Wednesday, May 20, 2009

The nuclear reactor at Chalk River, Ontario in Canada was shut down on Thursday, May 14 by the Atomic Energy of Canada Limited (AECL) due to a leak of heavy water. Government officials say that by Saturday the demand for medical isotopes will no longer be met, due to the shortage caused by the closure.

Medical isotopes are used in diagnostic procedures for cancer, heart disease and other medical conditions. When radioactive isotopes are injected into the body, radiologists can view higher radiation via medical imaging, enabling them to make a more accurate diagnosis.

Estimates suggest that the reactor will be shut down for approximately one month for repairs. The Chalk River Laboratories produce 33% of the international supply of medical isotopes.

Lisa Raitt, Natural Resources Minister said, “A secure supply of medical isotopes is not only an issue for Canada, it is an international issue that is being addressed co-operatively by all isotope-producing countries.”

“It may mean that if you have an elective study booked … that patient is going to be deferred and will have to wait until the situation is resolved. I’m reasonably confident that for most patients, if they’re having an acute problem, that problem is going to be dealt with – and the greater the acuity, the more likelihood it’s going to be dealt with quickly and expeditiously,” said Dr. Karen Gulenchyn, a nuclear medicine expert.

“The government of Canada is engaging international isotope producers as well as companies such as MDS Nordion, Lantheus, and Covidien, who all play key roles in securing medical isotope supply for North America,” said Raitt and Health Minister Leona Aglukkaq.

In December 2007, the 52-year-old reactor was shut down and the Canadian House of Common stepped in to restart the reactor.

Thursday, January 12, 2017

United States President Barack Obama gave his official farewell address on Tuesday night from McCormick Place in Chicago, reflecting on personal and national accomplishments. This is expected to be his last major speech before officially handing the reins to president-elect Donald Trump on January 20.

Obama’s speech was wide-ranging. He thanked his family and the nation, spoke of the need for unity, noted the country’s accomplishments and need for improvement in areas like education and civil rights, and spoke about the need for pride in U.S. accomplishments, citing milestones of U.S. history and of his presidency specifically. “It’s why GIs gave their lives at Omaha Beach and Iwo Jima; Iraq and Afghanistan – and why men and women from Selma to Stonewall were prepared to give theirs as well.”

The president also addressed his country’s troubled history with race and racism, an issue many black citizens feel he has avoided. Despite this, Chauncy Devega of Salon described the president as “a role model of calm, cool reflective black masculinity: a man utterly at home in his own skin.” Obama described the concept of a post-racial U.S. “unrealistic” and particularly cited the need for reform in education and the criminal justice system and greater acceptance of scientific evidence, particularly evidence supporting action to counteract climate change.

However, publications including The Washington Post and Salon have given particular focus to another aspect of the president’s address: the country’s increasing political tensions and controversies involving access to news and information, both accurate and inaccurate. “We become so secure and our bubbles,” said Obama, “that we start accepting only information, whether it’s true or not, that fits our opinions instead of basing our opinions on the evidence that is out there,” calling this trend “a third threat to our democracy.”

The Washington Post characterized Obama’s comment, “If every economic issue is framed as a struggle between a hard-working white middle class and an undeserving minority, then workers of all shades will be left fighting for scraps while the wealthy withdraw further into their private enclaves,” as a “not-so-subtle jab” at the campaign tactics of President-elect Donald Trump. The Telegraph describes Obama’s warnings about the need to protect democracy as “a thinly veiled slight to the divisive rhetoric of Donald Trump’s election campaign, which included attacks on Muslims, the disabled, women and immigrants.” The president went on to call on the public to “reject the first dawning of every attempt to alienate any portion of our country from the rest or to enfeeble the sacred ties that make us one America. We weaken those ties when we allow our political dialogue to become so corrosive […] We weaken those ties when we define some of us as more American than others when we write off the whole system as inevitably corrupt and when we sit back and blame the leaders we elect without examining our own role in electing them. It falls to each of us to be those anxious, jealous guardians of our democracy.”

Despite this, when the mention of Donald Trump brought boos from the crowd, Obama reiterated the importance of the long history of peaceful transfers of power from one president to the next: “No no no no no. […] I committed to President-elect Trump that my administration would ensure the smoothest possible transition, just as President Bush did for me.” However, this was not unaccompanied by a call to action. Near the end of the speech, he insisted citizens dissatisfied with elected officials should “lace up your shoes, grab a clipboard, get some signatures and run for office yourself.”

Overall, the departing president’s speech focused on accomplishment, echoing the “Yes we can” slogan from his 2008 campaign: “If I have told you eight years ago, that America would reverse a great recession, reboot our auto industry, and unleash the longest stretch of job creation in our history. If I had told you, that we would open up a new chapter with the Cuban people, shut down Iran’s nuclear weapons program without firing a shot, take out the mastermind of 9/11[…] If I had told you that we would win a marriage equality and secure the right to health insurance for another twenty million of our fellow citizens. If I had told you all that, you might have said our sights were set a little too high. But that’s what we did.”

But when the crowd began shouting “Four more years! Four more years!” Obama, with a small laugh, answered, “I can’t do that.”

Sunday, August 29, 2010

A University of Tokyo group of researchers, led by bioengineer Shoji Takeuchi, has made an electronic sensor capable of smelling gases. The sensor uses genetically engineered frog cells. Since previous sensors were not very accurate, the scientist decided to try a biological approach. The invention was revealed in a US scientific journal yesterday, and is supposed to be used to design better machines to detect polluting gases in the atmosphere.

Previous smell sensors were based on quartz rods, which vibrate when a substance binds to them. The gases are distinguished by their molar masses, which can be similar for molecules with different structure, thus relatively often triggering a false positive. Trying to find a more accurate solution, Takeuchi decided to follow an example from insect world. As he explained, “when you think about the mosquito, it is able to find people because of carbon dioxide from the human. So the mosquito has CO₂ receptors. When we can (extract) DNA (from the mosquito) we can put this DNA into the frog eggs to detect CO₂.”

Genes of several insects (the silk moth, diamondback moth and fruit fly), injected into African clawed frog Xenopus laevis eggs, allowed them to produce relatively inexpensive and useful sensors. The choice of the species was caused by their widely studied and well-understood protein expression mechanism.

The modified cells responded to three kinds of pheromones and one odourant, which have similar chemical properties. When a molecule of an odorous substance adhered to the receptor on the membrane protein, ion channels opened for a certain period of time, and a current was generated. Its magnitude was clearly different for all four tested substances, allowing to distinguish between them accurately.

The colleagues embedded the sensor into a mannequin, so that it could shake its head when a gas was detected. It was easier to observe. Pheromones and molecules with quite similar molecule structure produced clearly distinguishable reaction, with higher accuracy than other biological or human-made sensors. As the research group said, the detection sensitivity of the odor sensor is several tens of parts per billion (ppb), and it is as high as the sensitivity of an existing odor sensor that uses an oxide semiconductor. The distinctive feature of the new sensor is its capability to selectively detect some odorous substances, rather than its sensitivity. Very few false positives were possible due to the biological mechanism involved.

At normal temperature, the sensor lifetime is about 12 hours, which can be extended by putting it into a refrigerator before first use.

Shoji Takeuchi says has a great hope for research use in future, since the frog eggs are very practical for genetic engineering, and can be conveniently used to develop smell sensors for a wide range of gases. He said, “The X. laevis oocyte has high versatility for the development of chemical sensors for various odorants. We believe that a shared ability to smell might open a new relationship between man and robot. .. The research will have wide implications… If the sensor is embedded in a nursing robot, it will be able to identify certain mouth odors or body odors. Also, it can be used for detecting CO₂, air pollution, water pollution and food. It’s very important for the environment.”