Gender Achievement Gaps in Science and Maths

I read this paper from Science, Nov. 2010, about how female college students who are Physics majors can benefit by what the authors term ‘Values Affirmation’. They make the participants write brief essays about ‘values’ that the students consider important to themselves, once at the beginning of the (15 week long) semester and once at the end of the semester five weeks.

The underlying assumption in the study is, of course, that there is no ‘reason’ that female students have to perform any poorer because they happen to be female. The authors argue that female students feel the burden of their stereotype – an effect also seen in black students, for example: black students feel their performance will be used to judge their community. If putting the female students at ease is possible, therefore, one would expect that this will help their grades.

The authors say the study is randomised and double-blind. Neither the teacher nor the teaching assistants knew which students got either the ‘actual medicine’ or the control, which was to write about values important to somebody else. I don’t know if this is important or even enforceable. (The students were told the essays were part of the course evaluation, as far as I can tell. How do you stop people from talking about the exam they just wrote outside class?)

In any case, the results of the study seem impressive. Female students who were asked to write about values that were important to them did better in the course, and got better scores on a standardised test of conceptual physics. (Incidentally, men who were asked to write about values that were important to them did worse than the control group. Go figure.)

The study has gone to extraordinary trouble in some aspects. The TAs administering tests to students were given scripted answers to possible questions that students might ask, for example. A la at your friendly neighbourhood call-centre. I do have some cribs with the study, though.

I’ve already mentioned my first crib about whether the study is truly double-blind. Second, and this might seem like a stretch, the essays were given as part of the course – the students were told that effective communication was important in science. I don’t think it’s unthinkable that writing about something that’s important to you is easier than writing about why something that isn’t important to you might be important to somebody else. Is it possible that people who were asked, twice, to write about somebody else got freaked out that they’d (predictably) done the essays badly and did worse in the actual course because of this?

Another possible question that may be asked is that if all it takes to get female students to do better is to have them talk about their values, this should already have happened when colleges implemented other programmes to help female students. The authors say, for example, that special attention was paid to female students and it didn’t seem to do too much.

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Miyake A, Kost-Smith LE, Finkelstein ND, Pollock SJ, Cohen GL, & Ito TA (2010). Reducing the gender achievement gap in college science: a classroom study of values affirmation. Science (New York, N.Y.), 330 (6008), 1234-7 PMID: 21109670

Monday. More interesting stuff

This seems to be an easy thing for me to do, putting up these links to articles and stuff that are interesting and worth a look. I’m going to be doing this frequently till my D-day is past. Anyway, on to the stuff:

1) This past week saw truly groundbreaking achievements in Physics. One of them was the first Bose-Einstein Condensate of photons. I will readily confess that I know nothing of these things beyond the name. But as far as I could make out, photon BECs were either thought impossible, or were never actually synthesised until now. You might note that the people who first created a BEC won a Nobel for their work. The paper is available from arXiv.

The other is perhaps conjectural (I know less of this than the previous thing, if that’s at all possible) and is Roger Penrose’s work with cosmic background radiation and a theory that aims to explain what happened ‘before’ the Big-Bang. ‘Before’ the Big-Bang, you ask? Yes. Apparently, some parts of the cosmic background radiation is consistent with being from before the current ‘aeon’. And Penrose claims that this theory should replace Inflation. The paper is available from arXiv.

2) Srinivas points out that if you have some spare time, you might consider transcribing the 106 tapes of audio that seem to have taken the Indian media world by such storm. Did Barkha Dutt or Vir Sanghvi act as lobbyists for some political party? Well, go listen. (And type.)

3) Do you like radio? Are you also perhaps an open-source fan? Well, here’s Linux Radio, a site that reads out the Linux operating system’s kernel, one random file at a time! Asterisks and slashes and <includes> included! [Hat tip: Slashdot]

4) And finally, like always, we end with some intelligent comics; it turns out both have something to do with incredulity.

First, Abstruse Goose and the tendency science reporters have to misreport stories:

[carroll]

[/carroll]

And finally, Jesus and Mo, on the selective skepticism (perhaps ‘hypocrisy’ is a sharper word to use) of organised religion:

[/jesusandmo]

Pencil and paper

I draw. Somewhat. And only once in a while. But most of what I ‘draw’ has so far been on MS Paint. This one isn’t. I actually drew this on paper, with (an HB) pencil. I spent all of twenty minutes on it. (Putting this post up has taken longer than it took to draw.) Predictably, it isn’t very good. On the other hand, where else will I get to foist my ‘art’ on the world?

Make of it what you will.

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Normal programming, as I’ve said, will probably only resume after December 7.

It’s Saturday. There has to be something good.

I lamented once upon a post that I seemed to leave my camera behind really when I might have liked to take a picture. Well, that’s been remedied. Partially. Here, for instance, is quite a large cloud of birds.

[birds]

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I’ve seen birds in bunches smaller than this do simulated acrobatics, too. They fly around in circles gaining altitude and hurtle down all together in swoops that will make you think they’ve suddenly lost the ability to fly… until you see them resurface from behind the trees in a few seconds. I wish I knew how to get that on camera.

Here’s another one. You know what they say about clouds – that each one has a silver lining? I don’t think they meant that literally, but here’s what that might look like:

[silver]

[/silver

And lastly, and I am not sure that the resolution on this page is enough to see this properly, does it look to you like the branches of the coconut tree are on fire, the flames eating at the leaves from tip to stalk?

[fire]

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Random pictures, Random games

I am going to be busy for the next two weeks or so with topics decidedly fluid-mechanical. Here at the blog, then, there will be little original material while I get my flu-mech hat on and try and get through a PhD admission interview. Here are some things that should keep you occupied, at least until tomorrow:

First, a brilliant idea implemented well. A tone-matrix that lets you create your own beats, designed by somebody called Andre Michelle. Good one, Sir!

Second, you know how Sheldon Cooper is fond of text-based games that run on the most powerful graphics processing utility yet created (imagination)? Here’s a site that let’s you play some classic text-based games, using an emulator that runs on Java.

Third, a timelapse video of the Aurora Borealis from APoD. The Sun’s just come out of a prolonged activity-minimum, and is expected to increase in activity over the next three years or so. Auroras can be seen more frequently.

Lastly, and I won’t fault you too much if you think this is beating a dead horse, but Sarah Palin’s gone ahead and… well, see for yourself.

Back-of-envelope physics

If you remember debates about education from high school, the most common complaint you would’ve heard is that education today has too much memorisation. In fact, that refrain isn’t just used in high school; it’s the knee-jerk reaction of any educated person who is asked to name something that’s wrong about the education system.

The best teachers (of physics, and other things) I know think otherwise. The thing is, people are forced to memorise things without knowing why they need to remember those equations or numbers or what have you. Here’s a (somewhat arbitrary) for-instance: what’s the ‘ideal set’ of BWH measurements for a woman? I think I can safely say that anybody who remembers the numbers (36-24-36) doesn’t feel awfully burdened by this tax on their memory. Memorisation isn’t hard when you know where you’re going to use what you’ve memorised.

I thought I’d write down a few examples of where remembering numbers or equations can tell you interesting things. First, a simple example that requires nothing more than high-school physics:

I’ve written at length about how IISc’s roads are tree-lined and how this makes any pedestrian a prime target for bird-poop. I was walking to my room from the bus stop the other night, when the birds were especially, erm, active, and saw somebody walking in front of me. Suppose I saw a glob of poop as it left the bird, and wanted to warn the person in front, would I be able to – even assuming ideal circumstances – help them escape?

If the trees are about five human-beings tall, and you remember high-school kinematics, you can calculate (go ahead, do it!) that you have a little more than a second from launch to hit. You should also remember that reaction times for human beings are of the order of half a second. This is assuming that the person you randomly yell at on the road understands exactly what you’re saying and moves in exactly the right way. Seems implausible, doesn’t it? Probably is!

Here’s a somewhat more involved one that might seem arcane: Say you wanted to find out how fast molecules vibrate. To make things specific, say you wanted the time scale of vibration of a H2 molecule. (I say H2 to be on the safe side – Hydrogen’s vibrational mode becomes fully excited at about 4 K.)

What you will need to remember is the equipartition theorem of (statistical) thermodynamics: each degree of freedom adds 1*kT of energy to the molecule. You also have to remember, from quantum mechanics and the harmonic oscillator, that energy is Plank’s constant times the frequency. At room temperature, the H2 molecule has a vibration frequency of about one petaHertz. (Continuing along these lines, can you think of how you would estimate the speed with which atoms in the molecule move in course of these vibrations?)

Here’s a third one: suppose you want to find out how much iron you could quench with a given quantity of water. To make things specific again, say you had water at room temperature, and you’ve just heated iron to red-hot. How much water would you need to quench a bar of iron that weighs about 1 kg? Equivalently, what weight of iron can you quench with a bucket of water? Let’s say I give you that the temperature of the water cannot rise by more than one degree.

You’ll need to know that a normal bucket holds about twenty litres of water. You’d also need to remember that the specific heat of water is about 1 calorie per gram per degree Celsius. There is a law in physics called the Dulong-Petit law (equivalent to the equiparitition theorem) that says that the specific heat for solids is 3R, or about 6 calories per mole per deg Celsius. 1 kg of iron is (you’d have to remember that Fe has an atomic weight of 54) about 20 moles. Also, iron becomes red-hot at a temperature of about 300 deg C. This should tell you, with some mental arithmetic that you’d need about two buckets of water to quench a kilogram of red-hot iron.

In the three examples, there are about a dozen numbers or properties that one would’ve had to remember to do the calculations. My point is that this tax on your memory isn’t necessarily cumbersome. Memorisation is only ‘rote’ if you make it so.

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I must confess that I had to look up Fe’s atomic weight. As penance, here’s yesterday’s Abstruse Goose webcomic about relativity. Do you get it? (How close to the speed of light is the Flash running? The answer’s 0.99… to quite a few 9s)

[Einstein!]

[End. Fini. Kaputski. Einstein!]

Feminism and the burqa.

I read this essay in Tehelka’s true experiences section over the weekend. The essay is by a feminist who considers herself too ‘orthodox’ in her feminism. The essay is the story of how the author runs into, in a feminism-studies class at Delhi University, a female clad in a head-to-toe mobile tent; and the story of how this woman has made feminism her own, and created her own version of feminism. The essay concludes with a jibe at ‘orthodox western feminism’ (whatever that may be).

The author, who says she became a ‘voluntary critic’ [as opposed to Tourette’s?] of the burqa-clad woman at first, says she came to realise her folly after this masterpiece of reasoning from the latter (I’ve numbered what are put forth as arguments):

[1] “Well, this is my choice in a way. My choice even when I don’t have any other choices.” […] [2] “Why do you always set western feminism as a standard against which every other woman’s feminism is measured? Why a set definition? [3] Isn’t it tiring to put yourself on display all the time? Here, beneath this, there is a sense of serenity, a way which lets me feel free. This shield doesn’t let a stray man scrutinise me as an object. In yours words, that ‘commodifying western gaze’. This is not to say this is the ideal kind of feminism, but this is my kind of feminism. [4] Being a creature of a particular historical context, I don’t want to become so radical that my life is at stake. Isn’t that a choice again? What use is there for uninhibited radicalism if the fanatics of my community almost kill me? Isn’t it great that I’m studying a feminism course and have a friend like you?”

(4) is, by itself, a valid argument. There is no dishonour in saying ‘I find this treatment reprehensible, but if the alternative is death, I’ll go through with it.’ This, however, is about the only bit of sense in the apology for the burqa.

(2) is just plain silly. An expectation of the right of a woman to wear whatever the hell she wants is not the definition of ‘western’ feminism. It’s the definition of basic human decency.

(3) This woman’s definition of feminism includes the stereotyping of all men as pigs, and use of this as a rationale for wearing a tent to school, I guess. Why does everybody’s feminism have to be the same? Indeed.

(1) Making peace with something isn’t the same as making a choice. It is, in fact, quite the definition of not having a choice. Which the speaker says is what has happened with her. Which is known to have happened to others.*

I can think of two alternatives at this point: one, that this woman has indeed been threatened with repercussions if she doesn’t wear a burqa; I fail to see how this situation can be of ‘her choice’. Option two, rather ungenerously, is that this isn’t what has happened with this woman, and that wearing this symbol of oppression in public is a choice this woman has made. Which is her right, in a free society.

That she should choose to exercise her right to wear what she wants by wearing something that symbolises the oppression of half a billion women in the Islamic world is quite disheartening.

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* The story of the woman who was threatened for not wearing a veil is representative of a new trend in Kerala’s society and politics.

Pictures from NatGeo, Life below the ocean, traffic jams in the brain, and a few other things

Because I have nothing original to write, and am in fact preparing for a test on the morrow, here’s a bunch of stuff from ’round the interwebs that I thought was interesting:

1) A brilliant collection of pictures vying for a prize at National Geographic’s Photography Contest 2010. Look in particular for pictures of a supercell thunderstorm (2), the lightning strike at NY harbour (16) and the silhouette of the child (18).

2) Scientists have found life in the deepest layers of the Earth’s crust (called the gabbroic layer). These microbes live off hydrocarbons, apparently. Because the paper is in PLoS, you can read the entire paper without having to go through a paywall.

3) The bottleneck in the brain, from Carl Zimmer. A fascinating discussion of refractory periods where brain activity slows down. Read in particular about the experiments conducted (this appears on page 2) and how we only start timing our thoughts after the refractory period is over. [Hat Tip: Slashdot]

4) You can now add coffee stains to your LaTeX files, without a mug, or any coffee. Very nice! [Hat Tip: Some forty-something professors.]

And, since no list of links is complete without comics, here are two:

5) Jesus and Mo, talking about how Dawkins is worth more points than Grayling:

.

[/jesusandmo]

6) The Dilbert Strip of Nov 20, 2010:

[End. Fini. Kaputski. Links]

Do we learn to see?

The Nobel-prize winning neuroscientist Torsten Wiesel delivered one of IISc’s centenary lectures this past Monday. The lecture was about the visual system, and the very broad question of the importance of nature versus nurture. Prof. Wiesel started with a general introduction to several notable features of the visual system:  the columnar organisation of the visual cortex, binocular interactions, and orientation-selectivity in cells.

The cells in the retina are like pixels in a camera, except they have a centre-surround sensitivity: a bright spot at the centre is excitatory, so is a dark circle along the outer edge. The contrast between the centre and the surround is what matters, since these cells eventually add up the various potentials and pass the signal along if the net potential crosses a certain level.

Put a bunch of these cells in a line and you have a basic apparatus for orientation selectivity. Only when all three cells fire will you have a ‘line’, for example, because the cut-off potentials in the visual system are designed to be high. Here’s a caricature. In the figure, a line like ‘A’ will light up all three cells and therefore produce a spike in the resultant potential; a line like ‘B’, however, will excite only one of the cells and will not clear the threshold potential.

There are, of course, problems with this model. One that is immediately obvious is how the number of cells required scales with the five levels of the visual cortex. This, it turns out, is still an open problem.

In trying to address the nature-nurture question, Prof. Wiesel noted that in spite of the visual cortex being organised in five levels, all of which have the structure of self-organising maps (SOMs), it is still found that visual deprivation in infancy can lead to permanent visual impairment. He described experiments in which one eyelid of a newborn monkey was sutured shut.

It turns out that the eye that isn’t shut takes over almost all of the visual cortex and, left this way, remains dominant for life meaning that the other eye cannot ‘see’. It is also interesting that if the blinds are reversed – the sutured eye is opened and the eye that was allowed to see is sutured – the dominance in the visual cortex also reverses. The brain, as is well known, is quite plastic in early life.

This, however, only happens within a critical period from birth – about ten weeks. If therefore, the animal does not ‘learn to see’ in the first ten weeks after birth, it remains visually impaired.

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There is a paper from 1977 titled ‘Forest before trees’ in the J. Cognitive Psychology by B. Navon. It talks about how it is impossible to miss the global picture and look only at the details. A review of that paper is up next.

[End. Fini. Kaputski. Wiesel!]

Fractals in clouds – why clouds appear ‘cloudlike’

Clouds have distinctive shapes. Or they seem to have distinctive shapes. It turns out that is likely due to the fractal nature of clouds. Fractals, as pretty much anybody these days knows, are geometrical entities that have no intrinsic length scale. They are self-similar – that is, they repeat themselves at any scale you pick. Here’s a very nice picture of something that looks fractal.

The theory of fractals is surprisingly recent. Mandelbrot published his seminal work on fractals only in 1977. Since that, though, people have found and used the theory of fractals in a number of fields. Protein folding, for example, shows fractal behaviour (to be correct, proteins show this behaviour only in a section between the largest and the smallest scales). Turbulence has been shown to show fractal behaviour (although this is still an open problem).

The fractal nature of clouds was first shown in this paper in Science, from 1982. The basic characteristic of a fractal is its fractal dimension. Among the simpler definitions, or ways of calculating, the fractal dimension is the box dimension.

The idea is straightforward: for any ‘regular’ two-dimensional figure (the theory can be extended to more dimensions, but let’s not, for the purposes of this post), the area is related to the square of the characteristic length scale (the perimeter is a good substitute for this) of the figure. Equivalently, the perimeter is proportional to the square-root of the area. In fractals, however, the perimeter is related to the square-root of the area raised to the fractal dimension, D:

P ~ √(A^D)

The way one calculates the box-dimension is to lay out a grid over the figure of interest and count the number of boxes needed to cover the figure as a function of the grid-size. Then you find the perimeter of the boundary of the boxes you’ve included as part of your figure, and plug the area and the perimeter into the relationship above.

The study measures the box-dimension for cloud and rain areas at a wide range of length scales. Satellite pictures of clouds, with a maximum resolution of 4.8 km by 4.8 km are used. To go below this scale, radar ‘shots’ of rain-areas are used (rain-areas because radar scatters off rain particles) – these can give a minimum area of about 1 km by 1 km. The largest cloud the study spots is one with an extent of about 3000 km, with an area of about 1.2 million km.

There is a very nice physical argument to be made here: if clouds were of some fixed length scale, L, one could in principle consider the cloud area to be made up of large-scale structures (length > L) with small-scale noise superimposed (length < L). In which case, when the box-dimension is calculated, the answers for the large and small scales would be different. If, on the other hand, the box-dimension does not depend on the length scale, this would be equivalent to saying that the cloud has no inherent length scale.

It must be noted that it is a property of fractals that their lengths keep on increasing as the resolution is increased (the length scale of measurement is made finer). And because satellite and radar images have different maximum resolutions, the data obtained from the two have to be made commensurate. After this is done, the study finds that in the entire range of length scales corresponding to areas between 1 sq.km and 1.2 million sq. km, there is no change in the box dimension, which turns out to be 1.35.

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LOVEJOY, S. (1982). Area-Perimeter Relation for Rain and Cloud Areas Science, 216 (4542), 185-187 DOI: 10.1126/science.216.4542.185