Tuesday, August 25, 2009
Monday, August 24, 2009
I needed to convert a bunch of files saved in a few Unicode encodings and I found the Unicode table for you, Unicode HOWTO (for Python), and Ascii Table MS-DOS Codepage 874 (Thai) pages very useful. I'm writing this down in case someone needs to do similar things for Thai files.
Saturday, August 22, 2009
Smart Wiki Search is a nifty tool that can show you related concepts in Wikipedia when you enter one or more concepts in the search box.
Sunday, August 16, 2009
I found this paper (When Zombies Attack!: Mathematical Modelling of an Outbreak of Zombie Infection) very funny and informative. It's a real mathematical modelling of how a zombie outbreak might occur by viewing it through infectious disease models.
The main points:
An outbreak of zombies infecting humans is likely to be disastrous, unless extremely aggressive tactics are employed against the undead. While aggressive quarantine may eradicate the infection, this is unlikely to happen in practice. A cure would only result in some humans surviving the outbreak, although they will still coexist with zombies. Only sufﬁciently frequent attacks, with increasing force, will result in eradication, assuming the available resources can be mustered in time.
In summary, a zombie outbreak is likely to lead to the collapse of civilisation, unless it is dealt with quickly. While aggressive quarantine may contain the epidemic, or a cure may lead to coexistence of humans and zombies, the most effective way to contain the rise of the undead is to hit hard and hit often. As seen in the movies, it is imperative that zombies are dealt with quickly, or else we are all in a great deal of trouble.
Saturday, August 15, 2009
Novikov Self-Consistency Principle: Why You (Most Likely) Cannot Use A Time Machine To Change The Past
If we have a time machine, is it possible to go back into the past and change it?
That's a question many people have thought about. It turns out that if there's no parallel universes, the Novikov self-consistency principle should hold and that there is no way to change the past. What has happened cannot be undone. Whatever actions from the future are already accounted for in what has happened.
So, the movie The Terminator agrees with this principle: The terminator going back in time created a consistent loop that would create John Connor who would then get into a situation where a terminator must be sent back in time, and in the process would create John Connor, and so on. However the Terminator 2, 3, and 4 movies deal with changing the past/history, so they are less realistic according to this principle.
Saturday, August 08, 2009
Although human have been directing evolution in other organisms for thousands of years (such as breeding dogs, fruits without seeds, high-yield rice, etc.,) I'm still very impressed to hear that researchers are evolving bacteria to produce more electricity in fuel cells.
Here is the excerpt (MFC = Microbial Fuel Cell = a kind of fuel cell to generate electricity):
"In order to produce electricity, it is imperative that MFC's bacteria conduct electrons to the cathode. The researchers at UMass Amherst realized that there has never been any natural selective pressure that would enhance electronic conduction in bacteria, so they used directed evolution to produce highly conducting bacteria.
G. sulfurreducens bacteria were cultured on a graphite electrode under a 400 mV applied bias. The goal was to force the bacteria to adapt to conditions inside the MFC with the hope that they would evolve greater functionality in the process. Several colonies were isolated after five months in the MFC environment and re-cultured under normal conditions. When placed in an MFC cell, the specially cultured bacteria grew much more rapidly—current saturated after 50 hours as opposed to 400 hours—and they provided twice the current density of normally cultured bacteria."
Friday, August 07, 2009
Sunday, August 02, 2009
"Scientists are pieces of the Universe trying to understand itself." --Anonymous.
If you have ever been a student in my class or if you are curious how scientists learn how Nature actually behaves (as opposed to what we presume Nature should behave), I highly recommend you read the following essay: Strong Inference.
It was written about 5 years before I was born, but I've just been aware of it. The message is as true 45 years ago (actually, as true as at least 400 years ago when Galileo started modern science) as it is today.
From what I know about biology, I'm pretty sure that we are descendants of a unicellular organism that ate ancestors of mitochondria. Our ancestors got to use super high power generated by mitochondria's oxygen-base metabolism, so they could move better, hunt better, evade predators better, and in time mutated into us and all living things that have mitochondria in their cells. (By the way, all mitochondria in you come from your mother; your father's sperm was too small to carry any mitochondrion. When my kids misbehave, I would turn to my wife and tell her "Titus/Tatia/Tanya got your mitochondria.")
I just read an interesting account of something analogous to what our unicellular ancestors might have done: a carnivorous cell hunts other things until it eats a particular type of unicellular plants; it then turns into a photosynthesizing organism and stops hunting. When it reproduces (by binary fission), one offspring becomes a hunter, the other becomes a plant.
Two researchers have shown a striking example of endosymbiosis forming now: in 2005 Noriko Okamoto an Isao Inouye reported on a unicellular organism called Hatena. Hatena (”enigma” in Japanese) leads a curious life cycle. Hatena is a single-cell organism, swimming around in the water, using a little feeding apparatus to eat cells and organic material smaller than itself. At some point, it would feed on another unicellular algae, the Nephroselmis. Once Hatena swallows Nephroselmis, it does not digest it. Rather, Nephrosolmis makes itself comfortable home inside Hatena. The alga starts growing inside Hatena: it grows to about 10 times its original size, filling up most of Hatena. The alga also seems to lose most of its own organelles, except for the chloroplast. The chloroplast actually grows bigger.
Hatena changes too as a result. Before ingesting the alga, it has a rather complex “mouth”, or feeding apparatus. After ingesting the algae, this mouth disappears only to be replaced by an eyespot from the algae. The eyespot is a light sensing organelle, a very primitive eye, that guides algae to light sources. In this case, it also guides the host, Hatena, to light. Hatena has obviously stopped feeding, and least through its mouth. It is now swimming to the light, letting the alga photosynthesize its food for both of them.