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  #621  
Old 16.04.2008, 13:51
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Re: Ask a Scientist

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Any biochemists or similar here? I've read in today's newspaper that antibiotics in the waste water are a problem. It wasn't mentioned though if the cause are properly used medicaments, or if people flush unwanted pills down the toilet instead of bringing them back to the pharmacy. What outstanding properties have the molecules of antibiotics, I wonder?
It is a problem actually. Many things that we as humans ingest on a daily basis, birth control pills, analgesics, antibiotics etc. are not metabolized by our bodies so are excreted out through urine. This goes into the waste treatment plants where the water is treated but the molecules of the aforementioned are not removed or degraded etc.

Now imagine that all these antibiotics are gradually making their way to the sea, where we have the red tide phenomenon, (or huge algeal blooms) which consume all the oxygen and nutrients until they die which increases the number of bacteria A LOT. Now, we have tons and tons of bacteria reproducing to their little hearts content in the presence of antibiotics, allowing them to build up resistance to them. Which could completely make our current antibiotic regime completely null and void. Now tell me that isn't a problem.

We do not want antibiotics getting in the presence of bacteria unless we know that all of the bacteria will be wiped out. You don't wipe them all out, bacteria mutate, become antibiotic resistant.
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  #622  
Old 16.04.2008, 14:30
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Re: Ask a Scientist

Yup sounds like a problem... I was confused because I assumed that medicaments work because they are very reactive, which doesn't seem to be a requirement.
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  #623  
Old 16.04.2008, 14:50
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Re: Ask a Scientist

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If I am rectangle, then the amout of water I will get hit by is rectangle x water x time (till I get out of the rain.)
rectangle and water are the same the only change is the time..ie if I run or walk?
The correct answer is more complicated and involves the rain flux, angle of incidence, relavite direction/velocities of wind and walker/runner etc. After starting to ponder this I was relieved that someone has done the job properly and created a rain flux wetnessometer, read intro here
http://www.dctech.com/physics/features/0500.php
and play with numbers here
http://www.dctech.com/physics/features/0600.php

My numbers indicate that the total water content that impacts on my body is less if I run, but there's still the argument that once you're wet, you're wet, (assuming that the human body and clothes aren't the mythical ideal sponge that we would get in a physics lecture), so minimizing the surface that is actually absorbing the water is beneficial.

Either way - the moral of the story is to carry an umbrella!

Last edited by Lorenheim; 16.04.2008 at 14:51. Reason: added GIF
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  #624  
Old 16.04.2008, 14:59
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Re: Ask a Scientist

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Yup sounds like a problem... I was confused because I assumed that medicaments work because they are very reactive, which doesn't seem to be a requirement.
That's actually really a very common misconception. How antibiotics actually work is that they shut down the synthesis of certain key compounds that bacteria need to survive. So basically, what the antibiotic does is go into the 'active site' of a protein, kind of like a lock and key fit (protein being the lock, antibiotic being the key, well a key that gets stuck). The molecules that need to go in there for the bacteria to survive can't because there's already something in there (something that doesn't want to leave). However, if the bacteria mutates and the protein (lock) is no longer exactly the same (but still viable) the antibiotic 'the key' no longer fits snugly into the lock and the bacteria can again make what it needed to to survive.

Which is why it is a good thing that our bodies don't metabolize the antibiotics, or else they'd never make it to the bacteria to do their job, but a bad thing because they are now making it out into the environment.

EDIT: That's actually how a lot of drugs work, they stop something from being made by a protein. Understanding the fundamental intermolecular interactions that make the "key" fit the "lock" is a huge portion of the research that my lab does.
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  #625  
Old 16.04.2008, 15:31
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Re: Ask a Scientist

Is anyone else starting to a 6-dimension pants expansion listening to all this science.... fantastic stuff!
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  #626  
Old 16.04.2008, 15:50
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Re: Ask a Scientist

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My numbers indicate that the total water content that impacts on my body is less if I run,
In general and in reality without all the 1st year idealisations, because you spend less time in the rain. Nothing to do with all the other complicated factors.

The interesting question is if the rate of water impact is less if you run for various angles of rain. One should be able to answer this without resorting to equations. Sounds like a good PhD defense question.
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  #627  
Old 16.04.2008, 15:59
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Re: Ask a Scientist

Not that simple. Rain landing on the small cross section of your head, vs the rain that is incident on (primarily) the front of your body as you move.

Assuming its not windy, if you run you force your body to impact far more water on the front of your body instead of it falling on your head in true Fred Astaire stylee and deflecting.

dave




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In general and in reality without all the 1st year idealisations, because you spend less time in the rain. Nothing to do with all the other complicated factors.

The interesting question is if the rate of water impact is less if you run for various angles of rain. One should be able to answer this without resorting to equations. Sounds like a good PhD defense question.
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  #628  
Old 16.04.2008, 16:12
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Re: Ask a Scientist

Well, on the one hand, No, that is why I specifically said no idealisations. What you refer to only works if rain fails exactly down and your feet, back, and beer belly don't stick out farther than your head and that rain hitting your head magically evaporates without dripping down your face and then body, and there is absolutely still air around your body. I could go one forever. The heavier the rain, the more this point becomes valid.

But let's take your point of view, Dave, and the ideal 1st year physics problem. If you stand around, even with the smaller surface area of your head, since you will be standing outside for the whole duration of the rain and let's take an average rainfall of 6 hours, you do the math, and you will see that way more rain hits you, no matter how fat your beer belly is, than if you run for 10 minutes to the nearest dry escape. That was my point if you missed it. For short rainfalls, it becomes an optimisation problem that geeks like me get degrees on.

In the case of the latter, this is why I said rate is a more interesting question to ask, and then your points become more valid.

Back to my Laplace transforms of epidemic branching processes.

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Not that simple. Rain landing on the small cross section of your head, vs the rain that is incident on (primarily) the front of your body as you move.

Assuming its not windy, if you run you force your body to impact far more water on the front of your body instead of it falling on your head in true Fred Astaire stylee and deflecting.

dave

Last edited by HashBrown; 16.04.2008 at 16:41.
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  #629  
Old 16.04.2008, 16:12
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Re: Ask a Scientist

Isn't this an option in brewingsoftware like ProMash and so on? I remember reading about one of those programs where you could upload your local water signature and compare it with, say, water form Burton. It would then show what to add and in which quantities per liter.

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There seems to be plenty of info on the microorganism content but not on what I want (specifically for most areas of SG and ZH.

Now, as a student, I'm sure you'll see this as an irresistable challenge .

In particular, I would like typical concentrations of:

Ca
Mg
Na
SO4
HCO3
Cl


I would also like to know what would typically be the effect of adding 1 g/litre of the following into the equation:

CaSO4
NaCl
MgSO4
CaCl
NaHCO3
CaCO3

And those on the ball will be thinking I'm trying to Burtonise some water (very important in producing Pale Ales )

Could be free beers on the cards for the answers.....
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  #630  
Old 17.04.2008, 09:46
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Re: Ask a Scientist

About the rain:

The correct answer of the question is that for any type of rain (density of drops, angle) there is an exact speed you should go to get the minimum amount of water. It is just another problem of optimization. you can suppose a simple rectangular cube as a person or you can complicate the problem as much as you wanted, but the solution is up there.
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  #631  
Old 17.04.2008, 10:03
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Re: Ask a Scientist

I think I had this hidden in all my Dave poking.

But my point was the TOTAL WETNESS optimisation depends on the the very important condition where your escape from rain point is. The above solution only considers the RATE of getting wet. These are two different optimisations, the latter being of more practical consideration, and a more interesting problem mathematically (non-linear).

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About the rain:

The correct answer of the question is that for any type of rain (density of drops, angle) there is an exact speed you should go to get the minimum amount of water. It is just another problem of optimization. you can suppose a simple rectangular cube as a person or you can complicate the problem as much as you wanted, but the solution is up there.

Last edited by HashBrown; 17.04.2008 at 19:15.
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  #632  
Old 17.04.2008, 10:23
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Re: Ask a Scientist

I did actually post a response, but I deleted it as I have more important technical points to discuss, and it ain't worf it.

I suggest you complete a repeatable series of experiments, say over the next two months. We will be on standby with the Lemsip.

dave

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I think I had this hidden in all my Dave poking.

But my point was the TOTAL WETNESS optimisation depends on the the very important condition where your escape from rain point is. The above solution only considers the RATE of getting wet. These are two different optimisations, the latter being of more practical consideration, and a more interesting problem mathematically.
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  #633  
Old 17.04.2008, 10:32
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Re: Ask a Scientist

I brought a shower, fan, and trolley to the Talacker last night for us to experiment with.
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  #634  
Old 17.04.2008, 19:10
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Re: Ask a Scientist

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About the rain:

The correct answer of the question is that for any type of rain (density of drops, angle) there is an exact speed you should go to get the minimum amount of water. It is just another problem of optimization. you can suppose a simple rectangular cube as a person or you can complicate the problem as much as you wanted, but the solution is up there.
Now that's what I call a proper answer! All we need is the relevant equation and a reference to the scientific literature and we can close the subject.

Mind you I think "just another problem of optimization" is a bit cheeky. Some optimization problems are VERY hard and some can be proven to be totally impossible.
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  #635  
Old 22.04.2008, 22:42
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Re: Ask a Scientist

Hi I would really like to know why you I never get electric shocks in the rain? I frequently get a shock when locking my car, but never when it rain. Is it anything to do with the transfer of hydrogen ions from the water equallizing the imbalance of ions about your person?
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  #636  
Old 22.04.2008, 22:45
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Re: Ask a Scientist

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Hi I would really like to know why you I never get electric shocks in the rain? I frequently get a shock when locking my car, but never when it rain. Is it anything to do with the transfer of hydrogen ions from the water equallizing the imbalance of ions about your person?
Dry friction increases static charge.
Static charge leaks away in humid air.
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  #637  
Old 23.04.2008, 07:59
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Re: Ask a Scientist

Tell me about it...
The microbalances at the lab are very susceptible to static, so if it's very dry (as it has been for most of the winter), then all the lovely samples you make are in fact useless as the weight's not correct.
[/weeks of remeasuring]
It's not too bad when it's damp outside, but then sometimes the air pressure can play tricks on them as well, especially when workmen have the front door of the building open.
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  #638  
Old 24.04.2008, 20:23
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Re: Ask a Scientist

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That's actually really a very common misconception. How antibiotics actually work is that they shut down the synthesis of certain key compounds that bacteria need to survive. So basically, what the antibiotic does is go into the 'active site' of a protein, kind of like a lock and key fit (protein being the lock, antibiotic being the key, well a key that gets stuck). The molecules that need to go in there for the bacteria to survive can't because there's already something in there (something that doesn't want to leave). However, if the bacteria mutates and the protein (lock) is no longer exactly the same (but still viable) the antibiotic 'the key' no longer fits snugly into the lock and the bacteria can again make what it needed to to survive.

Which is why it is a good thing that our bodies don't metabolize the antibiotics, or else they'd never make it to the bacteria to do their job, but a bad thing because they are now making it out into the environment.

EDIT: That's actually how a lot of drugs work, they stop something from being made by a protein. Understanding the fundamental intermolecular interactions that make the "key" fit the "lock" is a huge portion of the research that my lab does.
What about antibacterial soaps and detergents? Do they also carry the downside of helping the development of resistant bacteria strains?
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  #639  
Old 24.04.2008, 20:57
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Re: Ask a Scientist

Can someone make me some LSD ?

Last edited by thundersinner; 24.04.2008 at 23:33.
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  #640  
Old 24.04.2008, 23:30
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Re: Ask a Scientist

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What about antibacterial soaps and detergents? Do they also carry the downside of helping the development of resistant bacteria strains?
Unless chemgodess tells us different, they don't. Soaps and detergents mess up the cell walls of the bacteria in a generic way, so there is no spzcific lock and key. Therefore there is no way for bacteria to find a way to avoid their effects.
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