A Caimi

H Guillaud

O Moles

F Vieux-Champagne

P Garnier

S Grange

Y Sieffert

L Daudeville

Traditional and scientific knowledge for a sustainable vulnerability reduction of rural housing in Haiti

On January 12, 2010, a M 7.0 earthquake strikes Haiti, affecting hundreds of thousands of victims and disrupting three million lives. Observations made after the disaster revealed that, in both urban and rural areas, occupants of traditional buildings were exposed to limited risk, thanks to the moderate vulnerability of these structures to seismic stress.

In areas affected by recurrent natural hazards, vernacular architectures often reveal a great deal of ingenuity regarding the use of available resources and the development of technical devices, reducing the vulnerability of built structures. However, the relevance and potential of these solutions remain marginally recognized by scientific community and organizations involved in post-disaster reconstruction.

In the framework of the ReparH research project, funded by the French National Research Agency, a collaboration was established between researchers from the field of architecture (CRAterre-ENSAG) and engineering (3SR-UJF), together with the Haitian organization GADRU, to reflect on supporting the development of reconstruction and vulnerability reduction strategies, based on local construction methods and resources.

This paper serves to present current research works in the context of two PhD theses addressing the issue of housing in risk prone areas, from a methodological and technical point of view. The first part deals with a method for the analysis of construction practices through the identification of the characteristics of existing buildings, local know-how and factors influencing the built environment of a community. The second part relates to the development of a scientific study, resulting from exchanges between field and academic work, dealing with a building system used for reconstruction, based on locally available materials such as earth, stone and wood.

ANALYSIS OF LOCAL BUILDING PRACTICES

The development of a qualitative method for the analysis of construction practices in a specific geographic area aims to address the existing need, applicable to field work and to scientific research, to implement investigation approaches that integrate the analysis of built structures, lifestyles and resources present in situ.

As part of a PhD in architecture developed within the CRAterre-ENSAG laboratory, this work is based on an iterative approach of design, experimentation, verification and adaptation, made possible mainly through practical applications in the field, achieved in the framework of programs of housing improvement in Haiti and risk reduction and disaster preparedness in Bangladesh.

The content of this analysis involves four main subjects, relative to the factors influencing the living space and the living environment of a given community. The natural and built environments imply the physical, climatic, geological and morphological analysis of the territory. Buildings, in terms of their architectural characteristics, are designed as a response to the needs,

desires and activities of their dwellers, but also represent the materialized result of combined technologies and materials. Knowledge and know-how compose the experience and comprehension developed by a group of people in shaping their habitat and in dealing with challenges that it presents. The tangible and intangible resources available include materials, the means and capacities to implement and develop a built environment as well as the ability to prepare and respond to crises.

The methodology is based on a participatory-driven approach, actively involving local populations and stakeholders in the collection, reworking and validation of information, as well as on a flexibility of investigative processes and supports to allow the necessary adaptation to each specific context. Its implementation is structured into different phases, alternating group meetings, individual interviews, the detailed analysis of constructions and direct observations, leading to the acquisition and verification of information by integrating data from multiple sources. Group meetings are aimed at the general public and at local authorities and representatives of local organizations, as well as, in the form of focus groups, at those involved in activities related to construction, such as artisans, self-builders and people in charge of specific tasks. The analysis of existing architectures allows identifying specific architectural and building characteristics of dwellings and the lifestyles of their dwellers. Individual interviews provide an opportunity to understand the factors influencing design, implementation and evolution processes of the built environment, as well as the common practices and specific measures linked to vulnerability reduction and risk preparedness. This information is complemented with direct observations carried out by the surveyors. Graphic supports are used to facilitate discussions with the persons interviewed, and later to present the survey results to local populations.

All these methods and tools were compiled based on a literature review including materials developed for humanitarian interventions [START_REF] Abarquez | Field Practitioners' Handbook. Pathumthani : Asian Disaster Preparedness Center[END_REF]IFRC 2007IFRC et 2011)), pre and post disaster evaluations [START_REF] Cuny | Improvement of rural housing in Haiti to withstand hurricanes. Dallas : Intertect, OXFAM Regional Office for the Caribbean[END_REF][START_REF] Debray | Assessing the Vulnerability of Local Communities to Disasters: An Interactive Guide and Methodology[END_REF]; UN-HABITAT 2010) as well analysis procedures for buildings, derived from the fields of heritage preservation [START_REF] Ferrigni | Ancient Buildings and earthquakes, The Local Seismic Culture approach: principles, methods, potentialities[END_REF][START_REF] Hicyilmaz | Dhajji Dewari. Timber Building with Masonry/Stone Infill. Pakistan, India[END_REF] and engineering [START_REF] Baggio | European Communities: European Commission Joint Research Centre Institute for the Protection and Security of the Citizen[END_REF][START_REF] Hughes | The survey of earthquake damaged non-engineered structures. A field guide by EEFIT[END_REF].

Applications in Haiti

Between 2010 and 2012, an analysis of local building practices was conducted, in collaboration with Haitian associations, involving several field research trips, in the West and Southeast departments of Haiti. A special focus was given to the rural areas of Cap Rouge (Jacmel), Grande Rivière (Carrefour) and Clémansso (Kenskoff), all affected by the 2010 earthquake.

The items listed below are a portion of the collected information, allowing to capture some of the features of local houses and some existing measures taken to reduce their vulnerability to the natural hazards affecting the area [START_REF] Cuny | Improvement of rural housing in Haiti to withstand hurricanes. Dallas : Intertect, OXFAM Regional Office for the Caribbean[END_REF][START_REF] Douline | Analyses de l'habitat et des infrastructures des partenaires de Misereor affectés par le tremblement de terre du 12 janvier 2010[END_REF][START_REF] Moles | Reconstruction post séisme 2010. Etat des Lieux des différentes orientations d'intervention de partenaires Haïtiens[END_REF].

Building typologies

Across the studied areas, wooden frame housing units are the most common. Their design is based on a regular grid of wooden poles making the main structure of the building, infill techniques vary depending on the materials available locally.

Clissage is the most ancient technique. It consists of horizontal braided palm timber strips, forming panels that are inserted between the vertical elements of the wooden frame. Sometimes left exposed, these panels are usually covered on both sides with an earthen mortar or with a mixture of earth and lime. This technique allows to create lightweight structures, posing little threat to occupants as the braiding helps to avoid the possible collapse of large blocks [START_REF] Cuny | Improvement of rural housing in Haiti to withstand hurricanes. Dallas : Intertect, OXFAM Regional Office for the Caribbean[END_REF]. During the earthquake of 2010, damages to such constructions were very limited [START_REF] Audefroy | Haiti: post-earthquake lessons learned from traditional construction[END_REF][START_REF] Douline | Analyses de l'habitat et des infrastructures des partenaires de Misereor affectés par le tremblement de terre du 12 janvier 2010[END_REF] and concerned mostly the plasters, that either cracked or were pulled apart from their support. Recently, the shortage of wood and the association of such techniques with an image of poverty have led to their gradual abandonment, with a consequent loss of associated skills. However, due to its rapid implementation and the recognition of its good behavior during earthquakes, clissage has spontaneously been reused by local populations for the construction of emergency shelters and the repair of houses, based on ancient know-how.

Tiwoch is another technique that characterizes most rural dwellings present in surveyed areas, and it is very commonly applied in the construction of new buildings. It involves a supporting structure composed of wooden poles, with an infill of stone masonry and a mud, earth and lime or cement mortar.

Timber boards nailed to the poles define a third technique known as palmiste, once widespread but becoming inaccessible today due to the scarcity and high cost of wood. Aside from increasing the ease of implementation and extension of the structure, the boards serve as bracing elements, improving the general uniformity and rigidity of the structure.

Building practices reducing housing vulnerability

Many vernacular buildings incorporate devices to improve their structural behavior against the impact of natural hazards. Analysis conducted after the earthquake of 2010 revealed that, while presenting localized damage, oftentimes a consequence of previous structural deterioration, traditional buildings generated few casualties. Damages mostly affected the secondary structures of such buildings, while the main structure and most expensive portions were preserved, making them easily repairable, both financially and technically.

Indeed, builders often modified and improved constructions, developing solutions to reduce the vulnerability of structures. However, while the implementation of one of these solutions did not often improve sufficiently the behavior of the construction, it is interesting to note that several devices are generally incorporated into the same structure and that, together, they truly improve the behavior of buildings facing recurring events, such as hurricanes, but also less frequent disasters, such as earthquakes [START_REF] Mora | Analysis of Multiple Natural Hazards in Haiti (NATHAT)[END_REF].

In vernacular houses, the low height of the building helps to enhance wind resistance and, as their center of gravity is lowered, this also increases the resistance to earthquakes. Regarding wood structures, horizontal bracing at the four corners of the wall plate consolidate the structure (Fig. 1a), while at the level of the roof, diagonal braces between the ridge beam and the king posts ensure the stability of the roof structure (Fig. 1b). Mortise and tenon joints allow slight deformations of the building, while maintaining structural integrity.

In addition to the technical characteristics of wood frame partitioning, the gradual reduction on the thickness of walls and use of lighter materials on the upper portions help protect occupants in the event of a partial collapse of the walls (Fig. 1c). To increase resistance to strong winds, several devices of vernacular architectures correspond to some principles advocated by hurricane engineering as practiced today. A four pitches roof with slopes of about 30 degrees as well as the small roof overhangs reduces wind impact on the construction.

The uncoupling between the roof structure of the main house and the one of the veranda reflects the principle of structural disconnection between primary and secondary structures; the gallery plays the role of a fuse element as, even if torn out, it will not compromise the main roof structure (Fig. 2a).

In addition, some architectural elements serve a purpose beyond aesthetics and function as they also assume a structural function; aside from providing a space for safekeeping, closed granaries bring greater resistance to roof and this is especially the case for roofs with two slopes. Similarly, the enclosures of veranda made of crossed timber planks, secure the struc-tures, and even if the lower masonry wall collapses, they maintain a relative consistency and a full collapse is thus prevented (Figure 2b). The decorative friezes adorning the gables help deflect the wind flow and thus minimize depressions likely to tear off roofs [START_REF] Barré | Conception paracyclonique. À l'usage des architectes et ingénieurs[END_REF]. The existence and application of strategies for vulnerability reduction, integrated into the environmental management (Fig. 2c), the architectures, the practices and the knowledge within a given community stress the importance of systemically taking into account the characteristics of a context, by considering the multifaceted, functional, aesthetic, structural and cultural characteristics of housing structures and their relationship with their environment.

Considerations

While supporting programs centered on the repair and reconstruction of housing structures, the work started in Haiti allowed to meet two objectives. On the one hand, to collect detailed information on buildings and on vernacular skills that may contribute to improve the technical and methodological solutions offered through ongoing programs. On the other hand, to enable local actors to develop skills so as to independently conduct surveys on existing structures, to be applied as part of future risk reduction activities.

A pilot phase was launched in April of 2012 in collaboration with the Haitian association GADRU, engaged in a reconstruction program supported by the German NGO Misereor. Since July 2012, three other local associations became involved in the survey process, as a way to dispose of specific elements to adapt the processes and contents of projects, current and future, to the characteristics of each site.

This work resulted in the dissemination of the methodology developed as part of the thesis research to local partners, and its appropriation by the latter. Although this process is still ongoing, newly acquired skills have already been used independently by Haitian partners in preparation of the next phases of the reconstruction program.

The interest expressed by the partners in this work and the remarks made following numerous post-disaster interventions (Duyne Barestein 2006[START_REF] Caimi | Etat des lieux de la reconstruction post-tsunami en Indonésie[END_REF][START_REF] Jha | Safer homes, stronger communities. A handbook for reconstruction after natural disasters[END_REF] emphasize the need to implement an approach based on the specific aspects, potentials and constraints of each site, to improve the technical and economic accessibility of building proposals and to strengthen the capacities of communities in the management and handling of future crises.

The data resulting from the implementation of this methodology can form the basis of a process of development, validation and implementation of building and operational principles that may contribute to the improvement of technologies known locally and support existing dynamics.

The analysis of existing structures is combined with an anticipation of the impact of future hazards, through the identification of the technical, logistical and organizational resources on which post-disaster interventions could be based, integrating the continuity of the process of construction and evolution of the built environment within a community.

The information gathered is used to undertake a technical study of vernacular architectures, and thus develop research approaches that pave ways to the development and implementation of building activities that help to improve existing housing based on its own specificities.

To understand the characteristics of local housing and the coping strategies of local populations, and, at the same time, to recognize local knowledge and expertise, could become a real starting point toward the reduction of vulnerability in the long term.

EXPERIMENTAL STUDY OF A TYPE OF STRUCTURE IMPLEMENTED IN A CONTEXT OF POST-EARTHQUAKE RECONSTRUCTION

In Haiti, traditional buildings have long demonstrated their effectiveness against natural disasters. But yet they remain unrecognized by stakeholders in the construction field, mainly due to the lack of available scientific data. This observation is the starting point of the collaboration between researchers (architects) from the CRAterre-ENSAG laboratory, who acknowledge the value of such architectures, and researchers from the 3SR-UJF laboratory (engineers) who are capable of leading a study on the latter. In fact, the architects already collaborate with several NGOs, leading a number of construction and rehabilitation projects in rural and peri-urban areas around Haiti. The foundation of these programs is based on the idea of bringing a sustainable contribution to local populations, based on the development of local building cultures.

The first idea was to use as much as possible relevant local resources and know-how. To this end, the observation and study of traditional architectures and the interaction with local populations are essential to understand what materials are available on site, construction techniques, the methods of production and construction management and construction costs. In rural areas, a visual inspection allows to make the following observations: local populations often have a very modest income and the construction techniques used are linked to the specific geographical areas where they developed (wood frame filled with stonework bound by an earth-based mortar, timber frame panels filled with mud, stone masonry).

Road infrastructures are very limited, making the transportation of materials a complicated task. As a result, the use of steel frames and reinforced concrete is expensive. Haitians use locally available materials for construction: stones, earth and, to a lesser extent, wood. When not available, the transportation of wood is still relatively easy to manage.

Another idea was to reproduce the intelligent building methods identified during surveys, such as the bracing systems for structures, and at the same time improve existing buildings and overcome the main weaknesses of local building systems by improving, for example, ground anchorage systems and the bracing of superstructures. Thus, posts directly anchored in the ground, that tend to rot fairly quickly, are replaced by a system of poles anchored to a wall base and bracing systems are reinforced through the implementation of St Andrew's crosses.

In both cases, analysis of local building practices are a very pertinent means to identify intelligent building systems.

The results of the work described above have enabled the development of several types of model homes, achieving a compromise between costs, the respect of local cultures and seismic resistant performances: 1. timber frame, cross-braced with a stone infill 2. same structure but filled with adobe bricks or wattle and daub 3. tied natural stone masonry.

The thesis work performed at the 3S-R laboratory consisted in the study, from a seismic point of view, of one of such structural types. There is little available literature on the subject [START_REF] Ali | In-Plane Behavior of Full Scale Dhajji Walls (Wooden Braced with Stone Infill) under Quasi Static Loading[END_REF][START_REF] Ceccotti | Seismic behavior of historic timber-frame buildings in the italian dolomites[END_REF][START_REF] Meireles | A hysteretic model for "frontal" walls in Pombalino buildings[END_REF], which led to the choice of one particular type of structure. The major challenge is to provide scientific evidence of the relevance of earthquake resistant characteristics of these buildings, directly inspired by traditional buildings and building local cultures. The selected building system chosen for the study was typology 1 as as it is the most widely used in reconstruction projects in which CRAterre-ENSAG architects participate. Other alternatives were also studied through an experimental parametric analysis.

In order to analyze the behavior of a wood-frame structure with a Saint Andrew's cross type bracing and a stone infill, the study is based on a multi-scale approach aiming at understanding the behaviors, at different levels, of a housing unit subject to earthquakes (connections, elementary cell unit, the entire house). At every scale, the necessary information was obtained to predict structural behavior at a larger scale. At each level, an experimental study was conducted or will be conducted, to provide comparative data to develop a computer model that will predict the behavior of the housing structure. The scale of the totality of the structure has not yet been studied. A similar approach is applied in [START_REF] Boudaud | European seismic design of shear walls : experimental and numerical tests and observations[END_REF][START_REF] Folz | Cyclic analysis of wood shear walls[END_REF].

At the scale of connections

The assembly studied is a beam-column connection maintained by a perforated and nailed metal strip (see Fig. 3a). It governs the earthquake resistant behavior of the wall. Connections between diagonal and horizontal elements represent secondary connections (see Fig. 3b). They have a limited influence on the earthquake resistant behavior of walls and for this reason they have not been studied.

The post and beam connection was tested in terms of tensile strength and shear through three monotonic tests and one cyclic test. The influence of the number of nails and their type on structures has also been tested.

Results show that the tensile strength of the assembly is proportional to the number of nails employed. However, in terms of shear resistance, beyond 4nails the effectiveness is limited. It was also shown that the ability of nails to deform can greatly influence the quality of a connection and its brittle behavior. An assembly including 16 common nails is deformed until the nails are loosened, whereas a connection including 8 ring shank nails, allowing a resistance equivalent to the previous configuration becomes fragile and breaks through the rupture of the metal strip. In the case of a seismic resistant structure, this type of breakage must be avoided. Therefore, the use of common nails is a better option, in every way, as these are more deformable and much cheaper.

These results allow us to quickly assess the strength of this type of connection and measure its limits. These tests and results are very important for the development of construction in-situ because they provide some very concrete understanding on connections and, being an expensive product, help optimize their use based on the number of nails, their type and the characteristics of metal strips.

At the scale of the cell unit

By conceiving the wall as an assembly of wooden frames braced with St. Andrew's crosses (see Fig. 3c and3d) we can experimentally model wall configurations based on a combination of basic cells. Testings made at this intermediate structural scale can be useful to easily compare the influence of several parameters: type of infill, contribution of bracing and other technical details. As described above, several types of structures are implemented directly on site. It is therefore interesting to have the possibility to evaluate the variations in the behavior of the structure according to the building techniques employed. For this purpose, to test the walls at the scale of the cell is ideal, as this allows to test options in a fast and inexpensive way, unlike other types of testing that would take into account the wall as a whole.

Figure 4a compares the envelope curves obtained under cyclic loading for a braced cell unit filled with stone, a cell filled with adobe bricks, and empty cell and an unbraced cell with a stone infill. The curves show that type of infill has little effect on the overall response. Thus, at the level of the cell, as long as the infill is less rigid than the wood frame, it is the wood frame that governs its behavior completely, and so, in the absence of bracing, its resistance decreases much for the same reasons.

At the scale of the wall

Figure 4b shows the envelope curves obtained for a wall filled with stones and for an empty wall tested under cyclic loading. This time, contrary to results shown for the cell unit, the infill plays an important role on the global structural behavior. Thanks to the observations made in the previous paragraph, we can understand that the ductile behavior obtained in the absence of infill is explained partly first by the flexibility of secondary connections and second by their freedom of movement. So, without infill, the structure deforms more easily. These results complement the observations made at the cell level by providing additional information on the quasi-static response of this type of structure (cf. [START_REF] Vieux-Champagne | Experimental analysis of seismic resistance of shear wall in traditional haitian houses[END_REF].

Scientific results applicable on the ground

This thesis work, beyond the results reported in this paper, provides considerable support for the development of projects using this type of structure. Currently, due to their low cost and their viability in the context of rural (and peri-urban) Haiti, the use of timber framing techniques is developing at a fast pace, so much so that the Haitian Ministry of Public Works, Transport and Communication (MTPTC) has validated the timber frame and St Andrew's cross bracing system.

It will also help to bring answers to a number of technical questions that builders may have. Finally, it will provide an experimental basis that may serve as a foundation for a study predicting the behavior of structures under seismic loading.

CONCLUSIONS

Maintained throughout the research process, the connection between academic and operational settings made it possible, on the one hand, to adapt the development of research work to the actual needs of the rural Haitian context, and on the other hand, to contribute directly to the activities carried out by local stakeholders.

Combining a scientific approach and the realities on the field, this multidisciplinary collaboration between architects and engineers takes advantage of the complementary skills of partners to identify strategies for improving the resilience of local populations, based on local knowledge, dynamics and resources.

This approach allows, first, to enlarge the criteria considered in terms of research, anchoring results to real constraints and potentials, and second, to explore and experiment with methodological approaches and technical proposals that can be accessed and owned by local populations, helping to build up their capacity to respond to the challenges posed by the environment they inhabit.

Figure 1 .

 1 Figure 1. Grande Rivière : (a) bracing of the frame, (b) bracing of the roof structure, (c) gradual reduction of the thickness of the wall.

Figure 2 .

 2 Figure 2. Grande Rivière : (a) disconnection of the structure of the gallery, (b) bracing of the gallery and decorative frieze (c) Cap Rouge: reduced height and vegetation barrier as protection against strong winds.

Figure 3 .

 3 Figure 3. (a) main connection, (b) secondary connection, (c) cell unit, (d) wall.

Figure 4 .

 4 Figure 4. Force-displacement diagram at the scale of: (a) the individual cell (b) the wall

ACKNOWLEDGEMENTS

The authors wish to thank and acknowledge the support of the French National Research Agency (ANR) under reference code ANR-10-HAIT-003, as well as the CNR Ivalsa (italy) that made possible the tests on the wall, the Haitian association GADRU, the participating associations of the PADED platform and all local partners for their involvement and participation, contributing to this research project.


Jong Ho Jhee
email: jong-ho.jhee@inria.fr

Alice Rogier
email: alice.rogier-ext@aphp.fr

Dune Giraud
email: dune.giraud@aphp.fr

Emma Pinet
email: emma.pinet@aphp.fr

Brigitte Sabatier
email: brigitte.sabatier@aphp.fr

Bastien Rance
email: bastien.rance@aphp.fr

Adrien Coulet
email: adrien.coulet@inria.fr

Representation and comparison of chemotherapy protocols with ChemoKG and graph embeddings

Keywords: Chemotherapy protocol, chemotherapy regimen, knowledge graph, graph embedding, clustering 1 Proceedings Name, Month XX-XX, YYYY, City, Country

Background: Chemotherapy, a central cancer treatment, employs antineoplastic drugs to hinder cancer cell replication by disrupting DNA synthesis or mitosis. Chemotherapies follow complex protocols composed of cycles of treatment where antineoplastic and adjuvant drugs prescribed at different doses and times. Various protocols exist, with either small or large and numerous variations to others, making it hard to compare chemotherapies to each other, comparing their differential outcomes, and in the end choosing the most adapted one for a particular patient. Method: We propose ChemoKG, a knowledge graph for chemotherapy protocols that encompasses first administration programs such as drugs, dosages, treatment durations, and second drug properties and classes imported from ChEBI, DrugBank and the ATC classification. Three resources on drugs provide complementary hierarchies and chemical properties that help to better identify similar chemotherapy protocols. To this aim, we tested on ChemoKG a novel graph embedding method employing graph neural networks (GNNs) to compare nodes in the graph that represent protocols. Unlike previous approaches that focus on triple-based embeddings, the proposed method captures subgraph structures inherited from the aggregation scheme in GNNs. Results: The resulting knowledge graph encompasses 329,164 triples with 99,901 entities and 75 predicates including 1,358 chemotherapy protocols and 226 anti-cancer drugs. We performed a cluster analysis of protocol embeddings learned on ChemoKG, to propose groups of similar protocols. This will contribute in facilitating the comparison of chemotherapy themselves, and by extension to their potential effectiveness. Additionally, it should aid in analyzing gaps between commonly accepted protocols and their real-world implementation.

Introduction

Chemotherapy is a cancer treatment which employs antineoplastic drugs to hinder cancer cell replication for instance by disrupting DNA synthesis or mitosis. Chemotherapy remains a cornerstone in cancer treatment, administering cytotoxic drugs to limit tumor growth. This involves a nuanced balancing between reducing tumor size and minimizing side effects. Combining various drugs in a timely manner, adapted to patient profile and response is a common strategy to achieve this tradeoff [START_REF] Devita | A history of cancer chemotherapy[END_REF]. Indeed, each chemotherapy treatment follows a complex, but precisely defined protocol (also named regimen) composed of repeated cycles where a set of antineoplastic and adjuvant drugs are prescribed for administration with various dose, mode (continuous vs. bolus infusion) and timing. This cyclic approach is not arbitrary, it aligns with the life cycle of cancer cells and ensures optimal drug efficacy [START_REF] Khongorzul | Antibody-drug conjugates: a comprehensive review[END_REF]. Many different protocols have been described with either small or large variations, to adapt to individual factors such as age, health conditions, and genetic profiles [START_REF] Warner | HemOnc. Org: A collaborative online knowledge platform for oncology professionals[END_REF]. As a result, a large number of protocols co-exist in clinical information systems and expert databases, but they are suffering from unequal evaluation and consequently make more complicated for the clinician the choice of a protocol versus another.

The subtlety of variations in term for instance of timing (e.g., time lapse between two administrations), mode of administration (e.g., bolus vs. continuous) motivates the need for a low grain knowledge representation of protocols, especially for future studies aiming at evaluating the comparative effectiveness of treatment strategies [START_REF] Riaño | Ten years of knowledge representation for health care (2009-2018): Topics, trends, and challenges[END_REF]. In addition, such representation would enable the definition of distances between protocols, in regard to their multidimensional definition, composed of the drugs they leverage, their dose, timing, mode, classes, etc.

We introduce ChemoKG, a knowledge graph that represents chemotherapy protocols, their various dimensions, and links their constitutive drugs to various properties from ChEBI, DrugBank and the anatomical therapeutic chemical (ATC) classification. As a first illustration of the interest of ChemoKG, we propose here a clustering that group similar protocols in regard to their description in ChemoKG. The clustering relies on a novel embedding framework named RAGE, which leverages graph neural networks (GNNs) to learn a representation of protocols that considers the properties of the drug administrations present in the neighborhood of protocols in ChemoKG. Unlike other approaches that focus on triple-based embeddings, RAGE captures subgraph structures inherited from the aggregation scheme in GNNs. The clustering analysis provides a classification of protocols that we compare with two reference classifications: the first is based on cancer locations associated with protocols, the second on pharmacological groups of drugs. We evaluated RAGE embedding approach on a link prediction task; and RAGE outperforms or shows competitive performance against the selected baselines. The cluster analysis we performed with classical algorithms shows that RAGE allows for a reasonably good grouping of protocols by cancer locations, despite the fact that the graph does not contain this information. For ATC as a reference, RAGE showed the best result, in comparison to a classical method (not based on machine learning) named cumulative dose intensity (CDI).

To our knowledge, this is the first attempt to classify chemotherapy protocols on the basis of several of their features. We believe that our effort to compare chemotherapies will find applications first in the management of protocols in hospitals that historically recorded every small variation in protocols, resulting in large collections in need of structuration and cleaning; second in the definition of standard protocols as institutions have adopted different, but sometimes similar ones; and in the identification of concurrent protocols. Indirectly, we hope that comparing chemotherapy protocols will help in their relative evaluation and in the guidance for the choice for one among a set of similar ones.

The remainder of the paper is organized as follows. First, previous works on chemotherapy representation, graph embeddings and clustering from graph embeddings are presented in Section 2. Section 3 introduces ChemoKG. Section 4 describes the methodology of both the proposed graph embedding framework and its use for a clustering task. Section 5 presents our experimental results and is followed by elements of discussion and a conclusion in Section 6.

Related works

Chemotherapy databases The growing variety of chemotherapy protocols has led to a recent interest first in naming protocols in non-ambiguous ways [START_REF] Rubinstein | Standardizing chemotherapy regimen nomenclature: a proposal and evaluation of the HemOnc and National Cancer Institute Thesaurus Regimen Content[END_REF], and second in proposing repositories of the various protocols. The larger available one is HemOnc, which includes >4,000 regimens [START_REF] Warner | HemOnc. Org: A collaborative online knowledge platform for oncology professionals[END_REF]. It is a collaborative database that includes regimens description and general information about them. It started in 2011 through a collaboration of oncologists from several US University hospitals with an initial focus on the field of hematology cancers. HemOnc proposes a data schema to represent and share protocols in Owl. However, this schema does not include detailed properties of administrations and drugs. Another initiative developed in the UK is SACT [START_REF] Bright | Data resource profile: the systemic anti-cancer therapy (SACT) dataset[END_REF] that contains both adult and pediatric oncology protocols. SACT has the particularity to store data not only about protocols, but also about patients, their diagnoses and outcomes. For this reason, SACT is not shared in open access. Worth to note, a seminal work is DIOS [START_REF] Klimes | DIOS-database of formalized chemotherapeutic regimens[END_REF], that consisted of 260 protocols at the time of publication (2013) and is not accessible anymore.

Knowledge graph embeddings

The aim of knowledge graph embeddings is to project entities and relations into some continuous vector space while preserving the relation between entities [START_REF] Wang | Knowledge graph embedding: A survey of approaches and applications[END_REF]. Those entity and relation embeddings can further be used in downstream tasks, such as link prediction [START_REF] Paulheim | Knowledge graph refinement: A survey of approaches and evaluation methods[END_REF], triple classification [START_REF] Socher | Reasoning with neural tensor networks for knowledge base completion[END_REF] and entity clustering [START_REF] Gad-Elrab | Excut: Explainable embedding-based clustering over knowledge graphs[END_REF]. TransE [START_REF] Bordes | Translating embeddings for modeling multi-relational data[END_REF] is a representative approach based on a translational distance model. Given a triple (𝑠, 𝑟, 𝑜) , the relation is interpreted as a translation vector r so that the embedded entities s and o can be connected by r with low error having 𝑠 + 𝑟 ≈ 𝑜. TransE has the advantage of being simple, but has difficulty in learning 1-to-many and many-to-many relations [START_REF] Wang | Knowledge graph embedding by translating on hyperplanes[END_REF]. DistMult [START_REF] Mikolov | Distributed representations of words and phrases and their compositionality[END_REF] exploits a similarity-based scoring function to match the latent semantics of entities. It represents pairwise relations between entities in the vector space along the same dimension of relations. However, since relations between entities are over-simplified, the model consider all relations symmetric. ComplEx [START_REF] Trouillon | Complex embeddings for simple link prediction[END_REF] is an extension of DistMult that uses complex-valued embeddings so as to better model asymmetric relations. MuRE [START_REF] Balazevic | Multi-relational poincaré graph embeddings[END_REF] employs hyperbolic embedding instead of Euclidean analogues to represent hierarchical structures. RDF2Vec [START_REF] Ristoski | Rdf2vec: Rdf graph embeddings for data mining[END_REF] uses random walks on the RDF graph to create sequences of entities, which are then used as input for the model. However, it is focused on embedding entities without considering the semantics of relations. CompGCN [START_REF] Vashishth | Composition-based multi-relational graph convolutional networks[END_REF] represents relationships between entities using Graph Convolutional Networks (GCNs), which focuses on local neighborhood entities. It utilizes relation-type specific parameters to learn embeddings. More embedding techniques can be found in the following surveys [START_REF] Wang | Knowledge graph embedding: A survey of approaches and applications[END_REF][START_REF] Ji | A survey on knowledge graphs: Representation, acquisition, and applications[END_REF].

Clustering with graph embeddings Embeddings provide a representation of objects in the form of numeric vectors that is convenient for computing distances between them and consequently driving clustering analyses. To cite only few works from the biomedical domain, Monnin et al. [START_REF] Monnin | Discovering alignment relations with Graph Convolutional Networks: A biomedical case study[END_REF] clustered embeddings of pharmacogenomic relationships, Mohamed et al. [START_REF] Mohamed | Biological applications of knowledge graph embedding models[END_REF] clustered polypharmacy side-effects and Fernández-Torras et al. [START_REF] Fernández-Torras | Integrating and formatting biomedical data as pre-calculated knowledge graph embeddings in the Bioteque[END_REF] clustered drugs, diseases and genes to predict drug responses.

ChemoKG

ChemoKG is an original knowledge graph in RDF (Resource Description Framework) of chemotherapy protocols. It encompasses 1,358 protocols by instantiating the ontology ChemoOnto [START_REF] Rogier | ChemoOnto, an ontology to qualify the course of chemotherapies[END_REF][START_REF] Rogier | ChemoOnto, an ontology to qualify the course of chemotherapies[END_REF], which provides the necessary classes and relations to represent the various dimensions of protocols. As illustrated by Figure 1, this includes the administration program of a chemotherapy composed of its drugs, their dosages, the duration of their administration (bolus vs. continuous infusion), drug properties (such as their half-life) imported from ChEBI [START_REF] Hastings | ChEBI in 2016: Improved services and an expanding collection of metabolites[END_REF] 1.

Method

In order to compare chemotherapy protocols, we propose first to learn embedding for protocols represented in ChemoKG, second to cluster similar protocols and third to compare the resulting clustering to two reference classifications: (i) protocols classified by cancer location, and (ii) by pharmacological and therapeutic subgroups.

Protocol embeddings

We propose an original approach named RAGE, standing for Relation-Aware knowledge Graph Embedding, to compute node embeddings. Inspired from relation learning in [START_REF] Monnin | Discovering alignment relations with Graph Convolutional Networks: A biomedical case study[END_REF][START_REF] Wang | Learning intents behind interactions with knowledge graph for recommendation[END_REF], RAGE builds on the GNN model to aggregate information from each entity's neighborhood, plus relations to characterize the type of links that connect the entity to its neighbors. An overview and naming of main variables involved in RAGE is depicted in Figure 2.

Let 𝒢 be a knowledge graph such as 𝒢 = {(𝑠, 𝑟, 𝑣)|𝑠, 𝑣 ∈ 𝒱, 𝑟 ∈ ℛ}, where 𝒱 is a set of nodes, here named entities, ℛ a set of labeled and oriented edges named relations or predicates and the triple (𝑠, 𝑟, 𝑣) denotes that the entity 𝑠 is related to the entity 𝑣 through the relation 𝑟 . For example, the triple (𝑐𝑖𝑠𝑝𝑙𝑎𝑡𝑖𝑛, ℎ𝑎𝑠𝐵𝑖𝑜𝑅𝑜𝑙𝑒, 𝑔𝑒𝑛𝑜𝑡𝑜𝑥𝑖𝑛) indicates that "𝑐𝑖𝑠𝑝𝑙𝑎𝑡𝑖𝑛 ℎ𝑎𝑠 𝑎 𝑏𝑖𝑜𝑙𝑜𝑔𝑖𝑐𝑎𝑙 𝑟𝑜𝑙𝑒 𝑔𝑒𝑛𝑜𝑡𝑜𝑥𝑖𝑛". The 𝑙-th layer embedding of a given entity 𝑠 is formulated as:

𝑒 𝑠 𝑙 = 1 |𝒩 𝑠 | ∑ 𝑒 𝑟 𝑙-1 ∘ 𝑒 𝑣 𝑙-1 (𝑟,𝑣)∈𝒩 𝑠 , (1)
where 𝒩 𝑠 = {(𝑟, 𝑣)|(𝑠, 𝑟, 𝑣) ∈ 𝒢} is the neighborhood of the entity 𝑠, 𝑙 = {1 … 𝐿} is the number of layers and ∘ is the element-wise product. For 𝐿 layers, the final embedding of an entity 𝑠 is defined as the sum of each layer embedding:

𝑒 𝑠 * = 𝑒 𝑠 0 + ⋯ + 𝑒 𝑠 𝐿 .
(2) Accordingly, the final embedding is the sum of embeddings from each layer including the input 𝑒 𝑑 0 . In this way, we gather all the information of the target entity 𝑠 and its "𝐿-hop" neighbors. Because our task is to perform a clustering of protocols, it is important to consider drug property in the representation of protocols. For instance, 'ATC classes' or 'biological roles' can be captured within 3-hop neighbors (Figure 1).

Given a set of protocols 𝒫 ⊂ 𝒱, the evaluation of how the relation between the protocol and a drug administration is likely is defined as follows:

𝑦 ̂𝑝𝑎 = 𝑒 𝑝 * 𝑇 𝑒 𝑎 * . ( 3
)
If the final embeddings of protocol 𝑝 and administration 𝑎 derived from (2) are close (connected) to each other the evaluation value 𝑦 ̂𝑝𝑎 is high. i.e., if the drug administration 𝑎 is part of a protocol 𝑝, 𝑦 ̂ should be high and inversely low if the drug administration is not. We define the objective function using the Bayesian personalized ranking loss [START_REF] Rendle | BPR: Bayesian personalized ranking from implicit feedback[END_REF]:

ℒ = ∑ -ln 𝜎(𝑦 ̂𝑝𝑎 -𝑦 ̂𝑝𝑎 ′ ) (𝑝,𝑎,𝑎 ′ )∈𝒮 , (4)
where 𝒮 = {(𝑝, 𝑎, 𝑎 ′ )|(𝑝, 𝑎) ∈ 𝒮 + , (𝑝, 𝑎 ′ ) ∈ 𝒮 -} and 𝜎 is the sigmoid function. 𝒮 + is the set of protocol and administered drug pair and 𝒮 -is the set of protocol and non-administered drug pair. The loss is minimized when the likely score of the administered drug increases and the likely score of the non-administered drug decreases.

Evaluation of embeddings on a link prediction task

The task of link prediction aims at predicting potentially missing links between entities within a knowledge graph, on the basis of what is already stated in the graph. To compare RAGE with other graph embedding approaches, we evaluate their different capabilities in predicting "5as Administration" predicate between protocols and drug administrations in ChemoKG. We particularly consider TransE [START_REF] Bordes | Translating embeddings for modeling multi-relational data[END_REF], DistMult [START_REF] Mikolov | Distributed representations of words and phrases and their compositionality[END_REF], MuRE [START_REF] Balazevic | Multi-relational poincaré graph embeddings[END_REF], ComplEx [START_REF] Trouillon | Complex embeddings for simple link prediction[END_REF] and CompGCN [START_REF] Vashishth | Composition-based multi-relational graph convolutional networks[END_REF]. TransE and MuRE are translational distance models that aim at finding a vector representation of entities with relation to the translation of the entities based on distance measures. DistMult and ComplEx are semantic matching models that use similarity-based scoring functions. CompGCN is a GCN-based model which considers aggregating the neighborhood information for the entity relation embeddings. The models consider the relations between entities, but require adaptation to capture similarity between strings and numerical values that compose literals or distant relations in a graph. To compare the performances of these different models, we use the Mean Reciprocal Rank (MRR) and Hits@N (H@N). MRR evaluates models that return a ranked list of answers to queries by weighting results proportionally of their place in the ranking. H@N is the count of how many positive triples are ranked in the top-N positions against a set of negative triples.

Cluster computations and evaluation

We cluster a subset of nodes 𝒫 ⊂ 𝒱 of a knowledge graph on the basis of the Euclidean distance between their embeddings computed with a selection of two embedding approaches (RAGE included). In this exploratory study we compare performances of several classical clustering algorithms, namely k-means, Single and OPTICS [START_REF] Everitt | Cluster analysis[END_REF][START_REF] Ankerst | OPTICS: Ordering points to identify the clustering structure[END_REF]. Both k-means and Single take as an input parameter the number of desired clusters. Single differs from k-means in that it is a hierarchical clustering algorithm that successively merges clusters whose distance between their closest observations is minimal. OPTICS is fundamentally different as it finds zones of high density and expands clusters from them. It takes as a main input parameter the minimal size of a cluster. We evaluate our clusters in comparison to two referential classification of protocols. The first reference classification groups protocols by their primary indication i.e., the cancer localization they primarily target according to our pharmacology experts. The second classification is based on the sets of 3 rd level ATC classes of drugs involved in protocols. These classifications are available at https://chemokg.inria.fr, for protocols of ChemoKG-open.

Clustering analyses are evaluated with Adjusted Rand Index (ARI), Normalized Mutual Information (NMI) and Fowlkes-Mallows Index (FMI). ARI measures the overlapping between two clustering (or between one and a reference classification in our case). ARI equals 0 for a random labeling and 1 for an exactly similar labeling and is adjusted to limit the effect of chance. NMI measures the mutual information between two clustering, normalized by the entropy of each clustering. NMI is equal to 1 for an exactly similar labeling. FMI is the geometric mean of precision and recall. FMI ranges from 0 to 1 and a high value indicates a high similarity between the clustering and the reference classification. In addition, we compare our method based on graph embeddings to a state-of-the-art mean to compare chemotherapies, named the Cumulative Dose Intensity (CDI) [START_REF] Longo | The calculation of actual or received dose intensity: a comparison of published methods[END_REF]. The CDI is defined as a vector of normalized cumulative doses of administered drugs. It is used to compare the course of chemotherapies, as well as protocols.

Experimental results

The experiment was conducted within two steps. First, to perceive the effectiveness of the chemotherapy protocol representation we compared RAGE with other graph embedding methods on a link prediction task on ChemoKG. Second, to seek the features and patterns within the group of chemotherapy protocols clustering was performed with the embeddings of protocols obtained from the first step. This work is implemented with PyTorch [START_REF] Paszke | Pytorch: An imperative style, high-performance deep learning library[END_REF], PyKeen [START_REF] Ali | Bringing light into the dark: A large-scale evaluation of knowledge graph embedding models under a unified framework[END_REF] for graph embeddings and scikit-learn [START_REF] Pedregosa | Scikit-learn: Machine learning in Python[END_REF] for clustering.

Graph embeddings on ChemoKG

We compared the performance of RAGE and state-of-the-art approaches on a link prediction task. 10-fold cross validation was conducted on the triples in ChemoKG. The initialization of parameters was done using Xavier uniform initialization [START_REF] Glorot | Understanding the difficulty of training deep feedforward neural networks[END_REF]. For RAGE, pre-trained vectors of entities were initialized using TransE. Next, the learning of entity embeddings is continued using the RAGE model with three layers (𝐿 = 3). The number of layers used in CompGCN was also 3. All the baseline models were optimized using Adam [START_REF] Kingma | Adam: A method for stochastic optimization[END_REF], the learning rate was 0.01 with exponential decay and the output dimension of entities was 100.

The performance of RAGE and baseline methods on the link prediction are reported in Table 2. Overall, we observed that RAGE outperformed four baselines and was competitive to MuRE on all metrics. MuRE showed the best performance for all metrics in average. We observed that translational distance models (i.e., MuRE) performed well in regard to semantic matching models (i.e., DistMult, ComplEx) and CompGCN. The performance of RAGE is relatively lower than MuRE probably because it learns relations between protocols and administrations only rather than between all the entities and relations. This observation seems to also impact clustering results reported in Section 5.2.

Chemotherapy protocol clustering

Clustering was performed on the embeddings of protocols obtained using RAGE and MuRE. Protocols assigned to the same cluster are expected to be similar in regard to their definition in ChemoKG. Results of our comparative study of three clustering algorithms and their ability to reflect our two reference classifications are shown in Table 3

Discussion and conclusion

This paper is an initial attempt to evaluate the suitability of learning graph embeddings to classify and identify similar chemotherapy protocols, in a setting where many protocols are offered to clinicians, with potentially unequal levels of evaluation, consequently generating a clinical decision-making challenge. From a knowledge representation and open resource point of view our knowledge graph is aligned with standard ontologies, but we would win in providing mapping to other initiatives, in particular HemOnc. This task is indeed not trivial as the HemOnc schema is different and less precise than ours. However, the graph embedding approach we described can spotlight highly similar protocols from HemOnc and ChemoKG, and in this sense has the potential of guiding the mapping between the two resources.

We acknowledge that the work presented here would gain from additional experiments. First, our graph of protocols encompasses some numerical values, such as drug dose and half-life. All graph embedding approaches we considered do not enable arithmetic comparisons of numerical values. This lets us think that approaches that enable such comparison, such as KEN [START_REF] Cvetkov-Iliev | Relational data embeddings for feature enrichment with background information[END_REF] would lead to improvements. Also, we experimented recursive approaches (RAGE and CompGCN) only with 𝐿 = 3 (i.e., size of the considered neighborhood), and without including inferable links in the graph. Increasing L would enable embeddings to consider more of the graph, potentially leading to improvements. The inclusion of inferable links would add direct links between drugs and higher ATC or ChEBI ontology classes, what could help in identifying similar protocols. However, this extension is associated with a risk of flooding embeddings with general classes and is consequently to test with caution. Regarding the evaluation of the clustering, we only provided external evaluation metrics, i.e., metrics that compare one clustering with a reference classification. This could be enriched with internal evaluation metrics such as the DUNN index or silhouette score that evaluate how many instances assigned to one cluster are both close to each other and distant from instances assigned to other clusters. Indeed, the two reference classifications are not a ground truth, but references one may want to compare to. In this setting, the internal quality of the clustering is a pertinent metrics, which could also enable the comparison of various clustering strategies.

Nonetheless, our experiments illustrate the level of performance of various graph embedding approaches on ChemoKG and their usability for learning meaningful clusters. We will pursue our efforts to facilitate the data and knowledge management associated with chemotherapy protocols and would like to expand our work from protocols to patient data, and study how protocols are respected, or modified to adapt to individuals and what is the impact on patient outcomes.

Contributions

JHJ populated ChemoOnto with protocols, enriched it with additional drug properties; codesigned the study; designed RAGE; implemented and ran the experiments; wrote the first version of this manuscript. AR created ChemoOnto and designed the instantiation of ChemoOnto with protocols; participated in the writing. DG, EP and BS guided the motivation of the work, provided with the two reference classifications. BR participated in the design of ChemoOnto, ChemKG and of this study, and in the writing. AC participated in the design of ChemoOnto, ChemKG, co-designed this study, and contributed to the writing.

Figure 1 :

 1 Figure 1: Sample from ChemoKG. The central entity is a protocol (in red), with two drug administrations (in green), each associated with its drug (in grey). Arrows describe a relation type from one entity to another. 'Dose', 'half life', 'bolus' are literals.

Figure 2 :

 2 Figure 2: Overview of the relation-aware aggregation scheme in RAGE. 𝑝 is the node we learn final embedding for, here a protocol. 𝑎 and 𝑎' are nodes related and not related to 𝑝 , respectively; here drug administrations. 𝑣 𝑖 are other nodes of the graph. 𝑟 𝑖 are predicates relating nodes. Plus signs represent the aggregative sum of embeddings. 𝑦 ̂𝑝𝑎 is an evaluation of the probability for nodes 𝑝 and 𝑎 to be linked.

  , DrugBank and their classification in the ATC classification. The protocols themselves have been extracted from a local database of the Pharmacy Service of the European Georges Pompidou Hospital of the AP-HP, Paris. The resulting knowledge graph encompasses 329,164 triples with 99,901 entities and 75 relations including 1,358 chemotherapy protocols and 226 anti-cancer drugs. ChemoKG includes both protocols used in standard treatments and in clinical studies. Because protocols evaluated by clinical studies are confidential, we defined a subset of our knowledge graph named ChemoKG-open that excludes them and that is consequently sharable. The statistics of the main classes of ChemoKG and ChemoKG-open are presented in Table

	ChemoKG-open	includes	513	protocols	and	is	available	on	Zenodo	at
	https://zenodo.org/records/10263831. 1

Table 1 Statistics of entities in ChemoKG and ChemoKG-open

 1

	Class	# entities (ChemoKG)	# entities (ChemoKG-open)	Source
	Protocol	1,358	513	ChemoOnto
	Anti-cancer drug	226	82	ChemoOnto
	Bolus (True/False)	2	2	ChemoOnto
	Dose	119	71	ChemoOnto
	ATC	6,691	6,691	ATC
	Biological role	13,286	13,286	ChEBI
	Half-life	81	81	DrugBank

Table 2 Performance of various considered models for the task of link prediction on ChemoKG.

 2

	Model	MRR	H@1	H@3	H@10
	TransE [12]	0.1445±0.1340	0.0866±0.0610	0.2263±0.1152	0.3247±0.1759
	DistMult [14]	0.2187±0.2182	0.1874±0.1874	0.2430±0.1333	0.2662±0.1239
	ComplEx [15]	0.1064±0.0876	0.0730±0.0163	0.1013±0.0632	0.1402±0.0966
	MuRE [16]	0.3771±0.1632	0.3402±0.1307	0.4688±0.1221	0.5345±0.1424
	CompGCN [35]	0.3018±0.1485	0.1546±0.1542	0.4083±0.1918	0.4958±0.1625
	RAGE [proposed method]	0.3538±0.1899	0.3307±0.1618	0.4538±0.2065	0.5116±0.1876

  and 4. For cancer locations, RAGE and the combination of CDI and RAGE showed better performance than CDI alone and MuRE. For ATC, RAGE still showed better performance than CDI and MuRE. We deduce that drug properties such as biological roles and half-lifes were beneficial for grouping protocols into cancer locations, which are absent from the graph. The ATC level information present in ChemoKG should be considered by RAGE what should explain the good grouping of protocols according to ATC classes.

Table 3 Performance of protocol clustering in comparison with a reference classification based on their primary indication (i.e., cancer locations). Parameter K is the number of clusters and S the minimum size of clusters.

 3

			CDI			MuRE			RAGE			CDI+RAGE
		ARI	NMI	FMI	ARI	NMI	FMI	ARI	NMI	FMI	ARI	NMI	FMI
	K-means (K=32) 0.1045	0.4127	0.1553	0.0581	0.3484	0.1074	0.4266	0.7150	0.4783	0.3508	0.7135	0.4059
	Single (K=32)	0.0429	0.3538	0.1924	0.0021	0.1730	0.2384	0.6153	0.7706	0.6433	0.7628	0.8106	0.7862
	OPTICS (S=20)	0.0183	0.2198	0.1467	0.0046	0.1723	0.1138	0.4946	0.7314	0.5706	0.4402	0.6896	0.5444

Table 4 Performance of protocol clustering in comparison with a reference classification based on the pharmaceutical class of their drugs. Parameter K is the number of clusters and S the minimum size of clusters.

 4

			CDI			MuRE			RAGE			CDI+RAGE
		ARI	NMI	FMI	ARI	NMI	FMI	ARI	NMI	FMI	ARI	NMI	FMI
	K-means (K=10) 0.1204	0.2156	0.2326	0.0741	0.1939	0.1891	0.8420	0.9336	0.8651	0.8281	0.9311	0.8542
	Single (K=10)	0.0872	0.2419	0.3007	0.0059	0.0751	0.3717	0.9509	0.9687	0.9591	0.8071	0.9355	0.8503
	OPTICS (S=20)	0.0436	0.1811	0.2466	0.0167	0.0438	0.3441	0.7157	0.8662	0.7557	0.5885	0.8126	0.6546

A SPARQL endpoint will be made available upon publication at https://chemokg.inria.fr.

Acknowledgements

This work is supported by Inria Paris and the CombO project. This work has benefited from a government grant managed by the Agence Nationale de la Recherche under the France 2030 program, reference ANR-22-PESN-0007, ShareFAIR and ANR-22-PESN-0008, NEUROVASC.


Institut de Démographie de l'Université Paris1

Auteurs : DEJOUX Virginie virginie.dejoux@inrets.fr ALAUZET Aline aline.alauzet@inrets.fr ARMOOGUM Jimmy jimmy.armoogum@inrets.fr no difficulties 55% 5% 5% 15% 20%

The mobility of people with travel disabilities: impact of personal characteristics on reporting difficulties

Context

In a context of demographic and social changes, such as the ageing of population and the disappearance of local services, the number of persons who find it difficult to move around unassisted outside their home increases. About 10 % of the population have difficulties when they are making trips.

Objectives

The goal of this research is to discover which individuals find themselves in disability situations and to identify their travel behaviors.

Methodology

• Data : This research is based on the HID data (Handicaps-Incapacités-Dépendance, Disability-Activity limitations-Dependency). This survey was conducted in France in 1999, by the French national institute of statistics.

The respondent sample size of the survey was about 17 000 households.

• Population selection: A disability situation arises from a reduction in the ability to carry out day-to-day activities caused by the interaction between personal factors (impairments, activity limitations and other personal characteristics) and environmental factors. So we have identified the persons who are in disability situations when they travel according to the difficulties they report.

Difficulties increase with age

The percentage of persons reporting travel difficulties increases with age.

While in the youngest age groups (under 60 year-olds) less than 9 % of individuals report difficulties, the figure for the 60-79 year-olds is 24.9% and for the over 80 year-olds, 59.2%.

Also, over the age of 60, a non-negligible percentage of the population experienced the most sever difficulties.

Different transport modes used by persons with and without travel difficulties

First, persons with difficulties seem to travel more on foot or in a wheel chair that those without: 33% of the trips made by persons with difficulties compared with 20% for persons without.

Furthermore, even though cars accounted for a smaller percentage of all the trips made by persons with difficulties, the percentage of their trips in which they were car passengers was higher.

Fewer trips for people affected

Persons in a disability travel less than persons who report no difficulties

Greater immobility

The more the level of difficulties is high the more the share of people staying at home is high

Conclusion

As disability situations are nowadays defined as a conflict between personal factors and environmental factors, the HID survey has allowed us to enumerate and characterize persons in disability situations during their journeys based on their responses to the question about their travel difficulties.

A number of socio-demographic characteristics affect travel difficulties, in particular older people.

Finally, persons in a disability situation travel less and use different modes than persons who report no difficulties.

Gender influences the disability situation

60.4% of the individuals in a disability situation for their mobility are women, while women account for only 50.6% of the individuals who experienced no difficulties.

Breakdown of the main transport modes used by people with and without travel difficulties

of difficulties Gender of people with difficulties

	male 40%	60% Level female	No difficulties	Simple difficulties	limited on some routes	limited on all routes
		Average number of trips per person per day	1,3	1,0	0,8	0,4
	Level

of difficulties reported by age group

	70
	60
	50
	40			lim ited on all routes
	%			lim ited on s om e routes
	30			s im ple difficulties
	20
	10
	0
	0-19	20-39	40-59	60-79 80 and +
			age band

Percentage of people who stay at home the reporting day according to the level of reported difficulties

	100
	80
	60
	40
	20
	0
	no difficulties	simple	limited on	limited on all
			some routes	routes