Sascha Diwersy

Francesca Frontini

Giancarlo Luxardo

The Parliamentary Debates as a Resource for the Textometric Study of the French Political Discourse

Keywords: political discourse, parliamentary corpora, metadata

This paper reports on a corpus collecting together the French parliamentary debates in plenary sitting. It outlines the design and data format of the samples and presents various usage scenarios related to their textometric use.

Introduction

This contribution presents a corpus that contains the transcriptions of French parliamentary debates; we also discuss the possibilities of its exploration from a textometric perspective. The paper is structured as follows. Section 2 outlines the rationale behind the creation of the corpus, its composition and the concepts involved in its design. Section 3 describes how the corpus can be processed to be implemented in a publishing platform. In section 4, we then introduce some key elements of a textometric methodology and illustrate the exploration of the corpus by giving brief sketches of corresponding usage scenarios. Section 5 provides a summary and discusses possible directions for future developments of the resource presented in this paper.

The TAPS-fr corpus

Rationale and composition of TAPS-fr

The Assemblée Nationale publishes on an open access basis1 a number of datasets, and among them its debates in plenary sitting, dating back to 2013 and provided as a regularly updated data dump at http://data.assemblee-nationale.fr/ travaux-parlementaires/debats.2 . The textual data have been processed and assembled according to a methodology discussed in the following and called Transcription and Annotation of Parliamentary Speech (TAPS), with the aim of offering a large-scale resource to researchers working on French political discourse, especially from a data-driven perspective. The methodology is kept as generic as possible, in order to be reused for debates of additional parliaments, possibly in other languages. We call the corpus described here TAPS-fr. It is primarily designed to provide a methodological support for investigations in the French tradition of textometry (French: textométrie), which integrates both searches based on full-text indexing and multivariate exploratory data analysis [START_REF] Lebart | Exploring Textual Data, volume 4 of Text, Speech and Language Technology[END_REF]. The open data publishing of the French parliamentary debates is part of a trend known as Open Government Data and described with the eight principles defined by the Sebastopol meeting held in 20073 . One of the challenges for the projects initiated in this trend is set by the fact that these open data, while published in large amounts and accessible with a relative ease of reuse, are "raw data": little is known about the conditions of their production [START_REF] Plancq | Utiliser les données ouvertes (open data). Un exemple avec les débats en séance publique à l'Assemblée nationale[END_REF]. We subdivided the TAPS-fr corpus into three subcorpora described by Table 1: 1. The first months (May 2013 -December 2013) represent a small subcorpus, which was not processed in depth so far (the source webpage states that the debates were fully transcribed only from October 2013).

2. The second subcorpus was the one mostly used for our experiments: it comprises the debates of the last months of the 14th legislature (January 2014 -February 2017).

3. A third corpus includes the debates of the 15th legislature up to the end of December 2017.

A machine-processable format geared to multiple needs

We distinguish four formats handled for the processing of TAPS-fr, all of them being XML-based:

1. The source format: it is the format used by the raw data, which is subdivided in three components (actors, bodies -organes -and sittings); the text is included in the sittings section and refers to actors (members of parliament, members of government, etc.) belonging to various bodies (e.g. parliamentary commissions).

2. The TAPS format: it is the result of a conversion applied to the source data, in order to extract the relevant metadata and annotation useful to our applications (see below).

3. The XML-TXM format is a customization of the TEI data model used by the TXM software as a pivot format in order to present semantic and editorial annotations.

4. The CWB format (defined by the IMS Open Corpus Workbench) encapsulates lexical and syntactic annotations and is used by a search engine, allowing text retrieval based on queries expressed in the CQP (Corpus Query Processor) syntax. This is a compound format with XML tags and token records appearing on separate lines (one surface form is associated to tabdelimited token-level annotations).

The descriptions of the TXM (for "textometry") platform [START_REF] Lavrentiev | Analyzing TEI encoded texts with the TXM platform[END_REF] and of the CWB environment (Evert and Hardie, 2011) are beyond the scope of the present document. However, the following two sections describe how they have been implemented in this project.

The TAPS format basically relies on the concepts of metadata and annotations defined in the TXM environment, which distinguishes structural units and lexical units. Metadata (the association of a variable and a set of modalities) are used to partition the corpus, to create subcorpora and to retrieve the text. They are defined on various structural units: XML elements, text segments, paragraphs, sentences, and possibly other units defined by the user. Metadata are therefore viewed as properties of structural units. Each processed lexical unit has several properties, such as word form, lemma and part-of-speech (grammatical category).

The conversion from the source format to the TAPS format creates a number of files, each one associated to a parliamentary sitting. The metadata that is extracted from the source format can be associated either globally to each file or to a single speech (the intervention of a person in the debate). The format of the files complies with the TEI data model, so that the metadata associated to a file are described in the TEI header. For the single speech, the <u> element (utterance) was chosen4 : this element is originally defined by the TEI guidelines for the transcription of oral corpora, it is extended by the definition of a number of attributes relevant to our application (e.g.: role in the debate, nomination in the parliamentary structures, nomination in the government, political affiliation...). The assignment of attributes at the utterance level and within the TEI headers implies some redundancy, however it provides an easier reuse for the text retrieval. [START_REF] Schmid | Probabilistic part-of-speech tagging using decision trees[END_REF], it is possible to pre-process the corpus data outside the platform by using other NLP toolkits. In our specific case, we chose the freely available processing pipeline Bonsai8 (Candito et al., 2010b;Candito et al., 2010a) in order to add syntactic dependency annotations. The latter have been extended by several categories whose purpose is to optimize the processing of queries exploring the dependency relations annotated in the corpus. The categories in question are marked by an asterisk in Table 3, which outlines the overall data model of the word level annotations within the TAPS-fr corpus.

The publishing framework

The four formats described in section 2.2 enable to publish the TAPS-fr corpus in two different contexts: either within the TXM interface or in the TAPS format for the purpose of improving interoperability. Both options provide some conformance level with the TEI guidelines. i.e. a formatted output presented alongside a facsimile (e.g. a manuscript), is provided by the use of the TEI guidelines.

The TXM conformance to TEI is implemented through the use of the TXM pivot format (XML-TXM 9 ), which is basically derived from the need to generate a document to be rendered in a browser (with specific layout directives), while allowing the navigation in the text through the support of the TEI <w> element (which encapsulates morphosyntactic and other annotations of the words).

In the context of TAPS-fr, as a parliamentary corpus, the basic requirement is to provide a single edition allowing navigation in a browser and keeping the editorial annotations made by the transcribers. Possible extensions would be to provide multiple editions including: the translation to a different language (but this usage would be unlikely in the case of the Assemblée Nationale) or links to audio or video recording.

The TAPS-fr corpus is available from the textometry portal of the Praxiling laboratory 10 , either directly browsable online in the TXM environment or as a downloadable resource (with the possibility to process it offline in the desktop version of the TXM software).

In order to comply with the TEI model, the TAPS sitting files (already mentioned above) contain a TEIheader: apart from the information related to the publication conditions (<fileDesc>), this header also describes the date of the sitting and the speakers involved (<creation> element in <profileDesc>).

9 In addition to the generic XML format, TXM also integrates TEI with an import module, called TXM-XTZ (XML TEI Zero), which is able to interpret the semantics associated to a minimal set of TEI elements, through the application of XSL stylesheets.

10 http://textometrie.univ-montp3.fr/

The analytical framework

In this section we will briefly illustrate the application of two standard methods in textometry -correspondence analysis (CA) and the identification of characteristic items by frequency specificities -to the TAPS-fr corpus. Correspondence analysis (cf. [START_REF] Benzécri | L'analyse des données : L'analyse des correspondances[END_REF], (Lebart et al., 1998, 45ssq)) is a useful technique in providing a condensed view of divergences relating to samples (resulting from a partition in the corpus) and lexical items.

We illustrate this by means of a plot generated on the basis of a CA (Figure 1) 11 performed on the speeches in the second subcorpus (cf. section 2) using the political group of each speaker (excluding the sitting presidents and the members of government) as differentiating variable. It is possible to observe that the first (horizontal) axis opposes the right-wing groups (UMP-LR, UDI), which have negative coordinates, to the left-wing groups (SRC-SER, Écolo, RRDP, GDR), which are located on the positive side, whereas on the second (vertical) axis, the socialist group (SRC-SER), which forms the major part of the government majority during that period, stands in contrast to the group of left-wing opposition parties GDR.

An efficient way to single out the lexical (and grammatical) items implicated in the opposition of extralinguistic factors highlighted by CA is the computation of frequency specificities based on the hypergeometric distribution [START_REF] Lafon | Sur la variabilité de la fréquence des formes dans un corpus[END_REF], a lexico-statistical approach similar to the keyword analysis used in the British tradition of corpus linguistics (cf. amongst others [START_REF] Rayson | Matrix:a statistical method and software tool for linguistic analysis through corpus comparison[END_REF]). Figure 2 highlights some of the nouns that are more specific to the discourse of the right-wing parliamentary group UMP-LR. These include nouns referring to the nation (Franc ¸ais 'French') and other classic elements of conservative ideology both in social (e.g. the series famille 'family', parent 'parent', enfant 'child') and economic terms (e.g. nouns designating learned professions such as médecin 'doctor, physician', notaire 'notary, solicitor').

Conclusion and outlook

In this paper, we introduced TAPS-fr, a corpus of debates from the Assemblée Nationale by giving a brief sketch of the methodology underlying its creation, of its data model and of some application scenarios that illustrate the exploitation of this resource within the analytical framework of textomtry. The corpus, whose preliminary version is now accessible at http://textometrie. univ-montp3.fr/, will be published in its stable version in the Ortolang 12 CLARIN repository for long term preservation, under the CC BY-NC 4.0 license. As the TAPS-fr is meant to be a monitor corpus 13 , it will continually be expanded on the basis of the regularly updated raw 11 The CA plot was generated by means of the R packages Fac-toMineR [START_REF] Husson | Fac-toMineR: Multivariate Exploratory Data Analysis and Data Mining with R[END_REF] and explor [START_REF] Barnier | explor: Interactive Interfaces for Results Exploration[END_REF]. We have chosen these packages instead of TXM's CA command because they allow for a more flexible manipulation of the graphical output. The axis descriptions indicated by the horizontal and vertical arrows have been added in a post-processing step.

12 https://www.ortolang.fr/ 13 For the notion of monitor corpus see amongst others (McEnery and Hardie, 2011, 6sq.). vice, but we also intend to include successively samples of parliamentary sessions prior to 2013. In the latter case, this implies the necessity to adapt our current approach to the processing of material coming from various source formats (primarily HTML and XML with different schema specifications) with varying granularity of directly retrievable information, which might lead to slight revisions of the data model presented in this paper. The future stabilization of our methodology could lay ground not only to the continuous construction of a resource providing broad coverage of the debates at the French Assemblée Nationale, but also to the project of creating an extended textual base, which by integrating the plenary sessions of the Sénat, the second chamber of the French Parliament, would constitute a large scale corpus of institutional and political discourse in contemporary France at the national level.

Figure 1 :

 1 Figure 1: CA plot based on a partition by political group (word-rows are not displayed). Point sizes indicate contribution.

Figure 2 :

 2 Figure 2: Most characteristic nouns specific to the discourse of the parliamentary group UMP-LR

Table 1 :

 1 Composition of the TAPS-fr

	Legislature Period	Nr of sessions Nr of words
	14	05/13-12/13	152	5,200 K
	14	01/14-02/17	873	28,600 K
	15	06/17-12/17	156	4,700 K
	Total			38,500 K

Table 2 :

 2 Table 2 specifies the major structural units defined within the data model of the TAPS-fr corpus. Main structural units encoded in the TAPS-fr corpus Starting from the TAPS format, the TXM environment performs several steps of conversion and generates files in the XML-TXM format as well as in the CWB format, which, in both cases, can include linguistic annotations added to the lexical units. While TXM's import modules allow for automatic morphosyntactic tagging and lemmatisation by means of TreeTagger 7

	Structural	Associated Metadata	XML Element
	Unit	(descriptors)
	sitting	date-time, year, par-	<text>
		liamentary term
	speech	speaker	name,	<u> (utterance)
		speaker role, par-
		liamentary	group,
		speech type (debate,
		interruption,	vote
		explanation, etc.) 5
	paralinguistic event sentence 6	description -		<incident>

<s>

Table 3 :

 3 Linguistic annotations at the word level for textual criticism. The ability to produce a critical edition of a historical source, typically a "synoptic edition".

	Unlike older software tools developed within the French
	community of "analyse des données textuelles" (textual
	data analysis), TXM was designed to support applications

The "Licence ouverte / Open Licence" is a free licence created by the French governmental mission Etalab.

2 A selection of parliamentary records from the Assemblée Nationale has already been collected and published in TEI format in[START_REF] Truan | Débats parlementaires sur l'europe à l'assemblée nationale (2002-2012)[END_REF] as part of a broader project on perceptions of the other in various European countries.

https://opengovdata.org/

This approach was also adopted by[START_REF] Truan | Débats parlementaires sur l'europe à l'assemblée nationale (2002-2012)[END_REF] and by the authors of the SlovParl corpus(Pančur et al., 2017), whereas earlier versions of the latter opted for the <sp> element defined by the TEI module for encoding performance texts (cf. https: //github.com/SIstory/SlovParl).

From a linguistic point of view, this descriptor, which is not included in the data model of the corpus provided by[START_REF] Truan | Débats parlementaires sur l'europe à l'assemblée nationale (2002-2012)[END_REF], is particularly important when it comes to differentiate effects of register variation ranging from highly formulaic to less formal speech (as in the case of e.g. interruptions). It should be noted that this metadata element can be easily retrieved from the raw data dump we used to build the TAPS-fr corpus, whereas it is only partially or not all available in the other source formats (HTML or pdf) used by the Assemblée Nationale to publish its minutes on-line.

6 This unit is optional as it is only provided in the case of specific processing steps pertaining to linguistic

annotation. 7 http://www.cis.uni-muenchen.de/ ˜schmid/

tools/TreeTagger/ 8 https://alpage.inria.fr/statgram/frdep/ fr_stat_dep_parsing.html


Jérémy Dehors

Bruno Gügi

Alain Mareck

Patrice Lerouge

Arnaud Lehner

Jean-Claude Mollet

Deciphering the links between ROS, Ca 2+ and cell wall remodeling during Arabidopsis thaliana pollen tube growth

Introduction

Pollen tube : A model for cell growth and cell wall remodelling Pollen cell wall must resist turgor pressure and allow fast and continuous growth, which involves fine tuning and remodelling of cell wall components.

Figure 1 : Pollen tube morphology, with a single cell wall layer in the apicale zone (blue) and a bilayer wall on the shank (red) that ensure apical growth while keeping the cylinder shape of the tube. G : Golgi apparatus, CW : Cell Wall, 1 : Outer layer (pectins, XyG and cellulose), 2 : Inner layer (callose and cellulose). [START_REF] Dardelle | Biochemical and Immunocytological Characterizations of Arabidopsis Pollen Tube Cell Wall[END_REF] Figure 2 : Calcium is highly concentrated at the apex and oscillates in time to permit polarized growth [START_REF] Cárdenas | Pollen Tube Growth Oscillations and Intracellular Calcium Levels Are Reversibly Modulated by Actin Polymerization[END_REF]. Demethylation of cell wall pectins (Figure 7A) has a huge impact on its properties, moduling the plasticity needed for anisotropic growth

Objectives

Cell wall charecterization

Results

Inhibition of ROS production leads to a decrease of the degree of methylesterification (DM) at the tip (Figure 8) LaCl leads to a degradation of the cell wall all along the tube, Fragments of pectin and xyloglucan are detectable in the culture medium (Figure 8

Figure 3 :

 3 Figure 3 : Phenotype of pollen tubes after 6 hours of culture. A) Mock in liquid culture medium, B) DPI-supplemented medium (25µM), C) Lanthanum chloride-supplemented medium (50µM ). Arrows indicate burst of pollen tubes

Figure 7 :

 7 Figure 7 : Representation of the two mains cell wall components : (A) the pectin homogalacturonan with its demethylation process (from Micheli (2001)), and (B) xyloglucan (adapted from Del Bem & Vincentz (2010)).

  Figure 8 : Immuno-detection of cell wall associated epitopes. (A,B,C) LM20, (D,E,F) LM19, (G,H,I) LM25, under control conditions and DPI or LaCl treatment. (HM = Highly methylesterified, WM = Weakly methylesterified).

Figure 9 :

 9 Figure 9 : Intensity of callose detection in the pollen shank for Mock, DPI-treated and LaCl-treated pollen tubes.

Figure 10 :

 10 Figure 10 : SEM of LaCl-treated tubes shows small particles on the cell wall, similar to those seen in immunolabelling, which are absent on the Mock tube. These particles are supposed to be cell wall fragments which are peeling o the tube (indicated with arrows).

  and 10) ROS and Ca 2+ pathway

Figure 11 :

 11 Figure 11 : NBT staining shows ROS at the apex of mock tubes (A) and LaCl treated pollen tube (C). The absence of ROS when treated with DPI (B) and cotreated with both DPI and LaCl (D) confirm that LaCl reversion of pollen tube phenotype does not involve a reactivation of NADPH oxidases by the alteration of calcium fluxes.

Figure 12 :Figure 13 :Figure 14 :

 121314 Figure 12 : Actions and interaction of ROS and Calcium and their impact on pollen tube growth.

Table 1 :

 1 List of the different chemicals used and their e ects.

	Chemical	Biological e ect
	Methylviologen	ROS inductor
	DPI	NADPHox (ROS producing) Inhibitor
	Nitroarginine	NOS (NO producing) inhibitor
	Sodium benzoate	ROS scavenger
	Lanthanum chloride Calcium channels blocker
	EGTA	Calcium chelator
	Nitroprusside sodium NO inductor
	cPTIO	NO inhibitor
	Sildenafil citrate	cGMP-specific phosphodiesterase inhibitor


El-Hadi Khoumeri

Jean-François Santucci

Dominique Federici
email: federici@univ-corse.fr

Hierarchical multi-view representation of spatial data; application to the analysis of Corsican Neolithic tombs

Introduction

Starting from a joint project undertaken at the University of Corsica between computer sciences researchers, anthropologists and astronomers we deal in this article with the problem of the definition of the concepts of abstraction levels and views of spatial data for analyzing archeological data. This interdisciplinary project begins with a first research work concerning in particular :

• The GPS localization of Neolithic sites and toponyms in the Corsica Island.

• GIS representation of the previous data through spatial entities

• Analysis of the previous spatial entities described at various abstraction levels.

This first work enabled us to highlight a set of problems when dealing with data coming from the following domains: archaeology, anthropology and astronomy. The solution that we propose for solving the previous problems rests on a definition of abstraction levels for spatial data, as well as the definition of automatic transfer functions between abstraction levels.The implementation of the solution has been carried out using an oriented object design.

We present in detail in this article how the definition of the concepts of levels of abstraction and of transfer functions allows the resolution of problems previously highlighted.

Moreover we point out how starting from these concepts we can offer a generic software infrastructure allowing in particular:

• To manage several levels of abstraction,

• To define or use transfer functions between levels,

• To carry out geometrical or astronomical analysis between various spatial archeological data.

The generic software infrastructure is developed in Visual BASIC because this language facilitates on the one hand the implementation of the various concepts and on the other hand the integration of these concepts in a GIS.

The validation of the software is carried out within the framework of the interdisciplinary project : in a last part of the paper we present how using the previous generic software we have been able to analyze how legends, megaliths and astronomy are linked in the Nebbiu Region in the north part of Corsica..

Problems

Context of the study

The study presented in this article belongs to a set of work concerning the use of the GIS in archaeology. In our case the context of the study is the following : by taking a mix of data from natural and cultural inheritance, the general objective is to offer a powerful software tool for archeologists or anthropologists. This tool should be "open" in the way that it has to offer possibilities, which can comply with complex requests. This gives the researcher all freedom to correlate information. As we will see it below the archeoastronomy rests on studies coming from three distinct fields: archaeology, anthropology and astronomy. Indeed, space is for a society of orality the receptacle of all the inscriptions of it's past, its stories and its beliefs. The toponym allows for the restoration of the awareness of gestures, sounds, the resonance of the place, its values and its properties, supplemented and perpetuated with past generations.

The goal is to work at the interface between the preceding fields in order to try out the capacities of the GIS to being used in the context of a research in archeoastronomy. Archeoastronomy [1] is the science which relates to the discovery and the study of beliefs and the astronomical practices of the ancient societies; it is initially a tool to include/understand the intellectual achievements of the primitive cultures, such as for example, the builders of megalithic alignments. In order to help archeoastronomers from a point of view of software tools, we have to facilitate the following analysis using GIS: (i) simulate the sky of the ancient people and to calculate the suitable ephemeredes, to then be confronted with oral saves (reconstitution sources of celestial phenomena by the simulation of the aspect of the sky at one time and with a given place); (ii) to establish geometrical links between the different sites, (iii) to study the bonds between toponym and interesting sites from a point of view of archeoastronomy.

The goal is to be able to help the archeoastronomists to define following information in a GIS :

• GPS localizations of menhirs and dolmens

• Abstractions of this information (for example a point represents an alignment of menhirs) Hiérarchie données SIG archéoastronomie

• It must possible to carry out geometrical and astronomical analysis.

Basic concepts: concepts of domains and levels of abstraction

After an analysis of the capacities of the GIS for researches undertaken in archeology we identified the following problems to be solved from a computer science point of view :

• Difficulty of representing information about space at various levels of abstraction

• Difficulty of representing information about space, corresponding to various points of view of localization

• Difficulty of connecting information about space in a geometrical way

• Difficulty to deduce and of represent data resulting from an astronomy point of view on a GIS.

In order to propose a solution for solving the four previous highlighted problems we developed the concept of levels of abstraction and the concept of domain of spatial data.

A spatial zone will therefore have to be able to be visualized according to various points of view (domains) and at different levels of abstraction : several spatial representations could be associated at a spatial zone. In our study we represent a spatial object as being an elementary spatial ele to a representation of a given domain and to a given level of abstraction.

The translation of a representation towards representations more (less) detailed requires the definition of transfer functions of information making possible the automatic generation of a new representation more (less) detailed.

For the same domain, the generation of a representation from a level of abstraction N towards a level of abstraction higher N-1 is named aggregation. The opposite generation is named decomposition. The transfer functions describe how aggregation and the decomposition must be carried out. They are defined by the user or by default in the software system that we propose to create, we can quote like example of transfer function the algorithms of generalization [RUA 99] and [BED 02].

Implémentation des concepts en VB

The concepts presented in part 3 are validating by the realization of a prototype of a software called Gis-Archeo-Astro developed in Visual BASIC. We chose to validate the previous concepts using the language Visual BASIC (VB) for two main reasons : (i) the integration of the concepts in the GIS Arcview is facilitated by the use of VB since the personalization of Arcview rests on the use of VBA (Visual BASIC Application) ; (ii) the use of VB completely meets the requirement in terms of the ergonomic features associated with the development for interfaces dedicated to not-data processing specialists such as archaeologists or anthropologists.

We highlight in this part how a user interested by the three fields (archaeology, astronomy, anthropology) will be able to define without problem the representations of the same spatial zone according to 3 different fields at different levels of abstraction. Moreover it will be able to visualize and of course to generate a representation from another for a given field.

In the examples which follows the concepts of multi-windowing, the functions of geometrical tracing and astronomical calculations are not illustrated for preoccupations with a clearness of presentation. However these concepts are completely integrated into the Gis-Archeo-Astro software which we implemented.

The validation was carried out starting from a concrete example concerning the archaeological sites of Monte Revincu.

We have to point out that the megalithic Corsican civilization flourished in the first half of the fourth millennium B.C. This early phase has left numerous traces in Corsica that are to be found everywhere in the southern half of the island and in some very few parts in the northern part (Nebbiu region). As regards burials, there seems in megalithic times to have been the same orientation custom all over the island. The site of Monte Revincu is located in the area of Agriate at the North of Corsica. The landscape is contrasted enough here, it is composed of small narrow valleys or broad depressions. Figure 1 highlights the landscape in 3D as well as the 3 funerary sites of Monte Revincu (called Lurcu, Orca and Monte Revincu). Each one as of the 3 sites is him even made up of one or more megalithic tombs. of abstraction. We see on figure 2 that the first representation R1 is made up of a space entity of type node (coordinated X and y) and models an archaeological complex. However in order to be able to study this archeological complex we need a more detailed view of the complex (level 2). For that , the user will be able by using the decomposition to generate the representation R2 given of figure 3 (level 2, archaeology field) made up of three space entities of type node. These three points can be broken up on a lower level (level 3) in order to study the types of structures composing each one of these sites (dolmens or non-dolmenic tombs). Of course the user can if it wishes it to refine the level of detail by generating the Hiérarchie données SIG archéoastronomie representation R3 (level 3, archaeology field) starting from the representation R2 by clicking on the button «Down ». Figure 4 illustrates this decomposition. The user can also carry out an automatic passage of the representation R2 towards the representation R1 by using aggregation (button «Up "). The passage between levels is carried out using transfer functions.

These transfer functions are defined by the users .

Figure 2 : Localisation of Monte Revincu (Représentation R1)

We must moreover note that the sites at the highest level are indicated by a red point, on level 2 by squares red (see figure 3).

Finally on the level 3 several types of points are available corresponding to dolmens or non-dolmenic tombs. The dolmens are located by a red symbol pointing out the shape of a dolmen while the non-dolmenic tombs are represented by a blue symbol having the shape of such a tomb.

Orientations of the megaliths

Some aspects of methodology

Our task in this section is to report the orientations that the builders selected for the megaliths of Monte Revincu. We define these orientations to be the azimuths of the principal axis of the rectangular chamber of the measured tombs, in the direction from the closed end to the entrance. These directions (azimuths) were measured in June 2004 with compasses whose errors had already been established. In the case of dolmens there is no doubt that the relevant direction is from the interior towards the entrance [3]. However we have to precise our choice about the cists because the decision about which of the two directions of the principal axis of the cist becomes important. In the course of our fieldwork we also measured a number of additional non-dolmenic early tombs and the relevant data are also listed in sub-section 4.2. In this case we choose the direction which seems to be the most obvious for us.

If and this is no more than a possibility the intention of the builders was astronomical and the megalithic sepulchres were constructed to face the setting or rising points of celestial objects, then angular altitude of the skyline must of course be taken into account when we calculate the declinations corresponding to these azimuths. The angular altitude has been measured with a hand-held clinometer.

A third datum is needed for an astronomical interpretation : the latitude of the studied site. The use of a GPS is very useful for obtaining this last datum.

Given azimuth, angular altitude of the skyline, and latitude, the corresponding astronomical declination is easily found from a simple trigonometrical formula. In our case we used a computer program developed by C. Ruggles at the University of Leicester,England and which can be obtained using the web [17].

Our measurements of the dolmens and early non-dolmenic tombs (azimuth, angular altitude, latitude and corresponding declination) are set out in the next sub-section.

Orientations of the dolmens involved in Monte Revincu

In our fieldwork we came across the measurements of the three dolmens and four early non-dolmenic tombs (cists) listed in section 4.. Their orientations are listed in Table 1 andTable 2. We have to point out that the dolmens 'Casa di u Lurcu' Hiérarchie données SIG archéoastronomie (Lurcu dolmen) 'Casa di l'Orca' (Orca dolmen) and involved two orientations because it has a clear defined entrance but also a clear defined passage with a different orientation. Once the data have been collected, the first question we have to answer is whether the previous collected orientations fall within a range. After this first analysis we have consider whether or not the motivation originated in the sky or whether it was terrestrial or even meteorological.

Orientations Analysis

In this sub-section we detail that although we are dealing only with 7 monuments and nine orientations, it is most unlikely that their orientations would be so similar purely by chance, and the GIS nature in azimuth must result from some astronomical intention on the part of the builders.

From the two tables we can see that the azimuth are highly non random (from 60° to 130°) measures about 1/6 th of a circle (see figure 5). Such a concentration of axes cannot have come about by chance.

Furthermore the declination of the tables 1 and 2 show that all the nine orientations are in the correct range to face the rising sun or moon. The declinations are showed in figure 6 through an histogram pointed out clearly that all the declinations correspond to the rising of the sun or the moon.

We point out in this article that the orientations of the great majority of these dolmens confirm the conclusions already • SR (sun rising) :characterization of tombs having orientations within the range 60-130° or thereabouts.

• SR/SC (sun rising/ climbing) :characterization of tombs having a wider range , from 60° to due south or thereabouts,

• SS (sun setting) : characterization of tmbs facing the western half og the horizn within a range 240°-300°,

• SD/SS (sun descending-setting) : characterization of tombs having a wider range from due south to 300°.

The seven megalithic sepulchres of the Nebbiu region we investigated face roughly between north east and south east ; more exactly between azimuth 60° and 130° .

We already point out that the builders seems to orient these monuments for reasons of astronomy.

Furthermore we can deduce that all the tombs are SR according to Michael Hoskin classification.

We can also pointed out that the Lurcu dolmen is faced the rising sun around midwinter sunrise while the orca dolmen is facing the rising of the sun around the midsummer sunrise.

Conclusion

We presented how the introduction of concepts of fields and levels of abstraction allowed the resolution of problems highlighted within the framework of an interdisciplinary research project led to the University of Corsica between anthropologists, archaeologists and data processing specialists. The definition of the concepts of levels of abstraction of space data as well as the concepts of fields allowed an original structuring of space data. Moreover we showed how starting from these concepts we can offer a generic software infrastructure allowing:

-To manage several fields and levels of abstraction of space data, -To define or use transfer functions between levels, -To carry out astronomical analyses between various space data.

The data-processing realization of the various concepts presented is in the course of validation. The software is developed in Visual BASIC what makes it possible on the one hand to implement the various concepts by using a directed design objects and on the other hand to facilitate the integration as of the these concepts in a GIS (Arcview). The validation of the software is carried out within the framework of the interdisciplinary project.

The goal of the project is thus to offer a convivial software environment allowing the development and the use of a GIS integrating the anthropological, archaeological and astronomical data.

. Bibliography

Figure 1 :Figure 2

 12 Figure 1 : Vue 3D des Agriate, Corse du Nord.

Figure 3 :

 3 Figure 3 : Decomposition site en 3 Under (sub-sites (Représentation R2)On level 3, by changing the field (transition from the field «Archaeology» to the field «Astronomy », the user can have access to the functions of tracings and calculation of astronomical values related to the entities of levels 3. In section 5 we give the methodology for computation of these astronomical values.

Figure 4 :

 4 Figure 4: Detailed description of the 3 sites (Representation R3)

  described by Michael Hoskin [4,5] and concerning the south Corsican dolmens. The orientation customs observed by builders of communal tombs in Corsica have been presented in detail in [3]. Eight dolmens of southern Corsica have been measured by Michael Hoskin [3,4,5]. He showed that these dolmens faced easterly or southerly except one facing west. Furthermore he gave the following classification when dealing with astronomical orientations of funerary tombs in the Mediterranean basin :

[

  BED 02] Bédard Y& all,. La méta-structure vuel et la gestion des représentation multiple, Généralisation et représentation multiple, p 149-162, édition hermes 2002.

Table 1 : Orientations of dolmens in Nebbiu zone

 1

	Az.	Alt.	Lat.	Dec.	Tomb
	°	°	°	°
	128	2	42.6	-25 1/2	Dolmen Monte Revincu
	110	4	42.6	-12	Casa di u Lurcu -entrance (Lurcu dolmen)
	130	4	42.6	-25 1/2	Casa di u Lurcu -passage
	75	21/2	42.6	12 1/2	Casa di l'Orca entrance (Orca dolmen)
	60	6°	42.6	25 ½	Casa di L'Orca-Passage

Table 2 : Orientation of early non-dolmenic tombs

 2

	Az.	Alt.	Lat.	Dec.	Tomb
	°	°	°	°
	87	3	42.6	5	Cist near u Lurcu
	95	4	42.6	-1	Cist near l'Orca -Tozzola 1
	108	4	42.6	-10 1/2	Cist near l'Orca -Tozzola 2
	68	2	42.6	17	Tomba di u Lurcu -Pivanosa


Jérémy Dehors

Ferdousse Laggoun

Bruno Gügi

Alain A Mareck

Patrice Lerouge

Arnaud Lehner

Jean-Claude Mollet

Deciphering the links between ROS, Ca 2+ and cell wall remodeling during Arabidopsis thaliana pollen tube growth

Introduction

During sexual reproduction, the male gametophyte carrying the two sperm cells must travel long distancies in the female tissue (Figure 1, 2) to perform the fertilization allowing the production of numerous and healthy seeds. Pollen tubes are fast growing tippolarized cells (Figure 3). To sustain this fast growth, the pol-len tube cell wall must be sufficiently plastic at the tip to promote growth, and rigid at the shank to resist internal turgor pressure. The cell is therefore able to adapt its structure by modifying the cell wall mechanical properties. To this purpose, a rigid cell wall composed of two layers is found in the shank with diWerents cell wall polymers (Figure 3).

Inner layer Callose (mostly) Cellulose

Outer layer Cellulose Hemicellulose s Pectins At the tip, only one layer is found with a composition similar to the outer layer of the shank [START_REF] Dardelle | Biochemical and Immunocytological Characterizations of Arabidopsis Pollen Tube Cell Wall[END_REF]. During pol-len tube growth, massive Golgiderived vesicles containing cell wall polymerssuch as pectins and hemicellulose fuse at the tip to sustain growth. This pro-cess is fine-tuned by reactive oxygen species (ROS)andCa 2+ (Figure 4). Several studies have shown that a perturbation of Ca 2+ pulses at the apex leads to a growth arrest (Pierson et al. 1996). Moreover, inhibition of ROS production decreases the pollen tube length and increase pollen tube burst.

Objectives :

Understand the role of ROS and Ca 2+ during polarized growth Characterize the cell wall modifications triggered by ROS and Ca 2+ oscillation Pharmacological study Immunolabelling of cell wall epitopes

Cell wall

Pectins are secreted at the tip with a high degree of methylesterification and are demethylesterified by Pectin Methyl Esterases (Figure 8A)in the subapical region.

Xyloglucan (the major hemicellulose) is synthesized in the golgi apparatus and made of a β-glucan backbone substituted by xylose, xylose-galactose, or xylose-galactose-fucose (Figure 8B)

Results

Inhibition of ROS production leads to adecrease of the degree of methlesterification (DM) at the tip (Figure 9B)

LaCl leads to a degradation of the wall all along the tube, Fragments of pectin and xyloglucans are detectable in the culture medium (Figure 9D,F)

Figure 1 :

 1 Figure 1 :flower of Arabidopsis thaliana (upper panel) and isolated pis-til covered up of pollen grain (lower panel, Scanning Electron Microscopy). PG : Pollen grain,S: Style,St : Stamens

Figure 2 :

 2 Figure 2 :Pollen tubes of Arabidop-sis thaliana growing in female tissues, from the stigma to the ovules, over distances reaching 100 times the initial pollen size. Aniline blue staining reveals callose in the pollen tube cell wall. PG : Pollen grain, S : Style, TT : Transmitting tract, Ov : Ovary, PT : Pollen tube.

Figure 3 :

 3 Figure 3 :Pollen tube morphology, with a single cell wall layer in the apicale zone (blue) and a bilayer wall on the shank (red) providing a flexibility that ensure apical growth while keeping the cylinder shape of the tube. G : Golgi apparatus, CW : Cell Wall, 1: Outer layer, 2 : Inner layer

Figure 4 :

 4 Figure 4 :Calcium is highly concentrated at the apex and oscillates in time to permit polarized growth (Cárdenas et al. 2008).

Figure 5 :

 5 Figure 5 :Phenotype of pollen tubes after 6 hours of culture. A) Mock in liquid culture medium, B) DPI-supplemented medium (25µM), C) Lanthanum chloride-supplemented medium (50µM ). Arrows indicate burst of pollentubes

Figure 8 :

 8 Figure 8 :Structure of two of the mains cell wall components, the pectin homogalacturonan (A) (from Micheli (2001)), and xyloglucan, the major cell wall hemicellulose (B) (adapted from Del Bem & Vincentz (2010)).

Figure 9 :

 9 Figure 9 :Immuno-detection of cell wall epitops. (A,B) LM20, (C,D) LM19, (E,F) LM25, under control conditions (A,C,E) DPI supplementation (B) or LaCl (D,F).

Table 1 :

 1 List of the diWerent chemicals used and their eWects.

	Methylviologen	ROS inductor
	DPI	NADPHox (ROS producing) Inhibitor
	Nitroarginine	NOS (NO producing) inhibitor
	Sodium benzoate	ROSscavenger
	Lanthanum chloride Calcium channels blocker
	EGTA	Calcium chelator
	Nitroprusside sodium NO inductor
	cPTIO	NO inhibitor


Laggoun Ferdousse

Dardelle Flavien

Driouich Azeddine

Lerouge Patrice

Lehner Arnaud

Mollet Jean-Claude

Arabidopsis pollen tube growth and adhesion: Dissecting the pectin structure using an enzymatic approach

VI. Conclusions and perspectives:

 Pectin-enriched fractions allow Arabidopsis thaliana pollen tube adhesion on an in vitro system.  RG-I backbone and arabinan side chains do not promote pollen tube adhesion. Are galactan side chains of RG-I involved ?  Long chains of HG are needed for adhesion. What is the minimum degree of polymerization of the HG to ensure adhesion?  Pectin from citrus with high DM (85%) is able to promote adhesion. Is the degree of methylesterification of HG important? EdNBISE

1. Deposition of the matrix (70 µg). 2. Water evaporation. 3. Deposition of pollen grains in liquid germination medium. 4. Incubation at 22°C in the dark for 6h. Count the number of pollen tubes in contact with the matrix. 5. Washing step : Flip the plate, rinse 2 times with water, and count the number of remaining adhered pollen tubes.

I. Introduction Pollen grains

Pollen tubes

Transmitting tissue

Ovules

Guidance and adhesion are essential mechanisms for sexual reproduction in flowering plants. The process starts when the pollen grain lands on the stigma, rehydrates and forms a pollen tube that grows through the transmission tact tissue and delivers the two gamete cells to the ovule. The female transmitting tract tissue plays a key role for the pollen tube as it serves as an adhesion matrix ensuring the physical support needed for its progress to the ovules.

As the pectin-enriched matrix was the most efficient in promoting adhesion, we further investigated, using an enzymatic approach, what could be the minimal structure required for in vitro pollen tube adhesion.

Pectins are complex polymers composed of three major domains: homogalacturonan (HG), rhamnogalacturonan-I (RG-I) and rhamnogalacturonan-II (RG-II). The main sugars are galacturonic acid (GalA)(HG and RG-I) that can be methyl and acetyl esterified and rhamnose (Rha), galactose (Gal) and arabinose (Ara) found also in RG-I.

II. Aim of this work

To determine the minimal pectin structure required for Arabidopsis thaliana pollen tube adhesion in vitro.

To date, the involvement of the different components of the cell wall and their relative importance during adhesion is not known. In order to study the role of cell wall components in adhesion, we prepared different matrices, enriched in different classes of cell wall polymers and set up a robust and efficient in vitro adhesion test.

No pollen tube adhesion

Figure 2 :

 2 Figure 1: (A) Effect of pectin and hemicellulose-enriched fractions on pollen tube adhesion. (B) Monosaccharide composition by gas chromatography of the fractions. HG and RG-I backbone levels are indicated. * Pectin from lemon, 85 % degree of methylesterification (DM) (Sigma-Aldrich ® ).

HGFigure 5 :

 5 Figure 5: (A), Effect of an endoarabinanase treatment of the pectinenriched fraction on the adhesion. (B), Dot-blot with the LM6 monoclonal antibody which recognizes epitopes associated with arabinan side chains of RG-I.

Figure 3 :

 3 Figure 3: An endo-polygalacturonase treatment on the pectinenriched fraction and on pectin from lemon (DM = 85%). Pictures show pollen tubes remaining on the matrix after the washing step. scale bar = 200 µm.

Figure 4 :Figure 6 :

 46 Figure 4: Size Exclusion Chromatography (SEC) performed on Sephadex-75G (fractionation range 3 x 10 3 -8 x 10 4 Da) of untreated and treated pectin enriched-fraction and pectin from lemon with endo-polygalacturonase.

Table 2 :

 2 Composition of pectin-enriched fractions from leaves and arabidopsis seed mucilage (extracted with cold water).


El-Hadi Khoumeri
email: khoumeri@univ-corse.fr

Jean-François Santucci
email: santucci@univ-corse.fr

Dominique Federici
email: federici@univ-corse.fr

MULTI LEVEL REPRESENTATION OF SPATIAL DATA ; APPLICATION IN ARCHAEOLOGY AND ANTHROPOLOGY

This paper deals with concepts allowing to integrate and manage different levels of abstraction of spatial data within a GIS. We point out how we resolved the problems set up by the management of multi-view and multi-level spatial data. Finally we detail how the previous resolution approach has been applied efficiently in the framework of a common project at the University of Corsica involving archeologists and anthropologists around an Archeoastronomy project.

Introduction

Starting from a joint project undertaken at the University of Corsica between computer sciences researchers, anthropologists and astronomers we deal in this article with the problem of the definition of the concepts of abstraction levels and views of spatial data for analyzing archeological data. This interdisciplinary project begins with a first research work concerning in particular :

̇ The GPS localization of Neolithic sites and toponyms in the Corsica Island. ̇ GIS representation of the previous data through spatial entities ̇ Analysis of the previous spatial entities described at various abstraction levels.

This first work enabled us to highlight a set of problems when dealing with data coming from the following domains: archaeology, anthropology and astronomy. The solution that we propose for solving the previous problems rests on a definition of abstraction levels for spatial data, as well as the definition of automatic transfer functions between abstraction levels. The implementation of the solution has been carried out using an oriented object design. We present in detail in this article how the definition of the concepts of levels of abstraction and of transfer functions allows the resolution of problems previously highlighted. Moreover we point out how starting from these concepts we can offer a generic software infrastructure allowing in particular:

̇ To manage several levels of abstraction, ̇ To define or use transfer functions between levels, ̇ To carry out geometrical or astronomical analysis between various spatial archeological data.

The generic software infrastructure is developed in Visual BASIC because this language facilitates on the one hand the implementation of the various concepts and on the other hand the integration of these concepts in a GIS. The validation of the software is carried out within the framework of the interdisciplinary project : in a last part of the paper we present how using the previous generic software we have been able to analyze how legends, megaliths and astronomy are linked in the Nebbiu Region in the north part of Corsica..

Problems

Context of the study

The study presented in this article belongs to a set of work concerning the use of the GIS in archaeology. In our case the context of the study is the following : by taking a mix of data from natural and cultural inheritance, the general objective is to offer a powerful software tool for archeologists or anthropologists. This tool should be "open" in the way that it has to offer possibilities, which can comply with complex requests. This gives the researcher all freedom to correlate information. As we will see it below the archeoastronomy rests on studies coming from three distinct fields: archaeology, anthropology and astronomy. Indeed, space is for a society of orality the receptacle of all the inscriptions of it's past, its stories and its beliefs. The toponym allows for the restoration of the awareness of gestures, sounds, the resonance of the place, its values and its properties, supplemented and perpetuated with past generations.

The goal is to work at the interface between the preceding fields in order to try out the capacities of the GIS to being used in the context of a research in archeoastronomy. Archeoastronomy [RUG 99] is the science which relates to the discovery and the study of beliefs and the astronomical practices of the ancient societies; it is initially a tool to include/understand the intellectual achievements of the primitive cultures, such as for example, the builders of megalithic alignments. In order to help archeoastronomers from a point of view of software tools, we have to facilitate the following analysis using GIS: (i) simulate the sky of the ancient people and to calculate the suitable ephemeredes, to then be confronted with oral saves (reconstitution sources of celestial phenomena by the simulation of the aspect of the sky at one time and with a given place); (ii) to establish geometrical links between the different sites, (iii) to study the bonds between toponym and interesting sites from a point of view of archeoastronomy. The goal is to be able to help the archeoastronomers to define following information in a GIS :

̇ GPS localizations of menhirs and dolmens ̇ Abstractions of this information (for example a point represents an alignment of menhirs) ̇ It must possible to carry out geometrical and astronomical analysis.

Space data management and multi-representation

The Geographical Information systems (GIS) started actively to be employed in archaeology during second half of the Eighties [ SAU 90 ]. The capacity of the SIG to incorporate many data, highlighting the bonds between space and human society, made it possible to show the interest of the GIS to undertake research in fields such as archaeology The recent efforts in the field of application of the GIS in archaeology made it possible to start relevant studies concerning the precise knowledge of the landscapes around archaeological sites [ GAF 96 ]. It is certain that in the future the GIS will be more and more associated work of the archaeologists and anthropologists and will integrate also concepts resulting from the artificial intelligence, virtual reality and of course multidimensional modeling [ CLA 95, HAR & SER 95 ]. The use of the SIG in archaeology or anthropology will rest in any event on the capacity of the researchers in the field of the GIS to progress in the problems related to the multi-representation.

Research in multi-representation can be classified in two types of approaches : approaches known as directed treatments using the algorithms of generalization [ RUA 99 ] or many approaches known as directed representations which use a base of data where are stored the various levels of detail [ VAN 98 & ALL 00, SPA 00 ], [ BED 02 ]. With the sight of the analyses and syntheses of these two types of approaches, we can affirm that the definition of concepts authorizing a combination of the two approaches would make it possible to answer effectively the problems highlighted into 2.1. Indeed the user is in certain cases in the obligation to seek new representations not yet stored in the base of data. He cannot in this case be satisfied only directed approaches representations. He must thus call upon approaches known as of treatments what implies a use of generalization in order to generate new representations.

3.

Basic concepts: concepts of domains and levels of abstraction

After an analysis of the capacities of the GIS for researches undertaken in archaeology we identified the following problems to be solved from a computer science point of view :

̇ Difficulty of representing information about space at various levels of abstraction ̇ Difficulty of representing information about space, corresponding to various points of view of localization ̇ Difficulty of connecting information about space in a geometrical way ̇ Difficulty to deduce and of represent data resulting from an astronomy point of view on a GIS.

In order to propose a solution for solving the four previous highlighted problems we developed the concept of levels of abstraction and the concept of domain of spatial data.

A spatial zone will therefore have to be able to be visualized according to various points of view (domains) and at different levels of abstraction : several spatial representations could be associated at a spatial zone. In our study we represent a spatial object as being an elementary spatial pertaining to a representation of a given domain and to a given level of abstraction.

The translation of a representation towards representations more (less) detailed requires the definition of transfer functions of information making possible the automatic generation of a new representation more (less) detailed.

For the same domain, the generation of a representation from a level of abstraction N towards a level of abstraction higher N-1 is named aggregation. The opposite generation is named decomposition. The transfer functions describe how aggregation and the decomposition must be carried out. They are defined by the user or by default in the software system that we propose to create, we can quote like example of transfer function the algorithms of generalization [RUA 99] and [BED 02]. We illustrate in figure 1 all of the concepts previously introduced. The illustration of the generic concepts presented is of course restricted within the framework of the figure of the three fields (archaeology, astronomy and anthropology) but can obviously generalized for unspecified numbers of fields and levels of abstraction. We highlighted in figure 1 how a user interested in the three fields: (archaeology, astronomy, anthropology) will be able to define with no problem, the representations of the same space zone according to different fields and on different levels of abstraction. Moreover they will be able to visualize, navigate and of course generate a representation from another, for a given field.

Within the archaeology field we see on figure 1 that the representation R1 (N-1 level, Archeology field) is composed of a space entity of point type A1 (coordinates x and y) and models for the archaeologists an archaeological complex. However in order to be able to study this complex with one level lower of detail (N), the user will be able, by using the decomposition to generate the representation R2 (level N, archaeology field) made up of three space entities of point type (A2, A3, A4). In this concrete example the point A2 represents a site made up of a dolmen and a menhir, the point A3 an alignment of menhirs and the point A4 a funerary site (trunks + menhirs). The dolmen and menhir are represented in the R3 representation by A21 and A22, we also see in R3 the alignment corresponding to A4. Of course the user can if they wish refine the level of detail by generating the representation R3 (level N+1, archaeology field).

The user can of course within the framework of his studies carry out an automatic passage of the R2 representation towards the R1 representation by using aggregation.

The principle of defining of the levels as well as the associated representations is of course similar within the anthropology field. In this case the basic space entities are polygons and represent toponyms associated with pieces of grounds (example T1, T2, T3). We see clearly on figure 1 The case of the astronomy field is a little different and allows us to illustrate the need for geometrical and astronomical studies. Indeed for a given level of abstraction, the user will be able, for example, to automatically calculate the variation of a space entity of point type P2 (attributes x2, y2, z2) starting from an entity of the point type P1 (x1, y1, z1) and angle A (azimuth). We represent on figure 1 how the angle called variation and associated P2 can be calculated from angle A, and the co-ordinates of P1 and P2, it is necessary to note the importance of the altitude (coordinate Z) in this calculation. Of course the visualization of the data and the results will be backed up by the software system that we develop.

Oriented Object Conception.

In this section we present how the problems highlighted in section 2.2 are solved by an object oriented design of the concepts described in section 3. We call Gis-Archeo-Astro the software system resulting from the implementation. We highlight in particular in this section how:

-To allow a user to define as many domains and levels of abstraction necessary within the framework of a given application.

-To allow a user to associate spatial representation data to a domain and a level of abstraction. -To allow the user to define transfer functions of information which describe the passages between levels of abstraction for a given domain (decomposition and aggregation).

-To allow the user to refer to preset transfer functions which are offered by the software system Gis-Archeo-Astro -To allow the user to carry out geometrical studies between the spatial elements of a given representation -To allow the user to carry out astronomical calculations associated with spatial elements with a given representation and to visualize them.

One can distinguish four stages within the framework of the use of the GIS-Archeo-Astro software:

-Stage 1: the user will be able to define the domains and the levels of abstraction which have to be handled in the following stages ; for each domain, the user will have to define the order of classification of the levels.

-Stage 2: the user will have to define the elementary spatial entities which have to belong to the different levels as well as either to define the transfer functions between levels or to refer to preset transfer functions.

-Stage 3: the user will be able to perform geometrical functions of tracing between the spatial entities defined at stage 2 for a domain and a level of abstraction, defined at stage 1.

-Stage 4: the user will be able to perform calculation of archeoastronomic functions and visualization of these results associated with spatial entities defined at stage 2.

Stages 1 and 2 are backed up by the instantiation of the classes characterizing the following concepts: APPLICATION, ABST-LEV, ENTITY, and TRANSFER. We briefly present the attributes and the main methods that were implemented, for each of the four previous classes.

-The class APPLICATION allows a user to initialize for a given application the levels of abstraction, the domains, and the entities necessary to resolve problems within the framework of the application given.

-Class APPLICATION Attributes: Nb-abs-lev, list-ord-abs-lev, Nb-domains, name-domains: Methods def-abs-lev, def-domains Class ABS-LEV describes the levels of abstraction implied in a given application Class ABS-LEV -Attributes: name-lev, sup-lev, inf-lev -Methods: give-name, to give-sup-lev, give-inf-lev, -Class ENTITY describes an elementary spatial element belonging to a representation at a given level of abstraction and at a given domain. We highlight the two attributes decomp and aggreg. The value of the attribute decomp corresponds to the list of the entities describing the entity considered at a lower level of abstraction, while the attribute aggreg corresponds to the entity at an higher level of abstraction. Finally the attribute transfer corresponds to the name of an instance of the class TRANSFER that will describe the transfer function which will be carried out (decomposition or aggregation).

-Class ENTITY Attributes: abstr-lev, domain, coord-x, coord-y, coord-z (altitude), angle-azimuth, angle-height, angle-declination, decomp, agreg, transfer Methods: affich-circle, affich-polygon, affich-line, afich-azimuth, display-height, affich-decl, calculation-decl -The class TRANSFER describes the transfer functions between levels of abstraction. The entities implied by decomposition or aggregation are enumerated in the attributes entity-departure and entity-arrived. The name of the transfer function to be activated to carry out the decomposition or aggregation is indicated in the name-fct-of-trans attribute, this function will be defined by the user or will be referenced to a preset function.

-Class TRANSFER:

Attributes entity-departure, entities-arrived, name-fct-of-trans, Methods: declch-fct-trans Stages 3 and 4 are backed up by the definitions of methods associated with the class ENTITY. These methods correspond to the various preset geometrical functions of tracing (methods AFFICH-CIRCLE, AFFICH-POLYGON, AFFICH-LINE, etc.) as well as astronomic calculations (method CALCUL-DECL). Moreover the foolowing methods of visualization of archeoastronomic data have been also defined : methods AFFICH-AZIMUT, AFFICH-ALTITUDE, AFFICH-HEIGHT, AFFICH-DECL.

Implementation of the concepts in Visual Basic

The concepts presented in part 3 are validating by the realization of a prototype of a software called Gis-Archeo-Astro developed in Visual BASIC. We chose to validate the previous concepts using the language Visual BASIC (VB) for two main reasons : (i) the integration of the concepts in the GIS Arcview is facilitated by the use of VB since the personalization of Arcview rests on the use of VBA (Visual BASIC Application) ; (ii) the use of VB completely meets the requirement in terms of the ergonomic features associated with the development for interfaces dedicated to not-data processing specialists such as archaeologists or anthropologists. We highlight in this part how a user interested by the three fields (archaeology, astronomy, anthropology) will be able to define without problem the representations of the same spatial zone according to 3 different fields at different levels of abstraction. Moreover it will be able to visualize and of course to generate a representation from another for a given field.

In the examples which follows the concepts of multi-windowing, the functions of geometrical tracing and astronomical calculations are not illustrated for preoccupations with a clearness of presentation. However these concepts are completely integrated into the Gis-Archeo-Astro software which we implemented. The validation was carried out starting from a concrete example concerning the archaeological sites of Monte Revincu.

We have to point out that the megalithic Corsican civilization flourished in the first half of the fourth millennium B.C. This early phase has left numerous traces in Corsica that are to be found everywhere in the southern half of the island and in some very few parts in the northern part (Nebbiu region). As regards burials, there seems in megalithic times to have been the same orientation custom all over the island. The site of Monte Revincu is located in the area of Agriate at the North of Corsica. The landscape is contrasted enough here, it is composed of small narrow valleys or broad depressions. Figure 1 highlights the landscape in 3D as well as the 3 funerary sites of Monte Revincu (called Lurcu, Orca and Monte Revincu). Each one as of the 3 sites is him even made up of one or more megalithic tombs. Figure 2 illustrates the different buttons of the user interface corresponding to the concepts presented in section 3. This figure also highlights a representation of the localization of the site Monte Revincu at the highest level of abstraction ; we will call thereafter this first representation R1 (level 1, Domain archaeology). Figures 3 and4 highlight the transition between levels of abstraction. We see on figure 2 that the first representation R1 is made up of a space entity of type node (coordinated X and y) and models an archaeological complex. However in order to be able to study this archeological complex we need a more detailed view of the complex (level 2). For that , the user will be able by using the decomposition to generate the representation R2 given of figure 3 (level 2, archaeology field) made up of three space entities of type node. These three points can be broken up on a lower level (level 3) in order to study the types of structures composing each one of these sites (dolmens or non-dolmenic tombs). Of course the user can if it wishes it to refine the level of detail by generating the representation R3 (level 3, archaeology field) starting from the representation R2 by clicking on the button «Down ». Figure 4 illustrates this decomposition. The user can also carry out an automatic passage of the representation R2 towards the representation R1 by using aggregation (button «Up "). The passage between levels is carried out using transfer functions. These transfer functions are defined by the users . We must moreover note that the sites at the highest level are indicated by a red point, on level 2 by squares red (see figure 3). Finally on the level 3 several types of points are available corresponding to dolmens or non-dolmenic tombs. The dolmens are located by a red symbol pointing out the shape of a dolmen while the non-dolmenic tombs are represented by a blue symbol having the shape of such a tomb.

Conclusion

We presented how the introduction of concepts of fields and levels of abstraction allowed the resolution of problems highlighted within the framework of an interdisciplinary research project led to the University of Corsica between anthropologists, archaeologists and data processing specialists. The definition of the concepts of levels of abstraction of space data as well as the concepts of fields allowed an original structuring of space data. Moreover we showed how starting from these concepts we can offer a generic software infrastructure allowing: -To manage several fields and levels of abstraction of space data, -To define or use transfer functions between levels, -To carry out astronomical analyses between various space data. The data-processing realization of the various concepts presented is in the course of validation. The software is developed in Visual BASIC what makes it possible on the one hand to implement the various concepts by using a directed design objects and on the other hand to facilitate the integration as of the these concepts in a GIS (Arcview). The validation of the software is carried out within the framework of the interdisciplinary project.

The goal of the project is thus to offer a convivial software environment allowing the development and the use of a GIS integrating the anthropological, archaeological and astronomical data.

  [ MAR 90 ] or anthropology [ ALD 96 ]. According to [ ALD 96 ] the use of the GIS in anthropology is particularly effective in the 5 following cases: ̇ The management of the regional data [ MC G 96 ], ̇ The management of the satellite data [ LOK96, NEY &GRE 99 ], ̇ Regional environmental analysis, ̇ Simulation [ V WES & KOH 96 ] and ̇ The modeling of the sites [ ALD 96 ]. Concerning more particularly archaeology, we can highlight the following uses: ̇ Definition of models for the localization of the sites, ̇ Analyses of archeological sites by the GIS and ̇ Studies related to the archaeology of landscape [ SAU 90 ].

Figure 1 .

 1 Figure 1. Representation of the various levels of abstraction for the 3 fields.

Figure 2 :

 2 Figure 2 : Sight 3d of Agriate, Corsica of North

Figure 3 :

 3 Figure 3 : Localization of Monte Revincu (Representation R1)

Figure 4 :

 4 Figure 4 : Decomposition site on 3 sub-sites (Representation R2)

Figure 5 :

 5 Figure 5: Detailed description of the 3 sites (Representation R3)


El Hadi Khoumeri
email: khoumeri@univ-corse.fr

Ghjasippina Thury-Bouvet

Jean-François Santucci
email: santucci@univ-corse.fr

GIS for archaeoastronomy studies

We present an original approach for performing the study of astronomical events around Neolithic tombs. This approach involves three main steps : (i) the definition of a methodology for generating a 360° view of an horizon using a GIS ; (ii) the integration of the previous view into a commercial software dedicated to astronomy ; (iii) the study of astronomical events linked to the view. We give in this paper a detailed description of software implementation. We point out how the proposed approach has been defined for obtaining an evolutive and efficient tool. Finally, this paper deals with experiments conducted on megaliths belonging to the Monte Revincu zone situated in northern Corsica in order to validate the proposed approach. The effectiveness of the software approach is clearly demonstrated through the obtained results.

I. INTRODUCTION

The field of archaeoastronomy studies the astronomical understanding of ancient cultures and how this understanding influenced their lives. It incorporates the fields of astronomy, archaeology, engineering (for surveying), and anthropology. It focuses on the role that astronomical phenomena have played in human societies, ranging from the applied (such as the basis for calendrics and orientations) to the ceremonial (the significance given the "ritual landscape" of the sky). Archeoastronomy is thus trying to answer the following questions :

• when our earliest ancestors looked up at the sky, what did they see? • how did they interpret what they saw?

• Which astronomical events were most significant and why? • Did astronomical principles govern the construction of their cities, buildings, and temples? The goal of the paper is to propose a software approach which will help any researcher in the field of archaeoastronomy to analyse the links between landscape and celestial events. This approach leans on three main steps : the definition of a methodology for generating a 360° view of an horizon using a GIS ; the integration of the previous view into a commercial software dedicated to astronomy ;

the study of astronomical events linked to the view. We give in this paper a detailed description of software implementation.

We will point out how the proposed approach has been defined for obtaining an evolutive and efficient tool.

Furthermore we will also detail how this approach has been used successfully in the framework of excavation conducted by the DRAC in the area of Monte Revincu in northern Corsica. In this paper we are interested in the megaliths of the Nebbiu Region [12,13,9] and specially those situated around the Monte Revincu. One of our task here is to analyse according to astronomical considerations the orientations that the builders selected for the megaliths which can be found near the Monte Revincu.

The rest of the paper is organised as follows : (i) the field of archaeoastronomy, which is the study of the role of astronomy in early human cultures, will be then presented in detail before a brief overview of our software approach; (ii) the third part will deal with the generation of a 360° view using a GIS ; (iv) in the fourth part we will present how to integrate the previous view into a commercial software dedicated to astronomy ; (v) the last part will describe the results obtained when analysing the astronomical orientations of the megaliths of Monte Revincu.

Finally the conclusions and perspectives will be briefly evocated.

II. ARCHAEOASTRONOMY SOFTWARE APPROACH

A. Why a software approach for archaeoastronomy studies One of the most famous monuments involved in archeaostronomy studies is Stonehenge, England, used between 3000-1800BC. It is a set of huge stones. Figure 1 gives in (a) a view of the site while figure 1 (b) shows us a reconstruction of the monument The main axis of the monument is aligned so that when the sun rises on the summer solstice, it can be seen rising over the distant "heel stone". Other stones are aligned to mark the risings and settings of the sun and moon on other key days. Of course megaliths erected all over Europe are being studied by European archaeoastronomers since the beginning of the seventies. We present in Figure 2 a famous site of Brittany : la Table des Marchands. Figure 2 (a) shows the tumulus with his entrance while figure 2 (b) presents a view of the entrance from the backstone pointed out in figure 2 (c). Two kinds of important sites are the Navetas an dthe Taulas from Menorca presented in Figure 3. Figure 3a gives a nice illustration of a naveta from Menorca within an example from the west part : the Naveta called Es Tudon, while figure 3 (b) and (c) presents two examples of Taulas : Figure 3b shows the Taula called Vela Wells from the south west of the island while figure 3c shows the Taula called Sa Torreta from the northeast part of the island . In both cases as for the other 18 Taulas of Menorca the orientation of these sanctuaries corresponds to the rising and setting of a set of stars forming the Southern Cross at the time of the building of the taulas (between 1400BC and 800BC). Other monuments under study are being found in America. In north America one of the famous example is the Big Horn Medicine Wheel (Wyoming, used around 1500-1740AD). It is a smaller wheel-shaped arrangement of stones in which certain piles of stones align with the rising and setting of the sun at the solstices, and with the rising points of several of the brightest stars. The Plains Indians build many Medicine Wheels across the western USA and Canada. In central and south America the studied monuments belong to the Maya or Azteque civilizations. For example one of the famous monument is the Mayan building now called El Caracol in the city of Chichen Itza (Mexico, built around 1000AD). It had a small room in the upper floor with oddly arranged, slitlike windows that appear to be aligned with sunset on the equinoxes, and with the the setting points of Venus and the bright star Achernar. The Maya had a written hieroglyphic language which has been decoded, and the writings confirm that the Mayan religion was keenly interested in astronomy, particularly the Sun and Venus. There are many archeoastronomical sites around the world, left from many cultures. Several key points are worth remembering :

(1) Most have ties to astronomy through the alignment of principal architectural features (significant stones, windows, doors, streets, etc.) with the rise and/or setting points on the horizon of the sun and/or moon at the solstices and equinoxes, or with bright stars or planets.

(2) At some sites, the astronomical links are more clearly intentional than at others, where evidence and interpretation is a matter of debate --debates that may never be solved because there is little or no written or oral record left by the builders to indicate their true intentions.

(3) The prevalence of these sites indicates that astronomy was an important part of many cultures, either through religion, divination or timing the seasons.

B. Overview of the approach

In order to analyze and study the links between megalithic monuments and the sky at the various times these monuments has been erected (between 5000BC and 800BC) we propose a software approach that will allow to reconstitute the sky at megalithic times within landscapes surrounding a given site. In order to achieve this goal we propose to integrate both a GIS software and an astronomy software. In this paper we deal with MapInfo software [cc] and Starry Night Pro [bb] as astronomy software.

III. GENERATION OF 360° PANORAMIC VIEW USING A GIS

A. 3D Representations using MapInfo.

In order to be able to integrate realistic views of horizon in the Starry night pro software we need to generate a 360° panoramic view from a given point on the earth. This 360° view can be generated by composing a set of views using tools like MapInfo, ER Mapper or Vertical Mapper.

In Vertical Mapper for making 3D map, points are necessary with x,y,z coordinates. This program allows user to see the different perspective views of the terrain and zooming options. Also it allows user to scaling the map along the z axis.

It is part of natural human behavior to observe the (threedimensional) environment through an all-around view over the partial or total horizon. The field of view of the single human eye is limited at 176°. Only by rotating the whole body a complete 360° panorama can be achieved. This methodology is used to compose the 360° view . By moving and rotating around the place you select on the GIS, you will be able to generate a set of pictures that after reconstruction will correspond to the desired 360° view. In 3D Perspective view of the Er Mapper software you manipulate the image as though it is an object in space. Thus, you move the image up and down while you remain in the same place. The functions for moving the image are the following :

Rotate round Y axis Left mouse button-drag left or right Rotate round X axis Left mouse button-drag up or down Rotate round Z axis Left mouse button and plus the right mouse button (hold both down)-drag up or down Zoom in (out) Right mouse button-drag down (up) screen Move Right mouse button plus the left mouse button (hold both down)-drag Vertical Mapper and Er Mapper thus supports the generation of true 3D perspective views. This gives users the ability to compose a MapInfo Map window of any vector, raster or textual entity that coincides with the spatial extents of the grid file and then drape the window onto a 3D representation of the grid surface. The end of the GIS software utilisation is the saving of the set of pictures corresponding to the 3D perspective views needed to compose a 360° panoramic view as described in the following section.

B. Instructions to generate a 3D view from a site

In order to generate a 3D view from a given point using MapInfo software we need to perform the following instructions :

• Click on …..

• ….. • …… • ….;.

IV. INTEGRATION OF AN REALISTIC HORIZON IN A COMMERCIAL ASTRONOMY SOFTWARE

The integration of the previously generated 360° view leans on the writing of two components : (i) an 360° image component which has to be a photoshop [bb] file and (ii) a text component which is an accompanying text file of the previous one.

A. Composing a 360° view

We present how to compose a 360° panoramic view from a set of images obtained using a GIS as described above. The following tips for image processing make use of Photoshop, although other image editing programs can be used.

Step 1. Your raw images will look something like the ones below. The first step is to stitch them together to form a continuous panorama image whose ends match exactly. This is an important step and special care must be taken, otherwise seams will be visible in your final image.

Step 2. The image below shows a stitched 360º panoramic image. This is the most challenging step in creating your own custom landscapes for use in Starry Night.

Step 3. After the image is stitched, use the eraser tool -or a skillful hand with the magic wand and delete key -and remove the sky from your image. The sky is not required because Starry Night will simulate it.

Step 4. The next important step is to add an Alpha channel. Select your 'solid' horizon and add an alpha channel. The black represents 'no transparency' (so that your foreground is opaque) and the white represents '100% transparency' (so that your horizon's sky is transparent and Starry Night can fill it in for you.) Although optional, the Alpha channel allows you to only see the horizon in your final image.

Step 5. When you save the image, save it in "PSD" format.

B. Inserting realistic horizon in Starry Night

In order to be able to perform the link between the image file and the you have to write a set of lines with the general format:

<SN_VALUE name="XXXXX" value="XXXXX">. These lines allow you to change a number of properties for your photorealistic landscape. The most important lines are mentioned below :

-<SN_VALUE name="PanoName" value="YourHor"> You have ti indicate in the value slot name that describes your image. For example value="YoutHor". The name you choose will appear in the drop box in the Horizon Options window under Starry Night Pro.

-<SN_VALUE name="ImageFileName" value="YourHor.psd">

The name of the image you made and placed in the Horizon Panoramas folder. For example if you named your image YourHorrizon.psd", set the value slot to value="MyHorizon.psd". Both the image and text file must be located in the Horizon Panoramas folder.

-<SN_VALUE name="UseImageAlpha" value="Yes"> Set this value as yes if you added an Alpha channel.

The last operation to do is to both put the image and text files in the Horizon Panoramas folder of the Starry Night Pro Software.

V. VALIDATION OF THE APPROACH

In order to validate our approach we choose the area of Monte Revincu in the north of Corsica. The megalithic tombs both dolmens and cists which can be found in this area are associated with a famous oral legend of Corsica : "the legend of the Lurcu".

A. Archaeological and anthropological context

This story is belonging to the North Corsica oral culture. It is a legend from the Nebbiu country and involves people from Santu Petru di Tenda village. The place of the legend is around a set of megaliths, which can be found near the Monte Revincu hill. The story as told by the people from Santu Petru di Tenda is described above. Near the place named Casta was living the Lurcu, a Sheppard, giant, Cyclops, with long hairs. He was living there alone with his mother. We have pointed out on the places where they were living as it is said in the legend coming from centuries and centuries by oral transmission. You can see in the picture that the two giants were living from Saleccia to Monte Rivincu and E purette. They were also going until I Teti and Capu Castincu (where there is a set of Menhirs). This giant was living in a house called u casarone. It is a dolmen whose picture is given in From the dolmen he was able to see Monte Ghjenuva hill (a sacred hill of the area). Another dolmen where was living his mother can be found 500m around the previous one. XX is a picture of this smaller one dolmen. The two dolmens are separated by a plateau named "Cima di Suarella" where a set of megaliths rectangular or circular structures can be found. In Fig. 1 we present the northwest view from the plateau looking in direction of the Casa di u Lurcu. You can see on this figure the Monte Ghjenuva on the back. The giant was very clever. It is said that he knew everything that could be learned at the time. Furthermore he was very powerful so that the people from Santu Petru di Tenda village living near the place called Casta decided to kill him. But he was difficult to catch so that they had to draw the giant into a trap. There is a place near Bocca Pivanosa where the Lurcu was used to come to drink the water of a spring. At night they put a pair of shoes full of pitch in order to capture him. The next morning the Lurcu came to drink and tried the shoes. The people from the village took him easily because of the shoes he was not able to run away. They were going to kill him near the place where there was the water, when the Lurcu told them a secret in order not to be killed: how to do a special cheese (called Brocciu) with sheep milk. After telling them this secret, he was going to tell another secret: what to do with the rest of the milk when the Brocciu has been done. But the mother from the plateau shouted in Corsican language: "Ùn palisà, chì tantu sì mortu" that means "Don't tell them anything because in any case they are going to kill you". They killed both the Lurcu and his mother. They buried the Lurcu near Bocca Pivanosa and the mother near Bocca Murellu. People can find two stone chests.

B. First results obtained using the presented software approach

We spent several days to perform a careful GPS survey of the places of the story. Fig. 2 gives the 3D representation we obtained using the MAPINOF GIS software. By following the instructions described in section 3.A we have been able to generate a file containing a 360°panoramic view of the surrounding of the Orca dolmen. Then after a conversion using the Photoshop software we have been able to generate .psd file as described in 3.C. We then have been able to write an accompanying textfile as presented in 3.C

The result is presented in figure ww. We have been able to insert a realistic horizon in the Starry Night Pro software.

Fig

  Fig. 1. Stonehenge : (a) the monument (b) reconstruction

Fig. 1 .

 1 Fig. 1. Northeastview from "Cima Suarella"

Fig. 2 .

 2 Fig.2. 3D representation of the legend using a GIS SoftwareThen we use the MAPINFO tools in order to generate a 360° panoramic view around the Orca dolmen.By following the instructions described in section 3.A we have been able to generate a file containing a 360°panoramic view of the surrounding of the Orca dolmen. Then after a conversion using the Photoshop software we have been able to generate .psd file as described in 3.C. We then have been able to write an accompanying textfile as presented in 3.CThe result is presented in figure ww. We have been able to insert a realistic horizon in the Starry Night Pro software.

Fig.3. Realistic view of Moon rising above Monte Revincu 3000BC using Starry NightThe picture presents the simulation of the sky the 8 of December 3000 BC at 6:15 pm. You can see own to the

software the rising of the moon near the Monte Revincu as people could have seen it near the Orca Dolmen at this time. We have used this software approach to analyze astronomical event which happened in the are of Monte Revincu between 4200BC and 3000BC. We choose this two dates because the first one corresponds to the earliest datation of the cists in Monte Revincu while 3000BC corresponds to the datation of the dolmens. Of course we have been able to verify the orientations pointed out in previous papers and corresponding to : winter solstice, summer solstice, lunar major standstill. Furthermore astronomical events corresponding to potential target for the builders of the megaliths are been studied : minor lunar standstills and helical rising of Venus. Finally we have to point out that we discover using our software approach that the Halley comet was present above Monte Revincu in July 4200BC. Is it a reason for building the firsts Neolithic tombs under the shape of small cists? Of course the only way to scientifically verify such an hypothesis is to find a great numbers of megalithcs tombs associated with the Halley comet. Furthermore the possibility to simulate the sky and the astronomical events in the realistic landscape near megalithic sites allows to perform an anthropological study of the understanding of the sky at the time when the sites have been built.

VI. CONCLUSION

In this paper we describe a software approach allowing to integrate 360° panoramic view of an area within an astronomical software like Starry Night. We have validated this approach by performing simulation of the sky in a realistic horizon of the landscape around the megaliths of Monte Revincu.

VII. REFERENCES

[l] J.S.