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OpenLearn Live: 21st April 2016

Updated Thursday 21st April 2016

A better way to measure time. Then more free learning through the day.

Making sense of "free learning" by bringing it into the heart of your world. This page will be updated across the day.

Yesterday, we caught up with the EU referendum, US elections and Scottish polls

See the complete collection of OpenLearn Live


Today's posts


Of mice and men

Why do we test drugs on animals? The theory runs that if you slip a mouse a new drug, mice are near-enough to people so that watching how the drug affects the mouse will give you an idea of what would happen if you gave it to a person. Except it isn't quite that simple - new research (published in Nature) suggests that because test mice are kept in incredibly clean labs, their circumstances might mean they're not really that similar enough to people.

The Economist explains why this is something of a problem, and not simply for the mice being experimented upon:

Billionaires including Michael Bloomberg, an ex-mayor of New York, and Sean Parker, co-founder of the file sharing service Napster, have given millions of dollars towards immunotherapy research and work in the area is expected to be a funded under the American government’s new $1 billion ‘cancer moonshot’. Yet testing future therapies on lab mice with the immature immune systems that Dr Masopust’s work reveals is unlikely to indicate how they will perform in humans.

Read the full article at The Economist More evidence emerges of how laboratory rodents can skew research [Requires Registration]

Read the full research at Nature


Seahorses: swimming and swinging

If you're still coming to terms with our genderqueer lions from earlier in the week, you might want to skip this item. Because it turns out the seahorses - which you might have heard mate for life - behave differently in captivity. Seahorses which lose their partner can, normally, appear to go into something of a funk. Except...

At Ocean Rider's farm, this is a problem they don't face all that much. On the tour, the guide motions to a tub of tiny seahorse babies drifting in small, sociable clouds and declares: "We have a created a domesticated seahorse that doesn't die of loneliness." One way that Ocean Rider has done this is by raising the seahorses not in pairs as they live in the wild, but in groups. "Non-monogamy is just something that naturally happens when you are raising young adults together at greater population densities than they ever experience in the wild," Giwojna explains. "The seahorses are surrounded by prospective partners at all times."

In effect, then, these seahorses are being raised in an environment akin to a really overcrowded nightclub on a Saturday night, with broadly similar results.

Read the full article at Wired: These seahorses have given up on monogamy

Try your hand at selective breeding with our Angel Breed game


The language of The Jungle Book

Ahead of the new film version of Rudyard Kipling's Jungle Book, the Oxford Dictionaries blog has explored the way Kipling used language - and expanded it, too:

Kipling’s vocabulary is marked by numerous borrowings from Indian languages (Kipling was in fact born in India, and returned there after completing his education in England). He is the first recorded user of cushy, or khushi (from Urdu ḵušī ‘pleasure’), to mean ‘relaxed, easy-going’; this word was later popularized in the military slang sense of a job requiring little effort but with considerable rewards – a cushy number. The Hindi word bat ‘speech’ appears in the phrase speak or sling the bat, meaning to talk the local patois. Local practices are described using Hindi terms such as machan: a platform made of sticks at the top of great poles on which men sat to scare away birds, kajawa: ‘a camel-litter for women’, pheeal, ‘the shriek made by jackal on the hunt’, and the dubious hygiene practice of leeping ‘washing with dung and water’. There are words that reflect local beliefs, such as jadoo ‘magic, enchantment’ and churel, defined chillingly in Kim as ‘the peculiarly malignant ghost of a woman who has died in child-bed. She haunts lonely roads, her feet are turned backwards on the ankles, and she leads men to torment’.

Read the full article at Oxford Dictionaries Blog

Discover how to study Children's literature with The Open University


Fifties forward: Atomic Clocks

This week, we're catching up with some icons of the fifties that are still going strong today. Yesterday, we heard about Lord Of The Flies. Today, it's atomic clocks.

NBS Atomic Clock Copyright free image Icon Copyright free: National Institute of Standards and Technology

For most of human existence, time was measured by looking at where the planet had got to as it moved around. One rotation on its axis, and that's a day. Or a sidereal day, at least. That's good enough when you're working out when to get up in the morning, or when Coronation Street's on.

But the Earth is a pretty useless clock if you're trying to measure things really, really accurately. Partly because it turns irregularly - through much of the 19th Century, it ran a second fast each year; as the 20th Century got underway, it started to run slow. And what if you're trying to measure time elsewhere in the Universe?

Quartz clocks had offered something better - but not good enough for astronomical purposes.

Enter the atomic clock. There had been one built in the 1940s, by the US National Bureau Of Standards. Based on ammonia maser, it was more of proof-of-concept than a solution, because it was less accurate than the best quartz clocks at the time.

In 1955, though, Britain stepped forward with the first atomic clock based on Caesium-133:

In 1955, Louis Essen and Jack Parry designed and built the world's first caesium atomic clock at NPL in Teddington, transforming the way we measure and use time.

So, how exactly do atomic clocks work? The NPL explains them like this:

Every atom is composed of a nucleus, which contains the atom’s protons and neutrons (collectively known as nucleons). Orbiting that nucleus are the atom’s electrons, which occupy different orbits, or energy levels.

By absorbing or releasing exactly the right amount of energy, the electrons can ‘jump’ from one energy level to another. This is called a transition. The electrons absorb energy to move to a higher energy level (away from the nucleus), and release energy to move down an energy level (towards the nucleus).

The energy released or absorbed in these transitions takes the form of electromagnetic radiation (e.g. visible light or microwaves). The same amount of energy is released every time the same transition occurs, no matter where or how many times it is measured.

As with all waves, the radiation has a certain frequency (i.e., it completes a certain number of full waves in a second, similar to the way a pendulum completes a certain number of swings in a minute) and this frequency can be measured. This means that a clock can be based on the wave frequency of an electron’s transition energy in an atom, in a similar way to a clock based on the swinging of a pendulum.

Here's a video which might help you picture that:

There's now a network of atomic clocks around the planet, synchronised to an accuracy of 10-9 seconds a day, to provide a solid scientific answer to the question 'what's the time?'. That's incredibly accurate - but probably too accurate for deciding when to pop a pizza in the oven. So for 'civilian' time, there's a slightly less accurate version, co-ordinated universal time (UTC), which is tweaked every so often to keep it in closer synchronisation with the time that you'd get if you were still using the Earth as your timepiece - hence the addition of leap seconds every so often to line them up.

Understand why science needs solid numbers with this extract from our free course

 

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