Friday 13 December 2013

How nuclear bombs tell us the age of human cells, used to identify Tsunami victims


When mushroom clouds exploded in the sky during Cold War-era nuclear bombs testing, they also created an unexpected boon for science. The nuclear explosions caused a massive uptick in Carbon-14 that eventually settled in all living tissue — everything from tree rings to elephant tusks to human brain cells.

As such, this spike in Carbon-14 has helped scientists date trees, find ivory poachers, and upend a decades-old dogma that new brain cells cannot be regenerated in the human brain.

In fact, Kirsty Spalding and Jonas Frisén, the pioneering brain cell researchers profiled by PBS’s NOVA, believe Carbon-14 dating has great potential for shedding light on how quickly cells are replenished in the body.

The catch is that the Carbon-14 released before the aboveground nuclear testing ban in 1963 is slowly fading to background levels. There’s plenty of research yet to be done — but they only have until 2050.

As Carrie Arnold explains for NOVA, this is why Carbon-14 or so-called bomb pulse dating works:

Most aboveground nuclear bomb testing happened between 1955 and 1963, and those detonations released untold numbers of neutrons into the atmosphere. These slammed into nitrogen atoms, causing their nuclei to eject a proton. What was once a seven-proton nitrogen became a six-proton carbon. But unlike most carbon atoms, which have six protons six and neutrons, this radioactive carbon, known as 14C, retained nitrogen’s two extra neutrons, a difference in atomic mass that is small, but measurable. Normally, only a tiny fraction of the world’s carbon is 14C, so little that scientists measure it in parts per trillion. The bomb pulse doubled this amount. While 14C concentrations are still low even after the bomb pulse, the difference is obvious to scientists who know what they’re looking for.

The use of Carbon-14 dating in biology was originally forensic. Because skin and hair are continually replenished in a live person, their age — as determined by Carbon-14 dating — is also a proxy for when a person died. Spalding and Frisén used Carbon-14 to help identify victims of the Indian Ocean tsunami, for example, but they were eventually convinced the technique could be used to date populations of cells as well as whole bodies. By looking at the age of cells, they could also figure out how quickly those cells replenished.


When they started looking at certain tissues, Spalding and Frisén first found that fat cells were replaced more quickly in the obese than the healthy. When they turned their attention to the brain, they found that some neurons were younger than the individuals they came from, thus showing that the brain can, in fact, regenerate, a discovery indirectly made possible due to the atmospheric effects of nuclear bombs.

Friday 13 December 2013

http://www.gizmodo.com.au/2013/12/how-nuclear-bombs-tell-us-the-age-of-human-cells/

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Police probe plane crash pictures release


Police are investigating how pictures of the Mozambican plane, which crashed in northern Namibia about two weeks ago, were released in the media without authorisation.

Both Police Deputy Commissioner Edwin Kanguatjivi and Director of National Institute of Forensic Science Paul Ludik concurred during a press conference in Windhoek on Wednesday that publishing the images was unethical since it interfers with the course of justice.

“We realise these photographs and videos are very graphic,” said Kanguatjivi, adding that they are investigating how such ‘unauthorised release’ of pictures occurred in the first place.

“The unauthorised usage of photographic images emanating from crime scenes could be construed as interfering with the course of justice,” said Ludik.

According to Police Deputy Inspector General James Tjivikua, the crash is still under investigation to ensure accurate identification of all deceased.

“The investigation should take approximately 14 days as the Institute of National Forensic Science is attempting to make identification through comparison of dental and fingerprint records available prior to the crash,” said Tjivikua.

Initial information had suggested that there were 33 people on board the LAM flight from Maputo to Luanda, Angola on 29 November and that only 31 bodies were found.

LAM spokesperson Norberto Mucopa, also expressed concern, in a press statement issued on Tuesday, about worldwide media speculation, in reference to some claims that some passengers had evacuated before the crash and that two bodies were also not accounted for.

“LAM is concerned about these speculation as they are causing anxiety, upset and uncertainty locally,” said Mucopa, adding that family members have been of assistance during the investigation process.

Friday 13 December 2013

See more at: http://www.namibian.com.na/indexx.php?id=7205&page_type=story_detail&category_id=1

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