#pitting

Oedema is swelling due to excess fluids in tissues.

In pitting oedema, pressing on the affected area leaves an indentation (that persists after removing the pressure). In non-pitting oedema, the area feels firm to touch and does not form indentations.

Pitting oedema:

The excess fluid is mainly composed of water

Commonly caused by heart failure, venous insufficiency, or nephrotic syndrome

Non-pitting oedema:

The excess fluid consists of water WITH protein and salts

Usually indicates a condition of the thyroid / lymphatic system

Different types:

Lymphoedema is due to a build-up of lymphatic fluid (e.g. due to a tumour blocking lymphatic flow / after removal of lymph nodes).

Myxoedema occurs in hypothyroidism and often affected the pretibial or periorbital area.

Angioedema is localised swelling of the skin and is usually due to allergic reactions. It typically affects the face, tongue, larynx, abdomen, arms, and legs. When the larynx is affected, it may affect breathing, which is an emergency!

Lipoedema is when fat accumulates in subcutaneous tissues - it usually affects the legs/buttocks and almost exclusively occurs in postpubertal females (not the same as cellulite!)

Is that really sand?

Yes, these are actually sand grains, but not the kind of sand you’re used to seeing. The large majority of sand grains on the planet Earth are the mineral quartz, but these aren’t.

Quartz has properties that make it very common in sand. Quartz is very stable against chemical weathering, so when quartz in in a rock, other minerals tend to weather out first, leaving nothing but quartz behind. Quartz is also very strong against physical weathering, so when sediments are transported downstream, angular quartz grains tend to survive while other minerals are reduced to fine powder and dust.

In order to make a pile of sand composed of something other than quartz, the sediment must be dominated by something else. Sometimes sand can be composed of a mixture of feldspar and quartz since feldspar is “almost as resistant as quartz but not quite” – that creates a rock known as an arkose.

At the far end though, in areas where there is no quartz and no feldspar present, sand grains can be made of whatever rocks there are in the area. Those sand grains show up because erosion is really good at reducing rocks to sand grains, we just don’t see rocks dominated by sands of anything other than quartz or feldspar if those minerals are present.

The most famous examples of sands that aren’t quartz are black sand beaches like those in Hawaii. Those sands made of basalt, igneous rock broken apart into sand by the action of water. These grains come from a black sand beach in New Zealand, produced by the same processes – erosion of basaltic igneous rocks and no supply of quartz or feldspar.

The most unusual thing about this view to me is that the sand grains look nothing like quartz. Quartz sand grains are so often angular - quartz does not have any strong cleavage directions, so when it does break it tends to break in extremely sharp, angular fragments. Instead, these sand grains are not only rounded, they’re pitted. The basaltic rock that made these has interacted with water on the surface, leaving this rounded texture with no sharp points and lots of dissolution pits along it. The different colors in this image could either be caused by slightly different colors/mineral assemblages or just by how the light from the camera is caught.

Really amazing to see how different these sand grains are from quartz sand grains.

-JBB

Image credit: Microscopic Solutions

Netta Barzilai of Israel wins Eurovision Song Contest

Israeli singer Netta Barzilai has won the 2018 Eurovision Song Contest, the annual competition pitting singers from different countries against each other.

Read more about this at cnn.com.

Fun wasp from Kruger National Park.  

Note the expanded antennal ends (actually the other antennae snapped off).  Most likely this is one of the pollen gathering wasps in Masserinae group. 

Wasp Bling.

Here is a hyperparasite.  That is, a parasite of a parasite.  They are around, findable for those who squat down and look inside the grass and plant jungles in fields.  Just a field? You are so wrong,,, it is alive with things like this tiny Perilampid and so very very many others.  

The invitation is there....

“Why do you stay in prison, when the door is so wide open?” - Rumi

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