4,520 reputation
11521
bio website vyznev.net
location Helsinki, Finland
age
visits member for 3 years, 1 month
seen 8 hours ago

I'm a PhD student in biomathematics, working on stochastic individual-based models of evolution in spatially structured populations. My other interests include cryptography, programming games and puzzles, photography and graphic design.

I started programming (in AmigaBASIC) when I was 10 years old. Nowadays, I'm most comfortable using Perl, C and JavaScript. I know Java and PHP too, but I can't really say I like them. I also know some Python, but not as much as I'd like.


CC-Zero Please consider any (original) code I post to Stack Overflow and other Stack Exchange sites to be released under CC-Zero unless stated otherwise. You may do whatever you want with it and don't have to credit me in any way, although of course that would be nice.


I'm the main author and maintainer of the Stack Overflow Unofficial Patch (SOUP), a user script for browsers with GreaseMonkey-compatible user script support (Firefox, Chrome, Opera, possibly Safari) that fixes or works around a number of outstanding issues with the Stack Exchange user interface.

I tend to answer a lot more questions than I ask. Some answers I'm rather proud of:


Jan
28
awarded  Custodian
Jan
28
reviewed Approve suggested edit on Can I excite an already unstable element for accelerated decay?
Jan
25
revised Why do chimneys have these spiral “wings”?
use protocol-relative links to avoid mixed content warnings when using https
Jan
19
comment Very strange shadow phenomenon
I don't think this is the full answer. The thing is, convolution (including blurring) and multiplication don't commute, so you'll get different results if you merge the layers before you blur them (which is closer to the real situation, assuming the book and elbow are at approximately the same distance from the wall). And indeed, doing it "correctly" should generally make the "bridge" region between the shapes darker than in your example.
Jan
18
answered Why does tossing a coin in a train and on a train differ?
Dec
16
answered How to measure resistance of a piece of wire?
Dec
16
awarded  Civic Duty
Dec
16
comment How to measure resistance of a piece of wire?
@BrandonEnright: So use insulated wire?
Dec
1
comment Rotation of a slipping ladder
@ja72: Perhaps we're coming from different viewpoints here. I agree that the DoF reduction trick is neat here (and gave you a +1 for it), but coming from a numerics background, for general use I'd rather prefer a representation of motion that a) did not change in the absence of external forces, b) worked for all rotation rates, including zero, and c) was easy to (approximately) integrate over time. Translation + rotation around the CoM fits those criteria.
Dec
1
comment Rotation of a slipping ladder
@ja72: Only if you insist on describing the (instantaneous) motion as a pure rotation, rather than as a rotation plus a translation. Admittedly, that's what the OP seems to be asking for (since otherwise their question doesn't make much sense), but in general it doesn't seem to me like a very useful way to model rigid body dynamics.
Nov
29
comment Is there a way for an astronaut to rotate?
@EmilioPisanty: Yeah, but it's about as close an approximation as you can get without actually going into space. In practice, those chairs tend to have pretty low friction (at least if well maintained), so unless you do the exercise at a snail's pace, it can be mostly neglected. (As a double check, you can try holding the object at a constant distance, but moving it left and right at different speeds. If you don't observe any significant net rotation, that means the effect of friction was negligible.)
Oct
22
awarded  Nice Answer
Oct
12
answered Why in Newton's law of gravity, we do $M_1 \times M_2$ and not $M_1 + M_2$?
Sep
16
comment What is vacuum to DC flow?
Does a vacuum tube still count as "common circuitry"? Because, you know...
Sep
13
comment What is the difference between the Balmer series of hydrogen and deuterium?
A minor nitpick on an otherwise excellent answer: while high concentrations of heavy water do indeed inhibit eukaryotic cell division, at least some bacteria and other prokaryotes will grow just fine even in 100% heavy water. That's how perdeuterated biochemicals are produced.
Sep
11
awarded  Good Answer
Sep
9
awarded  Nice Answer
Sep
9
answered Are the air particles in today's wind on earth (more or less) the same as the air 2/3 billion years ago?
Sep
3
awarded  Nice Answer
Sep
2
comment Why does blowing on a candle put it out but sucking doesn't?
Also related: What happens, if a rocket is filled with a vacuum instead of high pressured air?