But artifacting is not neccesarily the fault of MPEG-2.
Artifacting occurs in any lossless compression scheme, and usually its more noticable in video becasue the compression is done in cells.
If the decompressed cells don't end up very similar at the edges we see the cell boundaries.
Artifacting occurs when there is not enough data to give a good enough picture, i.e. the compression has had to work very hard and you've lost more than the ideal.
This was terrible in MPEG-1 because it was a fixed, and low data rate.
In MPEG-2 the data rate is variable so that sections needing more data to form an acceptable final image can have it, without wasting space on sections that don't.
MPEG and DivX schemes are also temporaly compressed, so each frame may not be a full frame, but just changes from the last. Other formats like DV don't do this, but they need more storage.
MPEG-2 has the finesse that it can provide data about future frames as well, this allows the data rate to peak above the maximum briefly so things like rapid movement and scene cuts don't artifact.
Now another problem of artifacting comes into play - if your codec doesn't have the speed or memory to properly store this partial frames, then it gets really messy - this can happen if the DVD tries to pump in too much data to a cheap DVD player.
In all cases good production of the DVD master NON-REALTIME can aliviate much of these problems, by setting key frames and shaping the data rates. This is a highly skilled job, and involves judging acceptable visual quality, what datarates you think consumer DVD players will cope with, and how much space do you leave on the DVD for the 'extra features' people have come to expect. The last is an important point and now some producers are producing editions re-mastered at higher data rates with no extra cruft.
Now any ripper codec cannot tune itself any better than its source - you can't easily recognise the keyframes, nor are most rippers capable of effectively creating 'look ahead' frames - rippers tend to go for the quick-and-dirty-one-size-fits-all approach. You can also see this on cheap DVDs that have been bulk transfered, especially a lot of old budget films.
In the future I expect that high end formats will drop temporal compression and just use spatial compression within the fram like DV and M-JPEG and BetaCam Digital - once we have a media that can store the data.
Then tell me if you think the Slashdot editorial was wrong.
That was my point, not an opinion of which is the best news site.
I am not saying I believe The Register because it's gospel, yes its frequently opinionated but I like that, but in this case it is not an opinion piece, and has more block qoutes than Wired article.
In this case I believe Slashdot is innacurate, the fact it's opinionated is a given!!
No one would rate Slashdot as a news source either.
My point was that the editorial was IMHO not just opinionated, but plain wrong
Did you follow the link I gave? I based my opinion on the direct qoutes from M$ staff in the article. Did you follow the original link? There's more real detail in The Register article
Now granted John Lettice may have picked those qoutes with care, but I'm a regular reader and he is generally fair. I would say Paul Boutin at Wired has been far more selective in his qouting and it seems far more scewed, but no where near as bad as the angle the editorial takes.
You tend to get a more slanted opinion on The Register from Andrew Orwlinski or Thomas C Greene - but the advantage of having staffers is you get to know thier strengths and judge thier work.
Whereas on Slashdot anyone can say it loud confident and frequently wrong.
If you're going to contribute nothing but pithy (and frankly hypocritical due to the very strong anti M$ slant in Slashdot in general) then at least do me the favour of reading the links.
And please refrain from adding to the noise level.
They are actually giving up on trying to secure older products.
And they are stating that for new security fixes on current products they are now putting security as a higher priority than not breaking the apps.
So rather than provide the security turned off, in the hope that some MCSE will turn it one once the app has been patched, the security is on even if the app breaks.
Now, regardless of the anti M$ feelings, this has got to be a good approach.
Yes you can read it as "Hear comes DRM, suck it down" or you can read it as "Secure by default really does matter, becasue we know 95% of users never change from the default settings" - the latter approach is taken by Suse in 8.1 and I don't see/. attacking them
[A shady scene in a seedy downtown bar] Rosen : "And last week we introduced CD's that will hardly play in anything and yet still the sheep buy them" Valenti : "Heck we released DVD's that self destruct in 8 hours, and they're 'renting' those" All : guffaw, guffaw
[exunt omnes]
And the most fun to be had with an Adaptive Optics system is if it uses a laser generated guide star.
Then you can chuck a frisbee like object through the beam and watch it get zapped:)
Did I say this was seriously frowned on, I think I should:)
Adaptive Optics in a Nutshell:
1) You use a single point source as a reference. 2) You know the aberation caused by the atmosphere will spread the point image when you receive it. 3) You know that as your source is a point source, then the resultant spread in your image is entirely due to aberation, so use the image to calculate the Point Spread Function 4) Using the PSF apply a correction to the light path by altering something in the imaging system, usually a mirror. 5) Repeat several hundred times a second
Of course the great side effect is this also removes distortion caused by the imaging system itself, allowing you to use bigger mirrors with a lower tolerance than you otherwise might be able to do.
Originally point sources were strong and predictable stars in the field of view that you wanted - hence the term 'guide stars'
With a laser generated guide star you project a spot onto the upper surface of the atmosphere with a powerful laser of an appropriate frequency - close to your obsering frequency, but far enough out that you don't effect the observation. The subtlety here is to account for the fact that the point source will be spread twice, once on the way up and once on the way down.
Anyone working in AO I apologise to for the somewhat oversimplification - follow the links in the parent to better details if your interest is fired.
From my days doing Earth Observation Science (EOS) I recall that a lot of satellite imaging, whether astronomical or remote sensing, seemed to follow a de-facto standard of a 512 x 512 x 8bit image tile per channel on the instrument.
GIFs were often used because it is a very stable way of doing lossless compression at 8bit, stable as in almost any image program can read them.
This is not the case with TIFFs as there are a number of variants and options in the file format.
TIFFs are however a better medium for storage of composite images, either spatially or spectorally (montages or multichannel pseudo colour in english).
Due to its general lack of use as a data storage format most of the tools I used/wrote to proccess image data files generally did not have JPEG support or other common 'display' options as the file is regarded as data, not an image - its a subtle difference but explains the mindset.
When I published stuff on the web I'd run our raw large images through Photoshop to get pleasing images but compact file sizes.
It may not have occured for them to do this, and anyway they may regard this as publishing data for other interested parties to download and process themselves.
Seriously they chose to put large size images linked from a press release - I mean they're not even deep links, nor is this one near the bottom of the page. Its probably one of the most likely links everyone will click on if they read the story. Its linked from a press release they expect this too be read, its not like we slashdotted a tiny departmental server.
Does moving it from a 2 click (slashdot story - press release image - gif) to 1 click[1] (slashdot story) really justify a personal broadside against the editorial integerity of one the slashdot team?
Comment on the fact that maybe they should be warned so they remove the high res links until the slashdotting is over, maybe comment on the poor web design approach of the academic team involved, any number of these are valid responses to this story.
Your response adds nothing to the story, nor is what I would expect from someone (judging by you name and email) who is experienced at proffesionally critiquing and assess others work in thier career. Or do peer reviews in Academia these days descend to personal attacks, unwarranted sarcasm and flamewars too?
It seems a strange contrast to your statement about stupidity on the site, did you mean the content of the site or the quality and relevance of the posts on it?
[1]1-Click is of course patented by Amazon, so we must be careful...
'If I stand on a hill in a storm with copper armour and a sword held up at arms length shouting "All the gods are bastards", will I get hit by lightning?' (With apologies to PTerry)
Seriously - lets not retread the same old stuff on Slashdot that most of us could write code to generate the resulting opinions and flamewares (Linux vs M$ / P2P vs RIAA / SCSI vs IDE / MAC vs PC)
The best discusions I've seen here are where we get a good spread of opion, those are interesting and challenging.
Anyway once you've invested in KAP gear, there is little running cost, your Cessna 142 is going to be around 100UKP/150USD an hour to run, and you have the risk of leaning out of the plane.
And at least in the UK you can't fly a plane at a low level (sub 250feet) and higher in some areas, but you can fly a kite.
Serious (commercial) users tend to use large lift ballons as they are more stable and predicatble - I've seen a great book of pictures by a UK company that does this with a DV Cam and a Hasslebad medium format using a helium ballon - all run from the back of LandRover as studio/transport/ground teather. SkyCam I think? Sorry can't find it now on amazon.
I'd like to see a plane station itself 60 feet off the battlements of an historic country house to get a birds eye view - ballons and kites can do that, only a rotary wing aircraft can and they probably won't fly that close, and cost uber amounts of dollars per hour!
Not if you get a good quality proper kite, maybe if you buy from Toys 'R' Us. A Revolution 1.5 or FlexiFoil 10 is around 200UKP/300USD - course these arn't great for KAP, but its what I fly currently and serves to show that kiting is not as cheap as you might expect (cos you go and get kites for different conditions and challanges) but it is serious fun:)
New Digital Camera
And thats why people use simple 35mm autowinders, or cheapo all in one CMOS digitals to start with.
Crashing it into the ground on your first try
And thats why you practise until you become and expereinced kite pilot before you take up KAP to extend the enjoyment of your hobby.
Seriously you'll find the kite is probably the most expensive part of the rig.
Sadly I expect the practical issues of having your house festooned with other peoples dishes, and the normal paranoia over 'radiation' we see over phone masts, and the fact your link would be dependant on there not being a power outage at you neighbours up the road, and who exactly pays for the electricity for those other dishes.
Yes I think what you suggest could work well in sparse communities where people are used to being more self-sufficient and looking out for each other.
I just don't think its a practical thing in a dense population, there are better solutions for that.
Thanks for that, not noticed that. But it occurs to me that you might need a reasonable distance to harness this (sorry I've not looked at the patent) and you would need energetic particles.
You are still going to need a shield system, and it may be bigger if they are more energetic.
The beauty of the thermal route is that the shielding performs several roles as shield, thermal mass and support for the thermocouple matrix - and its that that makes the so suitable for compact applications.
But the technology you refer to would be much more suitable for larger, high power systems.
Once the radiation has dropped below a usable level then there is no radioactive risk if you have an isotope whos decay products are of a lower activity.
How does the danger of atomic batteries in the local landfill compare to these other heavy metal toxins?
I don't know, because I don't know the materials they are trying. However there will be negligable risk from radition as already noted, but you do need to consider the chemcial/biological risk.
Remember a material can be dangerous because of its radiation effects, chemical effects and biological effects
Radon gas is radioactive and therefore dangerous to health, but it won't cause chemical burns, or poison you
Bleach will cause burns due to being a strong oxidiser, but is not radioactive, nor will it poison you.
Cyanide will poison you by preferentially binding to you hemoglobin and suffocating you as your blood can no longer carry oxygen to your tissues, but will not burn, nor is it radioactive.
Please remember that radioactivity is nothing special, you need to assess all risks of the material - I just didn't want to extend an already long post by these clarifications.
I thought that since space was a near vacuum it was very difficult to cool things, as the cooling process needs to transfer the heat energy to something else
It does - infra red radiation. You're thinking of conduction where 'heat energy' is transfered directly to another mass, or convection where the 'heat energy' is moved away by a fluid.
A vacuum is a near perfect insulator.
Only for conduction - thats why they silver the inside of thermos flasks.
In space a large finned radiator pointing towards deep space is a quite efficient method of dissapting heat.
OK - How Atomic Batteries Work and Medical Physics 101:)
Medical Physics
The damage done to human tissue is a function (~linear) of the amount of energy deposited by the radiation into the tissue.
This is a function itself of:
1) The amount of energy depositied by the radiation per unit of path length.
2) The length of the path in the body.
Also of interest in practical situations is this also applies to shielding i.e. if the shielding is such that the energy is enirely deposited in the shield materiel then the radition is fully shielded. If not then you have attenuated the radiation.
On one hand massive particles like Alpha Particles are 'safer' because they deposit energy quickly (they interact fairly strongly with matter), so can be stopped by very small masses like paper/foil/skin epidermis. On the other hand high energy Alpha Particles can be very dangerous if not shielded because they can carry a lot of energy into the body due to thier mass, and deposit it there as the tissue stops the particle.
At the other extreme Gamma Radiation is 'bad' because it doesn't lose energy very easily (becasue they don't interact as strongly with matter) so they cannot easily be shielded, but will at least not deposit the whole of the energy in the tissue but pass through it. Unfortunatley of course gamma radiation is highly energetic so it can still deposit a lot of energy.
So the risk of medical damage from a radioactive source is function of
1) The strength of the emmission
2) The type of emmission
3) The amount of shielding between the source and you
It is not just the radition type.
As already stated the biggest risk is when radioactive substances are ingested such that they stay in the body for some time, as this increase the energy depositied into the tissue - alpha emission is particularly bad here because it will deposit the whole of the energy into the surrounding tissue.
In this instance you may well find that a low energy beta source is a better choice, because with a low energy alpha source the raditation may not even make it out of the source's casing.
Atomic Batteries
For the interested 'atomic' batteries generaly work by using a radioactive source to heat a shield material around it. This heat can then be turned into electricity by putting a thermocouple matrix in the shield material, with the hot junction in the material, and the cold junction outside.
Now in this case we need a lot of energy in the shield material, but enough to get out of the sources casing, so low energy beta is good here.
It is safe, because the whole point of the design is that the radiation is shielded, thats how you recover the energy into electricty. You will get very very little external radiation from a well designed atomic battery.
This is not new technology, deep space probes have been using them for years because solar cells would be useless in the outer solar system
The characteristics of this sort of power generation is that it is physically small, long lasting but low current. This is ideal for portable devices, but not usable really for transport or power devices.
Practically you would probably need another battery like LiIon such that the LiIon cell is trickle charged all the time, but can supply surges of power.
This would be great in a cellphone where the LiIon battery would supply the high power needed for transmiting during the calls, and the atomic battery would supply enough to charge the LiIon and do standby - phone not got enough charge, just leave it for an hour. Conceptually you may never need to charge the phone, or change the battery, it could be fitted for life in the phone.
The challenge is finding the right materials and making it mass producable. On space probes its easy because you can cool the cold junction in the vacuum of space and make it efficient, plus you don't really care about the cost or making 1000's of them a week.
Yep - have you seen the plans for 4G mobile phone technology?
The problem is the processing over head to run a phased array is a fair bit in the first place, but probably a solved problem these days.
Then you add in the fact that you're running multiplexing so the array is switching beams several times a second if not faster. Thats going to add to the processing.
Then you add in the fact that to do mobile coms you have to have some feedback monitoring so that you can calibrate the offset you need to stear the beam next time that timeslot is used because you're aiming at a moving target.
The first 2 points aren't that hard, and have been done in radar systems for a while.
The last is going to be very fun trying to get a phased array cell site to track 200 calls at once - I just want my hands on the computer that can do it.
From what I see some in my industry are talking about going straight to 4G technology as the 3G(CDMA/UMTS) doesn't give much over the existing 2G(GSM) when extended to '2.5'G (GPRS/HSSCD/EDGE). Judging by the rate that GSM technologies penetrated maybe in 10 years we might start seeing 4G style networks where the beam is actively steared at your recieveing equipment, rather than just broadcast in your sector.
I would guess that of more interest to the seismologists is the record of the information preceding the quake.
It's this that they are monitoring looking for signs of stress and movement to try and predict sesmic events, and use the seismic data for other science.
If the event is local enough to disrupt the link, then you have to fix it, same as if it brought down the poles for normal cable links.
Also don't assume every seismograph is in an active area[1] as we have plenty of the instruments over here in the UK and we're not exactly known for our 'big ones'. We had a 10second ~4 in the Midlands the other month that was big enough to wake me up and go "WTF?" - but that was our biggest in 10 years.
Of real interest are the traces of distant seismic events and thier echos because analysis of the traces from several global stations can reveal a lot about the internal structure of the Earth, as the various types of seismic waves travel/refract/reflect differently in different mediums. Correlate enough and you can measure density of the rock and magma, and place the interfaces fairly accurately.
And your last comment made me spew coffee on the keyboard - thanks!!
[1] Sorry my US geography ain't the best, for all I know San Clemente Island could be volcanic, which would somewhat ruin my argument
Sadly this is not going to be very useful in general.
Why?
Think it through - this will need to have a discreet dish at each end of the link.
Fine at your house, put it on the roof or a better positioned pole.
But at the Exchange end you will need one for every link. Now if you have 200 customers needing this can you imagine the physical mounting problem at the Exchange.
So in the end it will help (maybe) at the fringes of the phone network where physically connecting is not cost effective or practical (Scottish Highlands in the UK, Outback in Australia etc) but its not going to be available for the masses.
Now I have had a wireless telephone system here in the UK (Ionica - any of the other 64,000 users out there - most of us seemed to be techs?) But that used a low power direction dish at my end, and a much higher power single wideangle array at the exchange end.
Paragraph 1 is an inaccurate[1] and personal attack on the previous poster - no insight here.
Paragraph 2 is the usual bleating of 'how did my email get out' - no insight here.
Paragraph 3 is a BGO, Blinding Glimpse of the Obvious - no insight here.
Paragraph 4 is a plain and simple personal attack - no insight here
====
[1] Why Inaccurate?
1) Because enabling a program to run without using its CD as a key does not AUTOMATICALLY mean the poster does not own the original.
2) Because while the use of the no-cd crack for any reason may be illeagal under the DMCA in the US, elsewhere it is not, and will be decided on intent.
3) The poster's family is not at any legal risk - in most juristrictions (Not US due to DMCA) this is a CIVIL not a CRIMINAL risk, no-one is going to chase you for a few bucks because they will have to pay for the case, the state will not. Even in a juristriction where this is a crminial offence it will almost certainly not be prosecuted by the state as it will not be in the pbulic interest.
Additionally they can only chase the poster, not thier family. Why be personal and bring thier family into the argument. Not surely because they took the trouble to explain they'd used the no-cd crack to protect the original cd's when his kids played with them? If thats the true explanation then that is perfectly morally and ethically defensible thing to do with something you own that in certain juristrictions is being criminilized by poor legislation
Yeah - I mean a commodity OEM hard drive thats shipped around in a school bag, left under a desk, left in the car, connected and reconnected is going to last so much longer than the same drive nicely tucked into a system case.
CD backup is the EXCELLENT idea, the drive will just be an expensive way of blowing dollars that could buy thousands of CD-R blanks.
Heres an even better idea - burn them as audio CDs, and then you can *gasp* even recover your data without a PC!!!!
Slashdot Mirror
But artifacting is not neccesarily the fault of MPEG-2. Artifacting occurs in any lossless compression scheme, and usually its more noticable in video becasue the compression is done in cells. If the decompressed cells don't end up very similar at the edges we see the cell boundaries. Artifacting occurs when there is not enough data to give a good enough picture, i.e. the compression has had to work very hard and you've lost more than the ideal. This was terrible in MPEG-1 because it was a fixed, and low data rate. In MPEG-2 the data rate is variable so that sections needing more data to form an acceptable final image can have it, without wasting space on sections that don't. MPEG and DivX schemes are also temporaly compressed, so each frame may not be a full frame, but just changes from the last. Other formats like DV don't do this, but they need more storage. MPEG-2 has the finesse that it can provide data about future frames as well, this allows the data rate to peak above the maximum briefly so things like rapid movement and scene cuts don't artifact. Now another problem of artifacting comes into play - if your codec doesn't have the speed or memory to properly store this partial frames, then it gets really messy - this can happen if the DVD tries to pump in too much data to a cheap DVD player. In all cases good production of the DVD master NON-REALTIME can aliviate much of these problems, by setting key frames and shaping the data rates. This is a highly skilled job, and involves judging acceptable visual quality, what datarates you think consumer DVD players will cope with, and how much space do you leave on the DVD for the 'extra features' people have come to expect. The last is an important point and now some producers are producing editions re-mastered at higher data rates with no extra cruft. Now any ripper codec cannot tune itself any better than its source - you can't easily recognise the keyframes, nor are most rippers capable of effectively creating 'look ahead' frames - rippers tend to go for the quick-and-dirty-one-size-fits-all approach. You can also see this on cheap DVDs that have been bulk transfered, especially a lot of old budget films. In the future I expect that high end formats will drop temporal compression and just use spatial compression within the fram like DV and M-JPEG and BetaCam Digital - once we have a media that can store the data.
NOT The Register editorial for chrissake - The Slashdot one
:)
Does anyone around here actually read the links?
Sorry - forgot where I was for a moment, silly question
Do me a favour - Read The Links - both of them.
Then tell me if you think the Slashdot editorial was wrong.
That was my point, not an opinion of which is the best news site.
I am not saying I believe The Register because it's gospel, yes its frequently opinionated but I like that, but in this case it is not an opinion piece, and has more block qoutes than Wired article.
In this case I believe Slashdot is innacurate, the fact it's opinionated is a given!!
No one would rate Slashdot as a news source either.
My point was that the editorial was IMHO not just opinionated, but plain wrong
Did you follow the link I gave? I based my opinion on the direct qoutes from M$ staff in the article. Did you follow the original link? There's more real detail in The Register article
Now granted John Lettice may have picked those qoutes with care, but I'm a regular reader and he is generally fair. I would say Paul Boutin at Wired has been far more selective in his qouting and it seems far more scewed, but no where near as bad as the angle the editorial takes.
You tend to get a more slanted opinion on The Register from Andrew Orwlinski or Thomas C Greene - but the advantage of having staffers is you get to know thier strengths and judge thier work.
Whereas on Slashdot anyone can say it loud confident and frequently wrong.
If you're going to contribute nothing but pithy (and frankly hypocritical due to the very strong anti M$ slant in Slashdot in general) then at least do me the favour of reading the links.
And please refrain from adding to the noise level.
I read the same story at The Register
/. attacking them
The editiorial is innacurate and opinionated.
They are actually giving up on trying to secure older products.
And they are stating that for new security fixes on current products they are now putting security as a higher priority than not breaking the apps.
So rather than provide the security turned off, in the hope that some MCSE will turn it one once the app has been patched, the security is on even if the app breaks.
Now, regardless of the anti M$ feelings, this has got to be a good approach.
Yes you can read it as "Hear comes DRM, suck it down" or you can read it as "Secure by default really does matter, becasue we know 95% of users never change from the default settings" - the latter approach is taken by Suse in 8.1 and I don't see
Hey its thier entertainment, not ours...
[A shady scene in a seedy downtown bar]
Rosen : "And last week we introduced CD's that will hardly play in anything and yet still the sheep buy them"
Valenti : "Heck we released DVD's that self destruct in 8 hours, and they're 'renting' those"
All : guffaw, guffaw
[exunt omnes]
And the most fun to be had with an Adaptive Optics system is if it uses a laser generated guide star.
:)
:)
Then you can chuck a frisbee like object through the beam and watch it get zapped
Did I say this was seriously frowned on, I think I should
Adaptive Optics in a Nutshell:
1) You use a single point source as a reference.
2) You know the aberation caused by the atmosphere will spread the point image when you receive it.
3) You know that as your source is a point source, then the resultant spread in your image is entirely due to aberation, so use the image to calculate the Point Spread Function
4) Using the PSF apply a correction to the light path by altering something in the imaging system, usually a mirror.
5) Repeat several hundred times a second
Of course the great side effect is this also removes distortion caused by the imaging system itself, allowing you to use bigger mirrors with a lower tolerance than you otherwise might be able to do.
Originally point sources were strong and predictable stars in the field of view that you wanted - hence the term 'guide stars'
With a laser generated guide star you project a spot onto the upper surface of the atmosphere with a powerful laser of an appropriate frequency - close to your obsering frequency, but far enough out that you don't effect the observation. The subtlety here is to account for the fact that the point source will be spread twice, once on the way up and once on the way down.
Anyone working in AO I apologise to for the somewhat oversimplification - follow the links in the parent to better details if your interest is fired.
From my days doing Earth Observation Science (EOS) I recall that a lot of satellite imaging, whether astronomical or remote sensing, seemed to follow a de-facto standard of a 512 x 512 x 8bit image tile per channel on the instrument.
GIFs were often used because it is a very stable way of doing lossless compression at 8bit, stable as in almost any image program can read them.
This is not the case with TIFFs as there are a number of variants and options in the file format.
TIFFs are however a better medium for storage of composite images, either spatially or spectorally (montages or multichannel pseudo colour in english).
Due to its general lack of use as a data storage format most of the tools I used/wrote to proccess image data files generally did not have JPEG support or other common 'display' options as the file is regarded as data, not an image - its a subtle difference but explains the mindset.
When I published stuff on the web I'd run our raw large images through Photoshop to get pleasing images but compact file sizes.
It may not have occured for them to do this, and anyway they may regard this as publishing data for other interested parties to download and process themselves.
And this is Michael's fault how?
Seriously they chose to put large size images linked from a press release - I mean they're not even deep links, nor is this one near the bottom of the page. Its probably one of the most likely links everyone will click on if they read the story. Its linked from a press release they expect this too be read, its not like we slashdotted a tiny departmental server.
Does moving it from a 2 click (slashdot story - press release image - gif) to 1 click[1] (slashdot story) really justify a personal broadside against the editorial integerity of one the slashdot team?
Comment on the fact that maybe they should be warned so they remove the high res links until the slashdotting is over, maybe comment on the poor web design approach of the academic team involved, any number of these are valid responses to this story.
Your response adds nothing to the story, nor is what I would expect from someone (judging by you name and email) who is experienced at proffesionally critiquing and assess others work in thier career. Or do peer reviews in Academia these days descend to personal attacks, unwarranted sarcasm and flamewars too?
It seems a strange contrast to your statement about stupidity on the site, did you mean the content of the site or the quality and relevance of the posts on it?
[1]1-Click is of course patented by Amazon, so we must be careful...
And the ill-fated CLUSTER mission that we lost on the first Arianne 5 launch
Don't connect your computer to a phoneline/DSL/cable modem
:-)
Oh please don't try and convince me that wireless is more secure!
Or that IR is a practical alternative...
Or that you won't get mugged carrying the CD-Rs between home and office for you sneaknernet...
'If I stand on a hill in a storm with copper armour and a sword held up at arms length shouting "All the gods are bastards", will I get hit by lightning?'
(With apologies to PTerry)
Seriously - lets not retread the same old stuff on Slashdot that most of us could write code to generate the resulting opinions and flamewares (Linux vs M$ / P2P vs RIAA / SCSI vs IDE / MAC vs PC)
The best discusions I've seen here are where we get a good spread of opion, those are interesting and challenging.
Oh wait, I forgot where I was...
Thats why most people don't use digital.
Anyway once you've invested in KAP gear, there is little running cost, your Cessna 142 is going to be around 100UKP/150USD an hour to run, and you have the risk of leaning out of the plane.
And at least in the UK you can't fly a plane at a low level (sub 250feet) and higher in some areas, but you can fly a kite.
Serious (commercial) users tend to use large lift ballons as they are more stable and predicatble - I've seen a great book of pictures by a UK company that does this with a DV Cam and a Hasslebad medium format using a helium ballon - all run from the back of LandRover as studio/transport/ground teather. SkyCam I think? Sorry can't find it now on amazon.
I'd like to see a plane station itself 60 feet off the battlements of an historic country house to get a birds eye view - ballons and kites can do that, only a rotary wing aircraft can and they probably won't fly that close, and cost uber amounts of dollars per hour!
And you can see how much from that?
Seriously, the goals are different, rocketters want to get pictures from as high as possible, KAPers generaly want to get a usable aerial photograph.
I've been involved in both, and RCplanes and Ballons - the goals and challeneges of each are different but just as much fun.
And FYI there are people who fly single line kites on 'deep sky reels' at 4 miles or so. Now thats pretty incredible.
Nice Kite: $100
:)
Not if you get a good quality proper kite, maybe if you buy from Toys 'R' Us. A Revolution 1.5 or FlexiFoil 10 is around 200UKP/300USD - course these arn't great for KAP, but its what I fly currently and serves to show that kiting is not as cheap as you might expect (cos you go and get kites for different conditions and challanges) but it is serious fun
New Digital Camera
And thats why people use simple 35mm autowinders, or cheapo all in one CMOS digitals to start with.
Crashing it into the ground on your first try
And thats why you practise until you become and expereinced kite pilot before you take up KAP to extend the enjoyment of your hobby.
Seriously you'll find the kite is probably the most expensive part of the rig.
Sadly I expect the practical issues of having your house festooned with other peoples dishes, and the normal paranoia over 'radiation' we see over phone masts, and the fact your link would be dependant on there not being a power outage at you neighbours up the road, and who exactly pays for the electricity for those other dishes.
Yes I think what you suggest could work well in sparse communities where people are used to being more self-sufficient and looking out for each other.
I just don't think its a practical thing in a dense population, there are better solutions for that.
Thanks for that, not noticed that. But it occurs to me that you might need a reasonable distance to harness this (sorry I've not looked at the patent) and you would need energetic particles.
You are still going to need a shield system, and it may be bigger if they are more energetic.
The beauty of the thermal route is that the shielding performs several roles as shield, thermal mass and support for the thermocouple matrix - and its that that makes the so suitable for compact applications.
But the technology you refer to would be much more suitable for larger, high power systems.
Hence my point about right materials.
Once the radiation has dropped below a usable level then there is no radioactive risk if you have an isotope whos decay products are of a lower activity.
How does the danger of atomic batteries in the local landfill compare to these other heavy metal toxins?
I don't know, because I don't know the materials they are trying. However there will be negligable risk from radition as already noted, but you do need to consider the chemcial/biological risk.
Remember a material can be dangerous because of its radiation effects, chemical effects and biological effects
Radon gas is radioactive and therefore dangerous to health, but it won't cause chemical burns, or poison you
Bleach will cause burns due to being a strong oxidiser, but is not radioactive, nor will it poison you.
Cyanide will poison you by preferentially binding to you hemoglobin and suffocating you as your blood can no longer carry oxygen to your tissues, but will not burn, nor is it radioactive.
Please remember that radioactivity is nothing special, you need to assess all risks of the material - I just didn't want to extend an already long post by these clarifications.
I thought that since space was a near vacuum it was very difficult to cool things, as the cooling process needs to transfer the heat energy to something else
It does - infra red radiation. You're thinking of conduction where 'heat energy' is transfered directly to another mass, or convection where the 'heat energy' is moved away by a fluid.
A vacuum is a near perfect insulator. Only for conduction - thats why they silver the inside of thermos flasks.
In space a large finned radiator pointing towards deep space is a quite efficient method of dissapting heat.
OK - How Atomic Batteries Work and Medical Physics 101 :)
Medical Physics
The damage done to human tissue is a function (~linear) of the amount of energy deposited by the radiation into the tissue.
This is a function itself of:
1) The amount of energy depositied by the radiation per unit of path length.
2) The length of the path in the body.
Also of interest in practical situations is this also applies to shielding i.e. if the shielding is such that the energy is enirely deposited in the shield materiel then the radition is fully shielded. If not then you have attenuated the radiation.
On one hand massive particles like Alpha Particles are 'safer' because they deposit energy quickly (they interact fairly strongly with matter), so can be stopped by very small masses like paper/foil/skin epidermis. On the other hand high energy Alpha Particles can be very dangerous if not shielded because they can carry a lot of energy into the body due to thier mass, and deposit it there as the tissue stops the particle.
At the other extreme Gamma Radiation is 'bad' because it doesn't lose energy very easily (becasue they don't interact as strongly with matter) so they cannot easily be shielded, but will at least not deposit the whole of the energy in the tissue but pass through it. Unfortunatley of course gamma radiation is highly energetic so it can still deposit a lot of energy.
So the risk of medical damage from a radioactive source is function of
1) The strength of the emmission
2) The type of emmission
3) The amount of shielding between the source and you
It is not just the radition type.
As already stated the biggest risk is when radioactive substances are ingested such that they stay in the body for some time, as this increase the energy depositied into the tissue - alpha emission is particularly bad here because it will deposit the whole of the energy into the surrounding tissue.
In this instance you may well find that a low energy beta source is a better choice, because with a low energy alpha source the raditation may not even make it out of the source's casing.
Atomic Batteries
For the interested 'atomic' batteries generaly work by using a radioactive source to heat a shield material around it. This heat can then be turned into electricity by putting a thermocouple matrix in the shield material, with the hot junction in the material, and the cold junction outside.
Now in this case we need a lot of energy in the shield material, but enough to get out of the sources casing, so low energy beta is good here.
It is safe, because the whole point of the design is that the radiation is shielded, thats how you recover the energy into electricty. You will get very very little external radiation from a well designed atomic battery.
This is not new technology, deep space probes have been using them for years because solar cells would be useless in the outer solar system
The characteristics of this sort of power generation is that it is physically small, long lasting but low current. This is ideal for portable devices, but not usable really for transport or power devices.
Practically you would probably need another battery like LiIon such that the LiIon cell is trickle charged all the time, but can supply surges of power.
This would be great in a cellphone where the LiIon battery would supply the high power needed for transmiting during the calls, and the atomic battery would supply enough to charge the LiIon and do standby - phone not got enough charge, just leave it for an hour. Conceptually you may never need to charge the phone, or change the battery, it could be fitted for life in the phone.
The challenge is finding the right materials and making it mass producable. On space probes its easy because you can cool the cold junction in the vacuum of space and make it efficient, plus you don't really care about the cost or making 1000's of them a week.
Yep - have you seen the plans for 4G mobile phone technology?
The problem is the processing over head to run a phased array is a fair bit in the first place, but probably a solved problem these days.
Then you add in the fact that you're running multiplexing so the array is switching beams several times a second if not faster. Thats going to add to the processing.
Then you add in the fact that to do mobile coms you have to have some feedback monitoring so that you can calibrate the offset you need to stear the beam next time that timeslot is used because you're aiming at a moving target.
The first 2 points aren't that hard, and have been done in radar systems for a while.
The last is going to be very fun trying to get a phased array cell site to track 200 calls at once - I just want my hands on the computer that can do it.
From what I see some in my industry are talking about going straight to 4G technology as the 3G(CDMA/UMTS) doesn't give much over the existing 2G(GSM) when extended to '2.5'G (GPRS/HSSCD/EDGE). Judging by the rate that GSM technologies penetrated maybe in 10 years we might start seeing 4G style networks where the beam is actively steared at your recieveing equipment, rather than just broadcast in your sector.
Interesting times indeed.
I would guess that of more interest to the seismologists is the record of the information preceding the quake.
It's this that they are monitoring looking for signs of stress and movement to try and predict sesmic events, and use the seismic data for other science.
If the event is local enough to disrupt the link, then you have to fix it, same as if it brought down the poles for normal cable links.
Also don't assume every seismograph is in an active area[1] as we have plenty of the instruments over here in the UK and we're not exactly known for our 'big ones'.
We had a 10second ~4 in the Midlands the other month that was big enough to wake me up and go "WTF?" - but that was our biggest in 10 years.
Of real interest are the traces of distant seismic events and thier echos because analysis of the traces from several global stations can reveal a lot about the internal structure of the Earth, as the various types of seismic waves travel/refract/reflect differently in different mediums. Correlate enough and you can measure density of the rock and magma, and place the interfaces fairly accurately.
And your last comment made me spew coffee on the keyboard - thanks!!
[1] Sorry my US geography ain't the best, for all I know San Clemente Island could be volcanic, which would somewhat ruin my argument
Sadly this is not going to be very useful in general.
Why?
Think it through - this will need to have a discreet dish at each end of the link.
Fine at your house, put it on the roof or a better positioned pole.
But at the Exchange end you will need one for every link. Now if you have 200 customers needing this can you imagine the physical mounting problem at the Exchange.
So in the end it will help (maybe) at the fringes of the phone network where physically connecting is not cost effective or practical (Scottish Highlands in the UK, Outback in Australia etc) but its not going to be available for the masses.
Now I have had a wireless telephone system here in the UK (Ionica - any of the other 64,000 users out there - most of us seemed to be techs?) But that used a low power direction dish at my end, and a much higher power single wideangle array at the exchange end.
This is a 5????
Why - what is insightful here?
Paragraph 1 is an inaccurate[1] and personal attack on the previous poster - no insight here.
Paragraph 2 is the usual bleating of 'how did my email get out' - no insight here.
Paragraph 3 is a BGO, Blinding Glimpse of the Obvious - no insight here.
Paragraph 4 is a plain and simple personal attack - no insight here
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[1] Why Inaccurate?
1) Because enabling a program to run without using its CD as a key does not AUTOMATICALLY mean the poster does not own the original.
2) Because while the use of the no-cd crack for any reason may be illeagal under the DMCA in the US, elsewhere it is not, and will be decided on intent.
3) The poster's family is not at any legal risk - in most juristrictions (Not US due to DMCA) this is a CIVIL not a CRIMINAL risk, no-one is going to chase you for a few bucks because they will have to pay for the case, the state will not. Even in a juristriction where this is a crminial offence it will almost certainly not be prosecuted by the state as it will not be in the pbulic interest.
Additionally they can only chase the poster, not thier family. Why be personal and bring thier family into the argument. Not surely because they took the trouble to explain they'd used the no-cd crack to protect the original cd's when his kids played with them? If thats the true explanation then that is perfectly morally and ethically defensible thing to do with something you own that in certain juristrictions is being criminilized by poor legislation
Yeah - I mean a commodity OEM hard drive thats shipped around in a school bag, left under a desk, left in the car, connected and reconnected is going to last so much longer than the same drive nicely tucked into a system case. CD backup is the EXCELLENT idea, the drive will just be an expensive way of blowing dollars that could buy thousands of CD-R blanks. Heres an even better idea - burn them as audio CDs, and then you can *gasp* even recover your data without a PC!!!!