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Lorna Mills and Sally McKay

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In honor of the death of LimeWire we have stolen a "brief history of some of the biggest events in file sharing over the past ten years" from Gearlog. (warning: annoying pop-ups)

LimeWire went dark today, thanks to a court-ordered injunction. The Manhattan-based site is just the latest in a long line of file-sharing sites to rise and fall in the past decade or so.

In honor of the death of LimeWire, here's a brief history of some of the biggest events in file sharing over the past ten years.

1999: Napster Released
An 18-year-old student at Boston's Northeastern University launches a file sharing service, branding it with his childhood nickname. The service catches fire quickly and almost immediately catches the attention of the Recording Industry Association of America and vocal anti-file sharing musicians like Metallica's Lars Ulrich.

2000: Gnutella Launches
This popular peer-to-peer network was initially launched by AOL-owned Nullsoft. AOL shut down the program, thanks to file sharing concerns, but it was too late--the client was already out.

2000: LimeWire Launches
The site is launched by Mark Gorton, a former Wall Street trader with degrees from Harvard, Yale, and Stanford. Like many other P2P creators before and since, Gorton has long insisted that the existence of his site is well within the confines of the law.

2001: Napster Shuts Down
A heated legal battle between Napster and the RIAA ends in March with an injunction against the site. Napster shuts down its network in July, declares bankruptcy, and is later reborn as a legal music subscription service in 2001.

2001: Kazaa Launches
Designed by programmers in Estonia, this service is quickly snapped up by Niklas Zennström and Janus Friis, the duo who, three years later, will help launch Skype. Kazaa is the target of legal battles in a number of countries and a number of users are subjected to heavy record industry fines.

2001: BitTorrent is Released
This popular file sharing protocol fills in the void for users seeking a Napster replacement, accounting for nearly half of Web traffic at the height of its popularity, and giving rise to a number of popular services: The Pirate Bay, and isoHunt

2003: The Pirate Bay Launch
Swedish anti-copyright organization Piratbyrån (The Piracy Bureau) launched this BitTorrent indexer. It becomes one of the most popular sites on the Internet, and is subsequently subject to various police raids. In 2007, it attempted to by its own tiny island nation to avoid litigation.

2006: Kazaa Fined, Goes Legit
In July, the site is ordered to pay $100 million in damages to the record industry. Like Napster before it, the site is purchased by new owners and re-launched as a legal service.

2010: Court Ordered Pirate Bay Injunction
Once again, Pirate Bay is taken down due to a court-ordered injunction, only to return again shortly after, earning its slogan, "The world's most resilient bittorrent site."

2010: LimeWire Closes
Thanks to a permanent injunction issued by a New York-based federal court, LimeWire becomes the latest P2P casualty.

The Talairach Atlas

Wikipedia says: "By defining standard anatomical landmarks that could be identified on different subjects (the anterior and posterior commissures), it became easier to spatially warp an individual brain image obtained through Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET) and other imaging methods to this 'standard Talairach space'. One can then make inferences about tissue identity at a specific location by referring to the atlas."

Everything2 says:" There are some problems with the Talairach atlas. First of all, the atlas is based on one brain, which happens to be the brain of a 60-year-old French woman. Only one hemisphere was mapped, assuming that the hemispheres were symmetrical (although as a rule they are not). The most notable difference between the Talairach brain and other brains is its size. The Talairach brain is considerably smaller than the average brain by up to 10 millimeters in each dimension. Because brain sections are typically taken every 2 millimeters, this leaves a total of 15 slices that would go unnaccounted for. Also, the Talairach atlas leaves out the majority of the brain stem and cerebellum."

9 different people's brains, aligned at the thalamus.

9 brains

A few weeks ago I made a post about fMRI. This is another one. I'm currently auditing a class called "Introduction to fMRI." Disclaimer in case anyone winds up here because they are looking for actual neuroscience: I'm not a scientist and I don't have a fucking clue what I am doing! I'm trying my best, but I suggest you do not quote me.

Detail from autopsy photo of a human brain at Wikimedia (cropped and enlarged).

fMRI is a digital imaging challenge extraordinaire. Two of the biggest concerns are resolution and signal to noise ratio. The image above is a photograph showing some of the vasculature on the surface of the brain. fMRI measures something called the blood-oxygen-level dependent (BOLD) effect. In very simple terms, when synaptic action happens between neurons the process requires energy, and blood provides the fuel. So when a certain area of the brain is busy, blood will concentrate there. The nuclear processes ("spinning" protons) activated and detected by the scanner happen in the blood flow that correlates to the synaptic activity, not in the neurons themselves. Happily, the network of veins and arteries is extremely fine and precise — maintaining a discrete structure right down to level of individual blood vessels — so the vasculature itself doesn't limit the resolution of the scan.

The BOLD effect takes place over time, as blood flows in and out.
The signal tends to look like this.
BOLD response signal

And this is why.
BOLD response diagram

The useful amount of signal is limited by the time scale of the BOLD response. Also, there are issues of pooling in nearby veins when the blood recedes that can cause noise. Deciding on resolution is a balancing act. The smaller you make your voxels the more precisely you can localise the effects, but you will also have a weaker signal because is less blood to measure per unit. And you want a strong signal because there can be a TON of noise. Head movements cause a lot of noise, as well as inconsistencies in the magnetic field that can be caused by the scanner itself, the morphology of the person's brain, and thingies in the blood. It's very easy to get false positives. So the size of your voxels needs to be large enough that you get a strong signal, but small enough that the signal isn't completely full of junk.

The scanner detects the entire electro-magnetic signal coming from each voxel. You might be looking for something like this.
signal pure

But you are quite likely to get something more like this.
signal noisy

Which means its pretty easy to wind up with an fMRI image showing false positives unless you are very careful with your data.

For more on Craig Bennett's dead salmon, see this post from last year.

Also, of course, different brain activities take different amounts of time. So you also need to consider how long your activation signal will be, based on the experiment. Some brain processes that take more than a few seconds to happen just aren't that amenable to being measured by fMRI.

And then there are the problems of "normalization" across different test subjects. Everybody's brain is different. So some noise is going to enter into your data when you start trying to combine information from different people into one stream. More on this coming soon...

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