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Physiology & Medicine / Re: Should I accept any covid-19 vaccine offered

« on: 29/06/2021 10:55:07 »

The UK will actually run a clinical trial to test the efficacy of combining AstraZeneca and Pfizer vaccines

I saw the results on the news tonight...

AZ followed by Pfizer induced higher antibodies and T cell responses than Pfizer followed by AZ
Both of these mixes induced higher antibodies than two doses of AZ
The highest antibody response was seen after two doses of Pfizer, and the highest T cell response from AZ followed by Pfizer

See: https://www.bbc.com/news/health-57636356

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Plant Sciences, Zoology & Evolution / Re: How can I keep my grass short?

« on: 31/05/2021 18:32:22 »

The south side of my lawn started sprouting moss after the neighbour put up a six foot fence blocking most of the sunlight. After a few years it's now a thick carpet of moss with a few sparse wisps of grass poking through it.

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That CAN'T be true! / Re: Why are atheists despised and ridiculed?

« on: 16/05/2021 21:21:48 »

So, it turns out that spammers are despicable and ridiculous.
Gosh!

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Chemistry / Re: What would you want to see done with NaK?

« on: 27/04/2021 07:42:34 »

I've seen a video of mercury dissolving gold, so it would be interesting to see what metals would dissolve in NaK.

Watching how the reaction of NaK with alcohols changes as the number of carbons increase could be interesting. I suspect longer chain alcohols react more slowly than short chain alcohols.

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COVID-19 / Re: Could COVID-19 cause Psychological problems?

« on: 25/04/2021 04:36:48 »

Loss of smell is one of the peculiar symptoms of COVID-19 infection
- The sense of smell has a direct connection into the brain, and affects us at an emotional level - not just in food, but in social interactions and familiar places
- Loss of smell can result in eating disorders and depression.
- Even worse, in some people, the sense of smell eventually comes back, but is rewired differently, so favorite foods are now revolting. This would be rather distressing.

Clotting problems are associated with COVID-19 infection in some people, affecting the capillaries. Clotting in the brain could provoke a range of psychological problems.

Perhaps 10% of people with COVID infection get "Long COVID", a post-viral syndrome affecting many normal functions
- Many of the symptoms include loss of memory, fuzzy thinking, etc
- This may be an auto-immune problem, or maybe a disruption of the autonomic nervous system?
- Symptoms sometimes last for months - there are now cases that have persisted for a year
- A study suggests that only 40% recover after 3 months of intensive rehabilitation.
- This has resulted in loss of work in many cases.
- Many doctors see this as a psychosomatic problem.

Anecdotes that long-haul COVID symptoms that dissipated after COVID vaccination suggests that perhaps the immune system may be involved.

Listen (37 minutes); https://www.sciencefriday.com/segments/covid-long-haulers/

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Technology / Re: Why are solar panels not curved?

« on: 01/05/2020 23:38:56 »

the top of the solar panel is receiving the full sunlight, and as the sun sets on the horizon, it's beams are  landing on the other side of the "tunnel"?"

Each solar cell produces very little voltage - around 0.7V.
- Very many cells are placed in series so that they add up to around 900V DC for input to the inverter (this electronic circuit converts DC into AC).
- A solar cell that is in the dark does not put out a voltage, but acts as a resistance to the flow of electricity (reduces the voltage)
- So if you have half the cells in the dark, you would get less output than if you just had half of the cells.

You want all cells in the solar panel to be similarly illuminated, so they put out a similar voltage, have a similarly low resistance, and the inverter can efficiently convert the total DC voltage (whatever it adds up to) into AC.

Why are solar panels not made in a tunnel shape

There are some solar collectors that are built in a trench shape, with a parabolic cross-section.
- These collectors have a pipe which runs down the focus of the parabola, so the Sun's rays are collected from a wide area and are focused on the thin thermal collector in the middle of the trench
- Something like oil or water runs through the pipe, collecting the heat
- The disadvantage of this type of collector is that they are mechanically more complicated - a motor has to follow the Sun across the sky; if the motor (or the Sun-following sensor) breaks down, it only collects sunlight for perhaps 30 minutes of each day
- In larger solar farms, motors keep the flat solar cells pointed at the Sun; at least, in this case, if the motor breaks down, the flat solar panel will still collect power for several hours of the day, even if it is pointing in the wrong direction.
- The advantage of flat, stationary solar cells is that they are mechanically simple; on cloudy days, the sunlight comes from all directions across the sky, and flat panels can collect solar energy from across the sky

See: https://en.wikipedia.org/wiki/Solar_power#Concentrated_solar_power