IIRC, the specific heat of water is around 4 while most metals are around 1. This means it takes 4x the amount of heat energy to raise water by 1 degree than to raise a similar metal by 1 degree.
Correct, but that is by weight. With a CPU, you want as much heat-absorbing capacity on as little space as possible, so it makes more sense to calculate the heat capacity per unit volume, which is the heat capacity times the density. The density of most metals is between 3 and 10 times more than that of water, so there you have your factor 4 back. Plus the advantage of a much better heat conductivity.
I actually think the source is formatted as such to make it hard to read.
It's to save bandwidth. Pretty formatted HTML and javascript takes more bytes and that makes a difference with the number of pages that Google is serving.
The normal way to clean a lens is with a foam swab and denatured alcohol.
Be careful. This works well for glass optics, but in cd players and such, the lenses are plastic, which can be attacked by solvents or change optical properties by absorbing them. It is safer to use isopropyl alcohol.
OVERWRITTEN TRACK ON A HARD DISK
(...) Acquisition time was about five minutes. Track width and skew, transition irregularities, and the difference between erased and virgin areas are visible. 25 micrometer scan.
That is five minutes of acquisition time for around one byte of information. I actually thought it would be a few bytes per second, but it's even worse than that: five minutes per byte! That'd only be useful if you know where to look within many GBs of data. Before you've found c:/Users and Settings/Cyberspook/projects/classified/secret.doc you probably have to recover (optimistically) 10 kB of directory data (i.e. 5 weeks of scanning), after which a 100 kB word document will take another year. Based on this I don't see a reason to worry very much.
Create an DNS RBL, something like compromized.rbl.yourdomain.net?
Well, that's technically hard on a shared host and it's not that many IPs. I was more wondering whether there are RBLs that I can submit these IPs to, or whether I can automatically inform the affected ISPs.
Just think about it: even if they pull out the platter and put it under an atomic force microscopy with a magnetic sensing tip, and really can identify a bit with 90% probability even after overwriting... if you need a byte, you are down to 50%,
AFAIK, data recovery normally deals with restoring data from drives with mechanical or electronic defects. Or with recovering deleted (but not overwritten) data, like the undelete tools in the DOS era.
Set up a honeypot on your website if you have one. I noticed that people were requesting/cgi-bin/formmail.pl about once a day, so I wrote a cgi-script that logged these requests. All the requests were probes that tried to see whether it would forward mails to any address. So I pasted the mail text into an email to this address: wnacyiplay@aol.com so that the spammer believed that it was a working gateway.
It's 10 days later now. The honeypot has absorbed 185 mails addressed to a total of 28,000 recipients. It feels good to know that I have prevented 28 thousand spam mails from being sent. You'd think that the spammer had noticed by now that the mails never arrive, but no...
As a side effect, the honeypot also generates IP addresses of compromised computers all over the world. I'm not sure what to do with those, though.
Have you ever been working on a paper at the last minute, say the night before a conference,
Sure, time pressure is the best thing to get me working. The biggest problem is not grammar and spelling, but being focused during an oral presentation after a night without sleep.:) Anyway, my personal experience is that I very rarely make spelling errors. For every error that I would catch, I have to go through 100s of false positives. Hence, for me a spell checker is a waste of time. (Of course, Emacs's spell-checker interface not being very user-friendly doesn't help either) Your mileage my vary. However, I've proofread enough manuscripts written by (apparently) dyslectic people which had been approved by Word's spell checker to make me believe that a spell checker gives you mostly a false sense of security.
Look up my publications (see homepage) and see for yourself. They are all written without spell checkers. When I type, I'm usually looking at the screen and I have a fairly good eye for spotting erroneous letter combinations.
It goes a bit far to require a software company to design software
that can do a full grammatical analysis of phrases. That is more
something for a long-term academic research project. Take for example
articles. If you've ever cooperated with someone with a background in
Asiatic or Slavic languages, you start to realize how hard that
is. The ground rule is: always put "a" or "the" in front of a singular
noun. Article placement (note: without article) is hard. The
article placement, or the lack thereof, in the previous sentence, was
correct. Why only "the" in the second phrase? How would you let a
wordprocessor feel the difference? Most of the grammatical errors in
the shown examples are about those articles.
I'd rather have a program that points out the typical mistakes that
occur when you cut and paste around, i.e. phrases without a verb, or
with too many verbs, than one that is giving false alarms all the
time. A grammar checker cannot fix a bad writer. Neither a spell checker, for that matter. (Do you write "advise" or "advice"?)
Personally, I don't use grammar checkers (not available for Emacs
AFAIK anyway), and a spell checker only if I doubt about a particular
word. There are way too many words in the kind of things that I write
that make the spell checker freak out.
BTW, I probably made a mistake or two in this posting. My excuse is
that I ain't no native speaker.:)
People NEVER verify the card holders name to the ID these days
But ask yourself: why is that? The card issuer could easily require
shopkeepers to have the customer enter a PIN or show an ID. To prove
that the ID was checked, the shopkeeper has to write down the
registration number of the ID. This is how it works in Sweden. In
Netherlands, people rarely use credit cards, but rather debit cards
which can only be used with a PIN. A fraudster would either need to
see the card owner enter the PIN and steal the card, or install a fake
cardreader somewhere. The result: card fraud is very rare.
(As an aside, to obtain a photo ID in Sweden, you need to show up
at a bank or post office with a witness, and both of you need to show
a document that is sent to your registered home address, plus other
proof about your identities. It's pretty hard to steal someone's
identity that way)
Anyway, the problem is that if one CC company is the first to
require merchants to take precautions, every customer will hate them
for the extra fuss. The customer won't feel in his wallet that the CC
company only takes 0.5% (administrative fees) instead of 5% (covering
fraud) from every transactions, because it is the shopkeeper who
has to bear those fees.
get an electronic switch, set it as alarm clock switching a lamp shining at your face on at a given time
When I moved to Sweden, I lived for a while in an apartment with a huge (1 square meter) window in the ceiling. Without blinds or anything. It was late spring and nice weather, so I was actually wide awake at 6 or 7 every morning. I almost thought that I had become a morning person.
Too bad. I soon learned to pull the blankets over my head while sleeping.
The Swedish Chef on the Muppet Show doesn't speak any Swedish. At all.
I think it sounds more like Danish, but my Danish friends think he's from Norway. Any Norwegians here to comment on this?
Re:The myth is dead! Long live the myth!
on
The Solar Death Ray
·
· Score: 2, Insightful
Mythbusters almost did a great job, but forgot one important thing. A shield is concave, which has the amazing property of focusing light. The Mytbusters used flat mirrors.
If you want to burn a ship that's several hundred meters away with a reflection from the sun, it doesn't matter very much whether the mirrors have exactly the right curvature or are flat. Even a perfect curved mirror would create a perfect image of the sun the diameter of which depends on the distance between the mirror and the image. At 200 m, you could focus the sun to a 2 m diameter disc. As long as the individual reflectors are significantly smaller than 2 m, it doesn't make much of a difference.
Of course it makes sense that it is healthy to stay away from potential sources of diseases. I just find it so strange that rational knowledge about the actual disease-causing potential doesn't win from gut feelings. I also don't understand how these instincts can be genetically determined for things that are related to disease in such a artificial (chemical colors rather than a putrid smell).
Anyway, about this disgust-test, it seems that I'm not that sensitive. No problems with bugs, slime, and dirty towels (hey, I've lived as a bachelor during the past 12 years, I'm used to a few things:). I only feel yucky about skin diseases and open wounds, and the type of effects in horror movies.
First of all, about 60% of/. stories are 2-day-old posts on either Gizmodo, Engadget, Lifehacker, or Hack-A-Day. I doubt/. editors even realize this, because they obviously don't get "out" very much.
Well, if you're only interested in the latest gadgets on the market, then maybe slashdot is not the right place for you.
I don't care that much about the freshness of the news, especially not about gadgets. What I do care about is that the stories provoke interesting discussions. There is a reason that people don't RTFAs: the articles themselves often contain very little information anyway.
Postings on slashdot tend to be intelligent and well-written. Browse at +3 if you don't believe me. Some people here complain that the/. crowd can't spell because they write loose instead of lose somewhere in a long post. Get some perspective! Here someone with an IQ of 145 tells someone with an IQ of 125 that he's stupid. Compare it to any phpBB forum on the net.
When I post an issue in Bugzilla.mozilla.org, the system gives me a list of potential duplicates. How can't that be done for slashdot?
Maybe the problem is in the time lag between acceptance of a story submission and the actual publication. I don't know the details of the editorial process, but I imagine that several different editors go through 300 submissions every day. These submissions are then given a priority (publish today or during the next week) and pipelined. If the dupe is sitting in the pipeline before the original has made the frontpage, it is technically not yet a dupe. You could imagine a good dupechecker that also checks the pipeline, but it's a bit more work than "just search for old stories."
By the way, as a subscriber I can see the stories half an hour before they go live, with an invitation to report it as a dupe. It happens every now and then that the story is a dupe and disappears without the non-subscribers ever seeing it. The system of course doesn't work if the on-duty editor is having a lunch break or something.
Er, well, not exactly. grep, extended (egrep) and fixed (fgrep) allow for different feature/speed tradeoffs, but they are consistent in their use of regular expressions. Where you will find differences is between the regex syntax of vi, perl, sed, grep, etc.
What I don't like about the grep/egrep-style REs is that it is internally inconsistent. Some characters are taken to be literal if you place a backslash in front of them, other ones become active with a backslash. Perl is much simpler: a backslash always turns a non-letter into a literal, whether it was literal or not. I'm always fighting with the conventions in grep and emacs. Argh. Maybe I should find a perl-based grep and a perl-re emacs module or something.
I can't reproduce this with various combinations of LC_CTYPE and LC_COLLATE (my default is ctype=en_US, collate=C). Anyway, the fact that the result depends on system-wide settings makes the error even worse.
The primary moving factor is that as you increase CO2 plants absorb more, and grow more, studies have shown that concentrations up to twice current amounts are wildly beneficial to plant life.
Assuming that that is correct (I cannot judge that), plantlife in most types of environment does not store carbon. Rather, there is an equibrium between young trees that are storing carbon and old dying trees that release the carbon as they are broken down. Converting plains into forest gives you a one-time carbon sink. Coal and oil are the result of vegetation in a specific type of environment where the dead plant parts could not be broken down due to a lack of oxygen.
no one is saying that CO2 alone will increase warming, but rather that it will do a small increase which will induce more atmospheric water vapor, which will then create the serious warming. And all of these models use only positive reinforcement, and ignore any counterbalancing effects (Clouds shade and thus reduce warming, increases water vapor will also increase cloud cover).
I agree (i.e., read before) that a large part of the atmospheric greenhouse effect is due to the interaction between CO2, temperature, and water vapour. But I am skeptical about your blanket statement about the current state of the art in climate modeling. You are basically stating that all climate researchers ignore a very obvious process in their supercomputer models. Do you have a reference for that? Or do you mean that it is disputed how exactly this effect should be incorporated into the models?
Anyway, as I understand, the cloud cover effect is yet hard to model. That would be the a main reason why the IPCC predictions have a large spread in their predictions---what was it? 2 to 7 degrees C over the next 100 years? The thing is, whatever reasonable assumptions regarding the cloud effect the climate researchers put into their models, it always leads to a global temperature increase. The dispute is about whether it is a "significant raise" or a "huge raise".
In the ascii code table, the uppercase letters A-Z are followed by a number of special symbols, then followed by the lowercase letters a-z. The pattern [A-z] matches all characters that are between A and z in the ascii table, including those symbols, which is usually not what you want.
Well goody, since the US is a net carbon sink we don't have anything to worry about here.
Okey, the Kyoto protocol is about the CO2 balance, but of course only the part that human behaviour can affect. It is a human decision to burn oil and coal, or to plant new trees. The natural part of the carbon cycle which was already there before mankind started burning dinosaurs doesn't count for the political decisions that have to be made now.
But what about Methane which is a much more potent greenhouse gas?
Methane contributes strongly to the greenhouse effect; but the difference with CO2 is that it has a residence time of 12 years. So once you figure out how to stop cows from burping, its greenhouse contribution will disappear in a couple of years.
On the other hand, CO2 has a residence time of around 100 years. That means that you have to work much harder to lower its greenhouse contribution. Instead of undoing the last 12 years of production as with methane, you have to compensate for the CO2 production in the last 100 years!
Require drug companies to open up that amount of research was was carried out using public funds.
You can look at it from the other side. You want to do academic reseach on farmaceuticals, but the state provides only half the funding you need. Then the farmaceutical company comes by and says: look, I can pay for the other half, but the deal is that you wait a year with publication so that we can file patents. Take it or leave.
It's an other thing if the pharmaceutical company blocks publication because the scientific results say that their product doesn't cure the disease it was meant to cure.
one of the biggest sources of pollution globally is Southeast Asian cooking fires, something Kyoto would have ignored.
I don't know the details about this issue, but Kyoto is about CO2 budgets, not about air pollution. Burning wood for cooking may produce soot, but it doesn't produce extra CO2 as long as new trees take the place of the once that are burnt.
Slashdot Mirror
Correct, but that is by weight. With a CPU, you want as much heat-absorbing capacity on as little space as possible, so it makes more sense to calculate the heat capacity per unit volume, which is the heat capacity times the density. The density of most metals is between 3 and 10 times more than that of water, so there you have your factor 4 back. Plus the advantage of a much better heat conductivity.
It's to save bandwidth. Pretty formatted HTML and javascript takes more bytes and that makes a difference with the number of pages that Google is serving.
Be careful. This works well for glass optics, but in cd players and such, the lenses are plastic, which can be attacked by solvents or change optical properties by absorbing them. It is safer to use isopropyl alcohol.
That was an interesting link. However, I quote:
That is five minutes of acquisition time for around one byte of information. I actually thought it would be a few bytes per second, but it's even worse than that: five minutes per byte! That'd only be useful if you know where to look within many GBs of data. Before you've found c:/Users and Settings/Cyberspook/projects/classified/secret.doWell, that's technically hard on a shared host and it's not that many IPs. I was more wondering whether there are RBLs that I can submit these IPs to, or whether I can automatically inform the affected ISPs.
Finally someone in this discussion who gets it. Apart from that, the speed of an AFM/MFM microscope would be a couple of bytes per second. Good luck recovering a 40 GB harddisk with that. Nobody has ever demonstrated a successful recovery of overwritten data.
AFAIK, data recovery normally deals with restoring data from drives with mechanical or electronic defects. Or with recovering deleted (but not overwritten) data, like the undelete tools in the DOS era.
Set up a honeypot on your website if you have one. I noticed that people were requesting /cgi-bin/formmail.pl about once a day, so I wrote a cgi-script that logged these requests. All the requests were probes that tried to see whether it would forward mails to any address. So I pasted the mail text into an email to this address: wnacyiplay@aol.com so that the spammer believed that it was a working gateway.
It's 10 days later now. The honeypot has absorbed 185 mails addressed to a total of 28,000 recipients. It feels good to know that I have prevented 28 thousand spam mails from being sent. You'd think that the spammer had noticed by now that the mails never arrive, but no...
As a side effect, the honeypot also generates IP addresses of compromised computers all over the world. I'm not sure what to do with those, though.
Sure, time pressure is the best thing to get me working. The biggest problem is not grammar and spelling, but being focused during an oral presentation after a night without sleep. :) Anyway, my personal experience is that I very rarely make spelling errors. For every error that I would catch, I have to go through 100s of false positives. Hence, for me a spell checker is a waste of time. (Of course, Emacs's spell-checker interface not being very user-friendly doesn't help either) Your mileage my vary. However, I've proofread enough manuscripts written by (apparently) dyslectic people which had been approved by Word's spell checker to make me believe that a spell checker gives you mostly a false sense of security.
Look up my publications (see homepage) and see for yourself. They are all written without spell checkers. When I type, I'm usually looking at the screen and I have a fairly good eye for spotting erroneous letter combinations.
I'd rather have a program that points out the typical mistakes that occur when you cut and paste around, i.e. phrases without a verb, or with too many verbs, than one that is giving false alarms all the time. A grammar checker cannot fix a bad writer. Neither a spell checker, for that matter. (Do you write "advise" or "advice"?)
Personally, I don't use grammar checkers (not available for Emacs AFAIK anyway), and a spell checker only if I doubt about a particular word. There are way too many words in the kind of things that I write that make the spell checker freak out.
BTW, I probably made a mistake or two in this posting. My excuse is that I ain't no native speaker. :)
But ask yourself: why is that? The card issuer could easily require shopkeepers to have the customer enter a PIN or show an ID. To prove that the ID was checked, the shopkeeper has to write down the registration number of the ID. This is how it works in Sweden. In Netherlands, people rarely use credit cards, but rather debit cards which can only be used with a PIN. A fraudster would either need to see the card owner enter the PIN and steal the card, or install a fake cardreader somewhere. The result: card fraud is very rare.
(As an aside, to obtain a photo ID in Sweden, you need to show up at a bank or post office with a witness, and both of you need to show a document that is sent to your registered home address, plus other proof about your identities. It's pretty hard to steal someone's identity that way)
Anyway, the problem is that if one CC company is the first to require merchants to take precautions, every customer will hate them for the extra fuss. The customer won't feel in his wallet that the CC company only takes 0.5% (administrative fees) instead of 5% (covering fraud) from every transactions, because it is the shopkeeper who has to bear those fees.
When I moved to Sweden, I lived for a while in an apartment with a huge (1 square meter) window in the ceiling. Without blinds or anything. It was late spring and nice weather, so I was actually wide awake at 6 or 7 every morning. I almost thought that I had become a morning person.
Too bad. I soon learned to pull the blankets over my head while sleeping.
I think it sounds more like Danish, but my Danish friends think he's from Norway. Any Norwegians here to comment on this?
If you want to burn a ship that's several hundred meters away with a reflection from the sun, it doesn't matter very much whether the mirrors have exactly the right curvature or are flat. Even a perfect curved mirror would create a perfect image of the sun the diameter of which depends on the distance between the mirror and the image. At 200 m, you could focus the sun to a 2 m diameter disc. As long as the individual reflectors are significantly smaller than 2 m, it doesn't make much of a difference.
Anyway, about this disgust-test, it seems that I'm not that sensitive. No problems with bugs, slime, and dirty towels (hey, I've lived as a bachelor during the past 12 years, I'm used to a few things :). I only feel yucky about skin diseases and open wounds, and the type of effects in horror movies.
Well, if you're only interested in the latest gadgets on the market, then maybe slashdot is not the right place for you.
I don't care that much about the freshness of the news, especially not about gadgets. What I do care about is that the stories provoke interesting discussions. There is a reason that people don't RTFAs: the articles themselves often contain very little information anyway.
Postings on slashdot tend to be intelligent and well-written. Browse at +3 if you don't believe me. Some people here complain that the /. crowd can't spell because they write loose instead of lose somewhere in a long post. Get some perspective! Here someone with an IQ of 145 tells someone with an IQ of 125 that he's stupid. Compare it to any phpBB forum on the net.
Maybe the problem is in the time lag between acceptance of a story submission and the actual publication. I don't know the details of the editorial process, but I imagine that several different editors go through 300 submissions every day. These submissions are then given a priority (publish today or during the next week) and pipelined. If the dupe is sitting in the pipeline before the original has made the frontpage, it is technically not yet a dupe. You could imagine a good dupechecker that also checks the pipeline, but it's a bit more work than "just search for old stories."
By the way, as a subscriber I can see the stories half an hour before they go live, with an invitation to report it as a dupe. It happens every now and then that the story is a dupe and disappears without the non-subscribers ever seeing it. The system of course doesn't work if the on-duty editor is having a lunch break or something.
What I don't like about the grep/egrep-style REs is that it is internally inconsistent. Some characters are taken to be literal if you place a backslash in front of them, other ones become active with a backslash. Perl is much simpler: a backslash always turns a non-letter into a literal, whether it was literal or not. I'm always fighting with the conventions in grep and emacs. Argh. Maybe I should find a perl-based grep and a perl-re emacs module or something.
I can't reproduce this with various combinations of LC_CTYPE and LC_COLLATE (my default is ctype=en_US, collate=C). Anyway, the fact that the result depends on system-wide settings makes the error even worse.
Assuming that that is correct (I cannot judge that), plantlife in most types of environment does not store carbon. Rather, there is an equibrium between young trees that are storing carbon and old dying trees that release the carbon as they are broken down. Converting plains into forest gives you a one-time carbon sink. Coal and oil are the result of vegetation in a specific type of environment where the dead plant parts could not be broken down due to a lack of oxygen.
no one is saying that CO2 alone will increase warming, but rather that it will do a small increase which will induce more atmospheric water vapor, which will then create the serious warming. And all of these models use only positive reinforcement, and ignore any counterbalancing effects (Clouds shade and thus reduce warming, increases water vapor will also increase cloud cover).
I agree (i.e., read before) that a large part of the atmospheric greenhouse effect is due to the interaction between CO2, temperature, and water vapour. But I am skeptical about your blanket statement about the current state of the art in climate modeling. You are basically stating that all climate researchers ignore a very obvious process in their supercomputer models. Do you have a reference for that? Or do you mean that it is disputed how exactly this effect should be incorporated into the models?
Anyway, as I understand, the cloud cover effect is yet hard to model. That would be the a main reason why the IPCC predictions have a large spread in their predictions---what was it? 2 to 7 degrees C over the next 100 years? The thing is, whatever reasonable assumptions regarding the cloud effect the climate researchers put into their models, it always leads to a global temperature increase. The dispute is about whether it is a "significant raise" or a "huge raise".
Yes, but here on /. we're supposed to start a big flamewar everytime something with "climate change" in the title comes up. :)
Okey, the Kyoto protocol is about the CO2 balance, but of course only the part that human behaviour can affect. It is a human decision to burn oil and coal, or to plant new trees. The natural part of the carbon cycle which was already there before mankind started burning dinosaurs doesn't count for the political decisions that have to be made now.
But what about Methane which is a much more potent greenhouse gas?
Methane contributes strongly to the greenhouse effect; but the difference with CO2 is that it has a residence time of 12 years. So once you figure out how to stop cows from burping, its greenhouse contribution will disappear in a couple of years.
On the other hand, CO2 has a residence time of around 100 years. That means that you have to work much harder to lower its greenhouse contribution. Instead of undoing the last 12 years of production as with methane, you have to compensate for the CO2 production in the last 100 years!
Reference: What are greenhouse gases? (I googled for "residence time co2 climate" )
You can look at it from the other side. You want to do academic reseach on farmaceuticals, but the state provides only half the funding you need. Then the farmaceutical company comes by and says: look, I can pay for the other half, but the deal is that you wait a year with publication so that we can file patents. Take it or leave.
It's an other thing if the pharmaceutical company blocks publication because the scientific results say that their product doesn't cure the disease it was meant to cure.
I don't know the details about this issue, but Kyoto is about CO2 budgets, not about air pollution. Burning wood for cooking may produce soot, but it doesn't produce extra CO2 as long as new trees take the place of the once that are burnt.