21

Plant Sciences, Zoology & Evolution / Re: Could we have underestimated climate change?

« on: 07/05/2012 06:13:58 »

At least here in Belgium we don't have seasons anymore. In 2011 we had summer days that were colder than some winterdays. Spring was summer, summer was autumn, autumn was like spring again, and winter was like autumn again.

22

Plant Sciences, Zoology & Evolution / Re: New species of Hominid

« on: 07/05/2012 06:11:41 »

A 'species' is one of the most difficult things to define in Biology and based on conventions.

I believe, one of the conventions for mammals is that two species cannot produce fertile offspring, so to answer your question: If a group of humans evolve from the Homo sapiens sapiens that can make fertile offspring amongst each other, but no longer with Homo ss, then that would be a new species.

If you're talking about a new species of hominids evolving from primates, then indeed intelligence will matter probably, but I think they'd never be called hominid because we humans are too vain for that

23

Physiology & Medicine / Re: How does my heart generate enough pressure to circulate my blood?

« on: 30/04/2012 11:58:29 »

In the arteries and some arterioles, there is a flow back protection called valves. These make the blood flow in only one way. Also when going from heart -> arteries -> arterioles -> cappilaries, the combined diameter of the vascular system increases, so there's "more room" for the blood. After the blood has passed the cappilaries, it enters the venous system where the pressure is close to "0" and the blood gets 'pushed in the back' to the heart by new blood from the cappilaries.

24

Physiology & Medicine / Re: How long does it take a drop of blood to do a full circuit of the system?

« on: 30/04/2012 11:53:36 »

Depends what route it takes and how active the person is at the time. 

but total blood volume is ~5 liters, flow rate in aorta at rest is ~100cm³ per second: 5000/100 = 50 seconds

Indeed. The travel time is affected by route. All blood goes from heart -> lungs -> heart -> body -> heart -> lungs....
Now if the body portion of the route is your foot, it'll take longer to circulate compared to the body portion of the route being your coronary arteries.

25

Physiology & Medicine / Re: Does testicular cancer affect sperm cells and children of the sufferer?

« on: 30/04/2012 11:48:19 »

It's possible if you're unlucky.
If you have testicular cancer, and one (or more) of the spermato- stem cells has been altered, then all sperm cells coming from this/these sperm stem cell are altered as well. Now, usually, this will result in suboptimal motility/mobility of the affected sperm cells, which would probably make that one of your healthy sperm cells will reach the egg first and fertilize it. Then, in the case that you have the bad luck of fertilizing the egg with an altered sperm cell, then this will probably lead to spontaneous abortion due to mortal defects, which will allow you to try again next month, or two months after.

So you see, a lot has to happen before you would actually have children with congenital defects due to testicular radiotherapy.

26

Technology / Re: Is it better to use the engine to decelerate?

« on: 27/04/2012 06:32:27 »

[joke]How about full throttle in reverse gear for reducing stopping distance in emergency cases?  [/joke]

Actually, that would reduce your stopping distance if you could ever get the tires to spin backwards - it would work like a dragster in reverse.

I know it works in theory, but don't try to shift in reverse when doing anything above 20 Km/h, unless you have a somewhat decent amount of money you were otherwise going to throw away anyway

27

Technology / Re: Is it better to use the engine to decelerate?

« on: 26/04/2012 06:56:57 »

[joke]How about full throttle in reverse gear for reducing stopping distance in emergency cases?  [][/joke]

28

General Science / Re: What is science?

« on: 26/04/2012 06:42:30 »

Science = facts/data
Religion = belief/faith

Both have their merits and they don't need to be mutually exclusive

Not that religion was mentioned in the OP, but what merits does it have, exactly?

Well, for a lot of people, religion is a source of comfort, hope, solace, ....
Don't get me wrong, I'm pretty atheistic myself, but I'm not blind to see what religion can do for other people. Of course there are negative aspects to religion, but so are there to science, as Ophiolite already pointed out.

29

New Theories / Re: travel with light speed ?????

« on: 25/04/2012 13:22:36 »

so what, if we do not allow gravitational forces to feel the mass, that is we should change the mass at such a rate that
gravitational forces can not act on the mass,

So you want to change the mass of an object fast enough so that gravitation cannot act on the mass...
Let's assume an object with a starting mass of A. Gravitation will work on this mass.
Then you somehow instantaneously change the mass from A to B and let's say B is smaller than A. Then the Gravity field will change at the speed of light from mass A to B, but it will not stop working on the mass, unless you change the mass of the object to 0.

30

General Science / Re: What keeps a chicken from being asphixiated before it gets strong enough to brea

« on: 24/04/2012 14:35:25 »

The egg shell is porous and O₂-gas just diffuses everywhere it needs to be

31

Physics, Astronomy & Cosmology / Re: Red-shift of reflected light?

« on: 24/04/2012 14:04:36 »

Yes, if we're speaking photons they lose 'energy/momentum'. I've seen a lot of new formalism jumping between 'photons' and waves the last decades, without changing the original definitions? wonder why, if now a photon would have both a frequency and a wavelength?

But how is the loss of energy/momentum observed then in a perfectly reflective surface?

32

Physics, Astronomy & Cosmology / Re: Red-shift of reflected light?

« on: 24/04/2012 13:10:41 »

Couldn't it be that the light wave is only losing amplitude, and not frequency?

33

General Science / Re: What is science?

« on: 23/04/2012 05:48:56 »

Science = facts/data
Religion = belief/faith

Both have their merits and they don't need to be mutually exclusive

34

Physiology & Medicine / Re: What is the best way to reduce sensations of anxiety?

« on: 20/04/2012 06:52:42 »

Any ideas welcomed

Cheers

Ace

Cannabis.
And if you use a vaporizer to inhale it, instead of the well known joint, you'll greatly reduce (but not eliminate!) the negative side effects.

Disclaimer: Not suitable for pregnant women, and do not drive any vehicle, or operate heavy machinery will using this medicine!

Edit: Yes I am pro legalization! It's time that cannabis is regarded as a medicine with side effects instead of a drug. Alcohol is far more destructive and yet it's legal in many countries.

35

The Environment / Re: What will Earth's temperature be in 5000 years?

« on: 20/04/2012 06:40:50 »

However, without humanity, one might expect a new glacial cycle to begin sometime between now, and 5000 years into the future. 

So mankind did a good job burning all those fuels and possibly delaying the onset of the next glacial era, seeing as how a glacial era could, and probably would, be quite devastating for the best developed regions on earth. Now we're buying ourselves some extra time to solve this Cycle problem permanently

Obviously 5000 years is a long time in the future, and humanity will be tempted to intentionally directly modify our global climate.  Perhaps warming the poles, or attempting to decrease the annual seasonal temperature fluctuations.

On this, I can only agree. I predict that in the future there will be some curriculum on the university called "Climate Engineering" as mankind will be more and more able to manipulate it.

36

The Environment / Can oil be synthesised from CO2?

« on: 20/04/2012 06:26:30 »

http://wattsupwiththat.com/2011/03/29/the-greens-worst-nightmare-a-co2-to-oil-process/

If we would be able to make oil from CO₂ using only bacteria and sunlight, wouldn't that make all cars zero emission vehicles?
What are those greenies complaining about?

37

Physics, Astronomy & Cosmology / Re: Is it possible to make a lift/elevator to get into space?

« on: 20/04/2012 06:17:18 »

I think if everyone called it the centrifugal pseudoforce instead of the centrifugal force, there wouldn't be an issue.

That's like saying that if everybody in the world became a Muslim then we'd have world peace.

Maybe, if all oil reserves in the world were empty as well

There is no "flinging off". If gravity quit working, you would travel in a straight line tangential to the Earth's rotation.

Ignoring, of course, that without gravity, there would not be be an atmosphere, and the Earth would disintegrate. 

But, in your day without gravity.  Those people smart enough to tether themselves to Earth (for example tied to a tree), wouldn't find themselves flattened against the Earth with their rope at a tangent, but rather, they would find themselves hanging out at a perpendicular to Earth's rotation, at the end of their rope.  At the Equator, they would be hanging perpendicular to Earth.  At the 45^th parallel, they would be hanging at a 45 degree angle from the surface.  You could say that the tree that a person is tied to is exerting centripetal force on that person.  Yet, what would you call the force the person is exerting on the tree, tending to pull out the roots?  And, what direction are the roots pulled out?

And lean towards the equator? I'm not so sure about that. If I visualize in my mind's eye a rotating earth with atmosphere and without gravity, I think the person at the 45th parallel would also be hanging straight up, with maybe a slight deviation from perpendicularity towards the position of the sun, ignoring the moon's gravity field since it will fly away if earth's gravity is gone

38

Technology / Re: Is it better to use the engine to decelerate?

« on: 20/04/2012 05:53:44 »

Hi lunar11, engine breaking will indeed decrease your fuel consumption and increase the lifetime of your brakes.
In modern vehicles (or better, vehicles with modern ECUs: 'electronic control units'), you won't even use a single drop of fuel when doing this while you are in gear, because the car cuts off all fuel supply and uses the wheels coupling through clutch to keep the engine running above idle/stationary rpm. And just before the engine reaches the idle rpm, you'll need to downshift.
In older, "dumber," cars, the engine will use the same amount of fuel as if it were stationary when doing the engine breaking manoeuvre, because that's the amount of fuel that always goes to the engine when you're not touching the accelerator

39

Physiology & Medicine / Re: What is a memory? And how are memories stored?

« on: 17/04/2012 09:09:42 »

Hi Nizzle,

1.   Yes, it is neuronal connections, but I needed more than that because every memory is different and I needed to know what is the nature of the neuronal connections that makes a particular memory unique? Would the neurons be a unique chemical sequence for every memory?

I believe the uniqueness of each memory has not much to do with chemical sequences, rather with which neurons are involved. It's unclear what you mean with "chemical sequence"? Do you perhaps mean "anatomical sequence", or are you talking about neurotransmitter sequence? Like, first a neuron gets dopamine signals, then acetylcholine, then serotonin, ...

2.   True, the brain is different at any given moment. When one memorises something into long term memory, would the brain actually hard wire that memory (again, as a unique chemical sequence) into the brain?

When you sleep, short term memories get transcribed in long term memories. However, this is not an exact science and depends on a lot of factors. The hard wiring you refer to, could be seen as "a preparation of a neuronal connection, facilitating a future firing". I usually make this metaphor: If you're beating a tree with your hands all day long, as some shaolin monks do, your hands will get more callous and they will be better equipped for future tree-beating. That's what you do with your brain when storing memories. You're training specific neuron connections and reinforcing them so you can access them more easily in the future.

3.   Correct that the brain does not store and incident, but codes for the memory. If I told a lie and yet also remembered the truth about an incident, how would my brain differentiate between the two when I wanted to recall it? Ditto with reading it in a book, watching it in a movie, how does my brain know which memory of the incident is the lie, the literary version, the movie version and the reality? In what way are the neuronal connections different for each of those?

Did you know that when you're consciously telling a lie, your brain is using much more oxygen and sugar compared to when you're telling the truth, or at least what your brain has accepted as being the truth. Your brain can easily repeat a truthful memory, but when you know the truth, and telling a lie about it, it starts from the truthful memory and needs to work on it to make it a lie before sending the signals to your voice box and lips and tongue. So, a lie is a variation of the memory of the truth. What you see in movies or read in books, your brain will categorize in "truth", "lie", or "fiction". Now to your question "How does the brain know which is which?" Your brain is a clean slate at the very beginning of it's development (i'm talking pre-birth now) and will be molded and modeled from the very start by all sensory input it gets (tactile, visual, hearing, pain, ....) This leads to what is called "your reality". Every memory in your life can be brought back to a combination of sensory inputs, processed by your cognitive functions (example: eyes see inky symbols on paper, brain makes words of them because it has memories stored of each inky symbol), then tested against "your reality", and subsequently incorporated into "your reality". So "your reality" is also changing every second of your life. Every new incoming blend of sensory inputs (a future memory) that is in conflict with "your reality" will be perceived as a lie, even if it's not a lie. Example: a person that has only read fairy tales could say to you "All books start with Once upon a time.." and be truthful about it, because it does not conflict with "his/her reality", but it does conflict with your reality, because you have read other books too.

4.   My apologies. My question wasn’t clear enough: would the memory of my mother be encoded as the same chemical sequence in the brains of both my sister and me if we are both recalling a memory of our mother? I personally don’t think it would be, which brings up the question of epistemology in philosophy, but....it still begs the question: how do we encode memories of same person in different brains?

See also my response to question 3.

To recap how brains store memory.

1. Combination of all sensory inputs come in at the same time.
2. Processing by brain occurs. Instructions for processing are retrieved from previous memories.
3. Post-processed sensory inputs are tested against current state of conscious brain (your reality)
4. Post-processed and tested sensory inputs are incorporated in, and alter the current state of conscious brain (your new reality)
5. Back to 1.
IMPORTANT: Emotions also play a very important role in formation of reality, and your emotional state is very significant in all steps (1 through 4) in the above. Strong negative/positive emotions will lead to intense memories (the ones that will last a very long time), and the nature of the emotional state (happy, sad, stressed, tired, ...) will affect the context/content of the memory.

So, two persons sharing memories of the same person might remember that person in a different way. For example, your mother could have always been very nice to your sister, but very rude to you. You received different sensory inputs from the same person, which alter your reality in a different way.

Then, our brain also has a deeper layers, the unconscious layer, left-over primal instincts. Not much is known about this yet, and I'm not going to speculate

40

Technology / Re: how do you backup your ipod music?

« on: 16/04/2012 06:09:19 »

Uhm, how about the simple and legal way of using iTunes??
If you sync your iPod you can "uncheck" songs (or albums or folders or playlists) to be synced. This will make iTunes delete them from your iPod, but keep them on your PC