While the project is probably fun for anon, this setup misses pretty much all advantages of DLSR. To mention a few:
* Autofocus in most lenses * Measuring focus before, on and after the plane of the sensor, making for even faster focus calculations * Cleaner exposure with less movement artefacts due to mechanical shutter * Less noise in the pictures because the sensor is not needed for viewfinding and thus does not heat up * Large image sensor
And prolly a dozen I forgot about. You may now return to normal/. mode and continue discussing details without reading the article:p
Disclaimer: The mechanism is the same, but the numbers are prolly off. Also, red blood cells are good at keeping oxygen; my calculation assumes dilution in liquids, not proper blood. Again: The figures are off, but this is the correct mechanism.
Let's assume you are breathing normal air at 1 bar.
1 bar * 21% oxygen = 0.21 bar oxygen
As you know, you exhale about 17% oxygen; let's assume your oxygen level in returning blood is about 13% (I am not sure, sorry. Yet that fits the 12% figure from earlier). As your body needs about a minute to pump all 5 liters of blood through your body when at rest, you arrive at the usual maximum of one minute. Though again, the rising panic you feel when you hold your breath is rising level of CO_2, not dimishing O_2.
Now, take a lung-full of 0% oxygen. Your blood arrives with 13% oxygen in it and leaves with 6.5%. As your blood takes the fast (and thick) lane to your brain, the effect happens fast.
To all doctors etc: If you have better figures, _please_ correct me.
> A young man died cave diving in the Rockies not far from Calgary a few years back. The awful bit was that he got delayed coming back, wasn't sure how far it was, went to the limit of his air, turned the little knob that gives you the last five minutes, and used that time scratching out a goodbye to his family on the air tank.
That places him in the 70ies, roughly speaking. Technology and procedures have advanced a _lot_ since then.
Look at the statistics: The people who die in caves are untrained, under-/overequipped or old-timers trying to break a record or two.
> Then you start using gear that has no business being in a cave: scooters and rebreathers. Both of which can get you further into the cave than have any business being, when complacency causes you to fail to lay the groundwork for your escape in the event of an equipment failure.
I call bullshit. Of course, you need at least one spare scooter and rebreather, but there is no reason not to use them _if done right_. The active scooter has a rebreather built into it. Spare rebreather on your back, spare scooter[s] dangling from your back crotch ring.
1) They use steel capsules. Inflatables would be a joke.
2) You have extra air on your back, on your scooter and in your dry habitat, if any. On the most modest of trips, you will have 3/2 times as much air as you need for the entire dive, though the trend is to take double the amount.
3) You don't need an airlock. Just flood the thing with a gas mix suitable for the depth it's in and maintain oxygen level.
4) Every SCUBA, be it open, semi-closed or closed-circuit has to maintain ambient pressure anyway. You don't have muscles to breathe. You simply release your muscles and your lung expands. Same thing works under water.
5) To fill a habitat, you don't even need pressure equalisation. Simply open a tank and let it flood the habitat. Physics will take care of the rest.
> It'd be nuts to "free" dive in caves, without a rope or some other guide back.
Correct. There was one free dive in the Blue Hole in Dahab, but that was guarded heavily and not a proper cave, if in an overhead environment.
> For these extreme dives you'd think they'd also work their way down with spare air tanks so they never had to worry about going all the way back up to the top, just back to the last air tank drop.
While you usually tend to come back the same way, people like to carry all their gas with them. Same for scooters etc.
> I also wonder if they couldn't engineer some kind of capsule that could be inflated in a larger chamber to serve as a base on longer dives, possibly with an air line from the surface, sort of a base camp.
They are doing this in various long-term mapping projects. To see an example, go to: http://www.ekpp.org/
Whoever modded you insightful has never seen a proper SCUBA diver. It's the least sexy sport, bar none.
Unless you build a pee valve into your dry suit, the only way to take a leak in a dry-suit are diapers. Yes, diapers.
Add the fact that you need to stay hydrated very well and that cold water will make your body pull blood into the torso. This, in turn, makes your bladder work overtime. Being perfectly still most of the time during ascent and the nice bubbly noises all around you adds extra fun!
Dust per se does not exist as everything is wet by definition.
Still, a proper silt-out can last for up to 24 hours. I played with silt in open water and it's possible to create a cloud so dark you literally can not see your hand before your mask. And that's normal, outside silt. Not the insanely fine-grained silt in totally still water that has been sitting there for a few hundred or thousands of years.
Google for side-mount and no mount if you want some good shivers. Those guys are crazy even by cave diving standards;)
Every SCUBA diver who is not enclosed in armour (some are) breathe gas at ambient pressure. As you can see in the link above, there are various risks associated with deep diving, but the truly limiting factor are the effects of the various gases at depth. Helium and hydrogen are used to replace oxygen and nitrogen to some extent, but they come with their own set of problems. All other gases are too heavy and/or toxic and will kill you in the short or long run. Argon is the only one light enough to be breathed, but it's a _massive_ hallucinogenic.
Too much oxygen: Cramps, reduced field of vision up to and including temporal blindness. Damage to cell tissue if exposed for prolonged time (starting at 8-24 hours, depending on who you ask)
Too much nitrogen: You become stupid. The effect is gone the second you go above your personal depth limit (of the day). Also, your metabolic rate goes through the roof. You feel your entire body panicking and need to fight to stay calm. Those effects become less if you dive deep on air regularly.
Too much helium: HPNS. Your nervous system goes into overdrive; often accompied by shivering.
Too much hydrogen: I think it was narcotic, if less so than nitrogen. As it's not really used in non-professional diving I don't know too much about it. Although it's cheaper than helium, it likes to go boom. Pair that with high-pressure oxygen and the tiniest fleck of grease or oil anywhere will make everything explode all by itself.
Various side effects like helium being able to get out of solution easier, forcing you to ascend even more slowly etc pp also come into play.
Also, as any caver will tell you, unless you _know_ a cave has constant supply of fresh air, you better bring your own gas. Your body detects higher-than-normal levels of CO_2, not the absence of O_2. Under the right conditions, a lung-full of zero (or less than 12%) oxygen gas will ensure that you are unconscious before you hit the ground. After that, you suffocate and die, but at least you won't know it.
I uninstalled the app immediately and left them with a one-star rating plus a link to explain the background. Also, I uninstalled them as malicious. Feel free to link http://tinyurl.com/3a93ed8 in your one-star ratings.
Get SoundHound instead. It's better anyway. Now that I have SoundHound, I am actually glad that Shazam made me look for alternatives.
Disclaimer: If storing data, i am using RDBMS only. I learned to DB2 on OS/400 and strong relational models, so that will always be where my heart is.
Twitter does not _need_ true RDBMS features. True integrity? Why? Strong relational ties? Why? etc pp. They need to scale; massively at that. Sure, investing millions into a proper system and again as much for the backup system and then starting to invest more to spread geographically is nice for an established company with deep pockets. Sure, you might hit maximum capacity, but you can always shell out a couple dozen millions more as long as the current vendor you are locked in on has anything larger to sell you. If not, well dead end & wait for the next iteration. Or invest even _more_ migrating somewhere else.
But if you start from more or less nothing, or even just a "sane" budget, this is not an option. Period.
Also, I seem to remember this one company, I think they go by the name of Google, that scales really well; way beyond anything Twitter could hope to scale to anytime soon. They seem to do fine without RDMBS and expensive hardware.
If you submit a story, at least put minimal effort into it. Sure, there will be a few people who can compare mph with m/s, but the other 99.9999% of the human population can't. Even better, using mph & m/s, the m stands for mile and meter with nothing discerning them but common use.
30 mph = 13.4112 meters / second
Of course, Slashdot is not helping with its submission process. Either, it gets accepted or not. No "hey, fix this and we will publish it" or anything. The "fix your own crap before we accept it" system works wonderfully in FLOSS, why should Slashdot do it differently?
Here we are, ridiculing the rest of the world's population, especially the US of A, of becoming more and more idiotic all the time, but can't put the tiniest effort into anything. Oh, and any submissions that don't use metric should simply be denied.
You should add that pressure leads to an increase in spontaneous oxidation. Especially when people dive cheap and don't use oxygen-save o-rings, lubricants, etc.
As long as the NIST has not finished its current competition, there is a simple fix:
Use both Whirlpool _and_ SHA-512 (or better: SHA2 in its 512 bit variant). They are long enough to make reasonably sure no one can deduct anything about a potentially secret cleartext any time soon (there is _more_ information about the clear text in the wild, after all) while also making sure that no one will be able to create a matching clear text, both due to their length and based on the fact that they come from totally different families.
Slashdot Mirror
None of the wavelengths used to transmit data (850nm, 1330nm, 1550nm) are visible.
At least with Google Apps accounts, I have been doing this for about a month, now. And yes, it's nice.
While the project is probably fun for anon, this setup misses pretty much all advantages of DLSR. To mention a few:
* Autofocus in most lenses
* Measuring focus before, on and after the plane of the sensor, making for even faster focus calculations
* Cleaner exposure with less movement artefacts due to mechanical shutter
* Less noise in the pictures because the sensor is not needed for viewfinding and thus does not heat up
* Large image sensor
And prolly a dozen I forgot about. You may now return to normal /. mode and continue discussing details without reading the article :p
Point is, the blood is deoxygenated even _more_, depending on circumstances.
Actually, if you really wanted to get down to 2km you would use a surface-supported vessel and it would work ;)
If you are using a pressurized suit you would not dive deeper than its max depth so you would not be crushed.
Of course there are no suits that go to this depth.
Step 17: Put on sunglasses and scream YYEEEAAAAAAHHHHHHH
Disclaimer: The mechanism is the same, but the numbers are prolly off. Also, red blood cells are good at keeping oxygen; my calculation assumes dilution in liquids, not proper blood.
Again: The figures are off, but this is the correct mechanism.
Let's assume you are breathing normal air at 1 bar.
1 bar * 21% oxygen = 0.21 bar oxygen
As you know, you exhale about 17% oxygen; let's assume your oxygen level in returning blood is about 13% (I am not sure, sorry. Yet that fits the 12% figure from earlier). As your body needs about a minute to pump all 5 liters of blood through your body when at rest, you arrive at the usual maximum of one minute. Though again, the rising panic you feel when you hold your breath is rising level of CO_2, not dimishing O_2.
Now, take a lung-full of 0% oxygen. Your blood arrives with 13% oxygen in it and leaves with 6.5%. As your blood takes the fast (and thick) lane to your brain, the effect happens fast.
To all doctors etc: If you have better figures, _please_ correct me.
To anyone speaking German: http://www.gtuem.org/984/Tauchmedizin/O2-Mangel.html
Babelfish: http://babelfish.yahoo.com/translate_url?doit=done&tt=url&intl=1&fr=bf-home&trurl=http%3A%2F%2Fwww.gtuem.org%2F984%2FTauchmedizin%2FO2-Mangel.html&lp=de_en&btnTrUrl=Translate
Counter nitpick: There are armored diving suits which are actually self-contained. Though I agree that most depend on surface support.
Calling an Italian car, and a Ferrari at that, high quality is stretching things _a lot_.
> A young man died cave diving in the Rockies not far from Calgary a few years back. The awful bit was that he got delayed coming back, wasn't sure how far it was, went to the limit of his air, turned the little knob that gives you the last five minutes, and used that time scratching out a goodbye to his family on the air tank.
That places him in the 70ies, roughly speaking. Technology and procedures have advanced a _lot_ since then.
Look at the statistics: The people who die in caves are untrained, under-/overequipped or old-timers trying to break a record or two.
> Then you start using gear that has no business being in a cave: scooters and rebreathers. Both of which can get you further into the cave than have any business being, when complacency causes you to fail to lay the groundwork for your escape in the event of an equipment failure.
I call bullshit. Of course, you need at least one spare scooter and rebreather, but there is no reason not to use them _if done right_. The active scooter has a rebreather built into it. Spare rebreather on your back, spare scooter[s] dangling from your back crotch ring.
1) They use steel capsules. Inflatables would be a joke.
2) You have extra air on your back, on your scooter and in your dry habitat, if any. On the most modest of trips, you will have 3/2 times as much air as you need for the entire dive, though the trend is to take double the amount.
3) You don't need an airlock. Just flood the thing with a gas mix suitable for the depth it's in and maintain oxygen level.
4) Every SCUBA, be it open, semi-closed or closed-circuit has to maintain ambient pressure anyway. You don't have muscles to breathe. You simply release your muscles and your lung expands. Same thing works under water.
5) To fill a habitat, you don't even need pressure equalisation. Simply open a tank and let it flood the habitat. Physics will take care of the rest.
> It'd be nuts to "free" dive in caves, without a rope or some other guide back.
Correct. There was one free dive in the Blue Hole in Dahab, but that was guarded heavily and not a proper cave, if in an overhead environment.
> For these extreme dives you'd think they'd also work their way down with spare air tanks so they never had to worry about going all the way back up to the top, just back to the last air tank drop.
While you usually tend to come back the same way, people like to carry all their gas with them. Same for scooters etc.
> I also wonder if they couldn't engineer some kind of capsule that could be inflated in a larger chamber to serve as a base on longer dives, possibly with an air line from the surface, sort of a base camp.
They are doing this in various long-term mapping projects. To see an example, go to:
http://www.ekpp.org/
Whoever modded you insightful has never seen a proper SCUBA diver. It's the least sexy sport, bar none.
Unless you build a pee valve into your dry suit, the only way to take a leak in a dry-suit are diapers. Yes, diapers.
Add the fact that you need to stay hydrated very well and that cold water will make your body pull blood into the torso. This, in turn, makes your bladder work overtime. Being perfectly still most of the time during ascent and the nice bubbly noises all around you adds extra fun!
Dust per se does not exist as everything is wet by definition.
Still, a proper silt-out can last for up to 24 hours. I played with silt in open water and it's possible to create a cloud so dark you literally can not see your hand before your mask. And that's normal, outside silt. Not the insanely fine-grained silt in totally still water that has been sitting there for a few hundred or thousands of years.
Google for side-mount and no mount if you want some good shivers. Those guys are crazy even by cave diving standards ;)
Read this: http://en.wikipedia.org/wiki/Scuba_diving#Effects_of_breathing_high_pressure_gas
Every SCUBA diver who is not enclosed in armour (some are) breathe gas at ambient pressure. As you can see in the link above, there are various risks associated with deep diving, but the truly limiting factor are the effects of the various gases at depth. Helium and hydrogen are used to replace oxygen and nitrogen to some extent, but they come with their own set of problems. All other gases are too heavy and/or toxic and will kill you in the short or long run. Argon is the only one light enough to be breathed, but it's a _massive_ hallucinogenic.
Too much oxygen: Cramps, reduced field of vision up to and including temporal blindness. Damage to cell tissue if exposed for prolonged time (starting at 8-24 hours, depending on who you ask)
Too much nitrogen: You become stupid. The effect is gone the second you go above your personal depth limit (of the day). Also, your metabolic rate goes through the roof. You feel your entire body panicking and need to fight to stay calm. Those effects become less if you dive deep on air regularly.
Too much helium: HPNS. Your nervous system goes into overdrive; often accompied by shivering.
Too much hydrogen: I think it was narcotic, if less so than nitrogen. As it's not really used in non-professional diving I don't know too much about it. Although it's cheaper than helium, it likes to go boom. Pair that with high-pressure oxygen and the tiniest fleck of grease or oil anywhere will make everything explode all by itself.
Various side effects like helium being able to get out of solution easier, forcing you to ascend even more slowly etc pp also come into play.
Also, as any caver will tell you, unless you _know_ a cave has constant supply of fresh air, you better bring your own gas. Your body detects higher-than-normal levels of CO_2, not the absence of O_2. Under the right conditions, a lung-full of zero (or less than 12%) oxygen gas will ensure that you are unconscious before you hit the ground. After that, you suffocate and die, but at least you won't know it.
I uninstalled the app immediately and left them with a one-star rating plus a link to explain the background. Also, I uninstalled them as malicious. Feel free to link http://tinyurl.com/3a93ed8 in your one-star ratings.
Get SoundHound instead. It's better anyway. Now that I have SoundHound, I am actually glad that Shazam made me look for alternatives.
Again:
http://tinyurl.com/3a93ed8
http://www.soundhound.com/
PS: It would be evil to install them just to uninstall them with one-star ratings. I could not condone that.
Muphry, eh?
Disclaimer: If storing data, i am using RDBMS only. I learned to DB2 on OS/400 and strong relational models, so that will always be where my heart is.
Twitter does not _need_ true RDBMS features. True integrity? Why? Strong relational ties? Why? etc pp.
They need to scale; massively at that. Sure, investing millions into a proper system and again as much for the backup system and then starting to invest more to spread geographically is nice for an established company with deep pockets.
Sure, you might hit maximum capacity, but you can always shell out a couple dozen millions more as long as the current vendor you are locked in on has anything larger to sell you. If not, well dead end & wait for the next iteration. Or invest even _more_ migrating somewhere else.
But if you start from more or less nothing, or even just a "sane" budget, this is not an option. Period.
Also, I seem to remember this one company, I think they go by the name of Google, that scales really well; way beyond anything Twitter could hope to scale to anytime soon. They seem to do fine without RDMBS and expensive hardware.
If you submit a story, at least put minimal effort into it. Sure, there will be a few people who can compare mph with m/s, but the other 99.9999% of the human population can't. Even better, using mph & m/s, the m stands for mile and meter with nothing discerning them but common use.
30 mph = 13.4112 meters / second
Of course, Slashdot is not helping with its submission process. Either, it gets accepted or not. No "hey, fix this and we will publish it" or anything. The "fix your own crap before we accept it" system works wonderfully in FLOSS, why should Slashdot do it differently?
Here we are, ridiculing the rest of the world's population, especially the US of A, of becoming more and more idiotic all the time, but can't put the tiniest effort into anything. Oh, and any submissions that don't use metric should simply be denied.
Rant over; it's save to re-enter the building.
Why? Because lobby groups influence the WHO to say so. Warning levels become lower and lower all the time, thus _more_ people have illness X.
Why? Because then you can sell people all kinds of crap they don't really need.
You should add that pressure leads to an increase in spontaneous oxidation. Especially when people dive cheap and don't use oxygen-save o-rings, lubricants, etc.
That's what I meant by "reasonably sure", yes.
I am not aware of any research in this direction, though.
If you are paranoid, salt both hashes. With different salts.
As long as the NIST has not finished its current competition, there is a simple fix:
Use both Whirlpool _and_ SHA-512 (or better: SHA2 in its 512 bit variant). They are long enough to make reasonably sure no one can deduct anything about a potentially secret cleartext any time soon (there is _more_ information about the clear text in the wild, after all) while also making sure that no one will be able to create a matching clear text, both due to their length and based on the fact that they come from totally different families.