up-to-date screening decreased as age increased (p=0.038), whereas in the 76-87 age group it increased as age increased (p=0.019). Perceived financial difficulties were associated with a higher lack of up-to-date screening in women from the 51-75 age group, but with a lower lack of up-todate screening in men younger than 51 (AOR=0.07 [95%CI 0.01 to 0.45]). Non-use of complementary medicine was only associated with lack of up-to-date CRC screening in younger women (AOR=2.11 [95%CI 1.19 to 3.75]).

Discussion

Main finding of this study

Five years after cancer diagnosis, and regardless of age, 35.3% of study participants reported undergoing a colonoscopy or a FOBT in the previous two years. In cancer survivors aged 51-75, this rate increased to 49.3%. This finding was expected, as individuals in this age group are automatically invited to participate in the French national CRC screening program. The 49.3% rate of up-to-date CRC screening observed in survivors aged 51-75 was higher than the EU's minimum target set at 45%.(European Commission 2010) However, it was far below the

EU's desired target (>65%).(European Commission 2010)

A high rate of up-to-date CRC screening was observed in prostate cancer survivors (n=377).

Conversely, half or less of the survivors of cervical, upper aerodigestive tract, breast, or lung cancer in our study reported undergoing CRC screening in the previous two years, even though they have an increased risk of developing a second cancer in the colorectum. (Institut National Du Cancer 2015;[START_REF] Curtis | New malignancies among cancer survivors: SEER cancer registries[END_REF]Institut National Du Cancer 2013) We identified several personal barriers to CRC screening. An association was found between a BMI of 30 or greater and lack of up-to-date CRC screening. Survivors with perceived financial difficulties were less likely to report up-to-date CRC screening. Individuals who continued smoking after receiving a cancer diagnosis were less likely to undergo CRC screening, despite an increased risk of developing a second cancer in the colorectum.

Conversely, survivors who used complementary medicine had a higher rate of up-to-date CRC screening.

Institutional barriers to CRC screening were also identified. Poor access to GPs was associated with a lower rate of up-to-date CRC screening in male survivors.

What is already known on this topic

As expected, the rate of up-to-date CRC screening was lower in younger cancer survivors. This is consistent with published studies, which found that young cancer survivors feel less concerned with the risk of developing a second cancer and are generally unaware of the importance of CRC screening. [START_REF] Goulard | Facteurs d'Adhésion au Dépistage Organisé du cancer colorectal : étude Fado-colorectal, France, décembre 2006-avril 2007[END_REF][START_REF] Mayer | Screening practices in cancer survivors[END_REF] This finding may be partly explained by the lack of national guidelines on screening for cancer survivors. Similarly, the rate of up-to-date CRC screening was lower in cancer survivors aged over 75. This is unsurprising, since for older cancer survivors the benefits of CRC screening have not been demonstrated. In fact, some authors recommend shared decision-making regarding CRC screening in this particular age group. [START_REF] Gangarosa | New Guidelines for Cancer Screening in Older Patients[END_REF] Personal and institutional barriers to CRC screening identified in our study was consistent with the associations revealed in previous studies.

Obesity is sometimes accompanied by physiological sequela and non-healthy behaviors.

Obese survivors are known to avoid CRC screening due to feelings of low self-esteem, body image disorder, or embarrassment-though it should be noted that the association between BMI and CRC screening practices has been found to be inconsistent in the general population. [START_REF] Seibert | National Disparities in Colorectal Cancer Screening Among Obese Adults[END_REF]Maruthur 2012) The association between smoking and poor cancer screening practices has been observed in the general population. [START_REF] Sing | Characteristics of French people using organised colorectal cancer screening. Analysis of the 2010 French Health, Healthcare and Insurance Survey[END_REF][START_REF] Wools | Colorectal cancer screening participation: a systematic review[END_REF] Unlike at-risk behaviors like smoking, healthy lifestyles are usually associated with proper cancer screening practices. This is consistent with published studies, which found that CRC patients who report using complementary medicines do so mainly to improve their general health and well-being. [START_REF] Sewitch | A literature review of complementary and alternative medicine use by colorectal cancer patients[END_REF] Studies have shown that financial insecurity causes individuals to give up care and cancer screening, even in the French context where screening tests and additional medical exams are free of charge. [START_REF] Goulard | Facteurs d'Adhésion au Dépistage Organisé du cancer colorectal : étude Fado-colorectal, France, décembre 2006-avril 2007[END_REF] In fact, it may be that other costs associated with CRC screening play a role in patients' decision not to undergo FOBT and/or colonoscopy. [START_REF] Hoover | Patients and caregivers costs for colonoscopy-based colorectal cancer screening: Experience of low-income individuals undergoing free colonoscopies[END_REF] Studies found lower rates of participation in screening programs among individuals with poor access to healthcare providers. [START_REF] Wools | Colorectal cancer screening participation: a systematic review[END_REF])

What this study adds

To our knowledge, this is the first study to investigate CRC screening practices in cancer survivors using a large national representative sample and covering 11 tumor sites. Our study took advantage of the wide range of sociodemographic, economic, medical, and behavioral data generated by the VICAN survey.

Several personal and institutional barriers to CRC screening were identified, which may be targeted in future recommendations for improving CRC screening in cancer survivors.

Our findings suggest that age thresholds for CRC screening should be adapted in function of the site of the first cancer, whenever this site is associated with an increased risk of developing CRC.

The lack of national guidelines on screening for cancer survivors is problematic given that a first cancer diagnosis increases the risk of developing a second cancer in most tumor sites (including the colorectum), particularly in individuals approaching the age of 50. Indeed, younger cancer survivors should be given information on the importance of developing regular CRC screening practices as early as possible: a cancer diagnosis could thus provide a teachable moment to improve preventive behaviors. [START_REF] Bluethmann | Grasping the 'Teachable Moment': Time Since Diagnosis, Symptom Burden and Health Behaviors in Breast, Colorectal and Prostate Cancer Survivors[END_REF] The high rate of up-to-date CRC screening observed in prostate cancer survivors is surprising, because of all the tumor sites under examination, prostate has been shown to be associated with the lowest risk of developing a second cancer in the colorectum. (Institut National Du Cancer 2015;[START_REF] Curtis | New malignancies among cancer survivors: SEER cancer registries[END_REF]Institut National Du Cancer 2013) This finding may reflect an age effect, as prostate cancer generally affects older individuals who are known to undergo CRC screening more frequently. Information on the increased risk of developing CRC after a first cancer is quite new, and in the absence of specific medical recommendations, those who undergo CRC screening are not necessarily the ones who most need it.

Smoking cessation should be encouraged as part of a global screening and preventive program.

While the gender difference observed in our study is difficult to explain, it can be expected to increase given that, since 2018, gynecologists in France are authorized to distribute FOBT kits to their (female) patients.

Limitations of this study

Our study has some limitations that must be acknowledged. Overall, a selection bias within our population resulting in an over-estimation of CRC screening rate cannot be excluded, as more severely affected survivors might be under-represented in our sample. A weighting procedure was applied in order to ensure the representativeness of our sample, taking into account cancer progression since diagnosis. Information on CRC screening was self-reported, which means that memory or social desirability bias may have occurred. However, we found it necessary to use self-reported data because the CRC screening procedure is not currently registered in the French medico-administrative database. In addition, it is possible that some of the participants who reported undergoing a colonoscopy did so in the context of a medical examination, and not following CRC screening. Nevertheless, a large body of literature indicates that self-reported measures of FOBT or colonoscopy uptake are acceptable, and that rates of self-reported CRC screening are consistent with CRC screening rates observed in the general French population. (Institut National Du Cancer 2018;[START_REF] Baier | Validity of Self-Reported Colorectal Cancer Screening Behavior[END_REF])

Conclusions

Our study conducted in a population of cancer survivors five years after diagnosis identified several personal and institutional barriers to CRC screening. A number of recommendations can be made based on our results. Cancer survivors and healthcare practitioners should be given appropriate information on the risk of developing a second cancer in the colorectum and on the importance of CRC screening practices. National guidelines should formulate recommendations for the preventive follow-up of cancer survivors, especially the most vulnerable (e.g. younger, smokers or obese survivors). Health agencies, healthcare providers, and researchers should consider the possibility of extending the national CRC screening program to younger cancer survivors. In order to reduce the negative impact of financial difficulties on CRC screening practices, a communication campaign should be launched to inform the general population and cancer survivors in particular about the free CRC screening tests. Lastly, CRC screening kits should be made available beyond medical consultations (for instance, in pharmacies) to reduce the difficulties associated with poor access to GPs.

Figure 2 :

 2 Figure 2: Prevalence of up-to-date CRC screening by age and cancer location Note: N=2,935. Values are presented as weighted percentages. There were no survivors of

Table 2 :

 2 There were no survivors of prostate, bladder, or endometrial cancer in the 26-50 age group, and no survivors of thyroid cancer in the 76-87 age group. Note: n=1,709. Values are presented as weighted percentages, unless otherwise noted. Up-to-date with CRC screening: cancer survivors who had undergone FOBT or colonoscopy in the previous two years. Logistic regression model of lack of up-to-date CRC screening among 51-75

	60%			54,9%		53,7%		58,7%
	50%	46,7%	50,0%	49,1%	49,5%		50,0%	46,6%
				42,5%	42,0%
	40%
				31,7%
	20% 30%	18,9% 19,4%	23,5%	19,9% 20,1% 25,5%	21,6%	15,8% 14,8%
	10%	12,3%		15,4%	15,0% 13,4%		16,5%	9,6%
						8,6%
	0%
				Age 26-50	Age 51-75	Age 76-87

a c Calculated excluding missing values.

91 1.35-2.69 <0.001 1.98 1.07-3.67 1.85 1.21-2.83

  Variable not selected by the stepwise procedure and forced in the multivariate logistic regression.Note: n=2,935. Values are presented as weighted percentages, unless otherwise noted.

	practitioners (sample Difficult/I can't manage without incurring	139 (17.5) 235 (13.7)	27 (6.3)
	quartiles) debts		Age 26-50	Age 51-75	Age 76-87	p-value
	Low (<1 st quartile) Missing	1.43 1.09-1.88 0.010 1.61 1.06-2.46 1.38 0.96-1.97 (n=797) (n=1,709) (n=429) 11 (1.3) 40 (2.4) 29 (6.6)
	Higher (>1 st quartile) Age at the time of the survey, weighted 1	1 44.4 (5.2) 61.4 (7.5) 79.5 (2.7) <0.001 1
	Note: n=1,645 after exclusion of 64 observations with missing values. Boldface indicates mean (SD)
	statistical significance (p≤0.05). Gender				<0.001
	Male		106 (13.3) 649 (38.0) (55.5)
	Female		691 (86.7)	1060	(44.5)
				(62.0)
	Living as a couple					0.171
	Yes		557 (70.0)	1221	(65.6)
				(71.4)
	No		240 (30.0) 486 (28.5) (34.2)
	Missing		0 (0.0)	2 (0.1)	1 (0.2)
	Level of education					<0.001
	< Less than high school degree	267 (33.5) 883 (51.7) (65.2)
	≥ High school degree or more	530 (66.5) 823 (48.1) (34.8)
	Missing		0 (0.0)	3 (0.2)	0 (0.0)
	Having a child					<0.001
	Yes		671 (84.2)	1546	(91.7)
				(90.5)
	No		126 (15.8) 159 (9.3)	34 (7.9)
	Missing		0 (0.0)	4 (0.2)	1 (0.4)
	Socio-professional category at the time of				<0.001
	No the survey	1		1	1
	Use of complementary Executive job		363 (45.6) 392 (22.9)	4 (0.9)
	medicine Managerial job		286 (35.9) 294 (17.2)	0 (0.0)
	Yes Unemployed	1	1 137 (17.2) 204 (12.0)	1 22 (5.0)
	No Pensioner	1.39 1.04-1.86 0.026 0.98 0.54-1.78 1.54 1.10-2.14 3 (0.4) 801 (46.9) (92.3)
	Contextual factors Missing		8 (0.9)	18 (1.0)	7 (1.8)
	Indicator of potential Perceived financial status					<0.001
	access to general Comfortable/Things are good	352 (44.2) 840 (49.2) (50.2)
	Tight/I have to be careful		295 (37.0) 594 (34.8) (36.9)

a 462 Boldface indicates statistical significance (p≤0.05).

Funding

Adeline Monet was supported by the French League Against Cancer (La Ligue Nationale contre le Cancer). The VICAN study was funded by the French National Institute of Cancer (Institut National du Cancer, INCa) (Contrat de recherche et développement n°05-2011).

Compliance with Ethical Standards

Conflict of interest statement:

No conflict of interest was reported by the authors of this paper.

Role of funding


Le Lay Y.-F.1 et Piégay H. 1 , 2005. Role of knowledge and cultural variations in public perception of riverscapes with and without wood. Communication orale pour l'International Sociology Conference "Environment, knowledge and democracy" organisée à Marseille les 6 et 7 juillet.

Problem statement and hypothesis

During the First International Conference on Wood in World Rivers, held in Oregon (U.S.A.) in October 2000, participants indicated that strong regional contrasts appear in the appraisal of riverscape quality, particularly in the perception of large wood (LW) deposited in the channels [START_REF] Gregory | The Ecology and Management of Wood in World Rivers[END_REF]. Over the last three decades, there has been an increasing scientific interest in LW and scientists have recognised the hydraulic, geomorphic and biological role of wood in temperate river systems [START_REF] Triska | Role of wood debris in modifying channel morphology and riparian areas of a large lowland river under pristine conditions: a historical case study[END_REF][START_REF] Sedell | What we know about large trees that fall into streams and rivers[END_REF]. Although LW re-introduction has been promoted in different areas, such as in North America, Australia, Switzerland or Germany, such measures are not accepted by managers and users in other countries [START_REF] Boyer | Guide Technique SDAGE -La Gestion des Boisements de Rivière: Dynamique et Fonctions de la Ripisylve[END_REF][START_REF] Reich | Totholz in Fliessgewässern -Empfehlungen zur Gewässerentwicklung[END_REF]. In order to understand the reasons for some spatial variations in LW public perception amongst different geographic areas in the world and notably in Europe, we have analysed the social, cultural and historical context of the question. One of our aims, described in this contribution, was to evaluate the visual and emotional impact of riverscape on the motivation to improve streams and rivers.

Material and methods

The survey is based on a questionnaire and a set of 20 photographs, which represent watercourses running through various physical and humanised environments. Half of the scenes are characterised by river and stream sections obstructed by wood while the 10 others are free-flowing, without LW. To evaluate the overall scenic attractiveness of each picture, respondents rated four perceived values of the 20 colour photographs (namely aesthetics, naturalness, danger, and need for improvement) on Visual Analog Scales ranging from 0 to 10 [START_REF] Gift | Visual analog scales: measurement of subjective phenomenon[END_REF]. The questionnaire included also two qualitative variables for characterizing the perception of danger and the motivation for improving riverscapes. The study was performed using the same protocol in eleven geographical areas (France, Poland, Sweden, India, Russia, Germany, Italy, Spain, China, Oregon (U.S.), Texas (U.S.)), which have been selected because they reflect a potential diversity of socio-cultural environments. With a low variability in age classes, the student community is a very interesting experimental population for international comparisons and students' responses were presumed to represent knowledge of non expert groups [START_REF] Brown | Landscape aesthetics of riparian environments: relationship of flow quantity to scenic quality along a wild and scenic river[END_REF]. Similar disciplines were surveyed in each of the areas concerned. More information about methodological aspects is presented in Piégay et al. (in press).

Social acceptance of in-channel wood

The results show that the presence of in-channel LW modifies students' perceptions (Figure 1a). The respondents considered riverscapes with LW to be less aesthetically pleasing, more natural, more dangerous, and needing more improvement than those without LW. When considering the perceived danger (Figure 1b), the participants evaluate the scenes with wood as being more dangerous in terms of water quality and affecting leisure activities. Moreover, the students consider that the riverscapes without LW require much more improvement than those without (Figure 1c). With LW presence, there is an increase in the perceived need for cleaning the channel and improving the landscape quality.

The results highlight a negative perception of LW by respondents which influences their attitudes towards river management [START_REF] Gregory | The perception of riverscape aesthetics: an example from two Hampshire rivers[END_REF]. Some archetypes affect the valorisation of landscape scenes, making clean water the vital fluid, the nurturer of life, and the pre-eminently pure element where LW evoke the human death and seems to be an intolerable body polluting the maternal and divine element (Bachelard, 1942;[START_REF] Durand | Les structures anthropologiques de l'imaginaire (Introduction à l'archétypologie générale[END_REF].

A cultural cross-view for wood management in watercourses

The comparative geographical analysis demonstrates some substantial cultural differences amongst the geographical areas (Figure 2a). Particularly, Asian students show a great motivation for improving watercourses, whereas respondents from other countries (German, Oregon, or Sweden) show a more conservationist attitude towards streams and rivers.

Many factors can explain the geographical variability. For instance, the motivation for improvement (Figure 2b) seems to vary according to the familiarity with LW, the combination of forest cover and density of population, the history of land uses (agricultural tradition in Western Europe or forestry in Oregon and Sweden), the technocratic management of watercourses (France and Russia) and the necessity of development (China and India).

Conclusion

Public awareness of environment has increased very significantly in the most developed countries since the last decades. Nevertheless, values, feelings and beliefs may trigger the decision-making of LW removal throughout the world. Modified channels appear to be those that are most acceptable to the public. The consequences of the negative perception of LW may explain why wood reintroduction in streams and rivers is still infrequent, even as an experimental stream restoration technique.

These results raise the question as to whether the management of riverine landscapes should acknowledge the commonly-held national perception of riverscape. There is a need to develop a greater appreciation of LW-rich channels that are scientifically and ecologically important, through environmental education that should be considered for river restoration purposes. A complementary study involving French river management officials is in process, in order to establish how knowledge influences the LW perception regarding landscape and risk occurring in watercourses.

Acknowledgement

These results have been provided from a survey developed by an international working group leaded by H. Piégay (CNRS, France) and K. J. Gregory (Univ. Southampton, U. K.) and composed of V. Bondarev (Moscow State Univ., Russia), A. Chin (Texas A & M Univ., USA), N. Dalhstrom (Mid Sweden Univ., Sweden), A. Elosegi (Univ. of the Basque Country, Spain), S.V. Gregory (Oregon State Univ., USA), V. Joshi (S.P. College, Pune, India), M. Mutz (Brandenburg Technological Univ. Cottbus, Germany), M. Rinaldi (Univ. of Florence, Italy) B. Wyzga (Polish Academy of Science, Krakow, Poland) and J. Zawiejska (Jagiellonian Univ. Poland). We thank C. Arrese-Igor, I.P. Balabina, K.G. Bondareva, D. Borchhardt, T.A.

  Budykina, B. Chocat, S. Dufour, F.Y. Dzerzhinskiy, L. Erriondo, K. Forest, J. Given, B. Gumiero, C. Jackson, P. Joly, V. Kale, J. Kippenberger, L. Kshirsagar, J. Lach, R. Loire, C. Montoya, O. Ormaetxea, S. Painter, A.A. Protsenko, A. Radecki-Pawlik, M. Reich, A.I. Stifeyev, N.E. Voinova, L. Wang, and N.A. Yasamanov for helping during the survey process and data downloading and validation. The authors thank also the European Community (Life Program "Forests for Water" 2003-2007) for providing funding to review the interest of forest for improving the water management, preserving the water and water ecosystem quality.

Figure 1

 1 Figure 1 (a) Wood in rivers, a negatively perceived object. The grey boxplots represent the values assigned to the riverscapes without wood and the black boxplots represent the values assigned to the riverscapes with wood. (b) The percentage for each danger type rated by students from 20 riverscapes with and without wood. (c) The percentage for each improvement type rated by students from 20 riverscapes with and without wood.

Figure 2

 2 Figure 2 (a) Segment diagrams. Each diagram represents one geographical area. On each of them, four continuous variables (scores for aesthetics, naturalness, feeling of danger and need for improvement) are plotted by a radius whose length corresponds to the mean value attributed by the students of the given area. (b) Dendrogram. A hierarchical cluster analysis has been performed on the mean values of need for improvement (provided by students from 11 geographical areas who scored the 20 riverscapes).

Université de Lyon, CNRS-UMR 5600 "Environnement, Ville, Société", 18 rue Chevreul 69362 Lyon Cedex 7, email : yf_lelay@hotmail.com