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L'antimatière est-elle soumise à uneantigravité? Expériences enpréparation
De Annie HAUTEFEUILLE (AFP) – Il y a 8 heures
PARIS — L'antimatière est-elle soumise à la même gravité que la matière ordinaire ou à une forme inconnue d'antigravité? Des expériences se préparent pour mesurer les propriétés de cette matière "miroir", expliquent des chercheurs français participant au colloque "Antimatière et gravitation", qui se terminait mardi à Paris.
"C'est un vieux rêve de physicien de mesurer l'action de la gravitation sur l'antimatière", résume Gabriel Chardin, du Centre national de la recherche scientifique (CNRS) et de l'université Paris-Sud).
Avec la découverte, en 1998, d'une accélération de la vitesse d'expansion de l'univers, récompensée la semaine dernière par le prix Nobel de physique, l'idée d'une "pression négative" ou sorte de gravité répulsive a gagné du terrain.
Si l'antimatière réagissait différemment de la matière à la gravitation "ce serait une révolution" pour la physique, souligne Patrice Pérez (Institut de recherche sur les lois fondamentales de l'Univers -Irfu/cea).
Matière "miroir" de celle que nous connaissons, l'antimatière reste difficile à observer car tout atome d'antimatière s'annihile au contact de la matière, en produisant une énorme quantité d'énergie.
Un atome d'hydrogène est formé d'un proton ayant une charge électrique positive et d'un électron négatif. Un atome d'antihydrogène est constitué d'un proton négatif (antiproton) et d'un électron positif (positron).
De premiers atomes d'antihydrogène, produits en 1995 au Centre européen de recherches nucléaires (Cern) à Genève, s'étaient annihilés quasi-instantanément au contact de la matière.
D'importants progrès ont été accomplis : des atomes d'antihydrogène ont été piégés pendant plus de 16 minutes au Cern, selon les résultats, publiés en juin dernier, d'une nouvelle expérience qui devrait faciliter l'étude de l'antimatière.
Les physiciens réussissent plus facilement à contrôler, grâce à des champs magnétiques, un antiproton, particule porteuse d'une charge électrique, qu'un atome neutre d'antimatière.
D'où l'idée de recourir à des ions positifs d'antihydrogène (un antiproton négatif associé à deux positrons), relève Patrice Pérez, qui participe au projet international GBAR (Gravitationnal Behaviour of Antihydrogen at Rest - Comportement gravitationnel de l'antihydrogène au repos).
Ces ions, refroidis à 10 microkelvins (10 millionièmes de degré au dessus du zéro absolu : -273,15 °C) pour réduire leur agitation, seraient dépouillés au dernier moment, grâce à un faisceau laser, de leur positron surnuméraire.
Il s'agit ensuite de mesurer la "vitesse de chute" des atomes d'antihydrogène ainsi créés, précise Patrice Pérez qui espère que cette expérience pourra être réalisée au Cern d'ici 2016.
Il serait alors possible de savoir si l'antimatière subit la même accélération due à la pesanteur que la matière.
L'instant où les positrons en trop sont arrachés donnerait, selon M. Pérez, le "top départ" de la chute verticale, et leur désintégration au contact de la matière "le temps d'arrivée".
(BN) Jobs’s Death Leaves Hollywood Without Trusted Technology Envoy
Bloomberg News, envoyé de mon iPhone.
Jobs’s Death Leaves Hollywood Without Trusted Tech Envoy
Oct. 7 (Bloomberg) -- Steve Jobs’s death leaves Hollywood without the trusted technology envoy who helped push the film, TV and music industries into the digital age.
In the 25 years after he bought George Lucas’s digital animation business and renamed it Pixar, Jobs charmed, angered and cajoled Hollywood executives as he pursued his vision for digital entertainment. He clashed with former Walt Disney Co. Chief Executive Officer Michael Eisner over their movie partnership, while befriending Eisner’s successor, Robert Iger.
Apple Inc.’s co-founder relentlessly challenged the industry to change -- ushering in the age of digital animation with “Toy Story,” upending the record labels with the iPod and the iTunes store, and by negotiating to sell TV shows and films online. Disney’s ABC was the first to sign on.
“Steve and I were talking for months about delivering TV shows on iTunes, which is when he shows me the video iPod, and I said, ‘We’re in!’” Iger said in e-mail. “Movies were next, a year later. It was about what we wanted to do and what we felt was right for our business.”
With the 2006 sale of Pixar, Jobs became Burbank, California-based Disney’s biggest investor, with a stake worth $4.35 billion.
Hollywood executives resisted putting shows online. Piracy had devastated the music industry and iTunes’ dominance of online music retailing gave Cupertino, California-based Apple unprecedented influence over the record labels.
‘Getting It’
Jobs was determined to get the studios on board, said Jim Gianopulos, co-chairman of News Corp.’s Fox Filmed Entertainment.
“He’d call up and say, ‘We’ve got to do this, this is the way to do it, and you guys aren’t getting it,’” Gianopulos said in an interview. “We would banter back and forth, but we always found ways to work together. To his great credit, he would see an aspect of the film side, the media side, that he hadn’t considered, and he would call back the next day and he would have figured out how to work that problem.”
Today, iTunes is the top seller of online movies, with 66 percent of the market for electronic sales and Web video-on- demand, researcher IHS said in August. Its share of U.S. music retailing was 70 percent last year, according to NPD.
“Steve understood that the only way to compete with piracy was to create a system that by its very nature is more convenient for consumers,” said Paul Vidich, a Warner Music Group Corp. executive who negotiated the first record-label agreement with Apple.
‘Rocket Ship’
Diagnosed with a rare form of pancreatic cancer in 2003, Jobs died Oct. 5 at age 56. Gianopulos said his discussions with Jobs over film rights evolved into a personal friendship.
“He would come into the meeting and say, ‘Hey, you want to see something cool?’ And he would reach into his jacket and pull out the first prototype of the iPhone,” Gianopulos said. “It was like someone had shown you the first rocket ship.”
Disney, the pioneer in animation and theme parks, became a lab for Jobs. The studio served as distributor of Pixar movies starting in 1995. Later, after Jobs sold the animation studio to Disney for $8.06 billion in stock, the company became an Internet trailblazer as well -- becoming the first of its peers to offer films and TV shows on iTunes.
Today former Pixar CEO Ed Catmull oversees all of Disney’s animation. John Lasseter, Pixar’s creative leader, holds a similar post at Disney with roles in films and theme parks.
Clash With Eisner
Relations with Disney almost foundered in 2003 in a dispute with Eisner over an extension of the Pixar deal, and on Jan. 30, 2004, Jobs announced Pixar was looking elsewhere. In nine years, the partnership had produced some of Disney’s top-grossing pictures, such as “Finding Nemo.”
By that time, Eisner’s position at Disney was shaky. His pay and flagging stock angered institutional investors and Roy Disney, nephew of founder Walt and an influential shareholder. Iger was named to succeed Eisner in March 2005 and the first call was with Jobs.
“He wished me well and hoped we could work together soon,” Iger said in a 2005 interview with Businessweek. In October, within two weeks of taking over, Iger agreed to sell episodes of TV shows from Disney’s ABC network on iTunes for $1.99 each. Three months later, he clinched the deal for Pixar.
Pixar’s 12 movies have generated $5.73 billion in worldwide box office sales for Disney and theater operators, according to Box Office Mojo, a movie-tracking service. They’ve become theme- park attractions and a “Cars” land will open at Disney’s California Adventure next year.
‘Pretty Simple’
The entertainment industry is still grappling with how to prosper in the digital world Jobs helped create.
In August, after a year-long experiment, Apple ended its 99-cent rentals of TV episodes from Fox and ABC. CBS Corp., owner of the most-watched U.S. TV network, and NBC didn’t participate because the price was too low.
After first caving in to Jobs’s demands that all songs sell for 99 cents, the music industry last year won more control over pricing on iTunes, pushing through a 30-cent increase in the price of some tracks.
Music executives credit Jobs with saving the industry from Internet piracy.
“The guy had been doing serious thinking while we were all batting our heads against a wall,” Jimmy Iovine, chairman of Interscope-Geffen-A&M, said in a 2004 interview. “He was going to provide us with that great interface and we were going to give him unique content that you couldn’t get anywhere else. It was pretty simple, really.”
To contact the reporters on this story: Michael White in Los Angeles at mwhite8@bloomberg.net Ronald Grover in Los Angeles at rgrover5@bloomberg.net Andy Fixmer in Los Angeles at afixmer@bloomberg.net
To contact the editor responsible for this story: Anthony Palazzo at apalazzo@bloomberg.net
En savoir plus sur Bloomberg pour iPhone: http://m.bloomberg.com/iphone/Back to the Mamila :-)))
Yerushalaïm im raverim
Bactérie E. Coli : les graines germées pourraient venir d'Egypte
Les graines germées à l'origine des épidémies E. coli qui touchent l'Allemagne et la ville de Bordeaux pourraient provenir d'Egypte. Alors que 48 victimes sont aujourd'hui à déplorer, cette piste tend à confirmer que les deux épidémies sont bien liées.
Les autorités sanitaires tentent toujours de remonter la piste des graines germées contaminées par la souche O154 :H4 de la bactérie E.coli.Une contamination qui a fait à ce jour 48 morts outre-Rhin, et a atteint une quinzaine de personnes en France, où la ville de Bordeaux est actuellement la seule touchée. Cette souche d’E.coli est très rare chez les humains, c'est pourquoi les experts de l'Agence européenne de sécurité sanitaire (EFSA) pensent que les épidémies allemande et française sont liées.
Dans les deux cas, les personnes atteintes de diarrhées sanglantes avaient consommé des graines germées. L'enquête a mené les autorités sanitaires sur la piste de semences de fenugrec, une légumineuse méditerranéenne. Des graines qui auraient été importées d'Egypte en 2009 et en 2010 par la société allemande AGA SAAT, révèle l'EFSA dans un communiqué publié sur son site Internet. Selon le Figaro, ces semences seraient issues de culture biologique et auraient été cultivées par la ferme Gärtnerhof en Basse-Saxe, d'où serait partie l'épidémie allemande. Un autre lot de graines aurait été vendu à la société britannique Thompson & Morgan qui l'aurait elle-même cédé au magasin Jardiland de Villenave-d'Ornon, près de Bordeaux. Or c'est dans ce magasin que des graines ont été achetées avant d'être germées et servies le 8 juin lors d'une kermesse scolaire. Une fête à laquelle onze des seize personnes atteintes par la bactérie avaient participé.
Afin de confirmer cette piste, les experts vont analyser les graines égyptiennes et ainsi déterminer si elles sont porteuses de la souche O154 : H4. En outre, cette même souche a fait une victime isolée en Suède, et pour l'heure aucun lien n'a pu être établi avec les épidémies allemande et française.
Sunset in Caesaria
Quelqu'un connait cette chanson? Shazam ne la reconnait pas ...
(download)
enregistrée sur mon iphone via dictaphone.
A letter from Mason that was included with Groupon’s filing.
Dear Potential Stockholders,
On the day of this writing, Groupon’s over 7,000 employees offered more than 1,000 daily deals to 83 million subscribers across 43 countries and have sold to date over 70 million Groupons. Reaching this scale in about 30 months required a great deal of operating flexibility, dating back to Groupon’s founding.
Before Groupon, there was The Point—a website launched in November 2007 after my former employer and one of my co-founders, Eric Lefkofsky, asked me to leave graduate school so we could start a business. The Point is a social action platform that lets anyone organize a campaign asking others to give money or take action as a group, but only once a “tipping point” of people agree to participate.
I started The Point to empower the little guy and solve the world’s unsolvable problems. A year later, I started Groupon to get Eric to stop bugging me to find a business model. Groupon, which started as a side project in November 2008, applied The Point’s technology to group buying. By January 2009, its popularity soaring, we had fully shifted our attention to Groupon.
I’m writing this letter to provide some insight into how we run Groupon. While we’re looking forward to being a public company, we intend to continue operating according to the long-term focused principles that have gotten us to this point. These include:
We aggressively invest in growth.
We spend a lot of money acquiring new subscribers because we can measure the return and believe in the long-term value of the marketplace we’re creating. In the past, we’ve made investments in growth that turned a healthy forecasted quarterly profit into a sizable loss. When we see opportunities to invest in long-term growth, expect that we will pursue them regardless of certain short-term consequences.
We are always reinventing ourselves.
In our early days, each Groupon market featured only one deal per day. The model was built around our limitations: We had a tiny community of customers and merchants.
As we grew, we ran into the opposite problem. Overwhelming demand from merchants, with nine-month waiting lists in some markets, left merchant demand unfilled and contributed to hundreds of Groupon clones springing up around the world. And our customer base grew so large that many of our merchants had an entirely new problem: Struggling with too many customers instead of too few.
To adapt, we increased our investment in technology and released deal targeting, enabling us to feature different deals for different subscribers in the same market based on their personal preferences. In addition to providing a more relevant customer experience, this helped us to manage the flow of customers and opened the Groupon marketplace to more merchants, in turn diminishing a reason for clones to exist.
Today, we are pursuing models of reinvention that would not be possible without the critical mass of customers and merchants we have achieved. Groupon NOW, for example, allows customers to pull deals on demand for immediate redemption, and helps keep merchants bustling throughout the day.
Expect us to make ambitious bets on our future that distract us from our current business. Some bets we’ll get right, and others we’ll get wrong, but we think it’s the only way to continuously build disruptive products.
We are unusual and we like it that way.
We want the time people spend with Groupon to be memorable. Life is too short to be a boring company. Whether it’s with a deal for something unusual, such as fire dancing classes, or a marketing
