Science Briefs: Lasers measure rare natural element

July 21, 2013 

Lasers measure rare natural element

The radioactive element astatine – its name is derived from the Greek word for “instability” – is so rare that it has not yet been investigated to any great extent and, as a consequence, very little is known about it.

Using artificially generated astatine, Germany-based physicist Sebastian Rothe has for the first time explored one of its fundamental parameters, the ionization potential, the amount of energy required to remove an electron from an atom’s outer shell. This determines the chemical binding characteristics of the element.

The measurements were undertaken at the laboratory of the CERN European Organization for Nuclear Research near Geneva, Switzerland, using special lasers developed by the LARISSA working group at the Institute of Physics at Johannes Gutenberg University in Mainz, Germany. The journal Nature Communications recently published the findings.

Astatine is the rarest naturally occurring element on Earth. The planet’s mantel is estimated to contain only 0.07 grams. Together with fluorine, chlorine and iodine, it is a member of the halogen group and is formed as a result of the natural decay of uranium.

Putting flowers at gravesites is a 13,700-year-old custom

The earliest evidence of using flower beds for burial, dating back to 13,700 years ago, was discovered in Raqefet Cave on Israel’s Mount Carmel, during excavations led by the University of Haifa.

In four different graves from the Natufian period, 13,700-11,700 years ago, dozens of impressions of Salvia plants and other species of sedges and mints were found under human skeletons.

“This is another evidence that as far back as 13,700 years ago, our ancestors, the Natufians, had burial rituals similar to ours, nowadays,” said Dani Nadel, from the University of Haifa, who led the excavations.

The Natufians were one of the first in the world to abandon nomadic life and settle in permanent settlements, setting up structures with stone foundations. They were also among the first to establish cemeteries – confined areas in which they buried their community members for generations.

Raqefet Cave is located in a national park. A paper on the findings was published in Proceedings of the National Academy of Sciences.

Long-lived mice do less and avoid risk

Risky behavior can lead to premature death – in humans. The University of Zurich’s Anna Lindholm and doctoral student Yannick Auclair investigated whether this also applies to animals by studying the behavior of 82 house mice.

They recorded boldness, activity level, exploration tendency and energy intake of female and male house mice with two different allelic variants on chromosome 17, thereby testing predictions of “life-history theory” on how individuals invest optimally in growth and reproduction.

The longer-lived t haplotype females proved less active.

They also consume less food, are less explorative and favor cautiousness and energy conservation, as predicted by theory.

According to the research team, female mice with a longer life expectancy follow the strategy “live slow, die old,” whereas those with a shorter life expectancy live according to the principle “live fast, die young.” University of Zurich

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