Sunday, April 12, 2009

Allegorie ed effetti del Buono e Cattivo Governo

Le due Allegorie ed effetti del Buono e Cattivo Governo, dispiegati su tre pareti opposte per una lunghezza complessiva di circa quattordici metri ciascuno, più i sette metri e settanta dell' Allegoria del Buon Governo sul lato breve della sala. Fu uno dei primi messaggi di propaganda politica in un'opera medievale.

Nell'Allegoria del Buon Governo la Giustizia è assisa in trono sulla sinistra, con una grande bilancia, sui cui bracci due angeli amministrano premi e punizione: per esempio quello di sinistra con una mano decapita un uomo, con l'altra ne incorona un altro. La Giustizia guarda in alto, dove vola la Sapienza, che la istruisce. Sotto la Giustizia sta seduta a un banco la Concordia, diretta conseguenza della prima, che dà ai cittadini le corde per muovere i piatti della bilancia della giustizia. Il corteo di cittadini va quindi verso il simbolo di Siena, la lupa con i due gemelli, sopra il quale si emana il Buon Governo, rappresentato da un monarca in maestà. A lui i cittadini offrono la corda per manovrare la Giustiza. Il Buon Governo è protetto dalle tre Virtù teologali (Fede, Speranza e Carità), mentre ai lati del trono, su un sedile coperto da splendide stoffe, sono assise in varie pose le personificazioni della Giustizia, della Temperanza, della Magnanimità, della Prudenza, della Fortezza e della Pace. Famosa è la figura della pace, mollemente semisdraiata in una posa sinuosa, con un rametto di ulivo in mano. Nell'angolo destro il pittore sistemò, con un disegno acutamente realistico, una serie di prigionieri scortati da guardie a cavallo. Essi rimangono fuori dalle mura che si ergono a fianco della lupa.









Diretta emanazione dell'allegoria è l'affresco degli Effetti del buon governo in città e in campagna sulla parete successiva, che doveva rappresentare con un esempio eloquente gli obiettivi dei governanti della città.

A sinistra un città magnificamente dipinta (la stessa Siena, come dimostra il campanile e la cupola del Duomo che spuntano nell'angolo in alto a sinistra) è popolata da abitanti laboriosi, ben edificata e gaia, come sottolinea l'elegante girotondo di fanciulle.









A destra si dispiega la campagna, dove merci e persone viaggiano in sicurezza, la terra fertile viene coltivata, i giovani vanno a caccia, mentre in aria vola la personificazione della Sicurezza, che regge un delinquente impiccato









e un cartiglio:

"Senza paura ogn'uom franco camini
e lavorando semini ciascuno
mentre che tal comuno
manterrà questa donna in signoria
ch'el alevata arei ogni balia"



L'affresco dell' Allegoria ed effetti del cattivo Governo è più danneggiato, con diverse zone interessate dalla caduta della superficie pittorica. Dipinto in maniera speculare a quello del Buon Governo, doveva permettere il diretto confronto didascalico con l'affresco sulla parete opposta. Un diavolo simboleggia la Tirannide, sul quale volano Avarizia, Sperbia e Vanagloria; della sua bestiale corte fanno parte Furore, Divisione, Guerra, Frode, Tradimento e Crudeltà. Ai suoi piedi la Giustizia legata è tenuta da un individuo solo (non dalla comunità). La città del Cattivo Governo è crollante e piena di macerie, perché i suoi cittadini distruggono piuttosto che costruire, vi si svolgono omicidi, innocenti vengono arrestati, le attività economiche sono miserabili. La campagna è incendiata ed eserciti marciano verso le mura. In cielo vola il sinistro Timore.

Nel dipingere le scene Ambrogio ricorse a stratagemmi fini, per esempio nel Buon Governo la prospettiva e la luce sono costruite in modo da mostrare serenamente la città fino in profondità, mentre la scura città del Cattivo Governo dà subito una sensazione di disarmonia, con tetri edifici che bloccano la visuale.

Nell'affresco venne rappresentato il paesaggio rurale ed urbano, quasi assoluta novità nel panorama artistico dell'epoca (presente già in alcune miniature di ambito federiciano, ma molto più stilizzato), con una cura del dettaglio, una vastezza ed una credibilità mai toccate finora. Tuttavia questa rappresentazione non era fine a se stessa (volontà di portare una testimonianza di un paesaggio) ma fa parte di un preciso messaggio politico, veicolato dal paesaggio: la campagna qui illustra allegoricamente un concetto (di effetto di un regime politico), non "un" paesaggio.

Ambrogio Lorenzetti
Palazzo Comunale di Siena

Allegorie ed effetti del Buono e Cattivo Governo

Le due Allegorie ed effetti del Buono e Cattivo Governo, dispiegati su tre pareti opposte per una lunghezza complessiva di circa quattordici metri ciascuno, più i sette metri e settanta dell' Allegoria del Buon Governo sul lato breve della sala. Fu uno dei primi messaggi di propaganda politica in un'opera medievale.

Nell'Allegoria del Buon Governo la Giustizia è assisa in trono sulla sinistra, con una grande bilancia, sui cui bracci due angeli amministrano premi e punizione: per esempio quello di sinistra con una mano decapita un uomo, con l'altra ne incorona un altro. La Giustizia guarda in alto, dove vola la Sapienza, che la istruisce. Sotto la Giustizia sta seduta a un banco la Concordia, diretta conseguenza della prima, che dà ai cittadini le corde per muovere i piatti della bilancia della giustizia. Il corteo di cittadini va quindi verso il simbolo di Siena, la lupa con i due gemelli, sopra il quale si emana il Buon Governo, rappresentato da un monarca in maestà. A lui i cittadini offrono la corda per manovrare la Giustiza. Il Buon Governo è protetto dalle tre Virtù teologali (Fede, Speranza e Carità), mentre ai lati del trono, su un sedile coperto da splendide stoffe, sono assise in varie pose le personificazioni della Giustizia, della Temperanza, della Magnanimità, della Prudenza, della Fortezza e della Pace. Famosa è la figura della pace, mollemente semisdraiata in una posa sinuosa, con un rametto di ulivo in mano. Nell'angolo destro il pittore sistemò, con un disegno acutamente realistico, una serie di prigionieri scortati da guardie a cavallo. Essi rimangono fuori dalle mura che si ergono a fianco della lupa.





Diretta emanazione dell'allegoria è l'affresco degli Effetti del buon governo in città e in campagna sulla parete successiva, che doveva rappresentare con un esempio eloquente gli obiettivi dei governanti della città. A sinistra un città magnificamente dipinta (la stessa Siena, come dimostra il campanile e la cupola del Duomo che spuntano nell'angolo in alto a sinistra) è popolata da abitanti laboriosi, ben edificata e gaia, come sottolinea l'elegante girotondo di fanciulle. A destra si dispiega la campagna, dove merci e persone viaggiano in sicurezza, la terra fertile viene coltivata, i giovani vanno a caccia, mentre in aria vola la personificazione della Sicurezza, che regge un delinquente impiccato e un cartiglio:


« Senza paura ogn'uom franco camini

e lavorando semini ciascuno
mentre che tal comuno
manterrà questa donna in signoria

ch'el alevata arei ogni balia »



















Nel dipingere le scene Ambrogio ricorse a stratagemmi fini, per esempio nel Buon Governo la prospettiva e la luce sono costruite in modo da mostrare serenamente la città fino in profondità, mentre la scura città del Cattivo Governo dà subito una sensazione di disarmonia, con tetri edifici che bloccano la visuale.

Nell'affresco venne rappresentato il paesaggio rurale ed urbano, quasi assoluta novità nel panorama artistico dell'epoca (presente già in alcune miniature di ambito federiciano, ma molto più stilizzato), con una cura del dettaglio, una vastezza ed una credibilità mai toccate finora. Tuttavia questa rappresentazione non era fine a se stessa (volontà di portare una testimonianza di un paesaggio) ma fa parte di un preciso messaggio politico, veicolato dal paesaggio: la campagna qui illustra allegoricamente un concetto (di effetto di un regime politico), non "un" paesaggio.

Influenzato dalla prima formazione avvenuta a Siena, Ambrogio tuttavia si discostò dai caratteri dominanti di tale arte tanto che è difficile ritenerlo un'esponente tipico della pittura senese del Trecento.

Entrambi i fratelli probabilmente morirono durante la prima grande ondata di peste nera che nel 1348 decimò in maniera terribile le popolazioni dell'Europa occidentale.

Opere di Ambrogio Lorenzetti. Siena, Palazzo Comunale.

Thursday, April 09, 2009

Sexe contre nourriture : les chimpanzés femelles se donnent aux plus généreux


Selon une étude allemande rendue publique mercredi 8 avril, les chimpanzés mâles ont tout intérêt à "acheter" les faveurs de leur compagne avec un peu de nourriture : les femelles se montreraient en effet plus enclines à s'accoupler si on leur offre de la viande.

Après avoir observé pendant près de deux ans un groupe de chimpanzés dans le parc national de Taï en Côte d'Ivoire, les auteurs de cette étude, témoins de 262 accouplements sur cette période, sont arrivés à la conclusion que "les chimpanzés sauvages femelles copulent plus fréquemment avec les mâles qui (...) partagent leur viande avec elles". "Ces résultats suggèrent que les chimpanzés sauvages échangent de la viande contre du sexe, et cela sur une longue période", a expliqué Cristina Gomes, primatologuee à l'Institut Max-Planck d'anthropologie évolutive de Leipzig.

DE LA ZOOLOGIE À L'ANTHROPOLOGIE

Les scientifiques avaient remarqué depuis longtemps que ces singes grégaires partageaient fréquemment le produit de leur chasse, même avec des femelles n'y ayant pas participé, mais ils ne comprenaient pas pourquoi. Or cette nouvelle étude montre que "les mâles qui partagent leurs proies doublent leurs chances de s'accoupler", selon Mme Gomes. L'autre auteur de l'étude, le biologiste franco-suisse Christophe Boesch, a affirmé que ce travail "aurait une influence sur nos connaissances actuelles des relations entre les hommes et les femmes".

La problématique "sexe contre nourriture" pourrait ainsi passer du champ de la zoologie à celui de l'anthropologie : les scientifiques ont établi depuis longtemps que, dans les sociétés primitives de chasseurs-cueilleurs, les chasseurs performants ont davantage d'épouses et donc d'enfants, sans que ce lien ait été explicité jusqu'à présent.

LEMONDE.FR avec AFP | 08.04.09 | 21h00

Friday, March 20, 2009

Lascaux, grotte en péril : on est en limite de méthode, confronté au maximum de nos savoir-faire.


"Sauver la face ou sauver Lascaux". En clair, "cessez de dire que tout va bien à Lascaux. Depuis l'an 2000, l'administration a fait la politique de l'autruche et du déni public".

L'enjeu est de taille, il s'agit de la préservation d'un trésor de l'humanité, l'ensemble des grottes ornées de la vallée de la Vézère, en Dordogne. Leur décor pariétal impressionna tant Georges Bataille, que l'écrivain en parlait, en 1955, comme de la "naissance de l'art". Selon le préhistorien Jean Clottes, qui a présidé le symposium international "Lascaux et la conservation en milieu souterrain", organisé à l'initiative de la ministre de la culture Christine Albanel, les jeudi 26 et vendredi 27 février à Paris, "un ou plusieurs grands artistes, des Michel-Ange, auraient travaillé il y a 17 000 ans, voire 20 000 ans, dans cette grotte spectaculaire". "C'est plein de vie, dit-il, les animaux, aurochs (boeufs sauvages), chevaux, cerfs sautent, bondissent, tombent à la renverse, se croisent, traversent une rivière, la tête haute."

Le rapport de l'ICPL pointe l'altération du décor pariétal aux prises avec une prolifération de bactéries sur les parois de la grotte, qui s'aggrave faute d'une méthode scientifique rigoureuse. Une situation nourrie par la "rivalité sourde entre l'administration des monuments historiques et les archéologues qui se disputent la gestion de ce joyau" (Le Monde, du 27 novembre 2007). Le cri d'alarme de Mme Leauté-Beasley a enclenché un compte à rebours. La France est sommée par l'Unesco de redresser la barre d'ici à l'été prochain, sous peine de voir inscrit Lascaux sur la liste du Patrimoine mondial en péril "en l'absence de progrès substantiels dans l'identification des causes et du traitement des peintures".

Il était temps de briser l'omerta sur la réalité des risques encourus par le site. "Depuis neuf ans, on patauge", se désole Pierre Vidal, ingénieur au CNRS, spécialiste de l'art rupestre, qui a assuré, de 1957 à 1996, le suivi scientifique de la grotte. A 73 ans, celui qui se dit "la mémoire de Lascaux", regrette "les interventions au jour le jour, sans actions coordonnées, et parle de bricolage. L'équilibre climatique a été rompu, on a oublié tous les protocoles, on s'est coupé de tout ce qui a été fait jusqu'en 2000. Pendant trente ans, la grotte n'avait pas bougé".

Que s'est-il passé ? Il semble que le manque de précautions sanitaires, en 1999 et 2000, durant les travaux liés à l'installation de la nouvelle machine de conditionnement d'air, et que le bouleversement climatique engendré par ladite machine "trop puissante et mal adaptée" aient provoqué une "détérioration dramatique de l'équilibre biologique de la grotte", précise Paul-Marie Guyon, physicien à la retraite, qui avait mis au point la précédente machine, "une petite assistance climatique" qui avait fait ses preuves.

D'où l'invasion d'une colonie de champignons blancs déclenchée en 2000. Le traitement radical appliqué, avec de la chaux déversée sur le sol, n'aurait pas été sans conséquences sur cet organisme vivant ultra-fragile qu'est une grotte. Comme l'éclairage intensif des parois pour la réalisation d'un état des lieux en 3D. Des centaines d'heures de projecteurs braqués sur les parois, sans se conformer au contrôle sévère de la lumière. Lequel, selon le cahier des charges, était limité à trente-cinq minutes par jour, cinq jours par semaine, depuis la réouverture de la grotte au public en 1976 - la grotte fut fermée par Malraux en 1963 suite à l'apparition d'algues vertes : elle accueillait jusqu'à 1 800 visiteurs par jour. Dès 2004, apparurent des taches noires sur les parois, de la mélanine provoquée par la lumière et dont on ne parvient pas à arrêter la progression, malgré les traitements successifs.

Lors d'un compte rendu, en avril 2008, Marc Gauthier, président du comité scientifique de la grotte de Lascaux, mis en place en 2002, déclarait pourtant : "La malade est en convalescence, elle est presque guérie." A cette occasion, était dévoilé le Targol Oxyt, un Dévor'Mousse en formule concentrée, sorte de produit miracle censé venir à bout des taches noires. "On ne traite pas Lascaux comme un carré de salades", s'offusque Jean-Philippe Rigaud, conservateur de la grotte de 1977 à 1992. Lequel espère que le colloque organisé les 26 et 27 février remette les scientifiques sur le devant de la scène.

"On est à la huitième année de la crise, la grotte ne fonctionne plus comme par le passé du fait d'un réchauffement du sol, indique, Jean-Michel Geneste, chargé du suivi et de la coordination scientifique de Lascaux. Je reconnais que je n'aurai pas dû accepter la machine livrée, non conforme à la commande. Les travaux ont été le facteur déclenchant. Trop longs. Dans l'urgence, on a essayé de faire au mieux. On est en limite de méthode, confronté au maximum de nos savoir-faire. De même, qu'on ne s'est pas rendu compte que la grotte avait changé de régime climatique."

A l'ouverture du symposium, Christine Albanel, qui veut la transparence, a annoncé la création d'un nouveau comité scientifique pluridisciplinaire, ouvert aux sciences dures, et autonome face à l'administration. "Il faut confronter les propositions, les perspectives. Des erreurs ont sans doute été commises à cause de la complexité du site", dit-on au ministère de la culture. De son côté, Michel Goldberg, biochimiste, ancien directeur scientifique de l'Institut Pasteur a pris l'initiative de réunir au sein d'un comité de réflexion, le Lascaux International Scientific Think Tank (LIST), les meilleurs spécialistes en microbiologie, chimie, hydrogéologie, climatologie, biotechnologie..., jusqu'à Antoine Danchin, expert en génomique bactérienne. Sauver Lascaux est l'affaire de tous. Le temps presse.

Sunday, February 22, 2009

Friday, December 19, 2008

Sunday, November 30, 2008

Monday, November 03, 2008

Raisonnement hypothétique et temps multiforme discret dans les systèmes de production: étude et implémentation

Hypothetical reasoning and multiform discrete time in production systems: study and implementation

Résumé / Abstract

La caractérisation incomplète que l'on n'a du monde externe dans les systèmes experts temps réel nécessite un raisonnement de type révocable, des déductions antérieures pouvant être remises en cause pour rester cohérent avec les nouvelles informations. Le système déductif doit alors être doté d'un système de maintien de la cohérence. A l'opposé des approches existantes qui voient ces deux systèmes dissociés, nous avons choisi d'étendre le langage des règles d'un système de production de type OPS en y intégrant un maintien de la cohérence de type ATMS. Cette approche «langage» nous a permis d'introduire des variables d'environnement, ceux-ci devenant alors manipulables explicitement depuis les règles à l'aide d'un jeu de primitives qui leur est dédié. Cette extension du pouvoir d'expression, outre les contradictions, a enrichi la structure de contrôle en permettant le recours à l'indirection et en ouvrant la voie à la focalisation dans certains mondes. Une négation explicite, ne reposant pas sur l'hypothèse du monde clos, a été introduite et avec laquelle les informations négatives ont le même statut que les informations positives. Nous avons illustré les capacités du langage par un certain nombre d'exemples d'école. Du point de vue de l'implémentation, nous avons introduit une structure d'encodage booléen des environnements qui permet d'exprimer la dépendance entre hypothèses et pour lequel une preuve de décomposition unique a été établie. Enfin nous avons continué dans la démarche suivie pour l'implémentation de l'algorithme de pattern matching duquel on était parti, c'est-à-dire une procéduralisation totale qui conduit à une véritable compilation des règles. Un autre thème a été abordé dans la thèse et concerne plus spécifiquement le temps réel. Il s'agit d'introduire le temps multiforme discret de la programmation synchrone dans les systèmes de production. Toujours dans une approche langage, nous proposons une extension d'un système de production de type OPS permettant la synchronisation des déductions avec des horloges. Ces horloges sont n'importe quel fait de l'application pour laquelle il représente une unité de temps. L'implémentation est détaillée et le coureur d'Esterel vient illustrer cette nouvelle fonctionnalité

Monday, October 20, 2008

Soffrir


Étymologie

Du latin classique sufferre : "supporter, endurer", ou "se soutenir, se maintenir".

Ancienne langue

  • Comme son étymon, ce verbe peut signifier en ancien français "supporter, endurer avec fermeté (ce qui est pénible moralement ou physiquement)". En construction pronominale, se souffrir de signifie "se passer de", et se souffrir signifie "patienter".
  • Il peut aussi avoir le sens de "subir une chose douloureuse, désagréable", d'où le sens de l'expression souffrir quelqu'un, "tolérer sa présence".
  • En contexte militaire, ce verbe peut aussi avoir le sens plus concret de "soutenir (une bataille)", d'où l'expression souffrir quelqu'un, "résister à quelqu'un dans un combat".
  • Ce verbe est aussi employé dans diverses expressions :
    • souffrir le droit : "se laisse juger" ;
    • souffrir + proposition infinitive : "permettre que" ;
    • souffrir quelque chose à quelqu'un : "accorder quelque chose à quelqu'un".

Wednesday, October 15, 2008

Internet use 'good for the brain'

For middle aged and older people at least, using the internet helps boost brain power, research suggests.

http://news.bbc.co.uk/2/hi/health/7667610.stm

A University of California Los Angeles team found searching the web stimulates centres in the brain that control decision-making and complex reasoning.

The researchers say this might even help to counter-act the age-related physiological changes that cause the brain to slow down.

The study features in the American Journal of Geriatric Psychiatry.

A simple, everyday task like searching the web appears to enhance brain circuitry in older adults
Professor Gary Small
University of California Los Angeles

As the brain ages, a number of changes occur, including shrinkage and reductions in cell activity, which can impact on performance.

It has long been thought that activities which keep the brain active, such as crossword puzzles, may help minimise the impact - and the latest study suggests that surfing the web can be added to the list.

Brain activity in an experienced internet user when searching the web
Web use stimulates much more activity in the same brain

Lead researcher Professor Gary Small said: "The study results are encouraging, that emerging computerized technologies may have physiological effects and potential benefits for middle-aged and older adults.

"Internet searching engages complicated brain activity, which may help exercise and improve brain function."

The latest study was based on 24 volunteers aged between 55 and 76. Half were experienced internet users, the rest were not.

Compared with reading

Each volunteer underwent a brain scan while performing web searches and book-reading tasks.

Both types of task produced evidence of significant activity in regions of the brain controlling language, reading, memory and visual abilities.

However, the web search task produced significant additional activity in separate areas of the brain which control decision-making and complex reasoning - but only in those who were experienced web users.

Brain activity in a personal not used to using the web while reading
Brain activity in web newcomers: similar for reading and internet use

The researchers said that compared with simple reading, the internet's wealth of choices requires that people make decisions about what to click on in order to get the relevant information.

However, they suggested that newcomers to the web had not quite grasped the strategies needed to successfully carry out a web search.

Professor Smith said: "A simple, everyday task like searching the web appears to enhance brain circuitry in older adults, demonstrating that our brains are sensitive and can continue to learn as we grow older."

Rebecca Wood, chief executive of the Alzheimer’s Research Trust, said: "These fascinating findings add to previous research suggesting that middle-aged and older people can reduce their risk of dementia by taking part in regular mentally stimulating activities.

"Older web users - 'silver surfers' - are doing precisely this.

"Frequent social interactions, regular exercise and maintaining a balanced diet can also reduce dementia risk."

Dr Susanne Sorensen, head of research at the Alzheimer's Society, said: "Use it or lose it may well be a positive message to keep people active but there is very little real evidence that keeping the brain exercised with puzzles, games or other activities can promote cognitive health and reduce the risk of dementia."

Tuesday, September 23, 2008

Dig pinpoints Stonehenge origins

By James Morgan
Science reporter, BBC News

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The excavation is documented in a BBC Timewatch special

Archaeologists have pinpointed the construction of Stonehenge to 2300BC - a key step to discovering how and why the mysterious edifice was built.

The radiocarbon date is said to be the most accurate yet and means the ring's original bluestones were put up 300 years later than previously thought.

The dating is the major finding from an excavation inside the henge by Profs Tim Darvill and Geoff Wainwright.

The duo found evidence suggesting Stonehenge was a centre of healing.

Others have argued that the monument was a shrine to worship ancestors, or a calendar to mark the solstices.

A documentary following the progress of the recent dig has been recorded by the BBC Timewatch series. It will be broadcast on Saturday 27 September.

Date demand

For centuries, archaeologists have marvelled at the construction of Stonehenge, which lies on Salisbury Plain, Wiltshire.

Mineral analysis indicates that the original circle of bluestones was transported to the plain from a site 240km (150 miles) away, in the Preseli hills, South Wales.

This extraordinary feat suggests the stones were thought to harbour great powers.

Professors Darvill and Wainwright believe that Stonehenge was a centre of healing - a "Neolithic Lourdes", to which the sick and injured travelled from far and wide, to be healed by the powers of the bluestones.

They note that "an abnormal number" of the corpses found in tombs nearby Stonehenge display signs of serious physical injury and disease.

And analysis of teeth recovered from graves show that "around half" of the corpses were from people who were "not native to the Stonehenge area".

"Stonehenge would attract not only people who were unwell, but people who were capable of [healing] them," said Professor Darvill, of Bournemouth University.

"Therefore, in a sense, Stonehenge becomes 'the A & E' of southern England."

Modern techniques

But without a reliable carbon date for the construction of Stonehenge, it has been difficult to establish this, or any other, theory.

Until now, the consensus view for the date of the first stone circle was anywhere between 2600BC and 2400BC.

To cement the date once and for all, Professors Darvill and Wainwright were granted permission by English Heritage to excavate a patch of earth just 2.5m x 3.5m, in between the two circles of giant sarsen stones.

The dig unearthed about 100 pieces of organic material from the original bluestone sockets, now buried under the monument. Of these, 14 were selected to be sent for modern carbon dating, at Oxford University.

The result - 2300BC - is the most reliable date yet for the erection of the first bluestones.

Strictly speaking, the result was rounded down to "between 2400BC and 2200BC" - but 2300BC is taken as the average.

An even more precise date will be produced in the coming months.

"It's an incredible feeling, a dream come true," said Professor Wainwright, formerly chief archaeologist at English Heritage.

"We told the world we were going to date Stonehenge. That was a risk, but I was always confident," said Professor Darvill.

Please turn on JavaScript. Media requires JavaScript to play.

The archaeologists reveal the first accurate carbon date for Stonehenge

Intriguingly, the date range ties in closely with the date for the burial of the so-called "Amesbury Archer", whose tomb was discovered three miles from Stonehenge.

Some archaeologists believe the Archer is the key to understanding why Stonehenge was built.

Analyses of his corpse and artefacts from his grave indicate he was a wealthy and powerful man, with knowledge of metal working, who had travelled to Salisbury from Alpine Europe, for reasons unknown.

Post mortem examinations show that he suffered from both a serious knee injury and a potentially fatal dental problem, leading Darvill and Wainwright to conclude that the Archer came to Stonehenge to be healed.

But without an accurate date for Stonehenge, it was not even clear whether the temple existed while the Archer was alive.

His remains have been dated between 2500BC and 2300BC - within the same period that the first stone circle was erected.

"It's quite extraordinary that the date of the Amesbury Archer is identical with our new date for the bluestones of Stonehenge," said Professor Darvill.

"These two things happening within living memory of each other for sure is something very, very important."

Earliest occupation

Professor Wainwright added: "Was the Amesbury Archer, as some have suggested, the person responsible for the building of Stonehenge? I think the answer to that is almost certainly 'no'.

"But did he travel there to be healed? Did he limp, or was he carried, all the way from Switzerland to Wiltshire, because he had heard of the miraculous healing properties of Stonehenge? 'Yes, absolutely'.

"Tim and I are quite convinced that people went to Stonehenge to get well. But Stonehenge probably had more than one purpose, so I have no problem with other people's interpretations."

Among other key finds, the team uncovered organic material that indicates people inhabited the Stonehenge site as long ago as 7200BC - more than 3,500 years earlier than anything previously known.

They also found that bluestone chippings outnumbered sarsen stone chippings by three to one - which Wainwright takes to be a sign of their value.

"It could be that people were flaking off pieces of bluestone, in order to create little bits to take away... as lucky amulets," he said.

The duo are preparing to publish an academic report of their excavation, and will announce their findings to their peers next month, in a lecture at London's Society of Antiquaries.

Ongoing debate

Experts on Stonehenge said the new date was a major milestone in understanding Britain's most famous monument.

Dr Andrew Fitzpatrick, of Wessex Archaeology, said: "This is a great result - a very important one.

"The date of Stonehenge had been blowing in the wind. But this anchors it. It helps us to be secure about the chronology of events.

"The theory that it was a centre of healing is certainly a plausible one, but I don't think we can rule out the other main competing theory - that the temple was a meeting point between the land of the living and the dead.

"I am not yet persuaded that the Amesbury Archer came to Stonehenge to be healed. I favour the interpretation that he was one of the earliest metal workers, who travelled to the area to make a living from his skills.

"In any case, it is still not clear if his burial predated Stonehenge."

Dave Batchelor, Stonehenge curator at English Heritage, said: "We are pleased that the professors' precision in targeting that small area of turf and their rigorous standards in archaeological excavations have produced such a rich collection of physical evidence.

"We are looking forward to seeing the results of the full analysis, but from what we understand so far, we believe they have added valuable information to the chronology of Stonehenge."

The BBC Timewatch special is broadcast on BBC Two at 2005 BST on Saturday 27 September

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/7625145.stm

Published: 2008/09/21 23:01:34 GMT

© BBC MMVIII

Saturday, August 23, 2008

Black hole star mystery 'solved'

Astronomers have shed light on how stars can form around a massive black hole, defying conventional wisdom.

http://news.bbc.co.uk/2/hi/science/nature/7574255.stm




Scientists have long puzzled over how stars develop in so extreme conditions.

Molecular clouds - the normal birth places of stars - would be ripped apart by the immense gravity, a team explains in Science magazine.

But the researchers say that stars can form from elliptical discs - the relics of giant gas clouds torn apart by encounters with black holes.

They made the discovery after developing computer simulations of giant gas clouds being sucked into black holes like water spiralling down a plughole.

"These simulations show that young stars can form in the neighbourhood of supermassive black holes as long as there is a reasonable supply of massive clouds of gas from further out in the galaxy," said co-author Ian Bonnell from St Andrews University, UK.

Ripped apart

Their findings are in accordance with actual observations in our Milky Way galaxy that indicate the presence of a massive black hole, surrounded by huge stars with eccentric orbits.

The simulations, performed on a supercomputer - and taking over a year of computing time - followed the evolution of two separate giant gas clouds up to 100,000 times the mass of the Sun, as they fell towards the supermassive black hole.

The simulations show how the clouds are pulled apart by the immense gravitational pull of the black hole.

The disrupted clouds form into spiral patterns as they orbit the black hole; the spiral patterns remove motion energy from gas that passes close to the black hole and transfers it to gas that passes further out.

This allows part of the cloud to be captured by the black hole while the rest escapes.

In these conditions, only high mass stars are able to form and these stars inherit the eccentric orbits from the elliptical disc.

These results match the two primary properties of the young stars in the centre of our galaxy: their high mass and their eccentric orbits around the supermassive black hole.

"That the stars currently present around the galaxy's supermassive black hole have relatively short lifetimes of [about] 10 million years, which suggests that this process is likely to be repetitive," Professor Bonnell explained.

"Such a steady supply of stars into the vicinity of the black hole, and a diet of gas directly accreted by the black hole, may help us understand the origin of supermassive black holes in our and other galaxies in the Universe."

Friday, August 22, 2008

Thursday, August 07, 2008

What is collective intelligence and what will we do about it? Thomas W. Malone, Director MIT Center for Collective Intelligence

Edited transcript of remarks at the official launch of the
MIT Center for Collective Intelligence
October 13, 2006

It now falls to me, at this point in the program, to give you an overview of what collective intelligence is, in the first place, and what we’d like to do about it. The working definition of collective intelligence that we’re using is that collective intelligence is groups of individuals doing things collectively that seem intelligent [Q.: mais comment se reconnaissent-ils?].

Now, if you think about it that way, collective intelligence has existed for a very long time. Families, companies, and countries are all groups of individual people doing things that at least sometimes seem intelligent. Beehives and ant colonies are examples of groups of insects doing things like finding food sources that seem intelligent. And we could even view a single human brain as a collection of individual neurons or parts of the brain that collectively act intelligently.

But in the last few years we’ve seen some very interesting examples of new kinds of collective intelligence:

  • Google, for instance, takes the collective knowledge created by millions of people making websites for other purposes and harnesses that collective knowledge--using some very clever algorithms and sophisticated technology--to produce amazingly intelligent answers to the questions we type in.
  • Wikipidia, at another extreme, uses much less sophisticated technology but some very clever organizational principles and motivational techniques to get thousands of people all over the world to volunteer their time to create an amazing on-line collection of knowledge.
  • In just a few minutes, you’ll hear from Alph Bigham the CEO of a company called Innocentive [est-ce vraiement innocent ?] which lets companies with difficult research problems harness the collective intelligence of thousands of scientists in a network all over the world to help solve those problems.
  • A lot of companies today--Hewlett Packard, Eli Lilly, Google and others--are now beginning to use things called prediction markets [mais qui paie quoi à qui et comment ?] where people buy and sell predictions about future events (like sales of their products) in ways that leads to more accurate predictions in many cases than traditional market research or polling or other techniques.

Now, I think these examples are just the beginning. With new information technologies—especially the Internet—it is now possible to harness the intelligence of huge numbers of people, connected in very different ways and on a much larger scale than has ever been possible before. In order to take advantage of these possibilities, however, we need to understand what the possibilities are in a much deeper way than we do so far.

So, I think the time has come make collective intelligence a topic of serious academic study. And that is our goal in the Center for Collective Intelligence.

The key question we’re using to organize our work is: How can people and computers be connected so that collectively they act more intelligently than any individual, group, or computer has ever done before?

In order to answer that question, I think at least three types of research are needed. The first is just collecting examples or case studies [Malone : mais tu ne change jamais de méthode ?]. I think there are going to be a lot of natural experiments going on in the next few years, people trying lots of interesting things--with or without us. But I think that we can help the world learn from its experience with all these natural experiments by systematically describing and collecting examples of interesting cases of collective intelligence.

For instance, Eric von Hippel, in the Sloan School, has done some very interesting case studies of how the collective body of users of a product is often a better source of innovation for a company’s products than the company’s own researchers [Ndr : y-avait-t-il vraiement besoin de faire une étude ???]. This kind of case study research is common in business schools, but it is certainly not the only kind of research we need to do.

Another kind of research we need to do is something that is more typical in an engineering school. That is to create new examples of the phenomena we want to study. If you’re an aeronautical engineer, for instance, you wouldn’t just study birds and flying insects, you’d also want to create some flying machines and study how they work. In our case, that means we want to create some new examples of collective intelligence and study how they work.

For instance, Mark Klein in the Center for Collective Intelligence is leading a group of people in a nascent project that hopes to harness the collective intelligence of thousands of people around the world to help deal with the problems of global climate change [& l'Opus Dei ? Qu'en fait-on ?]. We have some specific technical ideas about how to combine computer simulation techniques with online ways of representing issues and positions and arguments that we think may be helpful in this process.

In the process of creating new examples, we hope to advance the state of the art and to learn new design principles not just for the technologies, by the way [BTW], but also for the human, the organizational, the social, and the motivational systems that are needed for these systems to work effectively.
But case studies and creating new examples are not the only things we need to do. I think we also need to do systematic studies and experiments. For instance, in some cases, we’ll find examples of things that work well but we won’t know why from just a case study. So we need to do systematic experiments to help figure those things out. This is the kind of research that would be more often done in a school of science or a school of social science. For example, Sandy Pentland (in the Media Lab), Drazen Prelec (in the Sloan School), and Josh Tennenbaum (in the Brain and Cognitive Sciences department) are all doing different laboratory experiments about different ways of helping groups make predictions more effectively [c'est joli la diversité !].

But these three things--case studies, new examples, and systematic experiments--are not the only things we need to do. We also need new theories to help tie all these things together [ça devient compliqué ...]. I think that is especially important in the case of collective intelligence because there’s now a lot of hype and prejudice going around about collective intelligence [de qui parle-t-il ?].

On the one hand, there are people who think that collective intelligence is magic, and if you just add it, it’ll make everything wonderful. For instance, there is a book called The Wisdom of Crowds by James Surowiecki who--by the way--does not believe what I just said. But many people who’ve heard about his book do believe it. They think that just doing things “collectively” will make everything great.

On the other hand, there are people who are prejudiced against the very notion of collectiveness and decentralization. Very recently for instance, there have been a number of people who’ve looked at the success of Wikipedia and pointed out ways in which is not perfect. And then, based on that, they have argued that nothing without central control can ever be successful.

Now, I think both of these extremes are equally wrong. Sometimes collective intelligence is good; sometimes it isn’t. Sometimes it works, and sometimes it doesn’t. A very important part of our goal is to help put a more solid scientific foundation under the claims in this area.

Fortunately, we don’t have to start from scratch [scratch] in doing that. There’s already a lot of good work that has been done in many fields, including psychology, organization theory, artificial intelligence, brain science and others. Part of what we want to do is to help organize the work that has already been done.

But even if we had already organized all of the results of all of the previous research, there would still a lot to learn. New technologies are now making it possible to organize groups in very new ways, in ways that have never been possible before in the history of humanity. And no one yet understands how to take advantage of these possibilities.

We certainly don’t have all the answers yet; we’re just beginning to ask the questions [ça c'est prudentiellement bien prudent, bravo!]. We hope we can make a contribution just by helping to frame the questions better [je suis d'accord : le plus important c'est de poser les bonnes questions ... c'est déjà fini la lecture ...]. We’re pretty [pretty] sure we can have a lot of fun trying. And we hope that in the long run the work we do in this center will help contribute to scientific understanding in many different disciplines and help us understand new and better ways to organize businesses, to conduct science, to run governments, and--perhaps most importantly--to help solve the problems we face as society and as a planet.

Sunday, August 03, 2008

L’Albatros


Souvent, pour s’amuser, les hommes d’équipage
Prennent des albatros, vastes oiseaux des mers,
Qui suivent, indolents compagnons de voyage,
Le navire glissant sur les gouffres amers.



À peine les ont-ils déposés sur les planches,
Que ces rois de l’azur, maladroits et honteux,
Laissent piteusement leurs grandes ailes blanches
Comme des avirons traîner à côté d’eux.

Ce voyageur ailé, comme il est gauche et veule !
Lui, naguère si beau, qu’il est comique et laid !
L’un agace son bec avec un brûle-gueule,
L’autre mime, en boitant, l’infirme qui volait !

Le Poète est semblable au prince des nuées
Qui hante la tempête et se rit de l’archer ;
Exilé sur le sol au milieu des huées,
Ses ailes de géant l’empêchent de marcher.

Charles Baudelaire
Les fleurs du mal

Friday, July 18, 2008

L'origine della Luce

La lüs a lè nassìda al tèp dei tèp in cèl, intàt che al Padretèrno a gh'ìa scapàt in fàl la prima ögiàda 'n giro per mètes a creàl ! La lüs a l'ia selvàdega e dispetúsa insèm, la sìa metìda sübet a fà balà la lüna col súl e i stèle 'n cèl compàgn d'ü mülinèl ! L'ìa trasfurmàt ol mònt con töt ol sò calùr in d'öna gran furnàs per inventà i culùr de pitürà zò'l cèl con töt ol sò splendùr !

A gh'è ülìt del tèp perchè la se calmès e la troès la pàs in fì a' de'nnamuràs e de fà crès i fiùr con töcc i sò culùr ! La lüs la s'è cambiàda in cèl come öna fàta che'impìa e smòrza zò ol sul come ü falò, de nöcc, la lüna e i stèle coi dìcc facc a fiamèle ! La lüs lè töta amùr, la te dà èta e fiàt e òia a' de campà, la te fà sèmper fèsta perchè l'è'nnamuràda de töcc ì'nnamuràcc !

La lüs l'è sèmper bèla in cèl e sö la tèra e quando la sberlüs la dìs "sò mè l'amùr che scòlda töcc i nì e che fà crès i fiùr ! " La lüs l'è verità, ghe scàpa gna ü pensèr col bè e col màl che s'fà la ghe fà ciàr a töcc de dèt e fò de cà per chi la öl dovrà ! La lüs l'è sèmper giöstra a'sè la par sbagliàda a chi ghe ulta i spale perchè la ghe fà ombra e i sèra i öcc per vèt apèna chèl che i crèt !

La lüs la fà pensà a Chèl che l'à 'nventàda perchè l'è apèna Lü che l'pöl amò smorsàla isce' come là fàcc ai tèp che l'l'à mpiàda ! Ma quando 'l Creatùr l'ismorserà sta lüs, la sarà prònta l'òtra, piö bèla e amò piö fòrta, chèla che l'à decìs de dàm in paradìs !

don Guilio Gabanelli