Lionel Clément
email: lionel.clement@inria.fr

Benoît Sagot
email: benoit.sagot@inria.fr

Bernard Lang
email: bernard.lang@inria.fr

Morphology based automatic acquisition of large-coverage lexica

In this article, we introduce a new technique for constructing wide-coverage morphological lexica from large corpora and morphological knowledge, with an application to French. Basically, it relies on the idea that the existence of a hypothetical lemma can be guessed if several different words found in the corpus are best interpreted as morphological variants of this lemma. We first validated our technique by extracting verbs and adjectives on a general French corpus of 25 million words. Compared with other lexical resources available for French, our results are very satisfying, since we cover many words, often derived words, that are not always present in other lexica. Application of our algorithm to the acquisition of domain-specific adjectives on a botanic corpus gave also very good results, thus demonstrating its usability to extract domain-specific lexica. Moreover, it is generalizable to any language with a substantial morphology. Part of the resulting lexicon (currently verbal forms) is already freely available on http://www.lefff.net/.

Introduction

Language processing tasks such as wide-coverage parsers for natural language are often limited because of the lack of lexical resources. Corpus processing for lexical acquisition is now widely used. But lexical acquisition is mostly targeted towards advanced information such as terminology [START_REF] Daille | Morphological rule induction for terminology acquisition[END_REF], collocations [START_REF] Dunning | Accurate methods for the statistics of surprise and coincidence[END_REF], or sub-categorization properties [START_REF] Briscoe | Automatic extraction of subcategorization from corpora[END_REF], and assume the availability of basic information such as parts-of-speech and inflectional categories, usually referred to as lexica. However, the acquisition of this basic information gets relatively little discussion in the literature, partly because this problem is both minimal and largely solved for English, and although it is a prerequisite to the acquisition of more advanced information. For languages like French, large-coverage lexical resources are not numerous, and are not always freely available.

Our approach makes it possible to extract from a large raw corpus a list of lemmas with their associated morphological information (part-of-speech, inflectional category, as well as prefix when appropriate). The resulting lexicon can then be compared with other available lexica, usually commercial or with restricted licenses, such as the morphological word lists extractable from ATILF databases [START_REF] Dendien | Le trésor de la langue franc ¸aise informatisé : un exemple d'informatisation d'un dictionnaire de langue de référence[END_REF], MulText [START_REF] Ide | MULTEXT: Multilingual text tools and corpora[END_REF], or ABU (Association des Bibliophiles Universels, ABU). These lexica are mostly built by human lexicographers, and therefore are both costly to develop and subject to mistakes and omissions. The results of our work is complementary to these lexica, since such problems can be partially avoided by the mechanization of the process, although it has other drawbacks, like over-generation. Since our method is based on corpus statistics, it is related to works on terminology acquisition. However, our goal is not to acquire (possibly multi-words) terms, but lexical entries.

General framework

The acquisition of the lexicon of a given corpus can be seen as the extraction of the lemmas of all forms of the corpus among all morphologically acceptable lemmas which have at least one of their form that is attested in the corpus. This extraction is then a matter of separating correct lemmas from incorrect ones among all possible lemmas. To achieve this separation, one need a way to grade possible lemmas according to their plausibility.

At that point, the acquisition process described in this article is based on the following underlying idea. The plausibility of a lemma is correlated with the number of different forms of lemma attested in the corpus, and -to a lesser extent -with the number of occurrences of these forms. This supposes that the language studied has a morphology that is rich enough to associate several forms to each lemma. It is the case for example for romance languages (especially for verbal inflection), but also for richmorphology languages like for example slavic languages or latin.

In French, for example, the richest morphology is that of verbs. A typical verbal inflection contains more than 40 different forms. Thus, if attested forms constitute a significant part of the inflection of a possible verbal lemma, this lemma is most probably correct, and can be acquired.

Algorithm overview

Before reaching the core loop of our algorithm, there are two preliminary steps to go through.

The first preliminary step of our algorithm is to tokenize the corpus. In the following, we shall use the word form as a synonym for token. We call tagged form a form supplemented with morphological information such as gender, number, tense, person, etc. An inflectional category is an operator that computes a set of tagged forms from a single input called canonical form. A lemma is defined as a canonical form associated with an inflectional category. Our aim is to acquire a full-forms lexicon that links tagged forms to their lemma(s). To achieve the tokenization of our corpus, we used Clement's tokenizer splitwords, simply based on regular expressions.

Once tokenized, the corpus is tagged to split up forms according to their part-of-speech. This step is not absolutely necessary to acquire the most frequent lexical units. However, to achieve quasi-exhaustivity, we have to associate to rare forms their part-of-speech. Indeed, the part-of-speech of a lemma (and thus its inflectional category) is almost impossible to discover by morphological analysis alone, if only a very low number of different inflected forms represent it in the corpus. But this doesn't mean that we extract the lexicon on which the tagger relies -if any. Indeed, the tagger we used, namely TreeTagger, has been trained on a 700,000-word tagged corpus and with a lexicon that includes only closed-class words (articles, pronouns, prepositions, conjunctions, etc.), but no open-class word (noun, adjective, verb, adverb). Any other tagger not relying on an open-class lexicon could have been used to perform this tagging task1 .

Our extraction of the lexicon from the corpus can then be seen as the iteration of a three steps loop:

• Construction of possible lemmas,

• Ranking of these lemmas,

• Hand validation of best-ranked not already validated lemmas.

Construction of possible lemmas

This step can be divided in three parts. Firstly, and if we are not in the first execution of the loop, information given by hand during previous steps (in a way described hereafter, see 3.3.) are used to filter the corpus to reject misspelled words and other typos.

The second part is the construction of possible lemmas itself. This strongly relies on the availability of morphological knowledge. We have developed an inflection module for french verbs, adjectives and nouns (adverbs being invariable), based on standard descriptive grammars for French language [START_REF] Bescherelle | La conjugaison -Dictionnaire de douze mille verbes[END_REF][START_REF] Grevisse | Le bon usage, grammaire franc ¸aise[END_REF]. For each not previously filtered word of the corpus, we use this module backwards to compute all possible lemmas having this word as a morphological variant. Our morphological module is precise enough to generate only lemmas that match French morphology. We then filter the result of this process by ruling out the (few) lemmas rejected by hand during previous iterations of the loop (cf. 3.3.).

The third part of this step deals with prefixes. Indeed, decomposing the canonical form of a lemma in a prefix and a derivational basis can be very useful for a lot of tasks, including lexicon acquisition itself: a possible lemma is much more likely to be correct if it can be analyzed as a derivation of a known lemma by the adjunction of a standard prefix (this adjunction has usually to respect specific constraints2 ). Therefore, we try to decompose the canonical form of each generated lemma into one of predefined prefixes (the list depending on the part-of-speech) and the canonical form of an already generated lemma, with the additional constraint that the inflectional category has to be the same for both lemmas. If a prefix is recognized, two separate lemmas are generated, the first with a raw canonical form, and the second one representing explicitly its canonical form as the concatenation of a prefix and a derivational basis.

At the end of this first step, we obtain a list of formlemma pairs, associating several possible lemmas to each form.

Ranking of lemmas

Lexical acquisition techniques must be able to extract not only very common lemmas, but also poorly attested lemmas, without too much over-generation (noise). This is achieved by ranking both lemmas and form-lemma pairs that justify them.

Formally, given a lemma l generating a form f , let P (l) be the probability that l is a proper lemma (i.e. that the lemma l is attested in the corpus by at least one of its forms) and P (f ≺ l) is the probability that this lemma explains a given attested form f in the corpus. Let L f be the set of all lemmas generating the form f , and F att l the set of all attested forms generated by the lemma l. We introduce the number of occurrences of a form f in the corpus occ(f ), and the number of occurrences of a lemma l in the corpus, which is:

occ(l) = f ∈F att l P (f ≺ l).occ(f ).
We also introduce the probability P l (f ) for a form of the lemma l to be the form f (depending on l's inflectional class), and the probability P (f |l) for a given form f to be attested in the corpus if the lemma l is attested. The latter satisfies the following equation:

P (f |l) = 1 - l∈L f 1 -P l (f ) occ(l) .
Given these definitions, our algorithm is based on the sensible assumption that the following equations are satisfied :

P (f ≺ l) = P (l).P (f |l) l ∈L f P (l ).P (f |l ) P (l) = 1 - f ∈F att l (1 -P (f ≺ l)).
The first equation is a Bayes formula, and the second expresses the fact that a lemma l is not attested in the corpus if none of its attested (but ambiguous) forms is recognized as generated by l.

To compute approximatively the probabilities of lemmas, we use these equations in an iterative fix-point computation to solve these equations.

Hand validation

The first iteration of the computation described in the previous paragraph leads to a result which is good but has noise, mostly because of misspelled or mistagged words in the corpus3 . They can have two different consequences:

• one -or a couple of -misspelled or mistagged word can justify a wrong lemma which has these words as only form ("wrong-form-based lemmas"), as for example "démesurer", based on the noun "démesure" and the adjective "démesuré", both mistagged as verbs,

• one -or a couple of -misspelled or mistagged word can influence a true lemma by giving it a wrong inflectional category and/or by changing its spelling ("misguessed lemmas"), as for example "reconstruir", based on several forms of the correct lemma "reconstruire" and on the misspelled word "reconstruir".

Mistakes can also be errors of the acquisition algorithm itself, introducing incorrect lemmas with a probability P (l) = 1 that are based only on correct forms, as for example "rendormer" instead of "rendormir". However, in our experiments, this occurs very rarely (see 4.). Thus, and because any good quality lexicon has to be hand-validated anyway, we then ask a native speaker to validate the n best-ranked lemmas (n being usually 500 in our case). Three judgments can be given to a lemma: it can be set as valid, it can be set as "wrong-form-based" because generated only by wrong forms, or it can be set as "misguessed" because it is wrong although generating some correct attested forms. We must point out the fact that this hand-validation is not very costly, since lemmas are already well ordered, and since the validation task is extremely simple. This cost has nothing to do with the cost of previous methods to develop a lexicon, basically based only on human lexicographers. Furthermore, we facilitate hand-validation by grading lemmas l such as P (l) = 1 by the number occ(l) of occurrences of the lemma l if it has no prefix, and by occ(l) + 10 if it has a prefix4 .

The results of this hand-validation is used to create both above-mentioned filters:

1. newly rejected lemmas, are appended to the list of rejected lemmas, 2. all forms of new wrong-form-based lemmas, and forms only explainable by new misguessed lemmas, are appended to the list of rejected forms.

The whole three-steps loop is then reiterated, until bestranked not-yet-validated lemmas have a probability close to zero.

Preliminary results

On our general corpus, the fix-point algorithm takes a few minutes to converge, thus allowing fast iteration of the whole loop. The necessary manual validation is greatly helped by the quality of the plausibility measures computed. The first application of our method was to acquire the verbal lexicon of a 25 million words general (journalistic) French corpus. After the first iteration of the loop (thus without any filtering), the 100th incorrect lemma had rank 3337, and 7500 lemmas have a probability P (l) ≥ 1, out of which 5250 have an number of occurrences at least equal to 1. It is noticeable that almost all incorrect lemmas come from misspelled or mistagged words (respectively 19% and 76% of the 100 best-ranked incorrect lemmas), and not from bad guesses of the algorithm based on correct forms (5%). The following table gives the number of correct and incorrect lemmas depending on their number of occurrences5 after the first iteration of the loop, given by the comparison with the final acquired lexicon described hereafter. Of course these intermediate results are not supposed to be perfect, and are given only as illustration. Indeed, better results after the first iteration could be easily achieved with stronger constraints on acceptable forms (e.g. a form could be rejected if it occurs only once, or if it is tagged as non-verb more that a given percentage of the time), but it would reduce the number of learnable lemmas. Here, we give priority to lower silence over lower noise, because hand-validation will decrease noise more and more during the iteration process.

After one iteration, lemmas l such as P (l) > 0.97 occ(l) After only a few hours of manual validation and loop iteration, a lexicon of nearly 5000 verbs was achieved 6 , generating approximately 200,000 forms, out of which several hundreds are not in the standard reference [START_REF] Bescherelle | La conjugaison -Dictionnaire de douze mille verbes[END_REF], even though attested in a non-specialized corpus. Around 1500 verbs of [START_REF] Bescherelle | La conjugaison -Dictionnaire de douze mille verbes[END_REF] are not acquired, most likely because they are not attested in the corpus, as suggested by the following check. In order to evaluate our work, we tagged our corpus using a ver-sion of TreeTagger that we trained with an other freely available lexicon (Association des Bibliophiles Universels, ABU) ; only 1.64% of words tagged as verbs are not derivable from our acquired lexicon, which can be compared with the mean error rate of the this tagger, 3.25%. A manual check shows that these 1.64% are indeed almost always mistakes of the tagger. This lexicon of French verbs is the first part of our general French lexicon LeFFF (Lexique des Formes Fléchies du Franc ¸ais -Lexicon of Inflected Forms of French), available at http://www.lefff.net/ under an open-source license published on the web site.

Our preliminary results on adjectives gives us approximatively 10000 lemmas from the general corpus. We then applied our algorithm on a botanic corpus of 3 million words: after the first pass, out of the first 1000 ranked adjectival lemmas, 350 are unknown to the previously built general lexicon, and almost all of them are indeed correct specialized terms.

Conclusion

While preliminary, our results demonstrate the feasibility of mechanized acquisition of wide-coverage lexica from general or specialized corpora, with very limited human labor7 . The resulting wide-coverage French lexicon is made progressively available under a free-software license (at http://www.lefff.net/). Further work could include the improvement of the current algorithm, the acquisition of specialized lexica (as started on botanics), and the acquisition of lexica for other dialects of French or other languages with a rich morphology. In fact, we are in the process of globalizing our approach to be able to take into account derivational morphology, thus validating a lemma not only by its attested forms but also by its derivatives, in order to acquire the lexicon in a global way. Such a method should facilitate even more the fast acquisition of large-coverage lexica. It could even bring interesting linguistic results on derivational morphology, including subcategorization information through derivation links, and basic lexical semantics through linguistic knowledge about derivational morphology.

As explained in the following part, the lexicon learning process is incremental. Therefore, the partial lexicon learned after the n-th iteration of the process could be used to learn anew the tagger, then tag the corpus again in a more accurate way, and use this newly tagged corpus for the n + 1-th iteration. We didn't experiment this process yet because we decided to first improve the acquisition of the lexicon in a more drastic (and complementary) way, by taking into account globally cross-parts-of-speech morphological derivations. This work, currently in progress, will be published

later.2 For example, in French, the verbal prefix "dé-" can correspond to English prefixes "un-": "défaire" means "to undo" and is based on "faire", which means "to do". However, if the deriva-

tional basis begins with a vowel phoneme, this prefix is extended with an extra "s": "obéir" ("to obey") is related to "désobéir" ("to disobey"). By "specific constraints" we mean this kind of phenomena.

Misspelled words are a tough problem, because they are unavoidable in a corpus. Furthermore some spelling mistakes are systematic, thus giving rise to consistent sets of (misspelled) inflected forms, which are best interpreted as a well-attested misspelled

lemma. 4 This incrementation by 10 if is the result of an empirical statistical analysis (depending on the corpus we used), so that the function giving the probability of correctness depending on the number of occurrences is the same both for lemmas with and without prefixes.

For lemmas with prefix, number of occurrences is increased by 10. See previous footnote.

This number is slightly higher than the previously given 4759 (see Table1) because we hand-validated also words with a number of occurrences and/or a probability P (l) lower than 1.

The small amount of human input (filtering of forms and lemmas) can be memorized, thus making the acquisition process reproducible, and opening it to scrutiny, comparison, criticism and improvement.


J Ericson

Marteau

M Martini

G Chanfray

M Ericson

J Marteau

Neutrino interactions with nuclei

Keywords: Neutrino-nucleus interactions, Quasi-elastic scattering, Pion production, Coherent scattering PACS: 25.30.Pt, 13.15.+g, 24.10.Cn

Neutrino interactions with nuclei

INTRODUCTION

Various theoretical approaches [1] have been used to interpret the experimental results on neutrino interactions with matter [2,3,4,5,6,7,8,9] in quasi-elastic processes or coherent and incoherent single pion production.

In our work, we explore these interactions in the energy region around 1 GeV using the formalism of the nuclear response functions treated in the random phase approximation (RPA) and incorporating Delta-resonance excitation as in the work of Marteau [10]. This approach has the merit of describing in a unique frame several final state channels i.e. quasi-elastic, incoherent and coherent one-pion production and two-or several-nucleon knock-out. In the following we present the results obtained for each of them.

Several types of nuclear responses enter the total neutrino-nucleus cross-section: the isovector R τ , the spin-isospin transverse R σ τ(T ) or longitudinal R σ τ(L) . In order to illustrate this point, we give below a simplified expression of the double differential cross-section for the reaction ν l ( νl ) + A -→ l -(l + ) + X which, in particular, ignores the lepton mass contribution and assumes zero ∆ width:

∂ 2 σ ∂ Ω ∂ k ′ = G 2 F cos 2 θ c ( k ′ ) 2 2 π 2 cos 2 θ 2 G 2 E ( q 2 µ q 2 ) 2 R NN τ + G 2 A (M ∆ -M) 2 2 q 2 R N∆ σ τ(L) + G 2 A (M ∆ -M) 2 q 2 R ∆∆ σ τ(L) + G 2 M ω 2 q 2 + G 2 A - q 2 µ q 2 + 2 tan 2 θ 2 R NN σ τ(T ) + 2R N∆ σ τ(T) + R ∆∆ σ τ(T ) ± 2 G A G M k + k ′ M tan 2 θ 2 R NN σ τ(T ) + 2R N∆ σ τ(T) + R ∆∆ σ τ(T )
.

(1)

For the variable definitions and for the complete formulas we refer to [10,[START_REF] Martini | A unified approach for nucleon knock-out, coherent and incoherent pion production in neutrino interactions with nuclei[END_REF]. We stress that in the actual calculations we make use of the full formulas.

The various responses R appearing in Eq.( 1) are related to the imaginary part of the corresponding full polarization propagators through

R(q, ω) = - 1 π ImΠ(q, q, ω). (2)
They are calculated within a RPA ring approximation, starting from "bare" propagators (meaning that the nuclear correlations are switched off) and solving integral equations which have the generic form

Π = Π 0 + Π 0 V Π, (3)
where V denotes the effective interaction between particle-hole excitations. 12 C versus pion kinetic energy for several ν µ energies. Right panel: total cross-section for charged (divided by a factor 2) and neutral current coherent pion production as a function of the ν µ energy.

The bare polarization propagator is density dependent. In a finite system, Π 0 ( q, q ′ , ω) is non-diagonal in momentum space. In order to account for the finite size effects we evaluate it in a semi-classical approximation where it can be cast in the form

Π 0 ( q, q ′ , ω) = d r e -i( q-q ′ )• r Π 0 q + q ′ 2 , r, ω . (4)
In practice we use a local density approximation,

Π 0 q + q ′ 2 , r, ω = Π 0 k F (r) q + q ′ 2 , ω , (5)
where the local Fermi momentum k F (r) is related to the experimental nuclear density through:

k F (r) = (3/2 π 2 ρ(r)) 1/3 . (6)
The bare response is the sum of the following partial components: (1) NN quasi-elastic (as described by the standard Lindhard function); ( 2 The RPA response generically writes

ImΠ = |Π| 2 ImV + |1 + ΠV| 2 ImΠ 0 . (7)
It splits in two terms. The first implies a cut on the pion exchange potential V π . It represents the coherent pion production where the nucleus is left in the ground state. The second, proportional to the bare polarization propagator ImΠ 0 , reflects the type of final state already mentioned in the bare case, modified by collective effects.

RESULTS AND COMPARISON WITH DATA

Coherent pion production

The response naturally associated to the coherent process is the spin-isospin longitudinal one, since it has the same coupling as the pion. We have tested our description of the coherent responses on the elastic π -12 C scattering which is sensitive to collective effects in the longitudinal channel. We have also checked the compatibility of our evaluation of neutrino differential cross-section in the forward direction with the experimental π -12 C elastic scattering cross-section, according to Adler's theorem.

Figure 1 displays our evaluations of the coherent pion production off 12 C as a function of the pion kinetic energy, both for charged and neutral current, for several neutrino incident energies. The resulting total coherent cross-sections are also shown as a function of the neutrino energy.

ν µ + 12 C --> µ -+X E ν = 1 GeV FIGURE 2.
Left panel: differential ν µ -12 C charged current cross-section as a function of transferred energy in the various channels for E ν =1 GeV. Right panel: total ν µ -12 C charged current cross-section in the various channels.

Quasi-elastic and multi-nucleon channels

The quasi-elastic channel corresponds to a single-nucleon knock-out. In contrast to the coherent channel, the quasielastic process is dominated by the transverse response. The quasi-elastic cross-section is displayed in Fig. 2 as function of the energy transfer ω, for a neutrino energy of 1 GeV, both in the bare and in the RPA cases. The RPA effects tend to reduce the cross-section, as expected from the repulsive character of the particle-hole interaction which dominates in the transverse channel. In the same figure we display the sum of the two-and three-nucleon knock-out cross-section, which represents a sizable fraction of the quasi-elastic one. Singling out the genuine quasi-elastic process requires the insurance that no more than one proton is ejected. This issue will appear in connection with the comparison to data. Part of multi-nucleon channels arises from the modification of the Delta width in the medium where other decay channels are possible [START_REF] Oset | [END_REF]. The remaining contribution is taken from [START_REF] Delorme | Proceedings of the 5th french-japanese symposium on nuclear physics[END_REF][START_REF] Shimizu | [END_REF]. In neutrino interactions this last part of the cross-section is important but not very well constrained by phenomenology.

Incoherent pion emission

Turning now to incoherent pion emission, the pion arises from the pionic decay of the Delta leaving the nucleus in a particle-hole excited state. For the nucleus that we consider, the incoherent pion cross-section is much larger than the coherent one. As compared to a free nucleon, the emission probability is already reduced in the bare case by the change in the Delta width. Moreover the RPA effects, which are moderate, also contribute to this reduction. The reduction due to the modification of the Delta width has a counterpart in the presence of the multi-nucleon knock-out component discussed before.

All the previous results are summarized in Fig. 2 which displays the muon-neutrino differential cross-section in the various channels as a function of the energy transfer for the case of 12 C and a neutrino energy of 1 GeV. The total neutrino cross-section is also displayed. The incoherent π channel includes all possible charge states. In our evaluation the incoherent π + channel results to be 5/6 of the total.

Comparison with data

Experimental data concern ratios between different cross-sections. For charged current, the K2K collaboration has established a 90% confidence-level upper bound on the ratio of coherent pion production to the total cross-section, giving a limit of 0.60 10 -2 averaged over the neutrino flux with a mean energy of 1.3 GeV [4]. More recently, the SciBooNE collaboration found for the same quantity 0.67 10 -2 at neutrino energy of 1.1 GeV [8]. We report in the left panel of Fig. 3 our prediction for this quantity. Our curve is just compatible with the experimental limit. FIGURE 3. Left panel: ratio of the ν µ -induced charged current coherent pion production to total cross-section. Central and right panels: ratio of the ν µ -induced charged current one pion production to quasi-elastic cross-section.

Another measured quantity is the ratio of π + production to quasi-elastic cross-section for charged current. The MiniBooNE collaboration has used a CH 2 target. In order to compare with ANL [2] and K2K [7] data, they presented the results applying an isoscalar rescaling correction [9]. The issue of pion loss by final state interaction, which is not incorporated in our description, has also been taken into account by MiniBooNE who corrects data for this effect. We can thus compare our π + over quasi-elastic ratio (solid line in the central panel of Fig. 3) to the final-state-interaction- corrected MiniBooNE results. Our curve is fully compatible with experimental data.

As an additional information, MiniBooNE also gives a ratio more directly related to the measurements, namely the ratio of pion-like events (defined as events with exactly one µ -and one π + escaping the struck nucleus) and quasi- elastic signal (defined as those with one µ -and no pions). In our language the last quantity represents the np -nh (including the quasi-elastic for n = 1) exclusive channel. We have compared this second experimental information with the ratio between our calculated pion production (which however ignores final state interactions) and our total npnh contribution to the total charged current neutrino cross-section (right panel of Fig. 3). The comparison shows an agreement up to E ν ≃ 1.2 GeV. This may be an indication that final state interactions for the pion is not essential here. Our theoretical approach predicts a strong contribution of 2p -2h and 3p -3h channels which seems to be supported by the last comparison.

  ) NN 2p-2h; (3) N∆ and (3 ′ ) ∆N 2p-2h; (4) ∆∆ π N; (5) ∆∆ 2p-2h; (6) ∆∆ 3p-3h.

  Left (central) panel: differential cross-section for charged (neutral) current ν µ -induced coherent pion production off

														0.07
		0.3				CC		0.15				NC 12 C		0.06		σ NC σ CC /2
	dσ/dT π [10 -38 cm 2 /GeV]	0.1 0.15 0.2 0.25						0.05 0.075 0.125 0.1			E ν = 0.5 GeV E ν = 1 GeV E ν = 1.5 GeV	σ [10 -38 cm 2 ]	0.02 0.03 0.05 0.04
		0.05						0.025						0.01
		0	0	0.2	0.4	0.6	0.8	0	0	0.2	0.4	0.6	0.8	0	0	0.2	0.4	0.6	0.8	1	1.2	1.4
					T π [GeV]						T π [GeV]								E ν [GeV]
	FIGURE 1.


Philippe Blache
email: blache@lpl-aix.fr

A general scheme for broad-coverage multimodal annotation

We present in this paper a formal and computational scheme in the perspective of broad-coverage multimodal annotation. We propose in particular to introduce the notion of annotation hypergraphs in which primary and secondary data are represented by means of the same structure.

This paper addresses the question of resources and corpora for natural human-human interaction, in other words broad-coverage annotation of natural data. In this kind of study, most of domains have do be taken into consideration: prosody, pragmatics, syntax, gestures, etc. All these different domains interact in order to build an understandable message. We need then large multimodal annotated corpora of real data, precisely annotated for all domains. Building this kind of resource is a relatively new, but very active research domain, illustrated by the number of workshops (cf. [START_REF] Martin | Proceedings of the Workshop on Multimodal Corpora : From Models of Natural Interaction to Systems and Applications[END_REF]), international initiatives, such as MUMIN [START_REF] Allwood | The MUMIN Multimodal Coding Scheme[END_REF], annotation tools such as NITE NXT [START_REF] Carletta | The NITE Object Model Library for Handling Structured Linguistic Annotation on Multimodal Data Sets[END_REF], Anvil [START_REF] Kipp | Anvil-a generic annotation tool for multimodal dialogue[END_REF], etc.

A characterization of primary data

Different types of primary data constitute the basis of an annotation: speech signal, video input, word strings, images, etc. But other kinds of primary data also can be used, for example in the perspective of semantic annotations such as concepts, references, types, etc. Such data are considered to be atomic in the sense that they are not built on top of lower level data. When looking more closely at these kinds of data, several characteristics can be identified: -Location: primary data is usually localized with respect to a timeline or a position: gestures can be localized into the video signal, phonemes into the speech one, words into the string or objects into a scene or a context. Two different kinds of localisation are used: temporal and spatial. In the first case, a data is situated by means of a time interval whereas spatial data are localised in terms of relative or absolute positions.

-Realization: primary data usually refer to concrete (or physical) objects: phonemes, gestures, referential elements into a scene, etc. However, other kinds of primary data can be abstract such as concepts, ideas, emotions, etc.

-Medium: The W3C recommendation EMMA (Extensible Multi-Modal Annotations) proposes to distinguish different medium: acoustic, tactile and visual. This classification is only relevant for data corresponding to concrete objects.

-Production: the study of information structure shows the necessity to take into account accessibility of the objects: some data are directly accessible from the signal or the discourse, they have an existence or have already been mentioned. In this case, they are said to be "produced". For example, gestures, sounds, physical objects fall in this category. On the other hand, other kinds of data are deduced from the context, typically the abstract ones. They are considered as "accessible".

In the remaining of the paper, we propose the following definition:

Primary data: atomic objects that cannot be decomposed. They represent possible constituent on top of which higher level objects can be built. Primary data does not require any interpretation to be identified, they are of direct access.

This primary data typology is given in figure (1). It shows a repartition between concrete vs. abstract objects. Concrete objects are usually those taken into account in corpus annotation. As a consequence, annotation usually focuses on speech and gestures, which narrows down the set of data to those with a temporal localization. However, other kinds of data cannot be situated in the We need to propose a more general approach of data indexing that has to distinguish on the one hand between temporal and spatial localization and on the other hand between data that can be located and data that cannot.

Graph representation: nodes and edges semantics

One of the most popular linguistic annotation representation is annotation graphs [START_REF] Bird | A formal framework for linguistic annotation[END_REF] in which nodes are positions whereas edges bear linguistic information. This representation is elaborated on the basis of a temporal anchoring, even though it is also possible to represent other kinds of anchoring. Several generic annotation format has been proposed on top of this representation, such as LAF and its extension GrAF (cf. [START_REF] Ide | GrAF: A Graph-based Format for Linguistic Annotations[END_REF]). In these approaches, edges to their turn can be interpreted as nodes in order to build higher level information. One can consider the result as an hypergraph, in which nodes can be subgraphs.

In order to explore farther this direction, we propose a more general interpretation for nodes that are not only positions in the input: nodes are complex objects that can be referred at different levels of the representation, they encode all annotations. In order to obtain an homogeneous representations, the two node types used in hypergraphs (nodes and hypernodes) share the same information structure which relies on the following points: -Index: using an index renders possible to represent any kind of graphs, not only trees. They give to nodes the possibility of encoding any kind of information.

-Domain: prosody, semantics, syntax, gesture, pragmatics, etc. It is important to indicate as precisely as possible this information, eventually by means of sub-domains -Location: annotations generally have a spatial or a temporal situation. This information is optional.

-Features: nodes have to bear specific linguistic indications, describing its properties.

Hypernodes bear, on top of this information, the specification of the subgraph represented by its constituents and their relations. We propose to add another kind of information in the hypernode structure:

• Relations: secondary data are built on top of primary one. They can be represented by means of a set of properties (constituency, linearity, coreference, etc.) implemented as edges plus the basic characteristics of a node. A secondary data is then graph with a label, these two elements composing an hypernode.

The distinction between node and hypernodes makes it possible to give a homogeneous representation of primary and secondary data.

An XML representation of annotation hypergraphs

We propose in this section an XML encoding of the scheme presented above.

Atomic nodes

The first example of the figure (2) illustrates the representation of a phoneme. The node is indexed, making its reference possible in higher level structures. Its label corresponds to the tag that would be indicated in the annotation. Other elements complete the description: the linguistic domain (specified by the attributes type and sub-type), the specification of the medium, the object localization (by means of anchors). In this example, a phoneme being part of the acoustic signal, the anchor is temporal and use an explicit timeline reference.

The same kind of representation can be given for transcription tokens (see node n21 in figure (2)). The value of the node is the orthographic form. It is potentially aligned on the signal, and then represented with a temporal anchoring. Such <node ID="n1" label="u"> <domain type="phonetics" subtype="phoneme" medium="acoustic"/> <anchor type="temporal" start="285" end="312"/> </node> <node ID="n21" label="book"> <domain type="transcription" subtype="token"/> <anchor type="temporal" start="242" end="422"/> </node> <node ID="n24" label="N"> <domain type=" morphosyntax" subtype="word"/> <anchor type="temporal" start="242" end="422"/> <features ms="ncms---"/> </node> <node ID="n3" label="deictic"> <domain type="gestures" subtype="hand"/> <anchor type="temporal" start="200" end="422"/> <features hand="right" deictic type="space" object="ref object"/> </node> <node ID="n4" label="discourse-referent"> <domain type="semantics" subtype="discourse universe" medium="visual"/> <anchoring type="spatial" x="242" y="422" z="312"/> <features isa="book" color="red" /> </node> anchoring makes it possible to align the orthographic transcription with the phonetic one. In the case of written texts, temporal bounds would be replaced by the positions in the texts, which could be interpreted as an implicit temporal anchoring.

The next example presented in node n24 illustrates the representation of part-of-speech nodes. The domain in this case is morphosyntax, its subtype is "word". In this case too, the anchoring is temporal, with same bounds as the corresponding token. In this node, a feature element is added, bearing the morpho-syntactic description.

The atomic node described in node n3 represents another physical object: a deictic gesture. Its domain is gesture and its subtype, as proposed for example in the MUMIN scheme (see [START_REF] Allwood | The MUMIN Multimodal Coding Scheme[END_REF]) is the part of the body. The anchoring is also temporal and we can observe in this example a synchronization of the gesture with the token "book".

The last example (node n4) presents an atomic node describing a physical object present in the scene (a book on a shelf of a library). It belongs to the semantics domain as a discourse referent and is anchored spatially by its spatial coordinates. One can note that anchoring can be absolute (as in the examples presented here) or relative (situating the object with respect to other ones).

Relations

Relations are represented in the same way as nodes. They are of different types, such as constituency, linearity, syntactic dependency, semantic specification, etc. and correspond to a certain domain. The example r1 in figure (3) illustrates a specification relation between a noun (node n21, described above) and its determiner (node n20). Non-oriented binary relations also occur, for example cooccurrency. Relations can be expressed in order to represent a set of objects. The next example (relation r2) presents the case of three constituents of an higher-level object (the complete description of which being given in the next section).

Finally, the alignment between objects is specified by two different values: strict when they have exactly the same temporal or spatial marks; fuzzy otherwize.

Hypernodes

Hypernodes encode subgraphs with the possibility of being themselves considered as nodes. Their structure completes the atomic node with a set of relations. Hypernodes encode different kinds of objects such as phrases, constructions, referential expressions, etc. The first example represents a NP. The node is indexed, bears a tag, a domain, an anchoring and features. The set of relations specifies two types of information. First, the NP node has three constituents: n20 (for example a determiner), n22 (for example an adjective) and n24 (the noun described in the previous section). The alignment is said to be strict which means that the right border of the first element and the left border of the last one have to be the same. The resulting structure is an hypernode describing the different characteristics of the NP by means of features and relations.

The second example illustrates the case of a referential expression. Let's imagine the situation where a person points out at a book on a shelf, saying "The book will fall down". In terms of information structure, the use of a definite NP is possible because the referent is accessible from the physical context: the alignment of the NP (n50) and the deictic gesture (n3, see previous section) makes the coreference possible. This construction results in a discourse referent bringing together all the properties of the physical object (n3) and that of the object described in the discourse <relation id="r1" label="specification"> <domain type="syntax" subtype="oriented rel"/> <edge from="n20" to="n24"> </relation> <relation id="r2" label="constituency"> <domain type="syntax" subtype="set rel"/> <node list> <node id="n20"/> <node id="n22"/> <node id="n24"/> </node list> <alignment type="strict"/> </relation> Figure 3: XML encoding of relations <node ID="n50" label="NP"> <domain type="syntax" subtype="phrase"/> <anchor type="temporal" start="200" end="422"/> <features cat="NP" agr="ms" sem type="ref"/> <relations> <relation id="r1" type="constituency"> <domain type="syntax" subtype="set rel"/> <node list> <node id="n20"/> <node id="n22"/> <node id="n24"/> </node list> <alignment type="strict"/> </relation> <relation id="r2" type="specification"> <domain type="syntax" subtype="oriented rel"/> <edge from="n20" to="n24"> </relation> </relations> </node> <node ID="n51" label="ref expression"> <domain type="semantics" subtype="discourse referent"/> <features referent="book'" color="red" /> <relations> <relation id="r3" type="constituency"> <domain type="semantics" type="set rel"/> <node list> <node id="n50"/> <node id="n3"/> <node id="n4"/> </node list> <alignment type="fuzzy"/> </relation> <relation id="r4" type="pointing"> <domain type="gesture" type="oriented rel"/> <edge from="n3" to="n4"> <alignment type="strict"/> </relation> </relations> </node> (n50). In this expression, the alignment between the objects is fuzzy, which is the normal situation when different modalities interact. The second relation describes the pointing action, implementing the coreference between the noun phrase and the physical object. This representation indicates the three nodes as constituents.

Conclusion

Understanding the mechanisms of natural interaction requires to explain how the different modalities interact. We need for this to acquire multimodal data and to annotate them as precisely as possible for all modalities. Such resources have to be large enough both for theoretical and computational reasons: we need to cover as broadly as possible the different phenomena and give the possibility to use machine learning techniques in order to produce a new generation of multimodal annotation tools. However, neither such resource, and a fortiori such tools, already exist. One reason, besides the cost of the annotation task itself which is still mainly manual for multimodal information, is the lack of a general and homogeneous annotation scheme capable of representing all kinds of information, whatever its origin.

We have presented in this paper the basis of such a scheme, proposing the notion of annotation hypergraphs in which primary as well as secondary data are represented by means of the same node structure. This homogeneous representation is made possible thanks to a generic description of primary data, identifying four types of basic information (index, domain, location, features). We have shown that this scheme can be directly represented in XML, resulting in a generic multimodal coding scheme.

Figure 2 :

 2 Figure 2: XML encoding of atomic nodes

Figure 4 :

 4 Figure 4: XML encoding of hypernodes


Z Maache-Rezzoug

I Zarguili

C Loisel

J-L Doublier

STUDY OF DIC HYDROTHERMAL TREATMENT EFFECT ON RHEOLOGICAL PROPERTIES OF STANDARD MAIZE (SMS), WAXY MAIZE (WMS), WHEAT (WTS) AND POTATO (PTS) STARCHES

Keywords: Starch, DIC hydrothermal treatment, Granulometry, Rheological properties

Study of DIC hydrothermal treatment effect on rheological properties of standard maize (SMS), waxy maize (WMS), wheat (WTS) and potato (PTS) starches

Zoulikha Maache-Rezzoug, Ikbal Zarguili, Catherine Loisel, Jean-Louis Doublier

Introduction

Starch has many applications in food and non-food industries. As an ingredient, it is extracted from only a few species such as maize, wheat, potato, rice, tapioca, and sago. Pregelatinized starches have been widely used for many foods as a major ingredient to provide thickened textures at temperatures below the gelatinization temperature. They are obtained from native or modified starch, by drum drying [START_REF] Vallous | Performance of a double drum dryer for producing pregelatinized maize starches[END_REF] or by extrusion cooking [START_REF] Barron | Structural modifications of low hydrated pea starch subjected to high thermomechanical processing[END_REF]. Other processes of physical modification have been explored to improve qualities of the starch such as annealing [START_REF] Tester | Annealing of maize starch[END_REF][START_REF] Jayakody | Effect of annealing on the molecular structure and physicochemical properties of starches from different botanical origins -A review[END_REF] and heat moisture treatment (HMT) [START_REF] Kulp | Heat-moisture treatment of starches. I-Physicochemical properties[END_REF][START_REF] Hoover | Effect of heat-moisture treatment on the structure and physicochemical properties of normal maize, waxy maize, dull waxy maize and amylomaize V starches[END_REF][START_REF] Jacobs | Evaluation of the impact of annealing on gelatinisation at intermediate water content of wheat and potato starches: A differential scanning calorimetry and small angle X-ray scattering study[END_REF][START_REF] Collado | Heat-moisture treatment effects on sweet potato starches differing in amylose content[END_REF][START_REF] Tester | Annealing of maize starch[END_REF][START_REF] Gunaratne | Effect of heat-moisture treatment on the structure and physical properties of tuber and root starches[END_REF][START_REF] Vermeylen | An X-ray study of hydrothermally treated potato starch[END_REF][START_REF] Tukomane | Preparation and characterization of annealed-enzymatically hydrolyzed tapioca starch and the utilization in tableting[END_REF]Gunaratne andCorke, 2007, Chung et al., 2009). These two latter treatments differ in the water content, temperature and processing time used. Annealing occurs under large excess of water (50 to 60%) and relatively low temperatures (below the gelatinization temperature), while the HMT is conducted under restricted moisture content (10-30%) and higher temperatures (90-120 °C). Both treatments are applied over large periods of time (10-16h). The main effects of HMT are loss of birefringence, increased gelatinization temperature, broadened or unchanged gelatinization temperature range, change in X-ray diffraction patterns, reduced swelling volume and solubility, with consequent changes in functionality [START_REF] Donovan | Differential scanning calorimetry of heat moisture treated wheat and potato starches[END_REF][START_REF] Collado | Heat-moisture treatment effects on sweet potato starches differing in amylose content[END_REF][START_REF] Gunaratne | Effect of heat-moisture treatment on the structure and physical properties of tuber and root starches[END_REF].

Annealing results in improved perfection of the crystallites within starch granules that narrows the gelatinization temperature interval; consequently, gelatinization temperatures shifted towards higher values [START_REF] Hublin | Influence des caractéristiques structurales des amidons natifs sur leur réactivité chimique[END_REF][START_REF] Jacobs | Evaluation of the impact of annealing on gelatinisation at intermediate water content of wheat and potato starches: A differential scanning calorimetry and small angle X-ray scattering study[END_REF][START_REF] Tester | Annealing of maize starch[END_REF]. The enthalpy of gelatinization remains unchanged or is moderately increased depending upon annealing conditions (moisture content and time) and the botanic origin [START_REF] Karlsson | Gelatinization and retrogradation of potato (Solanum tuberosum) starch in situ as assessed by differential scanning calorimetry[END_REF][START_REF] Lawal | Studies on the hydrothermal modifications of new cocoyam (Xanthosoma sagittifolium) starch[END_REF][START_REF] Jayakody | Effect of annealing on the molecular structure and physicochemical properties of starches from different botanical origins -A review[END_REF] in contrast to HMT. The semi-crystalline structure hal-00413220, version 1 -4 Sep 2009 of starch granules is modified by these two usual physical treatments without disrupting the integrity of granule [START_REF] Lim | Thermal transition characteristics of heatmoisture treated corn and potato starches[END_REF].

HMT starches have generally been performed at the laboratory scale and many authors have reported that such conditions produce inhomogeneous samples with lumps of gelatinized starch beside heat-moisture treated starch. For this reason, pressure is often required to ensure sufficient heating. To obtain a uniform heat distribution and rapid penetration of steam into the starch granules, [START_REF] Maruta | Reduced-pressurized heat-moisture treatment. A new method for heat-moisture treatment of starch[END_REF] improved the conventional method by creating a reduced pressure in the vessel before the injection of live steam. This method was designated by these authors as the reduced-pressurized heat moisture treatment (RP-HMT).

The DIC treatment (Instantaneous Controlled Pressure Drop) has been developed at the laboratory as well as the pilot scale [START_REF] Rezzoug | Effect of instantaneous controlled pressure drop proccess on hydration capacity of scleroglucan. Optimisation of operating conditions by response surface methodology[END_REF], for drying and texturizing of food products such as pasta products (Maache- [START_REF] Maache-Rezzoug | Study of the effect of hydrothermal process conditions on pasta quality[END_REF]. As for the RP-HMT process, an initial vacuum is applied before the treatment which is performed under high temperature/high steam pressure; the hydro-treatment step is then followed by an abrupt pressure drop towards vacuum pressure contrary to the RP-HMT treatment. This step induces a rapid modification of the thermodynamic equilibrium reached during the pressurisation (P 1 ,T 1 ) towards another equilibrium state (P 2 ,T 2 ). This new state induces a rapid cooling and the resulting temperature value depends on the vacuum pressure level (Zarguilli et al., 2009). The originality of the DIC process compared to other hydrothermal treatments is that starch is treated at an initial moisture content of 12.5% (wet basis), no hydration step being then used.

During the treatment, the heating of starch is obtained by the absorption of latent heat of steam condensation which causes an increase in the moisture content as the processing time and pressure level increase [START_REF] Zarguili | A mathematical model to describe the change of moisture distribution in maize starch during DIC hydrothermal treatment[END_REF].

The major effects observed after DIC treatment are almost similar to HMT treatment except that the gelatinization temperature range is narrowed as observed with annealing [START_REF] Hublin | Influence des caractéristiques structurales des amidons natifs sur leur réactivité chimique[END_REF]hal-00413220, version 1 -4 Sep 2009 Jayakody and[START_REF] Jayakody | Effect of annealing on the molecular structure and physicochemical properties of starches from different botanical origins -A review[END_REF]. This result suggests that the treatment firstly induced the melting of crystallites of low cohesion (low stability) which required less energy to melt. Consequently, the residual structure after the DIC treatment contained crystallites with a greater stability (cohesion) (Maache- [START_REF] Maache-Rezzoug | Structural modifications and thermal transitions of standard maize starch after DIC hydrothermal treatment[END_REF]. Preliminary studies on standard and waxy maize starches [START_REF] Loisel | Effect of hydrothermal treatment on the physical and rheological properties of maize starches[END_REF][START_REF] Zarguili | Etude de l'effet de l'hydrotraitement DIC sur les propriétés structurales et fonctionnelles des amidons de différentes origines botaniques[END_REF] showed that the thermal properties of DIC treated starch depend on the processing time and the steam pressure level. Increasing these two parameters induces an increase in the onset (T onset ) and in the peak (T peak, ) temperatures of gelatinization and a reduction in gelatinization enthalpy. The occurrence of a partial or total gelatinization was clearly attested by the decrease of enthalpy and a loss of birefringence under polarized light. The X-ray diffraction pattern confirmed the partial or total loss of the crystalline structure of native starch depending on the conditions of the DIC treatment: the relative crystallinity of hydrothermally treated maize starch decreased and the polymorphic type changed. The A-type crystalline pattern was progressively lost with the increase of processing pressure ( ≥ 2 bar), and was substituted by the V h -type X-ray diffraction pattern, corresponding to the formation of amylose-lipid complexes. At severe DIC conditions (pressure level of 3 bar), the typical peaks of A-type X-ray diffraction pattern were substituted completely by the ones of the V h -type pattern (Maache- [START_REF] Maache-Rezzoug | Structural modifications and thermal transitions of standard maize starch after DIC hydrothermal treatment[END_REF].

The objective of the present study was to describe the rheological properties of hydrothermally treated starches in the DIC process in relation to starch granules properties (size and size distribution, swelling behaviour). This study was based on rheological measurements (viscosity and viscoelasticity). These effects were investigated on starches of different origins: standard maize (SMS), waxy maize (WMS), wheat (WTS) and potato (PTS); identical treatments conditions (processing pressure and time) were applied, except for PTS. Lower pressure/time conditions were applied to potato starch due to its higher sensitivity to hydrothermal treatment.

hal-00413220, version 1 -4 Sep 2009

Materials and methods

Materials

Standard maize starch (SMS), waxy maize starch (WMS, Waxilys 200), wheat starch (WTS) and potato starch (PTS) were supplied by Roquette Frères (Lestrem, France). The moisture content of these starches during the treatment was about 12% wet basis.

Methods

Moisture content

The starch moisture content was determined by air oven at 105 °C during 24 h, according to the -707, 2000) standard method and related to the wet basis (%, wb).

A.F.N.O.R (NF V03

DIC hydrothermal treatment

The equipment and procedure of DIC hydrothermal treatment were largely described in previous studies [START_REF] Zarguili | Etude de l'effet de l'hydrotraitement DIC sur les propriétés structurales et fonctionnelles des amidons de différentes origines botaniques[END_REF]. During the treatment, 22 g of starch (12.5%, wet basis) disposed in circular containers were placed in the processing vessel (12L) in a layer of 20 cm diameter and 0.5 cm height. An initial vacuum of 50 mbar was established. As demonstrated by [START_REF] Zarguili | Etude de l'effet de l'hydrotraitement DIC sur les propriétés structurales et fonctionnelles des amidons de différentes origines botaniques[END_REF], this initial vacuum allows the air resistance to be reduced and thus facilitates the diffusion of steam into the product, consequently a rapid heating is obtained. Saturated steam is introduced into the vessel at a fixed pressure level (1 to 3 bars) and maintained during a determined processing time. In this study the processing pressure was fixed at 1 bar (100 °C), 2 bar (122 °C) and 3 bar (135 °C). The pressurisation is followed by an abrupt decompression towards vacuum (50 mbar). After the vacuum phase, atmospheric air is injected to return to atmospheric pressure for sample recovery. During the treatment, starch is heated by the absorption of latent heat of vapour condensation and its moisture content is increased.

hal-00413220, version 1 -4 Sep 2009

3.2.3.

Pasting procedure using the Brabender Viscograph

The DIC treated starches were pasted with demineralised water using a Brabender Viscograph in order to obtain starch pastes under repeatable conditions. The starch concentrations were chosen to lie within the sensitivity range of the Viscograph, depending on the botanical origin of starches. The concentrations used were 6%, 4%, 7% and 2% for SMS, WMS, WTS and PTS, respectively. The suspension was heated at 1.5 °C/min from 50 to 95 °C, then kept for 20 min at the plateau temperature and subsequently cooled down to 70 °C at 1.5 °C/min before immediate characterisation. The starch concentration was checked by drying the suspensions as previously described (3.2.1.).

Granule size distribution

Granule size determination was carried out at room temperature using a Malvern Master Sizer (Malvern Instruments, Ltd) laser scattering analyser with a 300 mm Fourier cell (range 0.05-879 µm). The starch dispersion was first diluted (1/10) with demineralised water at 20°C before and immediately after the pasting procedure in the Brabender Viscograph, and then dispersed into the sample dispersion unit (1ml/100ml water). The measure was repeated three times. The volume distribution was obtained according to the Mie scattering theory [START_REF] Loisel | Effect of hydrothermal treatment on the physical and rheological properties of maize starches[END_REF].

From each distribution, the median volume diameter (D v , 0.5 ) was presented and the swelling ratio was defined as (D/D 0 ) 3 , with D and D 0 the median diameters of treated and native starch, respectively [START_REF] Nayouf | Effect of thermomechanical treatment on the rheological properties of crosslinked waxy corn starch[END_REF]; the size distribution was evaluated using the dispersion index referred to as the span, by the following equation:

( , 0.9) ( , 0.1) ( , 0.5)

D v D v Span D v - = (Eq.1)
hal-00413220, version 1 -4 Sep 2009

Rheological properties

Flow behaviour and viscoelastic properties of starch pastes were measured at 60 °C (to avoid retrogradation) using a controlled stress rheometer (TA Instrument AR1000) with the cone/plate geometry (6 cm/2°). The starch dispersions at 60 °C were poured onto the preheated plate of the rheometer, and then covered by a thin layer of paraffin oil on the edge of the sample to avoid evaporation. For flow measurements, an up-down shear scan from 0 to 660 s - 1 (4 min) was linearly applied, followed by a logarithmic stepwise decrease from 660 to 0.01 s -1 , after equilibrium for each shear rate. The oscillatory tests at 60 °C were carried out on a new aliquot at 4% strain (linear viscoelastic range). The frequency range investigated was from 0.5 to 100 rad/s.

Results and discussion

Granule size distribution

The size distribution of starch granules was carried out before (Figure 1a) and after pasting (Figure 1b) in the Brabender Viscograph. Table 1 presents the variation of the median diameter D V,0.5 , the swelling ratio (D/D 0 ) 3 and the span, which measures the volume distribution width of starch granules, for SMS, WMS, WTS and PTS.

Before pasting the native starches exhibit a narrow size distribution of the granules, the median diameter lying between 12.9 for SMS, the smaller starch granules, to 44.6 µm for PTS the larger ones with also a minor peak at approximately one micron. These values correspond to the usual starch granule size distribution. For DIC treated starches, the size distribution curves before pasting were shifted towards higher sizes and broadened as increasing DIC conditions, with large differences depending on botanical origin: SMS being more prone to swell than WMS and WTS showing a dramatic increase at 3bar/5min. For PTS only slight modifications hal-00413220, version 1 -4 Sep 2009

were observed due to the low intensity of the DIC conditions. A progressive increase of the median diameter with the intensity of the treatment is attested for all starches. The span values increased for SMS, WMS and WTS, after DIC treatment reflecting a widening of the granule size distribution. This was particularly important for SMS (Table 1) and is probably due to the presence of a third peak at approximately 200 microns (Figure 1) corresponding to aggregates of starch granules. The different evolution of the swelling ratio (D/D 0 ) 3 clearly underlines the differences between starches: SMS and WTS present the highest swelling capacities at 3bar/5min of 105.7 and 327.6, respectively. Such a behaviour, particularly for WTS, reflects the cold swelling of DIC treated starch granules; it is not mentioned in the literature for HMT treated starches and has been ascribed to partial loss of cristallinity and subsequent enhanced capacity to hydration [START_REF] Loisel | Effect of hydrothermal treatment on the physical and rheological properties of maize starches[END_REF].

After pasting, the size distribution curves (Figure 1) of all the native starches exhibit a shift towards larger sizes as expected. The 1bar/60min treated starches, SMS, WMS and WTS, present the same distribution curve as the native ones with smoothing of the minor peak for WMS. But the 2bar/60min and 3bar/5min treated SMS and WMS show the reverse tendency: a shift towards a lower starch granules size. For SMS and WMS the minor peak at one micron was converted into a larger one, at approximately 5 µm, which disappeared for the most severe conditions for WMS. This peak may be attributed to a population of small starch granules that swell upon pasting or to the disruption of larger ones. The median diameters D V , 0.5 (Table 1) increase for native starch after pasting as expected (from 12.9 to 41.1 µm, 14.3 to 32.5 µm, 19.8 to 36.6 µm and 44.6 to 112.3 µm) for SMS, WMS, WTS and PTS, respectively. The DIC treated SMS and WMS starches present similar sizes to the native ones for the lowest DIC conditions (1bar/60min). For medium and high DIC conditions a progressive decrease is observed: the swelling ratio reaches 0.4 for SMS and WMS at 3bar/5min. This modification can be ascribed to concomitant processes of swelling and disruption of starch granules hal-00413220, version 1 -4 Sep 2009 encountered during the pasting process. For DIC treated SMS and WMS the disruption phenomenon may prevail owing to the sensitivity of starch granules induced by the treatment.

WTS exhibited an outstanding behaviour, by increasing the size of starch granules for the most severe condition (swelling ratio 1.93 for 3bar/5min). These modifications of the starch granules size distribution by DIC treatment will obviously affect the rheological properties.

Rheological properties

Figure 2 presents the rheograms of native and DIC treated starches of SMS, WMS, WTS and PTS. The flow curves are typical of shear-thinning fluids, except the ones of samples treated at 2bar/60min and 3bar/5min for SMS, 3bar/5min for WTS and at 1.5bar/5min for PTS. We also observe the persistence of the thixotropic behaviour of the starches, which may result from a disruption of starch granules aggregates under shearing. This phenomenon appeared less pronounced when the treatment conditions increased and disappeared for samples treated at 3bar/5min for SMS and 1.5bar/5min for PTS.

The Herschel-Bulkley equation (Eq.2) was applied satisfactorily from the equilibrium curves (not presented in Figure 2) according to Eq. ( 2):

.

0 n k τ τ γ = + (Eq.2)
τ is the shear stress (Pa),

.

γ is the shear rate (s -1 ), 0 τ is the yield stress (Pa), K is the consistency index (Pa.s n ) and n is the flow behaviour index (dimensionless).

The values of the flow parameters ( 0 τ , K, n) and the apparent viscosity for 1s -1 are given in Table 2. We observe shear-thinning behaviour (n<1) with a yield stress for all the native and treated starches except at 2bar/60min and 3bar/5min for SMS, 3bar/5min for WTS, and 1.5bar/5min for PTS. For these DIC conditions, the rheological behaviour of treated starches tended towards a Newtonian one with increasing flow behaviour index.

For WMS and WTS the flow behaviour index remains almost constant for all the process conditions. For all starches the increase of the process conditions causes a decrease of the yield stress and of the apparent viscosity except for WTS.

In Table 2 are presented the values of the storage modulus (G'), and the loss modulus (G'') measured at 60 °C. The suspensions of native starches exhibited the behaviour of a weak gel with G'>G'' and G' almost independent of frequency (mechanical spectra, not shown).

The storage modulus G' sharply decreased for SMS as the process conditions became more intense, while the decrease was more progressive for WMS. This effect of the DIC process on the viscoelasticity of SMS and WMS starch suspensions agrees with previous results [START_REF] Loisel | Effect of hydrothermal treatment on the physical and rheological properties of maize starches[END_REF]. WTS is the only starch which behaved in a different way, exhibiting an increase of the storage modulus with the processing conditions.

Considering the effect of the treatment on the global properties of the starch suspensions, we can observe the same evolution between the rheological parameters (yield stress, viscosity, storage modulus, Table 2) and the size of the starch granules after pasting (Table 1): a tendency to a decrease for SMS, WMS and PTS and to an increase for WTS with the intensity of the treatment. But no direct relationship can be drawn between these two characteristics as the volume fraction of starch granules is not taken into account. It is well known that the rheological behaviour of a pasted starch suspension is the result of two main characteristics: the viscosity of the continuous phase and the volume fraction of the dispersed phase constituted by the starch granules [START_REF] Doublier | A rheological investigation of cereal starch pastes and gels. Effect of pasting procedures[END_REF]. The concentrations of the starch suspensions used in that study are very close to the packing concentration described by [START_REF] Steeneken | Rheological properties of aqueous suspensions of swollen starch granules[END_REF]: i.e. the suspension can be assimilated to a packing of swollen starch granules that are responsible for the overall rheological properties of the suspensions, the contribution of the continuous phase being minored. In such a concentrated system, the storage modulus indirectly measures the rigidity of the swollen granules. The decrease of the storage modulus for SMS and WMS hal-00413220, version 1 -4 Sep 2009

resulting from the intensity of the treatment may reflect either a loss of rigidity of starch granules; or more probably a decrease of their volume fraction.

The DIC process presents some similarities with the HMT treatment as it is conducted at low moisture content between 15 and 20% for DIC (depending on the pressure) compared to the 30% usually used for HMT. All the authors state a decrease of the swelling factor (generally expressed as the volume of swollen granules to the volume of the dry starch) and of the Brabender viscosity after pasting and for SMS [START_REF] Chung | The impact of single and dual hydrothermal modifications on the molecular structure and physicochemical properties of normal corn starch[END_REF] and in a lesser extent for WMS [START_REF] Hoover | Effect of heat-moisture treatment on the structure and physicochemical properties of normal maize, waxy maize, dull waxy maize and amylomaize V starches[END_REF][START_REF] Gunaratne | Effect of hydroxypropylation and alkaline treatment in hydroxypropylation on some structural and physicochemical properties of heat-moisture trated wheat, potato and waxy maize starches[END_REF]. PTS presents the greatest sensitivity to the HMT treatment according to these two characteristics [START_REF] Gunaratne | Effect of heat-moisture treatment on the structure and physical properties of tuber and root starches[END_REF] while WTS exhibits a decrease of the swelling factor but a minor viscosity loss [START_REF] Gunaratne | Effect of hydroxypropylation and alkaline treatment in hydroxypropylation on some structural and physicochemical properties of heat-moisture trated wheat, potato and waxy maize starches[END_REF] or even a slight increase of the viscosity after pasting (Hoover and Vasanthan, 1994). The effect of the DIC treatment on the rheological properties of starch suspensions seems similar to a certain extent to the one of HMT treatment.

Conclusion

This study has shown that the rheological and morphological properties of starches from different botanical origins, standard maize (SMS), waxy maize (WMS), wheat (WTS) and potato (PTS), are influenced to a different extent by the processing conditions applied during the DIC treatment. The PTS is more sensitive to the treatment than other starches, whereas WMS and WTS are more resistant. When the processing treatments are intense the size distributions of the starch granules and the rheological properties of starch suspensions vary.

We observed a reduction in swelling for SMS and WMS starch granules after pasting which was ascribed to their prevailing disruption. For WTS the reverse result was observed. The rheological behaviour tends to Newtonian behaviour (n=1), except for WMS, with a decrease of the yield stress and the apparent viscosity as the processing conditions increase. The

Figures CaptionsFigure 1 :

 1 Figures Captions

Figure 2 :

 2 Figure 2: Flow curves of native and DIC treated starch dispersions measured at 60 °C after

Table 1 :

 1 Particle size characteristics of SMS, WMS, WTS and PTS after DIC treatment.

		(standard deviation of Dv, 0.5 =0.3 µm)
				Granulometry
			DIC conditions	Before pasting		After pasting
		Starch source	Pressure level/ processing time (bar/min)	D V , 0.5 (µm)	(D/D o ) 3	Span	D V , 0.5 (µm)	(D/D o ) 3 Span
		SMS	native	12.9	1.0	1.4	41.1	1.0	1.3
			1/60	19.3	3.3	1.5	39.3	0.9	1.2
			2/60	27.7	9.9	2.4	23.8	0.2	1.3
			3/5	61.0	105.7	2.5	29.6	0.4	1.8
	hal-00413220, version 1 -4 Sep 2009	WMS WTS PTS	native 1/60 2/60 3/5 native 1/60 2/60 3/5 native 1/5 1/30 1.5/5	14.3 17.1 25.3 39.5 19.8 22.2 30.5 136.5 44.6 45.8 46.4 54.1	1.0 1.2 5.5 21.1 1.0 1.4 3.6 327.6 1.0 1.1 1.1 1.8	1.1 1.4 2.4 1.8 1.2 1.2 1.4 1.8 1.2 1.2 1.2 1.4	32.5 36.1 22.5 23.7 36.6 36.8 36.7 45.6 112.3 114.8 114.4 104.9	1.0 1.4 0.3 0.4 1.0 1.0 1.0 1.9 1.0 1.1 1.1 0.8	1.8 1.7 1.8 1.5 1.3 1.3 1.4 1.8 1.9 1.5 1.5 1.5

Table 2 :

 2 Herschel-Bulkley parameters and viscoelastic properties of SMS, WMS, WTS and PTS pasted suspensions after DIC treatment.

		DIC conditions		Flow behaviour 60°C	Viscoelasticity (60°C ;6.3 rad/s)
	Starch source	Pressure level / processing time (bar / min)	τ o (Pa)	K (Pa.s n )	n	η a (Pa.s)	G' (Pa)	G" (Pa)	Tan(δ)
	SMS a	native	2.28 1.39 0.57 3.68	126.7	16.6	0.13
		1/60	0.68 0.72 0.58 1.41	115.4	13.4	0.12
		2/60	0.00 0.04 0.91 0.04	0.43	0.16	0.37
		3/5	0.00 0.01 1.00 0.01	3.12	0.91	0.29
	WMS b	native	0.70 0.88 0.53 1.58	1.96	1.06	0.54
		1/60	0.71 0.81 0.52 1.52	1.69	0.93	0.55
		2/60	0.31 0.26 0.62 0.57	1.12	0.74	0.66
		3/5	0.36 0.58 0.54 0.95	1.20	0.90	0.75
	WTS c	native	0.95 0.44 0.78 1.39	21.7	11.2	0.52
		1/60	0.87 0.75 0.70 1.63	30.1	12.8	0.45
		2/60	1.00 0.87 0.72 1.87	26.9	10.5	0.39
		3/5	0.00 0.03 0.88 0.03	63.5	12.4	0.19
	PTS d	native	0.77 1.28 0.57 2.05	9.70	6.4	0.66
		1/5	0.06 0.47 0.60 0.53	3.90	2.5	0.64
		1/30	0.02 0.15 0.71 0.17	4.10	2.7	0.66
		1.5/5	0.00 0.02 0.89 0.02	0.34	0.04	0.11

a 6% (w/w) SMS suspension; b 4% (w/w) WMS suspension; c 7% (w/w) WTS suspension and d 2% (w/w) PTS suspension; τ 0 :yield stress ; K : consistency index; n : flow behaviour index (τ 0 , K and n were determined from Herschel-Bulkley model); η a : apparent viscosity measured at 1s -1 .

treatment.

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