Since all mirrors with finite apertures suffer from diffraction blurring, we can neglect the blur due to spherical aberration as long as it is less than the diffraction blur.
Which it is when the f-ratio is f10 or greater. That was my only point. I've built an F11 Newtonian refractor with a spherical mirror and it was diffraction-limited. On the other hand, there is no such thing as an f4 diffraction-limited spherical mirror.
We can still say with certainty that paraxial focus is at half the radius of curvature of the mirror
Agreed. My point was that, when one can identify several foci, it's not technically correct to just pick one of them and call that "the focal length". Your point about that being proper when the f-ratio is such that the mirror is diffraction-limited is correct (and was the reason for my Newtonian reflector example).
By the way, I'm impressed with you knowledge of optics.
Just remember - a new record will sound far, far better then a CD.
What utter, absolute, audiophile-elitist bull.
I've got a Linn turntable, arm, and cartridge (sold for about $1k when new). It's feeding a PS Audio phono preamp with switch-selectable input capacitance and impedence. That's a pretty decent vinyl playing setup and I can tell you that, even when listening to something like Mobile Fidelity Sound Lab recordings, that LPs sound significantly inferior to CDs.
LPs, even when played through the finest equipment, have distortion that's more than an order of magnitude worse than CDs. It can be measured and shown. You get overshoot both from the mastering and from the playback caused by the fact that the styli have mass. The turntable acts as a microphone, picking up vibration from the air and the floor, feeding it back through the cartridge as well as feeding vibration from its own motor back through (you probably call that "warmth"). The noise floor of vinyl is horrendous with "silent" lead-in grooves being anything but silent. The dynamic range of vinyl, due to the noise floor combined with physical limitations of phono cartridges, is extremely limited compared to CD.
If you prefer the sound of LP to CD, then it is because you find the distortion and noise of LPs appealing. Period.
For your information, the focal length of a spherical mirror is half the radius of curvature.
I think that you should say "approximately", since a spherical mirror never really truly comes into focus due to spherical aberration. That's why Newtonian astronomical telescopes use parabolic mirrors for anything faster than f10.
Cutie Pi 3.1415926535897932384626433832795028841972....
If you are going to show Pi with "..." to indicate that it keeps going, the last digit should be a one, not a two. The two you are showing is because the version you have is rounded at the 40th decimal place. The actual 40th place is a one and the 41st is a six (...41971693993...).
Want to know something really scary? I did that from memory.
It's an introductory class. Most people who go to MIT have no prior experience with circuits as they don't teach the subject in high school.
That's pathetic! I was building and modifying electronic circuits when I was in jr. high school. Anyone who has so little interest in electronics that they never even built something before reaching college has no business becoming an EE.
Could multiple companies that make dive computers be using the same algorthym?
Algorithm, yes. Actual code, sometimes. The way that one can tell is that the "shared" systems have similar, or identical displays. Remember, these are not dot-matrix displays. They are custom LCDs with fixed digit and character placement and size.
There are also operational similarities having to do with how one recalls dives, changes displayed info, etc. The documentation on "shared" dive computers is often the same.
Really, they are like cars: You can tell looking at a Pontiac Firebird and a Chevy Camaro that it's basically the same car.
They've all done the sums and if it's more cost effective to manufacture (slightly) defective parts with a reduced warranty, well, they're right onto it.
Maybe they have accountants, engineers, and marketing staff working for them and, thus, have the ability to determine what the optimum mix of warranty and sales price is. A five year warranty does not mean that the company offering it expects zero failures in five years. It means that they expect to be able to sell the drives and provide warranty service for five years and still make a profit.
All I want is a drive bigger than 40GB that'll actually *last* 5 years. Is that so hard? Apparently yes. I've got 80MB drives that are thirteen years old and still get run 8hrs a day.
So all you want is a drive that is the same physical size or smaller, holds at least 500 times the amount of data, spins 50% faster, transfers data an order of magnitude faster, costs about 1/3 as much, and lasts 5 years. Yeah, that sounds reasonable.
Tell you what: I'll sell you a 70GB drive for $450 and warranty it against failures (other than those caused by abuse) for five years. Oh, wait, that's how they offer the five year warranty on SCSI already, isn't it?
Looks to me like seagate believes they're better drives.
Please tell me that you don't actually intend to pass that off as a logical conclusion.
Seagate 80GB IDE drive: $99.99 Seagate 73.4GB SCSI drive: $459.99
How the hell is Seagate supposed to provide a five year warranty on a drive that's being sold to consumers for $100? It's pretty easy to see that there is enough profit margin to cover a 5 year warranty for a $460 73GB SCSI drive.
Samsung still has 3 year warranties on their ide drives. Only one I'l buy from now.
Good for you. You can get a slower, less reliable drive with a longer warranty (I have experience on a project that used Samsung drives in over 3,000 systems). And when that $99 drive dies, you can stop working on your computer, send it back, wait for a replacement, put that in, install the OS and try to reconstruct your data. Good luck.
Hyundai and Kia cars have 10 year/100,000 mile powertrain warrantees. I guess you think that Hyundai and Kia cars are the most reliable in the world.
Also we shouldn't begrudge poorer nations our help.
I agree with this totally. In fact, I am sickened by the fact that we can find the money to wage war in Iraq but can't find the money to save millions of people who are starving to death in Ethiopia.
But we should begrudge those nations our jobs when we have the highest unemployment in decades. At times like this, the U.S. government, and, yes, U.S. corporations, should be concerned with the well-being of U.S. citizens.
Some guy being paid $2.80 per day in China to build Sears Crafsman drill presses is not going to be buying a Sears Craftsman drill press anytime soon. I think that we are already seeing the effects of U.S. businesses poisoning the well by outsourcing U.S. jobs. Consumers have less money to spend and those who do have it are hesitant to spend, not knowing if they will find themselves victims of outsourcing in the near future.
I would think that the US would want Asia to develop more so they could become greater trading partners.
I can't speak for the U.S., but what I have seen as a result of the development of Asia is outsourcing of U.S. jobs. Everything from tech support to engineering to manufacturing is being outsourced. I'm sure that makes some U.S. CEOs very happy, but it does nothing for the millions of Americans who, as a result, are out of work. Since China, for example, can be largely self-sufficient, the opportunities for export to China are limited and will remain that way until wages more or less equalize between the U.S. and China. While that is somewhat of an oversimplification in that it does not take into account worker efficiency or the costs to transport goods, it's basically true. Chinese citizens won't buy an American-made widget that when the Chinese-made widget is a fraction of the cost due to lower Chinese production costs. This cost differential will lead to an ever greater trade imbalance, with the U.S. importing Chinese goods and exporting U.S. jobs.
I can hardly get upset about China's inability to make do with the IP address space we so graciously provided them. Development of the Internet and its basic protocols (IP, TCP/IP, UDP, ettc.) was done by the U.S. at U.S. taxpayer expense. Yeah, I know that others later created applications that used those protocols (like HTTP), but the U.S. invented everything from Ethernet to the IP protocol, so we are entitled to as great a percentage of IPV4 as we want.
The above was not a troll. It was what I truly believe. Don't like it? Then debate like a man instead of trying to hide what I say with negative moderation.
I can hardly get upset about China's inability to make do with the IP address space we so graciously provided them. Development of the Internet and its basic protocols (IP, TCP/IP, UDP, ettc.) was done by the U.S. at U.S. taxpayer expense. Yeah, I know that others later created applications that used those protocols (like HTTP), but the U.S. invented everything from Ethernet to the IP protocol, so we are entitled to as great a percentage of IPV4 as we want.
I'm just saying, GWB got a larger percent of the popular vote in 200 than Clinton did in 1992. If GWB doesn't have a mandate, clinton didn't either.
Fine. Clinton didn't have a mandate. Neither does Bush. The economy was great under Clinton. It sucks under Bush. Who the f*** cares about a "mandate?" Most people are more concerned about having a job and not losing their life's savings.
And when did this recession start? During the Clinton administration! It has leveled off and started a slow climb up.
Bull. The stock markets keep falling. Unemployment keeps rising. Economists are now in fear of deflation. Bush's plan is to do deficit spending so recklessly that we pay interest on the debt he accrues for years to come -- just as happened under Reagan and Dubya's dad, when the national debt skyrocketed. When Clinton took office, 25% of every federal tax dollar taken in was spent paying interest on the debt.
I guess everyone can't spend anymore, because most americans have racked up a fortune in credit card debt in the '90's.
Coming from a borrow-and-spend Republican, you have a lot of nerve. Bush is burying this country in debt by cutting taxes while massively increasing federal spending, racking up the largest ever deficit. When the President can't see a disadvantage to massive borrowing, how can you fault the public for doing the same thing?
Unemployed people aren't spending money because they don't have income. It's not "credit card debt." It's unemployment. It's a lack of consumer confidence. And that's the fault of the current President, not the one that left office in 2000.
Clinton inherited a recession from George Bush and Clinton's economic policies got us out of that debt and lead us to the most economically productive 8 years in the history of this country. Bush has been in office since 2001 and the economy is still in a death spiral.
Everybody has the hangover right now from the crazy uncontrolled growth in the '90's, and right now we are slowly recovering from Clinton's recession.
I guess we won't have any of that "uncontrolled growth" to worry about as long as Dubya's at the helm. Nope. I've seen no sign of it.
Well, I was talking about 1996 and since I'm the only one that named numbers, that's the year we will talk about.
Clinton still didn't get 50% in 1996 either, but he didn't get near that in 1992....
And what would GWB have gotten if there had been a strong third-party candidate that got 19% of the vote? You are comparing what was, essentially, three-way elections to a two-way election. What kind of way is that to judge a candidate's popularity?
Yeah, but Clinton didn't get over 50% of the popular vote though! So did he really have a mandate.
In 1992 and 1996, when Clinton won the Presidential elections, Perot was a strong candidate, taking 19% of the vote in 1992 and 8% of the vote in 1996. The strongest candidate compared to Gore and Bush was Nader, who only garnered a mere 2.74% of the vote of the popular vote in 2000. Had Perot not run, Clinton would have been well over the 50% mark (since he hit 49% in 1996 even with Perot in the race).
GWB actually had a larger % of the popular vote than Clinton did....
Says who? Rush Limbaugh? G. Gordon Liddy? Some other right-wing radio blowhard? Whoever said it, it's a load of crap. In 1996, Clinton got 49% of the popular vote while, in 2000, GWB only got 47.37% of the vote (Gore got 48.38%).
And aren't we doing well since Bush took office? We're in a recession. Unemployment is higher than it has been in years. Wages are down. Jobs are being exported overseas. The deficit spending is the highest it has ever been. And Bush and the Republican Congress just pushed through a tax windfall for the rich. We've ruined our credibility by claiming Iraq had "Weapons of Mass Destruction" and then, after invading the country, being unable to find any of the supposed weapons. I'll be so happy when GWB is booted out of office and replaced with someone who understands that deficit spending is crippling our economy and that we don't have a right to impose our will on the rest of the world.
I thought that the PADI tables are not the same as USN tables.
They are not the same as the Navy tables, however, they were initially very close.
Another point is that the USN tables assume a younger and fitter diver. PADI has to use a tissue model for a much wider range of body types (for non divers here, the amount of nitrogen held by different types of tissue, i.e., muscle, fat, is variable).
Also true. Although earlier PADI tables were simply USN tables with more conservative times rather than being based on scientific research into nitrogen uptake of various tissue types.
However, that last bit you say about trying to dive with a buddy with a different computer is one of the best ideas.
So many diving couples make the mistake of getting matching dive computers when that is, in fact, the last thing that you want. The two divers profiled in the story both used the defective UWATEC dive computers. Had either of them had a different model, they would probably have recognized the problem before it was a life-threatening danger.
Like you, I also believe in backups. I have three ways to measure my depth: Computer, analog depth gauge, and Citizen watch with depth gauge. I time the dive using both the watch and the computer. I take waterproof dive tables with me in the pocket of my BC. And that's not even counting the duplication that I get when my buddy has her computer, watch, and depth gauge.
Diving gear is life-support equipment. I find it disgusting when dive shops peddle regulators, consoles, tanks, and BCs based on color coordination rather than on design, construction, and reliability.
Don't forget that, for years, the PADI dive tables were Navy Dive Tables. For a very good history of dive tables, click here. Dive tables are based on the same theories and technology as dive computers. The biggest difference is that they are more prone to human error than are dive computers.
It's great to say "plan your dive and dive your plan", but people are fallible. Your buddy may go a little deeper than he/she intended. You may, because of narcosis, get confused about the maximum time or depth. You or they might have problems that slightly delay your ascent. If you plan to go to 90 feet and you drop a video camera to the bottom at 110, unless you're Bill Gates, you're probably going to go get the camera and cut the dive short. So much for the plan. (I've been a diver for over fifteen years. I've seen everything from divers getting entangled in wrecks to outright equipment failures. Don't reply with some macho explanation of how you can foresee and prevent every error. You can't and if you believe that you can, then you need to stop diving until your ego and testosterone stop affecting your reasoning.)
My buddy and I each bought dive computers at the same time. I made it a point to choose dive computers from different manufacturers so that a sofware flaw in one would not put us at undue risk. We stick close together and always use the more conservative of the two computer readings. Had one of us had a UWATEC computer, we would have noticed the problem immediately when comparing the two computers.
I'd sure like to see this brain surgeon try and find out who's on my whitelist and forge their address.
That must be really handy when you are advertising something for sale, providing your e-mail address on a resumé that you post, or handing out business cards with your e-mail address on them. Blocking all e-mail not from whitelisted addresses is one way to make e-mail unusable.
I cannot help but notice that people are in a company for 15-20 years, but still do not find themselves in a position to make these decisions.
Yet they feel comfortable complaining about the decisions made by the ones who are in that position.
If management is "comfortable" criticizing the work of those people who have chosen a career in software engineering, why shouldn't software engineers criticize the work (i.e., decisions) of those who have chosen a career in management? Many software engineers are in that field because they enjoy the work. They don't aspire to be managers. Criticizing them because they have not become managers is invalid.
But who's waiting to take over for the COBOL programmers? No one now, no one coming soon, and no one in the forseeable future. That's the problem.
If COBOL programmers were paid as handsomely as executives and corporate attorneys, you would find plenty of people eager to learn COBOL.
This is not some big mystery. Why would someone in the IT field go that direction when COBOL programmers are paid more poorly, have less opportunity for advancement, and generally do less rewarding work? It's like paying teachers $20K per year and wondering why more people aren't getting teaching degrees.
Slashdot Mirror
Since all mirrors with finite apertures suffer from diffraction blurring, we can neglect the blur due to spherical aberration as long as it is less than the diffraction blur.
Which it is when the f-ratio is f10 or greater. That was my only point. I've built an F11 Newtonian refractor with a spherical mirror and it was diffraction-limited. On the other hand, there is no such thing as an f4 diffraction-limited spherical mirror.
We can still say with certainty that paraxial focus is at half the radius of curvature of the mirror
Agreed. My point was that, when one can identify several foci, it's not technically correct to just pick one of them and call that "the focal length".
Your point about that being proper when the f-ratio is such that the mirror is diffraction-limited is correct (and was the reason for my Newtonian reflector example).
By the way, I'm impressed with you knowledge of optics.
Just remember - a new record will sound far, far better then a CD.
What utter, absolute, audiophile-elitist bull.
I've got a Linn turntable, arm, and cartridge (sold for about $1k when new). It's feeding a PS Audio phono preamp with switch-selectable input capacitance and impedence. That's a pretty decent vinyl playing setup and I can tell you that, even when listening to something like Mobile Fidelity Sound Lab recordings, that LPs sound significantly inferior to CDs.
LPs, even when played through the finest equipment, have distortion that's more than an order of magnitude worse than CDs. It can be measured and shown. You get overshoot both from the mastering and from the playback caused by the fact that the styli have mass. The turntable acts as a microphone, picking up vibration from the air and the floor, feeding it back through the cartridge as well as feeding vibration from its own motor back through (you probably call that "warmth"). The noise floor of vinyl is horrendous with "silent" lead-in grooves being anything but silent. The dynamic range of vinyl, due to the noise floor combined with physical limitations of phono cartridges, is extremely limited compared to CD.
If you prefer the sound of LP to CD, then it is because you find the distortion and noise of LPs appealing. Period.
For your information, the focal length of a spherical mirror is half the radius of curvature.
I think that you should say "approximately", since a spherical mirror never really truly comes into focus due to spherical aberration. That's why Newtonian astronomical telescopes use parabolic mirrors for anything faster than f10.
Your sig:
Cutie Pi 3.1415926535897932384626433832795028841972....
If you are going to show Pi with "..." to indicate that it keeps going, the last digit should be a one, not a two. The two you are showing is because the version you have is rounded at the 40th decimal place. The actual 40th place is a one and the 41st is a six (...41971693993...).
Want to know something really scary? I did that from memory.
It's an introductory class. Most people who go to MIT have no prior experience with circuits as they don't teach the subject in high school.
That's pathetic! I was building and modifying electronic circuits when I was in jr. high school. Anyone who has so little interest in electronics that they never even built something before reaching college has no business becoming an EE.
Could multiple companies that make dive computers be using the same algorthym?
Algorithm, yes. Actual code, sometimes. The way that one can tell is that the "shared" systems have similar, or identical displays. Remember, these are not dot-matrix displays. They are custom LCDs with fixed digit and character placement and size.
There are also operational similarities having to do with how one recalls dives, changes displayed info, etc. The documentation on "shared" dive computers is often the same.
Really, they are like cars: You can tell looking at a Pontiac Firebird and a Chevy Camaro that it's basically the same car.
I always considered the moon landing an achievement for the entire human race.
So do I. "This is one small step for man... one giant leap for mankind."
They've all done the sums and if it's more cost effective to manufacture (slightly) defective parts with a reduced warranty, well, they're right onto it.
Maybe they have accountants, engineers, and marketing staff working for them and, thus, have the ability to determine what the optimum mix of warranty and sales price is. A five year warranty does not mean that the company offering it expects zero failures in five years. It means that they expect to be able to sell the drives and provide warranty service for five years and still make a profit.
All I want is a drive bigger than 40GB that'll actually *last* 5 years. Is that so hard? Apparently yes. I've got 80MB drives that are thirteen years old and still get run 8hrs a day.
So all you want is a drive that is the same physical size or smaller, holds at least 500 times the amount of data, spins 50% faster, transfers data an order of magnitude faster, costs about 1/3 as much, and lasts 5 years. Yeah, that sounds reasonable.
Tell you what: I'll sell you a 70GB drive for $450 and warranty it against failures (other than those caused by abuse) for five years. Oh, wait, that's how they offer the five year warranty on SCSI already, isn't it?
Warranty on seagate ide drive == 1 year
warranty on seagate scsi drive == 5 years.
Looks to me like seagate believes they're better drives.
Please tell me that you don't actually intend to pass that off as a logical conclusion.
Seagate 80GB IDE drive: $99.99
Seagate 73.4GB SCSI drive: $459.99
How the hell is Seagate supposed to provide a five year warranty on a drive that's being sold to consumers for $100? It's pretty easy to see that there is enough profit margin to cover a 5 year warranty for a $460 73GB SCSI drive.
Samsung still has 3 year warranties on their ide drives. Only one I'l buy from now.
Good for you. You can get a slower, less reliable drive with a longer warranty (I have experience on a project that used Samsung drives in over 3,000 systems). And when that $99 drive dies, you can stop working on your computer, send it back, wait for a replacement, put that in, install the OS and try to reconstruct your data. Good luck.
Hyundai and Kia cars have 10 year/100,000 mile powertrain warrantees. I guess you think that Hyundai and Kia cars are the most reliable in the world.
Also we shouldn't begrudge poorer nations our help.
I agree with this totally. In fact, I am sickened by the fact that we can find the money to wage war in Iraq but can't find the money to save millions of people who are starving to death in Ethiopia.
But we should begrudge those nations our jobs when we have the highest unemployment in decades. At times like this, the U.S. government, and, yes, U.S. corporations, should be concerned with the well-being of U.S. citizens.
Some guy being paid $2.80 per day in China to build Sears Crafsman drill presses is not going to be buying a Sears Craftsman drill press anytime soon. I think that we are already seeing the effects of U.S. businesses poisoning the well by outsourcing U.S. jobs. Consumers have less money to spend and those who do have it are hesitant to spend, not knowing if they will find themselves victims of outsourcing in the near future.
I would think that the US would want Asia to develop more so they could become greater trading partners.
I can't speak for the U.S., but what I have seen as a result of the development of Asia is outsourcing of U.S. jobs. Everything from tech support to engineering to manufacturing is being outsourced. I'm sure that makes some U.S. CEOs very happy, but it does nothing for the millions of Americans who, as a result, are out of work. Since China, for example, can be largely self-sufficient, the opportunities for export to China are limited and will remain that way until wages more or less equalize between the U.S. and China. While that is somewhat of an oversimplification in that it does not take into account worker efficiency or the costs to transport goods, it's basically true. Chinese citizens won't buy an American-made widget that when the Chinese-made widget is a fraction of the cost due to lower Chinese production costs. This cost differential will lead to an ever greater trade imbalance, with the U.S. importing Chinese goods and exporting U.S. jobs.
I can hardly get upset about China's inability to make do with the IP address space we so graciously provided them. Development of the Internet and its basic protocols (IP, TCP/IP, UDP, ettc.) was done by the U.S. at U.S. taxpayer expense. Yeah, I know that others later created applications that used those protocols (like HTTP), but the U.S. invented everything from Ethernet to the IP protocol, so we are entitled to as great a percentage of IPV4 as we want.
The above was not a troll. It was what I truly believe. Don't like it? Then debate like a man instead of trying to hide what I say with negative moderation.
I can hardly get upset about China's inability to make do with the IP address space we so graciously provided them. Development of the Internet and its basic protocols (IP, TCP/IP, UDP, ettc.) was done by the U.S. at U.S. taxpayer expense. Yeah, I know that others later created applications that used those protocols (like HTTP), but the U.S. invented everything from Ethernet to the IP protocol, so we are entitled to as great a percentage of IPV4 as we want.
I got a job, a really nice one.. :D
Find really nice jobs for the 6% of Americans out of work and the economy will recover just fine.
I'm just saying, GWB got a larger percent of the popular vote in 200 than Clinton did in 1992. If GWB doesn't have a mandate, clinton didn't either.
Fine. Clinton didn't have a mandate. Neither does Bush. The economy was great under Clinton. It sucks under Bush. Who the f*** cares about a "mandate?" Most people are more concerned about having a job and not losing their life's savings.
I love getting uptight liberals pissed off. It is nice!
Saying stupid shit is a great way to do it. Good job.
And when did this recession start? During the Clinton administration! It has leveled off and started a slow climb up.
Bull. The stock markets keep falling. Unemployment keeps rising. Economists are now in fear of deflation. Bush's plan is to do deficit spending so recklessly that we pay interest on the debt he accrues for years to come -- just as happened under Reagan and Dubya's dad, when the national debt skyrocketed. When Clinton took office, 25% of every federal tax dollar taken in was spent paying interest on the debt.
I guess everyone can't spend anymore, because most americans have racked up a fortune in credit card debt in the '90's.
Coming from a borrow-and-spend Republican, you have a lot of nerve. Bush is burying this country in debt by cutting taxes while massively increasing federal spending, racking up the largest ever deficit. When the President can't see a disadvantage to massive borrowing, how can you fault the public for doing the same thing?
Unemployed people aren't spending money because they don't have income. It's not "credit card debt." It's unemployment. It's a lack of consumer confidence. And that's the fault of the current President, not the one that left office in 2000.
Clinton inherited a recession from George Bush and Clinton's economic policies got us out of that debt and lead us to the most economically productive 8 years in the history of this country. Bush has been in office since 2001 and the economy is still in a death spiral.
Everybody has the hangover right now from the crazy uncontrolled growth in the '90's, and right now we are slowly recovering from Clinton's recession.
I guess we won't have any of that "uncontrolled growth" to worry about as long as Dubya's at the helm. Nope. I've seen no sign of it.
I was talking 1992 not 1996.
Well, I was talking about 1996 and since I'm the only one that named numbers, that's the year we will talk about.
Clinton still didn't get 50% in 1996 either, but he didn't get near that in 1992....
And what would GWB have gotten if there had been a strong third-party candidate that got 19% of the vote? You are comparing what was, essentially, three-way elections to a two-way election. What kind of way is that to judge a candidate's popularity?
Yeah, but Clinton didn't get over 50% of the popular vote though! So did he really have a mandate.
In 1992 and 1996, when Clinton won the Presidential elections, Perot was a strong candidate, taking 19% of the vote in 1992 and 8% of the vote in 1996. The strongest candidate compared to Gore and Bush was Nader, who only garnered a mere 2.74% of the vote of the popular vote in 2000. Had Perot not run, Clinton would have been well over the 50% mark (since he hit 49% in 1996 even with Perot in the race).
GWB actually had a larger % of the popular vote than Clinton did....
Says who? Rush Limbaugh? G. Gordon Liddy? Some other right-wing radio blowhard? Whoever said it, it's a load of crap. In 1996, Clinton got 49% of the popular vote while, in 2000, GWB only got 47.37% of the vote (Gore got 48.38%).
And aren't we doing well since Bush took office? We're in a recession. Unemployment is higher than it has been in years. Wages are down. Jobs are being exported overseas. The deficit spending is the highest it has ever been. And Bush and the Republican Congress just pushed through a tax windfall for the rich. We've ruined our credibility by claiming Iraq had "Weapons of Mass Destruction" and then, after invading the country, being unable to find any of the supposed weapons. I'll be so happy when GWB is booted out of office and replaced with someone who understands that deficit spending is crippling our economy and that we don't have a right to impose our will on the rest of the world.
I thought that the PADI tables are not the same as USN tables.
They are not the same as the Navy tables, however, they were initially very close.
Another point is that the USN tables assume a younger and fitter diver. PADI has to use a tissue model for a much wider range of body types (for non divers here, the amount of nitrogen held by different types of tissue, i.e., muscle, fat, is variable).
Also true. Although earlier PADI tables were simply USN tables with more conservative times rather than being based on scientific research into nitrogen uptake of various tissue types.
However, that last bit you say about trying to dive with a buddy with a different computer is one of the best ideas.
So many diving couples make the mistake of getting matching dive computers when that is, in fact, the last thing that you want. The two divers profiled in the story both used the defective UWATEC dive computers. Had either of them had a different model, they would probably have recognized the problem before it was a life-threatening danger.
Like you, I also believe in backups. I have three ways to measure my depth: Computer, analog depth gauge, and Citizen watch with depth gauge. I time the dive using both the watch and the computer. I take waterproof dive tables with me in the pocket of my BC. And that's not even counting the duplication that I get when my buddy has her computer, watch, and depth gauge.
Diving gear is life-support equipment. I find it disgusting when dive shops peddle regulators, consoles, tanks, and BCs based on color coordination rather than on design, construction, and reliability.
Don't forget that, for years, the PADI dive tables were Navy Dive Tables. For a very good history of dive tables, click here. Dive tables are based on the same theories and technology as dive computers. The biggest difference is that they are more prone to human error than are dive computers.
It's great to say "plan your dive and dive your plan", but people are fallible. Your buddy may go a little deeper than he/she intended. You may, because of narcosis, get confused about the maximum time or depth. You or they might have problems that slightly delay your ascent. If you plan to go to 90 feet and you drop a video camera to the bottom at 110, unless you're Bill Gates, you're probably going to go get the camera and cut the dive short. So much for the plan. (I've been a diver for over fifteen years. I've seen everything from divers getting entangled in wrecks to outright equipment failures. Don't reply with some macho explanation of how you can foresee and prevent every error. You can't and if you believe that you can, then you need to stop diving until your ego and testosterone stop affecting your reasoning.)
My buddy and I each bought dive computers at the same time. I made it a point to choose dive computers from different manufacturers so that a sofware flaw in one would not put us at undue risk. We stick close together and always use the more conservative of the two computer readings. Had one of us had a UWATEC computer, we would have noticed the problem immediately when comparing the two computers.
I'd sure like to see this brain surgeon try and find out who's on my whitelist and forge their address.
That must be really handy when you are advertising something for sale, providing your e-mail address on a resumé that you post, or handing out business cards with your e-mail address on them. Blocking all e-mail not from whitelisted addresses is one way to make e-mail unusable.
I cannot help but notice that people are in a company for 15-20 years, but still do not find themselves in a position to make these decisions.
Yet they feel comfortable complaining about the decisions made by the ones who are in that position.
If management is "comfortable" criticizing the work of those people who have chosen a career in software engineering, why shouldn't software engineers criticize the work (i.e., decisions) of those who have chosen a career in management? Many software engineers are in that field because they enjoy the work. They don't aspire to be managers. Criticizing them because they have not become managers is invalid.
But who's waiting to take over for the COBOL programmers? No one now, no one coming soon, and no one in the forseeable future. That's the problem.
If COBOL programmers were paid as handsomely as executives and corporate attorneys, you would find plenty of people eager to learn COBOL.
This is not some big mystery. Why would someone in the IT field go that direction when COBOL programmers are paid more poorly, have less opportunity for advancement, and generally do less rewarding work? It's like paying teachers $20K per year and wondering why more people aren't getting teaching degrees.
The pay is the problem.