idleCycle

Hitchens & Fry obliterate the catholic bozos. Frankly, I think the organizers should have tried to get more eloquent and better prepared speakers in favor. That would have made the "debate" more interesting.

Delay-tolerant networking (DTN) is an approach to computer network architecture that seeks to address the technical issues in heterogeneous networks that may lack continuous network connectivity. Examples of such networks are those operating in mobile or extreme terrestrial environments, or planned networks in space.
Recently, the term disruption-tolerant networking has gained currency in the United States due to support from DARPA, who have funded many DTN projects. Disruption may occur because of the limits of wireless radio range, sparsity of mobile nodes, energy resources, attack, and noise.

DTN networks would also be very intersting here on earth. For example for users of mobile devices in regions where network coverage is bad e.g. when you're driving through a tunnel or go underground, etc. In fact some research groups have suggested these kinds of improvements for future Internet architectures. The original architecture was designed with stationary computers in mind. I guess it makes sense to accomodate these new types of devices in future networks.

To proponents, space elevators promise to slash the cost of sending cargo and people into space. And, they say, elevators would eliminate the costly need to overengineer satellites and other payloads to survive the rigors of a launch.

How does something buried inside an ice ball only 311 miles wide, provide the pop to propel a plume 600 miles out of the moon's south pole? "The biggest puzzle with Enceladus is where is the heat source," says Cassini scientist Linda Spilker of NASA's Jet Propulsion Laboratory, which manages the mission. "This tiny moon 'should' be frozen over like the others orbiting Saturn."

Galileo Galilei experimentally confirmed Nikolaus Copernicus' revolutionary theory of the heliocentric model that replaced the preceeding geocentric model, established by the greek astronomer & astrologer Claudius Ptolemaeus, that had prevailed for over a thousand years. Copernicus handwrote his 20 page pamphlet, the 'Commentariolus', in 1514. He constructed a sun-centered model of the universe in which all planets orbit around the sun. It already contained all the key insights:

- Heavenly bodies don't share a common center
- The Earth is not at the center of the universe
- The apparent daily motion of the stars is a result of the Earth's rotation
- All planets revolve around the sun
- The apparent retrograde motion of the planets can be explained the revolution of the Earth around the sun

What's more, this new copernican model was much simpler than Ptolemaeus' model. Copernicus then spent another 30 years(!) to expand his work to a complete 200 page manifest based on his original pamphlet. His work De revolutionibus orbium coelestium (On the Revolution of the Heavenly Spheres) was finally published in the spring of 1543. Anectode has it that he received a printed copy of his book on his death bed.

However, one of the biggest shortcomings of Copernicus' model was that it was less accurate than the much more complex Ptolemaic model of the epicycles. Those shortcoming were later addressed by Johannes Kepler who realized that Copernicus had been wrong about some points. He showed that:

- The planets move in ellipses not perfect circles
- Because of that the speeds of the planets vary
- The sun is not quite the center

To give Credit where Credit is due, Keplers theories were also based on observational data collected by the Danish astronomer Tycho Brahe. With Kepler's refinements, the new model was more accurate than the old one. His breakthrough was published in 1609 called the Astronomica Nova after eight years of work. The same year Galileo Galilei experimentally confirmed these theories. He showed that the Earth is not at the center of everything, because Jupiter has its own satellites. Also, he showed that the phases of Venus are only compatible with a sun-centered universe.

That's the history lesson for today. So the next time you read or hear about Galileo, also remember those great theorists and experimentalists, namely Copernicus, Brahe & Kepler who came before him.

φshing for domain names, i.e. registering legit looking, well-known URLs for malicious websites is the next bad thing.

They're on a mission from God

Shamelessly lifted from the Abstract:
Multicore computers are here: is your programming language ready for it? Haskell is: you can take an off-the-shelf copy of GHC and write high performance parallel programs right now.

If you want to program a parallel machine, a purely functional language such as Haskell is a good choice: purity ensures the language is by-default safe for parallel execution, (whilst traditional imperative languages are by-default unsafe). This foundation has enabled Haskell to become something of a melting pot for high level approaches to concurrent and parallel programming, all available with an industrial strength compiler and language toolchain, available now for mainstream multicore programming.


The talk outlines the various ways to get concurrency and parallelism in Haskell. More information can be found on the Haskellwiki page.

There is also a whole chapter in Real World Haskell devoted to 'Concurrent and Parallel Programming' featuring explicit threads using forkIO, synchronized shared variables in form of MVars. Moreover, there's examples of implicit parallelism - called sparks - showing the application of par and pseq combinators.

Oh btw, there's also a complete chapter about Software Transactional Memory. This is really intriguing. The approaches above relied on explicit locking of shared variables. MVars behave similar to mutexes and semaphores in procedural programming. And they suffer from the exact same problems: deadlocks, race conditions, uncaught exception etc. STM provides a way perform database-like (i.e. ACID) transactions on shared variables including retries and rollbacks. You never have to worry about your shared data again. STM is not unique to Haskell, but it hasn't caught on in the mainstream yet.

These two chapters cover pretty much anything mentioned in the slides. Not suprisingly since Don Stewart, who held the talk, is one of the coauthors of Real World Haskell.