Stefano Farolfi
email: stefano.farolfi@cirad.fr

Sylvie Morardet

Faten Khamassi

Marc Willinger

Farmers' perceptions of water management in Jemna oasis, Southern Tunisia

Keywords: Farmers' perceptions, Institutions, Oasis, Public organisations, Rules, Tunisia, Water management

Groundwater resources are a crucial driver of development. Since the 1970s, the expansion of irrigated land on the margins of the existing 'traditional' oases has been encouraged by the Tunisian authorities to enhance local development. As a result, oases in Southern Tunisia are currently facing sustainability concerns. This situation requires alternative water management approaches, in which local actors collaborate and contribute to the design of new rules. To understand Tunisian oasis farmers' perceptions of water rules and public organisations, in 2021, we conducted an online survey in Jemna, an oasis in the Kebili region in Southern Tunisia. The picture that emerged from the online survey is that farmers in extension areas have distinctive characteristics but also similarities with farmers in the traditional oasis. Both types of farmers mainly cultivate date palm (monoculture), and, like farmers in the extensions, many farmers in the traditional oasis have a private borehole. All farmers in the Jemna oasis clearly perceive the limited availability and poor quality of the groundwater resource. However, they do not believe these problems cause conflict among farmers. They consider that, to solve possible conflicts and to ensure better water management in the oasis, collaboration among farmers is more effective than changes to rules issued by existing organisations. These preliminary results, if confirmed, can have important policy implications, as the farmers' perceptions of water rules and organisations, as well as farmers' willingness to collaborate, are crucial for a possible new approach to water management in the oasis.

Introduction and rationale

Today, groundwater resources are a crucial driver of development [START_REF] Shah | Taming the anarchy: groundwater governance in South Asia. Resources for the Future[END_REF][START_REF] Shah | Groundwater: a global assessment of scale a-nd significance[END_REF]. A large proportion of food production systems and consequently food security, depend on them. Groundwater exploitation has enabled improvement of local living conditions in many arid and semi-arid areas around the world, but also promoted agricultural practices that require irrigation [START_REF] Changming | Groundwater exploitation and its impact on the environment in the North China Plain[END_REF][START_REF] Konikow | Groundwater depletion: a global problem[END_REF][START_REF] Ross | The challenge of groundwater governance: case studies from Spain and Australia[END_REF].

The intensification of irrigated agriculture, fostered by policies aimed at improving local livelihoods, led to the emergence of what is called the 'groundwater economy' [START_REF] Kuper | Liberation or anarchy? The Janus nature of groundwater use on North Africa's new irrigation frontiers[END_REF][START_REF] Amichi | Des serres et des hommes : des exploitations motrices de l'expansion territoriale et de l'ascension socioprofessionnelle sur un front pionnier de l'agriculture saharienne en Algérie[END_REF]. Recent trends are now jeopardizing groundwater resources in many areas, lead-ing several authors to talk about the 'collapse' of some groundwater economies [START_REF] Petit | Can agricultural groundwater economies collapse? An inquiry into the pathways of four groundwater economies under threat[END_REF].

Groundwater is an example of a Common Pool Resource (CPR) [START_REF] Ostrom | Governing the commons: the evolution of institutions for collective action: The Political economy of institutions and decisions[END_REF], which need appropriate local policies and rules to avoid overexploitation and depletion, that can be irreversible and ultimately cause the collapse of the entire system.

Oases are 'exceptional entities' [START_REF] Fassi | Les oasis du monde : Carrefour des civilisations et chantier universel pour le développement durable[END_REF] where groundwater availability and peculiar ecological conditions are met, which allow humans to live and practice agriculture in very arid zones, such as deserts. In the past, oases have proven their ability to adapt and shown their resilience in the face of harsh conditions [START_REF] Fargette | Modélisation pour la détection de types de pratiques agricoles oasiennes : cas de l'oasis de Nefta dans le Djérid tunisien[END_REF]. Their role in the development and management of arid zones is widely recognized [START_REF] Kassah | Oasis et aménagement en zones arides. Enjeux, défis et stratégies[END_REF]. At the same time, maintaining the delicate balance among the different components of these fragile socio-ecosystems requires integrated management of the resources, including groundwater, to ensure sustainable development [START_REF] Fassi | Les oasis du monde : Carrefour des civilisations et chantier universel pour le développement durable[END_REF].

Recent studies [START_REF] Trigui | Implication of hydrogeological and hydrodynamic setting of water quality in the Complex Terminal Aquifer in Kebili (southern Tunisia): The use of geochemical indicators and modelling[END_REF] show the growing stress to which the complex terminal aquifer in Kebili, Southern Tunisia, is subject. This stress is mainly due to demographic and agricultural developments. According to the authors, since the 1950s, the region has experienced a perpetual evolution of the number of deep boreholes exploiting the aquifer to meet the growing water needs. The growth of domestic and productive water uses "has caused a considerable intensification of water exploitation which rose from 47.40x10 6 m 3 in 1950 to 297.77x10 6 m 3 in 2015. […] The excessive increase of exploitation resulted in a change of the hydrodynamics of the aquifer" [START_REF] Trigui | Implication of hydrogeological and hydrodynamic setting of water quality in the Complex Terminal Aquifer in Kebili (southern Tunisia): The use of geochemical indicators and modelling[END_REF].

The oases in Southern Tunisia have a very long history. In the distant past, access to water resources was collective [START_REF] Mekki | Management of groundwater resources in relation to oasis sustainability: The case of the Nefzawa region in Tunisia[END_REF] and free of charge. Traditional community level assemblies defined management rules and resolved conflicts. In 1885, the Tunisian government appropriated springs and became the sole owner of oasis zones [START_REF] Attia | Étatisation de l'eau dans les oasis du Jérid tunisien. Lecture d'une dépossession[END_REF]. In the past half century, the Tunisian government has implemented a variety of policies to in-centivize local development through more intensive use of natural resources [START_REF] Attia | Étatisation de l'eau dans les oasis du Jérid tunisien. Lecture d'une dépossession[END_REF]. The land reform between 1964 and 1969 imposed collectivist organisation, and the 1975 water code completed the transfer of water ownership to the State [START_REF] Brochier-Puig | Water uses in oases under urbanization process: the case study of Nefzawa in southern Tunisia. Transforming territories[END_REF]). In addition, in the last 50 years, water users associations were created and progressively started to collaborate with regional organisations, named CRDA (French acronym for the Regional Agricultural Development Commission) [START_REF] Mekki | Management of groundwater resources in relation to oasis sustainability: The case of the Nefzawa region in Tunisia[END_REF]. Water users associations, today called GDA (French acronym for Agricultural Development Groups), originally functioned under public directives and control, but underwent several changes in status and in their mandates over time. In particular, there was a progressive transfer of responsibilities to farmers and increased involvement of the members of water users associations in collective water management.

Many GDA experienced from the beginning a number of problems, such as the lack of acknowledgment by the member farmers of the GDA water management capacity [START_REF] Farolfi | Information provision and willingness to pay irrigation water in Tunisian local associations for agricultural development. An experimental economics study[END_REF]. Farmers consider often GDA as a simple tax collector. This resulted in weak commitment by member farmers in the functioning of the organisation, and often in their unwillingness to contribute financially to it through the payment of water fees. As a consequence, many GDA face today serious financial problems and cannot implement properly water management actions. Moreover, a recent study [START_REF] Mahdhi | Water users associations and irrigation water use efficiency in coastal oases areas in Gabès, southeastern Tunisia[END_REF], points out the inefficiency of GDA in Tunisia, resulting from both management and engineering factors.

Since the 1970s, the expansion of irrigated land on the margins of the existing 'traditional' oases has been encouraged by Tunisian authorities in order to enhance local development, particularly the production of the internationally renowned Deglet Noor date, the main local product [START_REF] Ghazouani | Farmers' Perceptions and Engineering Approach in the Modernization of a Community-Managed Irrigation Scheme. A Case Study from an Oasis of the Nefzawa (South of Tunisia)[END_REF]. However, expansion exceeded the government's expectations through the digging of 'illicit' boreholes by private farmers, and to continued planting of increasing numbers of date palms. As a result, oases in Southern Tunisia are currently facing sustainability concerns due to "uncontrolled expansion of irrigated areas, overexploitation and degradation of groundwater resources, and soil degradation" [START_REF] Ghazouani | Farmers' Perceptions and Engineering Approach in the Modernization of a Community-Managed Irrigation Scheme. A Case Study from an Oasis of the Nefzawa (South of Tunisia)[END_REF][START_REF] Mekki | Management of groundwater resources in relation to oasis sustainability: The case of the Nefzawa region in Tunisia[END_REF].

This situation raises a number of questions. How should public policies be revised to tackle overexploitation of oases in Southern Tunisia [START_REF] Mekki | Management of groundwater resources in relation to oasis sustainability: The case of the Nefzawa region in Tunisia[END_REF]? Are GDAs the appropriate entity to manage groundwater resources? Can alternative management approaches, as proposed by [START_REF] Petit | Can agricultural groundwater economies collapse? An inquiry into the pathways of four groundwater economies under threat[END_REF], improve local groundwater management? And particularly, is there a potential for endogenous governance systems [START_REF] Ostrom | Governing the commons: the evolution of institutions for collective action: The Political economy of institutions and decisions[END_REF]), e.g. the establishment of rules and institutions emerging through the water users' cooperation, that could complement the public sector's water management framework?

To assess the potential for introducing new water management pathways in Tunisian oases, we have to understand farmers' perceptions of and attitudes to existing water management systems, rules and public organisations,1 their willingness to cooperate as well as their attitudes to other farmers' practices and water uses. The exploratory nature of this work did not call for an attempt to deeply understand the current formal and informal rules. The goal was rather to get a rapid assessment of local farmers' views on the GDA institutional setting, ask whether or not they consider it appropriate for local water management, and whether arrangements among farmers can be useful.

Hence, the objective of this study, undertaken in the framework of the IDES research project2 is twofold. The first aim was to identify the profile of farmers who have plots in both traditional and extension areas of a typical Tunisian oasis,3 to check for possible differences in the farming models, and consequently, in water uses, in the two zones. The second aim was to understand farmers' perceptions of water problems and possible remedies, to under-stand whether there is room in Tunisian oases for new water management approaches originating from cooperation between farmers and the co-construction of rules.

To achieve these aims, in 2021, we conducted an online survey of 65 farmers in both the traditional oasis and extensions in Jemna oasis, Kebili region, Southern Tunisia. Information was collected on farm structure and dynamics, water uses, the farmers' perceptions of water governance rules and organisations, and analysed to understand the attitudes of local farmers towards the current water management system, and their potential willingness to change to more appropriate local water policies.

The survey results showed that farmers with plots located in extension areas have distinctive characteristics but also share similarities with the farmers with plots located exclusively inside the traditional oasis. All the farmers in Jemna oasis clearly perceive the limited availability and poor quality of the groundwater. However, they do not believe that these problems are at the source of conflicts among farmers. They consider that potential future conflicts can be solved more effectively through farmers' informal collaboration than by new rules imposed by existing organisations. Farmers in Jemna oasis are willing to collaborate with other farmers, and have more confidence in collaboration among themselves than they have in the public organisations when it comes to identifying more effective and sustainable water management in the oasis.

The remainder of the paper is organized as follows. In section 2, we describe the study area and the methods used to collect and process the data. In section 3 we present the results of the survey and the estimates of a probit model. In section 4, we discuss our findings and their implications in terms of pathways for new groundwater governance tools and methods in Tunisian oases.

Materials and methods

The study area

Jemna oasis is situated in the Governorate of Kebili, Southern Tunisia (33.30°-34.15°N; 8.30°-9.10°E). It is formed of two urban sectors, North Jemna and South Jemna, located in the South Kebili delegation, which occupies an area of 1,182 Km 2 (5.26% of the Kebili Governorate) and has 32,270 inhabitants (INS, 2018) (Figure 1).

Nine water users' associations (GDA) exist in the oasis. They account for an irrigated area of 747 Ha, and 1,727 member farmers (data provided by the local farmers' association for the development of Jemna oasis and obtained in a study conducted in 2021 as part of the IDES project). Farmers who belong to water users' associations get their water from collective boreholes through a collective distribution system based on water delivery turns, and pay a fee to the GDA for access to water. The GDAs manage the irrigated areas in the 'traditional oasis'. Outside the traditional oasis, new farms have more recently been established and occupy the land at the margins of the existing farms. These farmers get their irrigation water from private boreholes that are not declared to the regional water management authority (CRDA). These farms correspond to what we term 'extensions'. Due to the rapid development of these farms, and to the informal nature of the arrangements underpinning this irrigated land, it is impossible to obtain accurate information on their number and size. The local farmers' association for the development of the Jemna oasis estimated that about 900 farmers only cultivate plots in the extensions of the Jemna oasis. Many farmers who belong to the GDA farm plots in both the traditional oasis and the extensions. In the remainder of the paper, these farmers are referred to as "mixed farmers", while farmers who have plots only in the traditional oasis are referred to as "GDA farmers", and those who have plots only in the extension are referred to as "extension farmers". The first two groups are both members of the GDA.

Like the other oases in the Kebili Governorate, the main product cultivated in Jemna oasis is dates. Monoculture is dominant, but 2-layer (palms and fruit trees) and 3-layer (palms, fruit trees and vegetables) cropping systems are also present.

Survey and data analysis

Due to Covid-19 pandemic constraints, we had to conduct our survey online instead of the originally planned face-to-face survey. A total of 65 farmers, identified through the local farmers' association for the development of the Jemna oasis, responded to an online ques- tionnaire directly on their smartphone. The two criteria of selection for our non-stratified sample were to be located in the Jemna oasis and to be able to answer an online survey. The latter criterion influenced particularly the process of sample selection. A list of 89 farmers was provided to the research team, who contacted all of them. 13 farmers did not agree to participate in the survey (rate of rejection of 15%). Additionally, 11 farmers who only had a simple mobile phone could not participate in the survey. This left the team with 65 respondents. 4 Our sample was not built following a randomized or a systematic process. It was rather based on an available and readyto-use database of farmers. For this reason, our results cannot be considered unbiased and definitive, but rather a first picture from which we can implement further studies.

The 65 respondents of our sample cultivate a total area of 122 ha and represent 2.5% of the total number of farmers in the oasis and 2.6% of the estimated total cultivated area. 5 Out of the 65 interviewed farmers, 24 only cultivated plots in the traditional oasis ("GDA farmers"), 31 cultivated plots in both the traditional oasis and the extensions ("mixed farmers"), and 10 only farmed plots in extension areas ("extension farmers").

The questionnaire 6 was in Tunisian Arabic and contained 50 closed questions and one open question, the latter was not used in this analysis. The questionnaire was organised in 4 Using the formula to calculate the size of the sample in a population where the proportion of the character to estimate is unknown (p=0.5), our sample (65 subjects) would allow to estimate the proportion at a confidence level of 95% with a 12% margin of error. 5 To estimate the irrigated area in the extensions, we first multiplied the average area farmed by the extension farmers included in our survey (2.5 ha) by the total number of farmers located in the extension areas (900) previously assessed by the association for the protection of the Jemna oasis. This corresponds to an area of 2,250 ha. In the absence of precise data on farm structure in the area, we use information collected through local surveys and interviews to hypothesise that half the farmers who farmed plots in the traditional oasis (GDA members) also farmed plots in the extensions. This corresponded to 863 farmers (rounded to the nearest integer). We estimated that the average size of the plots in the extensions cultivated by mixed farmers was 1.97 ha = 2.4 ha (average size in our survey of a farmer with plots in both areas) -0.43 ha (average size of plots in GDA according to an IDES study currently underway in Jemna). We then multiplied the two terms (863 x 1.97 ha) to obtain the area cultivated in the extensions by GDA members = 1,700 ha. By summing the two above areas, we obtained the total area in the extensions of 2,250 ha + 1,700 ha = 3,950 ha. This area was then added to the cultivated surface area in the nine GDA (747 ha) giving a total estimated area cultivated in Jemna of 4,697 ha. 6 Available online in French and in Arabic at: https://newmedit.iamb.it/bup/wp-content/uploads/2022/07/Questionnaire-Jemna.pdf .

sections around the following topics: general data (membership of the GDA, location of the plots in the oasis, etc.), cropping system, water use and irrigation system, demographic and socio-economic data, and the respondent's perception of the rules, organisations, and governance system of the oasis.

To help us understand the farmers' perceptions of and attitudes to water management in the Jemna oasis, the second part of the questionnaire contained a series of multiple choice statements to which respondents had to answer by choosing one of the following: 1 = I strongly disagree; 2 = I disagree; 3 = I agree; 4 = I strongly agree, corresponding to a four-level Likert scale. We chose to not have a 5-level scale in order to avoid a central tendency bias.

The investigator first contacted each respondent by telephone, and invited him (all the respondents were male) to use his mobile phone or computer to open a dedicated link on a server (Heroku) to complete the questionnaire. After checking the answers, the investigator again contacted each respondent to check the accuracy of the data, correct possible anomalies in the information provided and remove aberrant data.

Anonymity of the data was ensured by a protocol validated by CIRAD personal data protection system, which is based on the European general regulation on personal data protection (Regulation EU 2016/679). The survey was also declared to the Tunisian National Authority for the Protection of Personal Data (INPDP).

The database resulting from the survey contains 63 variables and 65 observations.

Statistics and tests of significance were conducted to describe the characteristics of the sample and the farmers' attitudes to water management. We then used a probit model [START_REF] Gujarati | Basic econometrics[END_REF] to analyse the behaviour of a dichotomous dependent variable (farming plots only inside the traditional oasis vs outside 7 ). Probit models make it possible to perform regressions with binary dependent variables i.e. dependent variables that are coded "0-1". These models provide an estimate of the probability that the dependent variable takes the value 1. Probit analyses usually require larger samples to be meaningful. However, given the exploratory nature of our study, we considered appropriate to use this econometric method in this case.

Results

We split the sample into three groups that emerged from the survey: 1) farmers who only had plots inside the traditional oasis ("GDA farmers"), 2) farmers who only had plots in the extension areas ("extension farmers"), and 3) farmers who had plots in both zones ("mixed farmers").

Population, agricultural production and water use in the traditional oasis and in the extensions

All the farmers interviewed were men, which is the usual situation in Tunisia. GDA farmers were on average 10 years older than the farmers in the two other groups, their farms are smaller 7 In other words, "GDA farmers" vs the combination of "mixed farmers" and "extension farmers".

(less than ½ the size of the farms in the other groups), and they began farming more than 10 years earlier (Table 1).

Age was an important factor affecting the willingness of farmers to invest and innovate. Only 17% of GDA farmers were willing to buy an additional plot of land. The proportion rose to 40% for extension farmers and to 61% for mixed farmers. A chi2 test on the frequency distributions showed that the difference between the three groups was significant (p value = 0.005).

All the extension farmers we surveyed declared that agriculture was their main activity. In contrast, 21% of the GDA farmers and 32% of mixed farmers declared that agriculture was not their main activity. In the latter two cases, farmers whose main activity was not agriculture worked in public administration. The educational level of extension farmers and mixed farmers was higher, respectively 30% and 26% had a secondary school leaving certificate, whereas only one surveyed farmer among GDA-farmers had a secondary education. In contrast, none of the extension farmers had received practical agricultural training, whereas 26% of mixed farmers and 33% of GDA farmers had.

The main production system in both the traditional oasis and the extensions is date palm monoculture. Our results suggest that two or three layer production systems that were still present in the traditional oasis a decade ago [START_REF] Mekki | Management of groundwater resources in relation to oasis sustainability: The case of the Nefzawa region in Tunisia[END_REF] are now disappearing rapidly, and that farmers in the extensions only grow date palms in simplified cropping systems. According to the survey, 80% of the production systems of extension farmers are date palm monoculture, versus 71% for GDA This could be due to the unwillingness to declare 'illegal' activities in an online survey. Mixed farmers may also irrigate their plots in the extension with water from the collective network, if these plots are close to the traditional oasis. The picture that emerged from the survey in terms of water extraction shows a diffused practice of digging private boreholes, mainly in the extensions, but also in the traditional oasis.

Table 2 summarizes some statistics concerning boreholes. The average depth of boreholes is considerably deeper in the extensions, while the date of drilling is very similar for all types of farmers.

Solar pumps are the most popular way of extracting water used by the farmers (44.4% of extension farmers, 62.5% of GDA farmers, and 71.4% of mixed farmers, based on our surveyed sample). These systems are certainly less expensive in terms of energy, and were subsidized through public policy initiatives in recent decades. Both inside the oasis and in the extension areas, non-solar electrical pumps are preferred 8 Conversion rate for DNT to Euro is 0.306. to diesel pumps for their higher power (33.3%, 12.5% and 23.8% by GDA farmers, extension farmers, and mixed farmers, respectively).

Irrigation systems differ significantly in the three groups of farms (chi square p-value = 0.000 based on the distribution frequency of the following systems: drip irrigation, sprinkler irrigation, flooding, and mixed systems). In extension areas, the most popular technique is drip irrigation (60% of the farmers in this zone used drip irrigation), while, as expected, in the traditional oasis, it is flooding (79.1%). Almost half (48.9%) the mixed farmers used more than one technique and that sprinkler irrigation was only used in the traditional oasis (12.5% of the GDA farmers' surveyed used sprinklers).

Farmers who are members of GDAs pay for their water which is available through the collective water distribution system and is based on water delivery turns. The fee paid by to the GDA by farmers in the region ranges from 650 DNT 8 /ha/year to 1,500 DNT/ha/year. The farmers surveyed in Jemna paid an average of 93.5 DNT/month to the GDA. These farmers said the time between two water turns was more than 12 days. The duration of the irrigation turn is between 7 hours (GDA farmers) and 10 hours (mixed farmers) depending on the GDA. According to the CRDA, the average water flow is 20 l/s, but is subject to variations from case to case. The majority of farmers were not satisfied with either the frequency or the length of the delivery turn (only 12% of GDA farmers and 30% of mixed farmers were satisfied), and 60% of GDA farmers and 92% of mixed farmers would be willing to pay more for a more frequent and longer delivery turn.

Farmers' perceptions of water management in the oasis

The first two sentences concerning the farmers' perceptions of water management only addressed farmers who were members of a GDA (i.e. GDA farmers and mixed farmers). The sentences were: "I am satisfied with the GDA's water management in the oasis" and "current GDA rules are sufficient to guarantee enough water for everyone at the right price".

Time between two turns (days)

Hours/turn Satisfied with turn (% of yes)

Willing to pay for better turn (% of yes)

GDA farmers >12 6.9 10% 60%

Mixed farmers The bar graph in Figure 2 shows the average choices of the surveyed farmers who are members of a GDA on a 1-4 scale. The overall perception of farmers of GDA water management and rules was poor (average = 2.11 and 1.77, respectively). This result is in line with the results obtained by [START_REF] Farolfi | Information provision and willingness to pay irrigation water in Tunisian local associations for agricultural development. An experimental economics study[END_REF] who reported farmers did not recognize the role of the GDA in Tunisia.

The second group of sentences concerned the farmers' perception of water availability ("There is enough water for everyone in Jemna oasis"), access to water ("In addition to being available, water is accessible to everyone in Jemna oasis"), and water quality ("I am satisfied with the quality of the water in the oasis").

The bar graph in Figure 3 shows that the farmers' perception of water quality, availability and access in the Jemna oasis is quite poor (average = 1.93, 1.74, and 1.68, respectively, for quality, availability and access, when all respondents are considered). The perception is the same for the farmers in the three groups (Kruskal-Wallis test, p-value = 0.902, 0.597, 0.689, respectively, for quality, availability and access), and consequently both in the traditional oasis and in extensions. Complementary qualitative interviews to understand why people in Jemna consider that there is not enough water (e.g.: decrease of water flows in GDAs, decrease of groundwater levels and flow in extensions, etc.) would have been useful. They are foreseen in a future work.

The third group of sentences concerned conflicts about water in the Jemna oasis. First, the farmers read the following sentence: "There are conflicts concerning water in Jemna oasis". Figure 4 shows that farmers in the Jemna oasis do not consider conflicts over water to be serious (average = 2.00, 1.93, and 1.72 respectively for extension farmers, mixed farmers and GDA farmers). Although the perception of conflict by GDA farmers was lower than in the other groups, the Kruskal-Wallis test shows that the difference between groups is not significant (p-value = 0.556). In other words, farmers in the Jemna oasis are perfectly aware of water scarcity and the fact that water availability and access are not sufficient, but they consider that this scarcity is not a source of conflict among water users. Farmers then had to react to two sentences about how to solve conflicts over water in the oasis. The first sentence was "Water conflicts can be solved through better management rules" and the second was "Water conflicts can be solved if farmers collaborate". When reacting to these sentences, GDA farmers may refer to conflicts about water turns and possible water stealing or no respect of rules in the GDA, while extension farmers may refer to conflicts arising from land appropriation or discussions about farm borders.

The bar graph in Figure 5 shows that farmers gave a higher score to collaboration among themselves than to better management rules in resolving conflicts over water in the oasis (average = 3.08 and 2.77 respectively, when all respondents are considered). A Mann-Whitney test on the whole sample indicated this difference is significant (p-value = 0.045). Extension-farmers had a higher perception of the two means of conflict resolution than farmers in the other two groups (although the Kruskal-Wallis test was not significant: p-value = 0.521 and 0.257, respectively, for rules and collaboration). However, all the groups of farmers scored collaboration among themselves higher than better management rules.

The two next sentences concerned the farmers' willingness to collaborate with other farmers to manage water: "I am ready to collaborate with the other farmers for better water management" and "I know other farmers who would be willing to collaborate for better water management".

The bar graph in Figure 6 shows that farmers in the Jemna oasis are willing to collaborate and know other farmers who are equally willing to collaborate with them (average = 3.31 and 3.17 respectively, when all respondents are considered). This is equally true for all three groups of farmers (the Kruskal-Wallis test was not significant: p-value = 0.136 and 0.622, respectively, for readiness to collaborate and knowing other farmers willing to collaborate, and the average answers are all above 3).

Finally, the two last sentences concerned the farmers' trust in public organisations and in collaboration with other farmers "I trust collaboration among farmers for water management" and 9 The term 'institutions' was used in the survey.

"I trust public organisations 9 for equitable water management".

The bar graph in Figure 7 shows a clear difference in favour of farmers' trust in collaboration among themselves for water management rather than trust in public organisations (average = 3.12 and 2.21 respectively, when all respondents are considered). A Mann-Whitney test on the whole sample indicates that this difference is significant (p-value = 0.000).

This difference is present in all groups of farmers with no significant variability between groups (the Kruskal-Wallis test was not significant: p-value = 0.569 and 0.907 respectively for trust in others and in public organisations).

Discriminating characteristics of farmers who cultivate land in the traditional oasis and in the extensions

The descriptive analysis reported in the previous section clearly revealed significant differences among the three groups of farmers in the Jemna oasis both in socio-economic characteristics, perceptions of and attitudes to water management.

The objective of this section is to identify the variables that distinguish farmers who only cultivate land inside the traditional oasis (GDA farmers) and farmers who have all or some of their plots in extension areas. In the latter group, we include both farmers who only have plots in extensions (extension farmers) and farmer who have plots in both areas (mixed farmers). 10 To apply the probit model presented in the materials and methods section to this sample, we defined the dependent variable as a dichotomous variable taking the value of 1 when farmers only have plots in the traditional oasis, and the value of 0 in all other cases. The explanatory variables chosen for the probit model were based on the descriptive analysis presented in the previous sections. We selected some of the demographic, socioeconomic and behavioural variables that revealed significant differences between the groups of farmers. These variables are the age of the head of the household (numerical), the education level of the head of the household (1,2,3 for the three levels "primary", "secondary", and "higher"), surface area of agricultural land (numerical), presence of a borehole (0 for "no" and 1 for "yes"), willingness to buy additional land (0 for "no" and 1 "yes"), year of start of farming activity (numerical), production system (two variables coded 0 for "monoculture" and 1 for "2 layer" or "3 layer systems") , member of the local farmers' association for the development of the Jemna oasis (0 for "no" and 1 for "yes"), farming is their main activity (0 for "no" and 1 for "yes"), and variables concerning the percep- 10 We did so having in mind a broader empirical model of water extraction (see recommendations for future research below). If unobserved variables determine both the probability of having plots only in extension areas and water extraction, then a two-step procedure is needed [START_REF] Heckman | Sample selection bias as a specification error[END_REF]. The first stage of the Heckman procedure is a probit model. tion of conflicts over water and access to water (1,2,3,4 according to the Likert scale). As all the farmers interviewed were men, the variable "gender" was not included.

Table 4 shows the average marginal effects of a probit model using different specifications. The specifications in the first two columns focus on the role of farmers' characteristics, while the specifications in the last three columns show the importance of farmers' perception of conflicts about water, and how to resolve them. More precisely, the first column underlines the role of farming characteristics; the second column adds the household head's characteristics; the third column shows the same specifications but using a reduced dataset so as to properly compare these coefficients with the following ones; the fourth column adds two variables about farmers' perception of conflicts and access to water. Finally, the last column adds a variable on the farmers' perception of cooperation as a way to solve water conflicts.

Over 65 observations, one observation was missing for willingness to buy additional land and three were missing for the year the farming activity started. Consequently, only 61 observations were used in the first column. Despite choosing perception variables with the least missing values, the sample in the third column was reduced to the 53 observations available for conflict perception variables. In fact, eight more observations were lost when perception variables were added in the fourth and fifth columns.

We first observed that the variables willingness to buy additional land and year of farming activity started were negatively and significantly correlated with the probability of only having plots inside the traditional oasis. When willingness to buy additional land moved from 0 to 1, it reduced the probability (0-1) of only having plots in the traditional oasis by about 0.2. Willingness to buy additional land is an important factor for a farmer to have a plot in the extensions, whatever the specification considered. The effect of the year the farming activity started on the absence of plots in the extensions was small but significant, regardless of the specification considered. However, it was negative, showing that farmers who had plots in extension areas started agricultural activities later than GDA farm-ers. Farm area was negatively correlated with the group of GDA member farmers, indicating that farms in this group are significantly smaller than farms with plots in the extensions. We observed no effect of the cropping system (date palm monoculture versus the two mixed 2-layer and 3-layer cropping systems) nor of the presence of a borehole. These results are in line with descriptive statistics underlining the similarity of the cropping system (monoculture) in the two zones, and a tendency to drill boreholes not only in the extension areas, where no water is supplied by the GDA, but also within the traditional oasis. Farming appeared to be more often the main activity of GDA farmers than of extension or mixed farmers, as the estimation coefficient was positive and significant. However, it should be noted that this coefficient was not robust to all specifications. In fact, looking at the descriptive statistics in the previous sections, while the main activity of all extension farmers was agriculture, this was only true of 68% of mixed farmers and of 79% of GDA farmers. As expected, being a member of an association was positively correlated with farmers who only farmed plots in the traditional oasis. When association membership moved from 0 to 1, it increased the probability of only having plots in the traditional oasis by almost 0.3, and was significant in all specifications. While the negative sign for age is intuitive, surprisingly is was not significant. However, this variable was closely correlated with year the farming activity started, which may explain the lack of significance. Education did not appear to differ with the group of farmers, as the coefficient was not significant.

Turning now to farmers' perceptions of and attitudes to water, the only variable that appeared to differentiate farmers who cultivated plots in extension areas from farmers who only cultivated plots in the traditional oasis was cooperation to resolve conflicts. GDA farmers showed less preference for cooperation to solve water conflicts than farmers with plots in extension areas. To better understand this result, we need to recall that both farmers in extensions and in the traditional oasis gave a higher score to cooperation between farmers than to "better management rules" to solve conflicts about water. However, the tendency towards cooperation seemed to be even higher in farmers with plots in the extensions than in farmers who only had plots in the traditional oasis. This result is consistent with the right-hand bar graph in Figure 5, where the bar corresponding to extension farmers is visi-bly higher than the bar corresponding to GDA farmers. Neither the perception of water conflict nor the perception of access to water was significant, confirming the findings of the previous section, i.e., the global similarity of perceptions of water by farmers who cultivated plots in both areas of the oasis.

To sum up, the results of the probit model indicate that, compared to farmers who only cultivated plots in the traditional oasis, farmers with plots in extensions started their activity later, were more willing to buy additional land, had larger farms, and were not members of the association for the protection of the oasis. These were the main variables that distinguished "extension and mixed farmers", on one hand, and "GDA farmers", on the other. Conversely, the cropping system (monoculture in both areas), the presence of a borehole, the type of irrigation and the water extraction system did not seem to distinguish farmers with plots in the extension from GDA farmers. In terms of perceptions about water, the only significant difference was more confidence in cooperation as a way to solve water conflicts by farmers with plots in the extensions. However, this result is mitigated by the fact that conflicts are not considered to be a major problem in the oasis, and furthermore, farmers in both areas give a higher score to collaboration among themselves than to "better management rules" for solving water conflicts.

Discussion and conclusion

The rapidly evolving dynamics around groundwater exploitation in the Mediterranean region, particularly in Tunisia, call for a thorough analysis of the causes of the water resources depletion as a result of the so-called 'groundwater economy' [START_REF] Kuper | Liberation or anarchy? The Janus nature of groundwater use on North Africa's new irrigation frontiers[END_REF][START_REF] Amichi | Des serres et des hommes : des exploitations motrices de l'expansion territoriale et de l'ascension socioprofessionnelle sur un front pionnier de l'agriculture saharienne en Algérie[END_REF]. Oases are highly productive and delicate ecosystems which, in recent decades, have undergone a radical change in trends in terms of intensification of the agricultural systems and groundwater use.

The Governorate of Kebili, Southern Tunisia, with over 140 palm oases, is the main date producer in the country with 61% of the overall national production in 2016 (Agence de Promotion de l'Industrie et de l'Innovation, 2017). [START_REF] Trigui | Implication of hydrogeological and hydrodynamic setting of water quality in the Complex Terminal Aquifer in Kebili (southern Tunisia): The use of geochemical indicators and modelling[END_REF] consider that agricultural water uses are among the main reasons for water depletion of the Complex terminal aquifer in Kebili, which is the main source of water in the studied area. According to some authors [START_REF] Petit | Can agricultural groundwater economies collapse? An inquiry into the pathways of four groundwater economies under threat[END_REF], the overexploitation of groundwater resources confirmed in this case by [START_REF] Trigui | Implication of hydrogeological and hydrodynamic setting of water quality in the Complex Terminal Aquifer in Kebili (southern Tunisia): The use of geochemical indicators and modelling[END_REF] will lead to the collapse of the system in the short or medium term if drastic measures are not taken rapidly.

One potential measure is a new approach to water management, in which water users (mainly farmers, in the Tunisian oases) collaborate and define rules through collaboration among peers rather than complying with rules imposed by the existing organisations. Indeed, previous studies [START_REF] Farolfi | Information provision and willingness to pay irrigation water in Tunisian local associations for agricultural development. An experimental economics study[END_REF][START_REF] Mouri | De l'association d'intérêt collectif au groupement de développement agricole : le changement institutionnel et son impact sur le fonctionnement des périmètres publics irrigués tunisiens[END_REF] have shown that in Tunisia, farmers do not perceive the actual decentralised water management organisations (the GDA) as legitimate and as capable of guaranteeing adequate and sustainable management of the resource. Other studies [START_REF] Hassen | To what extend corruption and free-riding behavior affect technical and water use efficiencies of small scale irrigated farms[END_REF] underline the fact that most Tunisian water user associations are in crisis and offer poor service to their members.

The rapidly evolving dynamics in Tunisian oases apply particularly in the so-called extensions, in which farms were established more recently, and that occupy the land on the margins of farms located in the traditional oasis, where the official water management organisations (GDA) operate [START_REF] Ghazouani | Farmers' Perceptions and Engineering Approach in the Modernization of a Community-Managed Irrigation Scheme. A Case Study from an Oasis of the Nefzawa (South of Tunisia)[END_REF][START_REF] Mekki | Management of groundwater resources in relation to oasis sustainability: The case of the Nefzawa region in Tunisia[END_REF]. Farms in the extensions get their water from private boreholes which are not declared to the local water management authority (CRDA). These farms are often considered as the main cause of groundwater overexploitation in Tunisian oases [START_REF] Mekki | Management of groundwater resources in relation to oasis sustainability: The case of the Nefzawa region in Tunisia[END_REF].

The results of the survey conducted in Jemna oasis showed that farmers who cultivated plots in extension areas had distinctive characteristics such as having started their farming activity more recently, their willingness to buy additional land, and the fact their farms are larger. In contrast, the values of some variables such as the 11 Where institutions are rules agreed by all in a society, and where the best rules are those that emerge from actors' concertation, negotiation, and not those imposed exogenously by the existing organisations. type of cropping system (monoculture) and the presence of a borehole on the farm were similar in all three farmers' groups.

The differences between farmers who farmed plots in the extensions and those who only farmed plots in the traditional oasis are less obvious when it comes to farmers' perceptions of water problems and possible solutions. All the farmers in the Jemna oasis clearly perceive the limited availability of, access to, and the poor quality of the water resource. However, they do not believe that these problems are a source of conflicts among farmers. Their trust in collaboration between farmers is greater than their trust in better rules produced by existing organisations to solve possible water conflicts and achieve better water management. They are willing to collaborate and think that other farmers are as willing as they are. The location of farmers' plots in the traditional oasis or in the extensions had no significant effects on these perceptions.

These preliminary results, if confirmed, would have important policy implications, as cooperation and trust are key ingredients in a possible new approach to water management. Following Ostrom's sustainable governance principles [START_REF] Ostrom | Governing the commons: the evolution of institutions for collective action: The Political economy of institutions and decisions[END_REF], 11 one can consider management of groundwater as a common-pool resource (CPR) problem, where dialogue, information sharing and communication between farmers are crucial to reach sustainability. In the resource economics literature, mechanisms have recently been proposed [START_REF] Yao | Effectiveness of the approval mechanism for CPR dilemmas: unanimity versus majority rule[END_REF] to reduce the over-exploitation of CPR through communication among resource users and the introduction of CPR management rules, such as the approval mechanism (a system where CPR users first propose extractions and then approve or disapprove them to decide their implementation). These mechanisms can be imposed by the existing organisations (in this case, the GDA) or defined by the group of farmers themselves through a process of discussion and negotiation. The approval mechanism, along with other forms of CPR management, could be tested in the Tunisian oases to assess its acceptability and possible effectiveness in the management of groundwater resources.

This work has several limitations. First, due to the limited time and resources available, and because the Covid-19 pandemic further constrained the survey, the sample on which this paper is based is small, and the procedure for its selection is potentially conducive to statistical biases. Additionally, only farmers who were able to read and who owned a smartphone or a personal computer were able to take part in the online survey. This may have caused an auto-selection bias. Second, the survey, based on an electronic form filled in by the farmers on their smartphone, was not an ideal context to ask open questions. For this reason, all the questions were closed (yes/no, or multiple choices). On the one hand, this format considerably reduces the risk of errors and the time of completion of the questionnaire, also limiting the risk that the respondents give up and do not complete the survey. On the other hand, closed questions are less informative, and do not offer the respondents the opportunity to explain the reasons and the motivations for their responses. Quick interviews are perhaps not the right method to elicit conflicts, especially if no specific issues such as conflicts about water turns, water thefts, or pipeline damages are mentioned in the survey. Furthermore, farmers advocating less rules and more dialogue can be those currently benefitting more from weak or/and unclear rules. The format of the survey is thus another limitation of the study. Finally, this work is based on a single oasis located in Southern Tunisia. The generalization of our results to other oases in Tunisia and elsewhere is therefore not possible at this stage, and this study should therefore be considered as an exploratory and preliminary work, open to future developments. In particular, the existence of an association for the defence of the oasis in Jemna, which is not the case in all oases, may have an influence on the degree of trust the farmers have in collaboration to improve water management.

Future research pathways along the lines of this work therefore involve surveys based on larger and differently selected samples, in other oases in Tunisia and in North Africa to identify the so-cio-economic characteristics of farmers who cultivate plots in traditional oasis and in extension areas, as well as their perceptions of water problems and possible solutions to improve water management. More detailed and qualitative interviews, to avoid the potential biases coming from quick interviews as discussed above, are needed as well. These surveys will confirm or invalidate the findings of the present work and possibly allow their generalization. Another important perspective for future research, if these preliminary findings are confirmed, is the design and testing of governance mechanisms, such as the approval mechanism [START_REF] Yao | Effectiveness of the approval mechanism for CPR dilemmas: unanimity versus majority rule[END_REF], to improve groundwater management in Tunisian oases.

Figure 1 -

 1 Figure 1 -Geographical location of Jemna oasis.

Figure 2 -

 2 Figure 2 -Level of satisfaction concerning GDA water management and perception of GDA rules designed to guarantee enough water for everyone at the right price.

Figure 3 -

 3 Figure 3 -Perception of water quality, quantity, and access in the oasis.

Figure 4 -

 4 Figure 4 -Perception of conflicts concerning water in the oasis by the three groups of farmers.

Figure 5 -

 5 Figure 5 -How to solve the conflicts in the oasis: better rules vs collaboration among farmers.

Figure 6 -

 6 Figure 6 -Willingness to collaborate with other farmers and perception of other farmers' willingness to collaborate in better water management in the oasis.

Figure 7 -

 7 Figure 7 -Trust in public organisations and in other farmers for better water management.

Table 1 -

 1 Age of the farmers, size of their farm and year of beginning of farming for the three groups of farmers in Jemna. Farmers in the extension areas only get water from private boreholes. One third of the GDA farmers interviewed claimed to have a private borehole. Surprisingly, one third of the mixed farmers reported having no private borehole.

		Freq.*	Mean area (ha)	Mean age (years)	Mean starting year
	Extension farmers	10	2.5	47	2005
	GDA farmers	24	0.9	58	1989
	Mixed farmers	31	2.4	48	2000
	* According to previous surveys quoted in section 2.1, extension farmers represent 34% of the population of
	farmers in Jemna. Therefore extension farmers are underrepresented in our sample (15%).

Table 2 -

 2 Number of boreholes per farmer, depth of the borehole, and year of drilling for the three groups of farmers in Jemna.

		Number of private	Mean depth	Mean year of drilling
		boreholes/farmer	of the borehole (m)	the borehole
	Extension farmers	1.0	161.0	2009
	GDA farmers	0.3	123.6	2008
	Mixed farmers	0.7	129.0

Table 3 -

 3 Characteristics of water turns and GDA farmers' and mixed farmers' level of satisfaction.

Table 4 -

 4 Variables that distinguished farmers who only farmed plots in the traditional oasis versus farmers who farmed plots in extension areas -Probit estimation with average marginal effects.

		1	2	3	4	5
	VARIABLES	Dependent variable: plots only in the traditional oasis (1) versus plots in the extensions (0)
		dy/dx	dy/dx	dy/dx	dy/dx	dy/dx
	Farm size	-0.103* (0.0553)	-0.101* (0.0562)	-0.124* (0.0695)	-0.116* (0.0698)	-0.114 (0.0697)
	Year farming	-0.00947***	-0.00988***	-0.0107**	-0.0105**	-0.0102**
	activity started	(0.00243)	(0.00370)	(0.00438)	(0.00446)	(0.00409)
	Willingness to	-0.239***	-0.241***	-0.223**	-0.211**	-0.183**
	buy additional land	(0.0765)	(0.0801)	(0.0899)	(0.0981)	(0.0882)
	Production system:
	Two layer	0.149	0.147	0.111	0.115	0.0779
	system	(0.147)	(0.150)	(0.157)	(0.162)	(0.156)
	Three layer	0.0820	0.0914	0.353	0.376	0.269
	system	(0.217)	(0.233)	(0.597)	(0.493)	(0.845)
	Borehole	-0.120 (0.0752)	-0.124 (0.0800)	-0.114 (0.0864)	-0.104 (0.102)	-0.0827 (0.0937)
	Farming main	0.178*	0.181*	0.193*	0.169	0.150
	activity	(0.0926)	(0.0946)	(0.104)	(0.125)	(0.114)
	Member of the	0.293**	0.297**	0.310**	0.289**	0.306**
	association	(0.124)	(0.127)	(0.135)	(0.145)	(0.139)
	Age		-0.00654 (0.0373)	-0.0173 (0.0416)	-0.0171 (0.0421)	-0.0167 (0.0410)
	Education		-0.000839 (0.0761)	0.0156 (0.0825)	0.0290 (0.0925)	-0.0258 (0.0867)
	Water conflict				-0.0199 (0.0582)	-0.00755 (0.0496)
	Access to water				-0.0237 (0.0893)	-0.0188 (0.0825)
	Cooperation to					-0.0873**
	resolve conflict					(0.0417)
	Observations	61	61	53	53	53
	Note: Robust standard errors are in brackets. * denotes significance at the 10-percent level, ** at the 5-percent
	level and *** at the 1-percent level.

The terms institution and organisation are used here following[START_REF] Bromley | Land and water problems: an institutional perspective[END_REF]. Institutions are collective conventions and rules that establish acceptable standards of individual and group behaviour. Organizations are defined by institutions: the organization is the operationalization of the institutions.

2 Funded by the Institute for AgriculturalResearch and High Level Training (IRESA)

Tunisia. 3 While traditional oases today correspond to GDA areas, the term 'extensions' refers to plots established since the 1970s that occupy land at the edge of the traditional oases, and obtain water through illicit private boreholes that are not declared to the local authority for water management (CRDA).

Acknowledgments

The study was conducted in the framework of the IDES project financed by IRESA, Tunisia, and with the support of the SIRMA partnership platform (https://www.cirad.fr/en/worldwide/ platforms-in-partnership/sirma).

The authors are grateful to Mr Tahar Etahri, Mrs Wafa Koussani, Mr Oussama Rhouma, and Mrs Nada Ben Mansour for their help and facilitation work during the survey implementation, and to the Jemna farmers who accepted to complete the survey.

The authors would like to thank the two reviewers for their useful comments and suggestions, which have improved the quality of the manuscript.


Christoph Garth

Charles Gueunet

Pierre Guillou

Federico Iuricich

Joshua A Levine

Jonas Lukasczyk

Mathieu Pont

Julien Tierny

Jules Vidal

Bei Wang

Charles Gueunet Kitware

Florian Wetzels

Topological Analysis of Ensemble Scalar Data with TTK, A Sequel

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

LEVEL OF THE TUTORIAL

This tutorial is targeted at a Beginner to Intermediate audience.

POTENTIAL SCHEDULE CONFLICTS

If possible, we would like to avoid any scheduling overlap with IEEE LDAV 2022 and the TopoInVis 2022 workshop. Coauthor Tierny is a cochair of TopoInVis this year, and many of the speakers, as well as the potential attendees, are members of both communities.

ABSTRACT

This tutorial presents topological methods for data analysis and visualization from a user's perspective, with the Topology ToolKit (TTK), an open-source library for topological data analysis. In particular, similarly to 2021, this year's tutorial has a special focus on ensemble data analysis with TTK, but with an updated content. Topological methods have gained in popularity and maturity over the last twenty years and success stories of established methods have been documented in a wide range of applications (combustion, chemistry, astrophysics, material sciences, etc.) with both acquired and simulated data, in both post-hoc and in-situ contexts. This tutorial provides a beginner's introduction to topological methods for practitioners, researchers, students, and lecturers, with a special emphasis towards ensemble data analysis. In particular, instead of focusing on theoretical aspects and algorithmic details, this tutorial focuses on how topological methods can be used in practice to reduce ensemble datasets into concise yet meaningful topological data representations and how these representations can support advanced analysis. The tutorial describes in detail how to achieve these tasks with TTK. In contrast to the first iterations of this tutorial [START_REF] Falk | Topological data analysis made easy with the topology toolkit, a sequel[END_REF][START_REF] Falk | Topological Data Analysis Made Easy with the Topology ToolKit, What is New?[END_REF][START_REF] Favelier | Topological data analysis made easy with the Topology Toolkit[END_REF], this iteration focuses on the specific usage of TTK for ensemble data analysis, similarly to the 2021 edition [START_REF] Garth | Topological Analysis of Ensemble Scalar Data with TTK[END_REF], but with an updated content, including updated or additional features for ensemble data processing. First, we provide a general introduction to topological methods and their application in data analysis, and a brief overview of TTK's main entry point for end users, namely ParaView, will be presented. Second, we detail TTK's software infrastructure for ensemble data analysis, including TTK's Docker support (to facilitate its deployment on computing servers), a tour of the topological data representations supported by TTK, and lastly TTK's cinema support (to manipulate ensemble of topological data representations with a database formalism). Third, we will present concrete use cases of ensemble data analysis and visualization, using contour tree alignment as well as ensemble clustering and summarization with persistence diagrams and merge trees. Presenters of this tutorial include experts in topological methods, core authors of TTK as well as active users, coming from academia and industry. This tutorial mostly targets students, practitioners and researchers who are not necessarily experts in topological methods but who are interested in using them in their daily tasks. We also target researchers already familiar to topological methods and who are interested in using or contributing to TTK. We kindly ask potential attendees to optionally pre-register at the following address, in order for us to reach out to them ahead of the tutorial with information updates (for instance, last minute updates, instructions for the download of the tutorial material package, etc.): https://forms.gle/9b7TTERsjMs49g9m8 Tutorial web page (including all material, TTK pre-installs in virtual machines, code, data, demos, video tutorials, slides, etc): https://topology-tool-kit.github.io/ieeeVisTutorial.html

TUTORIAL ORGANIZATION

Online organization If this proposal was accepted, the tutorial would be organized in hybrid-mode, in accordance to the overall organization of IEEE VIS 2022. For this, we would be happy to adapt our organization to the technical recommendations from the IEEE VIS organizers (for instance, if needed: talk pre-recording, online discussions with Discord, YouTube broadcasting). Motivations Topological analysis techniques [START_REF] Heine | A survey of topology-based methods in visualization[END_REF][START_REF] Pascucci | Topological Methods in Data Analysis and Visualization: Theory, Algorithms and Applications[END_REF][START_REF] Tierny | Topological Data Analysis for Scientific Visualization[END_REF] have shown to be practical solutions in various contexts: isosurface extraction [START_REF] Carr | Simplifying flexible isosurfaces using local geometric measures[END_REF][START_REF] Santos | Enabling advanced visualization tools in a web-based simulation monitoring system[END_REF], feature tracking [START_REF] Soler | Lifted wasserstein matcher for fast and robust topology tracking[END_REF], volume rendering [START_REF] Weber | Topology-controlled volume rendering[END_REF], data simplification [START_REF] Lukasczyk | Localized Topological Simplification of Scalar Data[END_REF][START_REF] Tierny | Generalized topological simplification of scalar fields on surfaces[END_REF] and compression [START_REF] Soler | Topologically controlled lossy compression[END_REF], similarity estimation [START_REF] Favelier | Persistence Atlas for Critical Point Variability in Ensembles[END_REF][START_REF] Soler | Ranking Viscous Finger Simulations to an Acquired Ground Truth with Topology-Aware Matchings[END_REF][START_REF] Tierny | Partial 3D shape retrieval by reeb pattern unfolding[END_REF][START_REF] Vidal | Progressive Wasserstein Barycenters of Persistence Diagrams[END_REF], geometry processing [START_REF] Tierny | Interactive quadrangulation with Reeb atlases and connectivity textures[END_REF][START_REF] Vintescu | Conformal factor persistence for fast hierarchical cone extraction[END_REF] or data science [START_REF] Cotsakis | Implementing Persistence-Based Clustering of Point Clouds in the Topology ToolKit[END_REF][START_REF] Doraiswamy | TopoMap: A 0-dimensional Homology Preserving Projection of High-Dimensional Data[END_REF]. They enable the concise and complete capture of the structure of the input data into high-level topological data representations such as contour trees [START_REF] Carr | Computing contour trees in all dimensions[END_REF][START_REF] Gueunet | Contour forests: Fast multi-threaded augmented contour trees[END_REF][START_REF] Gueunet | Task-based Augmented Merge Trees with Fibonacci Heaps[END_REF][START_REF] Gueunet | Task-based Augmented Contour Trees with Fibonacci heaps[END_REF], Reeb graphs [START_REF] Gueunet | Task-based Augmented Reeb Graphs with Dynamic ST-Trees[END_REF][START_REF] Parsa | A deterministic o(m log m) time algorithm for the reeb graph[END_REF][START_REF] Pascucci | Robust on-line computation of Reeb graphs: simplicity and speed[END_REF][START_REF] Tierny | Loop surgery for volumetric meshes: Reeb graphs reduced to contour trees[END_REF], or Morse-Smale complexes [START_REF] Floriani | Morse complexes for shape segmentation and homological analysis: discrete models and algorithms[END_REF][START_REF] Gyulassy | A practical approach to morse-smale complex computation: Scalability and generality[END_REF][START_REF] Gyulassy | Conforming morse-smale complexes[END_REF]. Successful applications in a variety of fields of science have been documented (combustion [START_REF] Bremer | Interactive exploration and analysis of large scale simulations using topology-based data segmentation[END_REF][START_REF] Gyulassy | Stability of dissipation elements: A case study in combustion[END_REF][START_REF] Laney | Understanding the structure of the turbulent mixing layer in hydrodynamic instabilities[END_REF], fluid dynamics [START_REF] Bridel-Bertomeu | Topological analysis of high velocity turbulent flow[END_REF][START_REF] Chen | Topology analysis of time-dependent multi-fluid data using the reeb graph[END_REF][START_REF] Kasten | Two-dimensional time-dependent vortex regions based on the acceleration magnitude[END_REF], material sciences [START_REF] Favelier | Visualizing ensembles of viscous fingers[END_REF][START_REF] Gyulassy | Topologically Clean Distance Fields[END_REF][START_REF] Lukasczyk | Viscous fingering: A topological visual analytic approach[END_REF], chemistry [START_REF] Bhatia | Topoms: Comprehensive topological exploration for molecular and condensed-matter systems[END_REF][START_REF] Guenther | Characterizing molecular interactions in chemical systems[END_REF][START_REF] Olejniczak | A Topological Data Analysis Perspective on Non-Covalent Interactions in Relativistic Calculations[END_REF], and astrophysics [START_REF] Shivashankar | Felix: A topology based framework for visual exploration of cosmic filaments[END_REF][START_REF] Sousbie | The persistent cosmic web and its filamentary structure: Theory and implementations[END_REF]), which further demonstrates the importance of these techniques. While reference textbooks have been published [START_REF] Edelsbrunner | Computational Topology: An Introduction[END_REF], topological methods have not yet been widely adopted as a standard data analysis tool. We believe one of the reasons for this is the lack of open-source software that implement these algorithms in a generic, user-friendly, and efficient way. The Topology ToolKit (TTK) [START_REF] Bin Masood | An Overview of the Topology ToolKit[END_REF][START_REF] Lukasczyk | Report of the TopoInVis TTK Hackathon: Experiences, Lessons Learned, and Perspectives[END_REF][START_REF] Tierny | The Topology ToolKit[END_REF] has been released (BSD license) to fill this gap and 17 institutions have contributed to its development so far. Since it release in 2017, TTK's website collected 356k pageviews, from 42k visitors. This indicates that a user base exists and that further efforts towards the explanation of TTK's usage would be beneficial to the community. Target audience This tutorial targets beginners, students, practitioners, and researchers who are not experts in topological methods. It also targets researchers already familiar to topological methods and who are interested in using TTK for ensemble data analysis. Tutorial goals The goals of this tutorial are to present the key tools in topological data analysis (the Persistence diagram, the Reeb graph and its variants, the Morse-Smale complex, etc.) and how they can be used in practice for ensemble data analysis. All examples will be illustrated with TTK. We expect participants to become capable of using TTK with ParaView independently, after attending the tutorial. Hands-on material A large part of the tutorial will be dedicated to detailed example demos that the participants will be invited to reproduce. We will provide a rich material package including TTK pre-installs in virtual machines, (to be used by attendees during the tutorial), example ensemble datasets, demos, etc. Most of this material is already available on TTK's website. Our idea is that participants with a laptop will be able to follow along, regardless of their native OS. Attendees who attend just to listen and learn will receive sufficient material to try our examples at home. Optional pre-registration In previous editions, we observed that attendees would benefit from having time before the tutorial to install materials and have their systems set up with the hands-on material. If our proposal is accepted, we will use the following on-line form (https://forms.gle/9b7TTERsjMs49g9m8) to notify audiences of where and how to download the material and build a mailing list to help form an informal community for the tutorial. Proposal strengths In contrast to previous tutorials on topological methods [START_REF] Weber | Scalar topology in visual data analysis[END_REF], we believe this proposal to have a unique concrete and applicative appeal, by its focus on the usage of topological methods rather than on their foundations. Thus, we expect it to attract a larger audience than the specific subset of IEEE VIS attendees typically found in traditional topology sessions. Moreover, in comparison to the previous editions of this tutorial, this year's edition will have a special emphasis on ensemble data analysis, to exemplify TTK's features on a focused topic. We believe that the list of presenters is also a strength of this proposal. First, it includes topology experts as well as core developers and users of TTK. More importantly, it includes researchers with a variety of experience profiles (Ph.D. students, post-docs, professors) and backgrounds (industry, academia), which will ease interactions with a potentially heterogeneous audience. Moreover, the particularly large number of presenters has two merits. First, it imposes a mini-symposium structure, where speakers will give presentation lasting between 10 and 20 minutes, which will result in a lively rhythm in the overall tutorial. Second, this large number of presenters will be instrumental during the hands-on exercises, as there will be enough presenters such that one presenter can assist a small group of attendees (typically 3 to 4). Finally, we believe the detailed program of the tutorial (see Sect. 4) achieves a balance between concepts and concrete examples. Detailed content The tutorial is divided into three main parts (each part being subdivided into modules), for a target duration of approximately 3 hours and a half. These three groups of modules can be organized differently to fit any standard structure for breaks to match the tutorial schedule of IEEE VIS. After the tutorial concludes, we will make all content available from our website. A. Preliminaries (70 minutes) A1. General introduction (10 minutes, by Julien Tierny) This talk will provide an overview of the tutorial and discuss how concise topological data signatures can be used to reduce large-scale ensemble data, and still enable advanced analysis. A2. Introduction to topological methods for data analysis (30 minutes, Bei Wang) This talk will present the core tools in topological data analysis (critical points, persistence diagrams [START_REF] Edelsbrunner | Computational Topology: An Introduction[END_REF], Reeb graphs and their variants [6, 21-23, 39, 51] and Morse-Smale complexes). In particular, it will detail how these tools can be used for data segmentation and feature extraction. A3. Introduction to ParaView (30 minutes, by Charles Gueunet) This talk will provide a brief description of ParaView's main interface [START_REF] Ahrens | Paraview: An end-user tool for large-data visualization[END_REF], in order to support its usage for beginners in the rest of the tutorial. This will cover the usage of filters, pipeline design, view manipulation, and Python exports as well as a quick introduction to Catalyst (for in-situ computations). B. TTK infrastructure for ensemble data analysis (60 minutes) B1. Running TTK with Docker (10 minutes, by Christoph Garth) This talk will describe how to use TTK's most recent Docker support, which is useful for deploying TTK on high-performance infrastructures (for the in-situ computation of topological signatures). B2. A tour of TTK (30 minutes, by Joshua Levine) This talk will provide an overview of the topological signatures supported by TTK and will illustrate how to apply them on concrete examples. B3. TTK Compact triangualtions (10 minutes, Federico Iuricich) This talk will introduce TTK's novel compact triangulation data structure [START_REF] Liu | TopoCluster: A Localized Data Structure for Topology-based Visualization[END_REF], specialized for the handling of large datasets. B4. TTK Cinema support (10 minutes, Jonas Lukasczyk) This talk will introduce TTK's Cinema support for storing and manipulating databases of topological signatures representing an ensemble. C. Ensemble processing with TTK (50 minutes) C1. Contour tree alignment (10 minutes, by Florian Wetzels) This talk will introduce the contour tree alignment module of TTK [START_REF] Lohfink | Fuzzy contour trees: Alignment and joint layout of multiple contour trees[END_REF], which enables the simultaneous and coherent planar layout of an ensemble of contour trees (representing an ensemble dataset) for visual inspection purposes. C2. Ensembles of Persistence Diagrams (10 minutes, by Jules Vidal) This talk will show how to efficiently compare and cluster the members of an ensemble based on their persistence diagram [START_REF] Vidal | Progressive Wasserstein Barycenters of Persistence Diagrams[END_REF]. C3. Ensembles of Merge trees (10 minutes, by Mathieu Pont) This talk will show how to efficiently compare and cluster the members of an ensemble based on their merge tree [START_REF] Pont | Wasserstein Distances, Geodesics and Barycenters of Merge Trees[END_REF], an alternate, more discriminant topological descriptor. C4. Ensemble summarization with linked planar views (10 minutes, by Pierre Guillou) This talk will show step-by-step how to generate, with multidimensional scaling, planar summarizations of the input ensemble, where each member is represented as a point in 2D and where similar members (in terms of their topological signatures) are projected in similar locations. Linked views, related to each point of the summarization, enable the visual inspection of each topological signature. Together, the planar summarization and its detailed linked view enable the visual analysis of global trends in the ensemble. C5. Concluding remarks (10 minutes, Julien Tierny) This talk will conclude the tutorial and discuss perspectives and current efforts.

BACKGROUND AND CONTACT INFORMATION

Christoph Garthgarth@cs.uni-kl.de -is a professor of computer science at Technische Universität Kaiserslautern, and head of the scientific visualization group there. His research interests encompass the visualization and analysis of large scale data sets using methods from topological analysis, feature extraction, visual analytics, and high-performance computing, among others. In this context, he has employed TTK in teaching, to provide students with an in-depth

Figure 1 :

 1 Figure 1: TTK is a software platform for topological data analysis in scientific visualization. It is both easily accessible to end users (ParaView plugins (a), VTK-based generic GUIs (b) or command-line programs (c)) and flexible for developers (Python (d), VTK/C++ (e) or dependence-free C++ (f) bindings). TTK provides an efficient and unified approach to topological data representation and simplification, which enables in this example a discrete Morse-Smale complex (a) to comply to the level of simplification dictated by a piecewise linear persistence diagram (bottom-right linked view, a). Code snippets are provided (d-f) to reproduce this pipeline.

ACKNOWLEDGMENTS

This work is partially supported by the European Commission grant ERC-2019-COG "TORI" (ref. 863464, https://erctori.github.io/). This work is also supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, under Award Number(s) DE-SC-0019039.

understanding of topological methods, as well as for his research, as a robust and mature basis to develop novel visualization algorithms. Charles Gueunetcharles.gueunet@kitware.com -is currently an R&D engineer at Kitware. He received his PhD from Sorbonne Université (Paris, France) in 2019. He worked on high performance topological data analysis using level-set based abstractions. He is the author of several contour tree and Reeb graph modules in TTK. Pierre Guilloupierre.guillou@sorbonne-universite.fr -is a research engineer at Sorbonne University. He received his PhD from Mines ParisTech in 2016. He is an active contributor to TTK and the author of many modules created for the VESTEC project. Federico Iuricichfiurici@g.clemson.edu -is an assistant professor in the School of Computing at Clemson University and a member of the Visual Computing Lab. He received his Ph.D. in Computer Science at the University of Genova (Italy) in 2014. Before joining Clemson, he has been a postdoctoral fellow in the Department of Computer Science at the University of Maryland, at College Park. His research expertise lies in topological methods for data analysis and visualization with a focus on unstructured data. Joshua A. Levinejosh@email.arizona.edu -is an associate professor in the Department of Computer Science at University of Arizona. Prior to starting at Arizona, he was an assistant professor at Clemson University, and before that a postdoctoral research associate at the University of Utah's SCI Institute. He received his PhD from The Ohio State University. His research interests include visualization, geometric modeling, topological analysis, mesh generation, vector fields, performance analysis, and computer graphics. Jonas Lukasczykjl@jluk.de -is currently a staff scientist at the Technische Universität Kaiserslautern, at which he also obtained his PhD in 2019. His work focuses on Topology-Based Visual Analytics of Large-Scale Simulations. Several of his approaches use TTK as a backbone for reliable and reproducible data analysis. Mathieu Pontmathieu.pont@sorbonne-universite.fr -is a Ph.D. student at Sorbonne Universite. He received a M.S. degree in Computer Science from Paris Descartes University in 2020. His notable contributions to TTK include distances, geodesics and barycenters of merge trees [START_REF] Pont | Wasserstein Distances, Geodesics and Barycenters of Merge Trees[END_REF], for feature tracking and ensemble clustering. Julien Tiernyjulien.tierny@sorbonne-universite.fr -received the Ph.D. degree in Computer Science from the University of Lille in 2008. He is a CNRS senior scientist, affiliated with Sorbonne Universite. Prior to his CNRS tenure, he held a Fulbright fellowship and was a postdoc researcher at the SCI Institute at the University of Utah. His expertise includes topological data analysis and visualization. He is the lead developer of the Topology ToolKit (TTK). Jules Vidaljules.vidal@sorbonne-universite.fr -is a postdoc researcher at Sorbonne Universite, from which he received a Ph.D. in Computer Science in 2021. His notable contributions to TTK include the progressive approximation of persistence diagrams [START_REF] Vidal | A Progressive Approach to Scalar Field Topology[END_REF][START_REF] Vidal | Fast Approximation of Persistence Diagrams with Guarantees[END_REF] and their distances, barycenters and clusterings [START_REF] Kontak | Statistical parameter selection for clustering persistence diagrams[END_REF][START_REF] Vidal | Progressive Wasserstein Barycenters of Persistence Diagrams[END_REF]. Bei Wangbeiwang@sci.utah.edu -is an Assistant Professor in the School of Computing and a faculty member in the Scientific Computing and Imaging (SCI) Institute, University of Utah. Her research expertise lies in the theoretical, algorithmic, and application aspects of data analysis and data visualization, with a focus on topological techniques. In particular, her research leverages topological data analysis, which provides a strong basis for transforming large, complex data into compact, structure-highlighting representations. Florian Wetzelsf wetzels13@cs.uni-kl.de -is a PhD student at the Scientific Visualization Lab at TU Kaiserslautern. Previously he did his Master Studies in Computer Science at TU Kaiserslautern. His work focuses on algorithms and techniques in scientific visualization as well as in computational biology. Through his work on Contour Tree Alignmnents he became a contributor for TTK.


g/L/min) +48%

Nutrient absorption Kong and Singh, 2008 Gastric phase = a very complex but crucial step for the whole digestion process

The digestive process pH 6.5-6.8

α-amylase

From Roger Lentle, Massey Univ. NZ

.05

Human models

De 0.8 µm microfiltration efficiency (Fauquant et al., 2009(Fauquant et al., , 2014;;Tomasula et al., 2011 ;Trouvé et al., 1991;Madec et al., 1992) Cronobacter spp.

  digestion to design new infant formulas that will have the same behaviour in the GI tract Deglaire A., Menard O., De Oliveira S., Bourlieu Ccontributing to less than 1% of the peptides -Peptides essentially come from β-casein -α-lactalbumin (ALAC) : 1% of peptides -→ Resistant to gastric digestion -→ 4 disulphide bridges -More peptides specific of pasteurised milk Milk lipids ➔ maturation of the piglet's immune system more similar than with sow's milk structure of the infant formula « orientates » the microbiota More Proteobacteria with milk fat / More Firmicutes with plant oil Bourlieu et al. Eur J Lipid Sci Technol 2016

Oliveira et al. 2016 Am J Clin Nutr De Oliveira et al. 2017 Clin Nutr Models available at INRAE for simulating digestion

	In vitro static models
	(infant, adult)

Dupont et al. 2010ab, Mol Nutr Food Res Animal models Barbé et al. 2013, 2014 Food Chem Le Huerou-Luron et al. 2016 Eur J Nutr

						In silico
						models
	12  =	12 k	whey	( V m 1 caswpd  -	1	)  + 	12 k	aggr		caswpd m	1		

Le Feunteun et al. 2014 Food Bioprocess Tech

In vitro dynamic models (infant, adult, elderly)

Menard et al.

2014, Food Chem Sanchez et al. 2015 Food Res Int .06

Cheese leucine content (g/Kg

.019

What happens when they become older (140 d)?

Vegetable Dairy Lipids Human milk Some differences remain in:

* the microbiota composition * the metabolome with 5 discriminating metabolites (including propionate) * the immune system with a reduced susceptibility to inflammation with milk lipids (lower TNFα and IL8 with dairy lipids)

The production of an infant formula with a minimally processed route impacts its nutritional, physiological and sensorial qualities Amélie Deglaire 1 , Anne Blais 2 , Juliane Calvez 2 , Géraldine Lucchi 3,4 , Karine Gourrat

Objectives of AlimaSSenS

To assess the sensory perception of these cheeses by elderly people with impaired or intact dental health (n=76)

To assess the calcium and amino acid bioavailability in conventional pigs

To design a range of cheeses with identical composition (n=4):

 exclusively made of whey proteins to provide 10 g of protein/portion and a high intake of Leucine  enriched in calcium to provide 280 mg of calcium (25% of the daily intake)

Soft

Processed Hard Whipped Texture perception

Soft and melting

Sticky and pasty

Conclusion & perspectives

Whey-based cheeses allowed to increase the [Leu] in plasma

No differences in blood [Ca] were seen during the in vivo study on pigs

The differences between casein and whey-based cheeses could be due differences in kinetics of digestion. This could result in the selective sequestration of some AA by the splanchnic area ? Or be due to oxidation of some AA before and after absorption???

In the future, we would like to determine: if other sources of calcium can increase its bioavailability how the hardness and humidity of the bolus will affect digestion in elderly if the whey-based cheeses really allow to restore muscle synthesis in elderly

The .035

Improving health properties of food by sharing our knowledge on the digestive process


Vitorino Anaïs

Anne Carvalho

Vincent Collin

Coustham

Mr Vincent Coustham

Anaïs Vitorino Carvalho

Anne Collin

Vincent Coustham
email: vincent.coustham@inrae.fr

Mitigating the

Keywords: epigenetics, environment, phenotype programing, transgenerational Session Slot

come

In recent decades, broilers have been selected on growth performance criteria, but the significant improvement in body weight and muscle growth has not been associated with a similar increase in specific visceral organs such as the heart and lungs. As a result, broilers have a reduced ability to cope with extreme environmental temperatures. To improve temperature tolerance and welfare without affecting growth, methods of early heat exposure (thermal conditioning) have been developed to improve heat tolerance in chickens later in life. For example, thermal manipulation during embryogenesis, corresponding to an increase in egg incubation temperature, has been shown to improve survival of male broilers exposed to thermal challenge at slaughter age. Another strategy, corresponding to postnatal heat exposure of chicks on day three or five of life, also promoted heat tolerance later in life. Recently, it has been shown that the molecular mechanisms contributing to the enhancement of heat tolerance in embryonic and postnatal strategies involve epigenetic reprogramming of gene expression. Epigenetics refers to modifications of gene activity that do not involve alterations in DNA sequence, such as covalent modifications of DNA and histone proteins. Epigenetic modifications are inherited from the cell cycle, are reversible in nature and are recognized as major contributors to environmental phenotypic plasticity. To date, several enduring epigenetic mechanisms have been suggested to contribute to the heat response in chickens, including histone post-translational modifications in the thermal manipulation model and DNA methylation and hydroxymethylation, histone post-translational modifications and miRNAs in the postnatal model. The transmission of epigenetic modifications induced by perinatal heat exposure to the offspring is also under investigation. In this context, we are studying the transgenerational impact of embryonic thermal manipulation on another model bird species, the Japanese quail. Preliminary results suggest that embryonic thermal manipulation has transgenerational phenotypic impacts beyond the thermally manipulated generation. Genome-wide characterization of DNA methylation, histone marks, and gene transcripts is underway and preliminary data suggest that transgenerational epigenetic mechanisms are likely involved. Funding: Part of this work was funded by the French National Research Agency, Young Researcher Project ?QuailHeatE? (ANR-15-CE02-0009-01)


To understand the mechanisms of breakdown of food matrices and their constituents in the gut and identify the beneficial/deleterious food components released during digestion To determine the impact of the structure of food matrices on nutrient bioavailability Nutrient absorption Kong and Singh, 2008 Gastric phase = a very complex but crucial step for the whole digestion process

The digestive process pH 6.5-6.8

α-amylase

From Roger Lentle, Massey Univ. NZ p. 5 .07

Fat-free matrices: 40 g/L caseins, 10 g/L whey proteins, 95 g/L lactose and minerals + marker of the meal transit (Cr 2+ -EDTA) → Gastric emptying half-time

Acid Gel

Rennet Gel .016

A large proportion of the sequence covered β-lactoglobulin : 70 % of the sequence β-casein : 67 % of the sequence p. 17 .018

High variability in patterns but some peptides present in all subjects 31 peptides present throughout digestion 14 peptides found in all the subjects Among those 5 bioactive peptides .025

  présentation Date / information / nom de l'auteur Concentration of Milk proteins in the duodenum (ELISA) • Intense and early peak with milk/ lower and delayed with gels • Intermediate behaviour with stirred gel • Low concentrations with rennet gel but casein release tends to increase over time • Only traces of milk proteins found in the

•

  More bioactive peptides identified during digestion of acid gel than rennet gel • Nature of peptides is identical (clearly defined by the digestive enzyme specificity) • Kinetics of release are different The intestinal peptidome highly depends on food structure p. 13 Titre de la présentation Date / information / nom de l'auteur Characterization of bioactive peptides released in the small intestine of human volunteers p. 14 Titre de la présentation Date / information / nom de l'auteur .014 In vivo digestion of milk proteins • Samples were characterized by ESI-MS-MS. Only peptides larger than 5 amino acids are considered • 16 subjects were fed with 30g of either: •Caseins •Whey proteins • Intestinal contents were collected through a double lumen nasogastric tube placed in their jejunum during 6 h after ingestion (location of the sampling site was controlled by radiography) • Effluents were then freeze-dried until further use. Before analysis, effluents were rehydrated in 50 mM Tris-HCl buffer pH 8.0 and 2M urea, centrifuged for 10 min at 2000 g / p. 15



  Release of casein peptides throughout digestion  Peptides generated from whey proteins digestion are larger  Generation of a unique database of dietary peptides bioaccessible présentation Date / information / nom de l'auteur

  Sections of duodenum after 10 d of administration of peptide β-CN (94-123) Before After β-CN(94-123) stimulates the mucus production in vitro (HT-29 MTX) and in vivo (rat) hydrolyzate was submitted to in vitro digestion Peptide absorption was investigated by Ussing Chambers Absorbed peptides were identified by mass spectrometry Ozorio et al. 2021 Foods présentation Date / information / nom de l'auteur

Oliveira et al. 2016 Am J Clin Nutr De Oliveira et al. 2017 Clin Nutr Models available at INRAE for simulating digestion

	In vitro static models
	(infant, adult, elderly)

Titre de la présentation Date / information / nom de l'auteur .05

Human models

De

Brodkorb et al. 2019, Nat Protocols Menard et al. 2018, Food Chem Animal models Barbé et al. 2013, 2014 Food Chem Le Huerou-Luron et al.2016 Eur J Nutr Lorieau et al 2019 Food Chem Nau et al. 2019, 2022 Food Chem

						In silico
						models
	12  =	12 k	whey	( V m 1 caswpd  -	1	)  + 	12 k	aggr		caswpd m	1		

Le Feunteun et al. 2014 Food Bioprocess Tech

In vitro dynamic models (infant, adult, elderly)

Menard et al.

2014, Food Chem Sanchez et al. 2015 Food Res Int Leroux et al. 2020, Foods Reynaud et al. 2021 Food Chem

p. 6

Titre de la présentation Date / information / nom de l'auteur Does the food structure affect the release of bioactive peptides during digestion?

p. 7

Titre de la présentation Date / information / nom de l'auteur

collected The multi-canulated mini-pigs

	The food matrices
	unheated milk ("raw" milk) 1 catheter: abdominal aorta rehydration in Ultra Low Heat powder 6 minipigs (20 ± 1kg)	macrostructure 24h-20°C, rennet 0.003 % v/w rennet gel	10 µm	pH 6.6
	water 14.5% 6 minipigs	heat treatment 90°C-10 min
	heated milk microstructure × 6 matrices × 8 sampling times after ingestion =	rennet gel 2 cannulas: 24h-20°C, rennet 0.3 % v/w end of stomach and mid-jejunum	pH 6.6
	288 plasma samples collected
		24h-20°C, GDL 3 % w/w	acid gel		pH 4
		6 minipigs
		stirred acid gel × 6 matrices × 8 sampling times after ingestion 24h-20°C, GDL 3 % w/w + mixer 2 min × 2 sampling sites		pH 4
			=
	Titre de la présentation	p. 8 576 effluent samples p. 9
	Date / information / nom de l'auteur

Titre de la présentation Date / information / nom de l'auteur

More than 16,000 milk peptides identified in the gastrointestinal tract of pigs

	Protein Sequence Activity	Reference	4 20 50 105 165 225 315
	s	1-23	EMUL	Shimizu et al. (1984)
	s	23-34	HYP	Maruyama & Suzuki (1982)
	s	30-45	MB	Meisel et al. (1991)
	s	40-52	MB	Adamson & Reynolds (1996)
	s	43-58	MB	Meisel et al. (1991)
	s	91-100	STRE	Miclo et al. (2001)
	s	99-109	MIC	McCann et al. (2006)
	s	167-180	MIC	Hayes et al. (2006)
	s	180-193	MIC	Hayes et al. (2006)
	s	1-24	MB	Miquel et al. (2005)
	s	124-146	MB	Miquel et al. (2005)
	s	183-206	TRAN	Kizawa et al. (1996)
	s	183-207	MIC	Recio & Visser (1999)
	s	189-197	HYP	Maeno et al. (1996)
	s	190-197	HYP	Maeno et al. (1996)
		1-24	MB	Bouhallab et al. (1999)
		33-52	MB	Miquel et al. (2005)
		60-80	OPI	Jinsmaa & Yoshikawa (1999)
		98-105	OXI	Rival et al. (2001)
		114-119	OPI	Jinsmaa & Yoshikawa (1999)
		132-140	HYP	Robert et al. (2004)
		192-209	IMM	Coste et al. (1992)
		193-202	IMM	Kayser & Meisel (1996)
		193-209	IMM	Coste et al. (1992)
		18-24	HYP	Lopez-Exposito et al. (2007)
		106-116	THR	Jolles et al. (1986)
	-lg	32-40	HYP	Pihlanto-Leppala et al. (2000)
	-lg	92-100	MIC	Pellegrini et al. (2001)
	-lg	142-148	HYP	Mullally et al. (1997)

p. 12 Titre de la présentation Date / information / nom de l'auteur

Bioactive peptides released during digestion differ from one matrix to another Barbé et al. 2014 Food Res Int

	Protein	Sequence	Activity	Reference	4	20	50	105	165	225	315
				Adamson & Reynolds
	s	40-52	MB	(1996)
	s	43-58	MB	Meisel et al. (1991)
	s	99-109	MIC	McCann et al. (2006)
	s	167-180	MIC	Hayes et al. (2006)
	s	180-193	MIC	Hayes et al. (2006)
	s	1-24	MB	Miquel et al. (2005)
	s	189-197	HYP	Maeno et al. (1996)
		33-52	MB	Miquel et al. (2005)
		166-175	HYP	Hayes et al. (2007)
		193-202	IMM	Kayser & Meisel (1996)
	-lg	92-100	MIC	(8))
	-lg	142-148	HYP	(9))

of data collected  4704 dietary peptides unambiguously identified prot hit num prot desc prot cover pep exp mr start peptide end score res before pep seq

										res after
	18KD Betalg D bovine	26,5	724,3362	94	94-99	99	25,15	L	VLDTDY	K
	18KD Betalg D bovine	26,5	771,3746	50	50-56	56	39,24	T	PEGDLEI	L
	18KD Betalg D bovine	26,5	837,42	93	93-99	99	26,65	V	LVLDTDY	K
	18KD Betalg D bovine	26,5	1116,4984	125 125-134 134 73,04	R	TPEVDDEALE	K
	18KD Betalg D bovine	26,5	1203,6312	42	42-51	51	42,99	V	YVEQLKPTPE	G
	18KD Betalg D bovine	26,5	1212,6165	43	43-53	53	55,16	Y	VEQLKPTPEGD	L
	18KD Betalg D bovine	26,5	1226,6485	45	45-55	55	45,06	E	QLKPTPEGDLE	I
	18KD Betalg D bovine	26,5	1244,6017	125 125-135 135 82,11	R	TPEVDDEALEK	F
	18KD Betalg D bovine	26,5	1272,6174	124 124-134 134 55,85	V	RTPEVDDEALE	K
	18KD Betalg D bovine	26,5	1325,706	43	43-54	54	60	Y	VEQLKPTPEGDL	E
	18KD Betalg D bovine	26,5	1355,6724	44	44-55	55	62,52	V	EQLKPTPEGDLE	I
	18KD Betalg D bovine	26,5	1375,6718	42	42-53	53	46,74	V	YVEQLKPTPEGD	L
	18KD Betalg D bovine	26,5	1454,7508	43	43-55	55	56,53	Y	VEQLKPTPEGDLE	I
	18KD Betalg D bovine	26,5	1567,8385	43	43-56	56	64,32	Y	VEQLKPTPEGDLEI	L
	18KD Betalg D bovine	26,5	1617,8032	42	42-55	55	36,18	V	YVEQLKPTPEGDLE	I
	24KD cas BetaB bovine	19,6	587,2972	115 115-119 119 28,04	Y	PVEPF	T
	24KD cas BetaB bovine	19,6	753,4528	81	81-87	87	43,75	T	PVVVPPF	L
	24KD cas BetaB bovine	19,6	882,4862	73	73-80	80	39,25	Q	NIPPLTQT	P
	24KD cas BetaB bovine	19,6	888,4869	59	59-66	66	49,43	L	VYPFPGPI	H
	24KD cas BetaB bovine	19,6	1220,7164	81	81-91	91	48,36	T	PVVVPPFLQPE	V
										p. 16

Titre de la présentation Date / information / nom de l'auteur .015 Example Titre de la présentation Date / information / nom de l'auteur

Boutrou et al. 2013 Am J Clin Nutr

						-CN
	1-6	RELEEL
		1-6	RELEEL
	57-66 SLVYPFPGPI 58-66 LVYPFPGPI 57-66 SLVYPFPGPI 58-66 LVYPFPGPI 58-68 LVYPFPGPIPN 58-68 LVYPFPGPIPN 59-66 VYPFPGPI 59-66 VYPFPGPI 59-67 VYPFPGPIP 59-68 VYPFPGPIPN 59-67 VYPFPGPIP 59-68 VYPFPGPIPN	57-66 SLVYPFPGPI 59-66 VYPFPGPI 59-68 VYPFPGPIPN	59-66 59-68 60-66 108-113 EMPFPK VYPFPGPI VYPFPGPIPN YPFPGPI	Anti-hypertensive Opioïd
		60-66		YPFPGPI	60-66	YPFPGPI
	60-66 61-66	YPFPGPI PFPGPI		60-67	YPFPGPIP	114-119 YPVEPF
		61-66		PFPGPI
	73-79 NIPPLTQ
		73-79 NIPPLTQ
	73-80 NIPPLTQT
		73-80 NIPPLTQT
	73-82 NIPPLTQTPV
		73-82 NIPPLTQTPV
	80-91 TPVVVPPFLQPE
		80-91 TPVVVPPFLQPE
	81-87 81-91	81-87 81-91 PVVVPPF PVVVPPFLQPE PVVVPPF PVVVPPFLQPE	81-91 PVVVPPFLQPE	Bioactive peptides
	81-92	PVVVPPFLQPEV
	83-91 84-91	81-92 83-91 84-91 VVPPFLQPE PVVVPPFLQPEV VVPPFLQPE VPPFLQPE VPPFLQPE	81-92 PVVVPPFLQPEV	are released in the
	85-091 107-113 KEMPFPK PPFLQPE PPFLQPE 107-113 KEMPFPK 85-091		gut lumen at
	108-113	108-113 EMPFPK	EMPFPK	108-113 EMPFPK
	114-119 YPVEPF 134-139 HLPLPL 114-119 YPVEPF 134-139 HLPLPL	114-119 YPVEPF	concentrations
	135-139 156-160 MFPPQ LPLPL LPLPL 156-160 MFPPQ 135-139		compatible with a
		168-173 VAPFPQ	168-173 VAPFPQ
	168-173 VAPFPQ
	170-175 VLPVPQ 171-175 LPVPQ 170-175 VLPVPQ 171-175 LPVPQ	170-175 VLPVPQ	biological action
					177-182 AVPYPQ
	194-201 QEPVLGPV
		194-201 QEPVLGPV	194-201 QEPVLGPV
	195-201	EPVLGPV
		195-201		EPVLGPV	195-201 EPVLGPV
	196-201	PVLGPV
		196-201		PVLGPV

p. 19

Titre de la présentation Date / information / nom de l'auteur

Protein Peptide

WPH ID Bioactivity Reference β-lg

1 Some of the peptides able to cross the epithelial barrier are bioactive p. 26

Titre de la présentation Date / information / nom de l'auteur

.026

Take home messages

Dietary proteins are hydrolyzed in the gastrointestinal tract into a myriad of bioactive peptides Concentrations of these bioactive peptides are sufficient to exert a biological activity in the gut lumen (antimicrobial, increase in mucus and defensins production)

Peptides up to 4 kDa are able to cross the epithelial barrier But only 0.6-3.4% of a peptide will pass through the epithelium Since the lifetime of a peptide in the bloodstream is a question of minutes, one can wonder whether bioactive peptides targeting a peripheric organ can really exert a biological activity?

p. 27 .029

Main objective: understanding the mechanisms of food digestion

29

• Harmonize the methodologies and propose guidelines for performing experiments

• Validate in vitro models towards in vivo data (animal and/or human)

• Identify the beneficial/deleterious components that are released in the gut during food digestion

• Determine the effect of the food matrix on the bioavailability of food nutrients and bioactive molecules