Domain: dal.ca
Stories and comments across the archive that link to dal.ca.
Comments · 72
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as an evolutionary biologist....
Treefinder has been dead for about a decade. If youre still using im surprised you have enough data from it to continue a grant proposal, but i hope you'll consider other more functional applications like PHYLIP PAUP MEGA Phylo_win ARB or DAMBE
hybridization or recombination events got you down? concaterpillar to the rescue. http://rogerlab.biochemistryan...
distance matrix analyses on nucleotide or protein sequences? seriously, get a copy of ODIN. while i couldnt get funding for a beefier desktop, i DID get compute time on our university supercomputer and ODIN absolutely screams on linux. -
Re:Supply and demand.
I don't think price is what keeps people from owning guns. It's rather that they are risk-averse to accidents, or maybe just think they're icky, or don't want legal problems from an unregistered gun. Cheaper and more available won't change most of this. You can already buy a crappy pistol for under $200. This is not a huge problem even for the relatively poor.
Also, 3d-printing is not a replicator. You still have quite a bit of work assembling it (and buying ammo), which is probably hard to do if you're in a homicidal rage.
Suicides would probably increase, since they are 1) planned, 2) planned mostly by people who are depressed enough to be put off by substantial challenges. I would guess homicides wouldn't increase much.
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Re:Someone forgot to tell these guys
Even more importantly, this ignores a previous published article on "DNA Sequence from Cretaceous Period Bone Fragments" -- Science 266 (5188) 1229-1232, here is a PDF of the article in Science. Either 80 mya (Cretaceous) is horribly wrong, the 521 year half-live of DNA is horribly wrong, Woodruff, et al were horrible deceived (or frauds) or some combination of these.
You would hope evidence would be the deciding factor, but scientists are human too, and the interpretation of evidence is often more important than the actual evidence -- it is very hard to upset to prevailing opinion (as it should be when the opinion is well founded)
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Re:Not a problem
Oh my! You are a father?
And you don't even bother with a quick search to double check if maybe your initial statements might be false.
Two minutes of web search:
http://www.apa.org/research/action/protect.aspx
http://www.apa.org/news/press/releases/2003/03/media-violence.aspx
http://onlinelibrary.wiley.com/doi/10.1111/j.1540-4560.1986.tb00246.x/abstract
http://mediasmarts.ca/backgrounder/kids-net-seven-and-eight-year-olds
http://www.psychologicalscience.org/media/releases/pr040527.cfm
BTW I am not concerned about simple nudity or a normal sex act, it is very specifically the mixture of aggression and sex that is most concerning. That is why I repeatedly cited "Fisting" and "Ball Torture".
Your comment has certainly ruined my day and is very depressing. I originally chalked this nonsense up to teenage immaturity. If you are in fact a parent and yet so proudly display your ignorance on this topic, then this is disturbing on many levels.
And yes, you are also entirely wrong about learning. You are essentially negating decades of neurological, psychological, AI and educational research. The key here is how category learning works and the path towards more abstract thought processes.
Don't think though that any of this will penetrate you pre-conceived notion.
http://www.encyclopedia.com/doc/1G2-3403200097.html
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opendx
good luck with that.... as a coder i'd just use opendx, make it work properly(not an easy task), and show some results quickly, less effort and you will have fun with the data.
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a few years?
like, just before 1945?
http://cneh09.dal.ca/Schenk_CNEH.pdf -
Re:FreeBSD might prove benefical
FreeBSD has worked very well on our cluster.
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Re:git objects don't live in a vacuum
Here is a collection of real world implementations of a collision attacks in which two legitimate executable binaries were created to have the same MD5 hash and size.
Here is the post script collision attack that Omnifarious was referring to. Both files are the same length and have the same MD5 hash. Furthermore, postscript is a turing complete programing language, with as picky of a syntax as C.
All the collision attacks I have seen used fixed length blocks in both files which are modified. Inserting a fixed length comment block into a piece of code is not hard.
Preimage attacks (where you only modify one file not both) are harder, and to date, not even MD5 has any known practical preimage attacks. But if it did, it would be trivial to implement it by tweaking a block comment in a source code file, or a data segment in a binary file. There is no challenge there whatsoever.
It took me less than a minute to find those on Google. I don't expect people to know everything, but if you are going to run around insulting people and being an asshole, you better know what the fuck you are talking about.
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Re:Why drag the city along when land is cheap?
Plus, they really like seafood. This city could follow the fish.
Until they run out of fish. Then they would have nowhere to go.
Then hurry! There's not much time left.
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Re:With that little side benifit...
It's dangerous to go alone. Take this.
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Re:So let's change the algorithm.
Really? Are you familiar with MD5 collisions?
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Re:Hash Collisions
I have an idea for an attack vector.
Say File A is one block big. File A is publicly available on the server, not writable by users. Eve produces a SHA256 hash collision of file A and stores this file B in ~. Someone wants to retrieve file A but gets file B (e.g. like evilize exe for MD5).
Alternatively, if always the oldest file is kept, Eve has to know the next version of the file.Given big blocks and time until cryptoanalysis for SHA256 is at the state of where it is with MD5, why not?
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Don't trust MD5 either...
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Re:overwritten once CAN be recovered
That can be a dangerous way of thinking. Suppose that several years ago, you designed a system that relied on the MD5 algorithm for life-critical security on several fronts. After all, since there were no techniques at the time to compromise MD5, you didn't believe it could be done so it was perfectly safe.
Fast forward to 2005. MD5 is broken. Updating your system to use SHA1 is either impossible or would take far too long. Hackers exploit your high-profile system. Santa Claus falls down your chimney.
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Right guy, right song, wrong story
Dr. Brown's work on the opening chord of Hard Day's Night is four years old. His paper is at:
http://www.mscs.dal.ca/~brown/n-oct04-harddayjib.pdf
(Note the "oct04" date in the URL).
His recent work is on the same song, but it's not about the opening chord. It's about the guitar solo (which was actually a duet with the piano), which Harrison played an octave down, at half speed, and then sped up. Which he proved by noticing where the piano notes went from double-strings to triple-strings, as seen by tiny mis-tunings between the strings.
It's pretty interesting work:
http://www.mscs.dal.ca/~brown/AHDNSoloJIB.pdf
(Note: slashdot is just reporting the article, which is new. But it comes from Dr. Brown's own school, so I don't know why they're reporting the wrong story, except to guess that the older story was a well-known mystery among guitarists.)
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Right guy, right song, wrong story
Dr. Brown's work on the opening chord of Hard Day's Night is four years old. His paper is at:
http://www.mscs.dal.ca/~brown/n-oct04-harddayjib.pdf
(Note the "oct04" date in the URL).
His recent work is on the same song, but it's not about the opening chord. It's about the guitar solo (which was actually a duet with the piano), which Harrison played an octave down, at half speed, and then sped up. Which he proved by noticing where the piano notes went from double-strings to triple-strings, as seen by tiny mis-tunings between the strings.
It's pretty interesting work:
http://www.mscs.dal.ca/~brown/AHDNSoloJIB.pdf
(Note: slashdot is just reporting the article, which is new. But it comes from Dr. Brown's own school, so I don't know why they're reporting the wrong story, except to guess that the older story was a well-known mystery among guitarists.)
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Re:So, having Googled...
There are like a million copies of this article verbatim and with the same picture. Here's his page http://www.mscs.dal.ca/~brown/
and then find these:
http://www.guitarplayer.com/story.asp?sectioncode=8&storycode=15819
http://www.mscs.dal.ca/~brown/AHDNSoloJIB.pdf -
Re:So, having Googled...
There are like a million copies of this article verbatim and with the same picture. Here's his page http://www.mscs.dal.ca/~brown/
and then find these:
http://www.guitarplayer.com/story.asp?sectioncode=8&storycode=15819
http://www.mscs.dal.ca/~brown/AHDNSoloJIB.pdf -
Re:MD5 Collisions...
Here's a link to some examples.
The postscript example is a dead link. It does have a pair of apps with the same MD5 sum, one of which is a "hello world" program and the other of which pretends to erase your hard drive. It also has a library for creating such programs on your own.
As far as I know, it's not yet practical to create a brand new file unrelated to an existing one which collides with that existing file's hash. So I can't create a file that hashes the same as your file, I can only create a pair of files that hash the same. However, this is only a matter of time.
MD5 is dead for cryptographic purposes, and the time to stop using it for that is yesterday.
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Re:MD5 Collisions...
Maybe you should read this two year old article on the subject.
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Re:Probably just for P2P
Better hope they don't use md5. Or, if you like to put people in prison, better hope they do.
File 1 could be child porn, File 2 could be some hot virus action. Which one will you be getting it on with tonight?
One thing's for sure! You'll be getting it on with Bubba in prison next week if you download either!
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Firefox 3, version 2.0.0.14
Oh very nice. It says 3 on the site now, but the version is still 2.0. The download link itself is rather amusing.
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Re:Censorship
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Re:MD5
The claim is true. Wang and Yu published it in 2005.
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Re:Wikipedia has more info about itIt is interesting to note that some of the design (not the neutron absorber Lithium-6) reminds me of the Canadian SLOWPOKE reactor, first built in the 1960's.
More about SLOWPOKE:
Damn those safe, smart Canadians. They might quietly run the world, or at least keep it running. -
Re:Actually buy one
This looks a LOT like digital inline holography, but I didn't see in the article what technique they're useing. I did some minor DIH work at Dalhousie University, back in 2004. Last I heard, a couple of the profs there are developing a commercial product.
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Landing animation and commentary
This animation from Maas Digital shows that the planned landing of Phoenix is very ambitious. As the spacecraft enters the Martian atmosphere it is protected by a heat shield. Notice the ice cap on the northern pole, which was constructed from images from the Mars Global Surveyor. A parachute will be used to slow the descent, but because the atmosphere is so thin, it will still be going *very* fast. You can see clouds in the background, which were also seen from orbit by MGS.
A key event happens after the parachute and heat shield rip away: the landing gear deploys, and then the retro-rockets kick in. One problem with the ill-fated Mars Polar Lander was that the sequence of the last two events was reversed. An on-board sensor felt a jolt as when the landing gear locked in and assumed that the landing had taken place. The engines were shut off and the spacecraft plummeted to ground. So close...
It is very difficult to test landing procedures here on Earth. The gravity on Mars is only a third of what we have, and a simulation is never as good as testing in realistic conditions.
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Re:Canadian Content
Yes, that's me. York is developing a nice space programme, which I am sure you are enjoying. I'm a York alumnus myself, and have collaborated with the Canadian lead on Phoenix (Jim Whiteway, York U) for a long time. I'm now at Dalhousie University, and you can read about our contribution to Phoenix at http://mars.dal.ca/.
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they'd better hurry
Cuz the world is rapidly running out.
Which also means we're next. -
Re:I'd like to say...
(btw, here's the best joke on the whole interweb: http://torch.cs.dal.ca/~hannon/ !)
That page seems to be broken. I went there and all I got was a black screen ;-) -
Re:I'd like to say...
I'd just like to point out: Digg is now 'Out of Service'
Here's proof: http://torch.cs.dal.ca/~hannon/digg_sux.jpg
(btw, here's the best joke on the whole interweb: http://torch.cs.dal.ca/~hannon/ !) -
Re:I'd like to say...
I'd just like to point out: Digg is now 'Out of Service'
Here's proof: http://torch.cs.dal.ca/~hannon/digg_sux.jpg
(btw, here's the best joke on the whole interweb: http://torch.cs.dal.ca/~hannon/ !) -
Re:Time for the "reinventthewheel" tag?
How well does it uncompress these two 128 byte files?
d131dd02c5e6eec4693d9a0698aff95c 2fcab58712467eab4004583eb8fb7f89
55ad340609f4b302 83e488832571415a 085125e8f7cdc99fd91dbdf280373c5b
d8823e3156348f5b ae6dacd436c919c6 dd53e2b487da03fd02396306d248cda0
e99f33420f577ee8 ce54b67080a80d1e c69821bcb6a8839396f9652b6ff72a70
d131dd02c5e6eec4693d9a0698aff95c 2fcab50712467eab4004583eb8fb7f89
(remove all the slashtrash spaces first..) Hint: The MD5 hash of both is 79054025255fb1a26e4bc422aef54eb4.
55ad340609f4b302 83e4888325f1415a 085125e8f7cdc99fd91dbd7280373c5b
d8823e3156348f5b ae6dacd436c919c6 dd53e23487da03fd02396306d248cda0
e99f33420f577ee8 ce54b67080280d1e c69821bcb6a8839396f965ab6ff72a70
See http://www.mscs.dal.ca/~selinger/md5collision/
My CRC-8 compression algorithm uses the same technique and beats your compression by a factor of 0x10! -
Re:They're different things
I've even seen such bullshit claims like that it basically holds all possible states at the same time, so it can calculate anything instantly, since the solution state is already one it simultaneously holds. Which is blatantly bull. If it simply holds all possible states at the same time, that's as good as saying that it has no state at all, or you can't measure it. To get an answer out of the computer, you need to get out of it a particular state which represents the result of the calculation. By that logic I could give you a CD with all possible 4 million DWORD (4 byte, 32 bit) values, from -2 million to 2 million, one of which is the result to your problem. There you go, any problem that has a DWORD result already has the result on that CD, so it was "calculated" instantly. Isn't it an impressive feat? I don't even know your problem, but that CD already has the result to it. It's also completely freakin' useless, if you don't know which one of them. That CD as such holds no more actual usable information that that it's a 32 bit number, which you knew in the first place.
I know little about quantum mechanics and have no clue about quantum computing, but being an expert in constraint-based problem solving perhaps I may throw some light on how this might actually work.
Automated reasoning and theorem proving are usually computed by performing inferences over a search space, defined by a problem stated in a declarative language. A way to represent this kind of problems is by defining a "raw" region of data (like your "All the possible DWORDS", and then asserting constraints over the data that all solutions must fulfil. A classic solver will then proceed to generate many candidate solutions one after another, testing whether they break one of the constraints.
As an example of how this strategy, think of the Eratostenes sieve - you have a pool of numbers in sequence, and want to find all primes. First you remove every second number (greater than 2), because you know those numbers are even; do the same to every third number, every fifth (4 is already removed), etc. This algorithm is not efficient in a classic computer because you have to loop number by number through every inference step.
The dream of every IA researcher and every parallel computer designer would be a way to test all generated candidate solutions at once, instead of looping through them one by one. Quantum computing, if works as advertised, would provide just that - they should implement flooding algorithms in which the computer follows all viable reasoning paths simultaneously, while the stated constraints prune all the forbidden states.
Since all followed paths are equally valid, it doesn't matter to which particular solution the system will collapse when finally observing the result. As the number of loops required to solve logic combinatorial problems grow exponentially, this could reduce the required time to linear, in many cases.
Practical quantum computers are still far away, if ever possible. But if they can work as I've described (and for what people are doing, they might work), they could represent an advance in the field as important as the transistor was to digital computers. -
Re:We know it's true
> OK, I just thought that the effort involved is non-standard (mileage varies).
Oh please. The authors' method -- meta-analysis -- is a very kind way to say they data-mined the literature and did statistical jiggery-pokery with it. Not that there's anything wrong with statistics, but there are are margins of error in each experiment he referenced. Now, the conclusions drawn -- that there is a trended loss of biodiversity -- is statistically supportable, but to go from here to a 'no fish by 2050' (or indeed no fish by fill-in-the-blanks-with-your-favorite-year) hypothesis -- something their press release encourages -- is irresponsible science, because small discrepancies in conditions in complex systems lead to wildly different results, and you can't make specific predictions of complex behavior based on statistical analyses of experimental data all of which have margins of error hidden in them.
> I thought (American English) this is an adverb and thus deserves a "-ly". But I am not about to indeed discuss this until you demonstrate equivalent aptitude in my mother tongue
That's funny, English isn't my first language either, it just happens to be one of the three I know. And I do make mistakes, however when my mistakes are pointed out I don't adopt a John Kerry-esque "I'm too smart to admit making a mistake" mentality, I learn from them: in this case, "Ironically, Worm was correct" is a reasonable use of an adverb, your use ("I am trying hard to not even sound ironically") isn't. Deal with it. -
Re:We know it's true
*Real* scientists who write for the record look into the original papers (linked from http://myweb.dal.ca/bworm/, a real intellectual endeavor to find) before commenting.
Real scientists are not primarily known by the fact that they 'look into the original papers'. If that were really the main work of real science, nothing new would ever be discovered. In fact, the truly essential element of real science is the original work of performing experiments and making nontrivial calculations.
Fortunately, no one ever required that you have to be a real scientist in order to shoot the breeze on slashdot. Well, except maybe you. -
Re:We know it's true
*Real* scientists who write for the record look into the original papers (linked from http://myweb.dal.ca/bworm/, a real intellectual endeavor to find) before commenting.
CC. -
Re:Apple has it coming
I beg to differ! See http://torch.cs.dal.ca/~hannon/windowlayers.jpg. Finder on top of Quicktime on top of Finder.
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Encryption software recommendations
You should encrypt it before sending it out to the service provider. This way you don't care, what method THEY are using. In fact, you'd rather they used none at all.
Personally, I am happy with CCrypt, which is a secure replacement for the simple-minded Unix crypt(1) utility. The FreeBSD port makes installing a breeze, as usual.
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Contraband Canadian toilets
So I know these Canadians who like to dress up like Klingons. They have trouble every time they try to cross the border, not because of their bat'leths, but because of something they call the Throne of Kahless. Here is a picture:
http://torch.cs.dal.ca/~pconnors/KAGPics//pic12.jp g
and pictures with descriptions here:
http://www.kagkanada.com/photos.html
As you can see, it's one of those contraband Canadian toilets. Well, it's never been used as a toilet, but as a giant punch bowl. And it's been mounted on a block of wood with a plaque. There's even a little roll of "Klingon toilet paper" attached, which is some sandpaper rolled around an empty tube. So it's definitely coming back to Canada after the party.
Try telling that to a customs agent.
Suffice it to say, customs agents may not stop the flow of guns or drugs that goes both ways across our border, but they sure do batprotect us all from high-flow toilets. Whew! -
peer-reviewed publications on passive detection
Vanderlaan, A.S.M., Hay, A.E., and Taggart, C.T., 2003. Characterization of North Atlantic right whale Eubalaena glacialis sounds in the Bay of Fundy. IEEE J. Oceanic Eng., 28(2), 164-173.
Laurinolli, M.H., Hay, A.E., Descharnais, F., and Taggart, C.T., 2003. Localization of North Atlantic right whale sounds in the Bay of Fundy using a sonobuoy array. Marine Mammal Science, 19(4), 708-723.
These papers (and others that are not yet published) come from a Physics-Biology interdisciplinary collaboration at Dalhousie University in Canada; for more see http://oceanography.dal.ca/index.html and follow links to get to Hay's (Physics) page or Taggart's (Biology) page.
This work has already led to policy changes, e.g the shipping lanes in the Bay of Fundy have been shifted, to try to reduce the probability of ships striking whales.
More work is needed, and not just on the acoustics. For example, we have no clear understanding of what happens when a ship strikes a whale at a given angle and closing speed, so it is impossible to make policy recommendations on the speed of ships in key areas. (It is undesirable to build up statistics by observing nature, because the right-whale population is on a path of extinction, so every individual matters.)
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FreeOFTE for Win/Lin or ccrypt for Mac/Win/Lin
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I'm not just a customer, I'm also an employee
I work for a major AV company, so feel free to take this with a grain of salt.
Don't waste your time dealing with the symptoms of these virus attacks. Do something about the source: Insecure Windows-based desktop PCs.
Get your school to purchase a site license for a computer security suite that has an anti-virus engine, anti-spyware engine, a firewall and remote administration. My alma mater is a McAfee customer. They use EPO to manage and push updates to every Windows machine on campus as well as to control the firewall settings. I'd expect that Symantec's offerings are similar.
If your university's IT department has any budget at all, it should be an easy sell. They will quickly recover the cost of the software licenses through bandwidth conservation and fewer support tickets related to infected machines. -
Re:Octopus!I've always envied people who have little tentacled friends, and for the first year and a half of university, I was studying biology in the hopes of someday working with the little guys. I switched to computer science last term, but I still absolutely adore octopuses (I have a plush octopus AND a plush Cthulhu! I sleep with the latter, while the former guards my computer) and hope to someday keep one as a pet.
In part because of this, I'm curious about your Cephus. Was he difficult to acquire (I've noticed that most pet stores around here don't keep them, but I may have more luck in Vancouver), and did you have much difficulty securing his tank? I've read some of the articles linked off here, and got the impression that they will escape from practically anything that isn't welded shut. I've also read that they're quite sensitive, so require very clean water and other specific environmental conditions. I haven't had fish since I was very young, so I suspect I'm best off getting a tank set up with other fish before I try to introduce anything with tentacles... but I would greatly appreciate tips from someone who's already had one as a pet.
Now, on the topic of the article, it actually doesn't surprise me that they'd walk like that. The mimic octopus in particular has been known to swim or otherwise move in unusual ways to imitate sea snakes, flounders, lionfish, and other sea creatures. I am, however, curious about whether they can be taught new camoflage and mimcry techniques (and if so, how much can they learn?). If studies have already been done on this, feel free to send me the links... otherwise, this is a hint to all you marine biologists out there looking for a research topic
:) -
Re:There is an issue here
Self- : [...] 2 a : to, with, for, or toward oneself or itself [...]
This is from http://www.m-w.com/cgi-bin/dictionary?va=self-plag iarism
Then they go on to list self-plagiarism as a word where you can draw the meaning yourself.
Now this univerisity defines self-plagiarism differently. In this case they refer to using material for which you have already received credit. So in this case lifting a paragraph from you're own website should be fine. My point is however that self-plagiarism is an idea that clearly does exist in English. -
Re:Broken link, java jab
evanbd:
I did a parallel implementation of an Amazons solver last summer. Drop me an e-mail if you want to chit chat about Amazons. -
Re:Speculation bubbles are not modern inventionsYou are so right, but there's one thought that I would add.
Just like the tulip mania or the South Sea Bubble or all the other bubbles since, once all the attention is on the stock rather than the intrinsic value of the product or service, then winning or losing depends on timing the market. (Or on having insider information.)
One thing that I think made the Dotcom Bubble a different twist was that it coincided with the rise of daytrading, the ubiquitous information age, and the age of easy credit card debt, so it was even easier for the people who have only the foggiest notion of evaluating and forecasting a stock's value to get into the market.
Certainly during the previous bubbles, lower-income people could still get in on the speculation, but there were several new forces converging to add to its capacity to reach investors.
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overfishingHistorically, improvements in fishing efficiencies have gone hand-in-hand with fisheries depletion. Better methods just kill more fish. It is difficult to be sanguine about technological improvements; policy changes are more promising.
The simple summary of recent fisheries history is that we are destroying stock after stock, around the world. For more on this, I recommend a Nature paper by my colleague Ransom Myers, entitled "Rapid worldwide depletion of predatory fish communities" [Nature 2003, vol 423: p280-283]. The paper is somewhat technical, but even if your Statistics are a bit rusty, check out Figure 2, which shows a world map of depletion. To give you a gist (and a chill up your spine), here's a quote from the paper: "Industrialized fisheries typically reduced community biomass by 80% within 15 years of exploitation."
If you don't have an online subscription to Nature.com, you can find the paper and related papers at Myers' website http://fish.dal.ca/~myers
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Health Informatics
Considering your medical background and interest in comptuer science, you may find health informatics to be of interest. You will be able to leverage all of your experience as a physician while breaking in to the field of computer science.
I work closely with the Departments of Health Informatics at Dalhousie University and University of Victoria and have met many of the other people in the field in Canada. They are a good mix of doctors, nurses and computer scientists and are doing some very interesting and releveant work.
You can find more information at http://www.hiww.org/ and by searching for Health Informatics on Google. -
medical informatics
First off I should mention that this is nothing more than a plug. Dalhousie university (Halifax, Nova Scotia, Canada) has just started a graduate program in Medical informatics. Medical informatics is basically the science of using mathematics and computers to data mine medical information for useful results. This is particularly relevant to this situation since the ideal candidates for this program are people with a medical background. People who can look at the data and form some sort of understanding of what it means in the real world. I know at the moment Dalhousie is the only Canadian school to offer such a program though I do believe there are a few American schools offering similar programs. Beyond that I don't know who else offers such a program.
It is also worth noting that Dalhousie Comp sci has just aquired Jon Borwein who is one of the worlds formost experts in experimental mathematics and just happens to have a history with several of the developers of the Medical informatics progam. It is unclear if he will be involved with the program but he will certainly be teaching courses at Dal. Probably worth looking into.