Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Submission + - Entangled Histories: Climate Science and Nuclear Weapons Research (sagepub.com)

__aaqpaq9254 writes: Paul N. Edwards has a great paper about the links between nuclear weapons testing and climate science. From the abstract: "Tracing radioactive carbon as it cycles through the atmosphere, the oceans, and the biosphere has been crucial to understanding anthropogenic climate change. The earliest global climate models relied on numerical methods very similar to those developed by nuclear weapons designers for solving the fluid dynamics equations needed to analyze shock waves produced in nuclear explosions. The climatic consequences of nuclear war also represent a major historical intersection between climate science and nuclear affairs. Without the work done by nuclear weapons designers and testers, scientists would know much less than they now do about the atmosphere. In particular, this research has contributed enormously to knowledge about both carbon dioxide, which raises Earth’s temperature, and aerosols, which lower it." Great free paper at the Bulletin.
Hardware Hacking

Grad Student Invents Cheap Laser Cutter 137

An anonymous reader writes "Peter Jansen, a PhD student and member of the RepRap community, has constructed a working prototype of an inexpensive table-top laser cutter built out of old CD/DVD drives as an offshoot of his efforts to design an under $200 open-source Selective Laser Sintering (SLS) 3D printer. Where traditional laser cutters use powerful, fixed-focus beams, this new technique dynamically adjusts the focal point of the laser using a reciprocating motion similar to a reciprocating saw, allowing a far less powerful and inexpensive laser diode to be used. The technique is currently limited to cutting black materials to a depth of only a few millimeters, but should still be useful and enabling for Makers and other crafters. The end-goal is to create a hybrid inexpensive 3D printer that can be easily reconfigured for 2D laser cutting, providing powerful making tools to the desktop."
Operating Systems

Submission + - Linux Laptops Bestsellers in Germany (linuxtech.net)

An anonymous reader writes: "Two Linux Laptops in the Amazon.de Bestsellers top ten, both outselling Apple, is this another temporary fad, or is this a sign that no matter what Microsoft does, they can't keep Linux from conquering more and more of their OS market share?"

Submission + - Yamaha Files Patent for Electric Bike (goodcleantech.com)

adeelarshad82 writes: Yamaha has filed a series of patent applications for a production version of its 2005 Gen-Ryu hybrid concept bike. The new electric bike will employ the company's YZF-R6 600cc engine to power a generator, which in turn will drive the bike's rear wheel. Every Yamaha styling patent published over the last 20 years has resulted in a full production model, so there's no reason to believe this one won't make it either.

Submission + - Extra dimensions? Only if smaller than 3*10^-6 m!

Vincenzo Romano writes: The website of the fortnightly scientific magazine Science News is reporting today an interesting article about the maximum size of any extra dimension, if any.
A team of theoretical physicists and astronomers has calculated that any hidden extra dimension beyond our familiar three-dimensional space, a world known in physics parlance as a 3-brane, must be less than 3 micrometers.
The study has been submitted online by Oleg Gnedin, Assistant Professor of Astronomy at the College of Literature, Science, and the Arts of the Univesrity of Michigan and is based on observations on one of the oldest black holes ever found in our universe, lurking deep inside the NGC 4472 galaxy.
Basically, that black hole has not evaporated yet by the Hawking radiation on the predicted "short" short timescale, thus posing an upper limit to the size of any extra dimensions to less thab 0.003 mm.
So what? String theorists must buy better magnifying lenses if they want to prove to be right.

Slashdot Top Deals

A mathematician is a device for turning coffee into theorems. -- P. Erdos