People with damage to the brain’s parietal lobe,
which integrates sensory information, don’t dream.
One hypothesis suggests that while we sleep,
the parietal lobe continues generating signals,
and our forebrain tries to make a story out of this activity.
Other researchers have suggested that dreams
occur when short-term memories are encoded
and moved to long-term memory, or when unwanted
connections are removed from memory.
Evolutionary psychologists contend that dreams
have a specific survival value. We mostly dream about
threats or stressful situations. This may be so we can
safely rehearse strategies for dealing with them. LVWHY DO
WE DREAM?
The number of genes
on the human
Y chromosome.
In comparison,
the X chromosome
has around 1,000.27
The speed, in km/h,
that cyclists should
travel at while
commuting, to avoid
breathing in too many
pollutants. Those who
cycle faster inhale up
to four times as much
air pollution because
they breathe more
he av i ly.13
IN NUMBERSThe number of distinct
academic families
that two-thirds
of the world’s
mathematicians
fall into24
Egg white is 92 per cent water, with a mixture of around 148 different
proteins, mainly ovalbumin, ovotransferrin and ovomucoid.
At room temperature, these proteins are held in a complex 3D globular
structure by sulphur bonds between the amino acids in the protein
chain. When the egg cooks, the heat causes the sulphur bonds
to come undone so each protein molecule unravels and gets tangled
up with its neighbours in a solid mass. This process happens at
77°C for ovalbumin. But, above 70°C, the sulphur also forms hydrogen
sulphide that reacts with iron in the egg yolk to form iron sulphide,
and this gives it a greenish grey colour. You can prevent this by running
the eggs under the cold tap to lower their temperature as soon as
they are cooked. LV
WHY DO HARD-BOILED EGGS
SOMETIMES GET A GREY
RING ROUND THE YOLK?
17 April 2017 April 2017^11