On April 14, 2008, we issued our report on the Federal Aviation Administration’s (FAA) air traffic control modernization efforts. At the request of the House Committee on Transportation and Infrastructure, we examined three objectives: (1) trends in recent FAA capital spending, (2) changes in cost and schedule baselines of major acquisitions, and (3) the effect of the transition to the Next Generation Air Transportation System (NextGen) on existing projects.

Air Traffic Control Modernization

This report describes virtual reality technology, which uses three-dimensional user-generated content, and its use by the U.S. military and intelligence community for training and other purposes. Both the military and private sector use this new technology, but terrorist groups may also be using it to train more realistically for future attacks, while still avoiding detection on the Internet. The issues for Congress to consider may include the cost-benefit implications of this technology, whether sufficient resources are available for the communications infrastructure needed to support expanded use of virtual reality technology, and whether there might be national security considerations if the United States falls behind other nations in developing or adopting this new technology. This report will be updated as events warrant.

Avatars, Virtual Reality Technology, and the U.S. Military: Emerging Policy Issues

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The Bloom filter, conceived by Burton H. Bloom in 1970, is a space-efficient probabilistic data structure that is used to test whether an element is a member of a set. False positives are possible, but false negatives are not. Elements can be added to the set, but not removed (though this can be addressed with a counting filter). The more elements that are added to the set, the larger the probability of false positives.

For example, one might use a Bloom filter to do spell-checking in a space-efficient way. A Bloom filter to which a dictionary of correct words has been added will accept all words in the dictionary and reject almost all words which are not, which is good enough in some cases. Depending on the false positive rate, the resulting data structure can require as little as a byte per dictionary word.

In the last few years Bloom filter become hot topic again and there were several modifications and improvements. In this talk I will present my last few improvements in this topic.

The Bloom filter

RRDtool is the OpenSource industry standard, high performance data logging and graphing system for time series data. Use it to write your custom monitoring shell scripts or create whole applications using its Perl, Python, Ruby, TCL or PHP bindings.

RRDtool

Cascading is a large dataset build tool and a processing API for Hadoop.

Cascading

Skip graphs are a novel distributed data structure, based on skip lists, that provide the full functionality of a balanced tree in a distributed system where resources are stored in separate nodes that may fail at any time. They are designed for use in searching peer-to-peer systems, and by providing the ability to perform queries based on key ordering, they improve on existing search tools that provide only hash table functionality. Unlike skip lists or other tree data structures, skip graphs are highly resilient, tolerating a large fraction of failed nodes without losing connectivity. In addition, constructing, inserting new nodes into, searching a skip graph, and detecting and repairing errors in the data structure introduced by node failures can be done using simple and straightforward algorithms.

Skip graphs

As E. B. White said, "good writing is rewriting." I didn't realize this when I was in school. In writing, as in math and science, they only show you the finished product. You don't see all the false starts. This gives students a misleading view of how things get made.

A Version 1.0

Johnny Lee demos his amazing Wii Remote hacks, bending the $40 game part so it powers a digital whiteboard, a multitouch display and a head-mounted 3-D viewer. A multi-ovation demo from TED2008.

Johnny Lee's Wii Remote hacks

The following audio is a recording of last nights conversation at the ICA between Clay Shirky and Brian Eno, musician, artist and co-founder of the Long Now Foundation.

Everywhere we look, it seems, companies and organisations are trying to harness the alleged wisdom of crowds – the power of groups of people to come together through the internet and share with one another, work together, or take some kind of collective public action. One of the world’s leading experts on social and technological networking, Clay Shirky, Professor in the Interactive Telecommunications Program at New York University and the author of Here Comes Everybody: The Power of Organising without Organisations, comes to the ICA to talk about how the idea of networks, and particularly online social networks, is changing everything around us.

The Power of Networks