1

Cells, Microbes & Viruses / Re: Monkeypox: Could it be similar to cowpox, and just a mild variant of smallpox?

« on: Today at 00:41:16 »

some sort of illness doctor on this forum

In his day job, Chris (Smith) is a virologist; he has a lab with gene sequencing equipment.
- This lab was very active during the COVID pandemic
- I am sure activity will increase again if Monkeypox reaches as far as Cambridge!

See the answer from Chris, above.

2

Plant Sciences, Zoology & Evolution / Re: Have animal reactions to mirrors and windows been studied?

« on: Today at 00:37:36 »

There is a well-known "mirror test": https://en.wikipedia.org/wiki/Mirror_test
- Birds that repeatedly fly at windows are probably males attacking a perceived threat in their territory.
- I think that trying the mirror test on dolphins shows a failure of imagination by human experimenters (or lack of appreciation of the dolphin umwelt), since dolphins see their sonar reflection in any smooth surface (including the walls of a tank).

I am not so sure of visual illusions, but to some extent that also comes back to umwelt.
- For example, the mirror test did not fool my dog for very long, because dogs are strongly driven by smell.
- I'm not sure how you would construct an olfactory illusion, although I often mislead my dog on his daily puzzle hunt by leaving false scent trails...
https://en.wikipedia.org/wiki/Umwelt

3

Chemistry / Re: What properties does liquid carbon have?

« on: Today at 00:26:40 »

Another property of liquid carbon is that it will glow: At a temperature of around 5000K, it will give off white light.

You need to ensure that carbon is not exposed to oxygen as you heat it, as it will no longer be carbon...

4

Physiology & Medicine / Re: Have covid 19 vaccinations helped/hindered monkeypox?

« on: Today at 00:23:23 »

There is a sense in which a COVID vaccination or flu vaccination could counter other viruses, and it has to do with our innate immune system.
- When you are presented with a viral threat (which is what a vaccine triggers), your body sends out alert signals including Interferon, which is a non-specific signal to warn our body to prepare for a viral attack. This produces the classic cold/flu symptoms like headache, lethargy, runny nose, etc. This is why many people feel a bit off-color the day after a vaccination.
- If you were exposed to a different virus while you have this elevated interferon levels, you would be slightly protected against the second virus.
- However, this generic innate response gives way over a few days to weeks by a more targeted response with antibodies, which are specific to a particular virus
- Over a period of months to years, the antibody levels decline, but memory cells in your immune system keep watch for this specific virus, ready to ramp up activity if the same (or similar) virus is ever seen again.

So, a few weeks after a COVID vaccination, your immune system is primed for a COVID infection, but it is still on the lookout for other viruses (such as monkeypox or the common cold).
- After all, there have been outbreaks of monkeypox well before COVID-19 (or COVID-19 vaccines) were around.
- However, I would say that the relaxation of travel restrictions/quarantine requirements and limits on the size of parties after COVID has allowed (or even assisted) the rapid spread of monkeypox around the world.

As it happens, monkeypox is well-controlled by the smallpox vaccine, and vaccination is our best protection against viruses.
- Some have suggested that it was the end of smallpox vaccination in Africa which has led to reducing immunity to monkeypox in the African community, and has led to larger outbreaks (including the current one)

See: https://en.wikipedia.org/wiki/Monkeypox#Prevention

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Physics, Astronomy & Cosmology / Re: Can red/blue shifts be below galaxy arms instead of just above?

« on: Today at 00:02:21 »

I agree with Origin - the question appears to be about galaxy rotation curves.

In a spiral galaxy (like our Milky Way), most of the visible matter is in a flat disk, rotating in a certain direction, and one side will be red-shifted, and the other side blue-shifted
- It was anomalies in this galaxy rotation curve that hinted at the presence of Dark Matter
- But to see this red/blue shift due to galaxy rotation, you have to subtract the overall red or blue shift due to the whole galaxy moving towards or away from us (the relatively nearby Andromeda galaxy is moving towards us; distant galaxies are moving away from us)
- In spiral galaxies, there are globular clusters orbiting above and below the visible disk. These are thought to be remnants of smaller galaxies, and will also show an individual red or blue shift, but it's not the more organized movement of the flat disk.

There are also elliptical galaxies, which don't show the overall ordered movement of a flat spiral galaxy. These are thought to arise from the collision of two large galaxies, which disrupts the orderly motion of a spiral galaxy.

https://en.wikipedia.org/wiki/Galaxy_rotation_curve

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Cells, Microbes & Viruses / Re: Monkeypox: Could it be similar to cowpox, and just a mild variant of smallpox?

« on: 25/05/2022 11:43:30 »

Monkeypox is in the same virus family as smallpox and cowpox, and the smallpox vaccine is effective at reducing the severity of monkeypox.

The conspiracy theorists are all over this "convenient" handover from COVID to Monkeypox - and the proposed WHO treaty to extend pandemic surveillance beyond influenza to include other diseases with pandemic potential (like COVID and other zoonotic diseases).

Monkeypox is less contagious than smallpox (and much less lethal - this monkeypox strain is more like COVID, at around 2% fatality).
- But it does infect the lungs
- There are signs from the 2003 US outbreak that it did spread through aerosols from prairie dogs to humans
- The pox blisters contain viable virus, so contact with skin or clothing can cause an infection
- Unlike COVID, people are symptomatic before they are infectious, so test, track and trace with quarantine should be much more effective than with COVID (and the tracing teams will be more familiar with the process than they were in the early days of COVID!).
- Numbers are still small, and tracing is working, so we don't need to put on the masks just yet...
See: https://en.wikipedia.org/wiki/Orthopoxvirus

7

Physics, Astronomy & Cosmology / Re: Correlation vs association

« on: 24/05/2022 23:35:29 »

a is the independent variable, b is the dependent variable

I know that this is normal terminology, but it implies a causal direction.
- If there is some variable in your experiment that you can easily control, and another variable that you can easily measure, then it is fair to say that "when I changed variable x, variable y changed in a (linear/parabolic/exponential) manner"

However, when it comes to complex things like the impact of obesity in a human population on heart attacks:
- There is no easy way to control obesity in a whole population
- There is no easy way to control heart attacks in a whole population
- There are many factors which can cause heart attacks (eg genetics, congenital problems, education on exercise, stress)
- There are many factors which can cause obesity (eg genetics, income, education on healthy diet, stress)
- So the easiest thing to do is to do some sort of scatterplot of obesity vs age of first heart attack
- Then do a regression line through it, to conclude that  "with increased variable x, variable y changes in a (linear/parabolic/exponential) manner"
- You could hypothesize that obesity contributes to heart attacks (since the obesity was present before the first heart attack), but it's not guaranteed: Someone who has an underlying heart condition may be predisposed to a sedentary lifestyle, which may make them obese.
- You could make comments like "For patients with BMI > 30, a weight reduction of 1 kg is associated with a delay of z years in age of first heart attack."

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Chemistry / Re: How can I find the optimum ΔH and ΔS for passive T control?

« on: 24/05/2022 23:11:59 »

I don't get it.

Another on the sideline of practicality: It could make sense in a desert, where it gets well above 30C almost every day (including winter), and well below 15C almost every night (even in summer).

You would need two tubs of your phase change material which can be selectively exposed to outside air or inside air.
- During the day, you expose one tub to the outside air to heat it, while the other (cold) tub is exposed to inside air to keep the house cool.
- Reverse it overnight: Expose the hot tub to the inside to heat the house, while the other tub is exposed to the outside air to cool it, ready for the next day.

Effectively, you want a system that will produce a 12-hour phase change* in the outside temperature cycle.
     * This is a temporal phase change, achieved by a physical phase change

For it to work well, your house would need to be well-insulated, and you would need fans to circulate air past the tubs of hot/cold materials.

9

New Theories / Re: Is this why Ivermectin appeared to be the answer to Covid?

« on: 24/05/2022 22:51:56 »

We recently had a national election in Australia, and party had a policy that included permission to use ivermectin for COVID (among other things). In my state, they received 0.03% of the vote...

The figurehead of another party imported $1M of ivermectin. He had to destroy it, as ivermectin can only be distributed by doctors, for proven conditions like intestinal parasites. They got 0.25% of the votes.

My guess is that almost half of the US population would approve of ivermectin.

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Radio Show & Podcast Feedback / Re: Feedback on: Question Of The Week in Podcast vs Forum

« on: 24/05/2022 22:24:09 »

QOTW is a question, and the Forum is about answering questions, so it's still worthwhile posting QOTW on the forum.

Often the discussion on the forum will take a different approach than the expert (or multiple different approaches).

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That CAN'T be true! / Re: How do people survive lightning strikes?

« on: 24/05/2022 10:15:57 »

I can think of a couple of critical organs between the legs that might be in the path of the lightening

If the Earth Potential Rise is (say) 30,000 Volts, and it dissipates over a distance of (say) 100m, that is 300 Volts per meter in the soil.

A typical pace might be 0.5m, so 150 Volts between the legs will produce an electric shock, but not anything like the voltage of a direct lightning strike.
- The ground resistance will also provide some series impedance to the current in the legs
- If you are standing, the distance between your feet might be closer to 0.2m
- If you are walking, half of the time, there will be only 1 foot on the ground (ie perhaps a small current in one foot, but nothing up the legs - and that one foot may have a plastic-soled shoe on it)
- If you are running, most of the time there will be only 1 foot on the ground

The human condition is much better than for (say) a cow. The distance between front and rear feet is more like a meter (300V in the above scenario), and there are some very electric-sensitive organs between these locations, like the heart and spinal cord.
- Most of the time, cows have at least 2 feet on the ground, and no shoes

12

Radio Show & Podcast Feedback / Re: Feedback on: Question Of The Week in Podcast vs Forum

« on: 24/05/2022 00:29:35 »

It would be good if the podcast team could remember to put an entry in the "QOTW" forum around the time the question is asked on the podcast.
- Then we could pontificate until the nominated expert provides the "official" answer.
- At one time, the podcast team sometimes mentioned some of the ideas on the forum, as well as playing the response from the expert...

13

That CAN'T be true! / Re: How do people survive lightning strikes?

« on: 23/05/2022 11:18:14 »

how can a human body tolerate that amount of heat?

The human body is largely composed of water, which has a very high heat capacity.

The water is slightly salty, which makes it slightly conductive
- Probably slightly more conductive than a tree-trunk, so don't lean on a tree trunk in a storm!
- But the voltage drop across 2 meters of ionised air is very low, so some of the energy may bypass the human body (at least, in survivors)

even if only for a nanosecond?

Standard lightning test waveforms have a rise time of 1μs, and a fall time of 50μs.
So you could loosely say that the average duration of a lightning impulse is around 50μs, or 1/20,000 of a second.

14

Physics, Astronomy & Cosmology / Re: How can I pass a large DC current through mercury?

« on: 23/05/2022 11:05:05 »

Ampere longitudinal forces in conductor

This video shows a fountain created by passing electricity through an alloy of Sodium and Potassium (NaK).
It is a demonstrator for the type of coolant planned for some Fast Breeder reactors.

As I recall, they point out that the success of this fountain is largely due to the low density of NaK. If you tried to do it with Mercury, the high density of Mercury would make for a rather disappointing display.

PS: NaK should not be kept in your home. It reacts with moisture or oxygen in the air, and most other things with which it comes into contact, including humans...

15

General Science / Re: How do we make synthetic gasoline?

« on: 22/05/2022 22:49:40 »

Methanol

In Brazil, they make engines that can take up to 100% ethanol, and automatically adjust to the mixture.
My car says that it can use up to 10% Ethanol.

The problem is that plastic fittings can be damaged by organic solvents like ethanol and methanol.
So buy a car from Brazil before you try this at home, and don't use Methanol (there are tax reasons for a small amount of Methanol).
https://en.wikipedia.org/wiki/Ethanol_fuel_in_Brazil

16

Physics, Astronomy & Cosmology / Re: How can I pass a large DC current through mercury?

« on: 22/05/2022 22:42:59 »

If you want to put a lot of current through metal (such as happens during aluminium smelting, for example), you use a low voltage, much lower than 5 Volts - and very thick wires.
https://en.wikipedia.org/wiki/Hall%E2%80%93H%C3%A9roult_process

Note that mercury is volatile, and the invisible fumes are toxic, so you should not have mercury in your home (except, perhaps, sealed in an old-fashioned thermometer); in the lab, it should be kept in a fume cupboard when uncapped.

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That CAN'T be true! / Re: How do people survive lightning strikes?

« on: 22/05/2022 01:17:17 »

Most people who are impacted by lightning suffer due to Earth Potential Rise, which affects a radius of many meters around the lightning strike.
- This causes a high voltage between the feet, which causes a current up one leg, and down the other - avoiding major critical organs.
- The affected people can be seemingly hit at random - if both feet are equidistant from the strike, there will be no potential difference.

There is something called the "skin effect" in wires, where high-frequency components tend to stay in the outer skin of the wire.
- In the rarer case where a person is directly hit by lightning, "skin effect" takes on a dual meaning - with waveform time constants around 10μs-50μs, there are a lot of high-frequency components, and much of the current tends to flow around the skin rather than the core.

However, even in the survivors, long-term neurological problems often occur, as well as short-term problems like damaged eardrums and burns also occur.

https://en.wikipedia.org/wiki/Lightning_strike#Strikes

18

Just Chat! / Re: a suitable pseudonym

« on: 22/05/2022 01:03:17 »

I've never met a scientist who I would call remotely autistic.

Until around the 1980s (perhaps, until the release of Rainman, in 1988), autism was commonly seen as a development problem of infants, who were often locked up in institutions. Since virtually all scientists are adults, they could not be autistic, by definition.

Now it is recognised as:
- occurring in adults too (usually children who grew up outside an institution, and learned to adapt)
- occurring in a spectrum, from very mild to very severe
- more severe cases often being seen as children of parents with mildly autistic tendencies (ie a strong genetic contribution) - with Silicon Valley being a particularly intense hotspot

We can now look back and see scientists who were almost certainly autistic, eg
- Cavendish, who was brilliant, but could never talk directly to people, but used correspondence.
- Mendel, who spent years breeding peas
- Darwin, with his intense childhood focus on collecting bugs
- Even many of the early researchers into childhood autism! (in one case, because they had an autistic child themselves)
- It is that often-introverted focus on collecting information in some specific area, often with a numeric focus that means someone with autistic tendencies is more likely to become a scientist, engineer, musician or perhaps an artist (in contrast to movie star or a socialite, for example).
- A text-based forum like this one is likely to attract people with some of these characteristics...

https://en.wikipedia.org/wiki/Autism_spectrum

You spend your whole life trying to find something you enjoy, and then everyone tells you to shut up about it.

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Physics, Astronomy & Cosmology / Re: What happens when photons leave the sun?

« on: 19/05/2022 00:39:01 »

how much Doppler shift is there?

Each year, around 3-4th January (perihelion, closest to the Sun) and 3-4th July (aphelion, farthest from the Sun), the Earth is neither moving towards or away from the Sun, and there is no Doppler shift. Around October there is a maximum Doppler blue shift (Earth moving towards the Sun) and around May there is a maximum Doppler red shift (Earth moving away from the Sun).

As others have pointed out, all year long there is a gravitational red shift (or "Einstein shift"), as photons "climb out" of the Sun's gravitational well. Depending on your frame of reference, you could say some of the following things:
- Photons don't lose speed as they always travel at c
- Photons don't lose kinetic energy, since the photon is massless
- Photons do lose momentum
- The photon frequency does decrease

One way of looking at this frequency decrease is to consider Einstein's time dilation.
- Deep in a gravitational well (eg the surface of the Sun), time moves more slowly, compared to an observer on the surface of the Earth
- So a Hydrogen atom emitting a spectral line on the surface of the Sun will do so more slowly than a Hydrogen atom emitting the same spectral line on the surface of the Earth
- So when you compare the frequency of the light from the Sun with the frequency of light generated here on Earth, you will find the light from the Sun has a lower frequency.

Einstein shift will be a maximum at aphelion, and minimum at perihelion.

photons are on their 1,000,000 year journey out of our sun

Under the extreme conditions of a supernova, energy from the core of a star can reach the surface much more quickly - just hours.

But neutrinos don't interact much with matter; traveling at (pretty much) the speed of light, they can reach the surface of the star in just seconds.
- To date, such a "race" has only been observed once, when a supernova occurred in the nearby Large Magellanic Cloud (a dwarf galaxy orbiting our Milky Way galaxy).

https://en.wikipedia.org/wiki/SN_1987A#Neutrino_emissions

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Chemistry / Re: What colour is paint before the colour is added?

« on: 19/05/2022 00:10:29 »

'White' paint is a base with a bright white pigment, probably titanium dioxide, added.

Before titanium dioxide, lead oxide was often used as the base. Lead is a neurotoxin, and children sometimes picked up lead from flaking paint, or even lead paint on kid's toys. Thankfully, lead paint (and leaded petrol) is now banned.

Even farther back in time, lead oxide was used in makeup.

There have also been cases where arsenic was used as a green tint...