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  #2101  
Old 28.01.2021, 14:23
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Re: Ask a Scientist

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I have 2 powerful PCs with 1000W power supply and multiple GPUs, powerful CPUs, multiple HDs etc. My yearly electricity bill is around CHF850.

My PCs are left ON 24/7. If I switch them off at night, how much money could I potentially save on my electricity bill? Just an educated guess?
Educated guess, what are we? Barbarians? A powermeter answers better than anyone https://www.galaxus.ch/de/s4/product...B&gclsrc=aw.ds

Less of a joke, I doubt the computers reach 50% of annual demand. What's your guess?
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  #2102  
Old 28.01.2021, 14:44
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Re: Ask a Scientist

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Educated guess, what are we? Barbarians? A powermeter answers better than anyone https://www.galaxus.ch/de/s4/product...B&gclsrc=aw.ds
The aim was to save money, not buy more stuff, but I might get it in the name of science

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Less of a joke, I doubt the computers reach 50% of annual demand. What's your guess?
My barbarian guess would be a saving of CHF100 if I switch the PCs off?
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  #2103  
Old 29.01.2021, 13:15
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Re: Ask a Scientist

Given a continuous, differentiable curve, find the mid point and radius of a circle that bisects the x-axis and is tangential to the curve at a specific point on the curve.

It looks something like the blue circle in this diagram. These are Mohr's circles.



We know the point where the circle touches the curve, we know the gradient at that point, we know that the circle must be perpendicular to the x axis at y = 0. I think that's sufficient information. But how to calculate it? Geometrically or, more interesting, analytically?

(For the actual work, the students were told that trial and error was acceptable - but I'm interested in how to solve it exactly.
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Last edited by NotAllThere; 29.01.2021 at 17:10. Reason: Marton pointing out my error.
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  #2104  
Old 29.01.2021, 15:28
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Re: Ask a Scientist

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Given a continuous, differentiable curve, find the mid point and radius of a circle that bisects the y-axis and is tangential to the curve at a specific point on the curve.

It looks something like the blue circle in this diagram. These are Mohr's circles.



We know the point where the circle touches the curve, we know the gradient at that point, we know that the circle must be perpendicular to the x axis at y = 0. I think that's sufficient information. But how to calculate it? Geometrically or, more interesting, analytically?

(For the actual work, the students were told that trial and error was acceptable - but I'm interested in how to solve it exactly.
Surely that blue circle is bisected by the x axis?
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  #2105  
Old 29.01.2021, 17:10
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Re: Ask a Scientist

Yes. Corrected now. Thanks. I originally wrote "bisected at y=0" but didn't edit properly.
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  #2106  
Old 29.01.2021, 19:30
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Re: Ask a Scientist

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...it is impossible to be perfect symmetrically, if we will be, then will get in the resonance which theoretically will make as immortals...as you now mathematically everything is imperfect around us, to prevent us get in the state of resonance...then we live on n-harmonics of the universe at the moment, if to believe in Bing-Bang we are now in the last descending harmonics, after which everything will disappear in nothing and will explode after in another Bing-Bang...
I know physicists and math folks are dealing with symmetries and dig in Big Bang big time. But I was thinking about symmetry in natural world, the restrictions and reasons for them, the theories that will interfere. Found my stuff a while back, just waited to have time for this lovely distraction. Gábor Holló hit my spot and not only how it reads in his "Demystification of animal symmetry: symmetry is a response to mechanical forces".

This VTech stuff is great too, drier but an awesome exercise if anyone has a lil time left this ugly rainy weekend, google "Symmetry and Causation: A General Theory of Biological Individuality" by Benjamin Jantzen.

Applied theories are always more fun.
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  #2107  
Old 29.01.2021, 19:35
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Re: Ask a Scientist

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Yes. Corrected now. Thanks. I originally wrote "bisected at y=0" but didn't edit properly.
Think about Pythagoras
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  #2108  
Old 19.02.2021, 15:39
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Re: Ask a Scientist

Is everyone's sense of taste and smell exactly the same? For example, my other half absolutely loathes the taste and smell of coriander and can detect its presence in small concentrations in cooking. She's not the only one - I've encountered a few people that don't like coriander. From my part, I despise marzipan - it just smells wrong, and I'm puzzled as to how people can enjoy eating it. I've heard talk of poison avoidance responses and people's reactions being potentially due to their body thinking that they are eating something that could be poisonous. Is there any truth to that?

In a not unrelated vein, how do some artificial flavours like cherry (for example Dr Pepper) and banana smell absolutely nothing like the original article?
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  #2109  
Old 19.02.2021, 16:09
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Re: Ask a Scientist

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Is everyone's sense of taste and smell exactly the same? For example, my other half absolutely loathes the taste and smell of coriander and can detect its presence in small concentrations in cooking. She's not the only one - I've encountered a few people that don't like coriander. From my part, I despise marzipan - it just smells wrong, and I'm puzzled as to how people can enjoy eating it. I've heard talk of poison avoidance responses and people's reactions being potentially due to their body thinking that they are eating something that could be poisonous. Is there any truth to that?

In a not unrelated vein, how do some artificial flavours like cherry (for example Dr Pepper) and banana smell absolutely nothing like the original article?
https://www.independent.co.uk/news/s...n-2192370.html
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  #2110  
Old 19.02.2021, 16:17
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Re: Ask a Scientist

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Is everyone's sense of taste and smell exactly the same?
Almost certainly not - there are many flavours that some individuals can detect but others cannot. But it's confused by whether or not they're flavours you _like_, so one person's sensitivity to a particular flavour may, or may not, be due to them being more able to detect it.

There are some definitions out there, for example so-called 'supertasters' who have much more granularity and sensitivity, and there's some evidence of a correlation between them and their dislike of certain flavours. I may fall into that category, and am very averse to bitter flavours, which may be because for me they're much stronger than for others.

It's all very subjective though, only very specific aspects of it are measurable.

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For example, my other half absolutely loathes the taste and smell of coriander and can detect its presence in small concentrations in cooking
That's where things get more confusing. I can detect small amounts of it too, but unlike the bitter taste I previously mentioned it's not unpleasant to me.

I know a few people who are very sensitive to a "fishy" flavour, which I can never accurately detect or describe, e.g. my wife, who will happily eat tinned tuna, which is about as fishy as it gets to me, but is completely unable to stomach most other fish.

How much of these likes or dislikes stem from exposure and upbringing is unclear, but there is certainly a connection - you won't find many desert-island dwellers who dislike fish, for example.

But, it has to be said, anyone who doesn't like coriander is a heathen.

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  #2111  
Old 19.02.2021, 16:19
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Re: Ask a Scientist

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Given a continuous, differentiable curve, find the mid point and radius of a circle that bisects the x-axis and is tangential to the curve at a specific point on the curve.

It looks something like the blue circle in this diagram. These are Mohr's circles.



We know the point where the circle touches the curve, we know the gradient at that point, we know that the circle must be perpendicular to the x axis at y = 0. I think that's sufficient information. But how to calculate it? Geometrically or, more interesting, analytically?

(For the actual work, the students were told that trial and error was acceptable - but I'm interested in how to solve it exactly.
If the curve can be differentiated at any given point, you can obtain the gradient at the given point and thence the formula of the straight line that is perpendicular to it that point. Then you calculate where that line intersects the x-axis. And the rest should be simple. No?
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  #2112  
Old 19.02.2021, 16:43
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Re: Ask a Scientist

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If the curve can be differentiated at any given point, you can obtain the gradient at the given point and thence the formula of the straight line that is perpendicular to it that point. Then you calculate where that line intersects the x-axis. And the rest should be simple. No?
In other words, suppose the differentiable curve is y=f(x) and the point of intersection is (x0, f(x0))

The gradient the point of intersection is f'(x0)
The line perpendicular at that point is

y = f(x0) - (x-x0)/f'(x0)

resolving x for y=0 gives

x = f(x0)f'(x0)+x0

if I haven't slipped up somewhere


Bonus assignment: calculate it using vectors rather than coordinates. It's actually even simpler that way.
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  #2113  
Old 19.02.2021, 16:48
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Re: Ask a Scientist

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I have 2 powerful PCs with 1000W power supply and multiple GPUs, powerful CPUs, multiple HDs etc. My yearly electricity bill is around CHF850.

My PCs are left ON 24/7. If I switch them off at night, how much money could I potentially save on my electricity bill? Just an educated guess?
Too many unknowns in the equation, but you can easily find them on the bill: either your total consumption in kWh per year (easier) or, alternatively, the price you pay per kWh.

1000 W=1 kW. So one kWh every hour. There are 24x365 h to a year. That‘s 8760 kWh a year. (Assuming both PCs together use 1000 W. If each of them does, it’s double.)

So if you switched them off for half the time, that’d mean a reduction by roughly one half of those 8000+ kWh (or 17000+ if it‘s 1000 W per PC). You can calculate the savings by calculating the proportion of your total consumption.

Even if it‘s 8000 rather than 17000 kWh, the number strikes me as almost unbelievably high, seeing that an average household of four Swiss persons has an annual electricity consumption of 4000 kWh - in total, not just for PCs. So 1000 kWh per capita. (We use less per capita but I‘m into saving energy.) Did we get all our numbers straight?
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  #2114  
Old 19.02.2021, 18:18
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Re: Ask a Scientist

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Is everyone's sense of taste and smell exactly the same? For example, my other half absolutely loathes the taste and smell of coriander and can detect its presence in small concentrations in cooking. She's not the only one - I've encountered a few people that don't like coriander. From my part, I despise marzipan - it just smells wrong, and I'm puzzled as to how people can enjoy eating it. I've heard talk of poison avoidance responses and people's reactions being potentially due to their body thinking that they are eating something that could be poisonous. Is there any truth to that?

In a not unrelated vein, how do some artificial flavours like cherry (for example Dr Pepper) and banana smell absolutely nothing like the original article?
Genes and diseases are the explanations to your question.

https://www.europeanreview.org/wp/wp.../1305-1321.pdf
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  #2115  
Old 19.02.2021, 18:51
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Re: Ask a Scientist

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It's all very subjective though, only very specific aspects of it are measurable.
...
How much of these likes or dislikes stem from exposure and upbringing is unclear, but there is certainly a connection - you won't find many desert-island dwellers who dislike fish, for example.
Yes. Also expectation. I once participated in an experiment about visual stimulation of gustatory expectation and texture and flavour of foods. As the reason to mask the experiment, we were told that the purpose was to collect descriptive vocabulary about food.

First, we were shown known foods, behind glass, at a distance so that we could not and did not expect to be able to smell them. All the subjects waited in one room, while one subject was called in to the food room, to sample each of those foods and describe the taste. Once one had participated, one was to go and sit in the darkened part of the room, in absolute silence, to watch each next participant.

Well, that was a surprise! The foods had been recreated with fantastic attention to detail to look like something one would know and expect, but they were, in fact, made of completely different substances. For example, what looked like guacamole was made of peas, what looked like spaghetti bolognese did contain spaghetti but was made of chocolate, what looked like a nutty, granola chocolate cake was made of beef mince-meat, what looked like a mayonniase dip to go with salty crackers was made of banana and cream, what looked like a strawberry milkshake was made of beetroot, and so on. The switches were especially across the line of salty and sweet.

The reactions were very, very funny. As soon as I took a bite, I spat the food out. The contradiction between anticipated flavour and the real taste and texture was so unexpected that my system rebelled and behaved as if the food were rotten. There were about 30 or 40 of us, and almost everyone spat out the food, or gagged, irresistably. This was so even after trying the third or fourth item, i.e. once one had understood that the foods were distorted. The very few who managed to swallow that single bite, later said it had taken huge self-control, motivated mainly by not wanting to appear rude to the testers.

There was a control group who were blindfolded. They were not told what they were going to be tasting, and found all the foods tasty, acceptable or tolerable, identifying them more or less correctly (except for the beetroot milkshake).
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  #2116  
Old 19.02.2021, 19:11
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Re: Ask a Scientist

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In a not unrelated vein, how do some artificial flavours like cherry (for example Dr Pepper) and banana smell absolutely nothing like the original article?
The main answer to this is simple: money. Food manufacturers are so stingy that they often won't pay for decent flavors. Firmenich, where I worked, had wonderful, authentic versions of every flavor under the sun.

However there are other factors. Depending on the product, it may be difficult to make a stable flavor that tastes authentic. For instance, if it is very acid, the environment will break down the more chemically fragile molecules. A need for a long shelf life can eliminate some of the best molecules for the same reason.
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  #2117  
Old 19.02.2021, 20:00
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Re: Ask a Scientist

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Is everyone's sense of taste and smell exactly the same?
Sometimes and for some people.

I love marzipan and cilantro.

Another chemical flavor aside of fake bananas and cherry is fake grape flavor, yum.

I don't know anyone who wouldn't like bubblegum flavor, despite the fakeness it appeals universally.
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  #2118  
Old 19.02.2021, 23:18
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Re: Ask a Scientist

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Too many unknowns in the equation, but you can easily find them on the bill: either your total consumption in kWh per year (easier) or, alternatively, the price you pay per kWh. (...)

Even if it‘s 8000 rather than 17000 kWh, the number strikes me as almost unbelievably high, seeing that an average household of four Swiss persons has an annual electricity consumption of 4000 kWh - in total, not just for PCs. So 1000 kWh per capita. (We use less per capita but I‘m into saving energy.) Did we get all our numbers straight?
PS Why on earth not turn those powerful computers off anyway? Complete no-brainer IMHO. Like most of us, I was brought up to switch off the light when leaving a room. We waste far too much energy because it‘s too cheap. It may not cost much money, but that doesn‘t mean we can afford to go on doing it. Money is the currency of mere humans. Energy is the currency of nature. If we saved more of it, we could avoid the projected demand for a gas-fired power plant. Which would be worth while because such a plant would generate carbon dioxide*, import gas from the likes of Putin and Co. and, in case it‘s still not obvious, cost a lot of money.

(* This is, after all, the science forum. Hopefully no need to go into the climate skepticism thing.)
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Old 28.02.2021, 17:38
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Re: Ask a Scientist

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I know physicists and math folks are dealing with symmetries and dig in Big Bang big time. But I was thinking about symmetry in natural world, the restrictions and reasons for them, the theories that will interfere. Found my stuff a while back, just waited to have time for this lovely distraction. Gábor Holló hit my spot and not only how it reads in his "Demystification of animal symmetry: symmetry is a response to mechanical forces".

This VTech stuff is great too, drier but an awesome exercise if anyone has a lil time left this ugly rainy weekend, google "Symmetry and Causation: A General Theory of Biological Individuality" by Benjamin Jantzen.

Applied theories are always more fun.
…look where we are now with cloning after three decades...nowhere...nothing symmetrical can exist...theoretically in maths yes, but not in nature...as every second is different...
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  #2120  
Old 28.02.2021, 17:52
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Re: Ask a Scientist

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…look where we are now with cloning after three decades...nowhere...nothing symmetrical can exist...theoretically in maths yes, but not in nature...as every second is different...
UAE camel cloning became an industry worth millions of dirhams.
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