"As Children most cops and most judges were the bullies"..That's a pretty broad sweeping statement that may or may not be true that I've heard anecdotally all my life . I would love to see references to back this up. It's believable, but I have a hard time with such statements.. Perhaps a larger fraction of bullies, but it's hard to believe that most of them are this way. You could equally argue that cops spend most of their day helping people, and are mostly decent folks. The highway patrol spends most of their time helping stranded motorists, etc..
I met a guy that used to work at NIST that mentioned that their clocks are so sensitive, they can tell what floor the atomic clocks are on because of of the slightly different gravitational potential each clock experiences. I wonder what kind of resolution the can resolve. Can a very massive bolder throw off the clock a little?..perhaps one day we will have to keep better track of the local gravitational potential well. It's possible to measure the gravitational constant with simple apparatus at home. Using two massive bodies in a torsion pendulum arrangement, you can estimate "big G" --
http://www.owlnet.rice.edu/~do...
I understand that the Russians are the only ones that can put people in the space station, and that the US serves as the ground control. If Russia refuses to let Americans on to the space station, what are the chances that the US would not coordinate ground control for an exclusively Russian or non-American crew? I've read from a number of sources speculating on this probability. What kind of ground support and communications structure are needed to keep the station operational? With the addition of the alpha magnetic spectrometer, the ISS has become a lot more interesting. : http://ams.nasa.gov/
Perhaps this is one thing that both countries really care about, it's one thing that could serve as leverage between then; a negotiation point.
It's a shame that the cooperation deminishing. The Russians are doing some really fantastic work. They've put a radio telescope in orbit: They launched a radio telescope (Spektr-R) into space. By synchronizing this telescope with earth based telescopes, it can resolve features that are 1250x times smaller than what Hubble can see (40u-arc-seconds vs 0.05 arc-seconds).. Did you know that by pointing all of the radio dishes on one side of the earth, and that knowing the exact time radio waves hit each receiver with atomic clocks, you can out resolve any optical telescope on earth? We can literally see finer details with a radio telescope than we can with our best optical ones (using "VLBI " interferometry). The more separation between radio dishes, the better the angular resolution; and now we have one in orbit that will give us much much better resolving power. We may be able to "see" planets with radio waves. (I'd love to hear from radio astronomers about the practical limitations of this -- real world vs back-of-the envelope)
They only started recently announcing their achievements on their website. Several of my friends joked that the reason we heard nothing for so long was that it was an expensive and embarrassing dud. It works, but they don't market or advertise themselves well.
http://www.asc.rssi.ru/radioas...
..It's possible to teach your kids how to check your answers once they're made, like plugging the answers back into the equations, graphing results, etc. You can minimize errors this way and teach intuition.. You can teach a rigorous methodology that may otherwise not be stressed in school for checking your results, significant figures, etc. There is also always more than one way to solve a math or physics problem..
It's also highly useful to reach context, and relevance. Concrete real-world examples make the subject come alive.. Involving them in experiments at home is also a fun way to teach kids. What kids often need is an emotional connection to the material to motivate them to learn subjects they may be otherwise uninterested.
I hated math until I found out that you could measure the heights of mountains, and how important it was to understand electronics. A demonstration involving modulating a lectures voice over a laser beam, and seeing the resulting waveforms on an oscilloscope got me hooked.
Most of my teachers seemed to have a deep suspicion of science, and did a very poor and uninspiring job to trying to teach it. I'm glad there were a few people around out of school that got me excited about it. I got my first cheap/old/used oscilloscope in the 6th grade. It was a trans formative moment about gaining insight about how the world works..
I have relatives in Ukraine living in Odessa oblast, Novoukrainka, Kiev and in Lviv, and friends in Crimea. Those listening to Russian news, are saying that ultra-nationalists are shooting Russians in the street in Lviv. Panicked, we called our relatives, and found they are absolutely fine, and the streets are quiet. A percentage of the population believes whatever the Russian media tells them; a form of information bias. Unfortunately, Russian media has past Ukraine in a pretty negative light, and have now resorted to telling outright lies, in what looks like an attempt to soften up Russian sympathetic Ukrainians to invasion; dividing and conquering within with an information war..
Hitler once said -- if you're going to tell a lie, don't tell a little one, tell a big one. Ukraine is a poor country. They just had to deal with the most corrupt leader they had ever experienced. Russia has somehow convinced it's citizens that ultra-nationalists have taken over the country. In reality closer ties with the EU require tolerance for minorities.
The elections are due at the end of May. All Russia would have to do to insure that a Russian sympathetic government is elected is to continue with an information war. It was/is unnecessary to send in the army, other than to carve out pieces of Ukraine.
There are billions of embedded systems out there, and most of them are not connected to the internet. I've designed embedded control systems for most of my career, and can attest to the many advantages a digital control system has over an analog one. Analog still has it's place (op-amps are pretty fast & cheap), but it's often quite useful to have a computer do it. Most capacitors have a 20% tolerance or so, have a temperature tolerance, and have values that drift. Your control system can drift over time, and may even become unstable due to the aging of the components in the compensator (e.g. PI, PID,lead/lag).. Also a microcontroller wins hands down when it comes to long time constants with any kind of precision (millihertz). It's harder to make very long RC time constants, and trust those times. Microcontrollers/FPGA's are good for a wide control loops including those that are very fast or very very slow. Microcontrollers allow you to do things like adaptive control when you plant can vary over time like maintaining a precision temperature and ramp time of a blast-furnace when the volume inside can change wildly.. They also allow you to easily handle things like transport/phase lags, and a lot of corner conditions, system changes -- all without changing any hardware..
I am happy to see the same trend with software-defined radio, where we try to digitize as much of the radio as possible, as close to the antenna as possible.. Analog parts add noise, offsets, drift, cross-talk exhibit leakag,etc.. Microcontrollers allow us to minimize as much of the analog portion as possible.
Is it possible to run windows 7 apps on windows 8 ?..Is there an easy means to click on a file and tell it to install it as if it was running on windows 7?
I have been a long-time windows user, and like the overall user experience and graphics, but it does give me pause about much easier it is to run old programs in Linux. It's been my experience that you can get programs going from 10+ years ago because you have the source you can build from.. I maintain many old boxes for software/hardware compatibility reasons (95,98,2000,XP,Win7). I installed a virtual machine in windows 7, only to find that my video card didn't have an XP driver other than the default windows one.. How do people handle unsupported hardware in their virtual machines in Windows? Are there ways around them so you can get you "old games" running on a new machine?..I really like the people at Good Old Games that figured out a way to make a large selection games run on a modern.. I only wish they had more titles....We can run old Cobol and Fortran programs from 55+ years ago.. It would be nice to see the same for our modern programs..This is one thing I hope for as computers mature.
If you look on the top of this vehicle, you will find a velodyne lidar, that sweeps the field of view at 15Hz with 64 beams. Here is there website:
http://velodynelidar.com/lidar..... From my understanding, there are 64 laser diodes mounted as a stripe, and 64 corresponding avalanche photodiodes , each group of 8 detectors is being fed to an 8-bit 3 gigasample per second ADC.
These units sell for $80K, and is one of the factors effecting wider adoption. I understand that there is a lot of demand among the auto and trucking industries if these can be made cheaper. This technology will become much cheaper as the cost of the ADC's drop. Right now, a 3GSPS adc costs about $600. A few years ago, this is what a 1GSPS part cost... process node shrinkage will make this kind of technology affordable, and open up a lot of other interesting ideas.
Please check that your memory is not corrupt. You might have a real hardware problem. I've had a number of cases where I had bad ram, e.g. doing a memcheck at boot failed. It's amazing that the OS could run at all in these cases, but it did. Installing new applications and moving big files were problematic, but everything else worked .
-Joe
I bought a laptop, only to find that my development tools (FPGA's) were stable under windows 7, but were buggy under windows 8. I went through all the hassle or removing windows 8 to install windows 7 (you have to dig somewhere in windows 8 to "unlock the bios", reformat the drive for a different file type, etc) , only to find out that I couldn't get all the windows 7 drivers. Even basic stuff like the ethernet did not work. I had not experienced to what extent a new PC was non functional after installing the OS. I had to restore it back to windows 8, and buy a different laptop with windows 7 installed.
As a long term windows user, I've needed to dual boot Linux for my recent development work (running linux on an embedded target), and have been impressed by the experience. You get a working word-processor, a spreadsheet, and power-point that can open up microsoft stuff...One of my biggest hassles developing on windows is dealing with USB drivers and JTAG tools..The experience is much easier in linux, where it's easier to undo if you get yourself into trouble with the wrong driver.
It's one thing to scan something that stationary, it's quite another thing to continuously keep track of a 360 degree field of view around the scanner.
The self driving car from Google, I think, uses a custom detector from Velodyne that spins at 5-15Hz:
http://velodynelidar.com/lidar/lidar.aspx
I know of at least one start-up company called Quanergy that plans on competing in this space to give cars/drivers better real-time situational awareness. Hopefully they'll be able to develop something that is cheap / good enough to be part of a futuristic car. Perhaps this will help in car accident reduction, and a saving of lives:
http://www.youtube.com/watch?v=qwcSmo3dzVM
Your question was fair, all jokes aside -- It would be interesting to hear the perspective of a real CE on the matter, and going into things like the soil composition, etc.. This is one thing I love about SD. It's not all that unusual to hear from experts in a particular field.
One thing that I lament about scientific publications, is that the results are boiled down to a few pages. You rarely see raw data , an generally only the statistical analysis. I would like to see web links in journals that include more of the raw data, the programs that generated that data, etc. We live in a day in age when gigabytes are cheap. It would be a lot easier to duplicate someone's work for peer review if the inherent data & analysis programs were more accessible. Although, there are a fair number of organizations that have no interest in making their data easier to understand because of commercialization and patent issues..
I for one see a lot of EE/CS papers that are devoid of source code. Source code is cumbersome to print, which is why I think it's rarely included as it would take up too much paper. I do think the inclusion of source code facilitates a better understanding of the authors intent. I would love to see CS papers links hyperlinks to a database of the journal publisher as a new standard in the "information age".
To what extent can meteorology techniques, esp. non-destructive, be used ? E.g. x-ray crystallography,microscopy to study crystal grains, electron-microscopy, spectroscopy, etc?
If you dig through the links, you'll find that they're developing a free-electron laser: http://www.boeing.com/assets/pdf/defense-space/ic/des/files/DES_overview.pdf
I'm pretty amazed that they can get something like that working in a truck. SLAC was converted into a free-electron laser. http://en.wikipedia.org/wiki/Free-electron_laser. A free electron laser starts as an accelerator and ends up turning into a beam of light; I thought these things had to be huge in order to work.. They were not clear about what they were currently using.. A compact high energy free electron laser opens up a lot of possibilities.
I too have one of those SoC Boards. I would love to see your compiled errata & additional notes about how you were able to get it running. Is there / will there be a link somewhere we might have access to ?
-Joe
Dave Barry on College -
"After you've been in college for a year or so, you're supposed to choose a major, which is the subject you intend to memorize and forget the most things about. Here is a very important piece of advice: be sure to choose a major that does not involve Known Facts and Right Answers. This means you must not major in mathematics, physics, biology, or chemistry, because these subjects involve actual facts.."
"So you should major in subjects like English, philosophy, psychology, and sociology -- subjects in which nobody really understands what anybody else is talking about, and which involve virtually no actual facts. I attended classes in all these subjects, so I'll give you a quick overview of each:"
...
"PHILOSOPHY: Basically, this involves sitting in a room and deciding there is no such thing as reality and then going to lunch. You should major in philosophy if you plan to take a lot of drugs...."
I am mainly a firmware engineer, but I do have respect for software engineering. It's all about productivity. Modern programming languages and methods allow you to accomplish a lot.e.g multi-threaded, multi-processor applications with languages like C#. . There has been a continuous evolution of programming methods, and some applications have taken advantage of it. I worked at a company that made DNA sequencers, and could see how quickly the language allowed them to tackle complex tasks like image processing, base-calling, base-alignment, etc,. A good software engineer will tell you that it will always take more time, more error prone, etc, to do complicated tasks in a "more primitive language".
What will always be key is a fundamental understanding of algorithms. You can easily get orders of magnitude improvement.. Too many programmers use bruit force methods, regardless of language..
Slashdot Mirror
..I think if you videotape your car getting stolen without the sound, it's completely admissible..
"As Children most cops and most judges were the bullies"..That's a pretty broad sweeping statement that may or may not be true that I've heard anecdotally all my life . I would love to see references to back this up. It's believable, but I have a hard time with such statements.. Perhaps a larger fraction of bullies, but it's hard to believe that most of them are this way. You could equally argue that cops spend most of their day helping people, and are mostly decent folks. The highway patrol spends most of their time helping stranded motorists, etc..
I met a guy that used to work at NIST that mentioned that their clocks are so sensitive, they can tell what floor the atomic clocks are on because of of the slightly different gravitational potential each clock experiences. I wonder what kind of resolution the can resolve. Can a very massive bolder throw off the clock a little? ..perhaps one day we will have to keep better track of the local gravitational potential well. It's possible to measure the gravitational constant with simple apparatus at home. Using two massive bodies in a torsion pendulum arrangement, you can estimate "big G" --
http://www.owlnet.rice.edu/~do...
Here is an wikipedia article that mentions the phenomena with atomic clocks: http://en.wikipedia.org/wiki/G...
I understand that the Russians are the only ones that can put people in the space station, and that the US serves as the ground control. If Russia refuses to let Americans on to the space station, what are the chances that the US would not coordinate ground control for an exclusively Russian or non-American crew? I've read from a number of sources speculating on this probability. What kind of ground support and communications structure are needed to keep the station operational? With the addition of the alpha magnetic spectrometer, the ISS has become a lot more interesting. : http://ams.nasa.gov/
Perhaps this is one thing that both countries really care about, it's one thing that could serve as leverage between then; a negotiation point.
It's a shame that the cooperation deminishing. The Russians are doing some really fantastic work. They've put a radio telescope in orbit: They launched a radio telescope (Spektr-R) into space. By synchronizing this telescope with earth based telescopes, it can resolve features that are 1250x times smaller than what Hubble can see (40u-arc-seconds vs 0.05 arc-seconds).. Did you know that by pointing all of the radio dishes on one side of the earth, and that knowing the exact time radio waves hit each receiver with atomic clocks, you can out resolve any optical telescope on earth? We can literally see finer details with a radio telescope than we can with our best optical ones (using "VLBI " interferometry). The more separation between radio dishes, the better the angular resolution; and now we have one in orbit that will give us much much better resolving power. We may be able to "see" planets with radio waves. (I'd love to hear from radio astronomers about the practical limitations of this -- real world vs back-of-the envelope)
They only started recently announcing their achievements on their website. Several of my friends joked that the reason we heard nothing for so long was that it was an expensive and embarrassing dud. It works, but they don't market or advertise themselves well. http://www.asc.rssi.ru/radioas...
..It's also highly useful to [teach] context, and relevance...
It's also highly useful to reach context, and relevance. Concrete real-world examples make the subject come alive.. Involving them in experiments at home is also a fun way to teach kids. What kids often need is an emotional connection to the material to motivate them to learn subjects they may be otherwise uninterested. I hated math until I found out that you could measure the heights of mountains, and how important it was to understand electronics. A demonstration involving modulating a lectures voice over a laser beam, and seeing the resulting waveforms on an oscilloscope got me hooked.
Most of my teachers seemed to have a deep suspicion of science, and did a very poor and uninspiring job to trying to teach it. I'm glad there were a few people around out of school that got me excited about it. I got my first cheap/old/used oscilloscope in the 6th grade. It was a trans formative moment about gaining insight about how the world works..
I have relatives in Ukraine living in Odessa oblast, Novoukrainka, Kiev and in Lviv, and friends in Crimea. Those listening to Russian news, are saying that ultra-nationalists are shooting Russians in the street in Lviv. Panicked, we called our relatives, and found they are absolutely fine, and the streets are quiet. A percentage of the population believes whatever the Russian media tells them; a form of information bias. Unfortunately, Russian media has past Ukraine in a pretty negative light, and have now resorted to telling outright lies, in what looks like an attempt to soften up Russian sympathetic Ukrainians to invasion; dividing and conquering within with an information war..
Hitler once said -- if you're going to tell a lie, don't tell a little one, tell a big one. Ukraine is a poor country. They just had to deal with the most corrupt leader they had ever experienced. Russia has somehow convinced it's citizens that ultra-nationalists have taken over the country. In reality closer ties with the EU require tolerance for minorities.
The elections are due at the end of May. All Russia would have to do to insure that a Russian sympathetic government is elected is to continue with an information war. It was/is unnecessary to send in the army, other than to carve out pieces of Ukraine.
There are billions of embedded systems out there, and most of them are not connected to the internet. I've designed embedded control systems for most of my career, and can attest to the many advantages a digital control system has over an analog one. Analog still has it's place (op-amps are pretty fast & cheap), but it's often quite useful to have a computer do it. Most capacitors have a 20% tolerance or so, have a temperature tolerance, and have values that drift. Your control system can drift over time, and may even become unstable due to the aging of the components in the compensator (e.g. PI, PID,lead/lag) .. Also a microcontroller wins hands down when it comes to long time constants with any kind of precision (millihertz). It's harder to make very long RC time constants, and trust those times. Microcontrollers/FPGA's are good for a wide control loops including those that are very fast or very very slow. Microcontrollers allow you to do things like adaptive control when you plant can vary over time like maintaining a precision temperature and ramp time of a blast-furnace when the volume inside can change wildly.. They also allow you to easily handle things like transport/phase lags, and a lot of corner conditions, system changes -- all without changing any hardware..
I am happy to see the same trend with software-defined radio, where we try to digitize as much of the radio as possible, as close to the antenna as possible.. Analog parts add noise, offsets, drift, cross-talk exhibit leakag,etc.. Microcontrollers allow us to minimize as much of the analog portion as possible.
Is it possible to run windows 7 apps on windows 8 ? ..Is there an easy means to click on a file and tell it to install it as if it was running on windows 7?
I have been a long-time windows user, and like the overall user experience and graphics, but it does give me pause about much easier it is to run old programs in Linux. It's been my experience that you can get programs going from 10+ years ago because you have the source you can build from.. I maintain many old boxes for software/hardware compatibility reasons (95,98,2000,XP,Win7). I installed a virtual machine in windows 7, only to find that my video card didn't have an XP driver other than the default windows one.. How do people handle unsupported hardware in their virtual machines in Windows? Are there ways around them so you can get you "old games" running on a new machine? ..I really like the people at Good Old Games that figured out a way to make a large selection games run on a modern.. I only wish they had more titles. ...We can run old Cobol and Fortran programs from 55+ years ago.. It would be nice to see the same for our modern programs..This is one thing I hope for as computers mature.
If you look on the top of this vehicle, you will find a velodyne lidar, that sweeps the field of view at 15Hz with 64 beams. Here is there website: http://velodynelidar.com/lidar... .. From my understanding, there are 64 laser diodes mounted as a stripe, and 64 corresponding avalanche photodiodes , each group of 8 detectors is being fed to an 8-bit 3 gigasample per second ADC.
These units sell for $80K, and is one of the factors effecting wider adoption. I understand that there is a lot of demand among the auto and trucking industries if these can be made cheaper. This technology will become much cheaper as the cost of the ADC's drop. Right now, a 3GSPS adc costs about $600. A few years ago, this is what a 1GSPS part cost... process node shrinkage will make this kind of technology affordable, and open up a lot of other interesting ideas.
Please check that your memory is not corrupt. You might have a real hardware problem. I've had a number of cases where I had bad ram, e.g. doing a memcheck at boot failed. It's amazing that the OS could run at all in these cases, but it did. Installing new applications and moving big files were problematic, but everything else worked . -Joe
I bought a laptop, only to find that my development tools (FPGA's) were stable under windows 7, but were buggy under windows 8. I went through all the hassle or removing windows 8 to install windows 7 (you have to dig somewhere in windows 8 to "unlock the bios", reformat the drive for a different file type, etc) , only to find out that I couldn't get all the windows 7 drivers. Even basic stuff like the ethernet did not work. I had not experienced to what extent a new PC was non functional after installing the OS. I had to restore it back to windows 8, and buy a different laptop with windows 7 installed.
As a long term windows user, I've needed to dual boot Linux for my recent development work (running linux on an embedded target), and have been impressed by the experience. You get a working word-processor, a spreadsheet, and power-point that can open up microsoft stuff...One of my biggest hassles developing on windows is dealing with USB drivers and JTAG tools..The experience is much easier in linux, where it's easier to undo if you get yourself into trouble with the wrong driver.
It's one thing to scan something that stationary, it's quite another thing to continuously keep track of a 360 degree field of view around the scanner. The self driving car from Google, I think, uses a custom detector from Velodyne that spins at 5-15Hz: http://velodynelidar.com/lidar/lidar.aspx
I know of at least one start-up company called Quanergy that plans on competing in this space to give cars/drivers better real-time situational awareness. Hopefully they'll be able to develop something that is cheap / good enough to be part of a futuristic car. Perhaps this will help in car accident reduction, and a saving of lives: http://www.youtube.com/watch?v=qwcSmo3dzVM
Your question was fair, all jokes aside -- It would be interesting to hear the perspective of a real CE on the matter, and going into things like the soil composition, etc.. This is one thing I love about SD. It's not all that unusual to hear from experts in a particular field.
One thing that I lament about scientific publications, is that the results are boiled down to a few pages. You rarely see raw data , an generally only the statistical analysis. I would like to see web links in journals that include more of the raw data, the programs that generated that data, etc. We live in a day in age when gigabytes are cheap. It would be a lot easier to duplicate someone's work for peer review if the inherent data & analysis programs were more accessible. Although, there are a fair number of organizations that have no interest in making their data easier to understand because of commercialization and patent issues..
I for one see a lot of EE/CS papers that are devoid of source code. Source code is cumbersome to print, which is why I think it's rarely included as it would take up too much paper. I do think the inclusion of source code facilitates a better understanding of the authors intent. I would love to see CS papers links hyperlinks to a database of the journal publisher as a new standard in the "information age".
To what extent can meteorology techniques, esp. non-destructive, be used ? E.g. x-ray crystallography ,microscopy to study crystal grains, electron-microscopy, spectroscopy, etc?
If you dig through the links, you'll find that they're developing a free-electron laser: http://www.boeing.com/assets/pdf/defense-space/ic/des/files/DES_overview.pdf I'm pretty amazed that they can get something like that working in a truck. SLAC was converted into a free-electron laser. http://en.wikipedia.org/wiki/Free-electron_laser. A free electron laser starts as an accelerator and ends up turning into a beam of light; I thought these things had to be huge in order to work.. They were not clear about what they were currently using.. A compact high energy free electron laser opens up a lot of possibilities.
Great. Thank you for taking the time to write all this for us. -Joe
There is more than one SoC board. You can get one for $300 at Terasic, that designs many of the low-cost demoboards for Altera. http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=165&No=816
I too have one of those SoC Boards. I would love to see your compiled errata & additional notes about how you were able to get it running. Is there / will there be a link somewhere we might have access to ? -Joe
I am not an idiot, at least most of the time, but we all have our little intransigent moments..
Etymology of "Idiot" --a word derived from the Greek "..." ("person lacking professional skill")
http://en.wikipedia.org/wiki/Idiot
"So you should major in subjects like English, philosophy, psychology, and sociology -- subjects in which nobody really understands what anybody else is talking about, and which involve virtually no actual facts. I attended classes in all these subjects, so I'll give you a quick overview of each:"
"PHILOSOPHY: Basically, this involves sitting in a room and deciding there is no such thing as reality and then going to lunch. You should major in philosophy if you plan to take a lot of drugs...."
http://users.soe.ucsc.edu/~martine/light/barrycollege.html
Unfortunately, some aspects of physics are starting to sound like Dave Barry's take on Philosophy..
I am mainly a firmware engineer, but I do have respect for software engineering. It's all about productivity. Modern programming languages and methods allow you to accomplish a lot.e.g multi-threaded, multi-processor applications with languages like C#. . There has been a continuous evolution of programming methods, and some applications have taken advantage of it. I worked at a company that made DNA sequencers, and could see how quickly the language allowed them to tackle complex tasks like image processing, base-calling, base-alignment, etc,. A good software engineer will tell you that it will always take more time, more error prone, etc, to do complicated tasks in a "more primitive language".
What will always be key is a fundamental understanding of algorithms. You can easily get orders of magnitude improvement.. Too many programmers use bruit force methods, regardless of language..
Focal size (in), Expected activity (Ci)
0.120, 30 to 33
0.150, 50 to 55
0.172, 75 to 80
0.187, 100 to 110
0.217, 150 to 155
0.236, 200 to 210
0.268, 290 to 300
oops -- please disregard, I meant to post in another thread. I'm trying to find a way to remove a post once made, but I can't seem to find it.