In 2004, with the album Amassakoul (Traveller), the Tinariwen band showed the world a contemporary image of Kel Tamasheq society. Its success sanctioned worldwide the cult music of the Tuareg rebellion of 1990, and propelled its cultural and political message into 'world sound', while the band joined the professional circuit of world music. While this success significantly widened its public, it also helped publicize the most critical aspects of contemporary Sahara. In recent years, many ishumar guitar bands joined the international scene, so that one can hear the words of the Kel Tamasheq about their own modernity.

The style, poetry and recent developments in this music express the historical fractures and socioeconomic upheavals that accompanied the advent of post-colonial states. The various migratory processes in which ishumar have been engaged shape the geography, music and politics of the Kel Tamasheq region of central Sahara. Independence deeply affected the Kel Tamasheq economic and political life in northern Mali and northern Niger, the places furthest from the new centralized political powers. In their vast territory, which now spans five states -Mali, Niger, Burkina Faso, Algeria and Libya -the Kel Tamasheq have been turned into outlying minorities coming under different policies and different jurisdictions of their respective states. In Algeria and Libya, assimilation policies are in force in an attempt to integrate them into the national citizenry, while in Mali and Niger they are excluded from many post-decolonization policies and various national logics depending on the region concerned. Overlaying this territorial aspect of the states is a complex diasporic process, and Ishumar music bears testimony to these people's migrations and their evolution on an intra-Saharan scale. The music takes on an original transnational cultural value when viewed in its current cross-border setup.

In this chapter I shall show how the music reflects current Kel Tamasheq mobility and life experiences, and how its emergence during the region's post-colonial phase relates directly to complex and many-sided migration patterns. The music arose out of very special conditions that were present in the Kel Adaŕ diasporic community in the 1970s and 1980s, namely a combination of social marginalization leading to the formation of various migratory social movements and a revitalization of poetic and musical forms. We shall see how it can be understood as a new formulation of various traditional musical and poetic genres set against specific social criticism and Kel Tamasheq political speeches. I emphasize how the music relates to the territory, both in the lyrics of the songs and in the local modes of distribution.

I shall not deal with ishumar music as world music. In fact, I shall consider it as a social and artistic display that proceeds from an uninterrupted and multidimensional process. Its recent Western dimension becomes significant when comparing the multiple social meanings it embodies in diasporic communities, both in current national contexts and on the world scene. The Kel Tamasheq pop guitar is rising in popularity and various media are involved in its circulation, diffusion and commercialization. Yet the cyber network penetrating the Sahara and Sahel tends to make them telescope.

I shall recall how the marginalization and pauperization of the Kel Adaŕ in northern Mali in the 1970s revitalized and transformed cultural and musical expression. Invented during a socially destabilizing diasporic experience, the Kel Tamasheq guitar, however, emerged at at the junction of closely related musical traditions of West Africa, in the Niger bend, which were redefined when the guitar was introduced into the region. In some respects, and despite its original features, this music is part of the West African modern guitar penetration into Mali at the end of the 1960s.

The ishumar guitar can be seen as a hybrid that reshapes several musical styles or types, while producing a social critique and political discourse from the history of the Kel Tamasheq nationalist movement. I shall then look at the evolution and assimilation of this musical type into Mali and Niger.

Last, I shall focus on some aspects of its worldwide distribution, namely its cyberspace music circulation, showing with a few examples how it illustrates and reproduces the different imaginary resources that emerge and circulate both in the world music of the Western world and in the transnational culture of the ishumar.

THE EMERGENCE OF THE ISHUMAR GUITAR IN POST-INDEPENDENCE KEL TAMASHEQ DIASPORIC PROCESSES

This music emerged in the mid-1970s from socially and politically marginalized Kel Adaŕ communities in central Sahara. The 1963 Kel Adaŕ revolt opposed Malian state sovereignty. It was brutally repressed and the army slaughtered hundreds of people and their livestock. Military rule was imposed on this region until the end of the 1980s. [START_REF] Boilley | That desert is our country: Tuareg rebellions and competing nationalisms in contemporary Mali (1946-1996)[END_REF] Many Kel Adaŕ groups fled to the Ahaggar in Algeria with numerous orphans. Family dispersal and social marginalization are some of the consequences of this diasporic movement.

For the Kel Adaŕ, this historical fracture with the past during the postindependence period was at the start of their cultural and identity reconstructions. It forced on them a new form of mobility that until then had been unknown within their very ancient tradition of mobility. This was the time of the exodus, on foot, towards southern Algeria. In small groups, these nomads, fleeing the army after losing their livestock in the droughts of 1968-74, would walk to Tamanrasset with only a five-litre can of water to help them brave the 700-kilometre journey to the wilaya. This was what the first ishumar referred to at the time as the 'can road'. Successive waves of young men would leave home to start a new and adventurous way of life. They faced hostile authorities and state borders that deprived them of any citizenship. Consequently, they would cross the borders illegally or, as they say in French, 'en fraude' (locally rendered into afrod). The word afrod has now come to refer to their various cross-border smuggling activities.

They started smuggling on foot, operating a kind of subsistence economy during the droughts of the 1980s, under dangerous conditions. [START_REF] Elelli | L'initiation d'un ashamur[END_REF] At the time, the word ashamur referred to various exclusionary forms of citizenry and education, which all Kel Tamasheq shared, in Mali as well as in Niger, as mentioned in the following verse: Wur leŕ elkad faw iktaben, kunta weddeŕ I ishraden: '[On the road When two extreme droughts (the first from 1968 to 1974 and the second from 1984 to 1986) shattered the pastoral economy, most nomad families took refuge in urban centres. Shantytowns sprang up and became de facto ghettos for destitute refugees around Arlit, Niamey, Gao, Agadez and Tamanrasset, and on the borders between Algeria, Mali and Niger. Young men, mostly Kel Adaŕ from Mali, or Kel Aïr and Kel Azawad from Niger, migrated to the main cities (Tamanrasset, Ghat, Sebha and Ubari) of the Kel Tamasheq regions in southern Algeria and southern Libya where they formed informal diasporic communities and from which the Kel Tamasheq political movement emerged in the late 1970s. [START_REF] Boilley | dépendances et révoltes: du Soudan français au Mali contemporain: hommes et sociétés[END_REF] The ishumar worked as seasonal labourers in Fezzan towns. Some migrants took on Libyan nationality and were integrated into the local economy, while many others were relegated, without rights to own land or to open a shop, bank or business, to the informal Libyan economy, which the official public economic system dominated. Even though Kel Tamasheq were, in theory, welcome in Libya, many did not want to adopt Libyan nationality, or could not because they were unable to prove their previous national origin, so their personal status remains uncertain. 4 It kept them on the margins of the social system in Libya, though they did have access to medical and educational services. Sebha is Libya's entrance point for migrants from the southern Sahara. Where migrants live depends on their national origins. [START_REF] Pliez | Villes du Sahara, urbanisation et urbanite dans le Fezzan libyen[END_REF] Tuareg refugees and seasonal workers usually live in El Cambo (the camp), a huge ghetto close to the airport track. Kel Tamasheq diasporic groups in Ubari live in a district called Tilaqqin, close to an outlying area where state farms were created in the 1970s and 1980s. Because they needed each other's support to secure housing, job opportunities and access to financial aid, and wished to share the information they gleaned during their many trips between the various localities in their range, the ishumar started to develop new solidarities outside their lineage affiliations. Cross-border travel in four-wheel drives and risk control typify their mobility and connect them to several identities. In this context, cars take on a particular significance and are vital in their new cross-Sahara and cross-border geographical mobility. [START_REF] Kohl | Going off-road: with Toyota, Chech and E-Guitar through a Saharian borderland[END_REF] The ishumar provide a link between the various diasporic groups by keeping in touch with their original groups and generating a wide transnational network. More generally, these groups of migrants joined forces with other Saharan migrants involved in the recent increase in central Saharan urbanization, [START_REF] Pliez | Villes du Sahara[END_REF] and this proved decisive for the dissemination of their music.

THE EMERGENCE OF THE PROTEST SONG BETWEEN TAMANRASSET AND SOUTHERN LIBYA

The Kel Adaŕ took with them their festive spirit (ezuhu) and their music. The vitality of Kel Adaŕ vocal and poetic traditions that used to celebrate nature, bravery and above all love, now serves other realities, even though its poetry is still used for critical and educational ends. Throughout the region, the ancient and living tradition of the art of flowery language, following the example of other Tuareg groups, is renowned for the high quality of both its tinde and iswatt, namely songs mixing women soloists with a male chorus that are sung at evening gatherings and are very popular in the nomad community. Massive mobility generates major changes in musical culture. Far from reducing their creativity, the general pauperization of the Kel Adaŕ and the fact that they are excluded from the new Malian entity, stimulate this creativity, opening it to new musical practices and new formulations of traditional genres. In the 1970s, the plastic can that saved migrants from thirst on their journeys became the drum for musical evenings in the shantytowns, while the children of Malian Tuareg refugees in Algeria, mainly in Tamanrasset, turned it into the 'guitare-bidon' (canguitar). [START_REF]The 'guitare-bidon' is a five-or ten-litre can fitted with a wooden neck and metal strings or cables[END_REF] There, the Kel Adaŕ form both the oldest and most important Tuareg community in what was then a rapidly growing district ghetto called Tahaggart-shumera, which is separate from the city's local Kel Ahaggar suburb. Bellil and Badi 9 describe how the Kel Adaŕ turned this stigma into cultural dynamism, protest and conscious vitality to address the crisis through which they were going. The authors describe the festive practices called zahuten (singular ezuhu) (entertainment parties) as very remote in their social and political expression from the formalism of the local performances on the increase in the 1970s with the development of Western tourism in the Ahaggar.

In Tahaggart, they organized around a series of tinde festivals, led by women singers whose talent and strong personality made them leading figures among the ishumar, as Lalla, the most famous tendé singer from Adaŕ origin. Mortar-drum and vocal tinde performances are one of the most popular Tuareg musical traditions. Some sources 10 place its origin in the Adaŕ, among the vassal tribes, and assume that it spread from there into the Ahaggar and Niger. As a reformulation of traditional rural tinde, it has a cultural reproduction value in the context of this social crisis. These parties (zahuten) gave mobile and flexible youths a strong anchor in their travels and activities. They also provided a forum for free speech and debate on the Tuareg situation in their countries or among exile communities. The resources to finance the series came from the informal economy of the ishumar, whose incomes effectively alleviated the effects of the impoverishment the drought had brought. [START_REF] Bellil | Evolution de la relation[END_REF] In Tahaggart tinde the songs talk about the sore ishumar walking to Libya:

Oh mother! Since I left for Libya persevering, I finally arrived! But I cannot settle in no way I search for the necessary money through all means

But it desperately refuses to accumulate. [START_REF] Tinariwen | [END_REF] In the 1970s, the neo-tinde of Tahaggart-shumera ushered in the musical alguitara genre's poetic forms and stylistics of social protest and political mobilization. By the end of the 1970s, it had simultaneously made an appearance in the Kel Adaŕ diaspora around two main figures, Ibrahim ag Alhabib and Inteyeden ag Ablil, founders of the group Tinariwen.

They had both grown up in a musical and cultural environment containing a mixture of urban tinde, 'guitar-bidon' and women's refugee poetry. One should note that the Kel Adaŕ have no lute tradition (teherdent), a war genre specific to a group on the Niger bend in Mali. That specific musical genre would, however, undergo some developments when the ishumar became the first musicians to criticize and then 'compete' with it at the beginning of the 1980s. To understand the source of this criticism, it is necessary to recreate the Sahelo-Saharan musical scene of the time with its many status changes and migratory-linked reformulations. This applies specifically to the dissemination of teherdent music.

According to Card Wendt, [START_REF] Wendt | Tuareg music[END_REF] in its native region between Timbuktu and Gao, the teherdent threestringed lute tradition constituted one of the most remarkable characteristics of the musical patrimony. Songhay, Hausa, Moorish and Kel Tamasheq used to perform it, though the latter are the only ones with a former lute musical tradition. Instrument practice is hereditary and restricted to specific social groups among which status and social roles are similar in all these neighbouring groups.

The Kel Tamasheq word for instrumentalists and professional dancers who in a group perform a poetic critique or panegyric accompanied by teherdent is aggiwen. At such traditional performances money is collected and distributed to the panegyric singers whose musical role is closely linked to the promotion and values of the notability of social groups.

Praise singing and money are intimately linked to performing social music. Terhedent music spread to other Kel Tamasheq areas when the first major migrations of drought-stricken Malian Kel Tamasheq occurred in the late 1960s: Many musician-artisans started performing outside their own lineage affiliations in order to provide for themselves, since their former employers could no longer support them. This is when musicians changed style to perform in Niamey and then in other towns in Niger up to Agadez where teherdent was first heard in 1971. Teherdent has become the urban dance music for a cosmopolitan and multi-ethnic public. It provides entertainment that connects several cultures [and] many people can relate to its public performances because of the similarities in their modern forms between Hausa, Djerma, Fulani, Songhay, Tuareg and other West African repertoires. 14 Malian teherdent players were active in most urban centres across Sahelo-Saharan borders from 1976 onwards. Teherdent music reached Tamanrasset in 1974, to the delight of Tuareg exiles who found it relieved their homesickness, when the takemba rhythm became the new fashionable style.

The introduction of modern technology used for recording and reproducing sound in Africa diversified the social uses of music and made it more widely available. Tapes were exchanged and the circulation of local cultures generated an informal market for music recordings. Ishumar were also captivated and virtually impoverished themselves paying musicians to liven up their evening parties. [START_REF] Bellil | [END_REF] with female and male musicians travelling with their cassettes, various musical genres competed and crossed with one another. Whereas tape recordings were largely responsible for making aggiwen popular, ishumar used them to promote their political poetry or discourse. At the end of the 1970s, tape-recorded speeches from Libya reached Tahaggart referring disparagingly to teherdent music, criticizing its mollifying effect on the minds of young people, and calling upon them to react and to raise awareness among the youth of their situation and of their political rights. 16

TINARIWEN, THE VOICE OF ISHUMAR CULTURE

The Tinariwen band joined the Tuareg organization that was created in Libya between 1978 and 1980. The leaders encouraged them and supplied them with guitars and equipment. Militant poets offered them several compositions that they turned into songs:

Friends hear and understand me

You know, there is one country One goal, one religion And unity, hand in hand Friends, you know there is only one stake to which you fettered are And only unity can break it. [START_REF]Imidiwen segdet teslem[END_REF] They started to experiment with the instrument's acoustics by adapting melodies from the traditional vocal repertoire and inventing a set of guitar rhythms inspired by some of the syncopated rhythms of the tinde. The basic form is a responsory song between the singer-guitarist soloist and the male or female chorus, interrupted with interludes of variable length, improvised on the melodic line. The music is testimony to a major stylistic novelty produced by crossing a melodic and polyrhythmic (guitar and tinde) instrument and a responsory song between the soloist and the choir.

Let us rise, do not to let the time escape us Together, let us rise and let us join up

Please my brothers; let us unite in order to up rise. [START_REF] Tinariwen | [END_REF] The performance was uneven and focused on social and historical events. When the women joined the group, the feminine musicality of the camps mixed splendidly with the sound of the guitar, the tense responsory song by the female chorus, the strike of the tambourine player and the rhythm of yeqqes (syncopated hand-clapping, which is close to the Moorish style but also part of the Kel Adaŕ musical tradition). The group worked more as a flexible association serving the needs of the political movement than as a professional musical band, which, before the ishumar guitar came out, Kel Tamasheq looked down on because of the low regard with which teherdent music was held.

Tinariwen tunes immediately became the musical cult of the rebellion and of all youth in exile both in Algeria and Libya. It spread to the migrants' native regions (Mali and Niger) thanks to tape recorders, cassettes and the underground strategies of mobility and diffusion. There were many repeat performances and exchanges of recordings among the ishumar, but the interpreters were careful to separate the text from its sung performance to ensure that the message was clear. The oldest recorded cassettes contain, by way of an introduction, a recitation of the entire text of the song in the form of a mobilizing discourse. This practice characterizes performances during the first decade and underlines the strong proximity of the music, at its beginnings, with the intention to spread the social and political discourse it conveyed. The song aghregh shatma n-etilla aghrem [START_REF][END_REF] is an illustration of this dialectic even in the text:

I call to my sisters in all towns

Goose pimples on my skin because this is the time for the return of my brothers Who were trained long ago The last instructions were given out of town

If the BBC is standing by, it will call Mali and broadcast: "Beware! You will soon burn! They have spent years sleeping with this anger Because of those elders you killed Those animals you burnt". 20 Cassettes were as much a medium for politics in the ishumar environment as they were an efficient way of disseminating a nationalist discourse beyond the borders of the diaspora. The group linked its performances to the history of the Tuareg movement from the beginning of the 1980s to the middle of the 1990s. [START_REF] Belalimat | Le chant des fauves: poésies chantées de la résistance touarègue contemporaine du groupe Tinariwen[END_REF] Its protest songs produced national and regional mobilization for the rebellion as much as they justified it. The power of the ashamur song at the time relied on several mechanismsan emphasis on the historic country (imidiwan win akal-in/nak ezaghagh el-ŕurba), an allegory of the reinvested homeland (as-sawt el wahush), constant reaffirmation of social ties and family links transcending the absence, the construction of political solidarities, and a call to action. [START_REF] Belalimat | Qui sait danser[END_REF] All these themes are performed through the subjectivity of a narrator.

The image of the historic home as a fatherland is a recurring theme in the songs suggested by the word tenere, which has two meanings in the Tuareg language -wasteland and solitude. In this last meaning it can be synonymous with esuf, which has several meanings -nostalgic solitude, melancholy, deserted and non-domesticated space. Esuf, a symbolic notion of traditional poetry, is reinvested in the idioms of ishumar wanderings and of the barren places they have to cross each time they have to move. [START_REF]Esuf is one of the privileged themes in Ibrahim ag Alhabib's songs: alkhar desuf on CD Tinariwen[END_REF] Writing on the relationship between music, four-wheel drives, crossroads and confinement, Ines Kohl [START_REF] Kohl | Tuareg in Libyen[END_REF] described its identical joint articulation for the ishumar of Niger. In many respects, ishumar music is burning melancholic off road music. Both meanings of the word tenere merge in their experience of exile, illustrated by one of the most famous and oldest songs. The name of the band recalls this ambiguity of a territory, or rather territories (tinariwen: countrysides, deserts), travelled through and imagined as being both the cross-border territory of exile, and the imagined one of the homeland (akal).

I live in deserts [tinariwen]

his band and did his basic training with Takrist-n-Akal. Hamid Ekawel, an excellent singer-interpreter from Nigeria also learnt tuareg guitar music in Libya thanks to Mohamed Japonais lessons. The group named Toumast assembled student musicians from the Tamesna region (in Niger).

In the mid-1990s, once the rebellion in Niger and Mali had died down, the alguitara performers adjusted to the new context of peace negotiations and the concerts lost their clandestine and subversive character. Young people in the urban areas took to it immediately; new groups were formed and the ishumar guitar became the most popular musical genre among the Kel Tamasheq youth. The whole Tinariwen 1980s repertory became the musical heritage and musical background for younger generations, a hundred of songs circulating, performed and transmitted.

The 1990s marked the transition from highly politicized underground music to a popular music with which the youth could identify and make their own. Thus, in the post-rebellion period (from 1995 onwards), most performances 'promote transformation from protest to dialogue, although composers, performers and audiences express ambivalence about this process'. [START_REF] Rasmussen | Moving beyond protest in Tuareg ishumar musical performance[END_REF] In 1995 the Takrist-n-Akal band, which Abdallah ag Oumbadougou formed in 1988, was asked to perform in Agadez and Niamey for the first time. It accompanied various evening performances officially depicting the dissident Tuareg movement's reinstatement in the country. These included one at the French cultural centre in Niamey and another at the UDPS [START_REF]of alguitara music being brought into this political party's mobilization process in Niger, see also Rasmussen[END_REF] gala performance to commemorate the signing of the peace agreements.

As in Mali, in next to no time the genre became the music of the Tuareg youth of the north as well as of the capital, where it is as much an expression of culture and identity as a form of entertainment at cosmopolitan gatherings. The bands blossomed and opportunities to perform expanded. The music, openly based on mixing genders and close to the former takemba teherdent style the previous generation had so enjoyed, became the mainstay of young people's dances and festive practices. The music virtually took over in the private sphere (such as at marriages and naming ceremonies) and the performances assumed several roles and functions.

In Libya, several amateur groups of the generation that was born in the 1980s, such as the Tilaqqinbased Akori band (Shout of Alert), still play in Tilaqqin, Sebha and Ghat. The musical vitality of the diasporic groups in Libya is, albeit to a lesser measure, comparable in its effects to those of the Kel Adaŕ in the Algerian south during the 1980s. For example, it is especially the young guitarists of Niger who perform in the refugee quarter of the city of Ubari. They are the musical representatives of the cultural and identity discourses to the Libyan Tuareg youth of Fezzan, whose linguistic assimilation into Arabic culture is well advanced.

The ishumar guitar songs may have a linguistic and cultural value for the young Libyan Tuareg (Kel Azjer) bathed in a Middle-Eastern television culture.

GUITAR TUNES BETWEEN SEVERAL WORLDS

In 1999, a project for a CD was born in Mali following a meeting between the French band Lo'Jo and Tinariwen. [START_REF] Tinariwen | Radio Tisdas Session[END_REF] They launched the Festival in the Desert at Essakane (near Timbuktu), conceived of as an occasion for global exchanges and meetings between local, Malian and Western musicians and devoted to the Malian peace process. Within a few years Essakane had become the place for cultural and musical tourism in northern Mali and a cultural mechanism through which to promote reconciliation and a discourse on development in the northern region. It is also a place for intercultural connections with multiple dimensions, which we cannot start to approach here in detail.

In 2003, the punk rock Navaro band Blackfire and Tinariwen met there again after having fraternized at a German festival. In 2004, two different groups met at the festival, Tuareg guitar and traditional Woodabe of Niger, who merged into Etran Finatawa (Stars of the Tradition) and performed on the stages of the international circuits of contemporary world music. The festival brought together many different trends in teherdent music. It not only welcomed Ali Farka Touré in 2003, but also became the main venue for local bands in search of Western producers.

The increase in the number of cultural festivals [START_REF]), the Ségou festival and the Tessalit camel fair[END_REF] over the last few years is evidence of a strong desire to integrate national development policies through culture, allowing rural communities or peripheral and enclaved areas such as the Adaŕ to promote their region on the national scene.

In 2004, Tinariwen's second album came out in the Western world and became a worldwide success.

Honoured by awards, hailed by dithyrambic critics in the rock and blues press all over the world and welcomed by some big names in the pop and rock guitar world, the melancholic and rural Tinariwen style has become a source of inspiration and a fascinating new horizon for some rock and blues [START_REF] Went | to the renowned Montreux Jazz Festival in[END_REF] stars, well beyond the world music category where it was conventionally classified at its onset.

Musically, the Western production of the group's music, even if it was given a more rockish tone than its original style, presents a large variety of musical forms. Today it ranges from fragments of tinde scoring (Ahimana; Tinariwen 2004, track 4) to borrowings from rap music (Agadez In Gall from Aman Iman; Tinariwen 2007); Aratane'n Tinariwen (Tamikrest) or to reggae (Rasta man aridal). 33 In Niger, the Western production of the music Takrist-n-Akal inhumere has the added advantage of funding a project to develop Abdallah ag Oumbadougou's local school of music in Arlit at which guitarists are taught and can rehearse. The Desert Rebel project brings together several different musicians from the French musical scene, all stemming from various rap styles (Imotep of the Marseilles rap band, IAM) or from the French-Maghreb fusion, with the participation of Amazigh Kateb from the Gnawa Diffusion group (a major band on the French scene of the 1990s and 2000s that revisited some popular and learned repertoires from the Maghreb while being very influenced by the musical raga culture of the French suburbs).

The Tidawt, a band taken on by Hasso, performs regularly in the United States and Europe, thanks to the support of the Nomad Foundation, 34 dedicated to the preservation of cultural and artistic traditions in Africa. In 2006, Tidawt recorded with the Rolling Stones, the forthcoming 'Stones World' Album. Beneath this glittery image, the very same band sings in Niger to persuade the youth to be patient (Song Tazedert, Tidawt) or to speak of their resentment ('In this world that frightens, there are more people who destroy than people who build'), even of their impotence: 'My friends, this life is difficult, that you say the truth or that you lie, you always have twists' (Tidawt). Since the new uprising in Aïr (in Niger) in 2007, war songs are again resounding. The important recently discovered uranium resources of the region weigh heavily on the conflict and on the future of the breeders in the north of the country. The musicians of Takrist-n-Akal express their anxieties in the face of this situation: 'We are only breeders and our basement attracts the world' and take back part on it as musicians. [START_REF] Wanaghli | [END_REF] Since the beginning of this century, in fact since joining Western music marketing networks, there have been many changes in how the currently most popular musical genre is being produced and distributed to Tuareg country. These include changes in public performances, production and distribution, as well as in its own characteristics. Today there are more than 15 guitar bands of various levels of professionalism, experience and repertoire, of which at least ten are listened to in the West through circuits that are more or less linked to the world music production system.

Paradoxically, despite their success on Western airwaves between 2004 and 2007, Kel Tamasheq guitar bands have no national reputation in Mali or Niger and theirs remain a music characterized by its distribution within the community. The peculiarity of international diffusion is such that, contrary to other genres of West African music on the international circuit, Kel Tamasheq guitars suffer from a shortage of production frameworks in West African music publishing; it remains very much on the outside of the national markets of publishing and production. Though CDs do exist, artists still record on cassettes to advertise their music to the local market. Recordings in Bamako studios are an impossible luxury for northern Malian musicians who are not integrated into the professional networks of rich southern Malian musical production, the jewel of world music catalogues. Their breakthrough on that market is due very much to Tinariwen and its role in developing the Essakane festival in Mali at the beginning of the 2000s. Through a somewhat anachronistic process of media exposure, the world success of Tinariwen and the group's tour not only drew attention to the struggle in the 1990s, but also made far more people aware of the plight of Kel Tamasheq youth today.

With the development of cyber communication technologies in the Sahara and Sahel, Kel Tamasheq guitar bands are played on the internet and exchanged as digital formats, thus generating a new system of North-South/South-North free exchange. Nevertheless, for the ishumar of trans-Saharan space, tapes are still the best option. They are more appropriate for desert travelling conditions and are especially compatible with the tape player in four-wheel drives, a valued mode of transport endowed with important symbolic value in ishumar mobile culture.

CDs produced in the West are thus reintroduced to transnational musical networks of exchange in social circulation. On the other hand, copies of CDs produced in Europe are resold on the informal urban music market on SD Cards and MP3 formats. This dematerialization of the music and the exchange practices underlying it, mostly affect Kel Tamasheq urban and student communities.

On the internet they become spaces for exchanging and sharing digitized musical files on websites, for they have been turned into big suppliers and media generators of identification through distant cultural or like processes.

And going as far as the ring tones of mobile phones and Bluetooth exchanges, Kel Tamasheq pop guitars have entered the era of digitalization. The web offers several examples of the worlds these songs cross. In Morocco and in Europe, the websites of the Berber cultural movement advertise current Kel Tamasheq musical events. Since the events in Niger, these now include war songs, or songs dedicated to the deaths of civilians the army has massacred, or about fighters who have 'died as martyrs'. 36 In Libya, networks among the Mali and Niger diaspora are actively creating websites dedicated to valorizing -in Arabic -the transnational culture, identity and speech of Kel Tamasheq people. Today, ishumar guitar tunes can be understood as music performed in between national integration processes and Saharan transnational political Kel Tamasheq agencies. This process implies a fundamental questioning of the socio-economic development of the regional states' Saharan suburbs. The ishumar's transnational mobility, such as I have tried to sketch it in this chapter, questions whether there is in fact a need to integrate these cross-border societies into national economic projects. The history of the circulation of Tuareg music since independence shows that mobility is not an empty word insofar as the social and economic strategies of Saharan peoples are concerned.

The movement of global broadcasting shines more than it informs. Nevertheless, it accommodates a common imaginary background and provides a cultural reality potentially shared with a global audience. It indirectly casts light on the political and cultural stakes of the past and future struggles of a youth in search of the political and economic means to build a future. Today, the ishumar participate, through this music, in the dissemination of their desert culture of migration to the diasporic groups, to Kel Tamasheq nationals and to the world scene, in representations and evolutions that represent some of the stakes in the globalization of cultural exchanges.

Notes

  to exile] We have no [identity] papers, no education [literally books] other than our amulets.' A mix of economic and political factors in the context of a difficult and protracted post-colonial transition, which affected migration patterns in general, sparked off this particular diasporic movement of southern Kel Tamasheq people living on the peripheries of the newly independent states. During the 1970s and 1980s, when severe droughts exacerbated already difficult political and economic conditions, new migration waves originated from the Azawaŕ valley and Tamesna (in Niger and Mali respectively), from Aïr (in Niger) and from Adaŕ (in Mali). At one time or another political exile, seasonal labour migration and droughts affected most Kel Tamasheq people.

  The hybrid creative process, in an urban context, of combining the modern instrumental tone of the guitar with the female vocal melodic repertoire of the rural tinde constituted the point of musical innovation and appeared as a musical revolution for the Kel Tamasheq youth:Youth of Sahara, we warn youDo not believe that we are unableTo reverse the procedure This new world, we are crushed there Because it woke up first I tell you, courage, courage, courage!

Where there are no trees and no shade

Veiled friends, leave indigo [turban] and veil

You should be in the desert

Where the blood of kindred has been spilled That desert is our country [akal] and it is our future Kel Tamasheq, how are you? Where ever I am, I think about you. [START_REF] Song From Tinariwen | Translated by Lecocq, 'That desert is our country[END_REF] The close links between state borders and relegated national citizenships appear in the texts as metaphors where roads are described both literally and figuratively as economic and cultural dead ends. Nearly fifteen years after the peace agreements, the returns of the rebellion in 2006 and 2007 in both northern Mali and northern Niger are not a sign of successful integration in those Saharan areas in both countries. Hindered walking represents the current political dead ends. [START_REF] Claudot-Hawad | A nomadic fight against immobility: the Tuareg in the modern state[END_REF] walking alone in the black night, afrod, leads to the maquis and to war, as this song seems to tell us:

Roads are cut, borders closed With no mount, walking is painful

We walk in the black night My heart illuminated by the obvious My friend with whom I shared so many ordeals Our shared words entered obscurity Our grief is sour, we endure, we are relegated far behind Because I drank many times the water of secrecy Today I am in the mountains and each one of us is on one's guard. [START_REF] Terakaft | [END_REF]

ISHUMAR MUSIC IN ITS NATIONAL CONTEXTS

In the 1980s, the genre gained widespread acceptance, especially among the ishumar from Niger living in Libya. It was an intense performing times for Tinariwen, also an intense teaching period to next generations meeting in South Libya. Specially Mohamed ag Itlal, aka Japonais, was one of the most active guitar teacher for young ishumar. A troop of ishumar guitarists from Aïr (Niger) called Takrist-n-Akal, 'the land building', appeared in 1988 around Abdallah ag Oumbadougou. At the end of the 1980s, the young Hasso, the future guitarist leader of the group Tidawt from Agadez, joined


Amelia Carolina Sparavigna

Evaluating Urbanization from Satellite and Aerial Images by means of a statistical approach to the texture analysis

Keywords: Image analysis, 2D textures; texture functions, satellite images, aerial images

Statistical methods are usually applied in the processing of digital images for the analysis of the textures displayed by them. Aiming to evaluate the urbanization of a given location from satellite or aerial images, here we consider a simple processing to distinguish in them the "urban" from the "rural" texture. The method is based on the mean values and the standard deviations of the colour tones of image pixels. The processing of the input images allows to obtain some maps from which a quantitative evaluation of the textures can be obtained.

Introduction

The processing of images by means of a statistical approach can be rather simple, in particular when it is mainly based on quantities such as the mean values and the standard deviations [START_REF] Haralick | Statistical and structural approach to textures[END_REF]. Besides for its simplicity, this approach is valuable because it allows a very fast elaboration of images, being therefore quite useful when we need to analyse a large number of images. We used it, for instance, for investigating the texture transitions in liquid crystals [START_REF] Montrucchio | A new image processing method for enhancing the detection sensitivity of smooth transitions in liquid crystals[END_REF][START_REF] Sparavigna | Texture transitions in the liquid crystalline alkyloxybenzoic acid 6OBAC[END_REF][START_REF] Montrucchio | A novel order transition inside the nematic phase of trans-4-hexylcyclohexane-1-carboxylic acid discovered by image processing[END_REF]. Here we modify the method to have it suitable for the study of satellite and aerial images, from which we can measure the evolution of the local urbanization. Some examples of the method, on sites in Italy and in England, will be given using the images we can find in Google Earth. In fact, the Google Earth software features historical data on several places around the world. We have, among the software icons, the clock icon that we can select to view the historical imagery in a time series. It is enough to select the icon and use the given sliding tool to view the progress of the selected location through time. Using Google Earth and its gallery of images, we can time travel to see the natural evolution of a place or the development of urban areas [START_REF] Monkkonen | Using online satellite imagery as a research tool mapping changing patterns of urbanization in Mexico[END_REF][START_REF] Yu | Google Earth as a virtual globe tool for Earth science applications at the global scale: progress and perspectives[END_REF][START_REF] Taylor | Mapping public and private spaces of urban agriculture in Chicago through the analysis of high-resolution aerial images in Google Earth[END_REF]. Let us note that the software is archiving, besides the satellite images, also some aerial imagery. In particular we have a large part of England and some of the Italian towns, covered by aerial images of 1943 or 1945. In this manner we can easily evaluate the processes linked to urbanization of such covered areas, after the World War II. In the following section we will illustrate the method and give some examples. We will see that it is possible to distinguish the "urban" texture from the "rural" texture in the images. In fact, from the input images we are obtaining the maps which allow a quantitative evaluation for distinguishing the textures in them.

The statistical method

The image analysis method we use here can work on any colour image. However, instead of considering a full RGB picture, let us involve for computation the corresponding grayscale image. The starting point is therefore a RGB image of y x N N × pixels, reppresented by the three-channel brightness function:

. [0,255] = , ] [1, ] [1, = , : 3 3 2 N N ⊂ ⊂ × → B N N I B I b y x
After, we consider a grey-tone map obtained by giving ) ( ) ( )

∑ = = 3 1 ) , ( 3 1 )
P P P P P P j i M j i j i , , = , Σ ξ
Among the values ( )

P P j i , ξ
we determine the largest one, Ξ . Then, we define a colour tone accordingly:

( ) ( ) Ξ × P P P P c j i j i , 255 = , ξ ξ (*)
Then, from the original image we create a map made of squares with size P P × having a specific colour tone given by (*). Let us stress that, in each square, the pixels have the same colour tone (*). We have a bright square, when the local standard deviation is large. This happens when the pixels of the original image in the given square have oscillating values. In the case of satellite images, this corresponds to an area containing houses and streets. The dark squares are coming from the large areas in the original images, which have more homogenous grey tones. These areas are corresponding to fields for agriculture. Let us see some examples.

Torino and agricultural land near the town

Let us consider two images from Google Earth (Figure 1). On the left we can see the central part of Torino, and on the right, some fields near the town. Let us apply the statistical method previously discussed. We have the following two maps given in the Figure 2.

Figure 2: The maps made of squares obtained from the panels of Figure 1, according to the statistical method previously discussed.

As we can see from the map on the right in Fig. 2, there are also evidenced some of the edges among fields. The homogenous areas turn into black areas. The two maps are evidencing the different textures of urban and rural areas: the urban areas have a large number of bright squares, homogeneously distributed, whereas the rural land has a large number of dark squares.

Counting the percentage of the bright squares can be a possible method for a quantitative measure of urbanization. Let us stress that the proposed approach is different from the simple pixelation we can obtain from a software such as GIMP, the GNU Image Manipulation Program. The GIMP pixelation of the panels in the Figure 1 are given in Figure 3. The GIMP pixelation is not useful for a quantitative evaluation of urbanization.

Figure 3. Pixelation of the images in the Figure 1 obtained using GIMP.

Comparing urbanization in 1945 and 2004

Now, let us apply the method for evidencing the evolution of the urbanization through the satellite images. For the analysis of the urban evolution we consider a location in England. The town is Carterton, which is today the second largest town in West Oxfordshire. The 2011 Census recorded the parish's population as 15,769 [Wikipedia]. In 1945, the town was smaller than today, as we can see in the aerial image of 1945 (see Figure 4). Figure 5: These two maps, obtained by the statistical approach given in the section 2, are showing that the urbanization changed. From the map on the right, we deduce that the original image has a large part of it which is containing local oscillations of the grey tones, oscillations which correspond to the presence of houses and streets. These oscillations are increasing the standard deviation of the squares.

The areas in the map which are black correspond, in the original images, to areas covered by a homogenous color tone, that is, to the rural fields.

In the Figure 4 we have two grey tone images of the same town in England recorded in 1945 and in 2004. The image on the left is an aerial image and the image on the right a satellite image. We can apply the approach discussed in the section 2, for determining the maps of squares. The result is given in the Figure 5 and shows that the urbanization changed. From the map on the right of the Figure 5, we deduce that the original image has a large part of it which is containing local oscillations of the grey tones, oscillations which correspond to the presence of houses and streets. The areas in the map which are black correspond, in the original images, to the fields of the rural land.

In the Figure 6 we see another example. In the images we have Witney, town on the River Windrush in Oxfordshire, as it was in 1945 and in 2004. In the lower panels we have the maps of squares.

Figure 6. The same as in the Figures 4 and5, in the case of Witney.

Texture transition

Let us consider a sequence of images recorded in 2004 of Carterton and its rural area (Figure 7). We are moving eastwards on Google Earth. We can easily observe in them a "texture transition", that is a transition from the "rural" texture to the "urban" texture. In the Figure 7 we are giving just three images to represent a sequence that can be very long, containing several images.

In 7.a we have a map characterized by black squares; in 7.c we have a large number of bright pixels. And 7.b is between them. We can tell that we have a texture transition, because 7.a has a texture different from 7.c (for the texture transitions of the liquid crystals, see please [START_REF] Haralick | Statistical and structural approach to textures[END_REF][START_REF] Montrucchio | A new image processing method for enhancing the detection sensitivity of smooth transitions in liquid crystals[END_REF][START_REF] Sparavigna | Texture transitions in the liquid crystalline alkyloxybenzoic acid 6OBAC[END_REF]). The textures are different because they have different histograms of their colour tones (the histograms are given in the Figure 8). The rural texture is characterized by a peak near low values of color tones, whereas the urban texture has two peaks, one is larger and broad corresponding to higher values of color tone. The texture transition is therefore a transition from an unimodal histogram to a bimodal histogram.

Conclusion

The aim of the paper is that of evidencing the processes of urbanization from the Google Earth time series of images. The method is a statistical method based on mean values and standard deviations, calculated from the pixels of satellite or aerial images. Using these quantities, a map is obtained, from which it is possible to distinguish urban from rural areas. The method can be applied to other processes that we can observed in satellite images.

,..

  where c corresponds to the three channels R, G, B. The integer indeces i and j are ranging in the x and y direction of the cartesian frame, corresponding to the image frame. Let us fix an integer P ; we subdivide the image in squares having size P P × , or, more specifically The upper left corrner of each square is a pixel of the image that we indicate as ) We compute the local average brightness as: Then, we evaluate the ratio:

(

Figure 1 :

 1 Figure 1: Urban area and agricultural land (Courtesy Google Earth).

Figure 4 :

 4 Figure 4: In the left panel we have Carterton in an aerial image of 1945, and, in the right panel, the town in a satellite image of 2004 (Courtesy Google Earth).

Figure 7 :

 7 Figure 7: Sequence of images of 2004; from left to right, 7.a, 7.b, and 7.c.

Figure 8 .

 8 Figure 8. Histograms of the maps.