Remove the moderators.

I agree. :mischief:

Remove the moderators.

No, not quite. You have to remove something though.

Add more uranium.

The Coolant?

I agree. :mischief:
:lol: I can't believe I said that with you around.

Move the reaction rods closer together, add a bit more water and a a turbine with longer fan arms?

(rAdio70qical NoOb).

Throw petrol on it?

From what I understand about nuclear reactors, there are two things mediating the reaction: Fuel (usually Uranium), and Neutrons. So adding either, or removing the absorbtive medium (usually graphite) will increase the rate of the chain reaction.

But I honestly have no idea ;)

From what I understand about nuclear reactors, there are two things mediating the reaction: Fuel (usually Uranium), and Neutrons. So adding either, or removing the absorbtive medium (usually graphite) will increase the rate of the chain reaction.

But I honestly have no idea ;)

I suppose you could add more Fuel, but you don't really want to have to go into a working nuclear reactor every time you want to change it's power :nuke:


A nuclear reactor is a chain reaction. 1 Neutron hits a Uranium (usually) core, splitting it into two smaller cores, and releasing several (3/4) new neutrons. These neutrons can then hit new uranium cores.

The problem with this is that if all new neutrons would set about a new reaction, the number of reactions (= power) would increase exponentially. This would quite quickly result in too much power to handle, and then entire thing would explode/meltdown/become too hot.

Therefor, there are control rods to catch a certain percentage of the free neutrons, so that from the neutrons created in a single reaction, only 1 will start a new reaction. This is called "the k-factor is 1". That means the power is constant.

To increase it, you temporarily remove the control rods (you lift them up a bit), the k-factor becomes larger than 1, the power starts increasing, and once you reach the desired level, you lower the control rods again, the k-factor will be 1 again, and the power will be constant (but higher).

So Brennan got the answer several days ago! :confused:

Yeah, dutchfire just didn't do his homework.

DO YOUR HOMEWORK BEFORE ASKING, PEEPS!

Moderators are different from control rods. Moderators slow down the neutrons so that they can participate in further fission reactions, since slower neutrons can't be absorbed by U-238, and will therefore go on to react with U-235. Control rods absorb excess neutrons, as Dutchfire described.

The name "moderator" makes it sound like they should be doing what the control rods are doing, though.

Oh NEVER MIND then!

Moderators are different from control rods. Moderators slow down the neutrons so that they can participate in further fission reactions, since slower neutrons can't be absorbed by U-238, and will therefore go on to react with U-235. Control rods absorb excess neutrons, as Dutchfire described.

The name "moderator" makes it sound like they should be doing what the control rods are doing, though.

Yeah, dutchfire just didn't do his homework.

DO YOUR HOMEWORK BEFORE ASKING, PEEPS!

DO YOUR HOMEWORK BEFORE TELLING PEEPS TO DO THEIR HOMEWORK, PEEPS!

What Mise said is correct. :)

The moderator in a nuclear reactor is usually water, while the control rods are usually some sort of metal, alloy, compound or sometimes graphite.

PEEPS STILL SHOULD DO THEY'S HOMEWORK BEFORE ASKING QUESTIONS!

It's just that you already did! :goodjob:

PEEPS STILL SHOULD DO THEY'S HOMEWORK BEFORE ASKING QUESTIONS!

It's just that you already did! :goodjob:

And I'm glad I did, as this was the first question at my physics exam :D

...so who's up then? :confused:

It's Dutchfire again, but if he doesn't post in the next day, it's open.

peter grimes had it right, so he can ask the next question if he wants.

I must be getting out of date, control rods (esp boron) is exactly what I was thinking of. I'm sure they were called moderator rods in my day. :old:

I was just following Brennan's lead.

72 hours is stupid, should be 48, or 24. If you aint going to log before 72 hours then presumably you'd have the courtesy to notify someone, unless you got eaten by friggin' sharks with laser beams.

Just my two cents. Catharsis should change the rules, they don't make sense for such a high turnover thread/ forum.

Still nm, I'm sure this only happens once in a blue moon right?

The rules are what they are, so stop complaining about them. They're fine as is.

List 4 interesting properties of the number Phi.

Phi is the golden ratio, so it makes for very pretty rectangles and such. Greek architects used to use it for building stuff too I think. Not sure if that counts as "four" or "interesting"... :p

phi - 1 =1 / phi

the ratio of cn/cn-1 for the fibonocci sequence converges to phi.

The ratio of segments in a pentagram is phi

The sides of a golden rectangle have a ratio of phi

Perfection got it - I didn't even know about the pentagon one. I assume that means that the ratio of diagonals to sides, right?

The one that always baffles me is how Phi relates both to quantum physics as well as prime numbers :twitch:
Here's sort of an abstract (http://www.secamlocal.ex.ac.uk/people/staff/mrwatkin/zeta/goldenmean.htm) - I can't find the original anymore.

Perfection got it - I didn't even know about the pentagon one. I assume that means that the ratio of diagonals to sides, right?
http://en.wikipedia.org/wiki/Image:Pentagram-phi.svg

It's all the segments.

Perfy knows pentagons ;)


Speaking of pentagons...

Regular Triangles, Squares, and Hexagons can all form grids (as shown below), why can't pentagons? (I'm looking for an informal mathematical proof).

http://gwydir.demon.co.uk/jo/knots/tri1.gif
http://www.balloonhq.com/column/rouse/aug05/2SquareGrid_01.gif
http://gwydir.demon.co.uk/jo/tess/hexagon.gif

The sum of the angles around where they join must be 360, but pentagons have internal angles of 108 degrees, which doesn't fit into 360.

Yep. :goodjob:

The rules are what they are, so stop complaining about them. They're fine as is.

No they suck, Mr conformity patrol.

What effects does lactate production by exercising muscle have?

Apparently, if you stimulate men's nipples, they eventually lactate.

I think Brighteye meant lactic acid build-up from exercise. :lol:

As for the real scoop. this is what I'm recalling atm: Basically, lactate is the byproduct of anaerobic glucose metabolism in muscle, which should eventually occur with strenuous exercise. There used to be a theory that the lactate bound directly to muscle as an inhibitor, but that was disproven in favor of the lactate causing pH changes. I'm pretty sure there have been new clarifications in the past 1-2 years, but I can't recall what they were atm.

If I'm right, I nominate Mise to ask the next question. :lol:

You've talked about what's been disproven, but not what happens.

I think that if Sidhe is really as fed-up with this format as he appears to be, he should start a new Cumulative General Science and Technology Thread, where he can propose the rules he prefers. After all, it's not as if Thunderfall has proclaimed that there can only be ONE CGSTQ thread ;)

If his rules turn out to be the preferred format, then we will see a sort of 'evolution' of the format ;)

Was that too hard? It was news recently, with an article and editorial in The Journal of Physiology.

I didn't think so, but over the my years of education, I'd heard so many stories on it that I couldn't remember which was considered the most accurate. :) I thought it was a simple case of altering the pH leading to altering of protein structure.

Was that too hard? It was news recently, with an article and editorial in The Journal of Physiology.

I think we have more of a physics / maths memberbase than a medical memberbase.

I think that if Sidhe is really as fed-up with this format as he appears to be, he should start a new Cumulative General Science and Technology Thread, where he can propose the rules he prefers. After all, it's not as if Thunderfall has proclaimed that there can only be ONE CGSTQ thread ;)

If his rules turn out to be the preferred format, then we will see a sort of 'evolution' of the format ;)

Well I can understand how they might be sensible in a part of the forum that doesn't see much traffic, but because when a question is up this thread moves with some speed, I don't see why three days is sensible? 2 maybe, even 1. Just because something works in the CIII forum there's no reason it will work here, where there is a high turn over. If you ask me its up to Catharsis as its his thread, but something tells me he doesn't post any more. Maybe someone could change it at 1000 posts in a new thread? All I ask is that people bear it in mind, its obvious that 3 days is arbitrary and inappropriate. Last word on the subject.

I had thought that lactic acid was something that maybe any exercise people would have known about too.
Anyway, new question:
To reach statistical significance (a probability of occurring by chance of less than 0.05), what's the minimum number of experimental subjects required?

It's very simple maths, but maybe people won't realise how to translate the question.

IIRC, the "error" is just sqrt(n), where n is the number of trials. To get the percentage error, it's sqrt(n)/n, which is 1/sqrt(n). So, take the reciprocal of 0.05 and square it: that's 20^2 = 400.

I had thought that lactic acid was something that maybe any exercise people would have known about too.
Anyway, new question:
To reach statistical significance (a probability of occurring by chance of less than 0.05), what's the minimum number of experimental subjects required?

It's very simple maths, but maybe people won't realise how to translate the question.

30, I guess.

Well I can understand how they might be sensible in a part of the forum that doesn't see much traffic, but because when a question is up this thread moves with some speed, I don't see why three days is sensible? 2 maybe, even 1. Just because something works in the CIII forum there's no reason it will work here, where there is a high turn over. If you ask me its up to Catharsis as its his thread, but something tells me he doesn't post any more. Maybe someone could change it at 1000 posts in a new thread? All I ask is that people bear it in mind, its obvious that 3 days is arbitrary and inappropriate. Last word on the subject.

I do still post, but I haven't known the answer to any recent questions.

This format works well in the World History forum, which has a higher turnover than this forum, and I'm not going to change the rules mid-way through the thread. However, this thread is coming towards the end of its life, so when it reaches 1000 posts, if you get here fast enough, you can start the new one. 'Kay? :)

As for the question, linfeixb27's answer looks familiar.

You are happy with it? It's the only forum of any size I've seen with such a system? No accounting for taste, I presume it was implemented in the annals of history in threads with significantly low turnover, and people being what they are never thought to question the law. And I wont be fast enough and the new thread starter will no doubt implement the same rather unnecessary and outdated rules, so never mind. If everyone's happy with threads stalling for prolonged periods, then there's no more to say about it is there? Case closed.

No, and no. We need to show that a change occurs in whatever we're measuring with a probability that the change is due to chance of 0.05 or less.
Error doesn't really come into it.

Is this assuming a Normal distribution?


To reach statistical significance (a probability of occurring by chance of less than 0.05), what's the minimum number of experimental subjects required?

It's very simple maths, but maybe people won't realise how to translate the question.

20 ?

Closer.
Assume whatever distribution you like, as long as the null hypothesis doesn't make it a skewed distribution. That does distort the answer.

I assume that this question was too hard too.
In an unskewed distribution, the probability of the result going in one direction is half. The probability of each result going the same way is also half.
Therefore the minimum size of study can be solved with the equation (1/2)^n=0.05, where n is the minimum sample size.
N is between 7 and 8, so the minimum size is 8.

I'll try again:
What does nitric oxide do in the body? (Any one function will do)

relax and growth-inhibit smooth muscle
inhibit platelet aggregation
kill pathogens

Yep. Your turn.

It gives you erections too.

I assume that this question was too hard too.
In an unskewed distribution, the probability of the result going in one direction is half. The probability of each result going the same way is also half.
Therefore the minimum size of study can be solved with the equation (1/2)^n=0.05, where n is the minimum sample size.
N is between 7 and 8, so the minimum size is 8.

I'll try again:
What does nitric oxide do in the body? (Any one function will do)

Sorry, I do not understand most of your explaination, but I think (1/2)^4=0.0625, (1/2)^5=0.03125, so in equation (1/2)^n=0.05, n should be 4 or 5.

how old is the oldest known mammalian cell line in continuous propagation? and what is its species?

Wild guess: a human carcinoma cell line from about the 1950's? I'm pretty sure there were several around then, with the first name of their donors.

The cell lines are typically made from a fusion hybrid of a cancer cell with another cell, like a mouse cell.

Sorry, I do not understand most of your explaination, but I think (1/2)^4=0.0625, (1/2)^5=0.03125, so in equation (1/2)^n=0.05, n should be 4 or 5.

Sorry, I made two mistakes: first, we need a 2 tailed test, so p=0.05 actually means that the probability of one side needs to be under 0.025, and secondly, the answer is 6.

Thanks for picking up on that.

HEK cells?

Wild guess: a human carcinoma cell line from about the 1950's? I'm pretty sure there were several around then, with the first name of their donors.

The cell lines are typically made from a fusion hybrid of a cancer cell with another cell, like a mouse cell.

HEK cells?

nope and nope :p
and its not a man made cell line I am looking for :mischief:

The 1950ish original original human carcinoma lines were purely of an eternal cancer and weren't hybridomas, I believe.

are they from rabbit butts? (bun buns)

The 1950ish original original human carcinoma lines were purely of an eternal cancer and weren't hybridomas, I believe.

no and much older :mischief:

are they from rabbit butts? (bun buns)

no bun buns.

Edna Parker human cells, about 115 years old?

thats already pretty old not quite old enough though - but the key here is continuous propagation - which means they were never stopped, e.g. by freezing and restarting growth after thawing. This is something that cannot happen within a lab environment so think outside the lab :mischief:

Its actually a pretty interesting entity in cancer research - though more of a curiosity and scary if any such thing would occur in humans...

how old is the oldest known mammalian cell line in continuous propagation? and what is its species?

The Tazmanian wolf face cancer?
Henrietta Lacks?

(NO is also used as a retrograde signal in neurons)

HeLa as most lab cell lines is from the 1950s which is too young.
Devil Facial Tumor Disease is on the right track, though. It is a cancer cell line that propagates itself by allografting (transmitting) onto its next host during contact. This cell line emerged in 1996 - so its not really old :) and will likely eradicate its host species too soon to become as old as the one I am looking for :( :sad:
it is however only the second instance of this type of cell line - and I am looking for the first one...

A haemapoetic stem cell line from a blood transfusion? That would be pretty cool.

A haemapoetic stem cell line from a blood transfusion?
:nope:
That would be pretty cool.
and scary as hell if you think of it :eek: - but no its quite capable of propagating itself without human intervention :devil:

Ok I'm thinking vegetables now.....with big hacking vegetable tumors.

Agrobacterium tumerfaciens?

Some form of kitty or doggy cancer?

Ok I'm thinking vegetables now.....with big hacking vegetable tumors.

Agrobacterium tumerfaciens?

never seen a mammalian vegetable :p

Some form of kitty or doggy cancer?

now give me the age and you win :)
doggy cancer it is...

25 years?
50 years?
75 years?
100 years?
150 years?
200 years?
250 years?
300 years?
400 years?
500 years?
750 years?
1000 years?
1500 years?
2000 years?
3000 years?
4000 years?
5000 years?
8000 years?
10000 years?

130 years old?

130 years old?

It was discovered 130 years ago, but it is a tad older:


200 years?
250 years?
300 years?
400 years?
500 years?
750 years?
1000 years?
1500 years?
2000 years?


Perfection got the doggy cancer right - and with brute force found the age...

The answer is Canine Transmissible Venereal Tumor:


CTVT, also known as Sticker's sarcoma, is a histiocytic tumor that is usually transmitted among dogs through coitus but may also spread through licking, biting, and sniffing tumor-affected areas. (...)
Our analysis of divergence of microsatellites indicates that the tumor arose between 200 and 2500 years ago. Whether this time period represents the time the tumor first arose or whether it represents a later bottleneck in the tumor's dispersion as a parasite cannot be resolved. While this estimated date indicates a relatively recent evolutionary origin, CTVT represents the oldest known mammalian somatic cell in continuous propagation, having undergone countless mitoses and host-to-host transfers.

Okay, that's gross

WTF is a Roche Limit?

When you've given so many inkblot tests that you actually can see pictures in the inkblots?

Or is that a Rorschach Limit?

Nopez ;)

Hey Perfection, time for a new question

I'm out I open floor, as for Roche limit, wiki it foo', Perfy is too tired!

Ok, What's a histone, and what's is function in the bigger picture of things?

Is that the crap that binds DNA together Eukaryotic cells?

Well yes in the same way as the statosphere holding that junk that blocks UV light.

:)

Its arrangements expose certain sections of DNA to the cellular machinery. It's what allows a muscle cell to have the same DNA as a neuron, but only express the specific genes.

Correctomundo!

It's a class of proteins that bind DNA up into a mass of chromatin to make the chromosomes. The DNA wraps around the histones such that they would be an extremely long if the histones weren't there. They also appear to be modifiable and that appears to have a role in moderating gene express and DNA repair.

Histones are only found in eucaryotes.


Your turn.

What's the most evolutionarily divergent (from us) animal you can find which intentionally makes eye contact?

A crab of some sort?

What's the most evolutionarily divergent (from us) animal you can find which intentionally makes eye contact?

A fish of some sort would be my guess, because that way it is more viable evolution wise, I mean it can escape easier.

OK I've thought a little more, a mollusc, some sort of bicuspid? ;).

I would be amazed if you could find a source for crabs or bicuspids (you probably mean some type of mollusk, I assume) intentionally making eye contact. It would shake my world.
(as an adendum, the eye contact is cross-species, not merely intra-species)

I'll go with some kind of reptile, probably a lizard. Iguanas and some geckos have some wild-looking eyes. :)

Mr. Squid?

Mr. Bug?

Praying Mantis?

Is it some kind of mammilian predator?

Is it a trick question, like it's man!

Nah, cats look at you dead in the eye. That's why I'm thinking mammilian predator.

Nah, cats look at you dead in the eye. That's why I'm thinking mammilian predator.

Yeah but almost all animals look you dead in the eye when threatened. To a cat the most egregious insult you can pay it when it walks into a room is to look at it in the eye. This says to it, "I am threatened by your presence." The best posture you can adopt is to turn your back on the cat and barely acknowledge its existence, which is incidentally what cats do to you when you enter the room, which most people assume is being aloof, but is really the equivalent of saying, come on over bud, I am not threatened by you. You'll find that's why people who hate cats, who adopt a posture of shirking away and not looking them in the eye often get pestered, because they are sending out all the wrong signals.

Most animals will look you square in they eye when it is threatened, that makes sense, but what animal will do it as a matter of course and regardless? Cat's are a perfect example of an animal that would rather not look anything in the eye and will only do so when challenged or when making a challenge itself.

Dogs look people in the eye all the time. It helps them read our faces.

I don't know what animal El_Machinae is thinking of, but it's likely to be a social predator; predators have forward-facing eyes that they can focus on a specific point, and use vision especially. Social animals are more likely to use eye contact.

I'll go with some kind of reptile, probably a lizard. Iguanas and some geckos have some wild-looking eyes. :)
More divergent than that!
Mr. Squid?

Mr. Bug?
I haven't seen anything about Squid eye contact

And if you find something about bugs making intra-species eye contact, it would (again) change my view of that behaviour.
Is it some kind of mammilian predator?
MORE!

So far, Shee is the closest. Though 'predator' is a really good clue.

Having said that, do sharks make eye contact?

Some kinda bear?

Sharks it is! This month's Smithsonian has an article on Great Whites, and they've noticed that the shark will look people in the eye: when they're in the water or when they're on a boat. The theory is that eye-seeking behaviour evolved because mammals are a main prey for Great Whites (seals, iirc), and seal eyes are actually a decent source of information for the predator.

It's so distant that I can't help but think that it's a type of convergent evolution.

Eye-seeking behaviour is a fairly ancient pathway, and I believe that it's an essential component of an animal evolving "a Theory of Mind". Many animals are born with the instinct to seek out 'eye contact', which shows how deep it is in our brainstem. One of my pet theories is that autism is connected to a breakdown in the eye-seeking instinct, and thus it hurts the child's ability to form a Theory of Mind on an intuitive level.

Brighteye is up.

Can anyone tell me with what function the (pre)Botzinger complex is especially associated?

No ?

The answer I'm after involves a yes.

Can anyone tell me with what function the (pre)Botzinger complex is especially associated?

No ?

The answer I'm after involves a yes.

ok: yes then :p













for breathing - i.e. to generate your breathing rhythm - so that you don't have to remember to breath :evil:

It's where they generate insults for robots. Useful in apocalypse scenarios.
Bot-zingers.

for breathing - i.e. to generate your breathing rhythm - so that you don't have to remember to breath :evil:
That's the one. You're up.

name this little ursine fellow and tell me why some people believe it is the first known alien life form on earth :devil:

http://i218.photobucket.com/albums/cc314/ori_cfc/th_ursine.jpg (http://i218.photobucket.com/albums/cc314/ori_cfc/ursine.jpg)

Ah, so you downloaded the Spore Creature Creator demo, too. :p

Me too. That has to be some sort of mite. (http://en.wikipedia.org/wiki/Mite)
I doubt anyone on this board can ID one by sight though.

That's a water bear, I think.

No idea why it's alien though.

That's a water bear, I think.

No idea why it's alien though.

you are right in that it is a water bear. It does have some properties that make some people claim it traveled through outer space - what might those be :mischief:

Acid blood?

Acid blood?

:nope: that would be this fellow: :p

http://www.wam.umd.edu/%7Ekbrown14/pics/Alien1.jpg

Can I quote wikipedia in the interest of a new question? :)

He's extremely resistant to environmental stresses----temperature extremes, lack of atmosphere (total vacuum), and lack of water. The exact length of time he can go with out water is debated; Some cite only 10 years reliably, others extend that to a claim of a century. (Overall, a century is very irrelevant to space travel durations, so I doubt this guy hopped a comet between solar systems or something, though it'd be pretty neat if he could harvest the ice in a comet).

:gripe: why spoil a perfectly fine question with wikipedia? :nono:

anyway: sepamu92 is up - he got the water bear right :)

Who are these "some people"?

Who are these "some people"?

these people (http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=83425) - sorry I can only access the abstract...

They most clearly do not believe they are alien life forms!

:blush: I misunderstood you - should have had another :coffee: before typing...

some people would e.g. be this guy (http://sprott.physics.wisc.edu/PICKOVER/cliffphoto.htm) - as in this book (http://books.google.com/books?id=sedSiA2BNIcC&pg=PA169&lpg=PA169&dq=+tardigrades+alien&source=web&ots=FsS12gTb3D&sig=c9rNRBkxSHdfS9SE6xxY2talo-A&hl=en&sa=X&oi=book_result&resnum=1&ct=result) - though I would say it is a fringe view, makes good headlines though.

Those water bears are remarkable though in that they survive extreme temperature differences, pressure differences and differences in hydration...

Bah, I'm terrible at coming up with questions.

So what's the name of those super-fast-spinning neutron stars that like, flash light at us and junk?

Pulsars.90

Pulsars.90

YUP :)

Why was the first detected Pulsar dubbed the 'LGM' signal?

LGM = Little Green Man.

It was believed that such a regular pulse on radio frequencies was an indication of intelligent life trying to contact other intelligent life.

:blush: I misunderstood you - should have had another :coffee: before typing...

some people would e.g. be this guy (http://sprott.physics.wisc.edu/PICKOVER/cliffphoto.htm) - as in this book (http://books.google.com/books?id=sedSiA2BNIcC&pg=PA169&lpg=PA169&dq=+tardigrades+alien&source=web&ots=FsS12gTb3D&sig=c9rNRBkxSHdfS9SE6xxY2talo-A&hl=en&sa=X&oi=book_result&resnum=1&ct=result) - though I would say it is a fringe view, makes good headlines though.

Those water bears are remarkable though in that they survive extreme temperature differences, pressure differences and differences in hydration...You also seem to be misunderstanding Pickover. Pickover's "alien tardigrades" aren't literally tardigrades, but hypothetical creatures that would share its resiliance. He in no way implies that tardigrades are alien.

You also seem to be misunderstanding Pickover. Pickover's "alien tardigrades" aren't literally tardigrades, but hypothetical creatures that would share its resiliance. He in no way implies that tardigrades are alien.

:) I should be more careful in what I quote then - I misunderstood his stuff indeed - i.e. I lumped it in with a couple of tin-foil hat sites which I found. Probably was too quick to jump to conclusions there...
Actually the real source of this argument eludes me since I just remembered hearing/reading it in a description of their properties and when posting this question I just googled some queries and when I found what I thought was what I was looking for I asked :blush: I'll check my next question better :cool:

Edit: so it wasn't that fine a question after all - apologies to goodgame :blush: :please:

Are we up to 72 hours per questions? Ainwood got LGM right BTW.

Don't worry Ori, I have thick skin. :cool:
I could see those creatures being confabulated into a panspermia hypothesis, though without the evidence they hibernate for thousands of years or eat comet ice, that would be a very fringe hypothesis.

Anyone who would think that water bears are viable as either an alein creature or as a viable means of panspermia is out of thier gourd.

Water bears are animals with all of its evolutionary trappings, which means they evolved on Earth and thus are not aliens.

As a viable means of panspermia, water bears wouldn't work, because they (being animals) are heterotrophs, that is they can't turn inorganic matter into organic matter.

That and panspermia is not viable in the first place anyways.




Also, I second the going of Ainwood. He is correct.

For a multi-component mixture, what is the name give to the pressure above which no liquid can form?

Is it named after a scientist?

Critical Point?

Critical temperature?

:blush: Sorry, I thought it went without saying that Ainwood was correct. Didn't mean to bring the thread to a screeching halt.

No, its not named after a scientist.

Critical temperature is not correct.

Critical pressure?

No, its not critical pressure either.

Critical pressure & critical temperature are at the transition point between liquid & vapour (bubble point and dew point). This can actually be at a lower pressure than the maximum pressure at which liquids can form.

maximum critical pressure :mischief:

Is it not the critical point? After all, that is the point at which a substance's liquid and gas phases become indistinguishible, thus technically, no liquid can form.

Is it not the critical point? After all, that is the point at which a substance's liquid and gas phases become indistinguishible, thus technically, no liquid can form.
Yes, but you can have liquids at a slightly higher pressure, if its also colder.

Since it's a mixture, is it part of a binary phase diagram?

Since it's a mixture, is it part of a binary phase diagram?
Well, yes; it might not always be labelled, but with pressure on the ordinate axis, draw a horizontal line tangential to the phase diagram that just intersects at the highest point. The pressure at which it intersects the ordinate is the highest pressure at which a liquid can exist. It has a special name.

Liquid pressure apex :crazyeye:

I don't know either. Hope that helps. :)

Vapor pressure, unless you're talking about a specific model. Vapor pressure is the equilibrium pressure, below which, you tend to get liquid, and above which, you'll tend to get gas.

Vapour pressure is the pressure exerted by a liquid in equilibrium with vapour. In this case, there is no liquid, so the answer is not vapour pressure!

Is the assumption that this is a mixture of gases?

If yes then the question is really, what pressure will avoid condensation in a mixture of gases?

Its is a multicomponent mixture; not necessarily a mixture of gasses, because at some combination of pressure & temperature, there will be only liquid present. But there will be a maximum pressure above which there will be no liquid phase.

So Ainy, you compress this multicomponant stuff and it becomes all solid, right?

So solidification pressure?

Or does it become gas? That seems less likely to me, but I know jack about phase transition stuff.

Depending on the temperature, it becomes dense-phase (which for a single component system is analgous to super-critical).

On reflection, GoodGame's assertion that I am referring to gasses has some validity. I should stipulate that I am not referring to things like alloys. I am referring to multi-component mixtures in vapour-liquid equilibrium. I am talking about the phase diagram for such a mixture, and what the maximum pressure at which liquids can be present is called.

Its been 72 hours. Correct answer is cricondenbar. Equivalent for temperature (highest temperature above which liquids cannot be present) is cricondentherm.

Open floor.

What are the 10 largest (by volume) objects in the solar system (that we know of) in order from largest to smallest?

Oh and for mastermindish twist, I will state how many are on the list, and how many are in the correct position.

1. Sun
2. Jupiter
3. Saturn
4. Neptune
5. Uranus
6. Earth
7. Venus
8. Mars
9. Mercury
10. Xena (or whatever they decided to name it)

8 of the objects on your list should be on the list, 6 of the objects are in the correct order.

1. Sun
2. Jupiter
3. Saturn
4. Neptune
5. Uranus
6. Earth
7. Venus
8. Mars
9. Titan
10. Ganymede

I know it's two moons, because I was asked this back in grade 12 for some reason.

I think Titan's bigger than Venus, based on what Perf said ^^

History Buff:

10 of the objects on your list should be on the list, 6 of the objects are in the correct order.

Mise:

ANSWERS MUST BE IN LIST FORM :mad:

Fine!

1. Sun
2. Jupiter
3. Saturn
4. Neptune
5. Uranus
6. Earth
7. Titan
8. Venus
9. Ganymede
10. Mars

1.Perfection's Ego
2.Sun
3. Jupiter
4. Saturn
5. Neptune
6. Uranus
7. Earth
8. Titan
9. Venus
10. Ganymede

Ohh, for starters, Uranus is definitely bigger than Neptune. As for what else is out of order, it's gotta be the last 2.

0. Perfy's ego
1. Sun
2. Jupiter
3. Saturn
4. Uranus
5. Neptune
6. Earth
7. Venus
8. Mars
9. Ganymede
10. Titan

Bingo Bango, Buffy :goodjob:

Bingo Bango, Buffy :goodjob:

The vacuum is the largest (if you can call it an object)


You should have said 'by mass', not by volume.

The vacuum is the largest (if you can call it an object) I don't think you can. I suppose compact body would be a better term, though.

You should have said 'by mass', not by volume.
Why?

Why?
Because the volume of the solar system is much larger than the volume of the bodies within it.

Yeah, well everyone figured it out so :p and :hammer: and :smug:

And really, mass wouldn't prevent all the issues, because pedanticites coulda said crap like Kuiper belt and whatnot.

The key here is the implicit understanding that object means compact body that everybody figured out.

Alright, here we go:

In a very basic way, how do GPS receivers estimate the effect of atmospheric interference on the recieved signal?

Some kind of correction based on local meteorological reports?

Using math?

Do the satellites send out a "signal" signal (...something like a single-frequency, standard amplitude signal, at standard intervals in time, outside of the frequency range of the "data" signal) that is known to the GPS receiver? Any deviation from this known signal (noise, assumed to be as a result of atmospheric interference) can be used to estimate the effect of atmospheric interference.

Is it that when a GPS powers up, it sends a signal to a single geostationary satellite which sends a signal right back, which should take a fair precise time. If the atmosphere is denser because of interference and such, the signal is delayed and the density of the atmosphere calculated using the Beer-Lambert relationship?

Is it that when a GPS powers up, it sends a signal to a single geostationary satellite which sends a signal right back, which should take a fair precise time. If the atmosphere is denser because of interference and such, the signal is delayed and the density of the atmosphere calculated using the Beer-Lambert relationship?

GPS receivers don't broadcast (or more properly, GPS satellites don't listen for recievers).

Do the satellites send out a "signal" signal (...something like a single-frequency, standard amplitude signal, at standard intervals in time, outside of the frequency range of the "data" signal) that is known to the GPS receiver? Any deviation from this known signal (noise, assumed to be as a result of atmospheric interference) can be used to estimate the effect of atmospheric interference.

This is on the right track, you've got the technique in here.

Specifically though, how do they isolate atmospheric interference without solving for things like clock-error in the reciever?

They do it by sending out signals at a set frequency (time between pulses). Atmospheric interference will not affect all pulses equally, so by looking at the time difference between a number of pulses, the atmospheric effects can be determined.

They do it by sending out signals at a set frequency (time between pulses). Atmospheric interference will not affect all pulses equally, so by looking at the time difference between a number of pulses, the atmospheric effects can be determined.


Also the right idea, but you work out the difference between something slightly different.

EDIT: Just to be extra specific about it, I mean the Ionospheric component of atmospheric interference, when doing single point positioning. And that doesn't eliminate any previous answer.

Alright, that's 72 hours.

You do it by using two different frequencies. GPS satellites broadcast on two different channels, called L1 and L2. Because the Ionosphere affects the two frequencies differently, you can use that and a whole lot of math to get a pretty good idea of how active the Ionosphere is, and how much its delaying (or advancing, which does happen) your signal.



Easy one this time:

How many GPS satellites do you need to see in order to get a valid position fix, and why?

How many GPS satellites do you need to see in order to get a valid position fix, and why?

Four: One for every dimension. Your postion has three degrees of freedom, so you need three signals to fix it. The forth is needed to fix the time (the forth degree of freedom in space-time)

Four: One for every dimension. Your postion has three degrees of freedom, so you need three signals to fix it. The forth is needed to fix the time (the forth degree of freedom in space-time)

Bingo. Your turn.

Under what conditions can an object levitate in a static magnetic field?

We had that question before, btw ^^ (History buff's second question that is).

@uppi: if it's spinning?

We had that question before, btw ^^ (History buff's second question that is).

@uppi: if it's spinning?

No, it doesn't have to spin. Spinning might stabilize it, but I don't think it helps in the levitation part.

Hint: To levitate the object needs a certain property.

We had that question before, btw ^^ (History buff's second question that is).

@uppi: if it's spinning?

I figured you might have. I just love it because most people will say 3 without thinking. And this was slightly better than leaving an open floor.

If the object is itself magnetic or has a magnetic field from an electric current going through it.

If the object is itself magnetic or has a magnetic field from an electric current going through it.

No. There is no stable equilibrium for two magnets (or a magnet in a magnetic field), only unstable ones. There are some tricks to stabilize it, but that's not my question.

Another hint: Water can levitate.

EDIT: nevermind...

It needs to be frozen I believe, or at least at very low temperatures.

It's hoverin' over a superconductor.

It needs to be frozen I believe, or at least at very low temperatures.

No, depending on the material it can also work at room temperature. (It is way easier to get a sufficient magnetic field at very low temperatures, though)


It's hoverin' over a superconductor.


Superconductors can levitate very easily, as they are a perfect example of the needed property. But they're only a special case, it works with other materials, too.

Induction!

So I assume you need a field and a current?
A flow of electrons?

Induction!
Induction only works if something is moving. In the case of levitation there isn't anything moving (at least not down, and you would need that for an upward force)

So I assume you need a field and a current?
A flow of electrons?

You need a field, but there is no need for a current (apart from the current needed to generate the field). The right object has to be at the right place, but nothing else is needed.

I know I can't win, but based purely on your water comment, does it involve molecular polarity of the substance in question?

I know I can't win, but based purely on your water comment, does it involve molecular polarity of the substance in question?

About to answer with "polarity".

You took my answer! :cry:

No, polarity isn't involved. Polarity is an electric characteristic, I am looking for a magnetic characteristic.

Ferromagnetism?

Ferromagnetism?

No, but we're slowly getting there.

Paramagnetism?

Diamagnetism?

Diamagnetism?

Yes, that's it. For something to levitate in a magnetic field it has to be diamagnetic. If a dimagnetic object is placed in a strong enough inhomogenous field at the right place it can levitate.

Superconductors can be seen as "perfect diamagnets", that's why it's easy to get them to levitate.

Water is also diamagnetic, so it is possible to manage levitation with things that are mostly water.
These guys (http://www.hfml.ru.nl/levitation-movies.html) have made videos of a frog and a strawberry and other things levitating.

Your turn.

Geez, and I can't even remember what those words mean. :lol:

In what phase of matter can a material be 'smectic' or 'nematic'?

Plasma?

XCL

Liquid????????????????????

Bose-Einstein Condensate!

I love multiple choice.

No, no and no!

GAS

perhaps?

'Fraid not. :D

Fermionic condensate? /randomguessing

I can't believe no one's said 'Solid' yet...

SOLID!!!!!

e

:p Nope. :lol:

That other phase of matter?

Trick question! You made those words up. :mad:

:p Nope. :lol:
You bastard :p :lol:

You guys are gonna kick yourselves when I tell you...

Yes, that's it. For something to levitate in a magnetic field it has to be diamagnetic. If a dimagnetic object is placed in a strong enough inhomogenous field at the right place it can levitate.

Superconductors can be seen as "perfect diamagnets", that's why it's easy to get them to levitate.

Water is also diamagnetic, so it is possible to manage levitation with things that are mostly water.
These guys (http://www.hfml.ru.nl/levitation-movies.html) have made videos of a frog and a strawberry and other things levitating.

Your turn.

I visited that lab, and it's at the university I'll be studying next year :cool:

You guys are gonna kick yourselves when I tell you...

I looked it up. That's dirty :p

Give us a clue!

Chances are you're looking at some right now...

I'm looking at a picture of two rabbits fighting. Is that in any way close to being the answer?

It depends on your monitor...

Liquid crystal?

BINGO!

Smectic and nematic types are variations in the amount & type of molecular ordering present within liquid crystals. There are others too.

Your turn.

I'm looking at a picture of two rabbits fighting. Is that in any way close to being the answer?Are they These (http://www.youtube.com/watch?v=ybVb3t560oY) Rabbits?

In the absence of reply from that nice Mr Nonconformist, I suggest we go to open floor.

I thought I'd got it wrong again....
open flooooooooooooor

What does M-mode of an ultrasound machine do?

Ok I'll admit, I used wikipedia so I'll post the answer in a spoiler:

M stands for motion, it enables to see motion

it allows the depiction of motion within the examined tissue. more exactly it depicts the depth in the x-axis and time in the y-axis so that the examiner can discern movement of surfaces within the beam.

it allows the depiction of motion within the examined tissue. more exactly it depicts the depth in the x-axis and time in the y-axis so that the examiner can discern movement of surfaces within the beam.

Quite so: your question.

ok this is again more history of science:

explain Charles Darwin's theory of Pangenesis :)

Never heard of it. :)

Never heard of it. :)
for some reason it is not his most famous work :mischief:

Who is this 'Charles Darwin' anyway????

ok this is again more history of science:

explain Charles Darwin's theory of Pangenesis :)

Based purely on the roots of the word, it's a theory that every living species descends from one common ancestor, who's various members branched out and evolved into different things.

No .

Does it involve abiogenesis somehow?????

They started out as pots and slowly became flatter with longer handles?

The wikipedia equates it with Lamarckism, which is mostly considered an intellectual dead-end in evolution theory. I've never heard of pangenesis to this question, so I'd say it's even a deader dead-end. Basically a wild hypothesis gone looking for some facts.

Does it involve abiogenesis somehow?????
no - it does not concern the way life started, but a way of how it might evolve...

They started out as pots and slowly became flatter with longer handles?
:p

The wikipedia equates it with Lamarckism, which is mostly considered an intellectual dead-end in evolution theory. I've never heard of pangenesis to this question, so I'd say it's even a deader dead-end. Basically a wild hypothesis gone looking for some facts.

That is the right track - though don't discount Lamarck too much, with the discovery of epigenetics his theories while in essence wrong have been shown to have some truth after all...
Essentially what I am looking for is how Darwin proposed how inheritance works - it was one of the centerpieces of his theory after all - and he did propose a way that would have been (and was at the time) acceptable to Lamarckians...
And while Darwin was wrong his theory inspired later (Mendelian) scientists to coin the words pangenes which then became genes to describe those discrete determinants of inheritance they were observing - as I said it really is history of science - not a current theory...

If no one answers this today I'll switch to something more current though ;)

If the mummy has a survival trait that the daddy lacks, the survival trait is inherited by ALL offspring? (In contrast with Mendelian inheritance, with its dominant and recessive traits 'n' all that jazz.) Lamarckians would accept this because, in their view, the survival trait needs to be deemed "beneficial" by something, therefore it doesn't go against Lamarckism. It doesn't go against Darwinism because Darwin would have classified it as "some additional evolutionary trait", over and above the "standard" set of traits a species already has, and therefore it doesn't need some arbiter of "beneficial-ness" for it to work.

Darwin believed in 'genetic blending' IIRC (so if one dog has a long tail, and another one has a short tail, the offspring will have a medium-sized tail, according to Darwin). Is that what 'pangenesis' is?

Darwin believed in 'genetic blending' IIRC (so if one dog has a long tail, and another one has a short tail, the offspring will have a medium-sized tail, according to Darwin). Is that what 'pangenesis' is?

this is the outcome of it - so you are right.

pangenesis was his theory that all cells of an organism shed "gemmules" that accumulate in the reproductive organs and combine during fertilization - thus blending the makeup of both parents to form the offspring...

Hey now, this is post #991. Whoever gets this one right should probably start the new thread...

What is a 'Messier marathon'?

Typing an 'eleven' more than a couple of times while doing a string of exclamation marks.

!!!!!!!!!!!!!!11!!!!!!!!!!!!!!!11!!!11!!!!!11!!11! !!!!!!!!!!!!!!!!!!!!!!!!!!11

Is Messier a scientist?

I think Messier discovered comets or something. So something to do with them?

For some reason that makes me think of 'random walk' mathematics. Is it something to do with displacements in brownian motion or some such?

*Utter total stab in dark*

Is Messier a scientist?

Shoot, I was thinking of the hockey player.

An attempt to find a lot of Messier objects in 1 night (of the 110 cataloged by him) usually amateur in nature involving a bunch of people? (if right thanks im going to thank my dad for that Astronomy course)

Civ_King is correct!

In a Messier marathon, you attempt to find all of the 110 Messier objects (or as many as possible) in one night. There's a window of time in the year when finding all 110 is possible.

(EDIT: Do threads get closed at 1000 posts in Sci/Tech? If so, civ_king can probably start a new thread. :D)

New Thread Time! :dance: :banana:

We close at 1000. Well willya lookit that. :)

Start new thread CivKing.