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Everything posted by Airmid

  1. Let's do a little statistical analysis - after all, this is a science forum. What do you think the chance is that two people, who are both interested in xenobiology and poetry, who both use the same kind of language, who both are prone to the same kind of spelling and grammatical errors, and who both are fond of using hyphens, show up within 10 days on a science forum? Airmid.
  2. Could you tell us a bit more about the situation? Do these sea urchins represent a problem? I guess so, because you describe them as a "plague". But simply having a lot of these animals around doesn't necessarily mean that there is a problem. So, can you give us some details about what the problem is about? I did a little searching myself, and found with the following information: The long-spined black sea urchin. Algal cover and sea urchin distribution at Madeira. These gave me a little background on the sea urchins, but they didn't tell me what the problem was. So I'd appreciate it if you can help us out. Airmid.
  3. Yep, it might well be that the answer is "marsh plants". I found this article on the web about Potamogeton pectinatus, a typical marsh plant. Here's a bit from the introduction: Because the plant goes through the process every year one could indeed say that it "respires anaerobically throughout it's lifetime". Airmid.
  4. Reptiles (and dinosaurs) are different from mammals in that they don't have a fixed body size. The longer they live, the bigger they become. So it might have been easier for dinosaurs to become giants than it would be for mammals, as long as they managed to live long enough. Reptiles can also grow very fast. They are cold-blooded and so they don't need to spend energy from food to keep their bodies warm. There's a discussion going on whether dinosaurs were cold-blooded animals, or whether they were more like warm-blooded birds. Perhaps they even used a kind of in-between strategy. Anyway, the dinosaurs had a very good background to become giants. It seems that growing large has an evolutionary advantage, but the environment and the general body plan of the animal must allow for it. For example, food and oxygen must be plentiful. Larger animals sometimes become more sluggish, so predators must be absent or the animal must have other means of protection. The leg bones must be strong enough to support the mass of the creature. It isn't just dinosaurs that managed to grow to gigantic size. Check out some of the other Megafauna. Islands, where predators are absent, have yielded some huge animals. Dinosaurs didn't influence the environment like the microbes did. After all, microbes have managed to "pollute" out atmosphere with loads of oxygen which made animal life possible. But they would have had some influence, like mammals have today. I think they had a bigger influence on other species than on the environment. As predators, they would have "helped" their prey to evolve: by killing off the weaker individuals the whole of the prey species would become faster, or stronger, or better at hiding. But not all dinosaurs were predators. There were very many species of dinosaurs that ate all kinds of foods. And that would probably have been their greatest impact: there simply wasn't room (in terms of ecological niches) for other kinds of animals to find a way to make a living. After the dinosaurs were gone, suddenly there were plenty of opportunities for mammals to find food and prosper, and mammals took over the role that dinosaurs had before. So, in this way, the mammals are the new dinosaurs, and I think another "new dinosaur" will only have a chance to evolve when the mammals are gone. Airmid.
  5. I think you need to ask yourself the question first: what does "n=4" exactly mean? And "n=2"?
  6. To my knowledge, parasitic plants don't have a metabolism substantially different from green plants. Of course, they don't photosynthesize (or photosynthesize at a reduced rate) and instead they leech metabolites from a host plant. But they process these metabolites in the same way as a "normal" plant. As to the original question, I can think of 3 answers that are probably all wrong. The first answer would be "yeasts" or "bacteria". But yeasts or bacteria aren't plants so that would rule out this answer. The second answer would be "none". I can't think of any plant that specializes in anaerobic respiration. The third answer would be "all". All plants are capable of carrying out anaerobic respiration, and they do this when oxygen is locally or temporarily depleted. It's the same process that takes place in our muscles when we can't keep up oxygen supply: sugars are fermented to lactic acid, which still yields a bit of energy when oxygen is lacking. But that doesn't really fit the question either. So I am as intrigued as you are by the question! By the way, what is the level of your education? Should we be looking for a real complicated answer or a more simple one? Airmid.
  7. Like others in this thread said, there's not one definition for Life. I think the most generally applicable definition that is in use at the moment, is NASA's: a ‘chemical system capable of Darwinian evolution’. This is the definition that Astrobiologists commonly use when considering life on other planets. Virusses fit this definition. Crystals, however, do not. Crystals are able to self-replicate, and even introduce tiny errors in "child-crystals", but the errors are not inherited, and therefore crystals are not capable of Darwinian evolution. To anyone who is interested in defining life and astrobiology, this fairly recent review article is a darn good read! Airmid.
  8. Interesting thought.... can you explain a bit more on how chaos theory might account for teleological evolution or point me to a source? (Perhaps I should have moved this to the Evolution forum.) I find your points on intelligence and technology interesting too. You're focussing on tool use, and I would call this kind of intelligence Problem Solving. And indeed, big brains are not a prerequisite to solve problems, as countless tests with different kinds of animals have shown. I agree that the ability to solve problems is the basis of Technology. However, I think the Problem Solving is not the basis of Science as we know it. What's needed for science is some kind of curiosity, or the need to make sense of and predict the world around us. One could think of children asking "Why...?" all the time, or of people asking themselves "What would happen if I...?". I think this is what created first religion, and later on science. Which leads me to the following questions: Does Technology require Science? Does Science require a big brain? I'd say "Yes" to the first question. Science gives us the tools to solve problems, and thus is necessary for Technology. I'm not too sure about the second question. I've been thinking that learning by watching might point to the ability to do science, because this answers the question "What would happen if I...?" without actually trying it out. If this is the case, then a big brain is not required, since all kinds of animals, including fish are probably capable of learning by watching, though it would be interesting to know if ants are capable of this. Admins, sorry for taking this thread more or less off-topic, feel free to move this! Airmid.
  9. First a word of warning: fooling around with random bacteria can be dangerous. There's always a chance that you'll find a pathogenic type of bacteria, even in samples that seem harmless, like soil samples. Through isolation and culturing, you are allowing the bacteria to multiply freely and fast, and so you should take precautions to make sure they don't get released in the enivonment. So don't do this at home; and ask your biology teacher how to handle media, samples and bacteria. You don't need a sterilized lab. The agar plates that you use need to be sterile, though, and also the tools that you use. You also need proper techniques to make sure that nothing unwanted gets into your petri dishes, and that nothing gets out. Ask your teacher about this! Also, when you're done with with the experiments, make sure the used petri dishes get sterilized again, to kill off all the bacteria that you grew. The trick to get a pure culture, is to dilute your sample a lot, so that only a few bacteria are present in each milliliter. A milliliter of the diluted sample is then spread out on agar plates. If everything goes right, after incubation, a few bacterial colonies will have grown on each plate; each colony is the progeny of a single bacterium. If you transfer a little of a single colony to a new agar plate, you will obtain a pure culture. Whatever sample you use, there is always a chance that you obtain a pathogenic kind of bacteria. Normally, biologists use specially prepared media for this kind of experiment. Those media already have the acidity they're aiming for, and also contain a buffer. Growing bacteria can influence the acidity of their environment substantially, through the nutrients that they take up and the waste products that they excrete. But if a buffer is added to the medium, the acidity still stays more or less the same. The pre-prepared agar plates that you want to use probably already are buffered for a certain pH, so it's not going to be easy to change their acidity. I think the best thing you can do is to ask your teacher if it is possible to order different media, that already have the (buffered) pH that you are aiming for. Airmid.
  10. Did you guys ever read the West of Eden series by Harry Harrison? I enjoyed it a lot, and it has lots of great biology, sociology and linguistics in it. It's not hardcore science fiction, but I guess that's the way I like it. *smiles* Airmid.
  11. My guess is that you ran into a flock of luminescent dinoflagellates or bacteria. I also found this picture. Did what you saw look anything like that? Airmid.
  12. A few thoughts: As a biologist, I realize that "being social" is a great survival strategy for a species. A few examples: social wolves can tackle larger prey; social ants can support a very large standing population; and social hyenas can fend off larger predators. Social behaviour leads to a differentiation in roles: some individuals gather food, while others stay behind to guard the nest, and so on. Social behaviour also comes at a cost: the food gatherers have to feed the ones who are left behind on other duties. If they fail to do so the system collapses and as a result, the species suffers. As a species, we owe our success to being social, and one giant thought leap brings me to the conclusion that being social(ist) is the way to go for the continued success of our species. ParanoiA also mentions that all scientists tend to have a more left-wing view on economy. I think that is correct, and I also think it's quite natural. After all, it takes a certain type of person to engage into a scientific career. Research jobs in general don't pay very much, so someone who is primarily interested in making money is not going to follow that career path. So I think that the sciences mainly attract people who already have a more left-wing view on economics for whatever reason. Airmid.
  13. Not that I know of. We're not a very religious country, and I guess that made a difference. Contraceptives have been widely available since the early 60's. Even our catholic bisshops have ok-ed the use of contraceptives for married couples since the 60's. Feminism has had a big influence too, of course. Airmid.
  14. The other subject in this thread is about overpopulation. Since I'm living in a country the size of Massachusetts, but with a population of 16 million instead of 6.5 million, I thought I'd say a few things about our situation. First, about land use. Yes, we have very strict rules about land use. As you can imagine my country is pretty much urbanized. We have hardly any "wild" areas left, so what we have left is strictly protected. We have quite a large agricultural area, which is more or less protected too: every inch of our land has a land use designation (i.e. urban, agricultural, commercial, "nature", etc.) and changing the designation of a piece of land is a major political decision. And yet our population is (slowly) growing, and people need to live somewhere. We've come up with a few solutions for this. - Build high. This has been attempted especially in the 60's and 70's, but wasn't a big success. Our soil is not really fit for building high, and people simply hated living in those high appartment buildings. So this has been aborted and the high appartment buildings are gradually being pulled down. - Create new land. A few hundred years ago my country was a lot smaller than it is now. Relatively large lakes have been made dry, and also part of an inland sea gulf in the most recent times. These areas are now for the most part agricultural areas. We have about half of the former inland sea (now a lake) left, and there are no plans to make this dry also, because it has received a "natural area" designation. - Increased efficiency of land use. This is our most successful solution. Compared to US houses our average houses are small, have 2-3 storeys, are built in rows instead of free-standing, and have very small backyards. All new housing areas (yes, there are quite a few of those, usually nibbling off bits of the agricultural areas) are strictly planned. In an attempt to keep the housing environment interesting, and break the monotony of row after row of houses, "green" zones are included also, and the latest trend is to make sure no road runs straight *wry smile*. - An attempt to spread the people more evenly over the country. Most people live in the west and the center of the country, a situation that has grown historically. Companies are currently being stimulated to move their offices to less densely populated areas, hoping that the people will follow. This strategy is a recent one, and has some success, and might help us out more in the near future. As I said above, the agricultural areas are more or less protected, and yet new housing areas are being build in former agricultural areas. It is mostly out of necessity that this happens. The growth of the population, and the trend to replace high appartment buildings with lower building blocks simply demand more land for housing. Building even smaller houses, or closer together, is not a realistic option at the moment. As a result, agriculture gradually has to do with a smaller land area, and yet has to keep up production. So, intensive farming is the norm here, and of course that causes a lot of new issues: environmental, animal wellfare, vulnerability to animal diseases, etc. Also a few words on transportation. I think I need to make a distinction between 2 kinds of transportation: home-work travel, and "household" travel. To start with the last: with "household" travel I mean short distance travel like doing shopping, bringing kids to school, visiting friends and family, going to the cinema, etc. This is not a problem. First, because we use the bicycle so much for short distances. This is historically grown, and as a result our infrastructure is adapted to bicycle use and has with all kinds of special facilities for bicycles. I think we're quite unique in the world in this. Second, all common facilities are usually close by, as a result of the rigourous planning that has been going on in the past decades. Home-work travel, however, is quite a different story. Somehow, even with our rigourous planning, we didn't manage to end up in a situation in which most people live close to their work and so we have a big rush hour problem. Here's some things we're trying to do to solve this: - Build more roads. This is the traditional approach to the problem, and it helped for a while, but it's not working anymore. - Gliding work hours. This method is widely used at the moment. People who have jobs that don't require their presence at strict hours usually can start work anywhere between 7 and 11 in the morning. This method works somewhat, although families with school-age kids still prefer the traditional work hours. - Work from home. This method is hardly used at the moment, and companies seem to object to it very much. - Getting people to use public transport. We have excellent public transport, at least compared to other countries, so this sounds like an excellent solution. And yet all kinds of incentives that are being tried to get people out of their cars and into the public transport don't seem to work. The subject is being studied intensively, and I hope we'll have some practical results soon. - Relocation of company offices to where the people live, and of people to where the companies are, and of both to less densely populated areas. This is going to be a slow process, since we don't want to force companies or people to relocate. Instead, a system of incentives is being used. Also some areas that traditionally had a commercial use are being transformed into housing areas and vice versa. - Even more careful future planning. You might think we'll end up as an horribly overregulated country this way, but this is the method that has yielded the best results so far. We already can't buy a random piece of land and start building a house or an office on it, and haven't been able to do so for decades. What's more: we don't mind. We really don't see this as a sacrifice. Airmid.
  15. This thread addresses indeed some of the problems my country is coping with, or is going to cope with very soon. The thread started with the stagnation of population growth. In my country, we're going to see the effect of that very soon. In the years after the second world war, there was an enormous enormous increase in births. In the years after, population growth levelled off and our population is still growing at a slow rate, even if you count in immigration. Our "baby-boomers" are going to reach old pension age soon, so we will indeed have a situation in which a relatively small work force is going to have to support a relatively large inactive group. We've seen this coming for years, of course, so we're more or less prepared, though there still is a lot of discussion about how much of a problem this is going to be. One side of the story is, that there will be many more people on social benefit than before. Also, the cost of public health care is going to go up. The irony here is that the advances in health care and medicine in the past decades is causing an extra problem: not only do people live longer, but they also tend to make more costs: they need to be cured more often than before, and the treatments are more costly. The money to pay for this has to come from somewhere. To cope with this, we've had some major changes in the past years. First, the retirement age has gone back up from 62 (or 60 in some cases) to 65. There's talk of making this 67, and at least the people are stimulated to voluntarily keep on working after they reach the age of 65. Next, major efforts have been made to make the state finances sound, so that implicitely a reserve has been build up to pay for the extra expenses. We'll still need some more money though, and there's still a political debate going about where this is going to come from. The left-wing politicians want to tax old pensioners, but only those who are going to receive a large additional benefits on top of their standard old age benefits. The right-wing politicians want to make cuts in other public expenses, especially in public health care. To pay for the extra public health care expenses, we've also had a major revision in our health care system in the past years. A few notes on the success of these measures: To have people work longer will of course generate (tax) money, but companies aren't too happy to have the elderly as employees, claiming that they are ill more often and also have a lower work efficiency. State finances are indeed sound at the moment, but I'm not sure if our efforts to do so account for that. The success of our economy depends for the most part on world economy and we have very little influence on that. The revision in our health care system was meant to increase efficiency and thus lower the costs. The results are mixed: there is some improvement in efficiency, but we're also all paying more than before. All in all we're not quite done yet, I think. However, there's also another side to the story. The elderly in our society are not an inert mass: they're consumers. There are going to be quite a large number of elderly people who will have lots to spend, because they have built up high additional pension benefits during the post-war decades, when our economy was doing very well. Also, the elderly are healthier and more active than before. So there will be whole new group of consumers to cater for, and this will generate a good number of jobs. The situation therefore is not only bad news. We'll have to see though, how it develops, and in what proportion the positive side is going to measure up to the negative side. Airmid.
  16. Thanks for that link! I watched a few sessions now, and found them very interesting indeed. I'll have to watch them all multiple times, I think, because there is so much information in them, and so many good points are being made. I'd say watching these conference sessions is a must for anyone who is regularly drawn into Science vs. Religion discussions. I enjoyed Neil deGrasse Tyson's talk the most so far; he's such a great speaker! Airmid.
  17. I'd like to discuss camp Guantanamo with you folks, especially with the Americans among you. First I'd like to ask you: Are you being informed about the camp by the news or by way of other information channels? What kind of information are you receiving that way? Airmid.
  18. Correct. (This is the mechanism used in green plants. There are other mechanisms, but I don't think you should let that worry you now.) I like this picture of the Calvin cycle. I think you're referring to photorespiration here. Wiki has a pretty clear description of the process: "As carbon dioxide concentrations rise, the rate at which sugars are made by the light-independent reactions increases until limited by other factors. RuBisCO, the enzyme that captures carbon dioxide in the light-independent reactions, has a binding affinity for both carbon dioxide and oxygen. When the concentration of carbon dioxide is high, RuBisCO will fix carbon dioxide. However, if the oxygen concentration is high, RuBisCO will bind oxygen instead of carbon dioxide. This process, called photorespiration, uses energy, but does not make sugar RuBisCO oxygenase activity is disadvantageous to plants for several reasons: 1. One product of oxygenase activity is phosphoglycolate (2 carbon) instead of 3-phosphoglycerate (3 carbon). Phosphoglycolate cannot be metabolized by the Calvin-Benson cycle and represents carbon lost from the cycle. A high oxygenase activity, therefore, drains the sugars that are required to recycle ribulose 5-bisphosphate and for the continuation of the Calvin-Benson cycle. 2. Phosphoglycolate is quickly metabolized to glycolate that is toxic to a plant at a high concentration; it inhibits photosynthesis. 3. Salvaging glycolate is an energetically expensive process that uses the glycolate pathway and only 75% of the carbon is returned to the Calvin-Benson cycle as 3-phosphoglycerate. A highly simplified summary is: 2 glycolate + ATP → 3-phophoglycerate + carbon dioxide + ADP +NH3 The salvaging pathway for the products of RuBisCO oxygenase activity is more commonly known as photorespiration since it is characterized by light dependent oxygen consumption and the release of carbon dioxide." Correct. If this wasn't done, the result would be a large amount of free energy, which the plant can't use and only would cause damage. By transferring the energy through the acceptor chain, smaller amount of energy are freed in each step, which can be used by the plant for instance to produce ATP. (I am aware that this is a simplified view.) Correct, see above. No. The chlorophylls and other light harvesting pigments mostly absorb light in the red and violet parts of the spectrum, and hardly use green light at all. The green light instead is reflected back, and that is why plants have a green color. Airmid.
  19. Let me get this straight..... you Americans have actually been subsidizing OIL COMPANIES? Why on earth would one want to do that? Airmid.
  20. Thanks folks, for putting me right. It took me a while to wipe out my misconceptions about gravity. It's amazing how important gravity is when you're trying to understand our solar system; not only for the formation of planetary bodies, but also for atmospheres and the "layered" composition of the planetary bodies. I think I'm on the right track now! Wow, that's an awesome example, especially because that sun is so very close in mass to our Sun! Do you have any idea how this sun compares in heat output to ours, or what the temperature of this Jupiter-like planet is? Originally this was based on two ideas: the idea that heavier planets would be attracted more intensely by the Sun (I know now that this is neglegible); and the availability of planet-building material. The center of the contracting dust disk would have been much denser than the perifery, but the emerging Sun would have vacuumed out the center much more than the perifery, so less material would remain to form planets close to the Sun. Again, I know now that this idea is largely wrong too. I would say now that the distribution of matter in the proto-solar system isn't really important; what matters more is the distribution of the velocities of the particles and molecules. Would you say I'm closer to the mark this time? *nods* There's pretty convincing evidence. Another good bit of evidence is the low iron content on the Moon. I have been reading that the water content of a planetary body gives us a pretty good idea where it has been formed. Would you agree with that? Also, is there evidence that Mars has experienced a similar violent past? Thanks again, folks! Airmid.
  21. When you interprete the number as a series of hexadecimals ("64" "65" "77" "65" "79") you will get a result when you look them up in an ASCII table. Does that help? Airmid.
  22. Officially..... only one: Mercury. But Mercury's size makes sense to me, because it is so much closer to the Sun, and the Sun would have "eaten up" most of the potentially planet-forming dust. (Again, I could be very wrong.) Beyond Jupiter, planets are getting smaller again, which makes sense to me too, because the planetary dust cloud would have been much thinner in the perifery. But Mars seems to be the odd one out. Of course, there's the asteroid belt beyond Mars, so the mass was available in that area of the solar system. By the way, I found the orbit formula and found that distance from the sun and orbital speed are directly related; and that the mass of the object plays no role in the formula. Is this because the planets are so light compared to the Sun? Airmid.
  23. Lately I've been reading about the formation of the solar system and so many questions presented themselves! Here's one: how come Mars is so small? Common sense tells me that the further from the Sun, the larger a planet can be. Please tell me if my intuition is right! Yet Mars is a lot smaller than Earth. One possible explanation I came across has to do with Jupiter. I read that the presence of Jupiter probably inhibited the formation of a planet in the asteroid belt: if a planet would have formed there, Jupiter's gravity would have pulled it out of its orbit. Would the same have been the case if Mars had grown somewhat larger? Another thing I don't understand is how Mars' orbit can be stable. It could be that my basic understanding of gravity is lacking. The way I see it, all planetary bodies in our solar system are falling towards the Sun. The orbital speed they have is crucial there: if a body moves too slow, it will eventually collide with the Sun, and if it is too fast, it will drift away from the Sun. Correct? If so, is there a formula that gives the relationship between mass, distance from the Sun, and orbital speed? If so, does Mars conform to this relationship, or is it actually Jupiter that keeps Mars in orbit? Sorry for asking so many, probably basic, questions! Airmid.
  24. Airmid

    Acid Rain

    That's right. You could do an experiment to that extent, with plants sprouted from seeds. But best do not use seeds that carry a lot of nutrients for the young plants, like peas and beans, but rather small seeds, like radish or cress. Airmid.
  25. Airmid

    Acid Rain

    Years ago I did an essay on acid rain too. It centered on the theory that not the acidity of the rain in itself was the problem, but rather the fact that it acidifies the soil and as a result frees up heavy metal ions that normally would be bound to clay and humus particles. But like I said, that was years ago, and I don't know if there have been any new insights in the meantime. As to the components of acid rain, Wiki has a lot of useful information. Nitric and sulfuric acids are the main components of acid rain, but there's others too. They all have the same effect though: they acidify the soil and surface water, and that is what causes the problems. Does the Wiki article give you ideas for a research question? Airmid.
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