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Earth’s core mystery still unresolved

A new study suggests that the differences between the east and west hemispheres of the Earth’s core are explained by the way iron atoms pack together.

Lying more than 5,000km beneath our feet, at the centre of the Earth, the core is beyond the reach of direct investigation. Broadly speaking, it consists of a solid sphere of metal sitting within a liquid outer core.  The inner core started to solidify more than a billion years ago. It has a radius of about 1,220km, but is growing by about 0.5mm each year, the BBC reported.
But the stuff that the core is made from remains a longstanding unresolved problem.
Clues come from the speeds that seismic waves generated by earthquakes pass through the core.

These tell us its density and elasticity, but the precise arrangement of iron atoms forming the crystalline core controls these numbers. How those atoms are arranged remains unclear, since the conditions of extreme pressure and temperature at the core cannot easily be replicated in the laboratory. Seismic data indicate that the western and eastern hemispheres of earth’s inner core differ, and this has led some to suggest that the core was once subjected to an impulse - presumably from the collision of a space rock or planetoid which shook the whole earth. The core, it is suggested, is constantly moving sideways. As it does, the front side is melting and the rear side crystallising, but the core is held centrally by gravity.

With all these seismic complexities, the link between the crystal structure and the geophysical observations has yet to be resolved.

Anti-diet programme promises healthier lifestyle

A school teacher from New Zealand is embarking on a 40-week nutrition and exercise programme where he will not diet but will address the underlying causes behind his poor lifestyle.

According to physical education lecturer Jeremy Hapeta, Palmerston North Boys’ High School teacher Justin Doolan’s anti-diet approach is aiming to improve physiological health measures, like blood pressure and fitness, and psychological aspects rather than simply to lose weight, Stuff.co.nz reported.

45-year-old Doolan spent the first half of his life as an athlete, which included nine years as a professional rugby player in Japan, but coming home for teachers’ college in 1999 resulted in his abs turning to flab.

And before he knew an extra 50kg crept on to his body.

The “anti-diet” programme developed by physical education lecturer Jeremy Hapeta, management lecturer Andrew Dickson, human nutrition lecturer Jasmine Thomson and human development lecturer Cat Pause, addresses nutrition, exercise, attitudes about health and acceptance of fatness.

Thomson said that Doolan would be encouraged to change his relationship with exercise and food, including retraining himself to realise when he was hungry or full.

Brain tumours in children have a common cause

Scientists have found that an overactive signalling pathway is a common cause in cases of pilocytic astrocytoma, the most frequent type of brain cancer in children. Scientists coordinated by the German Cancer Research Center (as part of the International Cancer Genome Consortium, ICGC) in 96 gemone analyses of pilocytic astrocytomas found defects in genes involved in a particular pathway. They believe that drugs can be used to help affected children by blocking components of the signalling cascade.

Pilocytic astrocytomas are the most common childhood brain tumours. These tumours usually grow very slowly. However, they are often difficult to access by surgery and cannot be completely removed, which means that they can recur.

In previous work, researchers led by Professor Dr Stefan Pfister and Dr David Jones had already discovered characteristic mutations in a major proportion of pilocytic astrocytomas.
All of the changes involved a key cellular signalling pathway known as the MAPK signalling cascade. MAPK is an abbreviation for ‘mitogen-activated protein kinase’. This signalling pathway comprises a cascade of phosphate group additions (phosphorylation) from one protein to the next - a universal method used by cells to transfer messages to the nucleus.
“A couple of years ago, we had already hypothesised that pilocytic astrocytomas generally arise from a defective activation of MAPK signalling,” said Jones, first author of the study in journal Nature Genetics. “However, in about one fifth of the cases we had not initially discovered these mutations. In a whole-genome analysis of 96 tumours we have now discovered activating defects in three other genes involved in the MAPK signalling pathway that have not previously been described in astrocytoma,” he said.

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