solar system - Could the 9th planet be virtual?

The ninth planet can absolutely be a "virtual", in the way you describe it, meaning observed data indicating the gravitational influence by an object is not actually caused by such an object.

A simple visualisation of this is the case of a two-body system, where we observe two objects orbiting a common barycentre. From the observed data, one can get the impression that there is an object in the barycentre, pulling both of your observed objects against it.¹

However, a barycentric way to explain the observations gets less likely as you add more bodies. Be aware that the current indications of "planet 9" is based on a mere correlation of some not-so-accurate data, from a small sample size, heavily biased by observation constraints.

how could we distinguish a "real" 9th planet from a virtual one,
except by the obvious answer if we can observe it directly?

That is only by its gravitational influence alone.

As a rule of thumb, incomplete and inaccurate data always imply the risk of causing virtual objects.

It should also be noted too that observations in the Kuiper belt generally can not yield how a orbit changes, due to the extremely long revolution times. observing "Interactions" are actually mostly about tracing an orbit back from its current state vectors, to find probable interaction events in the past. That is literary to ask for data artefacts and virtual objects.

¹Before anyone objects about how easy it is to falsify that: Yes it is easy to determine that there can not actually be an object there, based purely on observing the two bodies. But, that requires 1. accurate data about the motion of the two objects, and 2. their mass. Our current data about the Kuiper belt fails to give good enough data on both points.

psychology - Is kissing a natural human activity?

Wikipedia actually has a note on the evolution of kissing. They point out that there are grooming behaviors such as licking and social behaviors like dogs touching noses in many species even insects. They note that it is not decided at all whether kissing is learned or from some sort of instinct. They also mention that its reminiscent of feeding behavior common in birds (and other animals) where food is pushed down the throats of young. (try thinking about that next time!)

I seem to remember though that there are some culture which do not kiss. with their lips at least. This would favor kissing as a learned behavior, but these cases are very rare and isolated peoples and it might be simply a taboo to talk about kissing with researchers or at all, which is a hazard of that sort of work. In addition, bonobos, one our our closest primate cousins, do kiss frequently with the lips, as a social and intimate gesture and the parallels with most human cultures are difficult to ignore.

natural satellites - Why does Saturn have both moons and rings?

From my understanding, a ring can form around a planet when a moon gets too close to its Roche limit, and gets ripped appart by the planet's gravity pull. That makes sense to me, but I don't understand why Saturn has both moons and rings at the same place.

I know the F ring is supposedly created by Enceladus' rejections, but I don't get why Pandora and Prometheus are not ripped appart as well as the ancient objects that formed the ring they are in.

I couldn't find specific explanations for this. Does it have any link to the moon's density?

molecular biology - Purpose of poly(A)+ RNA?

I am learning RNA-seq analysis. I always encounter this phase "poly(A)+ RNA". After searching, I got this: "Most messenger RNAs contain a poly(A) tail, while structural RNAs do not. Poly(A) selection therefore enriches for messenger RNA. The technique has proved essential for construction of cDNA libraries."

Does it mean that when constructing the cDNA, we always use the ones with a A's tail? Then other RNAs like tRNA are filtered and not used to get their cDNA? I do find some RNAs records on UCSC where microRNAs are included.

When we say poly(A)+ RNA library, what is the difference between normal one? Or normal RNA library is a poly(A)+ RNA library? Thanks.

orbit - What if Earth and Moon revolved around each other like Pluto and Charon?

TLDr answer:

Both answers are very good. There's a few more details to consider if we want to look at all the what-ifs in this amusing but wacky scenario.

Already mentioned, the ratio of size is 8 to 1, not 81 to 1, so for starters, the Charon like Moon would be much larger in the sky. The Moon, with roughly 10 times the mass, figuring slightly greater density due to some minor compacting, would still be 2.1 times as big across, assuming the same distance, that would make it 4 times as bright in the night sky. A full moon would be quite impressive. Perhaps (just barely) bright enough to read by if it was a large text book. (some people claim to be able to read by Moonlight now, most people can't, but 4 times brighter, a full moon might just be bright enough.

Solar eclipses would become more frequent and last about twice as long and you might think the Earth would be slightly colder due to the Moon blocking some sunlight, but the Moon, believe it or not, radiates more heat on the earth than it blocks because the lit up moon that faces us is nearly 400 degrees F in peak daytime and it's not hard to see that a surface that temperature radiates some heat. Not a lot, but some. A question on that here, so a little over 4 times the energy (ignoring solar eclipse losses), about 1/2,500th the heat from the sun, might work out to 1/10th of a degree at night during a full moon. Not a lot, certainly, but measurable to anyone with sensitive enough instruments. The brightness and size of the Moon would obviously be more noticeable than about 1/10th of 1 degree in temperature (C not F).

A moon of that mass would slow down the Earth's rotation significantly faster, already mentioned, but this one, we have to give some thought to. When the Moon formed it was much closer to the Earth, about 3-5 times the radius of the Earth away. Source. That's outside the Hill Sphere, and the formation of the Moon left the Earth rotating very rapidly so the effects (rapidly rotating earth, very powerful lunar tides) would still be there but the Lunar tides would be 10 times greater, so we're looking at earth-quake level tides when the moon, 10 times the mass, was 3-5 earth radius away. The Moon, because during formation it wouldn't have much angular momentum, would quickly settle into a tidally locked rotation around the Earth. The Tidal effect on the Earth, being 10 times greater would cause (roughly) 10 times the tidal bulge on the Earth would would push the Moon away from the Earth about 10 times faster, but, at the same time, the tidal drag slowing down the Earth, would be 10 times as great too (I assume that corresponds to about 10 times as fast).

So, basically, the Moon and Earth would follow the system they're in now, but it would proceed about 10 times as fast with a Moon with 10 times the mass. The estimate (here) is that it will take about 50 billion years for the Moon to slow down the Earth enough to enter into tidal locking, so divide that by 10, we would be very close to a tidal lock today. The Earth would rotate very slowly. The moon would also (likely) be a bit further from the Earth and probably have a more wobbly orbit due to solar perturbations, and perhaps, escaped completely. This is a complicated bit of mathematics that I'd prefer not to attempt (at the Moon's current mass, the Sun will go Red Giant long before either the Moon escapes or the Earth gets tidally locked but with a Moon 10 times as massive, that's probably no longer the case and either the Moon is gone or the Moon is more distant, has a more elongated orbit, and the Earth is at or close to tidally locked. If the Moon escapes, we'd have a near earth orbit object of enormous size that could later crash into us or swing past the earth and move our orbit - either effect and simply the effect of having no moon, would be enormous.

Discussion on the Moon/earth escape vs tidal locking here

If we assume full tidal locking, 29.5 days (synodic, not sidreal) and a moon a bit further out so we might be looking at 30 something to maybe 40 days for 1 earth rotation, that's 20 days of sunshine, 20 days of night. That would play absolute havoc on the weather systems and seasons. Day to night would have a bigger effect than Summer vs winter, and the summer days would be scorching, though some regions might due just fine because of rainfall. Evolution could probably adapt to that, but it doesn't sound fun to me. The further distance might make the Moon just 3 times as bright in the night sky instead of 4. still pretty bright though. You'd still get 6 months of sun and 6 months of night at the poles, but for most of the earth, this would be a radical change having days and nights that long.

Other possible effects, Obliquity (no moon, perhaps greater, a larger ice age driver), see here. Also, if the Earth still had the Moon but the Moon was in a more elongated orbit, we'd still have tides as the Moon moved in and out to appogee and perogee. see picture

Source

The bottom line, while we might not give it much thought, a different sized moon would actually change quite a lot. A smaller moon would move away from the Earth more slowly and earth might be able to have a 2nd moons perhaps by capture, if the moon was smaller, also we might have more aggressive ice ages and climate changes due to a greater obliquity variation and, assuming the giant impact still happens in a similar way but a smaller amount of debris (which doesn't make sense, but lets pretend), then a smaller moon wouldn't have slowed the Earth's rotation as much and the Earth might be rotating quite a bit faster, 10 or 15 hour days instead of 24. The effects would be pretty significant.

entomology - Why don't dragonflies wings collapse?

Wootton (1992) reviewed the anatomy and biomechanics of insect wings. Basically the wing is a lightweight but strong scaffolding of veins, supporting a thin membrane. The veins are composed by a sandwich of cuticle with a potential space in between. The membrane is also a double-layer but without the space.

In the venous space are is circulating hemolymph and often nerves and tracheae. The wikipedia image is pretty good:

The nerves carry sensory information and the tracheae oxygen.The hemolymph is continuous with the body and thus is able to circulate and hydrate the wing (important for maintaining flexibility). As Wootton says:

desiccation destroys both compliancy and toughness, and a dry cuticle would be mechanically disastrous

So by maintaining a flexible tissue, insects have strong and tough wings that remain light enough.

How do scientists know there are about 300 billion stars in a galaxy and there are about 100 billion galaxies?

The way it works is as follows. We do detailed studies of stars in the solar neighbourhood. This establishes the local density of stars and the mix of masses they possess (called the stellar mass function). We compare that with the mass function of clusters of stars and note that to first order it appears invariant.

We can then triangulate the problem in various ways: we can make a model for the stellar density of the Galaxy, assume it all has the same mass function and hence get a number of stars. The model may be based on crude light-to-mass conversions, but more often would be based on deep surveys of the sky - either narrow pencil beam surveys from HST, or broader surveys like SDSS, The key is to be able to count stars but also estimate how far away they are. This is highly uncertain and relies on some assumptions about symmetry to cover regions of our Galaxy we cannot probe.

Another method is to count up bright objects that might act as tracers of the underlying stellar population (eg red giants), compare that with the number of giants in our well-studied locale, and from this extrapolate to a total number of stars, again relying on symmetry arguments for those bits of the Galaxy that are distant or obscured by dust.

A third way is to ask, how many stars have lived and died in order to enrich the interstellar medium with heavy elements (a.k.a. metals). For example, it turns out there must have been about a billion core-collapse supernovae to create all the oxygen we see. If we assume the mass function is invariant with time and that supernovae arise from stars above 8 solar masses, then we also know how many long-lived low-mass stars were born with their high-mass siblings and hence estimate how many stars exist today.

The number, whether it be 100 billion or 300 billion is no more accurate than a factor of a few, but probably more accurate than an order of magnitude. The main issue is that the most common stars in the Galaxy are faint M dwarfs,that contribute very little light or mass to the Galaxy, so we really are relying on an extrapolation of our local knowledge of these objects.

The number of galaxies problem is easier, though the number is less well defined. We assume that on large scales the universe is homogeneous and isotropic. We count up how many galaxies we can see in a particular area, multiply it up to cover the whole sky. The number must then be corrected for distant faint galaxies that cannot be seen. The difficult here is that we are looking into the past and the number of galaxies may not be conserved, either through evolution or mergers. So we have to try and come up with a statement like "there are n galaxies in the observable universe today that are more luminous than L". I think this number is certainly only an order of magnitude estimate.

jupiter - Astronomy Calculations Tool

I took many images like the following:

As many of you may recognise, this is a picture of Jupiter and its four Galilean moons. Using these images, I am aiming to calculate the mass of Jupiter by finding the orbital distance and orbital period of each of these moons, and then plugging those values into Kepler's Third Law.

However, this requires a seemingly tedious process of the following sort:

1) Locate the centre of mass of Jupiter

2) Measure the distance to each of the planets

I have a lot of data (many, many pictures). I am hoping that there is a relatively easier (or even more accurate) method of doing all of the above than using software like Gimp to do everything for each image manually. Can anyone recommend anything?

transcription - Bacterial chromatin binding data?

A large number of prokaryotes do indeed have nucleosome-like structures. The most well studied is H-NS in E. coli, Salmonella and some other deltaproteobacteria. H-NS like molecules have also been found in mycoplasma (Lsr2). One of its roles is to bind AT-rich DNA and silence transcription. The binding is usually to suppress the expression of foreign DNA which tends to have a lower GC content than the host organism. There is a great paper that did ChIP on ChIP with H-NS in Salmonella by Navarre et al in Science (Pubmed ID: 1676311).

As a side note H-NS does compact DNA and there is a paper by Dame et al. that demonstrates it with atomic force microscopy.

epidemiology - Why doesn't yearly screening for lung cancer decrease mortality rates?

There are a number of reasons, generally, why a screening test may fail to decrease cancer mortality rates:

1. The screening test may not be very good. I know this seems like an obvious one, but its something of a problem - a screening test will only reduce mortality if it catches cases that are both treatable and wouldn't be detected in time to treat using other methods. For example, it may be that even if caught slightly later by other methods, lung cancer is equally treatable (or equally difficult to treat).


2. Mortality from false positive tests and subsequent procedures in non-cases offsets any gain in survival among cases.


3. Diagnosis is only one step toward treating a disease. Even if detected, if a disease is not treatable or isn't treated, knowing you have the disease doesn't change your mortality risk.

In this case it appears that a chest radiograph isn't good enough at detecting lung cancer to manifestly improve mortality outcomes. The author's of the paper don't really specify why this is - though since they're just looking at lung cancer mortality, it's likely not #2.

Is dark matter influenced by gravity of baryonic matter?

Dark matter attracts baryons not only by a "kind of gravity", but simply by gravity. Everything that has mass (even if it's only relativistic mass like light) attracts everything else by gravity, and thus baryons also attract dark matter.

The reason dark matter "organizes" galaxies is just that there is much more of it, roughly 7 times more, to be specific. So, on large scales, the dynamics of galaxies are dominated by dark matter. But because baryons can dissipate energy, it may collapse in clumps — such as molecular clouds — which are hence dominated by baryons.

the sun - Is the Sun really a medium size star?

It is true that a surprisingly large number of stars are smaller (and thus less massive) than the Sun. However, the stars that are bigger than the Sun are often much bigger.

Look at this chart:

^{Image courtesy of Wikipedia user Jcpag2012 under the Creative Commons Attribution-Share Alike 3.0 Unported license.}

Notice how small the Sun is compared to some of the other stars. It's tiny! It is indeed a small star - in technical terms a main sequence dwarf.

However, despite its size, it is clear that there are many more stars less massive than the Sun that there are stars more massive than the Sun. Why? There are two reasons:

1. Lower-mass stars live longer.


2. More low-mass stars can form in a given region than high-mass stars.

^{Encyclopedia of Astronomy and Astrophysics}

The distribution of masses can be quantified in an initial mass function, typically given in the form
$$xi(m)=km^{-alpha}$$

When you integrate this over a range of masses, you can find how many stars are within that range. Not surprisingly, this number gets lower and lower as you slide the endpoints to more massive stars. You can see this decrease from the fact that $xi'(m)<0$, so long as $k>0$ and $alpha>0$ - which is assumed by the model, according to empirical data.

Number of stars & planets in Milky Way Galaxy?

A consensus number is that there roughly $10^{11}$ stars in our Galaxy (though this number is certainly uncertain by a factor of at least two, because it is based on extrapolating what we know about stellar populations in our vicinity). Most of these stars are of lower mass and are much less luminous than the Sun.

The number of planets is even more uncertain. It now seems probable that most stars like the Sun have at least one planet, but we really don't know that much about the diversity of planetary systems, how typical something like the solar system is, or how planetary systems might change as a function of position in the Galaxy. We also don't know that much about planetary systems around the dominant (by number) very low-mass stars. They certainly can have planetary systems, but the fraction that do is still a work in progress.

zoology - How do baby animals that primarily subsist on cellulose get their initial gut flora?

In the case of mammals like giraffes and koalas, is that bacteria common on the plants they eat so when a baby starts to try to stick something besides its mother's milk in its mouth, it can't digest the cellulose at all the first time, but along with the cellulose, into its mouth went some cellulose-digesting flora that then begins a lifelong colony in the animal's gut? Is that about how it happens?

evolution - Computational/mathematical models for predicting phenotype from genotype

The Karr et al. paper attempts to capture most of the details in their model by combining features from the genome, transcriptome, proteome, and metabolome. This work heavily builds off of the coarse-grained models that you ask of especially on the work from Bernhard Palsson from which Markus Covert did his training. The answer to your question rests entirely on the type of question that you seek and what you want the model to do.

For the most part, most of your questions can be answered using COBRA, the COnstratins Based Reconstruction and Analysis Toolbox. You can get a good idea of what genotypes can be knocked out and see how it affects the phenotype as long as the phenotype is a known pathway that gets affected by that gene and you don't care about temporal and dynamic information.

There is also the E-Cell Project for E. coli. I personally don't know much about it but it has created some basic models for E. coli and that may be good enough.

If you want to build your own models, you should check out BiGG where all of the large-scale reconstructions exists. A good chunk of the code is stored at the Palsson lab website where you can attempt to use COBRA and start generating your own hypotheses.

star - A black hole that doesn't take in matter?

This is the full quote

If, for example, the Sun were replaced by a black hole of equal mass,
the orbits of the planets would be essentially unaffected. A black
hole can act like a "cosmic vacuum cleaner" and pull a substantial
inflow of matter, but only if the star it forms from is already having
a similar effect on surrounding matter

It's badly written, but what it's basically saying is that it doesn't matter the form of the massive object that's being orbited by a planet or other object. A stable orbit would remain stable, so, if our sun was to collapse into a black hole and nothing else changes, Earth's orbit would remain the same. It would get dark and cold, but the orbit would be unchanged.

The misconception is, if the sun became a black hole than Earth would be sucked into the sun. That's 100% false and that's all they're saying.

Gravity is a function of mass and distance. Black holes have very high gravity, but a big part of the reason for that is because when they form out of dying stars, they become very small, a few solar masses squeezed into only about 10 miles across so the distance to the center of mass gets very small.

For a planet to be in any danger from a black hole, it would probably need to be inside the Roche Limit, perhaps only a few million miles away, which is several times closer than Mercury is to the sun, for example. The safe distance, of-course, varies with the density and solidity of the orbiting object.

Here's a Q on Roche Limits and Black holes if interested.

structural biology - What is the distance between the 3' 18s rRNA (the Kozak consensus sequence) and the A-site of eukaryotic ribosomes during protein translation?

Kozak consensus sequence (KCS) is present near or overlapping with the start codon. I am not sure what you mean by distance between that and A-site. Start codon is localaized at P-site at the time of translation initiation. Distance between start codon/KCS and A-site at initiation is same as distance between P- and A- sites (I guess ~20Å). A-site keeps moving during translation and hence the distance keeps increasing. Crystal study is available; See here.

See this figure from the abovementioned study for the relative positions of start-codon, P-site (exit) and A-site (entry).

                    

How can we focus radio telescopes on a star when the earth is spinning?

There are two processes to manage this:

First, the telescopes (really, big antennas) are aimed mechanically and move so they can maintain their reception of a specific star/source/sky location over time.

However, except for stars immediately in the vicinity of the pole stars, the star will eventually go below the horizon. Once this happens the telescope/antenna cannot receive anything further until the source appears above the horizon again.

What happens at this point is we have many telescopes/antennas around the world that are collectively controlled. Long before a star/source/etc falls below the horizon for one telescope, another telescope further west has already pointed at it, and is receiving the same signal. Once this switchover has occurred, the previous telescope is free to select another target - something else on the other side of the planet that will be falling below the horizon for telescope further east.

In this way:

• The telescopes are under constant use pointing at interesting things


• Things which need continuous monitoring can be monitored without interruption despite the world turning


• We can observe anything at any time, as long as there's available time on the radio telescope network


• Sharing resources allows scientists to conduct science more completely and inexpensively


• By having 2 or more telescopes pointing at the same object at once, we can effectively increase the signal to noise ratio and get better data - it's technically very similar to having one earth sized single antenna rather than two tiny (relatively) antennas.


• With central control of a whole participating worldwide network, scientists can react very quickly to sudden phenomena, like bursts, at any time, regardless of the position of the earth

life - Red dwarf variation in Luminosity

The creator seems to be referring to flare stars. Flares may be magnetic in origin, like various manifestations of the Sun's magnetic field. These flares can be quit luminous across the electromagnetic spectrum, including in the x-ray wavelengths.

Some red dwarfs are flare stars, though flare activity may be largely restricted to a small part of a red dwarf's lifetime. However, during this period, life on a planet orbiting close to a red dwarf could be in serious danger.

The reference to convection may be that red dwarfs are generally fully convective, unlike other stars. Magnetic fields in stars are generated via the dynamo effect; in red dwarfs, full convectivity can play a huge role in generating strong magnetic fields, and thus stellar flares.

big bang theory - Why can we still see 10 billion year old galaxies?

We can't see how those galaxies look right now. If a galaxy appears to be 10 billion light years away, that also means that the light took 10 billion years to reach us. It's a bit confusing that "distance" and "time" are sometimes the same thing in astronomy.

So the light which the galaxies emit today (if they still exist) will reach us in another 10 billion years. What we see right now is light that was emitted 10 billion years in the past.

This also means that by looking at the farthest possible distance, we can see light which was created shortly after the big bang. One such source of light is the ubiquitous background radiation which was probably created by the big bang itself. It's easy to see because it fills all the gaps between the celestial objects.

Unfortunately, this also means that we always get an "outdated" view of the universe. If aliens started to blowing stars at the far side of our galaxy, it would take us 100'000 years to see the light.

Gas halo of our Milky Way Galaxy

The scale height of gas in a disk (if it were in equilibrium) is roughly $kT/mg$, where $T$ is the temperature, $g$ is the gravitational field, $m$ the mean mass of agas particle, and $k$ the Boltzmann constant.

If we assume most of the mass is in a thin disk, then Gauss's law for gravitation tells us that that $g = 2pi G sigma$, where $sigma$ is the mass per unit area in the disk. According to Rix & Bovy, $sigma simeq 70 M_{odot}$ pc$^{-2}$ at the location of the Sun (http://arxiv.org/abs/1309.0809).

If we assume hydrogen gas, then the effective particle mass is that of a proton, and this means the gas scale height is
$$ H = 4300 left(frac{T}{10^6 K}right) pc$$

Thus gas hotter than a million degrees will have a very substantial scale height and is not expected to be confined to the Milky Way disk.

dna isolation - Why is proteinase K digestion performed at 50 °C?

Proteinase K activity is greatly increased by addition of denaturing agents like SDS or urea (Hilz et al., 2008), indicating that the denaturation of the substrates helps Proteinase K to degrade them.

Increasing the temperature to 50°C will also unfold some proteins already, making it easier for the Proteinase K to degrade them. The proteinase K seems to be a pretty stable enzyme, and can still work at this temperature.

comets - Earth's Versus Catastrophic Meteor

How evasive is the Earth to Catastrophic Meteors?

Google says the Earth is approximately 92.96 million miles from the Sun. It also says the suns radius is 432,474 miles.

Therefore, it is 93,392,474 miles from the Earth to the center of the Sun:

92,960,000 + 432,474 = 93,392,474 miles

I've heard the Earth's orbit is elliptical, but to keep things simple, let's just say the orbit is a perfect circle. Therefore the radius of this circle is 93,392,474 miles. This would mean the diameter of our orbit would be 186,784,948 miles:

93,392,474 x 2 = 186,784,948 miles

The circumference of a circle is π x the diameter of a circle. Therefore, the number of miles in Earth's orbit would be about 586,504,736.72 miles:

3.14 x 186,784,948 = 586,504,736.72 miles

So, the Earth travels about 586,504,736.72 miles in one year. Since there are 365 days in year, that would mean that Earth travels about 1,606,862 miles in one day.

586,504,736.72 ÷ 365 = 1,606,862.292383562

That would mean the Earth travels about 66,953 miles per hour:

1,606,862.292383562 ÷ 24 = 66952.595515982

And this would mean the Earth travels about 1,116 miles per minute:

66952.595515982 ÷ 60 = 1115.876591933

Lastly, this would mean the Earth travel about 18.6 miles per second:

1115.876591933 ÷ 60 = 18.597943199

Google says the diameter of the Earth is 7,917.5 miles. So, as fast as the Earth is traveling, a catastrophic meteor has about a 7 minute window to hit target Earth.

7917.5 ÷ 18.597943199 = 425.719119329 seconds
425.719119329 ÷ 60 = 7.095318655 minutes

What are the odds of a catastrophic meteor hitting the Earth? Or, maybe a better question: What of the odds of the Catastrophic Earth hitting a poor meteor!?

abiogenesis - Good source that explains the evolution of single-celled organisms "from scratch"

From a more geology-oriented perspective:

Robert M Hazen (2007) - Genesis: The Scientific Quest for Life's Origins

Noam Lahav (1999)- Biogenesis: Theories of Life's Origin

J William Schopf (2001) - Cradle of Life

I have watched Hazen's nice "Origins of Life" DVD/Video Course. There he says that the Miller-Urey stuff has gotten less popular. Their atmosphere contains too much Nitrogen, Hydrogen and focuses on the water surface and the open water body.

More recent research points to a more CO₂-rich atmosphere, and that life evolved deeper in hot water at the bottom of the ocean.

Which organisms have the neuroanatomy Roger Penrose supposes play a role in consciousness?

Microtubules are a structure in the cytoskeleton, they are rope like polymers that grow to a length of about 25 micrometers (25000 nm), and have an outer-diameter of around 25 nm. For comparison, the mean spacing between atoms is on the order of 0.1 to 0.2 nm; so the micro tubule really is micro: about 200 atoms across. In terms of quantum effects though, this is pretty big but not unreasonable. Researchers commonly use quantum dots to play with quantum effects, and these are typically spheres on the order of 10 to 50 atoms in diameter. Note, that we don't know how to couple 5000 quantum dots in one coherent chain (how many you would need to get the length of a microtubule).

So microtubules are small, but they are common! Microtubules are found in all dividing eukaryotic cells and in most differentiated cell types. In other words, that mosquito you just smacked and that philosophers always give as an example of something non-conscious is full of microtubules. This should raise some red flags, but we don't need to go into more detail of microtubules to discredit Penrose and Hammeroff. However, if you love cell biology, take a look at Desai & Mitchison (1997).

So microtubules are probably a bad basis, but why did Penrose want quantum effects in the brain? In The Emperor's New Mind, Penrose suggests consciousness is non-algorithmic and suggests that a magical quantum computer could do these non-algorithmic tasks. The reason I use 'magical' is because a real quantum computer is Turing-complete, if a classical computer cannon solve a problem then neither can a quantum one (of course, if a classical computer can solve a problem, then quantum one can as well and might be able to do it qualitatively faster). For a nice computer science debunking of this part of Penrose's argument take a look a Scott Aaronson's lecture notes.

Why did Hammeroff want quantum-ness? To avoid dualism in explaining consciousness. However, he has gone so far down the reductionist rabbit-hole that he popped out on the other side. He arrived at the same 'magic' we feared in dualism except now he called it 'quantum mechanics'.

The biggest irony of this approach is that Penrose was inspired in many ways by Schrodinger's beautiful take on life. Although Schrödinger does bring in quantum mechanics (both as a useful reduction and as an analogy) he uses completely different parts of it (he uses the discritization of energy levels, and specially avoids issues of the uncertainty principle and superposition of states that made him famous). Schrödinger would completely disagree with Penrose and Hameroff::

[I]f we were organisms so sensitive that a single atom, or even a few atoms, could make a perceptible impression on our senses -- Heaves, what would life be like! To stress one point: an organism of that kind would most certainly not be capable of developing the kind of orderly thought which, after passing through a long sequence of earlier stages, ultimately results in forming, among many other ideas, the idea of an atom.

This response can be made precise through quantum decoherence (Tegmark, 2000) and there is little regard for the physical importance of quantum mechanics in the brain (Litt et al., 2006) although Hammeroff (2007) still defends it.

What are the azimuths of the planets' orbits?

As someone commented, you are actually short a term for fully defining the orbit. The "azimuth" as you describe is commonly defined as a "longitude of perihelion", and you're forgetting the orientation of the inclination, commonly defined as "longitude of the ascending node." (Both of these values are included in the first link in the previous posted answer)

For a more detailed look at the math which uses the defining values, JPL made a whitepaper which goes into the math, and also allows you to account for changes in the orbital terms. (Most of the math you're probably looking for is at the end of the document, beginning about section 8.10, on page 25)

ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf

histology - What histological stain can I use for beta-keratin?

I'm trying to find a histochemical stain for beta-keratin, the type found in Reptilia which is organized in beta-sheets. It's different than alpha-keratin which is found in mammalian skin, hair, nails, etc., and is formed of alpha-helices.

Simple searches have produced results specific to mammals and alpha-keratin. Are there any good stains for beta-keratin?

orbit - How to get from the earth to another planet/ the moon? What happens on the way?

Short answer is easy. Long answer, there's lots of maths involved, and I'm out of practice with my maths, but there's a few basic parts that your students should be able to follow. It's a little confusing, not too bad.

We can ignore the Earth's motion around the sun for the most part but not the Earth's escape velocity.

Start with Newton's cannonball thought experiment. That will get you into space, and that's an example of orbital velocity. With a fast enough launch, the cannonball enters into and stays in Earth's orbit.

2nd, explain the difference between escape velocity and orbital velocity. Escape velocity is greater than orbital velocity and the cannonball that orbits the earth hasn't really escaped the earth, it's still in the Earth's gravitational sphere of influence. You need escape velocity (or very close to it) to get to the moon, about 11.2 KM/s. You can get away with a bit less cause the Moon hasn't fully escaped the Earth either.

Astronauts can't get shot out of a cannon at high speeds cause it's too many G forces, so what rocket launches do is accelerate over a few minutes. (you could probably look up the precise amount of G forces), but within G forces that humans can tolerate. If they experience 4Gs, they're accelerating the equivalent of 3Gs (or 29.4 meters per second), at least at first, as they move away from the Earth, the gravitational acceleration towards the earth drops and after only a few minutes they can shut down the launch and drift towards the moon. Most of the trip to the moon is done in this way, just drifting through space. You don't want to go too fast cause you'd just need to slow down as you approach the moon again and the moon has no atmosphere to assist the deceleration like the Earth does.

The ships momentum traves through the combined gravitational field of, primarily, the Earth, Sun and Moon, and the Maths get pretty complicated, so the the launch needs to be quite precise.

The Moon also orbits the Earth at about 2,300 miles per hour and that orbital speed has to be matched as well as, since the rocket will often enter a partial orbit around the moon, that orbital velocity around the Earth needs to be matched too.

Once this is done, landing on the moon requires a simple enough deceleration to have a gentle enough touchdown to not harm any equipment. (this probably isn't as easy as it sounds).

An orbit around the moon isn't strictly necessary but a partial orbit was used to assist landing on the desired spot. A partial orbit around the Earth was also used in the launch to the moon.

They accelerate away from the Earth in 2 different times, first to leave the earth and get into Earth orbit. That's the big one, then from a different spot (and not even an hour later) to accelerate out of Earth's orbit towards the Moon.

See diagram.

Source

At least, that's a pretty basic summary. I welcome correction if I got anything wrong or missed anything important.

observation - How often and over what period is Earth’s rotation averaged to compute UT1?

Conceptually, the average is over an average year. Practically, that's not what's done anymore.

Sidereal time is much more readily measured than is solar time. Radio astronomy can measure the position of remote quasars much, much more precisely than they can measure the position of the Sun. The Sun is a big fiery blob with a not quite-well defined surface. Quasars are pinpoints. Very long baseline interferometry makes the observations of those quasars extremely precise.

The equation of the equinoxes converts between apparent and mean sidereal time. A very simple relation converts between mean sidereal and mean solar time. This makes variations in UT1 observable on a rapid basis. Sub-arc second astronomy depends on these rapid updates. IERS Bulletin A is updated daily, with the data for the most recent week or so subject to subsequent small updates.

Update

Universal Time is not based on apparent solar time. Time is now effectively divorced from the the apparent revolution of the Earth with respect to the Sun. It took several thousands of years to make this divorce final. (And the divorce is still not quite final. There's the matter of leap seconds. There's a proposal to eliminate leap seconds that has been shelved/postponed multiple times since 2003. A vote is scheduled for 2015.)

The ancient Egyptians divided daytime into 12 equal parts and nighttime into 12 equal parts. Daytime and nighttime hours were of different lengths, and these lengths varied over the course of a year. Hipparchus (190 – 120 BCE) suggested dividing one day into 24 equal parts, the basis for our modern hour. Ptolemy, using information already garnered by ancient Babylonians, asked "what day"? The length of a solar day (local noon to local noon) varies over the course of a year thanks to what we now call the equation of time.

This was of mostly academic interest until Christopher Huygens' development of the pendulum clock in 1656. Pendulum clocks tick at a rate proportional to the mean solar day rather than the apparent solar day. Those early pendulum clocks weren't particularly accurate. They had to be reset on a regular basis. The equation of time was central in determining the time to which those clocks needed to be set.

By the mid 1800s it was becoming apparent that even a mean solar day was not that good a basis for defining time. The clock kept by the solar system didn't agree with a clock kept by the Earth's mean rotation. A clock based on the solar system was more accurate and more consistent than was a clock based on the Earth's rotation.

By 1900, the divorce between Earth rotation and time was well on its way to being finalized. The basis for time was switched from the Earth's rotation to the clock kept by the solar system, with the second based on the length of a year rather than the length of a day. About 150 years of observations of the length of the mean solar day went into that circa 1900 definition of the second.

In 1967, time was further divorced from the clock kept by the solar system. By that time, atomic clocks had become extremely accurate devices, better than observations of the solar system. The International Atomic Time second was defined to be consistent with that circa 1900 definition of a second, which in turn was defined to be consistent with that ~150 years of observations of the length of an apparent solar day, centered on about 1821.

That 1821-based definition of a second as 1/86,400 of a day is no longer correct. A day is now about 86400.002 seconds long, and it will grow longer with passing millennia. This leads to the need to insert leap seconds to keep UTC in synchronization with the Earth's mean rotation. There is considerable debate with regard to whether even that should be done. There is a serious proposal to abandon leap seconds. This is now scheduled for a vote in the upcoming year (2015).

pharmacology - Resources for finding all drugs of a certain class

The WHO has their own methodology, the Anatomical Therapeutic Chemical (ATC, thank you commenter) classification system, for organizing such data (its impetus is comparing results between studies).

Also, if you have $900 sitting around, you can get a subscription for the United States Pharmacopeia. I'm not sure if that can be spread across multiple subscriptions for an organization like the Red Book David mentions.

Strength of gravity during the big bang?

The truth is we do not have a working or widely accepted "theory of everything" that unifies gravitation with the other fundamental, and quantum, field theories. What we do have is strong evidence that the other field theories - electromagnetic, strong nuclear and weak nuclear - are unified at high energies (indeed the evidence is so strong that I doubt it is widely disputed at all).

We do have a theory of gravitation - general relativity - that appears to work well in "most" circumstances, though it also has a singularity (black holes) and there is a fundamental difference between it and the quantum theories about vacuum energy (the so-called vacuum catastrophe).

What we also know is that gravitation appears to much weaker than the other forces, though it can act over very large distances and so is fundamental in shaping the nature of our universe.

There are various arguments about how/why our universe is able to support life/is the way it is. Perhaps it is just one of many/an infinite number of universes that have a range of physical properties and we just happen to be in one that "works" for life - obviously there could be no life in a universe that had physical properties that didn't support life.

At another extreme perhaps we are all inside a computer simulation.

I'd suggest hunting down works by Max Tegmark or Brian Greene for more information.

telescope - Why is the moon a fuzzy, white ball?

Your telescope is not focused (most likely), or is having some major collimation issues (less likely).

Try and move the eyepiece back and forth a little. Go through the whole range of the focuser. You must catch the primary focal plane in order for the image to become clear.

If that doesn't work, pull the eyepiece out a few mm and try to move through the whole range again.

If that doesn't work, try a different eyepiece.

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The "advice" regarding the Moon filter is bogus. Be careful regarding what you hear on the Internet. The eye is certainly capable of adapting to various levels of brightness. Even with very large telescopes, the Moon filter is useless. All it does is reduce the brightness and contrast - the former is no big deal, but the latter is a major loss. You can never have enough contrast in a telescope.

When the Moon is visible, there's no point in going through deep dark adaptation anyway, because the "faint fuzzies" are obscured by Moon's glare. When I watch the Moon, I do it from a fully illumined backyard, or even on the street under the street lights. In fact, this is the best way to observe this object - no filters, but have some ambient light around you. Your eyes will function at optimal parameters.

Deep dark adaptation is only needed when observing faint nebulae and galaxies. But such objects can be observed in good conditions only when the Moon is below horizon.

Let me make it clear: a filter, any filter, will not fix the problem you're having, because it does not address the root cause.

Beware of most cases when the advice you receive is "use a filter". In 99% of cases, it's bogus. Many people own filters, but only a very small fraction know how to use them. In the vast, vast majority of cases you don't need any filters. Please steer clear of this superstition. It's a fad that vendors are more than happy to feed, because it makes them money.

There are legitimate ways to use filters (in the rare cases when they're justified), but that would be the subject of a different discussion - those rare cases are related to certain techniques of increasing the apparent contrast in the image. A neutral density filter (a.k.a. "moon filter") always decreases apparent contrast.

In this hobby, like in most other hobbies, a lot of people fixate on purchasing all sorts of accessories (in this case: filters), hoping to get extra performance, when all they need to do in reality is learn how to use the device / machine / etc (in this case: telescope) correctly. I see this tendency in all my other hobbies. It's unfortunate, and a huge money sink.

Save the money and use it instead towards purchasing a better telescope, or better eyepieces, or a good sky atlas, or an observing chair, etc.