I once set up an ssh honeypot in a chroot jail (with noexec and hardly anything in/bin; this was in 2005, before VMs were easy to run) to see what would happen; login guest/guest. Surely someone logged in, but they didn't attempt anything once inside. Maybe they were going to come back, but I didn't wait for it.
Well, a business laptop of EUR 1000 doesn't really count as a cheap DIY solution. And my employer-supplied laptop always charges to 100% when docked, as far as I can tell. Corporate IT has blocked user access to BIOS/UEFI, so I don't know what it can do.
I once tried running an old netbook as server (dns and files, not routing) with UPS. When the power outage came, half a year later, it shut off immediately. Moreover, it didn't boot on its own when the power came back. With the lud closed, it was always kind of hot.
Apparently, Li-ion batteries need to be discharged every now and then to keep their calibration. The charging hardware seemed to think that the battery was fully charged while it was really empty. I've seen this happen as well with another laptop and a tablet.
"Keypass2 is a.Net rewrite that doesn't work well on ANY platform, and it's new format is not widely supported. The only decent feature that Keepass2 added was better multi-user support, which is pointless for most users anyway. Go with Keepass1."
As for the leading Android implementations, keepass2android is definitely better than keepassDroid. They use the same database format (kdbx). However, KPD does not black out its thumbnail in the recent-apps list, does not have the same features for auto-locking the database, and does not warn about clipboard snooping attacks. If someone grabs your phone, you're at more risk with KPD than with KP2A.
"Also, plastic clamshells tend to hold up okay when dropped"
All my laptops suffered from material fatigue in the case. Three times a crack on the right of the keyboard (from holding it with one hand), two with a severe crack on the back of the screen, near the hinges. I would welcome a small laptop (11-12 inch) that really lasts. Although among them were a 14-in Thinkpad T23 and a 14-in Dell Latitude, so it weren't just ultraportables.
And why you compare the pressure of He inside, to the partial pressure of He outside is beyond me.
Because the pressure of He inside is equal to the partial pressure of He inside.
Unless the pores in the balloon have diameters that are much larger than the mean free path length (about 50 nm at atmospheric pressure), the absolute pressure doesn't matter for the leak rate, only the partial pressure. I doubt that balloon rubber has pores that large, but it could be. Even in the likely case that the pores are small (<100 nm), the pore size may shrink as the balloon deflates, which will depress the leak rate more than what can be explained from the change in membrane thickness.
Disclosure: I am a vacuum engineer. If you don't believe it, then I suggest that you read up on the concepts of Knudsen number, Fick's law, and permeation.
I volunteered in a drug trial around 1995 or so. Back then, it paid NLG 100 per day, or EUR 70 corrected for inflation. When you're in college, that's a lot of money, especially since you can study your quantum mechanics at the same time. There was a guy who was participating in studies all the time.
It was a phase-2 trial though; the (benign) side effects were already known. Phase 1 and drugs with severe side effects paid better. And we were told what kind of medicine it was and what side effects to expect before signing.
In an inflated balloon, you have 1.05 bar of He on the inside and 0.000005 bar of He on the outside.
When the balloon is almost deflated, you have 1.00 bar of He on the inside and 0.000005 bar on the outside. So that would make the diffusion speed decrease by a whopping 5 percent.
Let me start with an appeal to authority: I actually get paid to do calculations on gas diffusion and pumping of hydrogen.
Depending on the materials of the walls of your helium-containing vessels, drawing a vacuum can take rather long. The point is that diffusive transport is driven by differences in partial pressures (or concentration if the gas is dissolved in a solid). The partial pressure of helium in the atmosphere is about 0.5 Pa; if you have a vessel with a porous wall with 100 kPa of helium (atmospheric pressure) on the inside, then helium will diffuse towards the volume with the lower partial pressure until both sides have the same partial pressure (i.e., 0.5 Pa). The same process will happen in the opposite direction for other gases (nitrogen, oxygen), but at a much slower speed. So at t=0, you have 100 kPa He (pure). After 1 year, you have (for example) 50 kPa He and 0.01 Pa nitrogen. After ten million years, you have 0.5 Pa He and close to 100 kPa nitrogen.
Just imagine that you have a box with a small hole and lot of fruit flies on the inside. Place this box next to a stable where there are lots of big flies. The fruit flies will gradually disappear from the box, but not because they are pushing each other or because the fat flies (that don't fit through the hole) are pushing them out.
For helium, diffusion speed is proportional to the difference in partial pressures on either side of the wall. For hydrogen, it's more complicated because the hydrogen molecules first need to dissociate before they can permeate through metals; it turns out that the speed of diffusion is driven by the difference in square roots of the partial pressure of hydrogen on either side.
If you have had hands-on experience with these things: do you have any idea how they handle pressure differences? Hard disk casings typically have flat sides, which are not ideal for handling pressure. In a pressurized airplane, you can have 0.3 bar pressire drop, which will exert about 30 kg of force on the walls. It's worse if they are shipped as unpressurozed cargo. So, the walls must be thicker than with a conventiomal HD, which conflicts with the goal of increasing the number of platters.
"In order for them to leak other particles need to diffuse into the drive to replace the missing atoms, it's not going to leak itself into a vacuum,"
Actually, you will draw a vacuum, provided that you wait long enough. In balloons, the process slows down not because the pressure difference decreases, but because the latex rubber layer gets thicker as the balloon shrinks.
The idea is that the thin film between the head and platter forms at a shorter distance in helium, so everything can be made smaller and closer together. As another poster pointed out, at room temperature/pressure, helium is monatomic while hydrogen forms H2 molecules, which are larger than the helium atoms.
What matters for the hydrodynamics (drag forces, lift forces on the head) is not directly the size of the molecule, but the molecular mass (related to densitiy of the gas) and the dynamic viscosity (related to both molecular mass and molecular size). The size of the molecule or atom is in any case vanishingly small compared to the distance between the head and the platter. The dynamic viscosities of a few gases at room temperature are: helium is 19 micro-Pa s, air 18 uPa s, and hydrogen 9 uPa s. The molecular masses (proportional to density) are 4, 29, and 2, respectively; this is where helium wins, but hydrogen is better both in molecular mass and viscosity.
The real reason for not using hydrogen gas is that hydrogen (H2) is reactive; at surfaces, it tends to split up into hydrogen atoms (H), which can then diffuse through metals and polymer seals. In the best case, it will leak out within months/years. In the worst case, it will change the crystal lattice and cause material failure. In particular, rare-earth magnents tend to crumble if exposed to hydrogen gas; that's something you really don't want inside a hard disk casing.
"So-called" is a literal translation of Dutch "zogenaamd". The Dutch version doesn't suggest that the speaker disagrees with whatever follows. The author meant to introduce a name that may not be familiar to the reader.
"AFAICT no standard mandates that. I would place the burden of cleaning the memory on the *initialization* of the new application."
Common sense mandates that a multi-user system separates users and processes from each other. If I log off from a workstation, the next user should not be able to do screen captures (potentially confidential documents, emails with passwords) using software that exploits this "feature".
How do you get the temperature sensing cable in the freezer without interfering with the insulation? I have a fridge/freezer with A+++ energy rating and I suspect that there is vacuum insulation in there that doesn't like me drilling holes.
"The question is, are today's diesels especially bad, or are they better than the previous generation â" just not better enough for someone somewhere?"
As the other poster explained: they are worse for NOx unless they have proper exhaust treatment. For VOC and soot, they are much better. For ultrafine particles (PM10/PM2.5), it's unclear to me. Certainly, ultrafine patriculates are a bigger fraction of the soot emission, but whether PM10 itself has increased or not, we don't hear so much.
Let's do a calculation. A quick google tells me that the EPA limit for air quality is 100 ug/m3. A car that emits 1 g/km can turn 10,000 m3 per km of air into an unhealthy level. A major road that carries 1000 bad diesel cars per hour could pollute all air in ~100 m radius around the road over the course of the morning rush hour. Ouch. If you have a lot of roads and traffic all day long, that's a big contribution.
What would be physical mechanism behind the change in the relation between BAC and breath alcohol? Breath alcohol level should depend only on the temperature and the alcohol/water ratio in the lungs, which should be very close to the BAC.
"Settings > iTunes and App Store > Password Settings"
This sounds like the beginning of THHGTTG, where the guy's house is bulldozed because he didn't know that he should have checked in the city hall to find out that this was planned.
The default should be to protect the user against them shooting in their feet and to make them go out of their way to disable the protection. Don't expect them to oversee and remember all potential consequences of typing in their cc number.
"at home, where already for significant time the image and audio quality is more pleasant than in most public theaters,"
What are 'most public theaters' like where you live? I saw the trailer in a local theater and the deep rumbles made me shake in my seat. Can you do that at home?
And good for you that you can afford it. For me it's a matter of economy. A home theater that can compete with a cinema would cost me in the upper four digits (EUR), to be depreciated over 6 years. On top of that the bluray discs themselves and the value of the home theater room space. Rental prices here are about 14 E/m2/month (costs for home owners are a bit less), so a house with space for an extra 12 m2 home-theater room would cost you about 2 kE/yr to own. Even though I could afford it, it feels like a waste of money.
Oh and you shouldn't have close neighbors or family members that value quiet time...
Again, in your ideal world with well-educated voters that are willing to spend time on understanding how it works and how to protect their credentials, this would work. In practice, people only get to practice the procedure once every four years and people will forget their credentials and all either show up on the last minute, or their votes will get lost. Heck, even I forget the password to submit my tax forms basically every year because I only use it once a year, and then my account gets blocked after the third incorrect password entry. I really don't want to keep track of separate real and duress passwords (without explicitly labeling them as such, which defeats the purpose), leave alone cryptographic keys.
And how is that different from taking a selfie with your ballot before casting it?
There was actually a debate here in the Netherlands about ballot selfies and a lot of people wanted this to be explicitly forbidden. In the end it was allowed because you could discard the ballot after the selfie and ask for a fresh one.
Slashdot Mirror
"SoftNumber5My5trongB4seP@ssw0rd005"
And how many times do you typically have to enter such a 35-character password on a day?
Do you do anything else besides logging?
I once set up an ssh honeypot in a chroot jail (with noexec and hardly anything in /bin; this was in 2005, before VMs were easy to run) to see what would happen; login guest/guest. Surely someone logged in, but they didn't attempt anything once inside. Maybe they were going to come back, but I didn't wait for it.
Well, a business laptop of EUR 1000 doesn't really count as a cheap DIY solution. And my employer-supplied laptop always charges to 100% when docked, as far as I can tell. Corporate IT has blocked user access to BIOS/UEFI, so I don't know what it can do.
"a more powerfull laptop ... has a built in UPS"
I once tried running an old netbook as server (dns and files, not routing) with UPS. When the power outage came, half a year later, it shut off immediately. Moreover, it didn't boot on its own when the power came back. With the lud closed, it was always kind of hot.
Apparently, Li-ion batteries need to be discharged every now and then to keep their calibration. The charging hardware seemed to think that the battery was fully charged while it was really empty. I've seen this happen as well with another laptop and a tablet.
"[Belgium's] police has no clue where their potential terrorists live"
Are you suggesting that that is different from other countries?
"Keypass2 is a .Net rewrite that doesn't work well on ANY platform, and it's new format is not widely supported. The only decent feature that Keepass2 added was better multi-user support, which is pointless for most users anyway. Go with Keepass1."
As for the leading Android implementations, keepass2android is definitely better than keepassDroid. They use the same database format (kdbx). However, KPD does not black out its thumbnail in the recent-apps list, does not have the same features for auto-locking the database, and does not warn about clipboard snooping attacks. If someone grabs your phone, you're at more risk with KPD than with KP2A.
"Also, plastic clamshells tend to hold up okay when dropped"
All my laptops suffered from material fatigue in the case. Three times a crack on the right of the keyboard (from holding it with one hand), two with a severe crack on the back of the screen, near the hinges. I would welcome a small laptop (11-12 inch) that really lasts. Although among them were a 14-in Thinkpad T23 and a 14-in Dell Latitude, so it weren't just ultraportables.
Because the pressure of He inside is equal to the partial pressure of He inside.
Unless the pores in the balloon have diameters that are much larger than the mean free path length (about 50 nm at atmospheric pressure), the absolute pressure doesn't matter for the leak rate, only the partial pressure. I doubt that balloon rubber has pores that large, but it could be. Even in the likely case that the pores are small (<100 nm), the pore size may shrink as the balloon deflates, which will depress the leak rate more than what can be explained from the change in membrane thickness.
Disclosure: I am a vacuum engineer. If you don't believe it, then I suggest that you read up on the concepts of Knudsen number, Fick's law, and permeation.
I volunteered in a drug trial around 1995 or so. Back then, it paid NLG 100 per day, or EUR 70 corrected for inflation. When you're in college, that's a lot of money, especially since you can study your quantum mechanics at the same time. There was a guy who was participating in studies all the time.
It was a phase-2 trial though; the (benign) side effects were already known. Phase 1 and drugs with severe side effects paid better. And we were told what kind of medicine it was and what side effects to expect before signing.
In an inflated balloon, you have 1.05 bar of He on the inside and 0.000005 bar of He on the outside.
When the balloon is almost deflated, you have 1.00 bar of He on the inside and 0.000005 bar on the outside. So that would make the diffusion speed decrease by a whopping 5 percent.
Let me start with an appeal to authority: I actually get paid to do calculations on gas diffusion and pumping of hydrogen.
Depending on the materials of the walls of your helium-containing vessels, drawing a vacuum can take rather long. The point is that diffusive transport is driven by differences in partial pressures (or concentration if the gas is dissolved in a solid). The partial pressure of helium in the atmosphere is about 0.5 Pa; if you have a vessel with a porous wall with 100 kPa of helium (atmospheric pressure) on the inside, then helium will diffuse towards the volume with the lower partial pressure until both sides have the same partial pressure (i.e., 0.5 Pa). The same process will happen in the opposite direction for other gases (nitrogen, oxygen), but at a much slower speed. So at t=0, you have 100 kPa He (pure). After 1 year, you have (for example) 50 kPa He and 0.01 Pa nitrogen. After ten million years, you have 0.5 Pa He and close to 100 kPa nitrogen.
Just imagine that you have a box with a small hole and lot of fruit flies on the inside. Place this box next to a stable where there are lots of big flies. The fruit flies will gradually disappear from the box, but not because they are pushing each other or because the fat flies (that don't fit through the hole) are pushing them out.
Here are the basics of diffusion: https://en.wikipedia.org/wiki/... .
For helium, diffusion speed is proportional to the difference in partial pressures on either side of the wall. For hydrogen, it's more complicated because the hydrogen molecules first need to dissociate before they can permeate through metals; it turns out that the speed of diffusion is driven by the difference in square roots of the partial pressure of hydrogen on either side.
If you have had hands-on experience with these things: do you have any idea how they handle pressure differences? Hard disk casings typically have flat sides, which are not ideal for handling pressure. In a pressurized airplane, you can have 0.3 bar pressire drop, which will exert about 30 kg of force on the walls. It's worse if they are shipped as unpressurozed cargo. So, the walls must be thicker than with a conventiomal HD, which conflicts with the goal of increasing the number of platters.
"In order for them to leak other particles need to diffuse into the drive to replace the missing atoms, it's not going to leak itself into a vacuum,"
Actually, you will draw a vacuum, provided that you wait long enough. In balloons, the process slows down not because the pressure difference decreases, but because the latex rubber layer gets thicker as the balloon shrinks.
What matters for the hydrodynamics (drag forces, lift forces on the head) is not directly the size of the molecule, but the molecular mass (related to densitiy of the gas) and the dynamic viscosity (related to both molecular mass and molecular size). The size of the molecule or atom is in any case vanishingly small compared to the distance between the head and the platter. The dynamic viscosities of a few gases at room temperature are: helium is 19 micro-Pa s, air 18 uPa s, and hydrogen 9 uPa s. The molecular masses (proportional to density) are 4, 29, and 2, respectively; this is where helium wins, but hydrogen is better both in molecular mass and viscosity.
The real reason for not using hydrogen gas is that hydrogen (H2) is reactive; at surfaces, it tends to split up into hydrogen atoms (H), which can then diffuse through metals and polymer seals. In the best case, it will leak out within months/years. In the worst case, it will change the crystal lattice and cause material failure. In particular, rare-earth magnents tend to crumble if exposed to hydrogen gas; that's something you really don't want inside a hard disk casing.
"So-called" is a literal translation of Dutch "zogenaamd". The Dutch version doesn't suggest that the speaker disagrees with whatever follows. The author meant to introduce a name that may not be familiar to the reader.
"AFAICT no standard mandates that. I would place the burden of cleaning the memory on the *initialization* of the new application."
Common sense mandates that a multi-user system separates users and processes from each other. If I log off from a workstation, the next user should not be able to do screen captures (potentially confidential documents, emails with passwords) using software that exploits this "feature".
"an ESP8266 in each reporting the temperatures"
How do you get the temperature sensing cable in the freezer without interfering with the insulation? I have a fridge/freezer with A+++ energy rating and I suspect that there is vacuum insulation in there that doesn't like me drilling holes.
"The question is, are today's diesels especially bad, or are they better than the previous generation â" just not better enough for someone somewhere?"
As the other poster explained: they are worse for NOx unless they have proper exhaust treatment. For VOC and soot, they are much better. For ultrafine particles (PM10/PM2.5), it's unclear to me. Certainly, ultrafine patriculates are a bigger fraction of the soot emission, but whether PM10 itself has increased or not, we don't hear so much.
Let's do a calculation. A quick google tells me that the EPA limit for air quality is 100 ug/m3. A car that emits 1 g/km can turn 10,000 m3 per km of air into an unhealthy level. A major road that carries 1000 bad diesel cars per hour could pollute all air in ~100 m radius around the road over the course of the morning rush hour. Ouch. If you have a lot of roads and traffic all day long, that's a big contribution.
What would be physical mechanism behind the change in the relation between BAC and breath alcohol? Breath alcohol level should depend only on the temperature and the alcohol/water ratio in the lungs, which should be very close to the BAC.
"Settings > iTunes and App Store > Password Settings"
This sounds like the beginning of THHGTTG, where the guy's house is bulldozed because he didn't know that he should have checked in the city hall to find out that this was planned.
The default should be to protect the user against them shooting in their feet and to make them go out of their way to disable the protection. Don't expect them to oversee and remember all potential consequences of typing in their cc number.
"at home, where already for significant time the image and audio quality is more pleasant than in most public theaters,"
What are 'most public theaters' like where you live? I saw the trailer in a local theater and the deep rumbles made me shake in my seat. Can you do that at home?
And good for you that you can afford it. For me it's a matter of economy. A home theater that can compete with a cinema would cost me in the upper four digits (EUR), to be depreciated over 6 years. On top of that the bluray discs themselves and the value of the home theater room space. Rental prices here are about 14 E/m2/month (costs for home owners are a bit less), so a house with space for an extra 12 m2 home-theater room would cost you about 2 kE/yr to own. Even though I could afford it, it feels like a waste of money.
Oh and you shouldn't have close neighbors or family members that value quiet time...
Tut, tut, calm down and take your meds.
Again, in your ideal world with well-educated voters that are willing to spend time on understanding how it works and how to protect their credentials, this would work. In practice, people only get to practice the procedure once every four years and people will forget their credentials and all either show up on the last minute, or their votes will get lost. Heck, even I forget the password to submit my tax forms basically every year because I only use it once a year, and then my account gets blocked after the third incorrect password entry. I really don't want to keep track of separate real and duress passwords (without explicitly labeling them as such, which defeats the purpose), leave alone cryptographic keys.
There was actually a debate here in the Netherlands about ballot selfies and a lot of people wanted this to be explicitly forbidden. In the end it was allowed because you could discard the ballot after the selfie and ask for a fresh one.