Well, except we know that gamma ray bursts regularly occur in our galaxy. The question is whether or not one occured close to our planet 450 million years ago.
Woah, that's pretty cool. It's funny... I once used DDR steps once to explain the basic swing dancing steps to my game-playing friends, before they went swing dancing for the first time.
Abstract: Presents an approach to generating biometric hash values based on statistical features in online signature signals. Whilst the output of typical online signature verification systems are threshold-based true-false decisions, based on a comparison between test sample signals and sets of reference signals, our system responds to a signature input with a biometric hash vector, which is calculated based on an individual interval matrix. Especially for applications, which require key management strategies, hash values are of great interest, as keys can be derived directly from the hash value, whereas a verification decision can only grant or refuse access to a stored key. Further, our approach does not require storage of templates for reference signatures, thus increases the security of the system. In our prototype implementation, the generated biometric hash values are calculated on a pen-based PDA and used for key generation for a future secure data communication between a PDA and a server by encryption. First tests show that the system is actuality able to generate stable biometric hash values of the users and although the system was exposed to skilled forgeries, no test person was able to reproduce another subject's hash vector.
Neat model of aspects of consciousness
on
Mapping the Mind
·
· Score: 2, Interesting
Finally, our most unique and advanced feature -- consciousness -- is explained. Carter describes the "working memory" model developed by Alan Baddeley, where images and speech-based information is held for short time in a cache-like space, while the "central executive" part co-ordinates the information processing.
Coincidentally, today the journal PLoS Biology released an article, where researchers describe a neuronal model they've devised of certain aspects of consciousness.
In general, Stanislas Dehaene (one of the paper's authors) has some very cool publications on neuroscience, consciousness, cognition, and so forth. You can find them here.
Here's a quote from the aforementioned synopsis:
Have you ever walked smack into a parking meter or tripped over something on the sidewalk? Embarrassing as such incidents may be, they're the product of normal brain function. The brain is continuously bombarded with sensory information about the environment but perceives just a fraction of these inputs. The rest--pertinent details or not--is filtered out. It's thought that consciousness emerges from the activity of multiple spontaneous neural processors that run in parallel and connect to a higher order cognitive network that mediates the conscious perception. But this higher order network has limited processing capacity. That means if you're distracted, your brain can't accommodate additional sensory information, like "there's a parking meter in front of you, look out!"
To understand how spontaneous brain processing interacts with higher order cognition, Stanislas Dehaene and Jean-Pierre Changeux modeled the dynamic properties of brain activity with computer simulations. Their simulations show that while spontaneous brain activity sometimes facilitates processing, more often it competes with external stimuli for access to consciousness. Intriguingly, the results of the computer simulations very closely match physiological and psychophysical experimental data and thus shed new light on how intrinsic brain activity modulates conscious perception....
With higher vigilance states, weaker external stimuli are able to ignite the global workspace. But paying attention to one thing narrows your perceptive capacity. Once ignited by one stimulus, the network cannot consciously process any others. Dehaene and Changeux propose that spontaneous activity--which operates within an "anatomically distinct set of workplace neurons"--offers an organism a measure of autonomy relative to the external world. While this decoupling of internal thought and external stimuli does have its disadvantages--like that pesky parking meter--it also provides the opportunity for introspection and creativity, which the authors argue is likely to "play a crucial role in the spontaneous generation of novel, flexible behavior."
How so? Lasers generally don't go through bodies very well. Maybe if you had a laser shining from below and had a translucent dance floor, but that actually seems more difficult than just using LEDs.
Actually, I suppose maybe the lasers could go through bodies, but then you'd have other problems to deal with.
When I was at CMU, that's what the CS girls often said about the CS guys. Another saying goes: "Women at MIT/Caltech/CMU are like parking spaces. They're all either taken or handicapped."
I actually disagree with the saying myself, but it's certainly amusing.
Any bets on how long until a Tetris clone is implemented for this?
Apparently the panels also have pressure sensors on them -- that's so cool. It sounds they have the hardware they need for an awesome game of massively-multiplayer Twister or Mosh Mosh Revolution. Variants of pinball, pong, or arkanoid could also be fun, with virtual paddles drawn wherever there were two nearby pressure points (i.e. feet).
How about the fact that we've lost almost 50% of all types of tropical, mediterranean and temperate forests as well as 30% of deserts over the past 100 years.
I'm under the impression that Chapline's view that black holes do not exist is a minority view in astrophysics. If he were correct though, I guess you'd then have to change the sentence to "Gamma ray bursts are thought to be caused either when two neutron stars collide or when giant stars collapse into dark energy stars at the end of their lives."
A pre-print of the research article is available. The impression that I get is that they don't claim to really "prove" the idea, but rather pose it as a very interesting hypothesis which is compatible with the evidence and deserves further investigation. In particular, I think their claim is that gamma ray bursts can explain the evidence of rapid cooling from the extinction period. Of course, the popular press claims this tentative hypothesis like it was already a concrete fact, but that's what the press does.
Here's the basic info:
Title: Did a gamma-ray burst initiate the late Ordovician mass extinction?
Abstract: Gamma-ray bursts (hereafter GRB) produce a flux of radiation detectable across the observable Universe, and at least some of them are associated with galaxies. A GRB within our own Ggalaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur on average two or more times per billion years. At least five times in the history of life, the Earth experienced mass extinctions that eliminated a large percentage of the biota. Many possible causes have been documented, and GRB may also have contributed. The late Ordovician mass extinction approximately 440 million years ago may be at least partly the result of a GRB. A special feature of GRB in terms of terrestrial effects is a nearly impulsive energy input of order 10 s. Due to expected severe depletion of the ozone layer, intense solar ultraviolet radiation would result from a nearby GRB, and some of the patterns of extinction and survivorship at this time may be attributable to elevated levels of UV radiation reaching the Earth. In addition a GRB could trigger the global cooling which occurs at the end of the Ordovician period that follows an interval of relatively warm climate. Intense rapid cooling and glaciation at that time, previously identified as the probable cause of this mass extinction, may have resulted from a GRB.
Granted, this could completely destroy the human race, but either way I'm dead, so my stake in it is over.
I suppose this is a philosophical difference, but as I see it, if I die there will still be people who remember me, carry some of my genes, and care about the same things and people that I do. I'd be dead, but bits of me would live on through other people. If the human race goes kaput, that all goes away.
I'm sure the guys at MIT are studying 'Real Genius' with great intensity as we speak, looking for revenge tactics.
Ah, but according to the rules, pranks should be original and not mere repeats of old ones. Many/most of the pranks from the movie Real Genius were based on real things which happened at Caltech.
Because most slashdotters probably won't actually browse around the site, I think it's important to repeat some of the rules of this prank war. The intent of this is good-natured fun, which seems to be missed by some of the commenters here.
Both Caltech and MIT require that students put in a lot of hard work studying math and science. Because the stress is so intense, we students at Caltech believe that pranks are an important, if not essential, way to relax and have a little fun. We are familiar with MIT's tradition of hacks and hope that we can merge the cultures at the two schools, if only for a short time.
We propose that MIT joins us in a pranking/hacking war. As you may have already noticed, we struck first, so now it is MIT's turn. Obviously the distance between schools poses a great difficulty, but we believe that MIT students will find that this difficulty can be overcome. In fact all of the pranks need not even be on the other school's campus so long as the pranks are made public enough through the media.
The rules of the contest are simple and are essentially the same as Caltech's prank ethics and MIT's hackers' code. Pranks should be reversible. No permanent damage should be done and the pranksters must provide some sort of contact information on a note so they can be contacted if things are damaged. The note need not contain names, but it must be a reliable way to contact the pranksters.
Pranks should be creative and display some form of originality. Novel ideas, particularly novel ideas involving technology, are generally well received, but repeats are strictly discouraged. We suggest that those wanting to participate make themselves very familiar with the history of pranks and hacks at both schools in order to prevent repeating pranks.
Finally, we wish to inform MIT students that Caltech Prefrosh Weekend is next weekend. It may not be possible to organize something so quickly, but we have faith in the ingenuity of MIT students. We hope to see you all in Pasadena soon.
As a side note, denial of service attacks are lame. Anybody can do that. Wouldn't your time be better spent trying to put a '2' on the scoreboard?
A situation where people in group A compete in their minds with people in group B, while the people in group B are barely aware group A exists and would laugh at the idea of competing with them if they thought about it. Examples: Harvard vs. MIT, CalTech vs. MIT, Linux vs. Microsoft.
As I understand it, there's a series of one-way rivalries which goes something like so: Harvard targeted by MIT, which is targeted by Caltech, which is targeted by Harvey Mudd. Members of the targeted school are largely oblivious that they're the subject of said rivalry.
Hopefully getting this on the slashdot front page (which is widely read by folks at both Caltech and MIT) might escalate the current prank war. It should be fun to have an active prank trade-off going between both MIT and Caltech. Hopefully people have a lot of frequent flyer miles.
I have no idea how the Caltech students managed to find the free time for this, though. Maybe they're all seniors or something?
With this 3D computer simulation coupled with realtime force feedback, an AFM can become a nanomanipulation tool where a user can interact with nano-size particles as easily as if they were lagre objects on the desk in front of them. This expands the utility of the AFM from simply a scanning device to a manufactuing tool with which we can assemble structures which are virtually impossible to build presently. Furthermore this system will allow novice users with little training to utilize the advanced capabilities of the system.
Fittingly, at a space elevator conference last month [September 2003] in New Mexico, the keynote speaker was Clarke, 86, who spoke via satellite. "I do think it may be the way to space. The economics are fantastic . . . I think it'll be built 10 years after everybody stops laughing . . . and I think they have stopped laughing."
Look the longest Nanotube is about 2 mm. (I've seen them and know the student making them.)
A couple of millimeters was the record in 2003. As of September 2004, the longest was 4 centimeters. What will the record be for 2005? 2006? 2010? 2020?
In 2004 Alan Windle's group of scientists at the Cambridge-MIT Institute developed a way to make carbon nanotube fiber continuously at the speed of several centimetres per second just as nanotubes are produced. One thread of carbon nanotubes was more than 100 metres long. The resulting fibers are electrically conductive and as strong as ordinary textile threads.
Granted, these continuously-spun variants don't have the required strength yet, but I think it's still a little early to call all of this outright stupid.
MIT's Blaise Gassend has a space elevator simulation available, which produces some rather neat animations of what happens when a space elevator breaks. It might be good as the basis for a more elaborate project.
Following is a modified version of a submission from last month, relevant to this discussion. I believe Edwards' group is planning on competing in the competition. Hopefully congress will lift the $250K prize restriction, allowing NASA to award larger prizes and truly stimulate research in this area:
MSNBC, Space.com, and Wired report that NASA, in collaboration with the non-profit Spaceward Foundation, has announced its first two Centennial Challenges. The Centennial Challenges, inspired by the Ansari X Prize and DARPA Grand Challenge, are prize contests seeking to stimulate private industry development of technologies relevant to space exploration. One contest is the Tether Challenge, for building the sort of super-strong tether needed to make a space elevator feasible. The other is the Beam Power Challenge, for creating a wirelessly-powered ribbon-climbing robot capable of lifting as large a payload as possible within a limited timeframe. The initial set of challenges in 2005 will award $50K to the winners of each contest. A second set of challenges in 2006 will award first, second, and third place prizes worth $100K, $40K, and $10K. It's hoped that these contests will further space elevator technology and help eliminate the 'giggle factor' surrounding them. Additional contests will be announced in the coming weeks, although Congress currently restricts NASA from awarding prizes of more than $250K; the agency is lobbying to try to get this limit raised to $40 million for future prizes.
Slashdot Mirror
Well, except we know that gamma ray bursts regularly occur in our galaxy. The question is whether or not one occured close to our planet 450 million years ago.
Thanks. What is the graph showing? Is it land area, number of species, or something else?
Well, yes I have been to clubs. My impression was that people would indeed mind very much if a laser sliced through their flesh.
Woah, that's pretty cool. It's funny... I once used DDR steps once to explain the basic swing dancing steps to my game-playing friends, before they went swing dancing for the first time.
Single-step:
left-hold, right-hold, down-right
repeat
Triple-step
left-right-left, right-left-right, down-right
repeat
http://scholar.google.com/scholar?q=biometric+hash
First result:
Biometric hash based on statistical features of online signatures
Vielhauer, C. Steinmetz, R. Mayerhofer, A.
Abstract: Presents an approach to generating biometric hash values based on statistical features in online signature signals. Whilst the output of typical online signature verification systems are threshold-based true-false decisions, based on a comparison between test sample signals and sets of reference signals, our system responds to a signature input with a biometric hash vector, which is calculated based on an individual interval matrix. Especially for applications, which require key management strategies, hash values are of great interest, as keys can be derived directly from the hash value, whereas a verification decision can only grant or refuse access to a stored key. Further, our approach does not require storage of templates for reference signatures, thus increases the security of the system. In our prototype implementation, the generated biometric hash values are calculated on a pen-based PDA and used for key generation for a future secure data communication between a PDA and a server by encryption. First tests show that the system is actuality able to generate stable biometric hash values of the users and although the system was exposed to skilled forgeries, no test person was able to reproduce another subject's hash vector.
Finally, our most unique and advanced feature -- consciousness -- is explained. Carter describes the "working memory" model developed by Alan Baddeley, where images and speech-based information is held for short time in a cache-like space, while the "central executive" part co-ordinates the information processing.
...
Coincidentally, today the journal PLoS Biology released an article, where researchers describe a neuronal model they've devised of certain aspects of consciousness.
Synopsis (for the layman): Assessing Consciousness: Of Vigilance and Distractedness
Research paper: Ongoing Spontaneous Activity Controls Access to Consciousness: A Neuronal Model for Inattentional Blindness
In general, Stanislas Dehaene (one of the paper's authors) has some very cool publications on neuroscience, consciousness, cognition, and so forth. You can find them here.
Here's a quote from the aforementioned synopsis:
Have you ever walked smack into a parking meter or tripped over something on the sidewalk? Embarrassing as such incidents may be, they're the product of normal brain function. The brain is continuously bombarded with sensory information about the environment but perceives just a fraction of these inputs. The rest--pertinent details or not--is filtered out. It's thought that consciousness emerges from the activity of multiple spontaneous neural processors that run in parallel and connect to a higher order cognitive network that mediates the conscious perception. But this higher order network has limited processing capacity. That means if you're distracted, your brain can't accommodate additional sensory information, like "there's a parking meter in front of you, look out!"
To understand how spontaneous brain processing interacts with higher order cognition, Stanislas Dehaene and Jean-Pierre Changeux modeled the dynamic properties of brain activity with computer simulations. Their simulations show that while spontaneous brain activity sometimes facilitates processing, more often it competes with external stimuli for access to consciousness. Intriguingly, the results of the computer simulations very closely match physiological and psychophysical experimental data and thus shed new light on how intrinsic brain activity modulates conscious perception.
With higher vigilance states, weaker external stimuli are able to ignite the global workspace. But paying attention to one thing narrows your perceptive capacity. Once ignited by one stimulus, the network cannot consciously process any others. Dehaene and Changeux propose that spontaneous activity--which operates within an "anatomically distinct set of workplace neurons"--offers an organism a measure of autonomy relative to the external world. While this decoupling of internal thought and external stimuli does have its disadvantages--like that pesky parking meter--it also provides the opportunity for introspection and creativity, which the authors argue is likely to "play a crucial role in the spontaneous generation of novel, flexible behavior."
How so? Lasers generally don't go through bodies very well. Maybe if you had a laser shining from below and had a translucent dance floor, but that actually seems more difficult than just using LEDs.
Actually, I suppose maybe the lasers could go through bodies, but then you'd have other problems to deal with.
Actually, DDR experience came quite handy when later on I started learning things like swing dancing.
When I was at CMU, that's what the CS girls often said about the CS guys. Another saying goes: "Women at MIT/Caltech/CMU are like parking spaces. They're all either taken or handicapped."
I actually disagree with the saying myself, but it's certainly amusing.
Any bets on how long until a Tetris clone is implemented for this?
Apparently the panels also have pressure sensors on them -- that's so cool. It sounds they have the hardware they need for an awesome game of massively-multiplayer Twister or Mosh Mosh Revolution. Variants of pinball, pong, or arkanoid could also be fun, with virtual paddles drawn wherever there were two nearby pressure points (i.e. feet).
How about the fact that we've lost almost 50% of all types of tropical, mediterranean and temperate forests as well as 30% of deserts over the past 100 years.
Do you happen to have a citation for that?
I'm under the impression that Chapline's view that black holes do not exist is a minority view in astrophysics. If he were correct though, I guess you'd then have to change the sentence to "Gamma ray bursts are thought to be caused either when two neutron stars collide or when giant stars collapse into dark energy stars at the end of their lives."
That wasn't too hard now, was it?
A pre-print of the research article is available. The impression that I get is that they don't claim to really "prove" the idea, but rather pose it as a very interesting hypothesis which is compatible with the evidence and deserves further investigation. In particular, I think their claim is that gamma ray bursts can explain the evidence of rapid cooling from the extinction period. Of course, the popular press claims this tentative hypothesis like it was already a concrete fact, but that's what the press does.
Here's the basic info:
Title: Did a gamma-ray burst initiate the late Ordovician mass extinction?
Abstract: Gamma-ray bursts (hereafter GRB) produce a flux of radiation detectable across the observable Universe, and at least some of them are associated with galaxies. A GRB within our own Ggalaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur on average two or more times per billion years. At least five times in the history of life, the Earth experienced mass extinctions that eliminated a large percentage of the biota. Many possible causes have been documented, and GRB may also have contributed. The late Ordovician mass extinction approximately 440 million years ago may be at least partly the result of a GRB. A special feature of GRB in terms of terrestrial effects is a nearly impulsive energy input of order 10 s. Due to expected severe depletion of the ozone layer, intense solar ultraviolet radiation would result from a nearby GRB, and some of the patterns of extinction and survivorship at this time may be attributable to elevated levels of UV radiation reaching the Earth. In addition a GRB could trigger the global cooling which occurs at the end of the Ordovician period that follows an interval of relatively warm climate. Intense rapid cooling and glaciation at that time, previously identified as the probable cause of this mass extinction, may have resulted from a GRB.
Granted, this could completely destroy the human race, but either way I'm dead, so my stake in it is over.
I suppose this is a philosophical difference, but as I see it, if I die there will still be people who remember me, carry some of my genes, and care about the same things and people that I do. I'd be dead, but bits of me would live on through other people. If the human race goes kaput, that all goes away.
IMHO, MIT's R2D2 Great Dome Hack was pretty cool, and that was just a few years ago.
I'm sure the guys at MIT are studying 'Real Genius' with great intensity as we speak, looking for revenge tactics.
Ah, but according to the rules, pranks should be original and not mere repeats of old ones. Many/most of the pranks from the movie Real Genius were based on real things which happened at Caltech.
Because most slashdotters probably won't actually browse around the site, I think it's important to repeat some of the rules of this prank war. The intent of this is good-natured fun, which seems to be missed by some of the commenters here.
From http://www.caltechvsmit.com/overview.html:
Both Caltech and MIT require that students put in a lot of hard work studying math and science. Because the stress is so intense, we students at Caltech believe that pranks are an important, if not essential, way to relax and have a little fun. We are familiar with MIT's tradition of hacks and hope that we can merge the cultures at the two schools, if only for a short time.
We propose that MIT joins us in a pranking/hacking war. As you may have already noticed, we struck first, so now it is MIT's turn. Obviously the distance between schools poses a great difficulty, but we believe that MIT students will find that this difficulty can be overcome. In fact all of the pranks need not even be on the other school's campus so long as the pranks are made public enough through the media.
The rules of the contest are simple and are essentially the same as Caltech's prank ethics and MIT's hackers' code. Pranks should be reversible. No permanent damage should be done and the pranksters must provide some sort of contact information on a note so they can be contacted if things are damaged. The note need not contain names, but it must be a reliable way to contact the pranksters.
Pranks should be creative and display some form of originality. Novel ideas, particularly novel ideas involving technology, are generally well received, but repeats are strictly discouraged. We suggest that those wanting to participate make themselves very familiar with the history of pranks and hacks at both schools in order to prevent repeating pranks.
Finally, we wish to inform MIT students that Caltech Prefrosh Weekend is next weekend. It may not be possible to organize something so quickly, but we have faith in the ingenuity of MIT students. We hope to see you all in Pasadena soon.
As a side note, denial of service attacks are lame. Anybody can do that. Wouldn't your time be better spent trying to put a '2' on the scoreboard?
Caltech is a small (no, tiny) campus, and that one server fire could take the entire place out by morning.
;)
Nah, I'm pretty sure Caltech's Segway police will be able to quickly respond to put out the fire.
As I understand it, there's a series of one-way rivalries which goes something like so: Harvard targeted by MIT, which is targeted by Caltech, which is targeted by Harvey Mudd. Members of the targeted school are largely oblivious that they're the subject of said rivalry.
Hopefully getting this on the slashdot front page (which is widely read by folks at both Caltech and MIT) might escalate the current prank war. It should be fun to have an active prank trade-off going between both MIT and Caltech. Hopefully people have a lot of frequent flyer miles.
I have no idea how the Caltech students managed to find the free time for this, though. Maybe they're all seniors or something?
Yup. However, there is research into things sort of like what Stephenson described. One example:
TeleNano Project: Augmented Reality User Interface for Atomic Force Microscopes (afm)
With this 3D computer simulation coupled with realtime force feedback, an AFM can become a nanomanipulation tool where a user can interact with nano-size particles as easily as if they were lagre objects on the desk in front of them. This expands the utility of the AFM from simply a scanning device to a manufactuing tool with which we can assemble structures which are virtually impossible to build presently. Furthermore this system will allow novice users with little training to utilize the advanced capabilities of the system.
article
Fittingly, at a space elevator conference last month [September 2003] in New Mexico, the keynote speaker was Clarke, 86, who spoke via satellite. "I do think it may be the way to space. The economics are fantastic . . . I think it'll be built 10 years after everybody stops laughing . . . and I think they have stopped laughing."
Look the longest Nanotube is about 2 mm. (I've seen them and know the student making them.)
e nt_progress
A couple of millimeters was the record in 2003. As of September 2004, the longest was 4 centimeters. What will the record be for 2005? 2006? 2010? 2020?
Wikipedia also states the following:
http://en.wikipedia.org/wiki/Carbon_nanotube#Curr
In 2004 Alan Windle's group of scientists at the Cambridge-MIT Institute developed a way to make carbon nanotube fiber continuously at the speed of several centimetres per second just as nanotubes are produced. One thread of carbon nanotubes was more than 100 metres long. The resulting fibers are electrically conductive and as strong as ordinary textile threads.
Granted, these continuously-spun variants don't have the required strength yet, but I think it's still a little early to call all of this outright stupid.
MIT's Blaise Gassend has a space elevator simulation available, which produces some rather neat animations of what happens when a space elevator breaks. It might be good as the basis for a more elaborate project.
GPL'd source code
Following is a modified version of a submission from last month, relevant to this discussion. I believe Edwards' group is planning on competing in the competition. Hopefully congress will lift the $250K prize restriction, allowing NASA to award larger prizes and truly stimulate research in this area:
MSNBC, Space.com, and Wired report that NASA, in collaboration with the non-profit Spaceward Foundation, has announced its first two Centennial Challenges. The Centennial Challenges, inspired by the Ansari X Prize and DARPA Grand Challenge, are prize contests seeking to stimulate private industry development of technologies relevant to space exploration. One contest is the Tether Challenge, for building the sort of super-strong tether needed to make a space elevator feasible. The other is the Beam Power Challenge, for creating a wirelessly-powered ribbon-climbing robot capable of lifting as large a payload as possible within a limited timeframe. The initial set of challenges in 2005 will award $50K to the winners of each contest. A second set of challenges in 2006 will award first, second, and third place prizes worth $100K, $40K, and $10K. It's hoped that these contests will further space elevator technology and help eliminate the 'giggle factor' surrounding them. Additional contests will be announced in the coming weeks, although Congress currently restricts NASA from awarding prizes of more than $250K; the agency is lobbying to try to get this limit raised to $40 million for future prizes.
As long as youre wearing a spacesuit theres no reason why you couldn't base jump off to escape...
It's sometimes referred to as spacediving.