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Everything posted by Glider

  1. All neurons are myelinated with the single exception of C fibres. These are very small diameter 'primary afferent' polymodal fibres associated with detection of temperature change, noxious cold and noxious heat. Along with A-Delta fibres, C fibres are often called 'pain fibres' (C fibres are associated specifically with 'slow pain'; the burning, aching and diffuse pain that comes after some trauma. Being small diameter and non-myelinated, they have very slow conduction rates, about 0.5 to 2m per second, compared to say, large, myelinated motor neurons which conduct at around 300 - 400 metres per second. We could not function if all central nervous system neurons conducted at that rate. It would give us a reaction time in excess of 2 seconds as opposed to the average human reaction time of 500ms (that would select us out of the competition very quickly). All CNS (central nervous system, i.e. brain and spinal cord) fibres are myelinated. The only difference between myelination in the CNS and the PNS (peripheral nervous system) is the type of cell responsible for myelination. In the PNS these are Schwann cells. Each of these wraps around and insulates a short length (about 1mm) of a single axon. In the CNS, oligodendrocytes provide myelination. These cells project to and wrap a portion of several axons so they also provide a kind of '3D scaffolding' as well as myelination. Multiple Sclerosis (MS) is a progressive de-myelinating disease and provides a good example of what happens when neurons (other than C fibres) begin to lose myelination. Information on myelination can be found in any introductory books on Human Biology, Psychobiology, Cognitive Neurosciences or Neurology.
  2. I saw this and wonder why you were impressed. Adnan Oktar (aka Harun Yahya) is not a clever man.
  3. It is a lot more complicated than that. At the most basic level, morality involves such things as the hard-wired characteristics evolved by social animals in order to function adaptively as social animals. One of these characteristics is empathy (which is also a part of the learning mechanism in humans); we can put ourselves into the position of another and imagine what it would be like in their situation. We have the neurological mechanism for this in the form of mirror neurnons. However, empathy in based upon personal experience (as is the function of mirror neurons). This most basic component probably underpins the golden rule. On a higher (though not necessarily better) level, morality also involves social learning and socially acquired mores which are generated by the culture in which one is raised. Thus, morality differs between cultures and changes over time. These are very basic elements. After that, it gets complicated. There are individual factors such as cost/benefit estimations; estimations of personal responsibility/accountability; personality characteristics and so-on.
  4. it would be hard to do since unlike most animals, plants and plant matter also have the capacity to become indefinitely dormant. Seeds for example are not alive in the strict sense. They are 'viable' and can remain so for a very long time. Willow is a good example. Fence posts mafe from willow, if they are 'rustic' (i.e. do not have the bark and cambium layer stripped from them) can throw out new shoots after being hammered into the ground (i.e. replanted) months after they have been cut. This actually recreates a from of propogation that the willow has evolved. Other plants (e.g. the rose of Jericho) can enter a dormant state indefinitely but return to the flush of health under the right conditions. In humans and other animals, death is a process, but it is comparatively fast (minutes) and can be measured (arguments about brain-death and brain-stem death aside, which are more moral than physiological points for debate). In any event, animal death can be described as the point at which metabolism ceases. In plants, this description does not work as lack of metabolism does not mean death. In plants, death can only be described as the point at which the material has become too degraded to recover even under optimum conditions. This varies hugely from plant to plant (grain from tombs in the Valley of the Kings has been germinated). Willow cambium present in fence posts can remain viable for as long as it doesn't dry out comletely, or rot. Exposure to the right conditions will trigger metabolic processes (i.e. growth). So, in the fence post example, the tree was cut down and further cut into sections, but the cells of the willow cambium were not dead. Nor were they alive. They were dormant, but viable and that is a hard state to measure. The only thing is to create ideal conditions and see what happens.
  5. It's a Surinam toad (Pipa pipa).
  6. The perception of the word 'condition' is primed by the pronunciation of the word 'stable', which has a West Midlands/Birmingham inflection so that the whole phrase 'Stable condition' sounds like it was spoken by someone from around Birmingham. Not as strong as say, Walsall or Dudley, but more like wolverhampton or Nuneaton. Most British accents emphasise the second syllable in that word. Does it matter? Yes. I've been there and it's quite discernable, but I was only there for a month, so I couldn't tell who was from where. The person I was with could though. She could identify people's origin by ear; 'aha! he's from Brisbane!' which, by Australian standards is only up the road from Sydney, in Queensland.
  7. I just listened to it. It is very good (sounds a bit like Johnny Depp/Jack Sparrow), but not quite convincing (to a British ear) because, although there is no Australian (I don't know where the others are getting that), there is a subtle but unnatural mix of dialectic influence and inflection. By unnatural, I mean a mix that is internally inconsistent (i.e. contradicts itself) and wouldn't naturally occur. I'll give you a breakdown from the perspective of somebody who was raised from birth with three different languages (and so has a very sensitive ear, never having lost the ability to percieve phonemes, that is extinguished in the first year in people who are are raised only with their native language and local dialect). NB. This is not criticism, it is critique. I hope you find it useful (as it is intended). Here's what I mean: "Boy hurt in park Lightning strike" This is very good. It sounds North London (Well spoken Muswell Hill/Highgate areas) "A sixteen year old boy suffered a cardiac arrest and five others were hurt in a lightning strike in a Birmingham park" This sounds a little slurred. Like the same person, but after three or four tequilas (Johnny Depp/Jack Sparrow does this too). The word 'others' came out with a Liverpool influence. In the South-east (inc London) it's more: 'Uthers'. "The teenager is in critical but stable condition following the incident in Spaldheath Park at sixteen fifty BST, said West Midlands Ambulance Service" Like phrase 2 except the word 'Stable' which contains a strong West Midlands/Birmingham influence (Staayble). There was a little Kiwi in the the words 'said' and 'service' too. In SE England it's 'Sed' and 'Servis' in NZ it's more 'Sid' and 'Servus'. "Five other teenagers were also taken to hospital. It is believed three are still in hospital, under observation" The dropping of the aitches in 'Hospital' is inconsistant with the well spoken tone and stick out a bit for that reason. "A spokeswoman for the ambulance service said it received several 999 calls followinng the incident. She said five ambulances were sent to the scene as well as a rapid responce motorcyle and an incident support officer and a senior paramedic manager" Again, the dropping of the 't' (and use of glottal stop) in 'motorcycle', whilst common in so-called 'Estuary English', is inconsistant with the overall well spoken tone and stands out for that reason. "Crews arrives at the park to find a teenage boy recieving CPR from a member of the public, she said. The sixteen year old boy suffered serious burns after being struck by lightninng and was in cardiac arrest." Here, the most notable inconsitency is the Liverpool influence in the words 'Public' 'sixteen' and 'struck'. "Crews continued emergency medical treatment on the boy and transferred him by land ambulance to Heartlands hospital. A second teenage boy suffered convulsions consistent with an electric shock and was treated at the scene before he was also taken to Heartlands hospital." The word 'taken' has a fairly srong West Midlands/Birmingham influence (i.e. 'taayken'). The second use of 'Heartlands' also has this 'Brummmy' sound, but what makes it stick out is that it is inconsistant with the first. "The four other teenagers suffered minor injuries and were assessed at the scene before three were taken to City hospital, and one to Heartlands." In this section, the word 'Heartlands' is very good, but the glottal stop in the word 'City' is inconsistant with the overall well spoken tone. Overall, it's really very good. I think the thing to aim for is internal consistency, where any one word used sounds identical in subsequent uses. It is this inconsistency that people will detect. As long as it's consistant, any overall innacuracy is likeley to be attributed to accent/dialectic influence (Maybe he lived abroad for a while?). If it's inconsistant, then it's obviously fake. A good example is Renée Zellweger, who can do an almost flawless 'Home Counties' British accent. It's generic and can't really be placed, but its so internally consistent that a listener never gets the urge to try to place it anyway, which is a major part of its success.
  8. No, it isn't. Even if it was, that would not constitute a pandemic, merely an acute localised outbreak.
  9. Be my guest. It's dissapointing how useful it is in teaching these days
  10. Well, there are mid-point arguments, for example, the idea of reciprocal determinism which is one of the central priciples in Health Psychology. This is the principle that we are both producers and products of our environment. Environment does, to a large degree, determine behaviour. However, we maintain 'executive control' (i.e. we can override primary behavioural urges).
  11. It's what I keep telling my students. "The fact of publication in a peer reviewed journal is a necessary, but not sufficient condition for citing the work of others. You should actually read it and not persist in trying to bypass your brain entirely".
  12. I don't think so. The statement "If the question is between either free will or determinism then determinism wins. is conditional. The statement 'IF it is between A and B then B wins' is not the same as saying 'the choice IS between A and B'.
  13. It is true that in general, some physicians are beginning to question the wisdom of prescribing medication that ultimately serves only to suppress the body's own defence mechanisms. People have got so used to the 'there's a pill for everything so I never need to suffer approach that millions are spent each year on pallitative medicines for trivial illness (cough, colds etc.) that do not cure the illness but merely suppress the symptoms. However, coughing, sneezing and dribbling are all reparative and protective mechanisms and are the body's way of clearing out the detritus of infection. With relatively minor illnesses such as upper respiritory tract infections (URTIs), coughing, for example, is physiologically useful. Medics are now beginning to question whether the patient's desire not to cough does in fact outweight the usefullness of the cough as a reparative/protective mechanism (for clearing detritus, ventilating properly and thus reducing the probability of opportunistic secondary infections, e.g. pneumonia). Some medics are now beginning to advise that people with URTIs simply drink lots of fluids, keep warm, rest up and deal with it. Recently, some cough/cold remedy was withdrawn for children under 6 years old in the UK. I can't remember the details, but the principle was that this palliative treatment was doing more harm than good by suppressing natural, physiological processes in children, putting them more at risk of secondary infections than if the illness was just left to run its course. The cynic in me suspects that palliative cough-suppressants for children are often used more for the benefit of parents anyway.
  14. In stringed instruments, the energy of the vibrating string is transmitted to the soundboard via the saddle and bridge. All stringed instruments, fretted or otherwise have a saddle and bridge arrangement of some kind. The string is under tension and is raised from the soundboard by the saddle, which is usually made of some hard material such as bone, ivory or hard plastic. The saddle is inserted into the bridge in a tight, interference fit and the bridge is connected directly to the soundboard. When the string is struck, its vibrations are transmitted through the saddle and bridge to the soundboard, which is usually made of some selected tone wood (i.e. a wood that is known to vibrate in a certain way, e.g. in Martin guitars it's Sitka spruce or mahogony, depending on the model). The soundboard vibrates and this moves the entire volume of air in the body of the guitar. The pressure waves (i.e. sound) exit the guitar through the sound hole (the big hole in the front that you drop the pick into every now and again). So, in short, the saddle and bridge transmit the vibrations of a string to the large area of the soundboard which also vibrates and causes the entire volume of air on the body to vibrate (the vibrating soundboard is the source of amplification) and pushes air waves (sound) out of the sound hole. The saddle and bridge are the key to the whole thing.
  15. That looks good. I just had an idea. You might want to look at the structure of baleen (also keratin). Baleen plates are very similar in overalll structure to feathers (but huge, being in whale mouths). A smaller version might be exactly what you're looking for. Here's a link to the wiki page on baleen.
  16. Feathers, including penguin feathers and peacock tails, are only modified scales, and a hair that's hollow but flat is weird and implausible? One of the wonderful things about nature is that it's really hard to outweird it. Any bizarre thing you can think of has probably already been done by nature. Hair is essentially keratin. You want hollow hair? Look at deer, karibiou, polar bear. You want hard pointy hair? Look at rhinoceros, you want flat and hard? Look at pangolin scales. You want hard, hollow and pointy? Look at everything from echidna, hedgehog and porcupine quills to bison and bufflao horn. It's all the same stuff. Hollow and flat is a relatively minor adjustment to any of these forms that would probably happen eventually anyway if it provided an advantage to the animal.
  17. Yes. Hedgehog spines and Porcupine quills are essentially hollow hairs stiffened with keratin. Even rhino horn is made out of hair, so it can appear in many forms.
  18. Yes, short, stiff and hollow (for insulation). There is a very small deer deer that has hair exactly like that. In its environment, the temps vary between 30 degrees C during the day, to below zero C at night. Its hair is quite short, but each hair is hollow. To lose heat during the day, the hair stands on end allowing air curculation over the skin, but at night the hair lays flat and the hollow tubes of the hairs form a trapped layer of air like a blanket.
  19. Yes, but they were head blows that cracked his opponents skull and made 'blood rush out of his nose'. Jotaro, in a fit of anger, also killed a man with a bokken and that too was a head blow.
  20. Physical characteristics like the propensity to produce higher or lower levels of dopamine or 5-HT or receptors for such transmitters and so-on?
  21. That's very true. For the best effect on the audience, these things should come naturally; you should appear relaxed. It is hard initially, but it will come together if Mokele's advice is taken; 'Practice'! One thing I could add is; remember to pause. One of the toughest things to handle when new to lecturing or presenting is silence. The slightest pause is torture. The result is that you try to fill it and begin to talk rapidly. Then you find you're running out of breath and then you begin to breathe in more often and rapidly to compensate. You'll find you breathe in too often and your lungs are full and you're speaking a few words and trying to breathe in again and, it, be, gins, to, sound, like, you're, sob, bing. Stop! Pauses, particularly well placed ones, can be very helpful in adding emphasis and it gives you the chance to breathe out. Take that chance. Breathe out fully, and take a normal breath before speaking again. It'll help with delivery and it will also calm you down if you're nervous.
  22. Death is a process. It's not like a light being switched off. Things shut down at different rates, it just usually begins with the heart. 'Clinical death' is just a term, usually referring to suspension of respiratory and (or more usually) cardiac activity that, without intervention, will result in everything else shutting down within a few minutes. When a person dies, not all their organs are ready to die at the same time, but when cardiac activity ceases, the other organs will die of ischemia within minutes (different times for different organs). The brain is the important thing to protect as it only has three to four minitues before it begins to suffer irreversible damage as it dies. People who go into cardiac arrest will begin to suffer cerebral ischemia very quickly. They will pass out within seconds (if they were conscious to begin with), but even then, it takes a little while for the brain to die completely. If the circulation is not restored, neurons begin to fire randomly as they begin to die. This has been proposed as the source of the 'bright tunnel of light and seeing dead relatives' near death experiences people sometimes report. if the neural firing during ischemia is random, why do so many people report such similar experiences? Because all humans brains and the relative oxygen demands of respective neurons and nuclei are also remarkably similar. The process of ischemic death in all human brains is the same and is therefore likely to have the same effects. By intervening with CPR, adrenaline (epinephrine) etc. at the point of 'clinical death', the process can be interrupted, sometimes.
  23. Exactly. Predictions allow the testing of theory and theory is the strongest construct in science. Theory is explanation.
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