The Blob: slime mould and networks

 This week's science TV turned out to be fascinating. I'd noticed in the Biology text book I was reading that slime moulds don't fit in normal 5 Kingdom categories. I was interested that Toshiyuki Nakagaki at Hokkaido University is referred to as a biophysicist and I can see why because of the way he is using slime moulds to come up with optimal networks. You've got nearly a year to watch the programme https://www.bbc.co.uk/iplayer/episode/m00103fr/the-blob-a-genius-without-a-brain

Systematic error in reflection experiment

 This is how it should be. The angle of incidence from the normal line (90 degrees) is 50 degrees and so is the angle of reflection.

Here the mirror has not been set on its base line correctly. The incident ray is still where it was but the angle of reflection is 56 degrees. This is a SYSTEMATIC ERROR because every single reading made from now on will be 6 degrees out for the same reason.

Note that the mirror is only 3 degrees out along the base line. That moves the normal line by 3 degrees increasing the angle of incidence to 53 degrees although the incident ray looks as though it is in the same place. Hence the angle of reflection also increases by 3 degrees. 3 degrees on each side of the normal means the line seems to have moved by 6 degrees in total.

LED bollard lights

 Having seen a grey cone inside the pedestrian light bollard on the camp site during the day, I was interested to see how it worked.

Close up there was a circle of LEDs out of sight. I wondered whether the grey cone was fluorescent or just reflects. 

One reason for ruling out fluorescence would be that the LEDS emit visible light. The coating on a fluorescent tube is because the light emission process in the gas produces ultraviolet that we can't see. I suspect reflection because of what you can see in the two photographs. In the first photo I must have been at the angle to which the curve is designed to reflect. Dropping down to photograph the inside meant the angle wasn't correct and it wasn't as bright.

White-tailed lapwing: telescope eye ring or Airy Disc?

We went to see the White-tailed Lapwing at Blacktoft Sands. I have a primitive system of taking photographs through my telescope.

 

I have problems getting the camera aperture into the right place for a photograph and you get odd effects like the one below. 

My first thought was the Airy Disc for an aperture because it is a bright central disc. But it is a true image around the edge instead of the required black circle minimum. So is it to do with the eye ring of a telescope. The eye ring is put in place so that the eye is positioned at the place where all of the light from the objective lens is focussed: it all passes through a disc at that point. The total image disc is smaller for the this effect. I need to come up with a different way to test this.

A strange model of the ear

 

I made a functional model of an ear. The funnel is the pinna, focussing the waves into the cardboard tube that represents the ear canal. This takes the vibrating air inside the head where it hits the ear drum, represented by a stretched balloon. The whiteboard pen represents the ear bones and a balloon filled with water represents the cochlea with the wires representing the auditory nerve. The ear bones are necessary because when sound travels through gas to hit liquid most of it is reflected. This is why in an ultrasound scan, gel is put between the transducer and the body. In the ear, the bones act to stop this happening. I've seen it called an example of impedance matching. The way that the bones act as levers also magnifies the oscillation so in a sense the bones act as an amplifier.

This week's amazing TV documentary: neutrinos

 I can remember being told when I was at school about an experiment with a large vat of dry cleaning fluid deep underground and I've heard lectures on neutrino oscillations in recent years. But this week's BBC4 documentary explains it all really clearly https://www.bbc.co.uk/iplayer/episode/m000zwqr/neutrino-hunting-the-ghost-particle

Biomass of a sunflower

 This sunflower has been the subject of much speculation this summer as to how tall it is. We decided to find its biomass as well.

It was 3 metres 2ocm long.

We weighed it like this, having cleaned as much soil from the roots as possible.

Repeat readings for mass were 4.7kg, 4.6kg, 4.5kg and 4.4kg. The balance kept turning itself off. Not sure if there was some drift there but mean is 4.5kg if we round down.

Almost all of that is from carbon dioxide and water over the space of 4 months. It is a wet biomass because it has not been oven dried so contains liquid water. The flower head is about a quarter of the total mass.