Why do cats like boxes?

They're the YouTube classics which rack up potentially millions of views, cats sliding around the living room in boxes - but why do they have this obsession?
In the wild, cats hide in bushes or burrows during the day to escape their many predators. Scientists believe that it's this trait which lingers in domestic cats. Studies have indicated that cats in animal shelters feel far more comfortable if they had a box to hide in. Even when cats aren't stressed it still can make them feel more comfortable and secure.

AS Physics - Electron Diffraction

(for AQA AS Physics)

• Electron diffraction shows the wave nature of electrons (how electrons can behave like waves)
• Diffraction patterns are observed when accelerated electrons in a vacuum tube interact with the spaces in a graphite crystal - this confirms electrons show wavelike properties
• According to the wave theory - the spread of the lines in the diffraction pattern increases if the wavelength of the wave is greater
• In experiments: a smaller accelerating voltage (the electrons are slower which gives widely spaced rings
• Increase in the electron speed - the diffraction pattern circles squash together towards the middle. (fits with the de Broglie equation  - if velocity is higher the wavelength is shorter and the spread of the lines smaller)

Wavelength for electrons accelerated in a vacuum tube is about the same size as electromagnetic waves in the X-ray part of the spectrum

A level Physics: Wave Particle Duality

• Light is part of the electromagnetic spectrum
• The theory of the electromagnetic waves predicted the existence of waves beyond visible light (before we knew about x-rays and so on)
• The discovery of x rays and radio waves confirmed their existence (and their predictions)
• Many scientists in the late 19th Century thought that all aspects of physics could be explained through Newton's laws of motion. 

Interference and Diffraction show light as a wave

• Light produces interference and diffraction patterns - these are alternating bands of dark and light
• Can only be explained using waves interfering constructively or interfering destructively

Constructive Interference - when two waves overlap in phase

Destructive interference - when two waves are out of phase

Although - Particles DON'T show wave-like properties all the time

Diffraction only happens if a particle interacts with an object about the same size as the de Broglie wavelength

de Broglie came up with the wave-particle duality theory

shorter wavelength = less diffraction effects (this fact is used in electron microscopes)
Diffraction effects blur detail on an image 

(specifically for AQA A-level physics specification A)

Andy Murray's 500 career wins

Andy beat Kevin Anderson about a fortnight ago during the Miami open, and with his wedding to Kim Sears on Saturday I thought i'd look at what it's taken for Andy to become the world number 3.

Science this year...

We're virtually four months through the year and a lot has happened, so here is your four month round up of all the latest, and ever continuing developments in the world of science. 

Scientists have begun to start communication once more with the Philae lander on the Rosetta Comet. Last year scientists achieved the impossible as they managed to land Philae on the moving Rosetta comet. Unfortunately late last year the lander lost power but scientists are now hoping the lander will receive enough sunlight to recharge the batteries using the solar panels on the lander. 

Scientists have also commenced the #missiontohell, sending a probe inside the orbit of mercury, venturing well beyond what we've ever done before, all through enormously high temperatures! 

Lunar Mission One have also issued a status update on the 10 year long mission to the moon to study the full depth of the moon's surface. 

And only today in fact the king who changed the potential status of the whole monarchy was reburied. He gave us an incredible insight to the genes of the royals and they traced his genes though many generations to find a living descendent so they could in fact confirm this was Richard III. There were also surprising revelations over the King himself, that he did in fact have scoliosis, (curvature of the spine) 

Also today there has been revelations that the co-pilot of the crashed German wings plane wanted the plane to descend. This poses millions of questions as to why this actually happened, even should that kind of control go to the pilots? 

As we begin to look towards the second half of the year, British astronaut Tim Peake enters the final stages of his training to become an astronaut on the ISS for 6 months, doubtless following in the footsteps of Chris Hadfield. 

Whatever you think about science, this year, in its relatively early stages has brought up a whole load more developments and will continue to do so throughout the rest of 2015.

to be continued...  

#eclipse2015 - As it happened

Unfortunately the British weather let us down - it was very cloudy! Although it did get darker as 83% of the sun was blocked by the moon everywhere in the UK. Because we didn't actually see anything I thought I would round up some of the stunning images which have been circling on twitter and the internet today.

Here's a round up of what happened from the Telegraph

A-Level Revision - The Cell Surface Membrane

These revision notes refer to AQA AS Biology Chapter 3.5

 The cell surface membrane is another name for the cell membrane or plasma membrane.
- It surround the cell boundary between the cell cytoplasm and the environment (this is where there is different conditions inside and outside of the cell).

The Fluid Mosaic Model

Why is this called the fluid-mosaic model?
Fluid - The Molecules move relative to one another
Mosaic - means being made up of different substances, in this case proteins and phospholipids.

How do substances pass through a cell membrane?
(a very common exam question)

- the phospholipids form a bilayer
- the phospholipids are arranged with hydrophilic heads on the outside and hydrophobic tails on the inside
- There are two types of proteins, some are passing through and some are confined to one layer
- There are other molecules present, for example: cholesterol or glycoproteins
- substances are moved DOWN the concentration gradient (from a high to low concentration)
- water and ions move through the channel proteins
- lipid soluble molecules are passed between the phospholipids
- carrier proteins are involved in facilitated diffusion.

The Solar Eclipse

Before I start I will mention a huge safety warning - don't look directly at the sun without protection, this may damage your eyesight!

Tomorrow, we will have a solar eclipse, where the sun's light is partially obscured (or totally obscured) by the moon, here in England, around 94% of the sun's light is expected to be obscured, although in typical British fashion it's meant to be cloudy which makes viewing the eclipse very difficult! Having said that, we will still be in relative darkness for about 90 minutes. It's the first time this has happened for 15 years. 

If you're interested in actually viewing or photographing the eclipse then take a look at this information - http://www.bbc.co.uk/guides/zcytpv4

If you're hoping the next one is fairly soon, it's actually in over 10 years time! You can view the next 7,000 years worth of solar eclipses here- http://eclipse.gsfc.nasa.gov/solar.html, although you might be in for a bit of a wait for the next one! 

How to Walk the Nile

The man who conquered the Nile, Levison Wood battled through blisters and exhaustion, he walked the length of the Nile, through war zones and completely deserted regions of Africa. He had to bypass a small section of the Nile because he found himself caught in the midst of a civil war in South Sudan, he also battled through temperatures as high as 62C, he raced to reach a well in the desert through dwindling water supplies, but he made it, 9 months and thousands of miles later. 

Lev had to stay hydrated, walking with guides and journalists covering his adventure, unfortunately an American journalist, Matthew Power collapsed due to heatstroke, hours away from help he died, Lev carried on, dedicating the rest of the expedition to Matthew and his wife Jess. The tragic incident was a stark reminder of the physical challenge which lay ahead, not only to get to the end of the Nile but simply to survive. 

Lev, a former British Army Captain was used to being around in war but he said this was like nothing he'd ever seen, he said "One guy tried to attack me, and threatened to kill me", in the Channel 4 series, he talked about the fact he became a target because they wanted to attack anyone accosiated with the UN, potentially supporting the other side. 

Months later he completed his expedition, although his hopes for being the first to walk the length of  the Nile were ended after he was forced to skip a 400 mile war torn stretch of the Nile. 

As he entered Egypt, he viewed it as a kind of respite, although he was consistently followed by two police cars and a personal bodyguard, all to protect him from extremist groups or any other problems which may have occured. Throughout the trip, he explored some of the treasures of Africa, even some pyramids that a Pharoh blew the tops off to hunt for treasure - all to no avail, as he found treasure in only one of the pyramids! 

So how do you walk the Nile? The answer? Walking the Nile is a battle, a battle with the elements, a physical and mental battle and certainly not for the faint hearted,with temperatures averaging 50C it's about staying hydrated, drinking as much water as humanly possible - but as Lev has proved, it's all possible. 

Levison's book, Walking the Nile is available to buy from all well known book stores and Amazon