2490 posts • joined 24 Apr 2007
The speed of sound increases with the stiffness of the medium, and decreases with density. For an ideal gas stiffness depends on pressure, which depends of density and temperature. The net result is that the speed of sound increases with temperature. So low temperature leads to low speed of sound. High in the atmosphere, the temperature is low. However, at the altitude of satellites, things are probably more complicated, as ionizing radiation of the sun may heat molecules to 2,000 K or more (and ionize them, changing the properties of the dilute gas), depending on solar activity.
Some advanced reader (claim to) use IR light and the Doppler to detect moving blood under the skin. Those scanners are not fooled by these fake fingers. I gather some scanners even OKed photocopies of fingerprints
Re: NASA has found.....
Some sediments are actually deposited by wind. Plenty of that on Mars. Hydrocarbons would be interesting. Await yells of "There's oil in them there hills!!!", followed by a rush to get to the oil first
(and once found, wondering how on earth (Mars) they can ship it back to the nearest refinery)
I am given to wonder whether the odd results are real, or artefact of this new method. It would be really very cool if it works as flawlessly as claimed in this article. I will go and have a look at the actual paper to make up my mind.
"Grasshopper" does instantly remind me of the Kung Fu series with David Carradine, however.
That says a lot about my age, I suppose
Nope! No blood on the floor here.
I just suggested it here, and various beverages got sprayed on the floor. A few tears of laughter were added shortly afterwards.
If our students want to learn COBOL, we point them to the library where there are a few books on COBOL. When they look blank, we tell them the library is the place with all the books and stuff.
Re: you devil you
Re: Proper programming language
Good points. This is one reason we went back from Java (still used by us for teaching OO) to C for our initial programming course. We find the students learn to understand what is going on better. Having to do your own malloc and free can be a pain, but learning what memory management actually is about is useful.
More importantly, I think it is important to teach the students programming rather than teaching them a programming language. The first is a way to think about solving problems, the second is a tool to achieve a result. You need to learn both of course. In terms of programming languages, the most important skill is to learn how to teach yourself a new one.
Another point is that there are two reasons to learn a new programming language:
1) because you want to work on a project written in that language
2) because you want to learn new ways of thinking about programming
If you have learnt to program in Pascal, learning C does not give you a fundamentally different way of approaching programming problems, but Haskell or Erlang will. A thoughtful discussion on this is found here.
It is also about pattern recognition
Indiscriminate adding of data makes finding any information hard. There is a real risk of drowning interesting patterns in noise. Data != Information
As I like to tell students (over and over again): Adding hay does not make finding needles easier
We do do some work on really big data (vast amount of image data from astronomy and remote sensing), but that data has lots of internal structure which helps finding stuff.
Like the definition of IDEs
I now understand why I avoid them for a lot of tasks
Verity is informative as aver
Re: Emacs: Rejected
Lisp is not a really a problem provided you have sufficient parentheses installed.
Now with that add in W8 might be OK at home
I dread the idea of "upgrading" at home, simply because the missus will freak out with things being in different places (or simply having a different icon/colour/name). You would not believe the level of complaints I got when I installed Office 2010 at her insistence to be compatible with her work environment (Office 2007), and it was not pixel-compatible with her machine at work. Before that I drew flak about having LibreOffice to handle docx files (which always mess files up, according to her). I was somewhat amused that MS-Office 2010 made a similar pig's breakfast out of the same Office 2007 docx files from her work.
Thank God I use LaTeX!!!
Sorry, end of rant, I needed to get that off my chest
With workarounds to make it look like W7 I might be spared quite some pain.
The kids will have no problems with the transition, I would guess.
Nah, ya wee scunner!
It's the Nac Mac Feegle that want those!
They won't buy them of course, not if they can steal them
SEP = Someone Else's Problem
as is SEP-fields to render spacecraft invisible
Venison steak served with a red wine and blackberry sauce is too good to miss. I cooked that while camping in the New Forest.
And I got the venison steak from the local butcher, honest!!
As I stated before
Twinings Prince of Wales tea or the Keemun Congou I can get here in the Netherlands
Recommended infusing time:
3min - ∞
The latter occurs when I am busy coding. This tea does not turn bitter ever (does turn cold however)
Assam is a good alternative, infusing time 3-5 min
Yep, Navaho "wind-talkers"
There was even a movie about that
I wonder if I could confuse would be code breakers by using Welsh (encrypted that is, although places like the above look like crypto to the uninitiated eye).
Re: Fine, but......
Quite a bit of research around here gets funded by Europe.
I will post a link for our students in the history of computing section of our Orientation in Computer Science course.
Re: Ironic? No
Convoluted? Let's compile a ZX-Spectrum emulator using this old C-compiler to use the PDP emulator, running a ZX Spectrum emulator, running a basic interpreter to run a computer game.
Re: "blood flowing through"
If the hand is severed two changes occur either of which might be detected: (i) the blood stops flowing, leading to a change in the Doppler signal (can be integrated into fingerprint scanners as well), and (ii) the blood in the arteries also becomes deoxygenated, leading to those showing up as well. I do not know which is used.
I suddenly have this mental image of the device shouting MURDERER at 100dB when it detects a severed hand of a client. Could be a neat addition.
Sounds like Corsican cheese
It blew up a ship in Asterix on Corsica.
Reported to be rather "pungent" as well
Re: Only windows lets you upgrade...
OpenSUSE upgraded seamlessly from 10.X to 11.X to 12.X for me. It work fine even to the point that between 10.X and 11.X the system partition was upped from ext3 to ext4, but it left the user partition untouched.
I work with a Debian-based distro at work. As long as my compiler/matlab/LaTeX work (oh, and a browser) I am happy with essentially any OS. Multi-media (sound in particular) can be a pain now and then under Linux. On the other hand, I like it when my computer SHUTS UP.
I have used OS-X when visiting other institutes and had no problems with it. The only problem for me is that the current crop of MacBooks in the size I want don't have nVidia graphics (me use CUDA).
I would tax the politicians first, they seem to be producing far more hot air than anybody else, and heating that air must be fuelled by burning carbon-based stuff, so they are producing excess CO2.
As the late sir Patrick said
Whenever there is a comet all the crackpots come out of the woodwork
Re: I am conflicted...
"What sort of IT qualifications can you get at her majestys? ..."
(Master Criminal Solutions Expert)
runs for cover
Re: no touching?
That is a typical MS fanboy dig at linux! Typical Steve Balmer FUD, and totally unfounded too!!!!!!!!!
I, I, I,....
Oh wait, you are talking real penguins. Please excuse me; do carry on.
Sorry, couldn't resist
Mine is the one with the dictionary of bad punnery in the pocket
"Protect your home button"
I read that as "protect your home bottom" in this context
Am I the only one?
Re: It's the Vogons!
Don't forget a packet of peanuts!
It is one thing to take the pictures (essential first step), but it does not end there. What is easily as important is automating the analysis. With the glut of data available, manual analysis is often unacceptably slow. This is one reason we are working together with European partners on massively parallel analysis of huge image data sets. This would allow rapid analysis of damage in the aftermath of disasters, among other applications.
Re: "prehistoric prawn monster"
Given that it was found in China, stir frying with ginger, garlic and a variety of vegetables is more appropriate. Just add a dash of light soy sauce and rice wine vinegar at the end.
Darn, now I am hungry
At least he does not shovel it into his nose or ears.
Re: Machines as dull
Going berserk as a warrior served a similar purpose against human opponents in the past.
Could well work against robots (and perhaps also Vulcans, or anybody else thinking logically)
Nuke from orbit, it's the only way to be sure!
Re: There is a reason for Software Smugness
@ the spectacularly refined chap
My statement is indeed a bit broad (and to generalize is to be an idiot). I was talking about when there is a bottleneck. If there is no bottleneck, there is no need to throw resources at it, hardware or software. The examples I gave are cases with severe bottlenecks.
In your example of the one-off job you are actually also thinking in terms of algorithmics: which one is simpler to implement (and therefore easier to get right). That is why for one-off jobs or experiments I like to use scripting languages (MatLab most of all for my work). Only when heavy lifting is needed (and we have established firmly what we want to compute) do I go for C(++).
You are of course right that there is always a balance to be had between implementation time and total CPU time used. In the very old days CPU time was costly, software development and maintenance time was comparatively low, because code was comparatively compact. Now CPU time is cheap as chips, but code development and maintenance is not, what with the dramatically increased complexity and interconnectedness.
Nowadays, the farmer first glues on some horns and sells it to the abbatoir as a cow.
There is a reason for Software Smugness
You haven't heard of the reverse boast "only by throwing software at it" because of a very simple fact: If I can get more performance out of the same hardware, by designing an O(N) algorithm to replace an O(N^2) I am being smart. Throwing more hardware at a problem when a better algorithmic solution exists is stupid.
I have seen people use weeks of wall-clock time on a 512 core segment of a big machine, simply because their code was bad. My colleague coded the thing properly in C++ and had the code running on his desktop and finishing in a few minutes (O(2^N) vs O(N log N) if I recall correctly). Only throwing hardware at a problem is often wrong. Thinking about better algorithms is never a bad idea.
Once you have really thought about the algorithmics, then you can start throwing more hardware at it (and once you do that, you must rethink the algorithmics again, especially when doing parallel stuff). So in our massive image processing stuff (Gpixel and Tpixel), we first minimize communication and disk-access overhead, and then move to SSD or Fusion-IO stuff.
Ye cannae change the laws of physics Capt'n!!
"The coating is "invisible" and it can be applied to screens and lenses without causing an optical effect."
That is a curious claim (I am being politic about things, just this once), unless the coating has an index of refraction of 1.0 (unlikely) and/or the coating is thinner than a very small fraction of the wavelength of light (some tens of nanometers at most I would guess). I suppose it could be integrated into the design of an anti-reflection coating, but just spraying it on afterwards will change the anti-reflection properties of the coating in general.
When people "explain" finance to me, I always refer to Going Postal. At the end of that book, financiers enter the fray. There is a brilliant passage which reads (approximately):
And they saved the city with gold more easily than any hero could have with steel. .... But it was not so much gold, or even the promise of gold, but more the dream that gold would be there at the end of the rainbow. Provided you did not go and look, of course. And that is called Finance.
You are a wise man, Terry Pratchett.
Has Reg Shoe joined yet?
The one with "Jingo" in the pocket, please
Just goes to show
The old adage:
Nothing is foolproof for a sufficiently talented fool
still holds true
One question I have always asked myself
If the flapping of the proverbial butterfly wing has an impact of the weather, how come scientists could claim with a straight face that extracting several tera-Watts of power from the climate system will have no effect?
This scientist seems to be asking that self-same question.
This does not mean I am against wind power, I just think we should not blithely assume it does not impact climate in some way.
And of course, as Mustrum Ridcully would say, lets find those bloody butterflies that are causing all these storms
I would have voted for names like Arthur Dent or Ford Prefect
but then I never was a Trekkie
All I want
is for the clouds to sod off and let me see the comet C/2011 L4 PanStarrs in March (and comet C/2012 S1 ISON in November and December).
I do not know why I have had such a dismal run of lousy weather preventing me from spending more than a single night per month watching the stars (or indeed whether this is exceptional), I just want some clear skies!!
- NASA boffin: RIDDLE of odd BULGE FOUND on MOON is SOLVED
- BuzzGasm! Thirteen Astonishing True Facts You Never Knew About SCREWS
- Microsoft's Euro cloud darkens: US FEDS can dig into foreign servers
- Worstall on Wednesday YES, iPhones ARE getting slower with each new release of iOS
- Plug and PREY: Hackers reprogram USB drives to silently infect PCs