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In an unprecedented move against a fellow Arab nation, the Arab League on Sunday approved economic sanctions on Syria to pressure Damascus to end its deadly suppression of an 8-month-old uprising against President Bashar Assad.
Source: http://www.msnbc.msn.com/id/3036697/vp/45406375#45406375
ScienceDaily (Nov. 25, 2011) ? Physicists from the University of Stuttgart show the first experimental proof of a molecule consisting of two identical atoms that exhibits a permanent electric dipole moment. This observation contradicts the classical opinion described in many physics and chemistry textbooks.
The work was recently published in the journal Science.
A dipolar molecule forms as a result of a charge separation between the negative charged electron cloud and the positive core, creating a permanent electric dipole moment. Usually this charge separation originates in different attraction of the cores of different elements onto the negative charged electrons. Due to symmetry reasons homonuclear molecules, consisting only of atoms of the same element, therefore could not possess dipole moments.
However, the dipolar molecules that were discovered by the group of Prof. Tilman Pfau at the 5th Institute of Physics at the University of Stuttgart do consist of two atoms of the element rubidium. The necessary asymmetry arises as a result of different electronically excited states of the two alike atoms. Generally this excitation will be exchanged between the atoms and the asymmetry will be lifted. Here this exchange is suppressed by the huge size of the molecule, which is about 1000 times larger than an oxygen molecule and reaches sizes of viruses. Therefore the probability to exchange the excitation between the two atoms is so small that it would statistically only happen once in the lifetime of the universe. Consequently, these homonuclear molecules possess a dipole moment. A permanent dipole moment additionally requires an orientation of the molecular axis. Due to their size the molecules rotate so slowly that the dipole moment does not average out from the viewpoint of an observer.
Physicists from the University of Stuttgart succeeded in experimentally detecting the dipole moment. They measured the energy shift of the molecule in an electric field by laser spectroscopy in an ultra cold atomic cloud. The same group caused worldwide a stir when they created these weakly bound Rydberg molecules for the first time in 2009. The molecules consist of two identical atoms whereof one is excited to a highly excited state, a so-called Rydberg state. The unusual binding mechanism relies on scattering of the highly excited Rydberg electron of the second atom. So far theoretical descriptions of this binding mechanism did not predict a dipole moment. However, the scattering of the Rydberg electron of the bound atom changes the probability distribution of the electron. This breaks the otherwise spherical symmetry and creates a dipole moment. In collaboration with theoretical physicists from the Max-Plank-Institute for the Physics of Complex Systems in Dresden and from the Harvard-Smithonian Center for Astrophysics in Cambridge, USA, a new theoretical treatment was developed that confirms the observation of a dipole moment.
The proof of a permanent dipole moment in a homonuclear molecule not only improves the understanding of polar molecules. Ultra cold polar molecules are also promising to study and control chemical reactions of single molecules.
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The above story is reprinted from materials provided by University of Stuttgart.
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Source: http://feeds.sciencedaily.com/~r/sciencedaily/~3/i0HE36vKklA/111125160904.htm
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MEXICO CITY ? Six inmates from the last island penal colony in the Americas were recaptured at sea Thursday after they used buoyant containers and wood planks to try to swim to freedom in an escape reminiscent of the 1973 movie "Papillon."
The Mexican navy said the inmates used empty plastic gas or water tanks to help stay afloat as they swam about 60 miles (90 kilometers) south of the Islas Marias, a Mexican penal colony where inmates live in small houses and are normally not locked up. Prisoners can tend small gardens and raise food.
The six men were only about 60 miles from the Pacific coast resort of Puerto Vallarta when they were spotted by a passing boat early Thursday.
The boat called in a tip to a local naval base, and patrol boats were quickly dispatched to take the men into custody. Photos provided by the navy showed them men sunburned but alert ? and unhappy ? on the deck of the patrol vessel.
The men, who range in age from 28 to 39 years, were taken back to Puerto Vallarta for a medical check and to be turned back over to prison authorities.
Later, the federal Public Safety Department, which is in charge of Mexico's federal prisons, said the men had been found to be in acceptable health and would be returned to the penal colony "within hours."
The department said the prison oversight agency wasn't notified until Thursday that the men were missing from the prison ? the same day they were found at sea, suggesting that their absence had not been noticed when they set off on the escape bid.
The Islas Marias penal colony lies about 70 miles (110 kilometers) from the mainland, but the prisoners did not swim to the closest shore, which is due east. Instead they apparently swam south, either because prevailing currents carried them that way, they didn't know where they were going, or because they were aiming for Vallarta.
The Pacific ocean forms the main security barrier at the island. While dozens of prisoners are believed to have tried to escape since the penal colony was founded in 1905, local news media reports indicate few, if any, are believed to have made it to the mainland.
The escape bid drew comparisons to the movie "Papillon," in which the main character, played by Dustin Hoffman, uses a buoyancy device to swim away from a penal colony in French Guyana.
Islas Marias is the last island penal colony in the region.
Panama closed Coiba Island, the only other remaining island penal colony in the Americas, in 2004. That same year, Mexico announced it would spend $2 million to revive the crumbling prison at Islas Marias and increase the inmate population. Normally, about 1,000 to 1,200 inmates are held at the facility.
(This version CORRECTS that the Public Safety Department, not the Interior Department, released information about the men being returned shortly to the penal colony. )
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PESHAWAR, Pakistan (Reuters) ? Pakistan on Sunday buried 24 troops killed in a NATO cross-border air raid that has pushed a crisis in relations with the United States toward rupture.
The attack was the latest perceived provocation by the United States, starting with the secret raid which killed al Qaeda leader Osama bin Laden in May, and the question is whether ties will break or whether the two sides will remain stuck in a bad marriage of convenience.
NATO helicopters and fighter jets attacked two Pakistan military outposts on Saturday, killing the soldiers in what Pakistan said was an unprovoked assault.
NATO and U.S. officials expressed regret about the deaths of the Pakistani soldiers, but the exact circumstances of the attack were unclear.
"U.S. stabs Pakistan in the back, again," said a headline in the Daily Times, reflecting fury over the attack in Pakistan, a regional power seen as critical to U.S. efforts to stabilize neighboring Afghanistan.
Television stations showed the coffins of the soldiers draped in green and white Pakistani flags in a prayer ceremony at the headquarters of the regional command in Peshawar.
Pakistan shut down NATO supply routes into Afghanistan - used for sending in nearly half of the alliance's land shipments - in retaliation for the worst such attack since Islamabad uneasily allied itself with Washington following the September 11, 2001, attacks on the United States.
That is unlikely to cool tempers in a country where anti-American sentiment runs high even when ties between Islamabad and Washington are smooth.
About 500 members of Jamaat-e-Islami, Pakistan's most influential religious party, staged a protest in Mohmand tribal area, where the NATO attack took place.
"Down with America" and "Jihad is The Only Answer to America," they yelled.
Around 40 troops were stationed at the outposts t the time of the attack, military sources said. Two officers were reported among the dead.
"They without any reasons attacked on our post and killed soldiers asleep," said a senior Pakistani officer, requesting anonymity.
BLUNT STATEMENTS
The border is often poorly marked, and Afghan and Pakistani maps have differences of several kilometers in some places, military officials have said.
Pakistan responded with unusually blunt statements condemning the incident as a violation of its sovereignty and it reserved the right to retaliate.
Pakistan is a vital land route for nearly half of NATO supplies shipped overland to its troops in Afghanistan, a NATO spokesman said. Land shipments account for about two thirds of the alliance's cargo shipments into Afghanistan.
A similar incident on Sept 30, 2010, which killed two Pakistani service personnel, led to the closure of one of NATO's supply routes through Pakistan for 10 days. NATO apologized for that incident, which it said happened when NATO gunships mistook warning shots by Pakistani forces for a militant attack.
U.S. efforts to repair ties with Pakistan have suffered several big setbacks starting with the unilateral U.S. special forces raid that killed bin Laden in a Pakistani town where he had apparently been living for years.
Pakistan condemned the secret operation as a flagrant violation of its sovereignty, while suspicions arose in Washington that members of Pakistan's military intelligence had harbored the al Qaeda leader.
The military came under unprecedented criticism from both Pakistanis who said it failed to protect the country and American officials who said bin Laden's presence was proof the country was an unreliable ally in the war on militancy.
Pakistan's army, one of the world's largest, may see the NATO incursion from Afghanistan as a chance to reassert itself, especially since the deaths of the soldiers are likely to unite generals and politicians, whose ties are normally uneasy.
Pakistan's jailing of a CIA contractor, Raymond Davis, and U.S. accusations that Pakistan backed a militant attack on the U.S. embassy in Kabul have added to the tensions.
"From Raymond Davis and his gun slinging in the streets of Lahore to the Osama bin Laden incident, and now to the firing on Pakistani soldiers on the volatile Pakistan-Afghan border, things hardly seem able to get any worse," said the Daily Times.
Islamabad depends on billions in U.S. aid and Washington believes Pakistan can help it bring about a peace in Afghanistan ahead of a combat troop withdrawal at the end of 2014.
"The fact is that such incursions of our sovereignty have become routine and we have become so dependent on the U.S. that we just have to grin and bear it," said an editorial in Pakistan's Express Tribune.
(Additional reporting by Zeeshan Haider in Islamabad and Ijaz Mohmand in Peshawar; Writing by Michael Georgy; Editing by Chris Allbritton)
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