With proper impedance matching networks and reasonable termination at the ends of a run you can send separate signals at the same frequency/band of frequencies down a cable in each direction. (Impedance discontinuities DO reflect some of the signal going one way back the other way, causing some interference. But even that can be "tuned out" by suitable corrections if it's too severe to just ignore.)
You can do it on a balanced pair, too. Telephones have done this with audio for more than a century, and I recall encountering a simple hack to do it all the way down to DC back in the days of discrete-transistor logic. (And it has nothing to do with two wires being involved, either. With N (= any power of 2) conductors and "phantoming" you can have up to N-1 balanced and one unbalanced two-way transmission lines on N wires.
Time Domain Reflectometry does this to FIND and MEASURE discontinuities in a cable, essentially firing a pulse down the cable and listening to the reflections, radar-style.
There is no security on the CAN communications of any modern vehicles that I know of. Any person connected to the bus can masquerade as anyone else.
That's why Tesla has several layers of bus, with firewalls between them, inside each car.
Get on one of the buses, you get to tweak the stuff on THAT bus. But you have to convince a firewall you're cool (i.e. doing something the firewall recognizes as legitimate) before it forwards your transaction to anything on even an adjacent bus.
In most countries the government is in charge of health care and they have a VERY easy way to regulate price gouging such as this. In any single payer system the national health service basically sets the price they are willing to pay and that's what it costs. End of story.
Well, not quite.
In any price control regime, the authority sets the price, and there are three options:
1. They HAPPEN to hit the "market clearing" price on the nose.
2. They set the price lower.
3. They set the price higher.
1. is a small target, and very hard to get right even if you're trying. (Even market economies only get there by constant feedback in the form of purchase decisions.) Further, there are strong political pressures on regulators on where to set prices, so they aren't even trying. So 1 just doesn't happen.
2. means the consumer gets gouged. (But now he can't go to some competitive supplier to get the product or service at a better price. EVERYBODY who is selling is selling at that price. So the gouging is institutionalized. The only way to get a lower price is to apply pressure to the regulators (see 1.) or go to a black market (with lots of risks, including issues of quality, reliability, contract enforcement, and bad encounters with law enforcement and the rest of the legal system).
3. is where the regulators usually end up. But a price lower than market-clearing means suppliers chose to spend their resources supplying something else, so the supply dries up. You could buy it at a sale price IF you could buy it at all. But it isn't available, so you can't buy it at any price.
A free market has its own problems. For starters, with a single supplier (a monopoly) market forces encourage gouging. With two suppliers they encourage an approximately even division of the market (a duopoly) and, again, gouging, with only price signals, not collusion, to coordinate their behavior. The incentive to engage in competition that drives the prices down to market-clearing level doesn't appear until there are three players, and doesn't become strong until there are four or more.
(Unfortunately, US regulations generally have a built-in assumption that two suppliers are "competition". Thus you get things like the landline/cable internet duopoly, or the built-into-channel-allocations local duopoly (collapsing to local monopolies) of the early, analog, cellphone system.)
Back in the 1970s I was an undergraduate at a highly-ranked math department. One of the professors there had no eyes. (It was a birth defect - they had not formed, and his face was slightly collapsed where they should have been.)
When a student would try to skip doing some part of a rigorous proof by substituting a geometric drawing, the other profs would ask "How would you explain it to [him]?".
This guy was VERY good. But he had a "blind spot" occasionally when a graphic analogy would have pointed him to some existing proof that would apply. (I recall once when he was discussing some bottleneck in what he was working on and another professor pointed out that the troublesome piece of the problem was equivalent to an angle trisection with compass and ruler.)
Can you please convert that to Olympic swimming pools or football fields? I am american. Thanks!
So am I. Let's see...
10,000 gram moles of x-ray photons...
Take 22 pounds of hydrogen. Turn each atom of hydrogen into an x-ray photon.
Hydrogen bombs do something like that... But let's use total annihilation because the numbers are easier to find.
1 gm of antimatter + 1 gm of matter -> 43 kilotons of TNT equivalent. So call it 21.5 kilotons per gram.
Energy equivalent of a proton's mass is really close to 1 GEv. We don't know what energy x-rays they were detecting, so let's use the energy of photons from a typical dental x-ray machine: 70 kEv. So 10^4 * 7*10^4 / 10^9 = 0.7 grams of energy, or about 15 kilotons of TNT-equivalent emitted per measurement interval.
The Hiroshima bomb was estimated at 15 kilotons, Nagasaki at 20. So call it "Almost exactly one Hiroshima bomb" or "3/4 of one Nagasaki bomb" of x-ray energy released during the observation interval.
(Or maybe boost it up a bit, because I assumed perfect efficiency for the x-ray telescope's mirrors and detector, which I suspect is quite optimistic.)
I don't know any company that's fallen further or faster in consumer esteem (once upon a time, a time I still recall, HP calculators represented the pinnacle of consumer esteem) except perhaps for the Hudson's Bay Company, but to comprehend that story you have to know what it once owned: a list of assets many nation states would envy. They spun off oil companies, railroads, real estate. What did they keep? Zellers.
Easiest method is car exhaust into a closed container via some tube.
Not since emission controls got good. There's essentially no CO (or NOx) in exhaust these days (unless, sometimes, if the car is in the sealed room and also breathing its own exhaust.) It's just a hotter and wetter version of the CO2 suffocation method.
Stealth sucks when there are multiple radars from different aspects, or using longer wave radar that stealth can't hide from.
Or radar systems where the transmitting and receiving system are separated: Those shapes are all about sending the radar signal anywhere BUT back where it came from.
(Or is that what you were talking about when you said "multiple radars from different aspects"?)
Of course the shapes are really good at their intended reflect-it-somewhere-else mode. (The engineers knew they had it right when they opened the hanger one morning and found a bunch of dead bats that had crashed into the airframe during the night. The shape had the same effect on bat sonar.)
From what I can gather it is some kind of foam that is intended to prevent tank fires, fuel sloshing and as part of the aircraft leak prevention measures.
So it's a foam that (among its functions) seals leaks.
And it's peeling off the inside of the tank.
If a piece of that gets sucked over to the fuel feed it should seal up that "leak" pretty effectively. Then again, if it gets sucked into the fuel line it might seal the engine's injectors, or the fuel filter.
Seriously? You woke me up to read about seven photons from across the other side of the solar system?
How big is the detector? How far is it from Pluto?
They detected them from the Chandra X-ray Observatory, which is in orbit around the Earth. That puts the distance between the detector and Pluto at somewhere between 29 and 50 astronomical units of about 93 million miles each, depending on where the Earth and Pluto were in their orbits during the observations.
- Calculate the area of a sphere of that radius. (That's about 10^20 square miles at the low end, abut three times that at the high end.)
- Divide by the aperture of the x-ray telescope (0.43 sq ft), in square miles. (i.e. multiply by 1.3*10^7.) We're now in the 10^27 order of magnitude.
- Assume the x-rays are ONLY the result of solar wind bombardment? Divide by two. (You'd have to do that more than three times to drop the number by even ONE order of magnitude.)
- Multiply by seven photons detected.
That's a lot of photons emitted by the planet, isn't it?
By the above argument, ANY planet, dwarf planet, moon, or other solid object of substantial size, without a strong magnetic field (which would ALSO be noticeable), should be emitting some x-rays from solar wind and cosmic ray bombardment.
If this is true, perhaps this x-radiation could be used as a basis for detection of such objects?
Why all this insistence on mechanisms involving an atmosphere? X-ray tubes don't require gas.
You get X-rays whenever you abruptly stop or deflect a fast enough charged particle (such as an electron). Pluto is a ("dwarf") PLANET, with no (known) planetary magnetic field to deflect the solar wind or cosmic radiation. Such a BIG solid body, even 'way out there from the sun, should be stopping LOTS of charged particles all the time.
(Sure, charged particles stop more "abruptly", and thus release more energetic photons, when hitting heavy atoms rather than things like hydrogen. But some of the incoming stuff will be fast enough to emit x-rays even when slamming into the bare photon of a hydrogen nucleus. And then there's the inverse case when an incoming heavy nucleus from cosmic radiation hits an electron.)
(CO2 painful, N2 just go to sleep forever. Lattter much more humane.)
I agree completely.
I've had occasion to have to euthanize animals (notably skunks) and have used the Dry Ice in the Garbage Can method, as recommended by animal control.
I've wanted to switch to nitrogen. Unfortunately, liquid nitrogen is not as readily available (dry ice is available at most grocery stores around here). I looked into getting a nitrogen bottle and the equipment needed to use it (regulator, hose). Unfortunately it was very expensive by comparison - like several hundred bux.
Rats are very clean animals. Except, you know, for:...
They're also very friendly and cuddly. They tend to get into cribs with human infants and treat them like fellow rats: Cuddle up, clean their ears, etc.
Unfortunately, rats react to a dead rat in the burrow by eating it. Humans, when they first fall asleep, tend to be in a deep sleep for something like 25ish minutes, from which it is very hard to rouse them - even by a rat bite. 25ish minutes is long enough for rats to decide a baby or child might be dead, test it by nibbling, then start chewing...
No, rats. The fleas are just a vector to get it from rats to people.
Specifically, it was the black rat, which is migratory and wandered around, spreading the plague.
One of the reasons we don't have all that much plague these days is that the Norwegian Brown Rat, which tends to hang around in a small territory, displaced the Black Rat.
The beauty of CO2 is that it's heavier than air and will fill the entire burrow. Nitrogen is about as dense as the air itself (which is 79% nitrogen anyway), so the effect won't be there.
Liquid nitrogen is liquid and much heavier than air. It will seek low spots.
Freshly evaporated gassious nitrogen is cold. Cold gasses are more dense than warmer ones and thus also seek low places.
So liquid nitrogen will produce cold nitrogen gas which will also remain in the burrow and displace the oxygen, much like the (heavier) carbon dioxide, though it's only heavier due to its lower temperature. This will produce humane suffocation by lack of oxygen without a corresponding increase in the (detectable by the respiratory system) carbon dioxide that provides the sensation of suffocation. The rats will just go to sleep and die in their sleep.
How can hardware with expensive OS cost less than one with free OS?
1. Economy of scale: They sell more of them to the vast population of Windows-only suckers and can distribute the fixed costs over more units, lowering that cost per-unit. 2. Bloatware: Companies pay them to include their products in the install. The money from that can be split between boosting the manufacturer's bottom line and lowering the consumer's price. 3. Different (possibly more expensive - especially in small volumes) peripheral hardware. 4. PROFIT!
Sadly we have a delicate situation that is best left to the courts because anything else is going to get politicized like mad.
We have a situation where the central issue is the interpretation of the law as applied to a particular situation and determination of whether an executive-branch's actions are in obedience to it. The courts are the appropriate venue for decisions of this nature.
If I actually had a need to suppress my whereabouts, just having a cell phone that is paid with a credit card pretty much defeats that.
"paid with a credit card"? It is to laugh.
Try "purchased and recharged with cash, while wearing a ski mask and having walked to (then returning from) the convenience store from a car with its license plates covered and parked away from traffic cameras (if you can find such a place within walking distance of a convenience store)."
And leave the phone off except when making a call - and then walk away from home and car to do it.
(Did you know the federally-mandated tire pressure warning system has the fill valves on each of your tires transmitting a unique serial number which can be read by loops in the road or antennas beside it?)
Slashdot Mirror
Coax is half-duplex too
No, it's not.
With proper impedance matching networks and reasonable termination at the ends of a run you can send separate signals at the same frequency/band of frequencies down a cable in each direction. (Impedance discontinuities DO reflect some of the signal going one way back the other way, causing some interference. But even that can be "tuned out" by suitable corrections if it's too severe to just ignore.)
You can do it on a balanced pair, too. Telephones have done this with audio for more than a century, and I recall encountering a simple hack to do it all the way down to DC back in the days of discrete-transistor logic. (And it has nothing to do with two wires being involved, either. With N (= any power of 2) conductors and "phantoming" you can have up to N-1 balanced and one unbalanced two-way transmission lines on N wires.
Time Domain Reflectometry does this to FIND and MEASURE discontinuities in a cable, essentially firing a pulse down the cable and listening to the reflections, radar-style.
My wife was looking over my shoulder when the "Cisco Blamed A Router Bug on 'Cosmic Radiation'" headline went by, and asked:
"What's their next excuse? Global Warming?"
Does it support Intel Advanced Management Technology?
After all, you wouldn't want an embedded controller the NSA didn't have access to, would you? The terrorists might win!
There is no security on the CAN communications of any modern vehicles that I know of. Any person connected to the bus can masquerade as anyone else.
That's why Tesla has several layers of bus, with firewalls between them, inside each car.
Get on one of the buses, you get to tweak the stuff on THAT bus. But you have to convince a firewall you're cool (i.e. doing something the firewall recognizes as legitimate) before it forwards your transaction to anything on even an adjacent bus.
In most countries the government is in charge of health care and they have a VERY easy way to regulate price gouging such as this. In any single payer system the national health service basically sets the price they are willing to pay and that's what it costs. End of story.
Well, not quite.
In any price control regime, the authority sets the price, and there are three options:
1. They HAPPEN to hit the "market clearing" price on the nose.
2. They set the price lower.
3. They set the price higher.
1. is a small target, and very hard to get right even if you're trying. (Even market economies only get there by constant feedback in the form of purchase decisions.) Further, there are strong political pressures on regulators on where to set prices, so they aren't even trying. So 1 just doesn't happen.
2. means the consumer gets gouged. (But now he can't go to some competitive supplier to get the product or service at a better price. EVERYBODY who is selling is selling at that price. So the gouging is institutionalized. The only way to get a lower price is to apply pressure to the regulators (see 1.) or go to a black market (with lots of risks, including issues of quality, reliability, contract enforcement, and bad encounters with law enforcement and the rest of the legal system).
3. is where the regulators usually end up. But a price lower than market-clearing means suppliers chose to spend their resources supplying something else, so the supply dries up. You could buy it at a sale price IF you could buy it at all. But it isn't available, so you can't buy it at any price.
A free market has its own problems. For starters, with a single supplier (a monopoly) market forces encourage gouging. With two suppliers they encourage an approximately even division of the market (a duopoly) and, again, gouging, with only price signals, not collusion, to coordinate their behavior. The incentive to engage in competition that drives the prices down to market-clearing level doesn't appear until there are three players, and doesn't become strong until there are four or more.
(Unfortunately, US regulations generally have a built-in assumption that two suppliers are "competition". Thus you get things like the landline/cable internet duopoly, or the built-into-channel-allocations local duopoly (collapsing to local monopolies) of the early, analog, cellphone system.)
Back in the 1970s I was an undergraduate at a highly-ranked math department. One of the professors there had no eyes. (It was a birth defect - they had not formed, and his face was slightly collapsed where they should have been.)
When a student would try to skip doing some part of a rigorous proof by substituting a geometric drawing, the other profs would ask "How would you explain it to [him]?".
This guy was VERY good. But he had a "blind spot" occasionally when a graphic analogy would have pointed him to some existing proof that would apply. (I recall once when he was discussing some bottleneck in what he was working on and another professor pointed out that the troublesome piece of the problem was equivalent to an angle trisection with compass and ruler.)
I hate to jump the gun here, but could it possibly be antimatter?
Then they'd be calling them "gamma rays", not "x-rays", and would have found them with a different orbital telescope.
Can you please convert that to Olympic swimming pools or football fields? I am american. Thanks!
So am I. Let's see...
10,000 gram moles of x-ray photons...
Take 22 pounds of hydrogen. Turn each atom of hydrogen into an x-ray photon.
Hydrogen bombs do something like that... But let's use total annihilation because the numbers are easier to find.
1 gm of antimatter + 1 gm of matter -> 43 kilotons of TNT equivalent. So call it 21.5 kilotons per gram.
Energy equivalent of a proton's mass is really close to 1 GEv. We don't know what energy x-rays they were detecting, so let's use the energy of photons from a typical dental x-ray machine: 70 kEv. So 10^4 * 7*10^4 / 10^9 = 0.7 grams of energy, or about 15 kilotons of TNT-equivalent emitted per measurement interval.
The Hiroshima bomb was estimated at 15 kilotons, Nagasaki at 20. So call it "Almost exactly one Hiroshima bomb" or "3/4 of one Nagasaki bomb" of x-ray energy released during the observation interval.
(Or maybe boost it up a bit, because I assumed perfect efficiency for the x-ray telescope's mirrors and detector, which I suspect is quite optimistic.)
How's that?
I don't know any company that's fallen further or faster in consumer esteem (once upon a time, a time I still recall, HP calculators represented the pinnacle of consumer esteem) except perhaps for the Hudson's Bay Company, but to comprehend that story you have to know what it once owned: a list of assets many nation states would envy. They spun off oil companies, railroads, real estate. What did they keep? Zellers.
Two words: Carly Fiorina.
Easiest method is car exhaust into a closed container via some tube.
Not since emission controls got good. There's essentially no CO (or NOx) in exhaust these days (unless, sometimes, if the car is in the sealed room and also breathing its own exhaust.) It's just a hotter and wetter version of the CO2 suffocation method.
Stealth sucks when there are multiple radars from different aspects, or using longer wave radar that stealth can't hide from.
Or radar systems where the transmitting and receiving system are separated: Those shapes are all about sending the radar signal anywhere BUT back where it came from.
(Or is that what you were talking about when you said "multiple radars from different aspects"?)
Of course the shapes are really good at their intended reflect-it-somewhere-else mode. (The engineers knew they had it right when they opened the hanger one morning and found a bunch of dead bats that had crashed into the airframe during the night. The shape had the same effect on bat sonar.)
From what I can gather it is some kind of foam that is intended to prevent tank fires, fuel sloshing and as part of the aircraft leak prevention measures.
https://en.wikipedia.org/wiki/...i
So it's a foam that (among its functions) seals leaks.
And it's peeling off the inside of the tank.
If a piece of that gets sucked over to the fuel feed it should seal up that "leak" pretty effectively. Then again, if it gets sucked into the fuel line it might seal the engine's injectors, or the fuel filter.
Any of those could make the engine suddenly stop.
Oops!
"That's a lot of photons emitted by the planet, isn't it?"
Avogadro's number is only about 6*10^23, so we're talking something like ten thousand gram-moles of x-rays emitted during the observation period.
Ten Thousand Gram Moles of x-ray photons? Yike!
Seriously? You woke me up to read about seven photons from across the other side of the solar system?
How big is the detector? How far is it from Pluto?
They detected them from the Chandra X-ray Observatory, which is in orbit around the Earth. That puts the distance between the detector and Pluto at somewhere between 29 and 50 astronomical units of about 93 million miles each, depending on where the Earth and Pluto were in their orbits during the observations.
- Calculate the area of a sphere of that radius. (That's about 10^20 square miles at the low end, abut three times that at the high end.)
- Divide by the aperture of the x-ray telescope (0.43 sq ft), in square miles. (i.e. multiply by 1.3*10^7.) We're now in the 10^27 order of magnitude.
- Assume the x-rays are ONLY the result of solar wind bombardment? Divide by two. (You'd have to do that more than three times to drop the number by even ONE order of magnitude.)
- Multiply by seven photons detected.
That's a lot of photons emitted by the planet, isn't it?
By the above argument, ANY planet, dwarf planet, moon, or other solid object of substantial size, without a strong magnetic field (which would ALSO be noticeable), should be emitting some x-rays from solar wind and cosmic ray bombardment.
If this is true, perhaps this x-radiation could be used as a basis for detection of such objects?
Why all this insistence on mechanisms involving an atmosphere? X-ray tubes don't require gas.
You get X-rays whenever you abruptly stop or deflect a fast enough charged particle (such as an electron). Pluto is a ("dwarf") PLANET, with no (known) planetary magnetic field to deflect the solar wind or cosmic radiation. Such a BIG solid body, even 'way out there from the sun, should be stopping LOTS of charged particles all the time.
(Sure, charged particles stop more "abruptly", and thus release more energetic photons, when hitting heavy atoms rather than things like hydrogen. But some of the incoming stuff will be fast enough to emit x-rays even when slamming into the bare photon of a hydrogen nucleus. And then there's the inverse case when an incoming heavy nucleus from cosmic radiation hits an electron.)
(CO2 painful, N2 just go to sleep forever. Lattter much more humane.)
I agree completely.
I've had occasion to have to euthanize animals (notably skunks) and have used the Dry Ice in the Garbage Can method, as recommended by animal control.
I've wanted to switch to nitrogen. Unfortunately, liquid nitrogen is not as readily available (dry ice is available at most grocery stores around here). I looked into getting a nitrogen bottle and the equipment needed to use it (regulator, hose). Unfortunately it was very expensive by comparison - like several hundred bux.
Rats are very clean animals. Except, you know, for: ...
They're also very friendly and cuddly. They tend to get into cribs with human infants and treat them like fellow rats: Cuddle up, clean their ears, etc.
Unfortunately, rats react to a dead rat in the burrow by eating it. Humans, when they first fall asleep, tend to be in a deep sleep for something like 25ish minutes, from which it is very hard to rouse them - even by a rat bite. 25ish minutes is long enough for rats to decide a baby or child might be dead, test it by nibbling, then start chewing...
Fleas.
No, rats. The fleas are just a vector to get it from rats to people.
Specifically, it was the black rat, which is migratory and wandered around, spreading the plague.
One of the reasons we don't have all that much plague these days is that the Norwegian Brown Rat, which tends to hang around in a small territory, displaced the Black Rat.
The beauty of CO2 is that it's heavier than air and will fill the entire burrow. Nitrogen is about as dense as the air itself (which is 79% nitrogen anyway), so the effect won't be there.
Liquid nitrogen is liquid and much heavier than air. It will seek low spots.
Freshly evaporated gassious nitrogen is cold. Cold gasses are more dense than warmer ones and thus also seek low places.
So liquid nitrogen will produce cold nitrogen gas which will also remain in the burrow and displace the oxygen, much like the (heavier) carbon dioxide, though it's only heavier due to its lower temperature. This will produce humane suffocation by lack of oxygen without a corresponding increase in the (detectable by the respiratory system) carbon dioxide that provides the sensation of suffocation. The rats will just go to sleep and die in their sleep.
Are the hardware back doors (such as Intel AMT) disabled (or disablable) on the Linux version?
How can hardware with expensive OS cost less than one with free OS?
1. Economy of scale: They sell more of them to the vast population of Windows-only suckers and can distribute the fixed costs over more units, lowering that cost per-unit.
2. Bloatware: Companies pay them to include their products in the install. The money from that can be split between boosting the manufacturer's bottom line and lowering the consumer's price.
3. Different (possibly more expensive - especially in small volumes) peripheral hardware.
4. PROFIT!
Sadly we have a delicate situation that is best left to the courts because anything else is going to get politicized like mad.
We have a situation where the central issue is the interpretation of the law as applied to a particular situation and determination of whether an executive-branch's actions are in obedience to it. The courts are the appropriate venue for decisions of this nature.
If I actually had a need to suppress my whereabouts, just having a cell phone that is paid with a credit card pretty much defeats that.
"paid with a credit card"? It is to laugh.
Try "purchased and recharged with cash, while wearing a ski mask and having walked to (then returning from) the convenience store from a car with its license plates covered and parked away from traffic cameras (if you can find such a place within walking distance of a convenience store)."
And leave the phone off except when making a call - and then walk away from home and car to do it.
(Did you know the federally-mandated tire pressure warning system has the fill valves on each of your tires transmitting a unique serial number which can be read by loops in the road or antennas beside it?)
It's true that prohibition fostered the creation of a huge amount of organized crime, but there were plenty of drunks before prohibition.
But there were a LOT MORE, among college-age especially, during it than before. Which was my point.