Jump to content

John Cuthber

Resident Experts
  • Content Count

  • Joined

  • Last visited

  • Days Won


Everything posted by John Cuthber

  1. Lucaspa, The images raise awareness of both greenpeace and the whaling. I wonder how you expect greenpeace to do anything without raising money to cover the costs of doing it.
  2. "Then lets move to Asbestos, which claimed was the cause for ALL respiratory problems for years" Who made any such claim?
  3. Well, OK I agree that if your father died in a crash but it's listed as smoking related then the stats are skewed. I'm pretty sure that the statistical link between smoking and, for example, lung cancer is so well researched it's practically certain. I work measuring things- generally concentrations of pollutants in air. I know that some time ago when I was involved in measuring exposure to a chemical that people were working with and some other people were asking the same workforce to fill in a questionnaire about health, lifestyle etc. we got a rather disappointing result. The measurements of chemical exposure we took were very badly correlated with the health issues that the people had. The only statistically significant observation was that respiratory ill health correlated with smoking. That wasn't what we set out to find- it's just such a big effect it tends to swamp other things. If you look at demographics you find a whole lot of interrelated effects. If you look at incidence of lung cancer in a particular group like 70 year old men, then the stats are pretty clear. You find the highest incidence among heavy smokers, next highest among those who worked or lived with smokers or who smoked a bit and very low incidence among those who were not exposed. Prior to WWI lung cancer was a rare disease- even among the elderly. Nobody smoked. Now it's relatively common and a lot of people smoke. There was a ban on smoking in public places in Scotland quite recently- allready the statistics are showing the benfit of the reduction in smoking that resulted from this. Another point is that, like all drugs, nicotine has side effects and these are not generally benficial. The other trash in smoke doesn't help, but don't forget that nicotine is about as toxic as cyanide.
  4. I'd not bother with magnetometry. I'd dissolve the tablets in dilute acid, oxidise with H2O2 to get it all into Fe(III) then measure it colourimetrically. If I wanted to be classical about it I'd not oxidise the extract, I'd send it through a Jones reductor and then titrate the eluant with KMnO4 I have a feeling that you would need to do some sort of purification of the coffee extract before you could do a UV determination on the caffeine. I'd bet on chromatography. Not sure about the sunscreen- some sort of absorbtivity measurement.
  5. Don't forget that all the concentrations there have to be expressed as normality ie gram equivalents per litre (which is that same as molarity for nitric acid, but not for sulphuric). Only bother to read the next bit if you would otherwise point out the error. Strictly the units only need to be g eqiv / volume- it would still work in cubic feet but that's just complicating things.
  6. I think insane alien is mistaken. It would work. The alphas would plough into the other plate and charge it + while the electrons left behind would charge the alpha emmiting plate -. The same goes for the betas (the other way round). In fact, you only need one source.
  7. Also, while it's hot make sure it doesn't oxidise in air and give zinc ozide and SO2. If you are trying to get something to glow in the dark then I think the big problem is that the real stuff is made in a rather complicated way to get the best performance.
  8. Interesting chain of logic. I asked precisely one question; it was this "Still, what other product can you think of which, when used in accordance with the manufacturers instructions, has a 50:50 chance of killing you?" It seems the answer is "There is a 100% chance that eating carrots will kill you. A survey made in 1900, showed that every one surveyed had at some time eaten a carrot or carrots. Almost all are now DEAD, and the couple still around really look bad, expected to die soon." BTW, are you sure about what you said. I'm quite happy to believe that they record incidence of tobacco use on death certificates. Are you sure that's the only way they decide that tobacco is the cause of death. I know the medical and legal professions can be idiots at times but that one seems to be a step too far. If it is then, since they don't do that in the rest of the world, the aparent risk from cigarettes in the USA would be practically 100% whereas it's different elsewhere. Surely that would becom a ludicrous anomaly. Practically everyone has tried smoking once. Does this mean that 100% of deaths in the USA are recorded as smoking related?
  9. Err, it's a fair point that the media exagerate things like it's going out of fashion, but since plutonium is roughly a million times more radioactive than uranium it's a reasonable candidate for this list. It has an LD 50 of about 50 µg/kg which is pretty low and it certainly got a mention early on in this thread. I think the problem with including it is that you would also need to include every radioisotope with an apropriate half life (too short and you will never get enough into someone to kill them; too long ant it won't do any harm).
  10. Careful addition of liquid oxygen to the fuel in a car could easily result in the car reaching the speed of sound. Unfortunately this will be in a multitude of directions simultaneously. Also, the driver wouldn't survive to claim any glory, in fact it might be difficult for his next of kin to find any bits of the driver big enough to claim for burial.
  11. IIRC the lifetime risk from smoking is about 50% ie half of smokers die from something related to it. Of course the lifetime risk from living is 100% - everyone dies. There's also the fact that even non-smokers die from things, like lung cancer, that are usually thought of as smoking related. Still, what other product can you think of which, when used in accordance with the manufacturers instructions, has a 50:50 chance of killing you? The fact that you don't smoke much now is pretty near irelevant. Nobody ever started off as an 80-a-day smoker. Like many people here, I think you should quit while you are still ahead of the game.
  12. SkepticLance, I think that's a fine method for determining whether or not something is self-aware, but it has a problem. All blind animals fail. Now, I'm not a great admirer of cats- as far as I'm concerened they just mess up my garden. I pointed out to some cat lover that cats are dumb- they don't even react to their reflection in a mirror. He pointed out that it could be because cats are smart- they know that the image doesn't smell like a cat so they know it's not real. Good luck applying the mirror test to an animal that generally lives in the dark and percieves its environment by echolocation. Also, re ""What Greenpeace should do is very clear and has been for years. Accosting whaling ships in the Southern Ocean does not work. If the leadership of Greenpeace is sincere, which I doubt, then they will work on the democratic process, since Japan is a democracy. They will set up an anti-whaling organisation within Japan, using the many conservation minded Japanese to run, and educate the Japanese people, in Japanese, about what is going on. " What, like this? http://www.greenpeace.or.jp/index_en_html Would you like to revisit your opinion of Greenpeace's sincerity? I think that it's quite sensible behaviour for them to continue the work that brought whaling under some sort of controll in the first place and to add on other strategies, like Japanese websites, too. I agree that the greenpeace boats out there with the whaling ships probably don't achieve a lot directly, but they provide vivid images that do a lot to raise awareness and raise funds.
  13. This table gives density vs mole fraction for sulphuric and nitric acids. http://www.kayelaby.npl.co.uk/chemistry/3_6/3_6_3.html
  14. Oh, BTW, I think the same problems (eddy currents and demagnetisation) will happen with magnetic bearings. They still work so the idea is perfectly plausible, I'm just not sure how many applications you will find for it. The "gogging" effect ie the variation in torque will be horrible if you only use 4 teeth but I can't see a problem with using lots (OK that's like a conventional gear) but it's still non contact, so no friction and no wear. It would be interesting to see what the people who do "nano machines" think of this- they have real problems with friction.
  15. I don't see Blair as the type to read much so I guess it was down to Rushdie's support from the literary world (rightly or wrongly). (and I think most of the queen's grandchildren are a bit old for Harry potter but that assumes they havew normal reading abillity.)
  16. Why are ethics and philosophy not open to scientific explanation? In the limit they both happen in human brains; they are the results of a very complicated set of chemical reactions. As far as I know religion doesn't really answer anything anyway- saying "because God said so" isn't an answer unless you explain God.
  17. You could do it with very clean glass. Paint the image on with silicone oil then spray a fine mist of water onto it. The mist will stay as fine drops where the oil is but will spread out to a thin layer where the glass is clean. That way you can really use water in the spray. Otherwise you are basicly looking at the world of invisible inks and developers. I'm sure google will help you with that.
  18. For this to work you need to keep track of which atoms are part of you and which are not. Breathing mixes them up. The door is a much simpler idea.
  19. Since nobody has specified the pressure in the helium ballon it is perfectly possible to have a helium balloon in a vacuum. You just need to be sure not to put much helium in it. BTW, I don't play baseball so I'm no expert but re. "at ground level look more like a baseball in the bottom of a condom". Wouldn't that be the wrong way up?
  20. Roughly how common is that?
  21. There are real losses due to eddy currents. On the other hand the idea that the magnets"wear out" isn't a real problem. The worst position for a magnet to be in from the point of view of demagnetising force is next to another magnet N to N and S to S. Any combination of gears will sometimes be less strongly demagnetising than this. Think about an ordinary bar magnet- it is 2 magnets stuck together head to head and tail to tail. If you cut it carefully down the middle you get 2 magnets. Since ordinary magnets are stable for years there is evidence that these gears should work well. On the other hand, normal gears are fairly efficient anyway so, except in a few odd situations, it's probably not worth bothering. The thread's title is misleading. These are not really gears so the fact that you can't have gears without friction doesn't apply. "Something that isn't a gear does something that gears can't" isn't very eye catching. "you need to remember conversation of energy." There's nothing inconsistent with the conservation of energy with using magnetic forces to move things. A magnet has, by virtue of the field) some stored energy. For you to say this energy "goes away" is actually a breach of the conservation principle unless you can say where it goes.
  22. Joy, Do you understand that there is a difference between "poodles are dogs" and "dogs are poodles"? Similarly, there is a difference between "liquids that acts like a solid under pressure are non newtonian" and "non newtonian liquids acts like a solid under pressure ". Since the second of these is what you said, but the first of them is true I still think you were wrong.
  23. "Are not arrogant and inconsiderate bicyclists equally as annoying as their counterparts in cars?" No, because they don't kill other people.
  24. I agree that you should "think before you drink"; it's darned hard to think properly afterwards. Anyway, I used to brew my own and the best advice I can give is keep everything clean. (Also don't prime bottles with too much sugar)
  25. Breathing might be an interesting problem too.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.